56,642 research outputs found
Comment on: "Estimating the Hartree-Fock limit from finite basis set calculations" [Jensen F (2005) Theor Chem Acc 113:267]
We demonstrate that a minor modification of the extrapolation proposed by
Jensen [(2005): Theor Chem Acc 113:267] yields very reliable estimates of the
Hartree-Fock limit in conjunction with correlation consistent basis sets.
Specifically, a two-point extrapolation of the form
yields HF limits
with an RMS error of 0.1 millihartree using aug-cc-pVQZ and
aug-cc-pV5Z basis sets, and of 0.01 millihartree using aug-cc-pV5Z and
aug-cc-pV6Z basis sets.Comment: Theoretical Chemistry Accounts, in pres
Inverse Statistics in the Foreign Exchange Market
We investigate intra-day foreign exchange (FX) time series using the inverse
statistic analysis developed in [1,2]. Specifically, we study the time-averaged
distributions of waiting times needed to obtain a certain increase (decrease)
in the price of an investment. The analysis is performed for the Deutsch
mark (DM) against the US. With high statistical
significance, the presence of "resonance peaks" in the waiting time
distributions is established. Such peaks are a consequence of the trading
habits of the markets participants as they are not present in the corresponding
tick (business) waiting time distributions. Furthermore, a new {\em stylized
fact}, is observed for the waiting time distribution in the form of a power law
Pdf. This result is achieved by rescaling of the physical waiting time by the
corresponding tick time thereby partially removing scale dependent features of
the market activity.Comment: 8 pages. Accepted Physica
Technology advancement of the static feed water electrolysis process
Some results are presented of a research and development program to continue the development of a method to generate oxygen for crew metabolic consumption during extended manned space flights. The concept being pursued is that of static feed water electrolysis. Specific major results of the work included: (1) completion of a 30-day electrode test using a Life Systems, Inc.-developed high performance catalyst. During startup the cell voltages were as low as 1.38 V at current densities of 108 mA/sq cm (100 ASF) and temperatures of 355 K (180 F). At the end of 30 days of testing the cell voltages were still only 1.42 V at 108 mA/sq cm, (2) determination that the Static Feed Water Electrolysis Module does not release an aerosol of the cell electrolyte into the product gas streams after a break-in period of 24 hours following a new electrolyte charge, and (3) completion of a detailed design analysis of an electrochemical Oxygen Generation Subsystem at a three-man level (4.19 kg/day (9.24 lb/day) of oxygen)
Dynamic models of residential segregation: brief review, analytical resolution and study of the introduction of coordination
In his 1971's Dynamic Models of Segregation paper, the economist Thomas C.
Schelling showed that a small preference for one's neighbors to be of the same
color could lead to total segregation, even if total segregation does not
correspond to individual preferences and to a residential configuration
maximizing the collective utility.
The present work is aimed at deepening the understanding of the properties of
dynamic models of segregation based on Schelling's hypotheses. Its main
contributions are (i) to offer a comprehensive and up-to-date review of this
family of models; (ii) to provide an analytical solution to the most general
form of this model under rather general assumptions; to the best of our
knowledge, such a solution did not exist so far; (iii) to analyse the effect of
two devices aimed at decreasing segregation in such a model.Comment: 52 pages, 21 figures, working pape
Compressive Parameter Estimation for Sparse Translation-Invariant Signals Using Polar Interpolation
We propose new compressive parameter estimation algorithms that make use of
polar interpolation to improve the estimator precision. Our work extends
previous approaches involving polar interpolation for compressive parameter
estimation in two aspects: (i) we extend the formulation from real non-negative
amplitude parameters to arbitrary complex ones, and (ii) we allow for mismatch
between the manifold described by the parameters and its polar approximation.
To quantify the improvements afforded by the proposed extensions, we evaluate
six algorithms for estimation of parameters in sparse translation-invariant
signals, exemplified with the time delay estimation problem. The evaluation is
based on three performance metrics: estimator precision, sampling rate and
computational complexity. We use compressive sensing with all the algorithms to
lower the necessary sampling rate and show that it is still possible to attain
good estimation precision and keep the computational complexity low. Our
numerical experiments show that the proposed algorithms outperform existing
approaches that either leverage polynomial interpolation or are based on a
conversion to a frequency-estimation problem followed by a super-resolution
algorithm. The algorithms studied here provide various tradeoffs between
computational complexity, estimation precision, and necessary sampling rate.
The work shows that compressive sensing for the class of sparse
translation-invariant signals allows for a decrease in sampling rate and that
the use of polar interpolation increases the estimation precision.Comment: 13 pages, 5 figures, to appear in IEEE Transactions on Signal
Processing; minor edits and correction
Compressive Time Delay Estimation Using Interpolation
Time delay estimation has long been an active area of research. In this work,
we show that compressive sensing with interpolation may be used to achieve good
estimation precision while lowering the sampling frequency. We propose an
Interpolating Band-Excluded Orthogonal Matching Pursuit algorithm that uses one
of two interpolation functions to estimate the time delay parameter. The
numerical results show that interpolation improves estimation precision and
that compressive sensing provides an elegant tradeoff that may lower the
required sampling frequency while still attaining a desired estimation
performance.Comment: 5 pages, 2 figures, technical report supporting 1 page submission for
GlobalSIP 201
EVALUATING NEW FOOD TECHNOLOGIES IN PORK PRODUCTION
Pork products, fat modification, feeding experiment, profitability, Livestock Production/Industries,
Global minimum determination of the Born-Oppenheimer surface within density functional theory
We present a novel method, which we call dual minima hopping method (DMHM),
that allows us to find the global minimum of the potential energy surface (PES)
within density functional theory for systems where a fast but less accurate
calculation of the PES is possible. This method can rapidly find the ground
state configuration of clusters and other complex systems with present day
computer power by performing a systematic search. We apply the new method to
silicon clusters. Even though these systems have already been extensively
studied by other methods, we find new configurations that are lower in energy
than the previously found.Comment: 4 pages, 3 figures, minor changes, more structures are presented no
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