12,657 research outputs found
Superfluid vs Ferromagnetic Behaviour in a Bose Gas of Spin-1/2 Atoms
We study the thermodynamic phases of a gas of spin-1/2 atoms in the
Hartree-Fock approximation. Our main result is that, for repulsive or
weakly-attractive inter-component interaction strength, the superfluid and
ferromagnetic phase transitions occur at the same temperature. For
strongly-attractive inter-component interaction strength, however, the
ferromagnetic phase transition occurs at a higher temperature than the
superfluid phase transition. We also find that the presence of a condensate
acts as an effective magnetic field that polarizes the normal cloud. We finally
comment on the validity of the Hartree-Fock approximation in describing
different phenomena in this system.Comment: 10 pages, 2 figure
Application of a meshless method in electromagnetics
Author name used in this publication: S. L. HoAuthor name used in this publication: J. M. MachadoAuthor name used in this publication: H. C. Wong2001-2002 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
A modified ant colony optimization algorithm modeled on tabu-search methods
Author name used in this publication: S. L. Ho2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
A self-learning simulated annealing algorithm for global optimizations of electromagnetic devices
Author name used in this publication: S. L. Ho2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
A combined wavelet-element free Galerkin method for numerical calculations of electromagnetic fields
Author name used in this publication: S. L. HoAuthor name used in this publication: J. M. Machado2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
A new implementation of population based incremental learning method for optimizations in electromagnetics
Author name used in this publication: S. L. Ho2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
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Covariance Analysis of LAV Robust Dynamic State Estimation in Power Systems
In power system state estimation, the robust
Least Absolute Value robust dynamic estimator is well-known.
However, the covariance of the state estimation error cannot
be obtained easily. In this paper, an analytical equation is
derived using Influence Function approximation to analyze the
covariance of the robust Least Absolute Value dynamic state
estimator. The equation gives insights into the precision of the
estimation and can be used to express the variances of the
state estimates as functions of measurement noise variances,
enabling the selection of sensors for specified estimator precision.
Simulations on the IEEE 14-bus, 30-bus and 118-bus
systems are given to illustrate the usefulness of the equation.
Monte-Carlo experiments can also be used to determine the
covariance, but many data points are needed and hence many
runs are required to achieve convergence. Our result shows
that to obtain the covariance of the state estimation error, the
analytical equation proposed in this paper is four orders of
magnitude faster than a 10,000-run Monte-Carlo experiment
on both the IEEE 14-bus and 30-bus systems.National Research Foundation Singapor
Effects of built environment on walking among Hong Kong older adults
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Wavelet-Galerkin method for computations of electromagnetic fields-computation of connection coefficients
Author name used in this publication: S. L. HoAuthor name used in this publication: H. C. Wong2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
An improved tabu-based vector optimal algorithm for design optimizations of electromagnetic devices
Author name used in this publication: S. Y. YangAuthor name used in this publication: S. L. HoAuthor name used in this publication: J. M. MachadoAuthor name used in this publication: Edward W. C. Lo2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
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