5,084 research outputs found
Genetic algorithms with elitism-based immigrants for changing optimization problems
Copyright @ Springer-Verlag Berlin Heidelberg 2007.Addressing dynamic optimization problems has been a challenging task for the genetic algorithm community. Over the years, several approaches have been developed into genetic algorithms to enhance their performance in dynamic environments. One major approach is to maintain the diversity of the population, e.g., via random immigrants. This paper proposes an elitism-based immigrants scheme for genetic algorithms in dynamic environments. In the scheme, the elite from previous generation is used as the base to create immigrants via mutation to replace the worst individuals in the current population. This way, the introduced immigrants are more adapted to the changing environment. This paper also proposes a hybrid scheme that combines the elitism-based immigrants scheme with traditional random immigrants scheme to deal with significant changes. The experimental results show that the proposed elitism-based and hybrid immigrants schemes efficiently improve the performance of genetic algorithms in dynamic environments
Molecular dynamics simulations of oxide memristors: thermal effects
We have extended our recent molecular-dynamic simulations of memristors to
include the effect of thermal inhomogeneities on mobile ionic species appearing
during operation of the device. Simulations show a competition between an
attractive short-ranged interaction between oxygen vacancies and an enhanced
local temperature in creating/destroying the conducting oxygen channels. Such a
competition would strongly affect the performance of the memristive devices.Comment: submit/0169777; 6 pages, 4 figure
From âCinderellaâ to âBeloved Princessâ: The Evolution of Early Childhood Education Policy in China
published_or_final_versio
Functional Diversity of Microbial Communities in Sludge-Amended Soils
AbstractThe BIOLOG method was applied to exploration of functional diversity of soil microbial communities in sludge-amended soils sampled from the Yangtze River Delta. Results indicated that metabolic profile, functional diversity indexes and Kinetic parameters of the soil microbial communities changed following soil amendment with sewage sludge, suggesting that the changes occurred in population of the microbes capable of exploiting carbon substrates and in this capability as well. The kinetic study of the functional diversity revealed that the metabolic profile of the soil microbial communities exhibited non-linear correlation with the incubation time, showing a curse of sigmoid that fits the dynamic model of growth of the soil microbial communities. In all the treatments, except for treatments of coastal fluvo-aquic soil amended with fresh sludge and dried sludge from Hangzhou, kinetic parameters K and r of the functional diversity of the soil microbial communities decreased significantly and parameter S increased. Changes in characteristics of the functional diversity well reflected differences in C utilizing capacity and model of the soil microbial communities in the sludge-amended soils, and changes in functional diversity of the soil microbial communities in a particular eco-environment, like soil amended with sewage sludge
Understanding Intention to Explore Business Intelligence Systems: The Role of Fit and Engagement
This paper explores how user engagement affects usersâ intention to explore business intelligence system (BIS) and how user engagement is promoted by the cognitive fit between BIS interface and tasks and the regulatory compatibility between BIS interface and personal characteristics, such as style of information processing. Results from the lab experiment suggest that the cognitive fit and the regulatory compatibility could both influence usersâ engagement experience, which in turn affected usersâ intention to explore BIS. This study may contribute to the extant information systems (IS) literature by uncovering the impacts of engagement experience on intention to explore and responding to the call for investigation of the BIS context where rich visualizations of the systems influence usersâ engagement experience
Binding energies and electronic structures of adsorbed titanium chains on carbon nanotubes
We have studied the binding energies and electronic structures of metal (Ti,
Al, Au) chains adsorbed on single-wall carbon nanotubes (SWNT) using first
principles methods. Our calculations have shown that titanium is much more
favored energetically over gold and aluminum to form a continuous chain on a
variety of SWNTs. The interaction between titanium and carbon nanotube
significantly modifies the electronic structures around Fermi energy for both
zigzag and armchair tubes. The delocalized 3d electrons from the titanium chain
generate additional states in the band gap regions of the semiconducting tubes,
transforming them into metals.Comment: 4 pages, 3 figure
Mass Suppression in Octet Baryon Production
There is a striking suppression of the cross section for production of octet
baryons in annihilation, as the mass of the produced hadron
increases. We present a simple parametrization for the fragmentation functions
into octet baryons guided by two input models: the SU(3) flavor symmetry part
is given by a quark-diquark model, and the baryon mass suppression part is
inspired by the string model. We need only eight free parameters to describe
the fragmentation functions for all octet baryons. These free parameters are
determined by a fit to the experimental data of octet baryon production in annihilation. Then we apply the obtained fragmentation functions to
predict the cross section of the octet baryon production in charged lepton DIS
and find consistency with the available experimental data. Furthermore, baryon
production in collisions is suggested to be an ideal domain to check the
predicted mass suppression.Comment: 20 pages, 5 figure
Nonperturbative Corrections to One Gluon Exchange Quark Potentials
The leading nonperturbative QCD corrections to the one gluon exchange
quark-quark, quark-antiquark and pair-excitation potentials are
derived by using a covariant form of nonlocal two-quark and two-gluon vacuum
expectation values. Our numerical calculation indicates that the correction of
quark and gluon condensates to the quark-antiquark potential improves the heavy
quarkonium spectra to some degree.Comment: LaTex, 16 pages, three figures, to appear in Nucl. Phys.
Kahler moduli double inflation
We show that double inflation is naturally realized in K\"ahler moduli
inflation, which is caused by moduli associated with string compactification.
We find that there is a small coupling between the two inflatons which leads to
amplification of perturbations through parametric resonance in the intermediate
stage of double inflation. This results in the appearance of a peak in the
power spectrum of the primordial curvature perturbation. We numerically
calculate the power spectrum and show that the power spectrum can have a peak
on observationally interesing scales. We also compute the TT-spectrum of CMB
based on the power spectrum with a peak and see that it better fits WMAP
7-years data.Comment: 21 pages, 8 figure
NMR Experiments on a Three-Dimensional Vibrofluidized Granular Medium
A three-dimensional granular system fluidized by vertical container
vibrations was studied using pulsed field gradient (PFG) NMR coupled with
one-dimensional magnetic resonance imaging (MRI). The system consisted of
mustard seeds vibrated vertically at 50 Hz, and the number of layers N_ell <= 4
was sufficiently low to achieve a nearly time-independent granular fluid. Using
NMR, the vertical profiles of density and granular temperature were directly
measured, along with the distributions of vertical and horizontal grain
velocities. The velocity distributions showed modest deviations from
Maxwell-Boltzmann statistics, except for the vertical velocity distribution
near the sample bottom which was highly skewed and non-Gaussian. Data taken for
three values of N_ell and two dimensionless accelerations Gamma=15,18 were fit
to a hydrodynamic theory, which successfully models the density and temperature
profiles including a temperature inversion near the free upper surface.Comment: 14 pages, 15 figure
- âŠ