A multi-agent based evolutionary algorithm in non-stationary environments

This article is posted here with permission of IEEE - Copyright @ 2008 IEEEIn this paper, a multi-agent based evolutionary algorithm (MAEA) is introduced to solve dynamic optimization problems. The agents simulate living organism features and co-evolve to find optimum. All agents live in a lattice like environment, where each agent is fixed on a lattice point. In order to increase the energy, agents can compete with their neighbors and can also acquire knowledge based on statistic information. In order to maintain the diversity of the population, the random immigrants and adaptive primal dual mapping schemes are used. Simulation experiments on a set of dynamic benchmark problems show that MAEA can obtain a better performance in non-stationary environments in comparison with several peer genetic algorithms.This work was suported by the Key Program of National Natural Science Foundation of China under Grant No. 70431003, the Science Fund for Creative Research Group of the National Natural Science Foundation of China under Grant No. 60521003, the National Science and Technology Support Plan of China under Grant No. 2006BAH02A09, and the Engineering and Physical Sciences Research Council of the United Kingdom under Grant No. EP/E060722/1

Quasifinite representations of classical Lie subalgebras of W_{1+infty}

We show that there are precisely two, up to conjugation, anti-involutions sigma_{\pm} of the algebra of differential operators on the circle preserving the principal gradation. We classify the irreducible quasifinite highest weight representations of the central extension \hat{D}^{\pm} of the Lie subalgebra of this algebra fixed by - sigma_{\pm}, and find the unitary ones. We realize them in terms of highest weight representations of the central extension of the Lie algebra of infinite matrices with finitely many non-zero diagonals over the truncated polynomial algebra C[u] / (u^{m+1}) and its classical Lie subalgebras of B, C and D types. Character formulas for positive primitive representations of \hat{D}^{\pm} (including all the unitary ones) are obtained. We also realize a class of primitive representations of \hat{D}^{\pm} in terms of free fields and establish a number of duality results between these primitive representations and finite-dimensional irreducible representations of finite-dimensional Lie groups and supergroups. We show that the vacuum module V_c of \hat{D}^+ carries a vertex algebra structure and establish a relationship between V_c for half-integral central charge c and W-algebras.Comment: Latex, 77 page

Antecedents of Voluntary Corporate Governance Disclosure: A Post-2007/08 Financial Crisis Evidence from the Influential UK Combined Code

Purpose: This study investigates the level of compliance with, and disclosure of, good corporate governance (CG) practices among UK publicly listed firms, and consequently ascertains whether board characteristics and ownership structure variables can explain observable differences in the extent of voluntary CG compliance and disclosure practices. Design/Methodology/Approach: The study uses one of the largest datasets to-date on compliance and disclosure of CG practices from 2008 to 2013 containing 120 CG provisions drawn from the 2010 UK Combined Code relating to 100 UK listed firms to conduct multiple regression analyses of the determinants of voluntary CG disclosures. A number of additional estimations, including two stage least squares, fixed-effects and lagged structures, are conducted in order to test the robustness of the findings. Findings: The results suggest that there is a substantial variation in the levels of compliance with, and disclosure of, good CG practices among the sampled UK firms. We also find that firms with larger board size, more independent outside directors and greater director diversity tend to disclose more CG information voluntarily, whereas the level of voluntary CG compliance and disclosure is insignificantly related to the existence of a separate CG committee and institutional ownership. Additionally, the results indicate that block ownership and managerial ownership impact negatively on voluntary CG compliance and disclosure practices. The findings are fairly robust across a number of econometric models that sufficiently address various endogeneity problems and alternative CG indices. Overall, the findings are generally consistent with the predictions of neo-institutional theory. Originality/Value: This paper extends, as well as contributes to the extant CG literature by offering new evidence on compliance with, and disclosure of, good CG recommendations contained in the 2010 UK Combined Code following the 2007/08 global financial crisis. This paper also advances the existing literature by offering new insights from a neo-institutional theoretical perspective of the impact of board and ownership mechanisms on voluntary CG compliance and disclosure practices. Keywords: Corporate governance; Board and ownership mechanisms; Comply or explain; Neo-institutional theory; UK Combined Cod

The Ohio State 1991 geopotential and sea surface topography harmonic coefficient models

The computation is described of a geopotential model to deg 360, a sea surface topography model to deg 10/15, and adjusted Geosat orbits for the first year of the exact repeat mission (ERM). This study started from the GEM-T2 potential coefficient model and it's error covariance matrix and Geosat orbits (for 22 ERMs) computed by Haines et al. using the GEM-T2 model. The first step followed the general procedures which use a radial orbit error theory originally developed by English. The Geosat data was processed to find corrections to the a priori geopotential model, corrections to a radial orbit error model for 76 Geosat arcs, and coefficients of a harmonic representation of the sea surface topography. The second stage of the analysis took place by doing a combination of the GEM-T2 coefficients with 30 deg gravity data derived from surface gravity data and anomalies obtained from altimeter data. The analysis has shown how a high degree spherical harmonic model can be determined combining the best aspects of two different analysis techniques. The error analysis was described that has led to the accuracy estimates for all the coefficients to deg 360. Significant work is needed to improve the modeling effort

Insuring Rural China's Health? An Empirical Analysis of China's New Cooperative Medical System

Although health is an important factor in economic development, millions of China's rural residents have no medical coverage. Nearly 10 percent of those that were sick in rural China consciously did not seek medical care, mostly because of financial constraints. More than 25% of rural residents are dissatisfied with their village's health system. In response to this deteriorating situation, a new cooperative medical system (NCMS) was initialized in rural China in 2003 by the government. However, after two years of trials, there has been no household-based, economic analysis of the program. This paper provides one of the first. Although where introduced, most rural residents voluntarily participate, there are many problems with the program. First, at least in its initial years, targeting has been poor; the program has been adopted in richer villages, even though there is a case that there are higher medical needs in poorer villages. Also, while the government subsidy pays part of the premium, more than 40% criticize the design of the program, including complaints about coverage, reimbursement rates and procedures. Based on our survey, the major concern is the extremely low reimbursement rates. Instead of up to 30% as promised, only 3% of total medical expenses of program participants were paid (6% for inpatient expenses). The expected payout of a participating farmer is actually negative; the farmer receives back less than what he/she puts in. There also is a gap in understanding of farmers and clinicians between the actual implementation of reimbursements and policy.Rural Health, Insurance, Targeting, Design Problems, China, Health Economics and Policy, I11, O15, O53,

Weak coupling d-wave BCS superconductivity and unpaired electrons in overdoped La_{2-x}Sr_{x}CuO_{4} single crystals

The low-temperature specific heat (SH) of overdoped La_{2-x}Sr_{x}CuO_{4} single crystals (0.178=<x=<0.290) has been measured. For the superconducting samples (0.178=<x=<0.238), the derived gap values (without any adjusting parameters) approach closely onto the theoretical prediction \Delta_{0}=2.14k_{B}T_{c} for the weak-coupling d-wave BCS superconductivity. In addition, the residual term \gamma(0) of SH at H=0 increases with x dramatically when beyond x~0.22, and finally evolves into the value of a complete normal metallic state at higher doping levels, indicating growing amount of unpaired electrons. We argue that this large \gamma(0) cannot be simply attributed to the pair breaking induced by the impurity scattering, instead the phase separation is possible.Comment: 6 pages, 6 figures; Contents added; Accepted for publication in Phys. Rev.

Two dimensional scaling of resistance in flux flow region in Tl2Ba2CaCu2O8Tl_2Ba_2CaCu_2O_8 thin films

The resistance of $Tl_2Ba_2CaCu_2O_8$ thin films has been measured when the angle between the applied fields and $ab$-plane of the film is changed continuously at various temperatures. Under various magnetic fields, the resistance can be well scaled in terms of the c-axis component of the applied fields at the same temperature in the whole angle range. Meanwhile, we show that the measurement of resistance in this way is a complementary method to determine the growth orientation of the anisotropic high-$T_c$ superconductors.Comment: 11 pages, 8 figures. Have been published in Physica