Genetic algorithms with shrinking population size

A Genetic Algorithm (GA) is an evolutionary computation technique inspired by the principle of biological evolution via natural selection. It employs the fundamental components of evolution, such as selection, mating, and mutation, which continue from generation to generation, creating better solutions as time progresses. Although it is mostly used as an optimization tool, GA enjoys a wide spectrum of applications in diverse fields such as engineering, medicine, and ecology, among others. In this study, we propose three different population size reduction methods for a typical GA optimization, aiming to increase efficiency. Additionally, we compare the accuracy and precision of these methods using Monte Carlo simulations.     

Adsorption and diffusion of argon in disordered nanoporous carbons

Application-specific optimization of disordered nanoporous carbons remains a formidable challenge due to the difficulty in accurately characterizing their microstructures with current empirical methods. Using molecular simulation techniques, we investigated the adsorptive and diffusive behavior of argon in three models of disordered nanoporous carbons. We found that the structural and morphological differences between these models gave rise to distinct phenomenological properties. The adsorptive behavior of argon in both the low and high pressure regimes was enhanced dramatically in the models with more crystalline microstructures. As for dynamic properties, we found that the adsorbent’s structure and energetic topology significantly alters the rates of diffusion as well as the characteristics of the underlying diffusion mechanisms.     

Using an iterative linear solver in an interior-point method for generating support vector machines

This paper concerns the generation of support vector machine classifiers for solving the pattern recognition problem in machine learning. A method is proposed based on interior-point methods for convex quadratic programming. This interior-point method uses a linear preconditioned conjugate gradient method with a novel preconditioner to compute each iteration from the previous. An implementation is developed by adapting the object-oriented package OOQP to the problem structure. Numerical results are provided, and computational experience is discussed.     

A recyclable chiral Ru catalyst for enantioselective olefin metathesis. Efficient catalytic asymmetric ring-opening/cross metathesis in air

The synthesis and structure of a new chiral bidentate imidazolinylidene ligand and a derived chiral Ru-based carbene are disclosed. The Ru complex is stereogenic at the metal center; it can be prepared in >98% diastereoselectivity and purified by silica gel chromatography with undistilled solvents. The air-stable Ru complex efficiently catalyzes ring-closing and ring-opening metathesis and is recyclable. The chiral complex is highly effective (0.5-10 mol % loading) in promoting enantioselective ring-opening/cross metathesis reactions (up to >98% ee). These enantioselective transformations can be effected in air, with unpurified solvent and with substrates that would only polymerize with Mo-based catalysts.     

Study of an ultrahigh-numerical-aperture fiber continuum generation source for optical coherence tomography

The axial resolution of optical coherence tomography images is primarily dependent on the bandwidth of the illumination source. Continuum generation is one way to generate the single-mode, high-bandwidth light needed for point illumination. We present an inexpensive and easy-to-implement augmentation to a Ti:sapphire laser that widens the bandwidth from 20 to over 200 nm with commerically available ultrahigh-numerical-aperture fiber. This technique can provide a readily available broad-bandwidth source for researchers and a practical enhancement to a fiber-optic optical coherence tomography system.     

Gram-scale synthesis of (+)-discodermolide

[formula: see text] A triply convergent, highly efficient second-generation synthesis of the potent antimitotic agent (+)-discodermolide (1) has been achieved on a 1-g scale.     

Equivariant Riemann–Roch for G ‐Quasi‐Projective Varieties‐I

Let G denote a complex linear algebraic group. In this paper we establish several forms of equivariant Riemann–Roch valid for the category of Gquasiprojective complex varieties. The main application is to the operation of convolution that appears in the construction of modules over convolution algebras, for example the Hecke algebras associated to a complex reductive group as well as in the representation theory of quantum groups. The paper concludes with a discussion of some of these applications. The results in this paper hold mostly at the level of Grothendieck groups. The second part of this paper will discuss the extension to higher Ktheory in detail.     

Kinetics of the reaction Cl + CH4 → CH3+ HCl from 200° to 500deg;K

The rate constant for the reaction \documentclass{article}\pagestyle{empty}\begin{document}${\rm Cl} + {\rm CH}_4 \mathop {\longrightarrow}\limits^1 {\rm CH}_3 + {\rm HCl}$\end{document} has been determined over the temperature range of 200°–500°K using a discharge flow system with resonance fluorescence detection of atomic chlorine under conditions of large excess CH₄. For 300° > T > 200°K the data are best fitted to the expression k₁ = (8.2 ± 0.6) × 10^?12 exp[?(1320 ± 20)/T] cm³/sec. Curvature is observed in the Arrhenius plot such that the effective activation energy increases from 2.6 kcal/mol at 200° < T < 300°K to 3.5 kcal/mol at 360° < T < 500°K. The data over the entire range may be fitted by the expression k₁ = 8.6×10^?18 T^2.11 exp[?795/T]. These results are compared with other experimental studies and with a semiempirical transition state calculation. Their atmospheric significance is discussed.