Genetic-algorithm-based simulation optimization considering a single stochastic constraint

In this paper, we consider the discrete optimization via simulation problem with a single stochastic constraint. We present two genetic-algorithm-based algorithms that adopt different sampling rules and searching mechanisms, and thus deliver different statistical guarantees. The first algorithm offers global convergence as the simulation effort goes to infinity. However, the algorithm’s finite-time efficiency may be sacrificed to maintain this theoretically appealing property. We therefore propose the second heuristic algorithm that can take advantage of the desirable mechanics of genetic algorithm, and might be better able to find near-optimal solutions in a reasonable amount of time. Empirical studies are performed to compare the efficiency of the proposed algorithms with other existing ones.     

An efficient curvilinear non‐hydrostatic model for simulating surface water waves

An efficient curvilinear non‐hydrostatic free surface model is developed to simulate surface water waves in horizontally curved boundaries. The generalized curvilinear governing equations are solved by a fractional step method on a rectangular transformed domain. Of importance is to employ a higher order (either quadratic or cubic spline function) integral method for the top‐layer non‐hydrostatic pressure under a staggered grid framework. Model accuracy and efficiency, in terms of required vertical layers, are critically examined on a linear progressive wave case. The model is then applied to simulate waves propagating in a canal with variable widths, cnoidal wave runup around a circular cylinder, and three‐dimensional wave transformation in a circular channel. Overall the results show that the curvilinear non‐hydrostatic model using a few, e.g. 2–4, vertical layers is capable of simulating wave dispersion, diffraction, and reflection due to curved sidewalls. Copyright © 2010 John Wiley & Sons, Ltd.     

Copolyphenylenes with pendant benzimidazolyl and diethanolaminohexyloxy groups: Synthesis and electron‐transporting application in PLEDs

Two new electron‐transporting copolyphenylenes P1NH and P2NH possessing balanced charges crucial to emission efficiency of polymer light‐emitting diodes (PLEDs) have been synthesized and applied as an electron‐transporting layer (ETL). The main chain structure is all para‐linkage for P1NH and both para‐ and meta‐linkage for P2NH , with the same pendant electron‐withdrawing benzimidazolyl and polar diethanolaminohexyloxy groups. Both copolymers possess excellent thermal stability (T _d > 300 °C, T _g > 100 °C) due to their rigid backbones. In addition, the pendant groups effectively lower LUMO (～ ?2.70 eV) and HOMO (～ ?5.70 eV) levels, resulting in improved electron‐transporting and hole‐blocking capabilities. Multilayer yellow‐emitting PLEDs with a configuration of ITO/PEDOT:PSS/SY/ETL/LiF/Al were successfully fabricated by the spin‐coating process. The maximum luminance and maximum current efficiency of the P1NH ‐based device were 12,881 cd/m² and 10.94 cd/A, respectively, superior to the performance of P2NH ‐based device (4938 cd/m², 3.70 cd/A) and the device without ETL (8690 cd/m², 2.78 cd/A). Current results indicate that P1NH is highly effective in enhancing electron transport and device performance. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2494–2505     

Synthesis and characterization of functionalized water soluble cationic poly(ester amide)s

A new family of positively charged, water soluble and functional amino acid‐based poly(ester amide)s ( Arg‐AG PEA ) consisting of four building blocks (L ‐Arginine, DL ‐2‐Allylglycine, oligoethylene glycol, and aliphatic diacid) were synthesized by the solution copolycondensation. Functional pendant carbon–carbon double bonds located in the DL ‐2‐allylglycine unit were incorporated into these Arg‐AG PEAs, and the double bond contents could be adjusted by tuning the feed ratio of L ‐arginine to DL ‐2‐allylglycine monomers. Chemical structures of this new functional Arg‐AG PEA family were confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectra. The thermal property of these polymers was investigated; increasing the methylene chain in both the amino acid and diacid segments resulted in a reduction in the polymer glass‐transition temperature. All these cationic Arg‐AG PEAs had good solubility in water and polar organic solvents. The cytotoxity of Arg‐AG PEAs was evaluated by 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. These preliminary MTT results indicated that Arg‐AG PEAs were nontoxic to bovine aortic endothelial cells (BAECs). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3758–3766, 2010     

Nonisothermal crystallization kinetics of poly(ε‐caprolactone) blocks in double crystalline triblock copolymers containing poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) and poly(ε‐caprolactone) units

The poly(3‐hydroxbutyrate‐co‐3‐hydroxyvalerate)/poly(ε‐caprolactone) block copolymers (PHCLs) with three different weight ratios of PCL blocks (38%, named PHCL‐38; 53%, named PHCL‐53; and 60%, named PHCL‐60) were synthesized by using PHBV with two hydroxyl end groups to initiate ring‐opening polymerization of ε‐caprolactone. During DSC cooling process, melt crystallization of PHCL‐53 at relatively high cooling rates (9, 12, and 15 °C min^?1) and PHCL‐60 at all the selected cooling rates corresponded to PCL blocks so that PHCL‐53 and PHCL‐60 were used to study the nonisothermal crystallization behaviors of PCL blocks. The kinetics of PCL blocks in PHCL‐53 and PHCL‐60 under nonisothermal crystallization conditions were analyzed by Mo equation. Mo equation was successful in describing the nonisothermal crystallization kinetics of PCL blocks in PHCLs. Crystallization activation energy were estimated using Kissinger's method. The results of kinetic parameters showed that both blocks crystallized more difficultly than corresponding homopolymers. With the increase of PCL content, the crystallization rate of PCL block increased gradually. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

A class of nonlinear oscillational systems admitting exact solution of the Fokker-Planck-Kolmogorov equation

It is shown that the Fokker-Planck-Kolmogorov equation in amplitude and phase variables can be reduced to a first-order partial differential equation which admits exact integration for a large class of essentially nonlinear oscillational systems.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 10, pp. 1383–1388, October, 1991.     

Discovery of New Natural Products by Intact‐Cell Mass Spectrometry and LC‐SPE‐NMR: Malbranpyrroles,Novel Polyketides from Thermophilic Fungus Malbranchea sulfurea

Six photosensitive polyketides, malbranpyrroles A–F, were discovered from the thermophilic fungus Malbranchea sulfurea by using intact‐cell desorption/ionization on silicon mass (ICD‐MS) and LC‐SPE‐NMR. These two strategies facilitate the searching and structural determination of unstable natural products. The ICD‐MS indicated that only brown hyphae of M. sulfurea can produce malbranpyrroles. The biosynthetic pathway of malbranpyrroles was evidenced by ¹³C isotope precursors and amino acid feeding experiments. The cytotoxicity data revealed that the conformation of the conjugated system in malbranpyrroles does not affect cytotoxic potency against cancer cell lines. In addition, the chlorine atom was shown to be the pharmacophore for cytotoxicity.     

Spectrally Adjustable Picosecond Dye Laser Pulses Generated with Nanosecond Nitrogen Lasers

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Symplectic Topology of Integrable Hamiltonian Systems, II: Topological Classification

The main purpose of this paper is to give a topological and symplectic classification of completely integrable Hamiltonian systems in terms of characteristic classes and other local and global invariants.     

Fast direct solver for Poisson equation in a 2D elliptical domain

In this article, we extend our previous work 3 for developing some fast Poisson solvers on 2D polar and spherical geometries to an elliptical domain. Instead of solving the equation in an irregular Cartesian geometry, we formulate the equation in elliptical coordinates. The solver relies on representing the solution as a truncated Fourier series, then solving the differential equations of Fourier coefficients by finite difference discretizations. Using a grid by shifting half mesh away from the pole and incorporating the derived numerical boundary value, the difficulty of coordinate singularity can be elevated easily. Unlike the case of 2D disk domain, the present difference equation for each Fourier mode is coupled with its conjugate mode through the numerical boundary value near the pole; thus, those two modes are solved simultaneously. Both second‐ and fourth‐order accurate schemes for Dirichlet and Neumann problems are presented. In particular, the fourth‐order accuracy can be achieved by a three‐point compact stencil which is in contrast to a five‐point long stencil for the disk case. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 72–81, 2004