Second Harmonic Generation in Bis Typed Organic Compounds

In systematic research on a series of new nonlinear organic materials, we found that Bis (4-nitrophenoxy) methane (BNPM) showed a large intensity of second harmonic light, which was 4.4 times as large as that of urea crystal by powder technique and easily crystallized from a solution. The crystal structure of BNPM, obtained by the X-ray diffraction method, was orthorhombic, space group P2₁2₁2 (point group 222), with unit-sell dimension a = 10.205 Å; b = 12.854 Å; c = 4.8822 Å. In addition, we found that the absorption edge of BNPM was 430 nm with a 0.9-mm-thick crystal, and we observed the second harmonic light with BNPM single crystal at the wavelength of 1064 nm and in the range from 906 nm to 990 nm.     

在环形理想导体空腔中极向线电流产生的磁场

本文研究在环形理想导体空腔中极向线电流产生的磁场。在一级环形效应近似下得到的理论结果，基本上与实验数据一致，并且可以推广使用到具有一定类型极向电流分布的情况。     

聚苯乙烯芪盐L—B膜的二阶非线性光学性质研究

首次合成了一种称之为聚苯乙烯芪盐的有机高分子材料.此材料可以在水面上形成稳定的单分子层膜,并且所形成的单分子层膜可以转移到固体衬底上去.对聚苯乙烯芪盐单分子层膜进行光学二次谐波产生测量,得到聚苯乙烯芪盐对应于每个发色团的二阶非线性极化率为1.2×10~(-28)esu.制备了该材料两种不同类型的多层膜,讨论了多层膜二次谐波产生信号不随层数增加而增加的可能原因.     

A Mixed Heuristic for Circuit Partitioning

As general-purpose parallel computers are increasingly being used to speed up different VLSI applications, the development of parallel algorithms for circuit testing, logic minimization and simulation, HDL-based synthesis, etc. is currently a field of increasing research activity. This paper describes a circuit partitioning algorithm which mixes Simulated Annealing (SA) and Tabu Search (TS) heuristics. The goal of such an algorithm is to obtain a balanced distribution of the target circuit among the processors of the multicomputer allowing a parallel CAD application for Test Pattern Generation to provide good efficiency. The results obtained indicate that the proposed algorithm outperforms both a pure Simulated Annealing and a Tabu Search. Moreover, the usefulness of the algorithm in providing a balanced workload distribution is demonstrated by the efficiency results obtained by a topological partitioning parallel test-pattern generator in which the proposed algorithm has been included. An extented algorithm that works with general graphs to compare our approach with other state of the art algorithms has been also included.     

Min-cut clustering

We describe a decomposition framework and a column generation scheme for solving a min-cut clustering problem. The subproblem to generate additional columns is itself an NP-hard mixed integer programming problem. We discuss strong valid inequalities for the subproblem and describe some efficient solution strategies. Computational results on compiler construction problems are reported.This paper is dedicated to Phil Wolfe on the occasion of his 65th birthday.This research was supported by NSF grants DMS-8719128 and DDM-9115768, and by an IBM grant to the Computational Optimization Center, Georgia Institute of Technology.     

Optical mm-wave generation by using external modulator based on optical carrier suppression

In this paper, we have theoretically investigated the transmission performance of the optical millimeter (mm)-wave generated by using an external modulator based on optical carrier suppression for the first time. According to our theory, the data signals carried by the optical mm-wave are transmitted in the dispersion fiber without fading but are degraded greatly because of the time shift of the code edges, which still limits the transmission distance. The experimental results agree well with our theory.     

Magnetotropicity of five-membered heterocyclic molecules

Ab initio methods have been employed to obtain models for the current density field induced in the electrons of pentatomic cyclic molecules C₄H₄X, with X = CH₂, NH, O, S, PH, and AsH, in the presence of a static, homogeneous magnetic field normal to the plane containing the four ring carbon atoms. These models are expected to provide simple and valid tools to assess the magnetotropism of these compounds and to interpret their magnetic response.     

Phase-matched second-harmonic generation in poled polymer waveguide based on a main chain polymer

The electric field-induced dynamic phase-matching of second harmonic generation (SHG) waveguide was demonstrated by using a main chain polyarylamine. The linear and nonlinear optical properties of this polymer are presented. The optimum phase-matching thickness was controlled by applying an electric field to the polymer waveguide. The effective phase-matching thickness variation induced by poling is about 0.025 μm that is six times larger than full width at the half-maximum (FWHM) of phase-matching thickness in conventional slab waveguide. The efficient phase-matched SHG was observed from a taperless slab wave-guide. The optical loss of poled polymer on glass substrate at 632.8 nm was 2.7 dB/cm. © 1995 John Wiley & Sons, Inc.     

Effects of Hall current on f lows of a Burgers’ fluid through a porous medium

This paper generalizes the analysis of four magnetohydrodynamic (MHD) flow problems of an Oldroyd-B fluid discussed by Asghar et al. [Int. J. Non-linear Mech. 40, 589–601 (2005)] into three directions: (i) to discuss the problems in a porous medium using modified Darcy’s law (ii) to see the influence of Hall current (iii) to determine the effect of rheological parameter of Burgers’ fluid. Analytical solutions of velocity distribution valid at large and small times are given in each problem. Comparison has been provided for Oldroyd-B and Burgers’ fluids through graphs. The physical interpretation is also included.     

Accelerating column generation for variable sized bin-packing problems

In this paper, we study different strategies to stabilize and accelerate the column generation method, when it is applied specifically to the variable sized bin-packing problem, or to its cutting stock counterpart, the multiple length cutting stock problem. Many of the algorithms for these problems discussed in the literature rely on column generation, processes that are known to converge slowly due to primal degeneracy and the excessive oscillations of the dual variables. In the sequel, we introduce new dual-optimal inequalities, and explore the principle of model aggregation as an alternative way of controlling the progress of the dual variables. Two algorithms based on aggregation are proposed. The first one relies on a row aggregated LP, while the second one solves iteratively sequences of doubly aggregated models. Working with these approximations, in the various stages of an iterative solution process, has proven to be an effective way of achieving faster convergence.