X分形晶格上Gauss模型的临界性质

采用实空间重整化群变换的方法,研究了2维和d(d>2)维X分形晶格上Gauss模型的临界性质.结果表明:这种晶格与其他分形晶格一样,在临界点处,其最近邻相互作用参量也可以表示为K=bqiqi(qi是格点i的配位数,bqi是格点i上自旋取值的Gauss分布常数)的形式;其关联长度临界指数v与空间维数d(或分形维数df)有关.这与Ising模型的结果存在很大的差异. 关键词： X分形晶格 重整化群 Gauss模型 临界性质     

一个电磁感应佯谬及其理论分析

提出一个令人困惑的电磁感应问题，并运用电磁学理论对其进行了详尽的理论分析。     

NO-2-I-体系双波长紫外分光光度法测定痕量亚硝酸根

在稀盐酸介质中,亚硝酸根氧化碘化钾的反应产物I-3在288nm和352nm处有两个强吸收峰.基于此建立了双波长紫外分光光度法测定痕量NO-2的新方法.该法简便、快速、选择性好,线性范围为0-0.4μg/mL,检出限为3.4×10-9g/mL.用于河水、井水、矿泉水中亚硝酸根的测定,结果令人满意.     

Controlling global stochasticity of Hamiltonian systems by nonlinear perturbation

A method of controlling global stochasticity in Hamiltonian systems by applying nonlinear perturbation is proposed. With the well-known standard map we demonstrate that this control method can convert global stochasticity into regular motion in a wide chaotic region for arbitrary initial condition, in which the control signal remains very weak after a few kicks. The system in which chaos has been controlled approximates to the original Hamiltonian system, and this approach appears robust against small external noise. The mechanism underlying this high control efficiency is intuitively explained. Received 15 January 2002 Published online 6 June 2002     

Liquid phase oxidation of p-chlorotoluene to p-chlorobenzaldehyde over cobalt-doped mesoporous titania with a crystalline framework

Cobalt-doped mesoporous titania with a crystalline framework synthesized by surfactant templating method presented highly selective (99%) and reasonable conversion rate (49%) of catalytic oxidation of para-chlorotoluene to para-chlorobenzaldehyde in acetic acid using aqueous hydrogen peroxide as oxidant for the first time. Recycling of the catalyst indicates that the catalyst can be used a number of times without losing its activity to a greater extent. By contrast, cobalt-doped mesoporous titania without a crystalline structure and cobalt doped the commercial titania, Degussa P25 prepared by impregnation method with the similar concentration of cobalt were found inactive. The effects of catalyst concentration, reaction time, reaction temperature, and solvents on the performance of the catalyst were also investigated.     

MODIS通道1和通道2大气订正的一种快速实用方法

提出了利用气象资料对MODIS影像进行大气校正的一种快速实用方法.读取MODIS前两个通道250min的反射率,采用常用的黑色目标扣除法(Dark-object subtraction)计算天空程辐射,通过卫星过境时刻的气象能见度和水汽资料计算大气透过率,最后推导出目标物的反射率.通过比较两个邻近日期MODIS影像校正前后的归一化植被指数(NDVI)值,得出利用本文提出的方法对MODIS进行大气校正所得到的NDVI值更接近实际情况.结果表明:利用气象能见度和水汽压可以对MODIS数据进行快速有效的大气校正.     

Compact, reliable asymmetric optical configuration for cost-effective fabrication of multiplex dot matrix hologram in anti-counterfeiting applications

This study presents a compact optical configuration that can generate a multiplex dot-matrix hologram with complex interlaced images for anti-counterfeiting applications on valuable paper. Varying the orientation of the interference plane can enable the multiplex hologram to be recorded without changing the interference angle of two laser beams. With its simple asymmetric optical setup, a multiplex hologram with many interlaced images can be efficiently fabricated, increasing the cost of imitation. Experimental details of the asymmetric optical setup are also described.     

某轴流压气机叶尖间隙效应实验研究

本文对某低速轴流压气机叶尖间隙尺度对性能的影响进行了实验研究,并通过不同的机匣结构情况研究一种叶尖漏流不敏感机匣。实验表明,不同的间隙尺度对叶轮机总体性能存在十分明显的影响。对绝大部分运行状态,小间隙下的压升和效率均明显高于大间隙的情况。另外,所采用的毛刷式和篦齿式的机匣实验结果表明,不论毛刷式还是篦齿式机匣,在大流量负攻角情况下对性能的影响不大,但毛刷式机匣并不能达到提高失速裕度的目的,而篦齿式机匣在小流量情况下对压升有所提高,但对效率影响不大。     

The Synthesis of Glycoglycerolipids

A convenient synthetic route was developed for the synthesis of the novel glycolipids: 1,2-di-O-acyl-3-O-(2‘-acylamide-2‘-denxy-ct-D-glucopyranosyl)-sn-glycerols. 10 new compounds of glycolipids with different acyl groups were obtained.     

用数值方法分析微孔激光器出射光的近场特性

微孔激光器作为应用于近场光信息存储系统中的一种新型光源，它的出射光斑的近场特性对于近场光存储是十分重要的。针对纳米孔径运用角谱进行Fox-Li数值迭代，得到不同孔径微孔激光器的基模光强分布，然后运用二维非线性时域有限差分法分析微孔激光器出射端即微孔金属膜的近场光学性质，模拟计算了不同孔径和厚度的微孔金属膜的光强近场分布，从应用于近场光存储的角度，给出反映其近场光学特性的相关数据。发现由于TM模式下金属存在局域表面等离子增强效应，使得其出射强度比TE模式高一个数量级，从而更适于作为实际中近场光存储系统和原理试验的光学头。