D—Wave Kondo Problem in a Square Tight—Bounding Lattice

A Kondo model in a square tight-bonding lattice of conduction electrons is considered.The Kondo interaction takes a d-wave.Using mean-field theory and numerical simulations,it is found that there is a pseudo-gap for the impurity density of states at the Fermi level.Numerical results also show that the exponents of the lowtemperature thermodynamic quantities are non-universal but dependent on the interaction.     

NUMERICAL ANALYSIS OF QUASICONFORMAL MAPPINGS BY CIRCLE PACKINGS

Thurston proposed that conformal mappings can be approximated by circle packing isomorphisms and the approach can be implemented efficiently. Based on the circle packing methods the rate of convergence of approximating solutions for quasiconformai mappings in the plane is discussed.     

日本大学“数字感受舆心算”调查情况

据《全国珠算新闻》（日本珠连主办）２００２年５月号报道：今年二月，日本珠算教育连盟以首都及近郊的工科院校和科院校二百名学生为对象，进行了关于“数字感觉与心算”的调查。     

从电子器件的换代来看计算机的发展

 电子计算机的诞生与发展,极大地推进了现代科学技术的发展。从第一台计算机诞生到今天,计算机已经历了四代,而四代机的划分是以电子器件的换代为主体特征。电子管的发明和第一代电子管数字计算机（1946～1958年）1883年,美国发明家爱迪生（T.A.Edison,1847～1931）发现了热的灯丝发射电荷的现象,并被称之为“爱迪生效应”。1889年,英国著名物理学家汤姆孙（J.J.Thomson,1856～1940）解释了这种现象,并把带电的粒子称为“电子”,同年,英国伦敦大学电工学教授弗莱明（S.J.A.Fleming,1849～1945）开始认真研究爱迪生效应,并且于1904年研制出检测电波用的     

科学计算用数字电子计算机的若干问题

数字电子计算机的发明与发展的主要动力是大型科学计算.计算机是应科学计算的需要而发明的,应科学计算的不断追求而迅速发展的.科学计算课题的要求是无限的,而计算机的解题能力是有限的,装备计算机的技术也是有限的.因此如何处处“节约”技术,最“经济”地使用技术,以当前有限的技术研制出计算能力尽可能大的计算机是科学计算工作者很关心的问题.     

数海星空——神奇的20阶数学迷宫图

今年是明代珠算大师程大位逝世400周年，为了纪念这位珠算大师对于民族文化——珠算所做出的杰出贡献，特此编写20阶数学迷宫图，以数字世界的奥妙来展示珠算文化的无穷魅力。     

基于TMS320C5410EVM板的IIR数字滤波器的设计

本文研究DSP中的IIR数字滤波器的原理和用MATLAB在TMS320C5410EVM中设计IIR数字滤波器的过程和设计方法以及程序的调试方法。     

传输线中脉冲信号反射波的测量和应用

将高频单脉冲信号输入同轴电缆，借助数字存储示波器记录输入、输出端的波形和相对延时，可以测量传输线的电缆长度和衰减系数，同时观察脉冲波形因色散引起的畸变．     

Damage and fracture evaluation of granular composite materials by digital image correlation method

This paper presents the applications of digital image correlation technique to the mesoscopic damage and fracture study of some granular based composite materials including steelfiber reinforced concrete, sandstone and crystal-polymer composite. The deformation fields of the composite materials resulted from stress localization were obtained by the correlation computation of the surface images with loading steps and thus the related damage prediction and fracture parameters were evaluated. The correlation searching could be performed either directly based on the gray levels of the digital images or from the wavelet transform (WT) coefficients of the transform spectrum. The latter was developed by the authors and showed higher resolution and sensitivity to the singularity detection. Because the displacement components came from the rough surfaces of the composite materials without any coats of gratings or fringes of optical interferometry, both surface profiles and the deformation fields of the composites were visualized which was helpful to compare each other to analyze the damage of those heterogeneous materials. The project supported by the National Natural Science Foundation of China (10125211 and 10072002), the Scientific Committee of Yunnan Province for the Program of Steel Fiber Reinforced Concrete, and the Institute of Chemical Materials, CAEP at Mianyang     

Evolution of Spiral Waves under Modulated Electric Fields

Spirals generated from the excitable media within the Barkley model is investigated under the gradient electric fields by a numerical simulation. The spiral drift and spiral break up are observed when the amplitude of the electric fields is modulated by a constant signal or a chaotic signal. It is also verified that, even in the presence of the white noise, the whole system can reach homogeneous states after the spiral breakup, by using an adaptive strategy.