IDDT Testing versus IDDQ Testing

IDDQ testing has progressed to become a worldwide accepted test method to detect CMOS IC defects. However, it is noticed that observing the average transient current can lead to improvements in real defect coverage, which is referred to IDDT testing. This letter presents a formal procedure to identify IDDT testable faults, and to generate input vector pairs to detect the faults based on Boolean process. It is interesting to note that those faults may not be detected by IDDQ or other test methods, which shows the significance of IDDT testing.     

电子地图的可视化与空间分析

阐述了电子地图的特点，并对电子地图的数据获取，数据结构，空间分析和可视化技术进行了分析。     

多级多层复合滑坡工程病害的试验研究

张家坪滑坡具有多级多层的复杂滑体结构,本文选取最典型的断面开展了大型地质力学模型试验,模拟了边坡的开挖过程,并采用均匀毛细浸润技术研究雨水作用下的坡体稳定性,通过有无支挡的两阶段试验对比,分析了多级多层复合滑坡的变形失稳机制和工程病害,以及相应抗滑支挡结构的加固效果。     

Boundary element analysis for elastic and elastoplastic problems of 2D orthotropic media with stress concentration

Both the orthotropy and the stress concentration are common issues in modern structural engineering. This paper introduces the boundary element method (BEM) into the elastic and elastoplastic analyses for 2D orthotropic media with stress concentration. The discretized boundary element formulations are established, and the stress formulae as well as the fundamental solutions are derived in matrix notations. The numerical procedures are proposed to analyze both elastic and elastoplastic problems of 2D orthotropic media with stress concentration. To obtain more precise stress values with fewer elements, the quadratic isoparametric element formulation is adopted in the boundary discretization and numerical procedures. Numerical examples show that there are significant stress concentrations and different elastoplastic behaviors in some orthotropic media, and some of the computational results are compared with other solutions. Good agreements are also observed, which demonstrates the efficiency and reliability of the present BEM in the stress concentration analysis for orthotropic media. The project supported by the Basic Research Foundation of Tsinghua University, the National Foundation for Excellent Doctoral Thesis (200025) and the National Natural Science Foundation of China (19902007). The English text was polished by Keren Wang.     

可溶性有机质对污染土壤中铊迁移行为的影响

目的 为了查明可溶性有机质（DOM）对土壤中污染元素铊赋存形态的影响,方法 采用形态分级提取方法,将土壤中的铊重金属分成酸可交换态、铁锰氧化物结合态、有机质结合态和残留态4组分,并采用Elan 6100型ICP-MS质谱仪测定各组分中铊的质量浓度.结果 DOM可降低酸可交换态的Tl,增加铁锰氧化物结合态和有机质结合态Tl的百分含量,但对残留态Tl的百分含量没有明显影响.因此,DOM可降低铊在土壤中的活动性,从而改变了铊在土壤中的迁移行为.结论 可溶性有机质（DOM）自身的络合（螯合）能力及其吸附特性是改变重金属铊形态分布的主要因素.     

一种新型钼钒酸盐的合成、结构和磁性表征

用水热方法合成了一个新型的钼钒多金属氧酸盐[PⅤMoⅥ7MoⅤVⅣ8O44][Ni(Phen)2OH]4·3H2O(1),用元素分析、红外光谱和X射线单晶衍射等技术手段对化合物的晶体结构进行了表征。结果表明,该化合物属于三斜晶系,P-1空间群,a=1.51300(11)nm,b=1.74813(15)nm,c=2.58896(18)nm,α=72.842(4)°,β=89.240(5)°,γ=72.627(5)°,V=6.2233(8)nm3,Z=1,R1=0.0962,wR2=0.2572。化合物是高还原态的四帽α-Keggin结构钼钒多金属氧簇,通过簇阴离子4个钒帽上的端氧分别支撑4个镍过渡金属配合物,形成一个中性的多金属氧酸盐。多金属氧簇上的端氧与结晶水分子之间的强烈氢键使化合物形成了三维超分子结构。     

A SOLUTION PROCEDURE FOR LOWER BOUND LIMIT AND SHAKEDOWN ANALYSIS BY SGBEM

The symmetric Galerkin boundary element method (SGBEM) instead of the finite element method is used to perform lower bound limit and shakedown analysis of structures. The self-equilibrium stress fields are constructed by a linear combination of several basic self-equilibrium stress fields with parameters to be determined. These basic self-equilibrium stress fields are expressed as elastic responses of the body to imposed permanent strains and obtained through elastic-plastic incremental analysis. The complex method is used to solve nonlinear programming and determine the maximal load amplifier. The limit analysis is treated as a special case of shakedown analysis in which only the proportional loading is considered. The numerical results show that SGBEM is efficient and accurate for solving limit and shakedown analysis problems. Project supported by the National Natural Science Foundation of China (No. 19902007), the National Foundation for Excellent Doctorial Dissertation of China (No. 200025) and the Basic Research Foundation of Tsinghua University.     

Target models for range performance prediction of infrared imaging system

This paper describes a commonly used target model and two improved models for range performance prediction of infrared imaging system in an original explicit way. We conclude the basic assumptions of each model, define the temperature difference, and give the mathematical equation to calculate the measurement of resolvable target details. The flow path for using the measurement to evaluate the range performance is briefly introduced. The features of these models are compared.     

射线跟踪法对室内MIMO信道容量分析

采用确定性传播预测模型——2维射线跟踪法分析了室内非视距传播环境中MIMO系统容量ccdfs。分析结果表明,在非视距的室内环境中实现MIMO系统容量增益所需要的散射环境是丰富的,天线阵的阵列结构如天线间隔是影响MIMO系统的主要因素。当天线之间的间隔为5λ时,MIMO 系统的容量非常接近Telatar分析的独立同分布瑞利信道容量。但当天线之间的间隔为0.5λ时,MIMO 系统容量显著降低,并且随着天线数目的增加,容量降低越显著。