Comparison of corrosion behavior of zirconium bombarded with self-ion and molybdenum ion

In order to study the effects of zirconium and molybdenum ion bombardment on the aqueous corrosion behavior of zirconium, one group of specimens was implanted with zirconium ions with ions surface densities ranging from 1 × 10¹⁵ to 2 × 10¹⁷ ions/cm² at about 170 °C, using a metal vapor vacuum arc (MEVVA) source operated at an extraction voltage of 50 kV. The other group of specimens was bombarded with molybdenum ion with ions surface densities ranging from 1 × 10¹⁶ to 5 × 10¹⁷ ions/cm² at about 160 °C, using a MEVVA source operated at an extraction voltage of 40 kV. The valence states and depth distribution of elements in the surface of the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), respectively. Polarization curves measurement was employed to evaluate the aqueous corrosion resistance of the zirconium samples in a 1N H₂SO₄ solution. It was found that the aqueous corrosion resistance of zirconium implanted with 5 × 10¹⁶ Zr ions/cm² is the best in first group samples. For molybdenum ion implantation, the aqueous corrosion resistance of samples declined with raising ions surface densities. The natural corrosion potentials of zirconium samples bombarded with self-ions are more negative than that of the as-received zirconium. While, as for molybdenum ion implantation, the results are opposite. Finally, the mechanisms of the corrosion behavior of the zirconium samples implanted with zirconium and molybdenum ions are discussed.     

混凝土斜裂纹损伤断裂分析

混凝土构件中宏观裂纹尖端附近，伴随有损伤，随着损伤的发展，微裂纹集度不断增大，合并形成宏观裂纹，本文将Mazars混凝土损伤模型应用于混凝土断裂分析中，带斜裂纹的构件受拉应力作用时，将产生Ⅰ、Ⅱ型复合裂纹．本文分析了宏观裂纹尖端附近区域的损伤，所得结果与最大拉应力理论的结果比较相符。     

轴流式鼓风机静叶承缸事故原因分析

对AV80—14型轴流式鼓风机的静叶承缸受损的原因进行了分析，对受损的静叶承缸的修复过程进行了介绍。通过对事故承缸进行变形校正和裂纹修复，使受损静叶承缸起死回生，节约备件购置费用200万元以上。     

提高氧化铝熟料回转窑内衬使用寿命的措施

分析了氧化铝熟料窑内衬的损毁原因，按照提高耐火材料性能，划分区域分类使用，满足工矿条件的宗旨，从使用、砌筑、操作三方面采取改进措施，使熟料窑内衬的平均使用寿命提高了1．5～1．8倍，取得了显著的经济效益。     

Reconnaissance of Golcuk 1999 Earthquake Damage Using Satellite Images

This study utilizes remotely sensed pre- and post-disaster images in order to detect any change specifically associated with structural and major regional damage caused by natural disasters such as a strong earthquake. Currently, postdisaster reconnaissance is conducted using mostly ground-truth teams. Although by using this method high-resolution assessment can be provided, it is very time consuming, costly and sometimes not practical. This study investigates an unsupervised near near-time method of reconnaissance using a pair of coregistered remotely sensed images of the same scene acquired at different times as input. The output is an image (mostly binary) in which “changed” pixels are separated from “not-changed” ones. The approach is fully deterministic using principal component analysis, normalization and further setting a threshold to classify pixels. For verification, a set of multispectral images from Golcuk-Turkey 1999 earthquake was used. It is concluded the program generates very similar results as obtained by ground-truth teams.     

神经网络在结构损伤模拟中的应用

识别一个结构在震动状态下的变化，在结构监测中是十分重要的，神经网络就非常适用于这种目的。本文研究了使用可分析的学习样本来训练神经网络的可行性问题。神经网络从损伤状态中训练产生，然后用于诊断一个五层钢框架在一系列震动模拟中的状态。结果表明，使用神经网络可使在线结构诊断更加可行。     

水泥砂浆的率型损伤演化

实验结果表明,水泥砂浆在受力变形中的损伤演化是率相关的,因此,类似于位错运动的热激活机制;给出了水泥砂浆的率型损伤演化律．     

夹杂物问题应力场的数值计算

等效夹杂物方法是细观力学中的一种重要方法，文中编制的数值计算程序能在考虑多个夹杂物相互响应的情况下计算材料应力、应变场，并实现了计算结果的三维显示．计算结果与文献中的计算结果非常吻合．本文编制的数值计算程序不仅可以用于研究复合材料的损伤演化及失效，而且利用特殊构型的椭球空洞来模拟裂纹，可以计算裂纹群的应力、应变场。     

产品易碎性的评定—理论和试验方法

本文以冲击谱为基础探讨了评定产品易损性的理论及其试验方法,给出了产品损坏边界曲线的形成理论,从而为进行产品的运输缓冲包装设计提供了基础。