黑龙江省黑山大理岩饰面石材矿床地质特征及综合利用

本文阐述了黑龙江省巴彦县黑山大理岩饰面石材矿床的地质特征、矿石的花色品种、产品的装饰性能等特点。     

东安浅成低温热液型金矿床矿物学特征

东安金矿床是与中生代火山-潜火山岩有关的浅成低温热液型金矿床.矿床具有典型的低温热液矿物组合,包括银金矿、自然银、辉银矿、黄铁矿、毒砂、黄铜矿等,蚀变作用主要为次生石英岩化、冰长石化、硅化、绢云母化、绿泥石化、泥化、玉髓化、萤石化等.矿物包裹体表明:主成矿期温度为300～200℃,成矿初始深度为0.2～1.0 km.     

A time reversal damage imaging method for structure health monitoring using Lamb waves

This paper investigates the Lamb wave imaging method combining time reversal for health monitoring of a metallic plate structure. The temporal focusing effect of the time reversal Lamb waves is investigated theoretically. It demonstrates that the focusing effect is related to the frequency dependency of the time reversal operation. Numerical simulations are conducted to study the time reversal behaviour of Lamb wave modes under broadband and narrowband excitations. The results show that the reconstructed time reversed wave exhibits close similarity to the reversed narrowband tone burst signal validating the theoretical model. To enhance the similarity, the cycle number of the excited signal should be increased. Experiments combining finite element model are then conducted to study the imaging method in the presence of damage like hole in the plate structure. In this work, the time reversal technique is used for the recompression of Lamb wave signals. Damage imaging results with time reversal using broadband and narrowband excitations are compared to those without time reversal. It suggests that the narrowband excitation combined time reversal can locate and determine the size of structural damage more precisely, but the cycle number of the excited signal should be chosen reasonably.     

从本位原则视角谈滥用征地权的法律规制

征地的本位原则是体现在征地法律制度中的解决社会矛盾的基本立场。国家作为凌驾于社会之上的力量,当它面临种种社会矛盾时,需要采取相应的法律制度来调和这些矛盾。     

基于时间反转理论的聚焦Lamb波结构损伤成像

从理论和实验上研究了时间反转法在频散和多模式的Lamb波结构健康检测方面的应用.当Lamb波在包含有损伤的板类结构中传播时,损伤的存在表现为一个被动波源.采用分布式传感器网络,基于传递函数的观点,通过推导由损伤这个被动波源产生的时间反转波场幅值的表达式,证实了当观察点位于损伤位置时,时间反转波场的幅值最大.为验证时间反转方法的聚焦效应,提出了一种适合于分布的激励/接收传感器网络的成像方法,该方法可以对损伤定位并近似确定损伤尺寸.结合有限元的实验结果显示了Lamb波检测信号的能量可在损伤处聚焦,表明时间反转