漫谈粒子和宇宙二十一 现代宇宙学简说（续）

宇宙微波背景辐射 宇宙微波背景辐射是一种充满整个宇宙的电磁辐射。其特征和绝对温标2．7开的黑体辐射相同,频率属于微波范围。宇宙微波背景辐射大约产生于大爆炸后的三十万年。     

A modified Kelvin impact model for pounding simulation of base-isolated building with adjacent structures

Base isolation can effectively reduce the seismic forces on a superstructure,particularly in low-to medium-rise buildings.However,under strong near-fault ground motions,pounding may occur at the isolation level between the baseisolated building(BIB)and its surrounding retaining walls.To effectively investigate the behavior of the BIB pounding with adjacent structures,after assessing some commonly used impact models,a modified Kelvin impact model is proposed in this paper.Relevant parameters in the modifi...