考虑液-固耦合的大型超高压换流变压器地震响应研究

针对大型超高压换流变压器的地震响应问题,以一超高压±800kV换流变压器为研究对象,考虑其本体中油与箱壁的相互作用建立三维有限元分析模型,采用LS-DYNA分析换流变压器的自振特性、地震作用下的动力响应规律以及换流变压器的薄弱部位。研究结果显示,对于大型超高压换流变压器,本体中油与箱壁的相互作用对结构动力响应有一定的放大作用,进行自振特性和地震响应分析时应考虑;套管体系的薄弱部位为套管的底部和中间部位,在这两个位置拉应力和压应力最大值交替出现;换流变套管体系在地震作用下的位移较大,套管顶部的导线应设置足够大的伸缩距离。     

SCREENING FOR ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES IN SOME MARINE ALGAE FROM THE FUJIAN COAST OF CHINA WITH THREE DIFFERENT SOLVENTS

Three different solvents viz ethanol, acetone and methanol-toluene (3:1) were used to extract antibiotics from 23 species of marine algae belonging to the Chlomphyta, Phaeophyta and Rhodophyta. Their crude extracts were tested for antibacterial and antifungal activities. Among them, the ethanol extract showed the strongest activity against the bacteria and fungi tested. Four species of the Rhodophyta (Laurenc/a okamurai, Dasya scoparia, Grateloupia filicina and plocamium telfairiae ) showed a wide spectrum of antibacterial activity. Every solvent extract from the four species was active against all the bacteria tested. The test bacterium Pseudomonas solancearum and the fungus Penicilium citrinum were most sensitive to the extracts of marine algae. In general, the extracts of seaweeds inhibited bacteria more strongly than fungi and species of the Rhodophyta showed the greatest activity against the bacteria and fungi tested.     

大型换流站阀厅结构地震响应弹塑性分析

利用有限元方法对带悬挂阀的阀厅结构进行地震响应弹塑性分析,研究不同场地土条件、不同地震动作用对阀厅结构以及悬吊设备地震响应的影响.研究结果表明:阀厅结构在纵向和三向地震作用下存在较明显的扭转效应;三向地震输入时,吊杆产生的拉力约为单向输入的2倍;悬吊设备竖向地震响应大于水平地震响应,大震下悬吊设备竖向加速度约为水平向的...     

COVID-19风险冲击对疫区农户生计资本的影响及其抵御效应——以湖北、安徽、重庆为例

新冠肺炎(COVID-19)疫情给农户生计发展带来了重大风险,而生计资本是抵御疫情冲击、阻断返贫危机的关键。论文以重点疫区湖北省及周边地区为研究区域,基于可持续生计分析框架,从生计资本“结构—存量”多维视角出发,采用内生转换回归模型分析疫区465户农户生计资本对疫情风险的抵御作用。研究发现：① 重点疫区农户生计资本总量不高,疫情可能诱发生计脆弱性但不是唯一要素,基层公共卫生建设也极为重要;② 生计资本对疫情风险有显著抵御效应,人力资本维度作用更为凸显,物质资本占比过高反而会削弱疫情应对能力;③ 农户生计资本结构与存量分布不均,家庭劳动力、健康投入、财富积累、居住环境、社会阅历等是核心要素;④ 疫后生计恢复主要依赖于人力与金融资本的积累,而帮扶关键在于应急和兜底保障,要根据区域农户生计特征拟定差异化的疫情常态防控举措。