简介:HeavilypopulatedbyBeijingandTianjincities,BohaibasinisaseismicallyactiveCenozoicbasinsufferingfromhugelostbydevastatingearthquakes,suchasTangshanearthquake.Theattenuation(QPandQS)ofthesurficialQuaternarysedimenthasnotbeenstudiedatnaturalseismicfrequency(1-10Hz),whichiscrucialtoearthquakehazardsstudy.Boreholeseismicrecordsofmicroearthquakeprovideusagoodwaytostudythevelocityandattenuationofthesurficialstructure(0-500m).Wefoundthattherearetwopulseswellseparatedwithsimplewaveformsonboreholeseismicrecordsfromthe2006MW4.9Wen'anearthquakesequence.Thenweperformedwaveformmodelingwithgeneralizedraytheory(GRT)toconfirmthatthetwopulsesaredirectwaveandsurfacereflectedwave,andfoundthattheaveragevPandvSofthetop300minthisregionareabout1.8km/sand0.42km/s,leadingtohighvP/vSratioof4.3.Wealsomodeledsurfacere-flectedwavewithpropagatingmatrixmethodtoconstrainQSandthenearsurfacevelocitystructure.OurmodelingindicatesthatQSisatleast30,orprobablyupto100,muchlargerthanthetypicallyassumedextremelylowQ(~10),butconsistentwithQSmodelinginMississippiembayment.Also,thevelocitygradientjustbeneaththefreesurface(0-50m)isverylargeandvelocityincreasesgraduallyatlargerdepth.Ourmodelingdemonstratestheimportanceofboreholeseismicrecordsinresolvingshallowvelocityandattenuationstructure,andhencemayhelpinearthquakehazardsimulation.
简介:QS世界大学排行榜在一定程度上反映了各国大学的办学现状。本文分析了2013-2015年QS世界大学排行榜的基础数据,发现亚洲大学进入世界前700强的数量有逐年增加的趋势,但进入世界前100强的比例仍比较低。通过各项具体指标观测,亚洲大学整体国际化水平不高、论文被引率较低。数据显示,亚洲大学在材料科学、计算机科学、化学工程、数学、化学、土木与结构工程等学科展现了较强的实力,在哲学、英语语言与文学、地理学、历史学、社会学、教育学、法学学科领域仍较为薄弱。因此,亚洲大学应根据各国的实际情况,结合自身的定位进行不断调整,一方面迅速提高国际化水平,一方面加快实现从量变到质变的转换。