基于振型的结构平面规则性界定方法          下载免费PDF全文

刘雨桐  刘玉森  王文君  张香成   《世界地震工程》2018,34(4):104-112

为研究结构平面规则性的界定方法,首先分析了平面规则结构的振型序列特征并验证了其稳定性。以L型结构为例,通过将规则结构的振型序列特征与L型结构的振型序列特征对比,得到了不同L型结构的平面规则性界定曲线,指出了凸出部分的横向长度与横向总长度之比、凸出部分的纵向长度与纵向总长度之比和结构高度是影响L型结构平面规则与否的重要因素,并建议平面不规则结构位移比限值取1.3。提出了基于振型的结构平面规则性界定方法,即:与平面规则结构的振型序列相比,平面不规则结构的振型序列中不利振型（扭转振型、包含扭转的耦合振型及局部振型等需考虑空间效应的振型）会提前。通过对一实际结构进行计算分析,验证了基于振型的结构平面规则性界定方法的优越性和正确性。  相似文献   

ANALYSIS OF AN ISOLATED STORM EVENT HYDROGRAPH BY IDENTIFYING THE INFLOW SEQUENCE TO A NON-LINEAR CONCEPTUAL RESERVOIR     

A. N. MANDEVILLE 《水文研究》1996,10(7):995-1002

In an isolated storm event model relating gross rainfall to the flow hydrograph, the shape transformation component can be composed of a number of subsystems. It is assumed here that this component contains, along with other subsystems, a non-linear conceptual reservoir expressed in general terms. Given an isolated storm event, a procedure is described that directly identifies the particular inflow sequence that needs to be applied to this reservoir to reproduce the observed discharge hydrograph as outflow. This procedure makes use of information contained only in the observed hydrograph and does not rely on prior knowledge of the gross or net rainfall hyetographs. Nor is it necessary to identify in full the storage–outflow relation of the non-linear reservoir used. Future comparisons between the gross rainfall hyetograph and the identified inflow sequence should be facilitated by the procedure's ability to remove the long trailing recession belonging to the outflow.  相似文献   

缘管浒苔5.8SrDNA及其转录间隔区的序列测定及分析     

郑明刚  臧家业  张进兴  孙修勤 《海洋科学进展》2010,28(1)

利用PCR扩增、克隆和测序的方法对青岛市红岛虾池生长的缘管浒苔(Enteromorpha linza)的5.8S rD-NA及其转录间隔区ITS序列进行了分析,并依据ITS序列构建了浒苔属不同种之间的进化树。结果表明,获得了核糖体DNA完整的ITS和5.8S rDNA序列,ITS1为195 bp,5.8S rDNA为155 bp,ITS2为184 bp,总长度GC含量为63%。缘管浒苔与浒苔和曲浒苔的序列差异百分率较小,分别为2.4%和4.6%,与(U.olivascens)的序列差异百分率最大,为16.7%。Kimura-2参数遗传距离结果表明缘管浒苔和浒苔的遗传进化关系较近。  相似文献   

Upper Carboniferous to Lower Permian transgressive–regressive sequences of central Spitsbergen,Arctic Norway     

Tommy J. Samuelsberg  Neil A. H. Pickard 《Geological Journal》1999,34(4):393-411

Investigation of the Upper Carboniferous to Lower Permian sedimentary strata of central Spitsbergen shows that this highly cyclic rock succession is composed of four long-term transgressive–regressive cycles. These long-term cycles are themselves composed of stacked higher order cycles. Transgressive phases are characterized by increasing accommodation space, and include a basal transgressive part of marked retrogradation of facies belts and thickening-upward component cycles. Regressive phases are characterized by decreasing accommodation space, displayed by progradation of facies belts, overall shallowing and increased restriction of the depositional environment, influx of coarse terrigenous sediments and increasing evidence of exposure and/or non-deposition. The oldest transgressive–regressive sequence identified, Sequence 1, is of Serpukhovian to Bashkirian age and represents a syn-rift sequence. Also composed of syn-rift sediments is the transgressive–regressive Moscovian to mid-Gzhelian-aged Sequence 2. The late Gzhelian to late Asselian Sequence 3 is mainly a post-rift sequence. The youngest sequence, Sequence 4, is of Sakmarian to possible Artinskian age, and is also composed of post-rift sediments. The individual transgressive–regressive cycles are defined as second-order cycles, based on lithological signatures, lateral extent of bounding unconformities, and the actual time period the cycles span. Local tectonic activity is believed to control to some extent the development of short-term cycles in the syn-rift succession. However, cyclicity within the long-term cycles is mainly controlled by eustatic sea-level fluctuations, and therefore enables them to be correlated to other Circum-Arctic regions. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献