Seismic detectability of anomalous structure at the top of the Earth’s outer core with broadband array analysis of SmKS phases     

Satoru Tanaka 《Physics of the Earth and Planetary Interiors》2004,141(3):141-152

I have examined precisely the differential travel times and waveforms of SmKS seismic phases propagating under the southern Indian Ocean obtained from African broadband seismic arrays. The SmKS phases analyzed in this study travel in the mantle with weak heterogeneity confirmed by a global tomographic study for the distance range of 115-135°. The SmKS differential times were obtained from a vespagram (a stack intensity on a time-slowness diagram), and comparison with the vespagram created from synthetic waveforms with PREM gives the travel-time residual for each event-array pair. Although the residuals of S3KS-S2KS times exhibit apparently a systematic dependence on epicentral distance, this is likely due to small-scale heterogeneity beneath the Oceania where is covered by the SmKS ray entering points at the CMB. Waveform modeling was applied to a record section with a small travel-time residual that suggests a small effect from the mantle heterogeneity on the data set, I found that a low-velocity zone in the outermost 50 km in the core rather than PREM can explain an additional arrival detected just after the S3KS phase. This result is still inconclusive because of the small number of data and non-uniqueness of the model and ambiguity due to mantle structure. However, accumulation of the precise measurement described in this study may help the reduction of uncertainty and trade-offs.  相似文献   

地震测深数据文件及其处理系统     

王椿镛  陆原 《地球物理学报》1991,34(4):455-464

本文在我国大规模开展地震测深工作的基础上,提出了地震测深数据文件系统,其目的在于在测深资料解释中引进数字处理技术,增加地震记录可用的信息量,建立地震测深数据库,从而促进我国深部研究工作中资料的相互交流. 在IBM-PC/XT微型计算机上,与本文的数据文件系统相应的数据采集、文件组织、绘制地震记录截面图以及对数字记录进行预处理等方面软件设计已经完成,从而建立了较完善的地震测深数据处理软件包.这个软件包在野外的使用表明,它具有效率高、使用方便的优点.  相似文献   

Assessing the suitability of data from Sentinel-1A and 2A for crop classification     

Rei Sonobe  Yuki Yamaya  Hiroshi Tani  Xiufeng Wang  Nobuyuki Kobayashi  Kan-ichiro Mochizuki 《地理信息系统科学与遥感》2017,54(6):918-938

Sentinel-1A C-SAR and Sentinel-2A MultiSpectral Instrument (MSI) provide data applicable to the remote identification of crop type. In this study, six crop types (beans, beetroot, grass, maize, potato, and winter wheat) were identified using five C-SAR images and one MSI image acquired during the 2016 growing season. To assess the potential for accurate crop classification with existing supervised learning models, the four different approaches namely kernel-based extreme learning machine (KELM), multilayer feedforward neural networks, random forests, and support vector machine were compared. Algorithm hyperparameters were tuned using Bayesian optimization. Overall, KELM yielded the highest performance, achieving an overall classification accuracy of 96.8%. Evaluation of the sensitivity of classification models and relative importance of data types using data-based sensitivity analysis showed that the set of VV polarization data acquired on 24 July (Sentinel-1A) and band 4 data (Sentinel-2A) had the greatest potential for use in crop classification.  相似文献   

Excursion to Farnham: 19th June, 1926     

H.G. Dines 《Proceedings of the Geologists' Association. Geologists' Association》1927,38(3):402-403

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Excursion to east Yorkshire: Monday,July 19th, 1875, and five following days     

《Proceedings of the Geologists' Association. Geologists' Association》1875,4(5):326-336

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胶州湾3种哲水蚤种群动态的研究   总被引：1，自引：1，他引：1  

仲学锋  肖贻昌 《海洋科学》1992,16(1):44-48

本文研究了胶州湾内小拟哲水蚤(Paracalanus parvus Claus),双刺纺锤水蚤(Acartia bifilosa Giesbrecht)和太平洋纺锤水蚤(A.pacifica Steuer)3种哲水蚤一年内的种群结构和种群数量的季节变化规律,并讨论了体长的季节变化及其与温度之间的关系。  相似文献   

Fatigue Crack Propagation in Steel A131 Under Ice Loading of Crushing,Bending and Buckling     

段梦兰  樊晓东  宋立崧  方华灿  James C. M. LI 《中国海洋工程》2001,(3):315-328

Three types of ice loading, which are most commonly present when ice acts on structures, are chosen and simulated for use of fatigue crack propagation tests on offshore structural steel A131. The three types of ice categorized in accordance with the failure modes when acting on structures called crushing ice, bending ice, and buckling ice, respectively. This paper presents an experimental investigation on the fatigue crack propagation behavior of widely used high strength steel A131 for offshore jackets in the loading environment of ice crushing, bending, and buckling. The test results of fatigue crack propagation in steel A131 under these simulated ice loading at temperature 292K. are presented and analyzed in detail in this paper. The amplitude root mean square stress intensity factor is optimized to be the fundamental parameter of fatigue crack propagation for all types of ice loading histories. The results are also compared with constant amplitude fatigue crack propagation conclusions as in wave loa  相似文献   

十二烷基硫酸钠对卤虫生长和发育的影响     

郑琰晶  陈燕平  吴进孝  陈琳 《海洋通报》2007,26(3):117-120

以卤虫初孵幼体为试验材料,研究了十二烷基硫酸钠(SDS)对其生长和发育的影响。96h试验期间内测得的结果显示,SDS在24h,48h,72h及96h对卤虫生长的无可见影响浓度(NOEC)分别为11.4,8.7,<8.7,<8.7mg/L;对卤虫发育的无可见影响浓度分别为19.2,19.2,<8.7,<8.7mg/L;SDS可以抑制卤虫胸部分节及胸肢的分化,但不影响复眼的形成。试验结果表明,卤虫生长指标较发育指标敏感,可以将其作为毒性检验的观测指标。  相似文献   

Cloning of cytochrome P450 1A (CYP1A) genes from the hermaphrodite fish Rivulus marmoratus and the Japanese medaka Oryzias latipes     

Il-Chan Kim  Young Ja Kim  Yong-Dal Yoon  Shoji Kawamura  Yong-Sung Lee  Jae-Seong Lee   《Marine environmental research》2004,58(2-5):125

To use two small fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae) and the Japanese medaka Oryzias latipes (Belloniformes) as testing models in molecular ecotoxicology, we have cloned the cytochrome P450 1A (CYP1A) gene after screening of both genomic DNA libraries, and sequenced 11,863 and 7,243 bp including all the exons and introns with promoter regions, respectively. The Rivulus and the medaka CYP1A gene consisted of seven exons (including non-coding exons) with high homology to mammals. In the promoter region, Rivulus CYP1A gene has seven xenobiotic response elements (XREs) and two metal response elements (MREs), while the Japanese medaka CYP1A gene has six XREs and four MREs. Interestingly, medaka CYP1A gene has a number of MREs at the promoter, which may affect its response on metal exposure. We describe here the gene structure of both fish CYP1A genes.  相似文献   

辽东湾沿岸海水及贝类中甲肝病毒分布的研究          下载免费PDF全文

樊景凤  宋立超  张喜昌  梁玉波  关道明 《海洋科学》2007,31(2):52-54

用RT-PCR方法检测辽东湾几个重点沿岸海域表层海水和几种经济贝类样品中甲肝病毒的分布。结果表明,6个重点沿岸海域表层海水中均检出甲肝病毒(Hepatitis A virus,HAV),6种经济贝类样品中有4个样品检出甲肝病毒。检测结果显示,辽东湾某些重点沿岸海域受陆源生活污水影响严重,有关部门应加强海洋环境和海产贝类卫生安全监测和管理,以避免引发甲型肝炎暴发流行。  相似文献