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251.
By us considered as Albo-Aptian in age and generated through halokinetic processes, the Bosmendiette breccias have been recently interpreted as Selandian (Palaeocene) globigerine-bearing sediments deposited in sub-marine canyons within a deep trough crossing the Pyrenees, from the Mediterranean Sea to the Atlantic Ocean. These breccias are really azoic in their lower part and contain a scarce microfauna including radolarians and benthic foraminifera at the top of the formation. They are unconformably covered by the Urgo-Aptian limestones and marls and indicate, under opening marine conditions, Lower Cretaceous collapse movements and northward sliding of the Jurassic slumped cover, related to the growth of the Béloscare–Apoura diapir. To cite this article: J. Canérot et al., C. R. Geoscience 336 (2004).  相似文献   
252.
大陆科学钻探施工用钻探技术和施工战略   总被引:1,自引:0,他引:1       下载免费PDF全文
张伟 《探矿工程》2002,(3):58-61
国外实施大陆科学钻探采用的钻探技术有地质岩心钻探技术,石油钻探技术,组合式钻探技术,以及前苏联和俄罗斯的具有鲜明特色的科学深钻技术,分别介绍了它们各自的技术特点及优缺点,并介绍了科学深孔和超深孔的2种施工战略,即超前孔裸眼钻进方法和双孔方案。  相似文献   
253.
The objective of this study is to investigate the effect of boundary element details of structural walls on their deformation capacities. Structural walls considered in this study have different sectional shapes and/or transverse reinforcement content at the boundaries of the walls (called boundary element details hereafter). Four full‐scale wall specimens (3000mm (hw)×1500mm (lw)×200mm (T)) were fabricated and tested. Three specimens are rectangular in section and the other specimen has a barbell‐shaped cross‐section (a wall with boundary columns). The rectangular wall specimens are reinforced according to the common practice used for reinforced concrete residence buildings in Korea and Chile. In this study, the primary variable for these rectangular specimens is the content of transverse reinforcement to confine the boundary elements of a wall. The barbell‐shaped specimen was designed in compliance with ACI 318‐95. The response of the barbell‐shaped specimen is compared with those of other rectangular specimens. The effective aspect ratio of the specimens is set to two in this study. Based on the experimental results, it is found that the deformation capacities of walls, which are represented by displacement ductility, drift ratio and energy dissipation capacities, are affected by the boundary element details. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
254.
Yu Ye  Dong Li 《Urban geography》2018,39(4):631-652
Recent urban transformations in China have led to critical reflections on the low-quality urban expansion in the previous decades and called for the making of vital and lively urban places. To date, limited research has been devoted to empirically testing the relationship between urban design, urban morphology, and urban vitality in Chinese cities. This paper employs new urban data and analytical methods and explores the relationship between urban morphology and urban vitality using regression models. Shenzhen, one of the largest and fastest growing cities in China, is selected as the case study. The regression analysis focuses on two morphological factors, density and typology, while controlling for the accessibility, functional mix, and size of individual blocks. The presence of small catering businesses is used as a proxy for urban vitality. The analysis suggests that both typology and density matter for urban vitality, with typology playing a more important role. More specifically, “block” and “strip” types tend to show significant positive effects on urban vitality. The implications for urban planning and design practices are discussed.  相似文献   
255.
A new approach to the study of the large-scale stellar cluster distribution in the Galaxy based on two-point correlation techniques is presented. The basic formalism for this method is outlined, and its applications are then investigated by the use of a simple model of cluster distribution in the Galaxy. This provides an estimate of the potentials of the two-point correlation function for indicating clustering in the measured star positions, which can be related to the presence of star clusters in the observed field. This technique is then applied to several areas of the Two Micron Galactic Survey catalogue, from which information is obtained on the distribution of clusters according to position in the Galaxy, as well as about age, density of stars, etc.  相似文献   
256.
Results from photographic and CCD photometric observations of the pre-main sequence star V 350 Cep are presented. A continued gradual rise of brightness resembling the light curves of the FUOR type stars is observed. A search in the WFPDB was made to find old photographic observations of V 350 Cep.  相似文献   
257.
We found 36 emission lines in the spectrum of the planetary nebula NGC 2438, and we determined its exc. class to be about 6–7. The nebular RVhel = 60.3 ± 3.6 km/s (5 spectra) is in agreement with RVhel = 60.8 ± 4.0 km/s of 4 cluster stars (10 spectra). We conclude that contrary to earlier statements the nebula is probably associated with the cluster.  相似文献   
258.
准确刻画精细化尺度下的城市房租空间格局,对于研究城市居住行为、提高城市规划合理性十分重要。文章提出了一种基于互联网房租数据作为可靠数据源的城市房租空间格局制图方法。以深圳市作为研究区,通过广泛采集开放平台中用户发布的租房信息,绘制社区行政区尺度的房租空间分布图。房租空间制图涉及到对于没有样本数据区域平均房租的评估,因此,选取一系列与房租相关的房产属性、房屋区位及配套设施的评价指标,采用前馈神经网络技术构建评估模型。以2015年深圳市的住宅租赁市场作为研究对象,通过对结果的分析,以及与权威部门发布的统计数据进行比较,表明此方法能够有效地绘制社区尺度下城市房租的空间分布,模型预测结果的误差(%RMSE)为13.87%。所使用的互联网房租数据、POIs数据及前馈神经网络的建模工具均是开源的,而且所提出的方法论具有普适性,能够应用于其他研究区的房租空间格局制图,具有实践意义。  相似文献   
259.
由于前后桨的相互干扰,对转桨的推力和扭矩呈现非常明显的非定常特点。一些主要的设计参数,如前后桨叶数比、推力比以及桨盘面间距对对转桨的水动力性能皆有一定的影响。分别对它们进行系统的研究有助于减弱对转桨的不利干扰,最大程度地回收周向动能。本文采用CFD方法首先分析了叶数比的影响,推力和扭矩的预报结果与试验值吻合良好,结果显示,叶数比为4∶5的对转桨拥有较好的稳定性。另外,对转桨的效率比等效单桨高8.73%~10.2%左右。最后研究了前后桨不同间距和不同推力比的影响,结果显示,增加前后桨的间距可以有效减小前后桨的不利干扰,但是在一定间距内或者推力比在1附近,对转桨水动力均值变化影响不大。  相似文献   
260.
为分析网形结构对重力网平差结果的影响,利用北天山测网改造后的最新4期流动重力观测数据,分析测网中存在长支线对整网数据处理结果的影响。结果显示,长支线的存在使北天山最大异常变化达到260 μGal。将支线连成闭合环再进行平差计算,得到的最大重力变化量减小到60 μGal,表明测线上的误差积累导致支线末端测点重力值可靠性差,严重影响异常重力变化的识别。由于观测原因形成长支线时,为正确识别异常信息,采取适当的数据处理方法,将支线连接成闭合环,可以有效提高测网整体平差结果的可靠性。  相似文献   
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