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601.
拖曳线列阵声纳中隔振模块研究 总被引:6,自引:0,他引:6
介绍了作为隔振模块研究依据的拖缆抖动特性的试验研究结果及隔振模块理论分析方法 ,给出了隔振模块有关参数变化对隔振量影响的理论值 ,提供了隔振模块隔振量试验方法 ,某隔振模块隔振量的测量结果以及装与不装隔振模块情况下 ,声阵的拖曳噪声声压谱级的测量结果 相似文献
602.
Large-scale experiments on non-channelized turbidity currents show that a wide flow opening angle forms and a rapid dilution of the current with distance takes place. The thickness of the deposit decreases radially away from the source, resulting in tongue-shaped isopachs. The mean grain diameter also decreases with distance while the sorting improves. With increasing distance, the following succession of bedforms was observed: (Non-deposition) → parallel lamination → ripples → parallel lamination. This corresponds to the B, C and D division of the Bouma sequence for turbidites. The experiments are in good agreement with the models presented by Bouma, Mutti and Ricci Lucchi, and Walker for classical turbidites in the depositional lobes of submarine fans. 相似文献
603.
C3植物碳同位素在旱季和雨季中的变化 总被引:23,自引:1,他引:23
通过对C3植物在旱季和雨季的碳同位素测定,在尽可能将其它因素影响分离开的自然环境下,主要研究了降水因素对植物碳同位素组成的影响。结果显示,C3植物在旱季的δ^13C组成较雨季明显偏重,同时发现,不同植物种的δ^13C组成在旱季与雨季中的变化程度不一样,说明不同植物种对水分变化的响应程度有差别。 相似文献
604.
SONG Ci'an LEI Liangqi YANG Qijun 《中国地球化学学报》2007,26(3):329-332
In the Lingchuan-Daoping and Xinglu Pb-Zn ore fields in northern and eastern Guangxi Autonomous Region, Pb, Cu botanogeochemical anomalies may be ascribed to the excessive amounts of Pb and Cu taken up by the root system of plants, such as China fir (Cunninghamia lanceolata Lamb. Hook), mason pine (Pinus massoniana Lamb.) and bracken fern (Pteridium aquilinum var. latiusculum). Under transmission electron microscope (TEM), the excess Pb, Cu in the leaf cells of the plants are present as high electron-density substances, which were precipitated in the leaf cells, causing phytotoxic effects by deforming and injuring cellular tissues. The sorts of toxic elements accumulating in the leaf cells are consistent with those of the botanogeochemically anomalous elements in the polluted soil where the plants grow. In addition, the plants may also be capable of resisting the invasion of excess Cu (and Pb) . 相似文献
605.
Weak Zone Related Seismic Cycles in Progressive Failure Leading to Collapse in Brittle Crust 总被引:2,自引:0,他引:2
Until quite recently our understanding of the basic mechanical process responsible for earthquakes and faulting was not well known. It can be argued that this was partly a consequence of the complex nature of fracture in crust and in part because evidence of brittle phenomena in the natural laboratory of the earth is often obliterated or obscured by other geological processes. While it is well understood that the spatial and temporal complexity of earthquakes and the fault structures emerge from geometrical and material built-in heterogeneities, one important open question is how the shearing becomes localized into a band of intense fractures. Here we address these questions through a numerical approach of a tectonic plate by considering rockmass heterogeneity both in microscopic scale and in mesoscopic scale. Numerical simulations of the progressive failure leading to collapse under long-range slow driving forces in the far-field show earthquake-like rupture behavior. En Echelon crack-arrays are reproduced in the numerical simulation. It is demonstrated that the underlying fracturing induced acoustic emissions (or seismic events) display self-organized criticality—from disorder to order. The seismic cycles and the geometric structures of the fracture faces, which are found greatly depending on the material heterogeneity (especially on the macroscopic scale), agree with that observed experimentally in real brittle materials. It is concluded that in order to predict a main shock, one must have extremely detailed knowledge on very minor features of the earth's crust far from the place where the earthquake originated. If correct, the model proposed here seemingly provides an explanation as to why earthquakes to date are not predicted so successfully. The reason is not that we do not understand earthquake mechanisms very well but that we still know little about our earth's crust. 相似文献
606.
内蒙古海拉尔盆地大磨拐河组孢粉组合 总被引:13,自引:1,他引:13
海拉尔盆地大磨拐河组自下而上可以划分出两个孢粉组合 :哈氏三角孢 -微细云杉粉 ( Deltoidospora hallii-Piceaepollenites exilioides)组合和澳洲无突肋纹孢 -卵形光面单缝孢 ( Cicatricosisporites australiensis- L aevigato-sporites ovatus)组合 ,分别分布于大磨拐河组一段和二段 ,组合特征明显 ,可以作为研究区内地层划分对比的生物地层学依据之一。两个孢粉组合中见有属种繁多的海金沙科孢子及其他繁盛于早白垩世的孢子花粉 ,结合在数以千计的岩心样品中没有发现可靠的早期被子植物花粉的情况分析 ,推测产这两个孢粉组合的大磨拐河组的地质时代为早白垩世凡兰吟期—欧特里沃期 ( Valanginian— Hauterivian) ,不排除部分进入巴列姆期 ( Barrem ian)的可能 相似文献
607.
利用锆石形态、成分组成及年龄分析进行沉积物源区示踪的综合研究 总被引:26,自引:4,他引:26
通过盆地碎屑沉积物分析示踪源区,进而探讨区域构造演化已成为当前地学研究的热点。盆地沉积物中的锆石不但分布广泛,而且稳定性极强,因而能保存大量的源区信息。随着锆石裂变径迹及U-Pb年龄谱分析等新测试技术的发展,锆石的形态、成分组成及年龄分析已成为盆地沉积物源区示踪的重要探针。本文结合实例,介绍了目前在综合利用锆石的形态、成分组成及年代学特征进行物源示踪的一些主要进展。由于物源示踪的复杂性,在利用锆石进行物源示踪时,应充分了解区域地质背景,密切结合其它物源示踪方法。 相似文献
608.
609.
610.
The purpose of this study is to investigate the statistical relationship between hardness value and physicomechanical properties of constructional and cover rocks. The definition, measurement of hardness and classification of the rocks used are very important in construction sector. From this point of view, rock hardness is one of the most important parameters for the determination of rock properties. In this study, the determination of hardness and the physicomechanical properties of constructional and cover rocks in Çukurova region was accomplished using various methods in the laboratory. Statistical relations between physicomechanical properties and hardness of rocks were also determined. High correlations were found between the hardness methods (Shore Scleroscope, Schmidt hammer hardness), which are cheap and easy to use, and other physical and mechanical properties. It was found that physicomechanical properties can be estimated using hardness methods and compared with the calculated value from different empirical equations. 相似文献