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Acta Geotechnica - This work presents the results from a series of plane strain compression experiments on medium-density sands. In these experiments, a new type of plane strain experimental... 相似文献
94.
Yang Wenbo Qian Zhihao Tu Jiulin Zhou Ziyang Yan Qixiang Fang Yong He Chuan 《地震工程与工程振动(英文版)》2022,(2):517-528
Increased attention has been given to ground-borne vibrations induced by railway vehicles and to the effects of these vibrations as they propagate through the g... 相似文献
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Yu Nan Sun Song Wang Shiwei Liu Qun Zhang Guangtao Zhang Fang Sun Xiaoxia 《中国海洋湖沼学报》2020,38(6):1799-1810
Journal of Oceanology and Limnology - Seabed photographing has been applied with various underwater camera apparatuses (UCAs) for observations of megabenthic epifauna, which reveals more details... 相似文献
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本文主要对PCM编码式的布设模式进行分析和改进,介绍PCM编码式和闭锁深度倍数式2种站点布设模式,然后在最小有效距离(MED)为6.31倍断层闭锁深度的情况下,通过精度评价方法对比2种布设模式的结果,发现二者相差不大。进一步研究MED的合理选择,结果表明,MED取20倍的闭锁深度比6.31倍的闭锁深度更为合理。在MED为20倍的情况下对比研究PCM编码式和常规闭锁深度倍数式布设模式的优劣,结果表明,PCM编码式的布设模式优于常规模式。将PCM编码式的布设模式应用于川滇地区的巧家-东川剖面进行检验,发现PCM编码式的结果优于目前站点分布得到的结果,说明合理的站点布设可得到精度更优的结果。本文研究对于断层形变监测中精确获取形变参数具有重要意义。 相似文献
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Pang Yue Fan Dejiang Sun Xiaoxia Sun Xueshi Liu Ming Yang Zuosheng 《中国海洋大学学报(英文版)》2020,19(4):801-810
For a long time, most studies about pyrite have focused on sediments while only a few have focused on pyrite in water. In this study, a method that combines the scanning electron microscopy(SEM) and the energy dispersive X-ray spectrometry(EDS) was used to compare pyrite particles suspended in water to those in associated bottom sediments, both obtained from the mixing zone of the Yangtze Estuary. It was found that the pyrite particles in the two media have similar morphologies and size distributions. The particle morphology mainly includes two types, single crystal and aggregate, and the particle size mainly ranges from 0.5 to 2 μm. The pyrite particles in water exhibit an increase in relative content towards the sea, and their transport and deposit processes are mainly affected by hydrodynamic conditions. It is concluded that the pyrite particles in the suspended matter mainly derived from the resuspension of sediments, which are products of the early diagenesis. Precursor minerals may appear during the formation of pyrite, but are generally restricted by the diagenetic environment and local microenvironment. 相似文献
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基于ERA5月平均再分析资料,利用Lorenz环流分解方法从定常和瞬变以及基流和涡旋的角度对比了北极与青藏高原臭氧低值区的动力输送特征。结果表明:动力总输送在两地上平流层作用最强,均使其臭氧浓度降低,且定常输送均强于瞬变输送,纬向与经向输送的作用均大致相反。然而,动力输送在北极地区的作用强度远大于青藏高原地区。北极地区纬向输送使得平流层中上层臭氧浓度降低,平流层下层臭氧浓度升高,经向输送的作用与之相反且强度明显偏弱,二者均主要作用于上平流层。青藏高原地区纬向和经向输送除在上平流层均使得臭氧浓度降低外,二者作用大致相反且强度相当,输送大值区在垂直方向上存在双中心结构,分别位于上平流层与上对流层—下平流层(Upper Troposphere–Lower Stratosphere,简称UTLS)区。两地区纬向和经向输送的差异均主要由定常涡旋输送所造成。青藏高原地区定常与瞬变输送的强度差异没有北极地区大。此外,两地定常和瞬变输送中涡旋对臭氧纬向平均的输送均起到主要作用,体现出涡旋输送在两地臭氧浓度变化的动力输送过程中发挥着至关重要的作用。 相似文献
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A physical model of the transition region, including upflow of the plasma in magnetic field funnels that are open to the overlying corona, is presented. A numerical study of the effects of Alfvén waves on the heating and acceleration of the nascent solar wind originating in the chromospheric network is carried out within the framework of a two-fluid model for the plasma. It is shown that waves with reasonable amplitudes can, through their pressure gradient together with the thermal pressure gradient, cause a substantial initial acceleration of the wind (on scales of a few Mm) to locally supersonic flows in the rapidly expanding magnetic field trunks of the transition region network. The concurrent proton heating is due to the energy supplied by cyclotron damping of the high-frequency Alfvén waves, which are assumed to be created through small-scale magnetic activity. The wave energy flux of the model is given as a condition at the upper chromosphere boundary, located above the thin layer where the first ionization of hydrogen takes place.Among the new numerical results are the following: Alfvén waves with an assumed f
-1 power spectrum in the frequency range from 1 to 4 Hz, and with an integrated mean amplitude ranging between 25 and 75 km s4, can produce very fast acceleration and also heating through wave dissipation. This can heat the lower corona to a temperature of 5× 105 K at a height of h=12,000 km, starting from 5× 104 K at h=3000 km. The resulting thermal and wave pressure gradients can accelerate the wind to speeds of up to 150 km s-1 at h=12,000 km, starting from 20 km s-1 at h=3000 km in a rapidly diverging flux tube. Thus the nascent solar wind becomes supersonic at heights well below the classical Parker-Type sonic point. This is a consequence of the fact that any large wave-energy flux, if it is to be conducted through the expanding funnel to the corona, implies the building-up of an associated wave-pressure gradient. Because of the diverging field geometry, this might lead to a strong initial acceleration of the flow. There is a multiplicity of solutions, depending mainly on the coronal pressure. Here we discuss two new (as compared with a static transition region model) possibilities, namely that either the flow remains supersonic or slows down abruptly by shock formation, which then yields substantial coronal heating up to the canonical 106 K for the proton temperature. 相似文献