Deep structure at northern margin of Tarim Basin

In this paper, a 2D velocity structure of the crust and the upper mantle of the northern margin of the Tarim Basin （TB） has been obtained by ray tracing and theoretical seismogram calculation under the condition of 2D lateral inhomogeneous medium using the data of seismic wide angle reflection/refraction profile from Baicheng to Da Qaidam crossing the Kuqa Depression （KD） and Tabei Uplift （TU）. And along the Baicheng to Da Qaidam profile, 4 of the 10 shot points are located in the northern margin of the TB. The results show that the character of the crust is uniform on the whole between the KD and TU, but the depth of the layers, thickness of the crust and the velocity obviously vary along the profile. Thereinto, the variation of the crust thickness mainly occurs in the middle and lower crust. The Moho has an uplifting trend near the Baicheng shot point in KD and Luntai shot point in TU, and the thickness of the crust reduces to 42 km and 47 km in these two areas, respectively. The transition zone between the KD and TU has a thickest crust, up to 52 km. In this transition zone, there are high velocity anoma- lies in the upper crust, and low velocity anomalies in the lower crust, these velocity anomalies zone is near vertical, and the sediment above them is thicker than the other areas. According to the velocity distributions, the profile can be divided into three sections： KD, TU and transition zone between them. Each section has a special velocity structural feature, the form of the crystalline basement and the relationship between the deep structure and the shallow one. The differences of velocity and tectonic between eastern and western profile in the northern margin of the Tarim Basin （NMTB） may suggest different speed and intensity of the subduction from the Tarim basin to the Tianshan orogenic belt （TOB）.     

旋转内接微梁的动力学建模及稳定性分析

在微尺度领域,材料力学性能存在尺度效应,使微梁动力学性态较传统宏观尺度柔性梁的动力学性态呈现明显不同.对固结于旋转刚环上内接微梁刚柔耦合动力学特性进行了研究,在精确描述微梁非线性变基础上,利用偶应力理论和Hamilton变分原理,在计入微梁由于横向变而引起的轴向变二耦合量条件下,推导出一次近似耦合模.首先忽略微梁纵向变影响,给出一次近似简化模,引入无量纲变量,对简化模做无量纲化处理,分析在非惯性系下内接微梁动力学响应,并与外接微梁进行比较;其次研究尺度效应对内接微梁动力特性影响.研究发现,与外接微梁只存在动力刚化效应不同,内接微梁还存在着动力柔化效应;本文给出了内接微梁无条件稳定临界径长比以及有条件稳定临界转速计算方法;尺度效应使微梁振动频率增大,振幅减小,提高了内接微梁失稳临界转速;随着模态断数增加,内接微梁失稳临界转速减小且有收敛值.     

North China sub-craton lithospheric structure elucidated through coal mine blasting

We present a super-range seismic observation along the >1300-km-long profile passing through the Yinchuan basin and the Ordos block from the blasting point towards the southeast triggered by a large-(dynamite) scale coal blast in the Ningxia Hui Autonomous Region’s Helan Mountain (yielded a profile). The seismic wave information from the uppermost mantle reflecting different depths was obtained by the China continental seismic survey. Pn refracted waves from the uppermost mantle were effectively traced up t...     

冲击波作用下多孔材料内的温度斑图动力学

强冲击作用过程中多孔材料内物理特征量(温度、密度、粒子速度、各种应力等)的分布极其复杂. 使用颗粒接触物质点方法对这类过程进行模拟, 对材料内复杂的温度场进行形态学分析, 引入“结构相似”和“过程相似”的概念, 对不同温度阈值条件下的特征结构极其演化过程进行比较研究. 发现: 在同一材料中, 如果冲击强度和温度阈值选取合适, 那么高温区域及其演化过程会表现出极其相似的特征. 当孔隙度较高时, 过程相似要求的温度阈值和冲击速度成二次抛物线关系; 随着孔隙度降低, 温度阈值随冲击速度升高的速率有所加快. 在不同材料中, 在冲击强度一定的情况下, 过程相似要求的温度阈值和孔隙度在一定范围内表现出幂律行为. 其他类型的特征结构可以按同样方式进行研究分析.