Advanced microfluidic technology was used to examine the microscopic viscous and inertial effects evolution of water flow in rock joints. The influence of void space on fluid flow behaviour in rock joints under differ...Advanced microfluidic technology was used to examine the microscopic viscous and inertial effects evolution of water flow in rock joints. The influence of void space on fluid flow behaviour in rock joints under different flow velocities was experimentally investigated at the micro scale. Using advanced fabrication technology of microfluidic device, micro flow channels of semicircular, triangular, rectangular and pentagonal cavities were fabricated to simulate different void space of rock joints, respectively. Using the fluorescence labelling approach, the trajectory of water flow was captured by the microscope digital camera when it passed over the cavity under different flow velocities. The flow tests show that the flow trajectory deviated towards the inside of the cavity at low flow velocities. With the increase in flow velocity, this degree of flow trajectory deviation decreased until there was no trajectory deviation for flow in the straight parallel channel. The flow trajectory deviation initially reduced from the void corner near the entrance. At the same time, a small eddy appeared near the void corner of the entrance. The size and intensity of the eddy increased with the flow velocity until it occupied the whole cavity domain. The gradual reduction of flow trajectory near the straight parallel channel and the growth of eddy inside the cavity reflect the evolution of microscopic viscous and inertial forces under different flow velocities.The eddy formed inside the cavity does not contribute to the total flow flux, but the running of the eddy consumes flow energy. This amount of pressure loss due to voids could contribute to the nonlinear deviation of fracture fluid flow from Darcy's law. This study contributes to the fundamental understanding of non-Darcy's flow occurrence in rock joints at the micro scale.展开更多
This study aims at exploring the void space gas effect of earthquake-triggered slope instability and providing a new method for studying the formation mechanism of earthquake-triggered landslides. We analysed the basi...This study aims at exploring the void space gas effect of earthquake-triggered slope instability and providing a new method for studying the formation mechanism of earthquake-triggered landslides. We analysed the basic characteristics, kinematic characteristics, initiation mechanisms and physical mechanical parameters of the Daguangbao landslide, generalized a landslide prototype, and established a geological model and performed simulation tests. Based on the seismic wave propagation theory of rock-soil mass, rock fracture mechanics and the effective stress principle, we found that the void space gas effect is due to the occurrence of excess void space gas pressure when the dynamic response of seismic loads impacts the void space gas in weak intercalated layers of the slope. The excess void space gas pressure generated by the vibration(earthquake) damages the rock mass around the void space with a certain regularity. The model test results show that the effective shear strength of the rock mass can be reduced by 4.4% to 21.6% due to the void space gas effect.展开更多
基于机器视觉的水下垃圾清理机器人已经成为修复海洋生态的一种有效手段,但是由于复杂的水下环境会造成采集图像的分辨率较低,导致垃圾检测精度较低。针对上述问题,提出一种基于改进YOLOX-S网络的水下垃圾检测算法,该算法通过采用空间...基于机器视觉的水下垃圾清理机器人已经成为修复海洋生态的一种有效手段,但是由于复杂的水下环境会造成采集图像的分辨率较低,导致垃圾检测精度较低。针对上述问题,提出一种基于改进YOLOX-S网络的水下垃圾检测算法,该算法通过采用空间到深度卷积模块代替下采样模块提高了图像中物体有效特征的提取能力,提升了其检测精度;主干网络引入空洞空间卷积池化金字塔模块增强了深层特征提取能力,以及颈部网络引入轻量化幽灵混洗卷积模块和Vov幽灵混洗跨阶段瓶颈模块获取了更多的多尺度特征信息,进一步提升检测精度。实验结果表明,在YOLOX网络中引入空间到深度卷积模块、幽灵混洗卷积模块和Vov幽灵混洗跨阶段瓶颈模块、空洞空间卷积池化金字塔模块均可提高YOLOX模型的检测精度。改进后YOLOX-S模型的平均精度均值(mean average precision,mAP)达到了67.4%,较原YOLOX-S模型提高了3.1%,有效提升了复杂海洋环境中的垃圾检测能力。展开更多
基金support from the Australian Research Council-linkage Project
文摘Advanced microfluidic technology was used to examine the microscopic viscous and inertial effects evolution of water flow in rock joints. The influence of void space on fluid flow behaviour in rock joints under different flow velocities was experimentally investigated at the micro scale. Using advanced fabrication technology of microfluidic device, micro flow channels of semicircular, triangular, rectangular and pentagonal cavities were fabricated to simulate different void space of rock joints, respectively. Using the fluorescence labelling approach, the trajectory of water flow was captured by the microscope digital camera when it passed over the cavity under different flow velocities. The flow tests show that the flow trajectory deviated towards the inside of the cavity at low flow velocities. With the increase in flow velocity, this degree of flow trajectory deviation decreased until there was no trajectory deviation for flow in the straight parallel channel. The flow trajectory deviation initially reduced from the void corner near the entrance. At the same time, a small eddy appeared near the void corner of the entrance. The size and intensity of the eddy increased with the flow velocity until it occupied the whole cavity domain. The gradual reduction of flow trajectory near the straight parallel channel and the growth of eddy inside the cavity reflect the evolution of microscopic viscous and inertial forces under different flow velocities.The eddy formed inside the cavity does not contribute to the total flow flux, but the running of the eddy consumes flow energy. This amount of pressure loss due to voids could contribute to the nonlinear deviation of fracture fluid flow from Darcy's law. This study contributes to the fundamental understanding of non-Darcy's flow occurrence in rock joints at the micro scale.
基金funded by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (No.SKLGP2016Z015)the Natural Science Foundation of China (No. 41572308)
文摘This study aims at exploring the void space gas effect of earthquake-triggered slope instability and providing a new method for studying the formation mechanism of earthquake-triggered landslides. We analysed the basic characteristics, kinematic characteristics, initiation mechanisms and physical mechanical parameters of the Daguangbao landslide, generalized a landslide prototype, and established a geological model and performed simulation tests. Based on the seismic wave propagation theory of rock-soil mass, rock fracture mechanics and the effective stress principle, we found that the void space gas effect is due to the occurrence of excess void space gas pressure when the dynamic response of seismic loads impacts the void space gas in weak intercalated layers of the slope. The excess void space gas pressure generated by the vibration(earthquake) damages the rock mass around the void space with a certain regularity. The model test results show that the effective shear strength of the rock mass can be reduced by 4.4% to 21.6% due to the void space gas effect.
文摘基于机器视觉的水下垃圾清理机器人已经成为修复海洋生态的一种有效手段,但是由于复杂的水下环境会造成采集图像的分辨率较低,导致垃圾检测精度较低。针对上述问题,提出一种基于改进YOLOX-S网络的水下垃圾检测算法,该算法通过采用空间到深度卷积模块代替下采样模块提高了图像中物体有效特征的提取能力,提升了其检测精度;主干网络引入空洞空间卷积池化金字塔模块增强了深层特征提取能力,以及颈部网络引入轻量化幽灵混洗卷积模块和Vov幽灵混洗跨阶段瓶颈模块获取了更多的多尺度特征信息,进一步提升检测精度。实验结果表明,在YOLOX网络中引入空间到深度卷积模块、幽灵混洗卷积模块和Vov幽灵混洗跨阶段瓶颈模块、空洞空间卷积池化金字塔模块均可提高YOLOX模型的检测精度。改进后YOLOX-S模型的平均精度均值(mean average precision,mAP)达到了67.4%,较原YOLOX-S模型提高了3.1%,有效提升了复杂海洋环境中的垃圾检测能力。
