By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instr...By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.展开更多
针对现有多模态配准算法面临的复杂背景干扰、配准精度不高和配准效率低等问题,提出一种基于双通道注意力(Tw-A)网络的无人机(UAV)多模态图像配准模型,并将它应用于UAV巡检中,以提高对多模态图像的配准精度和效率。首先,提出Tw-A,以同...针对现有多模态配准算法面临的复杂背景干扰、配准精度不高和配准效率低等问题,提出一种基于双通道注意力(Tw-A)网络的无人机(UAV)多模态图像配准模型,并将它应用于UAV巡检中,以提高对多模态图像的配准精度和效率。首先,提出Tw-A,以同时提取红外和可见光图像的特征与描述子,并采用位置注意力结合通道注意力的方式增强解码后的全局特征,从而使模型能抵御复杂背景的干扰;其次,采用特征金字塔(FP)模块对图像进行多尺度特征配准,以提取不同尺度目标尤其是小目标的特征,从而增加提取的特征点数,提高配准精度,并降低误匹配率;最后,采用一种单应性自适应匹配策略HomographyNet,根据输入图像对的难度自动调整计算复杂度,以提高特征点的复检率和增强跨域的实用性,减小计算量,并提高配准效率。实验结果表明:所提模型的精度较高,均方根误差(RMSE)相较于MURF、Efficient LoFTR(Efficient Local Feature matching with TRansformers)、ALIKE(Accurate and LIghtweight Keypoint detection and descriptor Extraction)和SuperGlue分别降低了3.5%、5.3%、12.6%和2.4%。并且,所提模型在复杂背景干扰下仍能保持良好的鲁棒性,可以满足UAV巡检图像配准的需求。展开更多
Phase equilibrium in the ternary CuO-PbO-Ag system has been investigated using differential thermal analysis(DTA),thermogravimetry(TG),scanning electron microscopy(SEM) and X-ray diffraction(XRD) techniques.In the ter...Phase equilibrium in the ternary CuO-PbO-Ag system has been investigated using differential thermal analysis(DTA),thermogravimetry(TG),scanning electron microscopy(SEM) and X-ray diffraction(XRD) techniques.In the ternary CuO-PbO-Ag system,there is a eutectic reaction CuO+PbO+Ag=L at 750℃ and a composition of 12.04 mol.% Ag,16.35 mol.% CuO and 71.61 mol.% PbO.Two miscibility gaps near the two binary tie lines PbO-Ag and CuO-Ag were detected. No binary or ternary compound was detected in the ternary system.SEM and energy dispersive spectroscopy(EDS) confirm the presence of two liquid phases and the eutectic point.展开更多
基金support of the National Basic Research 973 Program of China (No.2013CB036003)the National Natural Science Foundation of China (No.51374198)the National Natural Science Foundation young investigator grant program of China (Nos.51204163,51504247,and 51404255)
文摘By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.
文摘针对现有多模态配准算法面临的复杂背景干扰、配准精度不高和配准效率低等问题,提出一种基于双通道注意力(Tw-A)网络的无人机(UAV)多模态图像配准模型,并将它应用于UAV巡检中,以提高对多模态图像的配准精度和效率。首先,提出Tw-A,以同时提取红外和可见光图像的特征与描述子,并采用位置注意力结合通道注意力的方式增强解码后的全局特征,从而使模型能抵御复杂背景的干扰;其次,采用特征金字塔(FP)模块对图像进行多尺度特征配准,以提取不同尺度目标尤其是小目标的特征,从而增加提取的特征点数,提高配准精度,并降低误匹配率;最后,采用一种单应性自适应匹配策略HomographyNet,根据输入图像对的难度自动调整计算复杂度,以提高特征点的复检率和增强跨域的实用性,减小计算量,并提高配准效率。实验结果表明:所提模型的精度较高,均方根误差(RMSE)相较于MURF、Efficient LoFTR(Efficient Local Feature matching with TRansformers)、ALIKE(Accurate and LIghtweight Keypoint detection and descriptor Extraction)和SuperGlue分别降低了3.5%、5.3%、12.6%和2.4%。并且,所提模型在复杂背景干扰下仍能保持良好的鲁棒性,可以满足UAV巡检图像配准的需求。
文摘Phase equilibrium in the ternary CuO-PbO-Ag system has been investigated using differential thermal analysis(DTA),thermogravimetry(TG),scanning electron microscopy(SEM) and X-ray diffraction(XRD) techniques.In the ternary CuO-PbO-Ag system,there is a eutectic reaction CuO+PbO+Ag=L at 750℃ and a composition of 12.04 mol.% Ag,16.35 mol.% CuO and 71.61 mol.% PbO.Two miscibility gaps near the two binary tie lines PbO-Ag and CuO-Ag were detected. No binary or ternary compound was detected in the ternary system.SEM and energy dispersive spectroscopy(EDS) confirm the presence of two liquid phases and the eutectic point.
