The macro mechanical properties of materials with characteristics of large scale and complicated structural composition can be analyzed through its reconstructed meso-structures.In this work,the meso-structures of tal...The macro mechanical properties of materials with characteristics of large scale and complicated structural composition can be analyzed through its reconstructed meso-structures.In this work,the meso-structures of talus deposits that widely exist in the hydro-power engineering in the southwest of China were first reconstructed by small particles according to the in-situ photographs based on the self-adaptive PCNN digital image processing,and then numerical direct shear tests were carried out for studying the mechanical properties of talus deposits.Results indicate that the reconstructed meso-structures of talus deposits are more consistent with the actual situation because the self-adaptive PCNN digital image processing has a higher discrimination in the details of soil-rock segmentation.The existence and random distribution of rock blocks make the initial shear stiffness,the peak strength and the residual strength higher than those of the "pure soil" with particle size less than 1.25 cm apparently,but reduce the displacements required for the talus deposits reaching its peak shear strength.The increase of rock proportion causes a significant improvement in the internal friction angle of talus deposit,which to a certain degree leads to the characteristics of shear stress-displacement curves having a changing trend from the plastic strain softening deformation to the nonlinear strain hardening deformation,while an unconspicuous increase in cohesion.The uncertainty and heterogeneity of rock distributions cause the differences of rock proportion within shear zone,leading to a relatively strong fluctuation in peak strengths during the shear process,while movement features of rock blocks,such as translation,rotation and crossing,expand the scope of shear zone,increase the required shear force,and also directly lead to the misjudgment that the lower shear strength is obtained from the samples with high rock proportion.That,however,just explains the reason why the shear strength gained from a small amount of indoor test data is not consistent with engineering practice.展开更多
Speckle filtering of synthetic aperture radar (SAR) images while preserving the spatial signal variability (texture and fine structures) still remains a challenge. Many algorithms have been proposed for the SAR imager...Speckle filtering of synthetic aperture radar (SAR) images while preserving the spatial signal variability (texture and fine structures) still remains a challenge. Many algorithms have been proposed for the SAR imagery despeckling. However, simulated annealing (SA) methods is one of excellent choices currently. A critical problem in the study on SA is to provide appropriate cooling schedules that ensure fast convergence to near-optimal solutions. This paper gives a new necessary and sufficient condition for the cooling schedule so that the algorithm state converges in all probability to the set of global minimum cost states. Moreover, it constructs an appropriate objective function for SAR image despeckling. An experimental result of the actual SAR image processing is obtained.展开更多
明暗恢复形状(shape from shading,SFS)算法是三维重建中不可缺少的关键技术。该方法通过单幅图像中物体的灰度的亮度信息,求出每个点的相对高度和表面法向量,现有的SFS线性化算法利用泰勒级数进行展开忽略了高阶部分的影响,导致三维重...明暗恢复形状(shape from shading,SFS)算法是三维重建中不可缺少的关键技术。该方法通过单幅图像中物体的灰度的亮度信息,求出每个点的相对高度和表面法向量,现有的SFS线性化算法利用泰勒级数进行展开忽略了高阶部分的影响,导致三维重建的图像不够精确等问题。为解决三维重建精度问题,本文提出一种基于SFS算法改进的高精度快速水下图像三维重建方法,在提高三维重建精度的前提下,解决了对本轮数据利用率不够、迭代速度慢等问题。将其应用在真实图像和虚拟图像上进行实验评估以及三维重建的量化分析,验证了相比于经典SFS线性化算法和SFS最小化算法,本文提出的SFS算法改进的高精度快速水下图像三维重建方法,取得了令人满意的信噪比和图像信息熵值。展开更多
目的颗粒的堆积高度反映了包装袋的填充密度,堆积高度越大,则填充密度越小;反之,填充密度越大。探究不同振动参数(振动时间、振动频率、振动幅度和振动方向)对颗粒堆积高度的影响规律,以提高包装袋的填充密度。方法基于DEM(Discrete Ele...目的颗粒的堆积高度反映了包装袋的填充密度,堆积高度越大,则填充密度越小;反之,填充密度越大。探究不同振动参数(振动时间、振动频率、振动幅度和振动方向)对颗粒堆积高度的影响规律,以提高包装袋的填充密度。方法基于DEM(Discrete Element Method),利用EDEM数值模拟软件建立PET颗粒堆积模型,并通过Matlab图像处理技术与实验相结合验证模型的准确性;在此模型基础上,仿真模拟颗粒在静止和振动状态下的堆积行为。结论竖直方向的振动更能降低颗粒的堆积高度,增大填充密度;随着振动时间的延长,颗粒的堆积高度逐渐降低,随后趋于平稳,最大可降低约17.70%;随着振动频率的增加,颗粒的堆积高度显著降低,最大可降低约16.67%;随着振动幅度的减小,颗粒的堆积高度逐渐降低,最大可降低约18.59%。结果通过改变振动皮带机的振动参数,可以有效提升包装袋的颗粒填充密度。展开更多
基金Project(2013BAB06B00) supported by the National Key Technology R&D Programof ChinaProject(2011CB013504) supported by the National Basic Research Program of ChinaProject(50911130366) supported by the National Natural Science Foundation of China
文摘The macro mechanical properties of materials with characteristics of large scale and complicated structural composition can be analyzed through its reconstructed meso-structures.In this work,the meso-structures of talus deposits that widely exist in the hydro-power engineering in the southwest of China were first reconstructed by small particles according to the in-situ photographs based on the self-adaptive PCNN digital image processing,and then numerical direct shear tests were carried out for studying the mechanical properties of talus deposits.Results indicate that the reconstructed meso-structures of talus deposits are more consistent with the actual situation because the self-adaptive PCNN digital image processing has a higher discrimination in the details of soil-rock segmentation.The existence and random distribution of rock blocks make the initial shear stiffness,the peak strength and the residual strength higher than those of the "pure soil" with particle size less than 1.25 cm apparently,but reduce the displacements required for the talus deposits reaching its peak shear strength.The increase of rock proportion causes a significant improvement in the internal friction angle of talus deposit,which to a certain degree leads to the characteristics of shear stress-displacement curves having a changing trend from the plastic strain softening deformation to the nonlinear strain hardening deformation,while an unconspicuous increase in cohesion.The uncertainty and heterogeneity of rock distributions cause the differences of rock proportion within shear zone,leading to a relatively strong fluctuation in peak strengths during the shear process,while movement features of rock blocks,such as translation,rotation and crossing,expand the scope of shear zone,increase the required shear force,and also directly lead to the misjudgment that the lower shear strength is obtained from the samples with high rock proportion.That,however,just explains the reason why the shear strength gained from a small amount of indoor test data is not consistent with engineering practice.
基金ThisprojectwassupportedbytheNationalNaturalScienceFoundationofChina (No .6 98310 40 )
文摘Speckle filtering of synthetic aperture radar (SAR) images while preserving the spatial signal variability (texture and fine structures) still remains a challenge. Many algorithms have been proposed for the SAR imagery despeckling. However, simulated annealing (SA) methods is one of excellent choices currently. A critical problem in the study on SA is to provide appropriate cooling schedules that ensure fast convergence to near-optimal solutions. This paper gives a new necessary and sufficient condition for the cooling schedule so that the algorithm state converges in all probability to the set of global minimum cost states. Moreover, it constructs an appropriate objective function for SAR image despeckling. An experimental result of the actual SAR image processing is obtained.
文摘明暗恢复形状(shape from shading,SFS)算法是三维重建中不可缺少的关键技术。该方法通过单幅图像中物体的灰度的亮度信息,求出每个点的相对高度和表面法向量,现有的SFS线性化算法利用泰勒级数进行展开忽略了高阶部分的影响,导致三维重建的图像不够精确等问题。为解决三维重建精度问题,本文提出一种基于SFS算法改进的高精度快速水下图像三维重建方法,在提高三维重建精度的前提下,解决了对本轮数据利用率不够、迭代速度慢等问题。将其应用在真实图像和虚拟图像上进行实验评估以及三维重建的量化分析,验证了相比于经典SFS线性化算法和SFS最小化算法,本文提出的SFS算法改进的高精度快速水下图像三维重建方法,取得了令人满意的信噪比和图像信息熵值。
文摘目的颗粒的堆积高度反映了包装袋的填充密度,堆积高度越大,则填充密度越小;反之,填充密度越大。探究不同振动参数(振动时间、振动频率、振动幅度和振动方向)对颗粒堆积高度的影响规律,以提高包装袋的填充密度。方法基于DEM(Discrete Element Method),利用EDEM数值模拟软件建立PET颗粒堆积模型,并通过Matlab图像处理技术与实验相结合验证模型的准确性;在此模型基础上,仿真模拟颗粒在静止和振动状态下的堆积行为。结论竖直方向的振动更能降低颗粒的堆积高度,增大填充密度;随着振动时间的延长,颗粒的堆积高度逐渐降低,随后趋于平稳,最大可降低约17.70%;随着振动频率的增加,颗粒的堆积高度显著降低,最大可降低约16.67%;随着振动幅度的减小,颗粒的堆积高度逐渐降低,最大可降低约18.59%。结果通过改变振动皮带机的振动参数,可以有效提升包装袋的颗粒填充密度。
