In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the tw...In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the two light beams. Since both light beams are diffracted when passing through the optical systems, the spatial resolution of ghost imaging is in general lower than that of a corresponding conventional imaging system. When Gaussian-shaped light spots are used to illuminate an object, randomly scanning across the object plane, in the ghost imaging scheme, we show th√at by localizing central positions of the spots of the reference light beam, the resolution can be increased by a factor of 2^(1/2) same as that of the corresponding conventional imaging system. We also find that the resolution can be further enhanced by setting an appropriate threshold to the bucket measurement of ghost imaging.展开更多
Based on photogrammetry technology,a novel localization method of micro-polishing robot,which is restricted within certain working space,is presented in this paper.On the basis of pinhole camera model,a new mathematic...Based on photogrammetry technology,a novel localization method of micro-polishing robot,which is restricted within certain working space,is presented in this paper.On the basis of pinhole camera model,a new mathematical model of vision localization of automated polishing robot is established.The vision localization is based on the distance-constraints of feature points.The method to solve the mathematical model is discussed.According to the characteristics of gray image,an adaptive method of automatic threshold selection based on connected components is presented.The center coordinate of the feature image point is resolved by bilinear interpolation gray square weighted algorithm.Finally,the mathematical model of testing system is verified by global localization test.The experimental results show that the vision localization system in working space has high precision.展开更多
A so-called 'local probabilistic Paris relation method' was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds...A so-called 'local probabilistic Paris relation method' was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds were measured statistically and directly by the test data. It was revealed that this method was not reasonable because the test data have seldom a unified level of crack growth rates. Differently,in the presented method the Paris-Erdogan equation was applied to model the local test data around the thresholds. Local probabilistic relations with both the survival probability and the confidence were established on a lognormal distribution of the stress density factors. And then, the probabilistic thresholds were derived from the probabilistic factors with a given critical level of growth rate. An analysis on the test data of LZ50 axle steel for the Chinese railway vehicles verifies that the present method is feasible and available.展开更多
This review hopes to clearly explain the following viewpoints： （1） Neuronal synchronization underlies brain functioning, and it seems possible that blocking excessive synchronization in an epileptic neural network ...This review hopes to clearly explain the following viewpoints： （1） Neuronal synchronization underlies brain functioning, and it seems possible that blocking excessive synchronization in an epileptic neural network could reduce or even control seizures. （2） Local field potential coupling is a very common phenomenon during synchronization in networks. Removal of neurons or neuronal networks that are coupled can significantly alter the extracellular field potential. Interventions of coupling mediated by local field potentials could result in desynchronization of epileptic seizures. （3） The synchronized electrical activity generated by neurons is sensitive to changes in the size of the extracellular space, which affects the efficiency of field potential transmission and the threshold of cell excitability. （4） Manipulations of the field potential fluctuations could help block synchronization at seizure onset.展开更多
齿轮箱的健康监测对于机械传动系统以及机械设备的健康管理极为重要。针对变工况齿轮箱在使用过程中的健康状态较难监测的情况,提出一种基于高斯混合模型(Gaussian mixture model,GMM)和局部分布差异(local distribution difference,LDD...齿轮箱的健康监测对于机械传动系统以及机械设备的健康管理极为重要。针对变工况齿轮箱在使用过程中的健康状态较难监测的情况,提出一种基于高斯混合模型(Gaussian mixture model,GMM)和局部分布差异(local distribution difference,LDD)的自适应动态阈值健康监测方法。首先,对原始振动信号进行处理,从处理信号中提取特征,并依据单调性排序;使用核主成分分析对单调性较好的特征进行降维,构建退化趋势。再使用健康数据训练高斯混合模型,确定模型参数,并计算贝叶斯推断的距离(Bayesian inference distance,BID)。最后使用LDD动态调整滑动窗口大小并结合核密度估计(kernel density estimation,KDE)建立自适应阈值,对齿轮箱的健康状态进行监测。通过实验对比分析表明:本方法的预测准确性为99%,假警率为0.05%,灵敏度为98%,相较于其他方法有较大优势。展开更多
针对视觉结构类似导致的文种相似性问题,基于局部三值模式的相邻共生矩阵(co-occurrence of adjacent local ternary patterns,CoALTP)提出一种具有判别性和鲁棒性的局部三值模式的相邻共生矩阵(discriminant and robust co-occurrence ...针对视觉结构类似导致的文种相似性问题,基于局部三值模式的相邻共生矩阵(co-occurrence of adjacent local ternary patterns,CoALTP)提出一种具有判别性和鲁棒性的局部三值模式的相邻共生矩阵(discriminant and robust co-occurrence of adjacent local ternary patterns,DRCoALTP)方法,用于获取图像纹理。计算文档图像的相邻稀疏局部三值模式(adjacent sparse local ternary patterns,ASLTP),将采样点数量设定为8,以便获得详细的局部纹理,设计出一种基于自适应中值滤波思想的半自适应阈值方法,用于提取灰度图像中心像素周边对角邻域像素的编码值。ASLTP在邻域像素位置存放稀疏局部三值模式(local ternary patterns,LTP)的值,提取灰度共生矩阵(gray-level co-occurrence matrix,GLCM),从4个方向统计使用ASLTP后灰度图像像素之间的频率关系。该算法在阿拉伯文、俄文、简体中文、哈萨克文、藏文、蒙古文、土耳其文、维吾尔文、英文、吉尔吉斯斯坦文和塔吉克斯坦文11个文种的自建印刷体文档图像数据集中验证。试验结果表明,相较于基线和先进的纹理方法,改进后的方法更具判别性,平均识别准确率为99.14%。为改善CoALTP方法可能产生低效分类特征的问题,提出半自适应阈值方法,有效提高识别率并抑制噪声。此外,针对算法产生的高维特征,采用基于均方差的特征选择方法,通过支持向量机(support vector machine,SVM)分类器特征选择后,识别速度提高284%,对11个文种的平均识别准确率达99.44%。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11534008,11605126,and 11804271)the Fund from the Ministry of Science and Technology of China(Grant No.2016YFA0301404)+2 种基金the Natural Science Basic Research Plan in Shaanxi Province,China(Grant No.2017JQ1025)the Doctoral Fund of the Ministry of Education of China(Grant Nos.2016M592772 and 2018M631137)the Fundamental Research Funds for the Central Universities
文摘In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the two light beams. Since both light beams are diffracted when passing through the optical systems, the spatial resolution of ghost imaging is in general lower than that of a corresponding conventional imaging system. When Gaussian-shaped light spots are used to illuminate an object, randomly scanning across the object plane, in the ghost imaging scheme, we show th√at by localizing central positions of the spots of the reference light beam, the resolution can be increased by a factor of 2^(1/2) same as that of the corresponding conventional imaging system. We also find that the resolution can be further enhanced by setting an appropriate threshold to the bucket measurement of ghost imaging.
基金supported by the National High Technology Research and Development Program of China (Grant No. 2006AA04Z214)the National Natural Science Foundation of China (Grant No. 50575092)
文摘Based on photogrammetry technology,a novel localization method of micro-polishing robot,which is restricted within certain working space,is presented in this paper.On the basis of pinhole camera model,a new mathematical model of vision localization of automated polishing robot is established.The vision localization is based on the distance-constraints of feature points.The method to solve the mathematical model is discussed.According to the characteristics of gray image,an adaptive method of automatic threshold selection based on connected components is presented.The center coordinate of the feature image point is resolved by bilinear interpolation gray square weighted algorithm.Finally,the mathematical model of testing system is verified by global localization test.The experimental results show that the vision localization system in working space has high precision.
基金Project supported by the National Natural Science Foundation of China (Nos. 50375130 and 50323003)the Special Foundation for the Authors of National Excellent Doctoral Disserta tions (No. 200234)the Outstanding Young Teachers Program of State Education Ministry (No. 2101)
文摘A so-called 'local probabilistic Paris relation method' was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds were measured statistically and directly by the test data. It was revealed that this method was not reasonable because the test data have seldom a unified level of crack growth rates. Differently,in the presented method the Paris-Erdogan equation was applied to model the local test data around the thresholds. Local probabilistic relations with both the survival probability and the confidence were established on a lognormal distribution of the stress density factors. And then, the probabilistic thresholds were derived from the probabilistic factors with a given critical level of growth rate. An analysis on the test data of LZ50 axle steel for the Chinese railway vehicles verifies that the present method is feasible and available.
基金supported by grants from the National Natural Science Foundation of China,No. 30971534125 Project of the Third Xiangya Hospital of Central South University,China
文摘This review hopes to clearly explain the following viewpoints： （1） Neuronal synchronization underlies brain functioning, and it seems possible that blocking excessive synchronization in an epileptic neural network could reduce or even control seizures. （2） Local field potential coupling is a very common phenomenon during synchronization in networks. Removal of neurons or neuronal networks that are coupled can significantly alter the extracellular field potential. Interventions of coupling mediated by local field potentials could result in desynchronization of epileptic seizures. （3） The synchronized electrical activity generated by neurons is sensitive to changes in the size of the extracellular space, which affects the efficiency of field potential transmission and the threshold of cell excitability. （4） Manipulations of the field potential fluctuations could help block synchronization at seizure onset.
文摘齿轮箱的健康监测对于机械传动系统以及机械设备的健康管理极为重要。针对变工况齿轮箱在使用过程中的健康状态较难监测的情况,提出一种基于高斯混合模型(Gaussian mixture model,GMM)和局部分布差异(local distribution difference,LDD)的自适应动态阈值健康监测方法。首先,对原始振动信号进行处理,从处理信号中提取特征,并依据单调性排序;使用核主成分分析对单调性较好的特征进行降维,构建退化趋势。再使用健康数据训练高斯混合模型,确定模型参数,并计算贝叶斯推断的距离(Bayesian inference distance,BID)。最后使用LDD动态调整滑动窗口大小并结合核密度估计(kernel density estimation,KDE)建立自适应阈值,对齿轮箱的健康状态进行监测。通过实验对比分析表明:本方法的预测准确性为99%,假警率为0.05%,灵敏度为98%,相较于其他方法有较大优势。
文摘针对视觉结构类似导致的文种相似性问题,基于局部三值模式的相邻共生矩阵(co-occurrence of adjacent local ternary patterns,CoALTP)提出一种具有判别性和鲁棒性的局部三值模式的相邻共生矩阵(discriminant and robust co-occurrence of adjacent local ternary patterns,DRCoALTP)方法,用于获取图像纹理。计算文档图像的相邻稀疏局部三值模式(adjacent sparse local ternary patterns,ASLTP),将采样点数量设定为8,以便获得详细的局部纹理,设计出一种基于自适应中值滤波思想的半自适应阈值方法,用于提取灰度图像中心像素周边对角邻域像素的编码值。ASLTP在邻域像素位置存放稀疏局部三值模式(local ternary patterns,LTP)的值,提取灰度共生矩阵(gray-level co-occurrence matrix,GLCM),从4个方向统计使用ASLTP后灰度图像像素之间的频率关系。该算法在阿拉伯文、俄文、简体中文、哈萨克文、藏文、蒙古文、土耳其文、维吾尔文、英文、吉尔吉斯斯坦文和塔吉克斯坦文11个文种的自建印刷体文档图像数据集中验证。试验结果表明,相较于基线和先进的纹理方法,改进后的方法更具判别性,平均识别准确率为99.14%。为改善CoALTP方法可能产生低效分类特征的问题,提出半自适应阈值方法,有效提高识别率并抑制噪声。此外,针对算法产生的高维特征,采用基于均方差的特征选择方法,通过支持向量机(support vector machine,SVM)分类器特征选择后,识别速度提高284%,对11个文种的平均识别准确率达99.44%。
