变压器油中溶解气体体积分数是表征变压器健康状态及故障特性的重要参量。因此,准确预测变压器油中溶解气体的体积分数,有助于及时把握变压器的状态演化与故障发展趋势。现有对气体体积分数预测的研究多集中在点预测方面,难以全面反映...变压器油中溶解气体体积分数是表征变压器健康状态及故障特性的重要参量。因此,准确预测变压器油中溶解气体的体积分数,有助于及时把握变压器的状态演化与故障发展趋势。现有对气体体积分数预测的研究多集中在点预测方面,难以全面反映气体体积分数的不确定性信息。针对此问题,提出了一种基于灰狼优化长短期记忆网络(long short⁃term memory based on grey wolf optimization,GWO⁃LSTM)与非参数核密度估计(non⁃parametric kernel density estimation,NKDE)的变压器油中溶解气体体积分数点—区间联合预测方法。首先,搭建变压器油中溶解气体体积分数点—区间联合预测模型的整体结构,阐述预测的实现过程;其次,利用自适应噪声完备集合经验模态分解方法将气体体积分数原始序列分解成若干个较为平缓的子序列,再基于GWO⁃LSTM对上述子序列分别进行点预测,并将所有子序列点预测结果叠加合成还原为气体体积分数点预测结果;然后,基于气体体积分数点预测结果及NKDE构造气体体积分数预测误差的概率密度估计函数,进而生成不同置信水平下的区间预测结果;最后,对所提方法进行算例分析,算例结果验证了所提方法的有效性。展开更多
目的探讨海洛因依赖对大脑灰质结构的作用,分析吸食海洛因总时间、吸食海洛因总量、每日吸食海洛因量等因素对脑灰质体积产生的影响。资料与方法采用MRI对17例海洛因依赖者和15名健康受试者行3D结构像扫描,所得数据用基于体素的形态学分...目的探讨海洛因依赖对大脑灰质结构的作用,分析吸食海洛因总时间、吸食海洛因总量、每日吸食海洛因量等因素对脑灰质体积产生的影响。资料与方法采用MRI对17例海洛因依赖者和15名健康受试者行3D结构像扫描,所得数据用基于体素的形态学分析(voxel based morphometry,VBM)方法分析脑灰质体积,并比较两组之间的体积差异;分析脑灰质体积与吸食海洛因总时间、吸食海洛因总量、每日吸食海洛因量之间的相关关系。结果与健康被试者相比,海洛因依赖者右侧眶额回、中央前回、左侧岛叶、扣带回、枕叶舌回灰质体积减少(P<0.005);控制年龄、受教育程度、每日吸烟量后,脑灰质体积变化与使用海洛因总时间、海洛因总量、每日吸食海洛因量之间无显著相关关系。结论长期吸食海洛因导致脑灰质结构损害,主要涉及认知控制、情感、视觉控制等相关脑区。展开更多
The aim of the current study was to use whole brain voxel-based morphometry（VBM）to assess the gray matter（GM）changes in unmedicated patients with obsessive-compulsive disorder（OCD）compared with normal controls.W...The aim of the current study was to use whole brain voxel-based morphometry（VBM）to assess the gray matter（GM）changes in unmedicated patients with obsessive-compulsive disorder（OCD）compared with normal controls.We compared the GM volumes in28 patients with 22 matched healthy controls using a1.5T MRI.Three-dimensional T1-weighted magnetic resonance images were obtained from all participants.VBM was performed to detect GM volume differences between the two groups.We detected increased regional GM volumes in the bilateral middle temporal gyri,bilateral middle occipital gyri,bilateral globus pallidus,right inferior parietal gyrus,left superior parietal gyrus,right parahippocampus,right supramarginal gyrus,right medial superior frontal gyrus,and left inferior frontal opercular cortex in the OCD patients relative to controls（P〈0.001,uncorrected,cluster size〉100 voxels）.No decreased GM volume was found in the OCD group compared with normal controls.Our findings suggest that structural changes in the GM are not limited to fronto-striato-thalamic circuits in the pathogenesis of OCD.Temporo-parietal cortex may also play an important role.展开更多
Memristive technology has been widely explored, due to its distinctive properties, such as nonvolatility, high density,versatility, and CMOS compatibility. For memristive devices, a general compact model is highly fav...Memristive technology has been widely explored, due to its distinctive properties, such as nonvolatility, high density,versatility, and CMOS compatibility. For memristive devices, a general compact model is highly favorable for the realization of its circuits and applications. In this paper, we propose a novel memristive model of TiOx-based devices, which considers the negative differential resistance（NDR） behavior. This model is physics-oriented and passes Linn＇s criteria. It not only exhibits sufficient accuracy（IV characteristics within 1.5% RMS）, lower latency（below half the VTEAM model）,and preferable generality compared to previous models, but also yields more precise predictions of long-term potentiation/depression（LTP/LTD）. Finally, novel methods based on memristive models are proposed for gray sketching and edge detection applications. These methods avoid complex nonlinear functions required by their original counterparts. When the proposed model is utilized in these methods, they achieve increased contrast ratio and accuracy（for gray sketching and edge detection, respectively） compared to the Simmons model. Our results suggest a memristor-based network is a promising candidate to tackle the existing inefficiencies in traditional image processing methods.展开更多
An effective damage test method based on a marker-based watershed algorithm with gray control(MWGC) is proposed to study the properties of damage induced by near-field laser irradiation for large-aperture laser facili...An effective damage test method based on a marker-based watershed algorithm with gray control(MWGC) is proposed to study the properties of damage induced by near-field laser irradiation for large-aperture laser facilities.Damage tests were performed on fused silica samples and information on the size of damage sites was obtained by this new algorithm,which can effectively suppress the issue of over-segmentation of images resulting from non-uniform illumination in darkfield imaging.Experimental analysis and results show that the lateral damage growth on the exit surface is exponential,and the number of damage sites decreases sharply with damage site size in the damage site distribution statistics.The average damage growth coefficients fitted according to the experimental results for Corning-7980 and Heraeus-Suprasil312 samples at 351 nm are 1.10 ± 0.31 and 0.60 ± 0.09,respectively.展开更多
文摘变压器油中溶解气体体积分数是表征变压器健康状态及故障特性的重要参量。因此,准确预测变压器油中溶解气体的体积分数,有助于及时把握变压器的状态演化与故障发展趋势。现有对气体体积分数预测的研究多集中在点预测方面,难以全面反映气体体积分数的不确定性信息。针对此问题,提出了一种基于灰狼优化长短期记忆网络(long short⁃term memory based on grey wolf optimization,GWO⁃LSTM)与非参数核密度估计(non⁃parametric kernel density estimation,NKDE)的变压器油中溶解气体体积分数点—区间联合预测方法。首先,搭建变压器油中溶解气体体积分数点—区间联合预测模型的整体结构,阐述预测的实现过程;其次,利用自适应噪声完备集合经验模态分解方法将气体体积分数原始序列分解成若干个较为平缓的子序列,再基于GWO⁃LSTM对上述子序列分别进行点预测,并将所有子序列点预测结果叠加合成还原为气体体积分数点预测结果;然后,基于气体体积分数点预测结果及NKDE构造气体体积分数预测误差的概率密度估计函数,进而生成不同置信水平下的区间预测结果;最后,对所提方法进行算例分析,算例结果验证了所提方法的有效性。
文摘目的探讨海洛因依赖对大脑灰质结构的作用,分析吸食海洛因总时间、吸食海洛因总量、每日吸食海洛因量等因素对脑灰质体积产生的影响。资料与方法采用MRI对17例海洛因依赖者和15名健康受试者行3D结构像扫描,所得数据用基于体素的形态学分析(voxel based morphometry,VBM)方法分析脑灰质体积,并比较两组之间的体积差异;分析脑灰质体积与吸食海洛因总时间、吸食海洛因总量、每日吸食海洛因量之间的相关关系。结果与健康被试者相比,海洛因依赖者右侧眶额回、中央前回、左侧岛叶、扣带回、枕叶舌回灰质体积减少(P<0.005);控制年龄、受教育程度、每日吸烟量后,脑灰质体积变化与使用海洛因总时间、海洛因总量、每日吸食海洛因量之间无显著相关关系。结论长期吸食海洛因导致脑灰质结构损害,主要涉及认知控制、情感、视觉控制等相关脑区。
基金supported by the National High Technology Research and Development Program (863 Program) of China (2007AA02Z420)a Key Project of the Science and Technology Commission of Shanghai Municipality (074119520)+4 种基金the Program for Shanghai Outstanding Academic Leader Plans (08XD14036)the National Key Clinical Disciplines at Shanghai Mental Health Center (Office of Medical Affairs, Ministry of Health, 2011873 OMA-MH, 2011-873)a Guidance Project of the Shanghai Science and Technology Commission, China (124119a8200)the Medical Engineering Crossover Research Fund Program of Shanghai Jiao Tong University (YG2012MS59)
文摘The aim of the current study was to use whole brain voxel-based morphometry（VBM）to assess the gray matter（GM）changes in unmedicated patients with obsessive-compulsive disorder（OCD）compared with normal controls.We compared the GM volumes in28 patients with 22 matched healthy controls using a1.5T MRI.Three-dimensional T1-weighted magnetic resonance images were obtained from all participants.VBM was performed to detect GM volume differences between the two groups.We detected increased regional GM volumes in the bilateral middle temporal gyri,bilateral middle occipital gyri,bilateral globus pallidus,right inferior parietal gyrus,left superior parietal gyrus,right parahippocampus,right supramarginal gyrus,right medial superior frontal gyrus,and left inferior frontal opercular cortex in the OCD patients relative to controls（P〈0.001,uncorrected,cluster size〉100 voxels）.No decreased GM volume was found in the OCD group compared with normal controls.Our findings suggest that structural changes in the GM are not limited to fronto-striato-thalamic circuits in the pathogenesis of OCD.Temporo-parietal cortex may also play an important role.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61332003 and 61303068)the Natural Science Foundation of Hunan Province,China(Grant No.2015JJ3024)
文摘Memristive technology has been widely explored, due to its distinctive properties, such as nonvolatility, high density,versatility, and CMOS compatibility. For memristive devices, a general compact model is highly favorable for the realization of its circuits and applications. In this paper, we propose a novel memristive model of TiOx-based devices, which considers the negative differential resistance（NDR） behavior. This model is physics-oriented and passes Linn＇s criteria. It not only exhibits sufficient accuracy（IV characteristics within 1.5% RMS）, lower latency（below half the VTEAM model）,and preferable generality compared to previous models, but also yields more precise predictions of long-term potentiation/depression（LTP/LTD）. Finally, novel methods based on memristive models are proposed for gray sketching and edge detection applications. These methods avoid complex nonlinear functions required by their original counterparts. When the proposed model is utilized in these methods, they achieve increased contrast ratio and accuracy（for gray sketching and edge detection, respectively） compared to the Simmons model. Our results suggest a memristor-based network is a promising candidate to tackle the existing inefficiencies in traditional image processing methods.
文摘An effective damage test method based on a marker-based watershed algorithm with gray control(MWGC) is proposed to study the properties of damage induced by near-field laser irradiation for large-aperture laser facilities.Damage tests were performed on fused silica samples and information on the size of damage sites was obtained by this new algorithm,which can effectively suppress the issue of over-segmentation of images resulting from non-uniform illumination in darkfield imaging.Experimental analysis and results show that the lateral damage growth on the exit surface is exponential,and the number of damage sites decreases sharply with damage site size in the damage site distribution statistics.The average damage growth coefficients fitted according to the experimental results for Corning-7980 and Heraeus-Suprasil312 samples at 351 nm are 1.10 ± 0.31 and 0.60 ± 0.09,respectively.
