检索结果-南通市图书馆

A Weld Defect Detection Method Based on Triplet Deep Neural Network

在线全文

学校读者我要写书评

暂无评论

A Weld Defect Detection Method Based on Triplet Deep Neural ...

Latest Scientific Results of China's Lunar and Deep Space Exploration(2022–2024)

第32届中国控制与决策会议

作者： Xiaoyuan liu jinhai liu Fuming Qu Hongfei Zhu Danyu Lu School of Information Science and Engineering Northeastern University

In industrial fields, Nondestructive Testing（NDT） has become an important method to test the quality of welds. For the low-contrast pipe weld defect x-ray image, the traditional detection method has low precision. In this paper, an automatic detection method for weld defects based on a triplet deep neural network is proposed. First, the original X-ray image is changed into a relief image, so that the feature of the defects is more obvious. Second, the feature vector is obtained by mapping the relief image through the triplet deep neural network. The deep neural network based on triplet makes the similar defect feature vectors are closer, and the distances of different defect feature vectors are farther. It is first time that the deep neural network based on triplet was used to detect the weld defect images. Finally, the weld defect was detected by Support Vector Machine（SVM） classifier. It is shown that the proposed detection method of weld defects has better performance than the conventional methods.

关键词： defect detection x-ray triplet loss deep neural network

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

空间科学学报 2024年第4期44卷 622-632页

作者： XU Lin LI Lei liu Jianzhong LIN Honglei LI Yang liu Yang XIE Lianghai ZHANG jinhai QIAO Fuhao HAN Juanjuan ZOU Yongliao General Office of the Lunar and Deep Space Exploration Chinese Academy of SciencesBeijng 100190 State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190 Institute of Geochemistry Chinese Academy of SciencesGuiyang 550081 Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029

China has successfully launched six lunar probes so *** Chang'E-1 to Chang'E-4,they completed the circling,landing and roving exploration,of which Chang'E-4 was the first landing on the far side of the Moon in human ***'E-5 was launched in December 2020,bringing back 1731 g of lunar soil *** the detailed analysis of the samples,the scientists understand the history of late lunar volcanism,specifically extending lunar volcanism by about 800 million to 1 billion years,and proposed possible *** addition,there are many new understandings of space weathering such as meteorite impacts and solar wind radiation on the ***'s first Mars exploration mission Tianwen-1 was successfully launched in July *** the study of scientific data,a number of important scientific achievements have been made in the topography,water environment and shallow surface structure of *** paper introduces the main scientific achievements of Chang'E-4,Chang'E-5 and Tianwen-1 in the past two years,excluding technical and engineering *** to the large number of articles involved,this paper only introduces part of the results.

关键词： Lunar and deep space exploration of China Chang’E-4 mission Chang’E-5 mission Tianwen-1 mission

PRRSV degrades MDA5 via dual autophagy receptors P62 and CCT2 to evade antiviral innate immunity

在线全文

学校读者我要写书评

暂无评论

Virologica Sinica 2024年第2期39卷 264-276页

作者： Ruiqi Sun Yanyu Guo Lilin Zhang Huixia Zhang Boxuan Yin Xiaoyang Li Changyan Li liu Yang Lei Zhang Zexing Li jinhai Huang School of Life Sciences Tianjin UniversityTianjin300072China

Porcine reproductive and respiratory syndrome virus(PRRSV)is a major economically devastating pathogen that has evolved various strategies to evade innate *** of antiviral interferon largely promotes PRRSV immunoevasion by utilizing cytoplasmic melanoma differentiation-associated gene 5(MDA5),a receptor that senses viral *** this study,the downregulated transcription and expression levels of porcine MDA5 in PRRSV infection were observed,and the detailed mechanisms were *** found that the interaction between P62 and MDA5 is enhanced due to two factors:the phosphorylation modification of the autophagic receptor P62 by the upregulated kinase CK2αand the K63 ubiquitination of porcine MDA5 catalyzed by the E3 ubiquitinase TRIM21 in PRRSV-infected *** a result of these modifications,the classic P62-mediated autophagy is ***,porcine MDA5 interacts with the chaperonin containing TCP1 subunit 2(CCT2),which is enhanced by PRRSV *** interaction promotes the aggregate formation and autophagic clearance of MDA5-CCT2-nsp3 independently of *** summary,enhanced MDA5 degradation occurs in PRRSV infection via two autophagic pathways:the binding of MDA5 with the autophagy receptor P62 and the aggrephagy receptor CCT2,leading to intense innate immune *** research reveals a novel mechanism of immune evasion in PRRSV infection and provides fundamental insights for the development of new vaccines or therapeutic strategies.

关键词： Porcine reproductive and respiratory syndrome virus(PRRSV) nsp3 Autophagy MDA5

深厚表土综放采场顶板运动特征实测与数值分析

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

采矿与安全工程学报 2015年第3期32卷 401-406页

作者：郭信山刘金海姜福兴中国矿业大学(北京)资源与安全工程学院北京100083 山东能源集团有限公司山东济南250014 华北科技学院安全工程学院北京101601 北京科技大学土木与环境工程学院北京100083

应用现场实测和数值模拟方法,对深厚表土综放采场顶板运动特征进行系统研究。结果表明:深厚表土综放采场支架载荷的时间效应显著;随着采场推进,直接顶周期性的形成"岩—矸"结构,低位、高位基本顶先后破断并造成采场来压;沿倾斜方向采场... 详细信息

应用现场实测和数值模拟方法,对深厚表土综放采场顶板运动特征进行系统研究。结果表明:深厚表土综放采场支架载荷的时间效应显著;随着采场推进,直接顶周期性的形成"岩—矸"结构,低位、高位基本顶先后破断并造成采场来压;沿倾斜方向采场来压顺序符合一般采场顶板断裂特征;采场支架需控岩层范围大,高位基本顶破断、回转迫使低位基本顶破断、回转造成的采场来压强度大;采场超前应力动态监测技术为采场来压预报提供了一种方法。最后,给出了深厚表土综放采场顶板事故防治的建议。

关键词：综放采场顶板运动深厚表土现场实测数值分析

在线全文

学校读者我要写书评

暂无评论

煤矿冲击地压监测预警技术新进展

煤炭科学技术 2016年第6期44卷 71-77页

作者：刘金海华北科技学院河北省矿井灾害防治重点实验室北京101601

为促进冲击地压监测预警水平的提高和监测预警新技术的推广,阐述了6种冲击地压监测预警技术分类方法及相应分类结果,探讨了冲击地压监测预警在监测参量、预警阈值、测点布置、数据分析等4个方面存在的困难,指出了冲击地压监测预警在监... 详细信息

为促进冲击地压监测预警水平的提高和监测预警新技术的推广,阐述了6种冲击地压监测预警技术分类方法及相应分类结果,探讨了冲击地压监测预警在监测参量、预警阈值、测点布置、数据分析等4个方面存在的困难,指出了冲击地压监测预警在监测范围、监测参数、监测方式、预警参量等4个方面的技术要求,分析了震动场、应力场联合监测技术和"全频广域"震动监测技术,最后介绍了"全频广域"震动监测技术应用案例。结果表明,震动场、应力场联合监测技术和"全频广域"震动监测技术在监测范围、监测参数、监测方式和预警参量等方面能够满足冲击地压监测预警技术要求,具有广阔的应用前景。

关键词：冲击地压监测预警多参量全频广域

基于Markov特征的油气管道泄漏检测与定位方法

在线全文

学校读者我要写书评

暂无评论

仪器仪表学报 2017年第4期38卷 944-951页

作者：刘金海臧东汪刚东北大学信息科学与工程学院沈阳110004

针对传统的基于压力信号的管道泄漏检测方法误报率和漏报率偏高,同时定位误差较大的缺点,设计了一种基于Markov特征的管道泄漏检测与定位方法。首先,将管道压力数据构造为Markov链的形式,并提取其动态特征;然后,将所提取的特征应用于Ney... 详细信息

针对传统的基于压力信号的管道泄漏检测方法误报率和漏报率偏高,同时定位误差较大的缺点,设计了一种基于Markov特征的管道泄漏检测与定位方法。首先,将管道压力数据构造为Markov链的形式,并提取其动态特征;然后,将所提取的特征应用于Neyman-Pearson异常检测方法之中,检测全部压力数据样本的状态,并对检测到的异常样本进行同源信号匹配,修正检测结果;最后,将相似性定位方法与连续小波定位方法结合,确定管道首末两端响应压力变化的时间差,并根据管道长度和压力波传输速度等信息,对泄漏源定位。所提方法能应用于小泄漏和缓慢泄漏的检测与定位,易于实现,误报率与漏报率显著降低,定位精度提高。通过对历史数据的分析,验证了所提方法的可行性和有效性。

关键词：油气管道 Markov链 Neyman-Pearson异常检测相似性定位连续小波定位

Broadband high-efficiency plasmonic metalens with negative dispersion characteristic

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2024年第4期12卷 813-820页

作者： YONG-QIANG liu YONG ZHU HONGCHENG YIN jinhai SUN YAN WANG YONGXING CHE National Key Laboratory of Scattering and Radiation Beijing 100854China

Controlling the dispersion characteristic of metasurfaces(or metalenses) along a broad bandwidth is of great importance to develop high-performance broadband metadevices. Different from traditional lenses that rely on the material refractive index along the light trajectory, metasurfaces or metalenses provide a new regime of dispersion control via a sub-wavelength metastructure, which is known as negative chromatic ***, broadband metalenses design with high-performance focusing especially with a reduced device dimension is a significant challenge in society. Here, we design, fabricate, and demonstrate a broadband highperformance diffractive-type plasmonic metalens based on a circular split-ring resonator metasurface with a relative working bandwidth of 28.6%. The metalens thickness is only 0.09λ0(λ0is at the central wavelength),which is much thinner than previous broadband all-dielectric metalenses. The full-wave simulation results show that both high transmissive efficiency above 80%(the maximum is even above 90%) and high average focusing efficiency above 45%(the maximum is 56%) are achieved within the entire working bandwidth of 9–12 ***, an average high numerical aperture of 0.7(NA = 0.7) of high-efficiency microwave metalens is obtained in the simulations. The broadband high-performance metalens is also fabricated and experimental measurements verify its much higher average focusing efficiency of 55%(the maximum is above 65% within the broad bandwidth) and a moderate high NA of 0.6. The proposed plasmonic metalens can facilitate the development of wavelength-dependent broadband diffractive devices and is also meaningful to further studies on arbitrary dispersion control in diffractive optics based on plasmonic metasurfaces.

关键词： resonator dispersion high

基于AHP-FUZZY综合评价法的回采工艺选择方法

在线全文

学校读者我要写书评

暂无评论

中国矿业 2006年第5期15卷 64-66页

作者：刘金海湖南科技大学能源与安全工程学院湘潭411201

回采工艺的选择是个复杂的模糊决策问题,传统的选择方法———经验类比法具有很大的主观性。本文建立了回采工艺选择的层次结构模型,通过层次分析得到各影响因素权重;应用模糊综合评价法对各回采工艺方式进行综合评价,得到了最优方案。... 详细信息

回采工艺的选择是个复杂的模糊决策问题,传统的选择方法———经验类比法具有很大的主观性。本文建立了回采工艺选择的层次结构模型,通过层次分析得到各影响因素权重;应用模糊综合评价法对各回采工艺方式进行综合评价,得到了最优方案。结果表明:AHP-FUZZY综合评价法能够保证选择结果的客观性,具有操作简单、便于实际应用的优点。

关键词：层次分析模糊综合评价回采工艺方案优选

在线全文

学校读者我要写书评

暂无评论

永磁同步电机dq电感参数新实验获取法

电工技术学报 2014年第7期29卷 97-103页

作者：刘金海陈为胡金高福州大学电气工程与自动化学院福州350116

为改进永磁同步电机dq电感已有实验获取法的不足,本文提出两种新的实验获取法。对应实验接线图,经阻抗解耦分析,求得永磁同步电机终端等效阻抗数学模型。改变转子位置,发现该终端等效阻抗的模为最值时,终端等效电感与dq电感存在特定的... 详细信息

为改进永磁同步电机dq电感已有实验获取法的不足,本文提出两种新的实验获取法。对应实验接线图,经阻抗解耦分析,求得永磁同步电机终端等效阻抗数学模型。改变转子位置,发现该终端等效阻抗的模为最值时,终端等效电感与dq电感存在特定的倍数关系。已有研究表明,传统交流法的交流电枢电流对永磁同步电机dq电感影响较小,因此本文提出的方法可以通过简单手动转动转子及用阻抗测量工具实现dq电感快速有效测量。通过对某永磁同步电机的实际测试,验证了新实验法的有效性与可行性。

关键词：永磁同步电机 dq电感解耦测试