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Automated identification of steel weld defects, a convolutional neural network improved machine learning approach

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FRONTIERS OF STRUCTURAL AND CIVIL ENGINEERING 2024年第2期18卷 294-308页

作者： Shu, zhan Wu, Ao Si, Yuning Dong, Hanlin Wang, Dejiang Li, yifan Shanghai Univ Sch Mech & Engn Sci Shanghai 200444 Peoples R China Shanghai Normal Univ Sch Civil Engn Shanghai 201418 Peoples R China Shanghai PinlanData Technol Co Ltd Shanghai 200072 Peoples R China

This paper proposes a machine-learning-based methodology to automatically classify different types of steel weld defects, including lack of the fusion, porosity, slag inclusion, and the qualified (no defects) cases. This methodology solves the shortcomings of existing detection methods, such as expensive equipment, complicated operation and inability to detect internal defects. The study first collected percussed data from welded steel members with or without weld defects. Then, three methods, the Mel frequency cepstral coefficients, short-time Fourier transform (STFT), and continuous wavelet transform were implemented and compared to explore the most appropriate features for classification of weld statuses. Classic and convolutional neural network-enhanced algorithms were used to classify, the extracted features. Furthermore, experiments were designed and performed to validate the proposed method. Results showed that STFT achieved higher accuracies (up to 96.63% on average) in the weld status classification. The convolutional neural network-enhanced support vector machine (SVM) outperformed six other algorithms with an average accuracy of 95.8%. In addition, random forest and SVM were efficient approaches with a balanced trade-off between the accuracies and the computational efforts.

关键词： steel weld machine learning convolutional neural network weld defect detection classification task percussion SOUND CLASSIFICATION FUSION

Comparison of conventional and inverted structures in fullerene-free organic solar cells

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Journal of Energy Chemistry 2015年第6期24卷 744-749页

作者： yifan Wang Huitao Bai Xiaowei zhan Beijing National Laboratory for Molecular Sciences Institute of ChemistryChinese Academy of Sciences University of Chinese Academy of Sciences Department of Materials Science and Engineering College of EngineeringKey Laboratory of Polymer Chemistry and Physics of Ministry of EducationPeking University

A n-type small molecule DC-IDT2E with 4,4,9,9-tetrakis（4-hexylphenyl）-indaceno[1,2-b：5,6-bt]dithiophene as a central building block, furan as rr-bridges, and 1,1 -dicyanomethylene-3-indanone as end acceptor groups, was synthesized and used as an electron acceptor in solution-processed organic solar cells （OSCs）. DC-IDT2F exhibited good thermal stability, broad and strong absorption in 500-850 rim, a narrow bandgap of 1.54 eV, LUMO of-3.88 eV, HOMO of-5.44 eV and an electron mobility of 6.5 × 10-4 cm2/（V.s）. DC-IDT2F-based OSCs with conventional and inverted structures exhibited power conversion efficiencies of 2.26 and 3.08% respec- tively. The effect of vertical phase separation and morphology of the active layer on the device performance in the two structures was studied.

关键词： Organic solar cells Non-fullerene acceptors Fullerene free Vertical phase separation Inverted structure

Effect of ultrasonic modification on the protective activity of Flammulina velutipes polysaccharide to prevent ethanol-induced injury on GES-1 cells

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Food Science and Human Wellness 2023年第6期12卷 2451-2459页

作者： Jinrong Xiao Xin Chen Jingsi zhang yifan Wang Lei Zhong Qiping zhan Qiuhui Hu Liyan Zhao College of Food Science and Technology Nanjing Agricultural UniversityNanjing 210095China College of Food Science and Engineering Nanjing University of Finance and EconomicsNanjing 210023China

Flammulina velutipes(F.velutipes)polysaccharides were modified by ultrasound at the rated power of 150 W and 900 W.The monosaccharide composition,ultraviolet-visible,and Fourier transform infrared spectral characteristics of F.velutipes polysaccharides(FVP)and their ultrasonic modification products(U-FVPs)were determined.The protective effects of FVP and U-FVPs on human gastric mucosal cells GES-1 were confi rmed for the first time.The mole ratios of glucose and galactose were decreased and the mole ratio of mannose was increased after ultrasonic modification.Compared with the original FVP and the FVP modifi ed by ultrasound of 150 W(U-FVP1),the FVP modifi ed by ultrasound of 900 W(U-FVP2)could better prevent ethanol-induced damage to GES-1 cells.With increasing ultrasound intensity,the protective effect of FVPs on GES-1 cells was significantly enhanced by more effective prevention of intracellular reactive oxygen species(ROS)production and more promotion of expression of triglyceride factor 2(TFF2),prostaglandin E2(PGE2),epidermal growth factor(EGF),and transforming growth factorβ1(TGF-β1)mRNA.The ultrasonic modifi cation might be an effective way to develop novel F.velutipes polysaccharides that could effectively resist the gastric injury caused by excessive alcohol consumption.

关键词： Flammulina velutipes polysaccharide Ultrasonic modification GES-1 cell Gastric ulcer Ethanol-induced injury

CCR2 enhances CD25 expression by FoxP3^(+) regulatory T cells and regulates their abundance independently of chemotaxis and CCR2^(+) myeloid cells

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Cellular & Molecular Immunology 2020年第2期17卷 123-132页

作者： Yifan Zhan Nancy Wang Ajithkumar Vasanthakumar Yuxia zhang Michael Chopin Stephen L.Nutt Axel Kallies Andrew M.Lew The Walter&Eliza Hall Institute of Medical Research ParkvilleVIC 3052Australia Department of Medical Biology University of MelbourneParkvilleVIC 3010Australia Guangzhou Institute of Paediatrics Guangzhou Women and Children’s Medical CentreGuangzhou Medical University510623 GuangzhouGuangdongChina Department of Microbiology and Immunology Peter Doherty Institute for Infection and ImmunityUniversity of MelbourneParkvilleVIC 3010Australia

A wide array of chemokine receptors,including CCR2,are known to control Treg migration.Here,we report that CCR2 regulates Tregs beyond chemotaxis.We found that CCR2 deficiency reduced CD25 expression by FoxP3^(+) Treg cells.Such a change was also consistently present in irradiation chimeras reconstituted with mixed bone marrow from wild-type(WT)and CCR2−/−strains.Thus,CCR2 deficiency resulted in profound loss of CD25 ^(hi) FoxP3^(+) Tregs in secondary lymphoid organs as well as in peripheral tissues.CCR2−/−Treg cells were also functionally inferior to WT cells.Interestingly,these changes to Treg cells did not depend on CCR2+monocytes/moDCs(the cells where CCR2 receptors are most abundant).Rather,we demonstrated that CCR2 was required for TLR-stimulated,but not TCR-or IL-2-stimulated,CD25 upregulation on Treg cells.Thus,we propose that CCR2 signaling can increase the fitness of FoxP3^(+) Treg cells and provide negative feedback to counter the proinflammatory effects of CCR2 on myeloid cells.

关键词： CCR2 CD25 organs

Influence of lanthanum on enhancement of mechanical and electrical properties of Cu-Al_2O_3 composites

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Journal of Rare Earths 2019年第5期37卷 534-540页

作者： Yifan Zhang Zhen Ji Chengchang Jia Guimin Liu Farong Wan Qian zhan School of Materials Science and Engineering University of Science and Technology Beijing Faculty of Remanufacturing Engineering Academy of Armored Forces Engineering

Two kinds of Cu-Al_2O_3 composites(with and without La) were prepared via mechanical alloying-spark plasma sintering(MA-SPS) method. Microstructure, mechanical properties and electrical resistivity were investigated systematically using metallography, scanning electron microscopy, transmission electron microscopy, mechanical and electrical properties testing. The results indicate that an appropriate amount of La can homogenize the distribution of Al_2O_3. As such, yield strength, ultimate tensile strength and elongation of Cu-Al_2O_3-La are greatly increased. Some semi-coherent interface between Cu and Al_2O_3 is found, which means a low interface energy. The grain shape of Cu changes to irregular band with the addition of La. This change results in a density decrease of grain boundary and reduces electrical resistance. Lanthanum may exist in the form of La_2O_3.

关键词： Cu-Al2O3 composite Lanthanum Mechanical alloying Spark plasma sintering Electrical resistivity Rare earths

Significantly Enhanced Performance of g-C3N4/Bi2MoO6 Films for Photocatalytic Degradation of Pollutants Under Visible-light Irradiation

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Chemical Research in Chinese Universities 2016年第2期32卷 284-290页

作者： LIU Yujun ZHOU Feng zhan Su YANG yifan YIN Yanfeng Transportation Equipment and Ocean Engineering College Dalian Maritime University Dalian 116026 P. R. China

The films of photocatalysts have been widely used in decomposition pollutants. In this study, the films were successfully prepared from Bi2MoO6 and g-C3N4/Bi2MoO6 by a simple method, respectively. The samples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FTIR）, photoluminescence（PL）, UV-Vis diffuse reflectance spectroscopy（DRS） and electrochemical experiments to investigate crystalline structure, morphology, composition and properties. The photocatalytic activity of the photocatalyst films for the pollutants was evaluated by degradation of methylene blue（MB） in aqueous solution under visible light irradiation. Experiments revealed that the film of g-C3Na/Bi2MoO6 exhibited higher photocatalytic ability compared to the single-component photocatalyst, and proved its stability. The superior catalytic performance can be attributed to the effective separation of electron-hole pairs and the reduced rate of recombination. This work is of great value for the preparation of photocatalysts films.

关键词： Film g-C3N4 Bi2MoO6 Photocatalyst

理解数字赋能行政审批制度改革:“技术—结构—制度”三维视角

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江海学刊 2024年第2期 140-151页

作者：詹国彬陈逸凡南京审计大学公共管理学院

数字技术赋能行政审批制度改革既是传统行政审批制度改革的迭代升级,也是“放管服”改革中最为重要的有机组成部分,更是一场以数字技术为驱动力、以政府组织结构变革为基础、以政府管理制度创新为手段、以人民为中心的政府改革运动。中... 详细信息

数字技术赋能行政审批制度改革既是传统行政审批制度改革的迭代升级,也是“放管服”改革中最为重要的有机组成部分,更是一场以数字技术为驱动力、以政府组织结构变革为基础、以政府管理制度创新为手段、以人民为中心的政府改革运动。中央政府推动的“放管服”改革和数字中国战略为数字赋能行政审批制度改革提供了强有力的政治支持。苏浙沪(两省一市)政府在贯彻落实“放管服”改革过程中开展了卓有成效的探索,形成了富有特色的创新模式。引入“技术—结构—制度”三维视角,构建“技术嵌入—结构重塑—制度创新”的分析框架,有助于揭示和理解数字赋能行政审批制度改革的发生机理和行动逻辑。数字赋能行政审批制度改革有力地推动了以“政府为中心”的治理范式向“以人民为中心”的治理范式转变,即便在全球范围内也堪称公共管理改革与创新的典范。这场根植于中国场景的政府改革不仅对促进我国政府治理体系和治理能力现代化有重要价值,也为数字时代全球公共管理改革与创新贡献了中国方案。

关键词： “放管服”改革数字赋能行政审批制度改革 “技术—结构—制度”三维视角

Rapid Phase Ambiguity Elimination Methods for DOA Estimator via Hybrid Massive MIMO Receive Array

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Chinese Journal of Electronics 2023年

作者： zhan Xichao SUN Zhongwen SHU Feng CHEN Yiwen CHENG Xin WU Yuanyuan zhanG Qi LI yifan zhanG Peng Hainan University Nanjing University of Science and Technology

For a sub-connected hybrid multiple-input multiple-output(MIMO) receiver with K subarrays and N antennas, there exists a challenging problem of how to rapidly remove phase ambiguity in only single time-slot. First, a DOA estimator of maximizing received power(Max-RP) is proposed to find the maximum value of K-subarray output powers, where each subarray is in charge of one sector, and the center angle of the sector corresponding to the maximum output is the estimated true DOA. To make an enhancement on precision, MaxRP plus quadratic interpolation(Max-RP-QI) method is designed. In the proposed Max-RP-QI, a quadratic interpolation scheme is adopted to interpolate the three DOA values corresponding to the largest three receive powers of Max-RP. Finally, to achieve the CRLB, a Root-MUSIC plus Max-RP-QI scheme is developed. Simulation results show that the proposed three methods eliminate the phase ambiguity during one time-slot and also show lowcomputational-complexities. In particular, the proposed Root-MUSIC plus Max-RP-QI scheme can reach the CRLB, and the proposed Max-RP and Max-RP-QI are still some performance losses 2d B～4d B compared to the CRLB.

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Rapid Phase Ambiguity Elimination Methods for DOA Estimator via Hybrid Massive MIMO Receive Array

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Chinese Journal of Electronics 2024年第1期33卷 175-184页

作者： Xichao zhan Zhongwen SUN Feng SHU Yiwen CHEN Xin CHENG Yuanyuan WU Qi zhanG yifan LI Peng zhanG School of Information and Communication Engineering Hainan University School of Electronic and Optical Engineering Nanjing University of Science and Technology

For a sub-connected hybrid multiple-input multiple-output(MIMO) receiver with K subarrays and N antennas, there exists a challenging problem of how to rapidly remove phase ambiguity in only single time-slot. A direction of arrival(DOA) estimator of maximizing received power(Max-RP) is proposed to find the maximum value of K-subarray output powers, where each subarray is in charge of one sector, and the center angle of the sector corresponding to the maximum output is the estimated true DOA. To make an enhancement on precision, Max-RP plus quadratic interpolation(Max-RP-QI) method is designed. In the proposed Max-RP-QI, a quadratic interpolation scheme is adopted to interpolate the three DOA values corresponding to the largest three receive powers of Max-RP.To achieve the Cramer Rao lower bound, a Root-MUSIC plus Max-RP-QI scheme is developed. Simulation results show that the proposed three methods eliminate the phase ambiguity during one time-slot and also show low computational complexities. The proposed Root-MUSIC plus Max-RP-QI scheme can reach the Cramer Rao lower bound,and the proposed Max-RP and Max-RP-QI are still some performance losses 2–4 d B compared to the Cramer Rao lower bound.

关键词： Hybrid analog and digital Direction of arrival Massive hybrid multiple-input multiple-output Phase ambiguity Low computational complexity