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基于指数调节策略对抗网络学习的轴承故障诊断研究

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振动工程学报 2024年第3期37卷 476-484页

作者：田静沈长青陈再刚石娟娟江星星朱忠奎西南交通大学轨道交通运载系统全国重点实验室四川成都610031 苏州大学轨道交通学院车辆工程系江苏苏州215131

基于深度学习的故障诊断方法被广泛应用于以轴承为代表的机械关键部件故障诊断,其取得理想效果的前提是有足量故障样本且训练集、测试集满足同分布要求。然而,在实际工况下数据分布会发生变化,进而使原有工况下的诊断模型很难适用于新... 详细信息

基于深度学习的故障诊断方法被广泛应用于以轴承为代表的机械关键部件故障诊断,其取得理想效果的前提是有足量故障样本且训练集、测试集满足同分布要求。然而,在实际工况下数据分布会发生变化,进而使原有工况下的诊断模型很难适用于新工况。为此,域适应类迁移学习方法被用于解决训练集、测试集分布不同的问题,其重点在于实现数据分布适应,即度量数据分布差异,并利用度量结果对模型训练进行指导,从而提升学习效率和诊断准确率。在此基础上,提出了一种基于对抗学习的域适应方法,该方法的核心是将提出的指数调节策略与对抗网络相结合,使得网络在故障诊断过程中更有针对性地适应目标域的数据分布。该网络由特征提取器、分类器、一个全局域鉴别器和多个局部域鉴别器组成,利用对抗策略和适应性矩估计算法对模型进行优化,并通过基于指数调节策略设定的指数自适应因子对模型中的边缘分布和条件分布重要性进行调节,使得模型可以稳定、高效地进行故障诊断。在跨转速、跨负载和同时跨转速和负载的轴承诊断案例中对提出的方法进行验证,结果表明本文方法的诊断效果优于其他域适应方法,并具有较好的稳定性。

关键词：故障诊断轴承域适应对抗学习

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国内外卫生技术评估方法指南的系统评价

中国循证医学杂志 2024年第9期24卷 1021-1029页

作者：吴雪景城阳施兰君廖星中国中医科学院中医临床基础医学研究所循证医学基础研究室北京100700

目的系统评价国内外已发表的卫生技术评估(health technology assessment,HTA)方法指南。方法全面检索国内外常用数据库、指南数据库、国际HTA机构/组织网络、代表性国家HTA网络或政府卫生部门官方网站,搜集HTA实施或报告规范类文献,检... 详细信息

目的系统评价国内外已发表的卫生技术评估(health technology assessment,HTA)方法指南。方法全面检索国内外常用数据库、指南数据库、国际HTA机构/组织网络、代表性国家HTA网络或政府卫生部门官方网站,搜集HTA实施或报告规范类文献,检索时限均为建库至2023年4月24日。采用系统评价方法,对纳入指南的基础信息、HTA实施步骤、评估指标、报告清单等信息进行提取,最后综合分析与描述。结果本研究共纳入指南41篇,发表时间为2002年1月至2023年1月;发表机构涉及23个国家/国际组织;发表文献涉及6种语言;评估对象主要是所有卫生技术(n=23)、药品(n=4)、诊断/检测技术(n=4)、非药品卫生技术(n=3)、医疗器械/设备(n=3)、医院卫生技术(n=2)、医疗和外科手术的干预措施(n=1)、筛查技术(n=1);评估视角主要是卫生体系视角(n=16)、全社会视角(n=12)、医院视角(n=3),其余未提供评估视角信息;有28篇指南描述了详细HTA评估流程,涉及HTA评估步骤11个;有39篇指南详细介绍了评估领域与相关评估指标,涵盖评估领域2~9个不等,涉及一级评估指标10个;有10篇指南列出了HTA报告清单,涉及报告条目18个;报告了利益冲突的指南为17篇,大多为不存在利益冲突(n=10),剩余7篇文献中有3篇未说明具体利益冲突,4篇文献中表明了可能的利益冲突来源。结论HTA发展至今国际上已经形成了相对完善的评估体系,但目前需要统一卫生技术分类标准和报告规范,完善不同类型卫生技术评估的特异性指标,明确评估视角。同时结合我国HTA发展现状,制订本土化的HTA实施与报告指南,为合理配置卫生资源的决策,提供科学信息和方法基础。

关键词：卫生技术评估实施步骤评估指标报告清单指南系统评价

Unraveling the potential-dependent degradation mechanism in Fe–N–C catalysts for oxygen reduction reaction

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Science China Chemistry 2024年

作者： Yuyi Chu Yuqing Cheng Pengbo Wang Jingsen Bai Xin Guan Shuo Wang Chang Lan Hongxiang Wu Zhaoping shi Siyuan Zhu Wei Liu Changpeng Liu Meiling Xiao Wei xing State Key Laboratory of Electroanalytic Chemistry Jilin Province Key Laboratory of Low Carbon Chemistry Power Changchun Institute of Applied Chemistry Chinese Academy of Sciences School of Applied Chemistry and Engineering University of Science and Technology of China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences

Fe–N–C is hailed as the most promising candidate for replacing costly platinum-based catalysts for proton-exchange membrane fuel cells(PEMFCs) owing to their impressive catalytic activity and low cost. However, the durability of Fe–N–C catalysts remains a major challenge, primarily due to an insufficient understanding of their degradation mechanisms. In this study, we monitor the real-time changes in the electrode during the oxygen reduction reaction(ORR), shedding light on the potentialdependent degradation mechanisms inherent to Fe–N–C catalysts. Utilizing in-situ differential electrochemical mass spectroscopy, we identify three distinct potential regions with varying degrees of performance loss, notably observing carbon corrosion signals at low potentials. Theoretical calculations and fluorescence probe experiments corroborate that degradation mechanisms at high potentials are primarily driven by strong oxidative potentials that overcome the carbon oxidation energy barrier, whereas the degradation at low potentials is predominantly caused by the high concentrations of reactive oxygen species(ROS) generated during the ORR. The potential-dependent carbon corrosion consequently leads to a similar dependence of demetallation of active sites on the working potential. This study offers a comprehensive understanding of the intrinsic interrelations among various degradation mechanisms, thus paving the way for enhancing the durability of Fe–N–C catalysts in PEMFC applications.

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哈特曼-夏克波前传感器高精度球面波标定方法研究

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中国光学（中英文） 2024年第3期17卷 521-527页

作者：包明帝史国华邢利娜何益中国科学技术大学生物医学工程学院(苏州) 江苏苏州215163 中国科学院苏州生物医学工程技术研究所江苏苏州215163

为解决哈特曼-夏克波前传感器传统标定方法存在的测量精度低、稳定性不足等问题,提出了一种基于球面波的哈特曼-夏克波前传感器高精度绝对标定方法。通过理论推导获取了球面波的高精度标定方法,结合搭建的球面波标定实验装置,对子孔径数... 详细信息

为解决哈特曼-夏克波前传感器传统标定方法存在的测量精度低、稳定性不足等问题,提出了一种基于球面波的哈特曼-夏克波前传感器高精度绝对标定方法。通过理论推导获取了球面波的高精度标定方法,结合搭建的球面波标定实验装置,对子孔径数为128×128的哈特曼-夏克波前传感器完成高精度标定。该方法计算得到了哈特曼-夏克波前传感器结构参数f,w以及L_(0)的精确值。对标定后的哈特曼-夏克波前传感器的测量精度进行测试,实验结果表明,经本文方法标定后的哈特曼-夏克波前传感器的波前复原精度达到了PV=1.376×10^(-2)λ,RMS=4×10^(-3)λ(λ=625 nm),重复性精度为PV=3.2×10^(-3)λ,RMS=9.76×10^(-4)λ(λ=625 nm)。该方法可以为大口径的SHWFS完成高精度标定,提升测量精度。

关键词：哈特曼-夏克波前传感器绝对标定球面波前

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Anisotropic s-Wave Gap in the Vicinity of a Quantum Critical Point in Superconducting BaFe_(2)(As_(1-x)P_(x))_(2) Single Crystals:A Study of Point-Contact Spectroscopy

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Chinese Physics Letters 2024年第4期41卷 118-123页

作者：詹红星林玉尺赵宇清左海艳王兴玉马肖燕李春红罗会仟陈根富李世亮任聪 School of Physics and Astronomy Yunnan UniversityKunming 650500China Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190China Yunnan Key Laboratory for Electromagnetic Materials and Devices Yunnan UniversityKunming 650500China

We report on soft c-axis point-contact Andreev reflection(PCAR)spectroscopy combining with resistivity measurements on BaFe_(2)(As_(0.7)P_(0.3))_(2),to elucidate the superconducting gap structure in the vicinity of the quantum critical point.A double peak at the gap edge plus a dip feature at zero-bias has been observed on the PCAR spectra,indicative of the presence of a nodeless gap in BaFe_(2)(As_(0.7)P_(0.3))_(2).Detailed analysis within a sophisticated theoretical model reveals an anisotropic gap with deep gap *** PCARs also feature additional structures related to the electron-bosonic coupling *** the extracted superconducting energy gap value,a characteristic bosonic energy Ω_(b) and its temperature dependence are obtained,comparable with the spin-resonance energy observed in neutron scattering *** results indicate a magnetism-driven quantum critical point in the BaFe_(2)(As_(1-x)P_(x))_(2) system.

关键词： quantum critical resistivity

内抹调湿砂浆外墙吸放湿特性及对负荷影响分析

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湖南大学学报（自然科学版） 2024年第1期51卷 225-236页

作者：龚光彩王洪顺刘永超石星湖南大学土木工程学院湖南长沙410082

本文从建筑围护结构节能出发,以内抹WSE(木质纤维Wood fibre、海泡石Sepio⁃lite、膨胀珍珠岩Expanded perlite)基复合调湿保温砂浆外墙为研究对象,将其与内抹普通砂浆外墙对比,分析吸放湿特性及其对负荷的影响.研究使用COMSOL Multiphys... 详细信息

本文从建筑围护结构节能出发,以内抹WSE(木质纤维Wood fibre、海泡石Sepio⁃lite、膨胀珍珠岩Expanded perlite)基复合调湿保温砂浆外墙为研究对象,将其与内抹普通砂浆外墙对比,分析吸放湿特性及其对负荷的影响.研究使用COMSOL Multiphysics有限元软件的建筑材料热湿耦合模型,分析环境湿度变化与外墙之间的湿迁移变化,以及与外墙的传热传质.以夏热冬冷典型气候地区长沙为例,分析内抹WSE基复合调湿保温砂浆外墙的负荷及潜热负荷占比,同时选取夏热冬暖地区广州和寒冷地区北京对比分析外墙的全年能耗.研究发现,内抹WSE基复合调湿保温砂浆外墙的吸放湿速率远大于内抹普通砂浆的外墙,并能长时间保持高速的吸放湿状态,同时比内抹普通砂浆墙体节省22.31%~23.85%的全年负荷.墙体在吸湿过程中,温升与吸湿速率能力体现出一致性,表明墙体内表面湿迁移对温度有着重要影响,并且湿迁移越大对温度影响越大.墙体在放湿过程中,温度迅速下降是放湿速率快的表现.内抹WSE基复合调湿保温砂浆墙体具有优良的吸放湿特性和节能潜力,可用于建筑围护结构节能.

关键词：外墙建筑材料吸放湿特性湿度控制围护结构负荷

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Adaptive Space Expansion for Fast Motion Planning

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1499-1514页

作者： Shenglei shi Jiankui Chen State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The sampling process is very inefficient for sam-pling-based motion planning algorithms that excess random sam-ples are generated in the planning *** this paper,we pro-pose an adaptive space expansion(ASE)approach which belongs to the informed sampling category to improve the sampling effi-ciency for quickly finding a feasible *** ASE method enlarges the search space gradually and restrains the sampling process in a sequence of small hyper-ellipsoid ring subsets to avoid exploring the unnecessary ***,for a con-structed small hyper-ellipsoid ring subset,if the algorithm cannot find a feasible path in it,then the subset is ***,the ASE method successively does space exploring and space expan-sion until the final path has been ***,we present a particular construction method of the hyper-ellipsoid ring that uniform random samples can be directly generated in *** last,we present a feasible motion planner BiASE and an asymptoti-cally optimal motion planner BiASE*using the bidirectional exploring method and the ASE *** demon-strate that the computation speed is much faster than that of the state-of-the-art *** source codes are available at https://***/shshlei/ompl.

关键词： Adaptive space expansion(ASE) hyper-ellipsoid ring informed sampling motion planning.

No Reference Image Sharpness Assessment Based on Global Color Difference Variation

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Chinese Journal of Electronics 2024年第1期33卷 293-302页

作者： Chenyang shi Yandan LIN School of Artificial Intelligence Anhui Polytechnic University School of Mechanical Engineering Anhui Polytechnic University Department of Light Sources and Illuminating Engineering Fudan University Academy for Engineering & Technology Fudan University

Image quality assessment(IQA) model is designed to measure the image quality in consistent with subjective ratings by computational models. In this research, a valid no reference IQA(NR-IQA) model for color image sharpness assessment is proposed based on local color difference map in a color space. In the proposed model, the absolute color difference variation and relative color difference variation are combined to evaluate sharpness in YIQ color space(a color coordinate system for the development of the United States color television system). The difference between sharpest and blurriest spot of an image is represented by the absolute color difference variation, and relative color difference variation expresses the variation in the image content. Extensive experiments are performed on five publicly available benchmark synthetic blur databases and two real blur databases, and the results prove that the proposed model work better than the other state-of-the-art and latest NR-IQA models for the prediction accuracy on blurry images. Besides, the model maintains the lowest computational complexity.

关键词： Image quality TV Image color analysis Databases Computational modeling Color Predictive models

An uncertainty investigation for liner impedance eduction methods

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Chinese Journal of Aeronautics 2024年第3期37卷 49-59页

作者： Weihao shi Xiaodong JING School of Energy and Power Engineering Beihang UniversityBeijing 100191China

Impedance eduction methods have been developed for decades to meet the increasing need for high-quality impedance data in the design and optimization of acoustic *** this end,it is important to fully investigate the uncertainty problem,to which only limited attention has been devoted so *** paper considers the possibility of acoustically-induced structural vibration as a nonnegligible uncertainty or error source in impedance eduction *** the frequency moves away from the resonant frequency,with the increase in the value of cavity reactance,the acoustic particle velocity inside liner orifices possibly decreases to the extent comparable to the vibration velocity of liner facing ***,the acoustically-induced vibration,although generally being weak except at the inherent structural frequencies,may considerably affect the impedance eduction results near the anti-resonant frequency where the liner has poor *** demonstrate the effect of structural vibration,the vibration velocity of liner facing sheet is estimated from the experimentally educed admittance of the liner samples whose orifices are sealed with ***,a three-dimensional numerical model is set up,in which normal particle velocity is introduced over the solid portion of liner facing sheet to imitate structural vibration,rather than directly solving the acoustic-structural coupling *** shown by the results,the vibration of liner facing sheet,whose velocity is as small as estimated by the experiment,can result in anomalous deviation of the educed impedance from the impedance model near the anti-resonant *** trend that the anomalous deviation varies with frequency is numerically captured.

关键词： Impedance eduction Uncertainty analysis Acoustically-induced structural vibration Anti-resonant frequency Perforated liner