检索结果-南通市图书馆

基于TSMLZC和SVM的滚动轴承故障检测方法

在线全文

学校读者我要写书评

暂无评论

机电工程 2023年第9期40卷 1326-1335页

作者：卢艳静许艳英包宋建河南师范大学电子与电气工程学院河南新乡453007 三门峡社会管理职业学院信息工程学院河南三门峡472000 重庆科创职业学院人工智能学院重庆402160 重庆文理学院电子信息与电气工程学院重庆402160

滚动轴承故障检测过程中存在故障特征提取困难和分类准确率较低的问题,为此,提出了一种基于时移多尺度Lempel-Ziv复杂度(TSMLZC)和灰狼优化器-支持向量机(GWO-SVM)的滚动轴承故障诊断方法。首先,基于Lempel-Ziv复杂度,提出了一种称为TSM... 详细信息

滚动轴承故障检测过程中存在故障特征提取困难和分类准确率较低的问题,为此,提出了一种基于时移多尺度Lempel-Ziv复杂度(TSMLZC)和灰狼优化器-支持向量机(GWO-SVM)的滚动轴承故障诊断方法。首先,基于Lempel-Ziv复杂度,提出了一种称为TSMLZC的测量信号复杂度的工具,其能够无参数地测量时间序列的复杂度;然后,利用该工具提取了滚动轴承振动信号的TSMLZC值作为故障特征,以表征滚动轴承的不同故障状态;最后,将故障特征输入到基于灰狼优化器的支持向量机分类模型中,对不同滚动轴承的状态进行了准确识别;再将该方法应用于2种实际滚动轴承故障案例,并对5种故障检测方法的诊断结果进行了分析和对比。研究结果表明:与传统的故障诊断模型——多尺度Lempel-ziv复杂度(MLZC)、多尺度熵(MSE)、多尺度模糊熵(MFE)、多尺度排列熵(MPE)相比,TSMLZC+GWO-SVM在2种数据集下分别取得了98.8%和94.4%的诊断准确率,证明了该模型能够适用于滚动轴承的故障诊断;而在诊断滚动轴承的不同负载和工况时,所建立的模型也获得了良好的分类准确率,这表明TSMLZC+GWO-SVM具有较强的竞争力。

关键词：故障特征提取故障分类故障检测准确率时移多尺度Lempel-Ziv复杂度灰狼优化器-支持向量机

Malware Evasion Attacks Against IoT and Other Devices: An Empirical Study

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2024年第1期29卷 127-142页

作者： Yan xu Deqiang Li Qianmu Li Shouhuai xu School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Computer Science Nanjing University of Posts and TelecommunicationsNanjing 210023China Department of Computer Science University of Colorado Colorado SpringsColorado SpringsCO 80918USA

The Internet of Things(loT)has grown rapidly due to artificial intelligence driven edge *** enabling many new functions,edge computing devices expand the vulnerability surface and have become the target of malware ***,attackers have used advanced techniques to evade defenses by transforming their malware into functionality-preserving *** systematically analyze such evasion attacks and conduct a large-scale empirical study in this paper to evaluate their impact on *** specifically,we focus on two forms of evasion attacks:obfuscation and adversarial *** the best of our knowledge,this paper is the first to investigate and contrast the two families of evasion attacks *** apply 10 obfuscation attacks and 9 adversarial attacks to 2870 malware *** obtained findings are as follows.(1)Commercial Off-The-Shelf(COTS)malware detectors are vulnerable to evasion attacks.(2)Adversarial attacks affect COTS malware detectors slightly more effectively than obfuscated malware examples.(3)Code similarity detection approaches can be affected by obfuscated examples and are barely affected by adversarial attacks.(4)These attacks can preserve the functionality of original malware examples.

关键词： Android malware obfuscation adversarial examples

Granting strength to aerogel fibers through encapsulation

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

Science China Materials 2024年第4期67卷 1365-1366页

作者： Wenhui xu Department of Basic Chemistry School of PharmacyJiangxi University of Chinese MedicineNanchang 330004China

Aerogel fibers, distinguished by their lightweight nature, pronounced porosity, large surface area, and superior thermal insulation properties, have diversified applications in thermal management, energy devices, and environmental remediation[1]. However, compared with monolithic ones, these fibershaped aerogels exhibit limited mechanical strength and resilience due to their one-dimensional small size.

关键词： strength fibers thermal

同方期刊数据库

Preface for the Special Issue on“Safety and Intelligent Maintenance of Offshore Structures”

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第2期38卷 181-182页

作者： xu Wan-hai State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China

The ocean serves as a vital carrier for human resource development and economic growth and contains rich mineral resources such as oil,natural gas,polymetallic nodules,cobalt-rich ferromanganese crusts,polymetallic sulfides,and rare earth ***,the ocean has wealthy reserves of wind,wave,tidal,and solar energy,making it an essential strategic space for sustainable future ***,offshore structures are complex.

关键词： ocean offshore tidal

在线全文

学校读者我要写书评

暂无评论

高温环境下碳纤维环氧树脂层压板热响应行为

消防科学与技术 2023年第4期42卷 489-494页

作者：王丹玥徐艳英王志曲芳沈阳航空航天大学安全工程学院辽宁沈阳110136 沈阳航空航天大学辽宁省飞机火爆防控及可靠性适航技术重点实验室辽宁沈阳110136

以碳纤维/环氧树脂层压板为研究对象,利用ABAQUS有限元分析软件对高温环境下碳纤维/环氧树脂层压板热响应过程进行数值模拟,结合试验分析不同铺层厚度材料的热响应行为规律,验证了模拟的可行性。研究发现,随着厚度增加,材料达到稳态温... 详细信息

以碳纤维/环氧树脂层压板为研究对象,利用ABAQUS有限元分析软件对高温环境下碳纤维/环氧树脂层压板热响应过程进行数值模拟,结合试验分析不同铺层厚度材料的热响应行为规律,验证了模拟的可行性。研究发现,随着厚度增加,材料达到稳态温度的时间延后,稳态温度降低,材料内部随着距受热面深度的增加,升温速率呈下降趋势,且随着深度的增大,下降趋势减缓;热流方向沿平行于碳纤维层分布时稳态温度和稳态导热系数均较垂直方向大,碳纤维沿平行于热流传递方向分布有利于传热。

关键词：碳纤维/环氧树脂层压板热响应行为高温环境稳态温度稳态导热系数

From 0D to 3D:Hierarchical structured high-performance free-standing silicon anodes based on binder-induced topological network architecture

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第6期93卷 16-23,I0002页

作者： Yihong Tong Ruicheng Cao Guanghui xu Yifeng Xia Hongyuan xu Hong Jin Hui xu Xi’an Jiaotong University Suzhou Academy Suzhou 215123JiangsuChina Nano Science and Technology Institute University of Science and Technology of ChinaSuzhou 215123JiangsuChina

Free-standing silicon anodes with high proportion of active materials have aroused great attention;however,the mechanical stability and electrochemical performance are severely ***,to resolve the appeal issues,a free-standing anode with a"corrugated paper"shape on micro-scale and a topological crosslinking network on the submicron and nano-scale is ***,an integrated three-dimensional electrode structure is constructed based on robust carbon nanotubes network with firmly anchored SiNPs via forming interlocking *** which,the hierarchical interlocking structure is achieved by directional induction of the binder,which ensures well integration during cycling so that significantly enhances mechanical stability as well as electronic and ionic conductivity of *** from it,this anode exhibits outsta nding performance under harsh service conditions including high Si loading,ultrahigh areal capacity(33.2 mA h cm^(-2)),and high/low temperatures(-15-60℃),which significantly extends its practical ***,the optimization mechanism of this electrode is explored to verify the crack-healing and structure-integration maintaining along cycling via a unique self-stabilization ***,from both the fundamental and engineering views,this strategy offers a promising path to produce high-performance free-standing electrodes for flexible device applications especially facing volume effect challenges.

关键词： Topological network Self-stabilization Flexibility Free-standing Silicon anode

Biotreatment of incinerated bottom ash and biocementation of sand blocks using soybean urease

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第1期25卷 36-46页

作者： Xiaoniu YU Yidong xu Jiangsu Key Laboratory of Construction Materials Southeast UniversityNanjing211189China School of Civil Engineering and Architecture NingboTech UniversityNingbo315100China

Because of the high cost of cultivating urease-producing bacteria(UPB),this paper proposes soybean-urease-induced carbonate precipitation(SUICP)as a novel biocement for treatment of nickel contaminants and cementation of sandy *** found the optimal soaking time and soybean-powder content to be 30 min and 130 g/L,respectively,based on a standard of 5 U of urease *** most efficient removal of nickel ions is obtained with an ideal mass ratio of urea to nickel ions to soybean-powder filtrate(SPF)of 1:2.4:*** removal efficiency of nickel ions can reach 89.42%when treating 1 L of nickel-ion solution(1200 mg/L with the optimal mass ratio).In incinerated bottom ash(IBA),the removal efficiency of nickel ions is 99.33%with the optimal mass *** biocemented sandy soil,the average unconfined compressive strength(UCS)of sand blocks cemented with soybean urease-based biocement can reach 118.89 kPa when the cementation level is ***,the average content of CaCO_(3)in sand blocks is 2.52%.As a result,the SUICP process can be applied to remove heavy metal ions in wastewater or solid waste and improve the mechanical properties of soft soil foundations.

关键词： Biocement Soybean-powder filtrate(SPF) Removal efficiency Sandy soil Unconfined compressive strength(UCS)

Superior compound coatings prepared by low-temperature vanadium-nitrocarburizing duplex treatment

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

Rare Metals 2024年第4期43卷 1828-1835页

作者： Gen Jin Fang-Fang xu xun-xun Hu Yue xu School of Chemistry Beihang UniversityBeijing100191China Guobiao(Beijing)Testing and Certification Co. LtdBeijing100088China School of Materials Science and Engineering Beihang UniversityBeijing100191China

Superior compound coatings were prepared on CK45 steel surface by vanadium-nitrocarburizing duplex treatment in low-temperature salt *** this study,the microhardness,the phase constitution and the compositional distribution in the coatings prepared under different conditions were systematically *** results indicated that the reactions among activated vanadium,carbon and nitrogen atoms occurred on the steel surface,leading to the formation of compound coatings composed of outermost and compound *** mechanism for the formation of compound layer as well as the growth kinetics of the layer was also *** the duplex treatment,the wear and corrosion resistances of steel surface were significantly *** was found that the growth kinetics of compound layer obeyed the parabolic law,with the activation energy of 122.82 kJ·moL^(-1).

关键词： Vanadium-nitrocarburizing duplex treatment Compound coatings Microstructure Formation mechanism Growth kinetics

Study on force chain evolution of rice straw with different length during vibrational compression

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第2期85卷 310-322页

作者： Han Tang Wenlong xu Guixuan Zhu Changsu xu Jinwu Wang College of Engineering Northeast Agricultural UniversityHarbin150030China

This paper explores the mechanism of force chain evolution and voidage change under vibrational and non-vibrational compression conditions of rice straw of different *** were used to explore the force chain evolution and voidage variation mechanism under different *** re-sults show that under non-vibrational compression,the strong force chain passes from top to bottom in vertical direction and from center to periphery in tangential *** vibrational compression,the force chain passes from top and bottom to center in vertical direction and the force chain evolves from outer ring to interior and exterior in tangential *** number of strong chains,voidage and standard deviation of the mean pressure under vibratory compression are lower than the values under non-vibratory *** promotes stress transfer and enhancement,velocity enhancement and density *** study analyzes the mechanical properties of different lengths straw during vibrational and non-vibrational compression from a detailed viewpoint.

关键词： Straw compression Voidage Discrete element method Mechanical properties Force chain transmission