检索结果-南通市图书馆

Condition monitoring and fault diagnosis strategy of railway point machines using vibration signals

在线全文

学校读者我要写书评

暂无评论

Transportation Safety and Environment 2023年第2期5卷 27-37页

作者： Yongkui Sun Yuan Cao Haitao Liu weifeng yang Shuai Su National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong UniversityBeijing 100044China CRRC Zhuzhou Institute Co Ltd Zhuzhou 412001HunanChina Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong UniversityBeijing 100044China

Condition monitoring of railway point machines is important for train operation safety and *** to the fields of mechanical equipment fault detection,this paper proposes a fault detection and identification strategy of railway point machines via vibration signals.A comprehensive feature distilling approach by combining variational mode decomposition(VMD)energy entropy and time-and frequency-domain statistical features is presented,which is more effective than single type of *** optimal set of features was selected with ReliefF,which helps improve the diagnosis *** vector machine(SVM),which is suitable for a small sample,is adopted to realize *** diagnosis accuracy of the proposed method reaches 100%,and its effectiveness is verified by experiment *** this paper,vibration signals are creatively adopted for fault diagnosis of railway point *** presented method can help guide field maintenance staff and also provide reference for fault diagnosis of other equipment.

关键词： railway point machines condition monitoring variational mode decomposition(VMD)energy entropy statistical features

Energy band alignment of 2D/3D MoS_(2)/4H-SiC heterostructure modulated by multiple interfacial interactions

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2023年第1期18卷 153-164页

作者： Huili Zhu Zifan Hong Changjie Zhou Qihui Wu Tongchang Zheng Lan yang Shuqiong Lan weifeng yang Xiamen Key Laboratory of Ultra-Wide Bandgap Semiconductor Materials and Devices Department of PhysicsSchool of ScienceJimei UniversityXiamen 361021China Department of Microelectronics and Integrated Circuit School of Electronic Science and Engineering(National Model Microelectronics College)Xiamen UniversityXiamen 361005China School of Marine Equipment and Mechanical Engineering Jimei UniversityXiamen 361021China

The interfacial properties of MoS_(2)/4H-SiC heterostructures were studied by combining first-principles calculations and X-ray photoelectron ***(theoretical)valence band offsets(VBOs)increase from 1.49(1.46)to 2.19(2.36)eV with increasing MoS_(2) monolayer(1L)up to 4 layers(4L).A strong interlayer interaction was revealed at 1L MoS_(2)/SiC *** level pinning and totally surface passivation were realized for 4H-SiC(0001)*** 0.96e per unit cell transferring forms an electric field from SiC to MoS_(2).Then,1L MoS_(2)/SiC interface exhibits type I band alignment with the asymmetric conduction band offset(CBO)and *** 2L and 4L MoS_(2)/SiC,Fermi level was just pinning at the lower MoS_(2)*** interaction keeps weak vdW interaction between upper and lower MoS_(2) *** exhibit the type II band alignments and the enlarged CBOs and VBOs,which is attributed to weak vdW interaction and strong interlayer orbital coupling in the multilayer MoS_(2).High efficiency of charge separation will emerge due to the asymmetric band alignment and built-in electric field for all the MoS_(2)/SiC *** multiple interfacial interactions provide a new modulated perspective for the next-generation electronics and optoelectronics based on the 2D/3D semiconductors heterojunctions.

关键词： MoS_(2) SiC X-ray photoelectron spectroscopy band alignment first-principles calculations

Overburden failure and the prevention of water and sand inrush during coal mining under thin bedrock

在线全文

学校读者我要写书评

暂无评论

Mining Science and Technology 2011年第5期21卷 733-736页

作者： yang weifeng Xia Xiaohong Zhao Guorong Ji Yubin Shen Dingyi School of Resources and Geosdences China University of Mining ＆ Technology Xuzhou 221116 China

Coal mining under thin bedrock or thick unconsolidated soil layers brings mining problems related to these special geological conditions. The meaning of the term ''thin bedrock'' is defined through the thick- ness statistics of the coal seam and the bedrock layer. The coal-bearing strata having thick, unconsoli- dated aquifers and thin bedrock located at the Taiping Coal Mine in Shandong province were taken as a geological prototype for subsequent study. The geological, hydro-geological and engineering character- istics of the thin bedrock were analyzed. An engineering geological model was than established. Overbur- den failure and the development of ''Three Zones'' were studied by physical model tests. The rupture pattern and rock failure were analyzed for mining conditions under thin bedrock. The height of the caving zone and the freely flowing water fractured zone of different mining thicknesses were separately calcu- lated. The results show that a mining thickness greater than 3.5 m causes the height of the freely flowing water fractured zone to be sufficient to touch the weathered zone and the bottom of the Quaternary sys- tem aquifer, to various degrees. This, then, would lead to water and sand inrush into the working face. Measures to prevent water and sand flow inrush disasters by eliminating the power source are put fore- word. A field dewatering scheme was designed and observational data were obtained. The dewatering project had an obvious effect and the water level at working face number 8309 dropped to a safe level. The average draw down of the groundwater was observed to be 7.86 m. This showed that the dewatering project played a role in decreasing the hydraulic pressure and ensuring safety mining.

关键词： Thin bedrockMining failureWater and sand flow inrushDewatering

在线全文

学校读者我要写书评

暂无评论

城市轨道交通列车虚拟联挂技术研究

控制与信息技术 2024年第4期 108-115页

作者：杨卫峰雷成健韩琛李启翮谢星中车株洲电力机车研究所有限公司湖南株洲412001 湖南中车时代通信信号有限公司湖南长沙410100

列车虚拟联挂技术是借助先进的无线通信、传感定位和协同控制等技术,通过控制相邻列车间的运行速度和间隔距离,形成一个协调逻辑整体,完成列车编队的共同控制与调度组织,该技术已经逐渐成为轨道交通列车运行控制系统的发展方向。文章综... 详细信息

列车虚拟联挂技术是借助先进的无线通信、传感定位和协同控制等技术,通过控制相邻列车间的运行速度和间隔距离,形成一个协调逻辑整体,完成列车编队的共同控制与调度组织,该技术已经逐渐成为轨道交通列车运行控制系统的发展方向。文章综述了国内外的城轨列车虚拟联挂技术的发展概况及技术现状,分析了实现城市轨道交通列车虚拟联挂的关键技术,包括高性能的车车通信技术、基于相对制动的安全防护技术、基于自主感知的防撞技术、多传感融合列车定位技术以及协同控制技术等;并指出其工程应用中所面临的技术挑战,如更好的协同控制算法、更优的车车通信机制,以及更完善的安全制动模型等。

关键词：轨道交通列车编组虚拟联挂车车通信协同控制精准定位分布式控制

维普期刊数据库博看期刊

Distribution patterns of 210Po, 210Pb and the particle export in the Taiwan Strait during the winter

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2020年第2期39卷 12-21页

作者： Lihao Zhang weifeng yang Min Chen Yinian Zhu Zhou Wang Ziming Fang Yusheng Qiu Yanhong LiGuangxi Key Laboratory of Environmental Pollution Control Theory and Technology Guilin University ofTechnologyGuilin 541004China State Key Laboratory of Marine Environmental Science/College of Ocean and Earth Sciences Xiamen UniversityXiamen 361102China

210Po and 210Pb are increasingly used to constrain particle dynamics in the open oceans,however they are less used in coastal ***,distributions and partitions of 210Po and 210Pb were examined in the Taiwan Strait,as well as their application to quantify particle *** concentrations of dissolved 210Po and 210Pb(<0.6μm)ranged from 1.21 to 7.63 dpm/(100 L)and from 1.07 to 6.33 dpm/(100 L),*** concentrations of particulate 210Po and 210Pb varied from 1.96 to 36.74 dpm/(100 L)and from 3.11 to 38.06 dpm/(100 L).Overall,particulate 210Po and 210Pb accounted for the majority of the bulk 210Po and 210Pb.210Po either in dissolved or particulate phases showed similar spatial patterns to 210Pb,indicating similar mechanisms for controlling the distributions of 210Po and 210Pb in the Taiwan *** different fractionation coefficients indicated that particles in the Zhemin Coastal Current(ZCC)inclined to absorb 210Po prior to 210Pb while they showed an opposite effect in the Taiwan Warm Current(TWC).Based on the disequilibria between 210Po and 210Pb,the sinking fluxes of total particulate matter(TPM)were estimated to range from–0.22 to 3.84 g/(m2·d),showing an overall comparable spatial distribution to previous reported sediment accumulation ***,our sinking fluxes were lower than the sedimentation rates,indicating a sediment resuspension in winter and horizontal transport of particulate matter from the Taiwan Strait to the East China Sea.

关键词： Taiwan Strait 210Po 210Pb resuspension export flux sedimentation

Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2008年第1期27卷 29-41页

作者： LU E ZHANG Lei CHEN Min QIU Yusheng XING Na yang weifeng LI Yanping HUANG Yipu Department of Oceanography Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China

Surface water was collected from the Jiulong Estuary for determination of activity concentrations of uranium isotopes in different size fractions, namely, greater than 53, 10 -53, 2 - 10, 0.4 -2 μm, 10 000 u -0.4 μm and less than 10 000 u fractions by microfihration and cross-flow uhrafiltration technologies. Results indicated that most of the dissolved uranium （〈 0.4 μm） exis- ted in the low molecular mass fraction （〈 10 000 u）, and the colloidal uranium-238 （10 000 u -0.4 μm） only contributed less than 1% of the dissolved uranium-238. The fractions of colloidal uranium in the dissolved phases decreased with the increasing sa- linity. A positive linear relationship between uranium-238 activities and salinities was observed for the dissolved, colloidal and low molecular mass fractions, indicating a conservative behavior of uranium in the Jiulong Estuary. In the particulate phases （〉 0.4 μm）, the partitioning of uranium isotopes among different size fractions was controlled by the partitioning of particle concentrations. In the regions with salinities below 20, the partitioning of uranium-238 among different size fractions was as follows： 10 - 53 μm 〉 2 - 10 μm 〉 0.4 - 2 μm greater than above 53 μm. However, the order at the offshore station with salinities above 30 changed as follows ： 0.4 - 2 μm 〉 10 - 53 μm 〉 2 - 10 μm greater than above 53 μm. The fraction of the 0.4 - 2 μm particles increased at the offshore station, suggesting the increased contribution of the authigenic uranium. The activity ratio of uranium-234 to uranium-238 in the dissolved phases, including the low molecular mass fraction and the colloidal fraction, was larger than unity, showing the occurrence of excess uranium-234. In contrast, the activity ratio of uranium-234 to uranium-238 in all size fractions of the particulate phase was close to the equilibrium value （1.0）. The observed different values of the activity ratio of uranium-234 to uranium-238 in the dissolved phase and the particulat

关键词： uranium isotopes size fractionation Jiulong Estuary in China

在线全文

学校读者我要写书评

暂无评论

基于同位素的极区海洋生物泵运转及机制研究

极地研究 2024年第3期36卷 343-351页

作者：陈敏范玲芳王博陈阳军张润方仔铭杨伟锋郑敏芳陈梦雅厦门大学海洋与地球学院福建厦门361102 山东科技大学安全与环境工程学院山东青岛266590 江苏海洋大学海洋科学与水产学院江苏连云港222005

生物泵是极区海洋净吸收大气CO_(2)的重要路径之一,也是连接海洋上层和底栖生态系统的关键环节。本文概述近10年来应用放射性核素和稳定同位素的独特指示功能,系统地开展普里兹湾、阿蒙森海、宇航员海、白令海、楚科奇海和加拿大海盆等... 详细信息

生物泵是极区海洋净吸收大气CO_(2)的重要路径之一,也是连接海洋上层和底栖生态系统的关键环节。本文概述近10年来应用放射性核素和稳定同位素的独特指示功能,系统地开展普里兹湾、阿蒙森海、宇航员海、白令海、楚科奇海和加拿大海盆等南北极海域生物泵运转规律及维系机制的研究,探究了生物固碳、颗粒有机碳输出、有机物降解、营养盐再生和有机物埋藏等过程的动力学特征及空间变化规律,揭示了淡水组分、颗粒物浓度和痕量营养盐Fe等环境因子对生物泵的影响。研究发现,海冰融水、冰川融水/河水等淡水组分通过改变水体层化、光可获得性和营养盐供给等影响了生物固碳速率、Fe吸收速率和颗粒有机碳(POC)输出通量的空间变化;有机物降解及硝化作用主导着营养盐再生过程;南极底层水形成和颗粒物跨陆架输送影响生物泵的表-底耦合状况。同时,面对未来气候变化和人类活动的双重压力,亟待加强生物泵与食物网相互作用的研究,以准确掌握极区海洋生态系统变化的规律及机制。

关键词：海洋生物泵放射性核素稳定同位素南大洋北冰洋

含龙胆草提取物的液体敷料联合依巴斯汀治疗面部敏感性皮肤的疗效及其对皮肤生理功能的影响

在线全文

学校读者我要写书评

暂无评论

中国美容医学 2024年第5期33卷 79-82页

作者：于军强李力翠王晓茹毛伟杨祎峰藁城市人民医院药剂科河北石家庄052160 藁城市人民医院皮肤科河北石家庄052160 藁城市人民医院医务科河北石家庄052160 藁城市人民医院中医科河北石家庄052160

目的:探讨含龙胆草提取物的液体敷料联合依巴斯汀治疗面部敏感性皮肤的疗效及其对皮肤生理功能的影响。方法:按照随机数字表法将2021年10月-2022年12月笔者医院收治的90例面部敏感性皮肤患者分为对照组与观察组,每组45例。对照组使用依... 详细信息

目的:探讨含龙胆草提取物的液体敷料联合依巴斯汀治疗面部敏感性皮肤的疗效及其对皮肤生理功能的影响。方法:按照随机数字表法将2021年10月-2022年12月笔者医院收治的90例面部敏感性皮肤患者分为对照组与观察组,每组45例。对照组使用依巴斯汀治疗,观察组使用含龙胆草提取物的液体敷料联合依巴斯汀治疗,均连续治疗4周。比较两组的疗效,乳酸刺激试验指标,皮肤生理功能指标[经皮水分丢失量(Transepidermal water loss,TEWL)、皮脂含量、角质层含水量、皮肤pH值]及不良反应。结果:治疗结束后,观察组的总有效率(93.33%vs 71.11%)明显高于对照组(P<0.05);两组乳酸刺激试验指标,皮肤生理功能指标均治疗前明显改善(P<0.05);观察组乳酸刺痛评分明显低于对照组(P<0.05),乳酸刺痛感开始时间明显长于对照组(P<0.05);观察组TEWL、皮肤pH值明显低于对照组(P<0.05),皮脂含量、角质层含水量明显高于对照组(P<0.05)。两组均无严重不良反应发生。结论:含龙胆草提取物的液体敷料联合依巴斯汀能明显提高面部敏感性皮肤的临床疗效,明显改善皮肤生理功能及耐受性,安全性好。

关键词：面部敏感性皮肤龙胆草提取物液体敷料依巴斯汀皮肤生理功能

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

基于一二维耦合模型的洪水风险区划研究

江西水利科技 2024年第2期50卷 79-85页

作者：谢信东(文/翻译) 李德龙李光锦杨伟峰江西省水利科学院江西南昌330029 江西省鄱阳湖流域生态水利技术创新中心江西南昌330029 江西省鄱阳湖水资源与环境重点实验室江西南昌330029 河海大学水文水资源与水利工程科学国家重点实验室江苏南京210098

萍水河湘东段区域受洪水灾害影响较大,历年损失严重。本文使用MIKE FLOOD构建了萍水河湘东段区域洪水演进一二维耦合模型,结合2019年实测水位过程和调查洪痕等资料验证了模型合理性。根据研究区设防情况,确定了20年、50年和100年一遇3... 详细信息

萍水河湘东段区域受洪水灾害影响较大,历年损失严重。本文使用MIKE FLOOD构建了萍水河湘东段区域洪水演进一二维耦合模型,结合2019年实测水位过程和调查洪痕等资料验证了模型合理性。根据研究区设防情况,确定了20年、50年和100年一遇3种设计洪水计算方案,并分别提取了3种计算方案下的洪水风险特征要素(包括最大淹没水深、最大演进流速和淹没历时等),使用综合风险度法开展了萍水河湘东段区域洪水风险区划研究。结果表明:萍水河湘东段区域洪水风险区划分为极高、高、中和低风险4个等级;其中,中下游无堤防保护区域洪水风险等级为极高或高风险;湘东区县城区域洪水风险等级主要为高风险和中风险,县政府驻地区域属于洪水灾害高风险等级区。本文洪水风险区划成果可为湘东区防洪规划及非工程措施建设提供科学依据。

关键词：洪水风险区划 MIKE FLOOD 综合风险度萍水河