检索结果-南通市图书馆

Chinese Journal of Chemical Engineering 2024年第5期69卷 1-12页

作者： Zhekun chen Weitong Pan Longfei Tang Xueli chen Fuchen Wang Engineering Research Center of Resource Utilization of Carbon-containing Waste with Carbon Neutrality Ministry of EducationEast China University of Science and TechnologyShanghai 200237China Key Laboratory of Pressure Systems and Safety Ministry of EducationEast China University of Science and TechnologyShanghai 200237China

Ensuring the consistency of electrode structure in proton-exchange-membrane fuel cells is highly desired yet challenging because of wide-existing and unguided cracks in the microporous layer(MPL). The first thing is to evaluate the homogeneity of MPL with cracks quantitatively. This paper proposes the homogeneity index of a full-scale MPL with an area of 50 cm~2, which is yet to be reported in the literature to our knowledge. Besides, the effects of the carbon material and surfactant on the ink and resulting MPL structure have been studied. The ink with a high network development degree produces an MPL with low crack density, but the ink with high PDI produces an MPL with low crack homogeneity. The polarity of the surfactant and the non-polarity of polytetrafluoroethylene(PTFE) are not mutually soluble,resulting in the heterogeneous PTFE distribution. The findings of this study provide guidelines for MPL fabrication.

关键词： Proton-exchange-membrane fuel cell Microporous layer Crack density Crack homogeneity Polytetrafluoroethylene distribution Surfactant

Dynamics and vibration reduction performance of asymmetric tristable nonlinear energy sink

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 389-406页

作者： Hongyan chen Youcheng ZENG Hu DING Siukai LAI Liqun chen School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina

With its complex nonlinear dynamic behavior,the tristable system has shown excellent performance in areas such as energy harvesting and vibration suppression,and has attracted a lot of *** this paper,an asymmetric tristable design is proposed to improve the vibration suppression efficiency of nonlinear energy sinks(NESs)for the first *** proposed asymmetric tristable NES(ATNES)is composed of a pair of oblique springs and a vertical ***,the three stable states,symmetric and asymmetric,can be achieved by the adjustment of the distance and stiffness asymmetry of the oblique *** governing equations of a linear oscillator(LO)coupled with the ATNES are *** approximate analytical solution to the coupled system is obtained by the harmonic balance method(HBM)and verified *** vibration suppression efficiency of three types of ATNES is *** results show that the asymmetric design can improve the efficiency of vibration reduction through comparing the chaotic motion of the NES oscillator between asymmetric steady *** addition,compared with the symmetrical tristable NES(TNES),the ATNES can effectively control smaller structural *** other words,the ATNES can effectively solve the threshold problem of TNES failure to weak ***,this paper reveals the vibration reduction mechanism of the ATNES,and provides a pathway to expand the effective excitation amplitude range of the NES.

关键词： asymmetric nonlinear energy sink(NES) tristable vibration control po-tential barrier

福州城市扩张对地表温度影响及其空间分异分析

在线全文

学校读者我要写书评

暂无评论

海南师范大学学报（自然科学版） 2023年第3期36卷 301-311页

作者：陈梦迪张友水福建师范大学地理科学学院/碳中和未来技术学院福建福州350117 福建师范大学地理研究所福建福州350117

基于福州城区两时相Landsat影像,根据城市发展程度差异将研究区划分为Zone 1、Zone 2、Zone 3三个环形区域,在反演地表温度和获取不透水面覆盖度信息的基础上,计算各区域各级不透水面覆盖度的热分布指数和热效应贡献度指数,分析2004—2... 详细信息

基于福州城区两时相Landsat影像,根据城市发展程度差异将研究区划分为Zone 1、Zone 2、Zone 3三个环形区域,在反演地表温度和获取不透水面覆盖度信息的基础上,计算各区域各级不透水面覆盖度的热分布指数和热效应贡献度指数,分析2004—2021年福州市不同发展程度区不透水面覆盖度与地表温度之间的定量关系,并运用地理探测器分析植被覆盖度、不透水面覆盖度和海拔高度对地表温度(Land Surface Temperature,LST)空间异质性的影响。结果表明:2004—2021年,Zone 1不透水面扩张较少,Zone 2和Zone 3不透水面扩张明显,增加最明显的为Zone 3内不透水面覆盖度大于60%的区域;不透水面覆盖度大于60%的区域对城市高温面积贡献最大,不透水面覆盖度为80%~100%时热效应贡献度最大;2004年影响地表温度的主导因子为植被覆盖度,2021年Zone 1中不透水面覆盖度为影响地表温度的主导因子,其余区域中海拔高度为影响地表温度的主导因子;福州市地表温度空间分异受多因子共同影响且两因子交互q值均高于单因子q值。研究结果可为城市规划和缓解城市热岛效应提供参考。

关键词：城市热环境不透水面覆盖度地理探测器热效应贡献混合像元分解空间分异

Progress and prospects of Mg-based amorphous alloys in azo dye wastewater treatment

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

Journal of Magnesium and Alloys 2024年第3期12卷 873-889页

作者： Yanan chen Fengchun chen Liang Li chen Su Bo Song Hongju Zhang Shengfeng Guo Fusheng Pan School of Materials and Energy Southwest UniversityChongqing 400715China Analytical and Testing Center Southwest UniversityChongqing 400715China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

Mg-based amorphous alloys exhibit efficient catalytic performance and excellent biocompatibility with a promising application probability,specifically in the field of azo dye wastewater ***,the problems like difficulty in preparation and poor cycling stability need to be *** present,Mg-based amorphous alloys applied in wastewater degradation are available in powder and *** amorphous alloy powder fabricated by ball milling has a high specific surface area,and its reactivity is thousands of times better than that of gas atomized alloy *** the development is limited due to the high energy consumption,difficult and costly process of powder *** single roller melt-spinning method is a new manufacturing process of amorphous alloy *** to amorphous powder,the specific surface area of amorphous ribbon is relatively lower,therefore,it is necessary to carry out surface modification to enhance *** is a way that can form a pore structure on the surface of the amorphous alloys,increasing the specific surface area and providing more reactive sites,which all contribute to the catalytic *** the optimal conditions for Mg-based amorphous alloys in wastewater degradation by adjusting amorphous alloy composition,choosing suitable method to preparation and surface modification,reducing cost,expanding the pH range will advance the steps to put Mg-based amorphous alloys in industrial environments into practice.

关键词： Mg-based amorphous alloys Azo dyes Dealloying Surface modification Wastewater degradation.

A two-step multi-frequency receiver function inversion method for shallow crustal S-wave velocity structure and its application across the basin-mountain range belts in Northeast China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第3期67卷 687-703页

作者： Ruihao YANG Xu WANG Ling chen Mingye FENG Qifu chen State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

A shallow crustal velocity structure(above 10 km depth) is essential for understanding the crustal structures and deformation and assessing the exploration prospect of natural resources, and also provides priori information for imaging deeper crustal and mantle structure. Passive-source seismic methods are cost-effective and advantageous for regional-scale imaging of shallow crustal structures compared to active-source methods. Among these passive methods, techniques utilizing receiver function waveforms and/or body-wave amplitude ratios have recently gained prominence due to their relatively high spatial resolution. However, in basin regions, reverberations caused by near-surface unconsolidated sedimentary layers often introduce strong non-uniqueness and uncertainty, limiting the applicability of such methods. To address these challenges, we propose a two-step inversion method that uses multi-frequency P-RF waveforms and P-RF horizontal-to-vertical amplitude ratios. Synthetic tests indicate that our two-step inversion method can mitigate the non-uniqueness of the inversion and enhance the stability of the results. Applying this method to teleseismic data from a linear seismic array across the sedimentary basins in Northeast China, we obtain a high-resolution image of the shallow crustal S-wave velocity structure along the array. Our results reveal significant differences between the basins and mountains. The identification of low-velocity anomalies(<2.8 km s^(-1)) at depths less than 1.0 km beneath the Erlian Basin and less than 2.5 km beneath the Songliao Basin suggests the existence of sedimentary layers. Moreover, the high-velocity anomalies(~3.4–3.8 km s^(-1)) occurring at depths greater than 7 km in the Songliao Basin may reflect mafic intrusions emplaced during the Early Cretaceous. Velocity anomaly distribution in our imaging result is consistent with the location of the major faults, uplifts, and sedimentary depressions, as well as active-source seismic res

关键词： Receiver function Frequency dependence Two-step inversion Shallow crustal velocity structures Unconsolidated sedimentary basins

The growth ofβphase in Mg-Gd-Y-Ni alloy by experimental and first-principles study

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第2期12卷 506-515页

作者： Yiqiang Hao Lei Zhou Zhiqing chen Zhixian Zhao Bin chen School of Materials Science and Engineering Shanghai Jiao Tong University800 Dongchuan RoadShanghai200240China

The paper reports on the atomic investigation aboutβphase in Mg_(96)Gd_(2)Y_(1)Ni_(1) alloy by using the first-principles study and the high-angle annular dark-field scanning transmission electron microscope(HAADF-STEM)corrected by atomic *** using HAADF-STEM,the rectangularβphases were observed in the underage and peak aging stages in Mg_(96)Gd_(2)Y_(1)Ni_(1) ***βphase could be precipitated from the previously precipitatedβphase,and theβphase grew in steps when it was precipitated.A special transition structure of three atomic layer thicknesses was first observed at the edge of theβphase and the structure of this interface is probably as theβ/Mg_(1) interface for the analysis of thermodynamic characterization and electronic ***β'phase and theβ_(H) structure were precipitated only at the edge of the length directions of theβ***β'phase continues to grow into aβphase directly without the formation ofβ_(1) phase,resulting in an increase in the length of theβphase,which is discovered for the first time.

关键词： HAADF-STEM First-principles study Mg-Gd-Y-Ni alloy βphase Growth Interface

Grouping Decision Algorithm for Dynamic Terminals in Random Access Networks

在线全文

学校读者我要写书评

暂无评论

Journal of Communications and Information Networks 2024年第2期9卷 176-183页

作者： Hongliang Sun Tongfei chen Chuangye Zhao Mengxin chen College of Information and Control Engineering Jilin Institute of Chemical TechnologyJilin 132022China

This paper proposes a grouping decision algorithm for random access networks with the carrier sense multiple access (CSMA) mechanism, which can balance the traffic load and solve the hidden terminal issue. Considering the arrival characteristics of terminals and quality of service (QoS) requirements, the traffic load is evaluated based on the effective bandwidth theory. Additionally, a probability matrix of hidden terminals is constructed to take into account the dynamic nature of hidden terminal relations. In the grouping process, an income function is established with a view to the benefits of decreasing the probability of hidden terminal collisions and load balancing. Then, we introduce the grey wolf optimization (GWO) algorithm to implement the grouping decision. Simulation results demonstrate that the grouping algorithm can effectively alleviate the performance degradation and facilitate the management of network resources.

关键词： random access network hidden terminal collision probability effective bandwidth traffic load grey wolf optimization

An overview of potential cardioprotective benefits of xanthophylls in atherosclerosis:an evidence-based review

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

Food Science and Human Wellness 2024年第4期13卷 1739-1755页

作者： Yuting Su Feng chen Jiehua chen Mingfu Wang Shenzhen Key Laboratory of Marine Microbiome Engineering Institute for Advanced StudyShenzhen UniversityShenzhen 518060China Institution for Innovative Development of Food Industry Shenzhen UniversityShenzhen 518060China College of Civil and Transportation Engineering Shenzhen UniversityShenzhen 518060China Shenzhen Key Laboratory of Food Nutrition and Health Shenzhen UniversityShenzhen 518060China

Atherosclerosis,as the most prevalent form of cardiovascular disease,is characterized by oxidized lowdensity lipoprotein(ox-LDL)accumulation in the vascular wall,increased inflammation of the large arteries,dysfunction of the endothelial cells(ECs)and vascular smooth muscle cells(VSMCs),which may eventually lead to the formation of ***,one of the main groups of carotenoids,have been proposed as preventive agents or adjunct therapies to prevent and slow the progression of atherosclerosis due to their cardioprotective ***,the underlying preventive mechanism of action of xanthophylls on the pathogenesis of atherosclerosis remains unclear,and clinical evidence of the effect of xanthophylls on atherosclerosis have not yet been summarized and critically *** this regard,we conducted a comprehensive literature search in four scientific databases(Pub Med,Google Scholar,Science Direct and Web of Science)and carefully analyzed the existing evidence to provide meaningful insights on the association between xanthophylls and atherosclerosis from various *** on the evidence from in vitro and in vivo studies,we explored several potential mechanisms,including antioxidant effect,anti-inflammatory effect,regulation of lipid metabolism,and modulation of ECs and VSMCs dysfunction,and we found that a clear picture of regulatory pathways of xanthophylls on atherosclerosis prevention and treatment is still *** addition,epidemiological studies suggested the possible relationship among high dietary intake of xanthophylls,high plasma/serum xanthophylls and a reduced risk of *** evidence from interventional studies investigating the effect of xanthophylls on atherosclerosis is very sparse,whilst indirect clinical evidence was only limited to astaxanthin and ***,well-designed long-term randomized controlled trials(RCTs)are highly recommended for future studies to investigate the effective dose of different

关键词： Atherosclerosis Xanthophylls Antioxidant Anti-inflammation Lipid metabolism

Robust fixed-time flight controller for a dual-system convertible UAV in the cruise mode

在线全文

学校读者我要写书评

暂无评论

DEFENCE TECHNOLOGY 2024年第9期39卷 53-66页

作者： chen, Lulu Liu, Zhenbao Dang, Qingqing Zhao, Wen chen, Wenyu Northwestern Polytech Univ Sch Civil Aviat Xian 710072 Peoples R China Northwestern Polytech Univ Shenzhen Res Inst Shenzhen 518057 Peoples R China Air Force Engn Univ Air & Missile Def Coll Xian 710051 Peoples R China

This paper investigates the attitude tracking control problem for the cruise mode of a dual-system convertible unmanned aerial vehicle (UAV) in the presence of parameter uncertainties, unmodeled uncertainties and wind disturbances. First, a fixed-time disturbance observer (FXDO) based on the bi-limit homogeneity theory is designed to estimate the lumped disturbance of the convertible UAV model. Then, a fixed-time integral sliding mode control (FXISMC) is combined with the FXDO to achieve strong robustness and chattering reduction. Bi-limit homogeneity theory and Lyapunov theory are applied to provide detailed proof of the fixed-time stability. Finally, numerical simulation experimental results verify the robustness of the proposed algorithm to model parameter uncertainties and wind disturbances. In addition, the proposed algorithm is deployed in a open-source UAV autopilot and its effectiveness is further demonstrated by hardware-in-the-loop experimental results. (c) 2024 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Convertible UAV Flight control Disturbance observer Fixed-time control QUADROTOR UAV TRACKING CONTROL OBSERVER DESIGN DISTURBANCE VEHICLE SCHEME

Acoustic carrier signal transmission technology and its potential for in-site monitoring of sliding electrical contact used in gas-insulated switchgear/gas-insulated transmission line

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

High Voltage 2024年第2期9卷 287-295页

作者： chen chen Yutong Zhang Huijun Zhao Zongren Peng Qingyu Wang Xi'an Jiaotong University Xi'anChina

A wireless signal transmission technology based on acoustic carrier is proposed,which overcomes the limitation of electromagnetic signal shielding and shows great potential for in-site monitoring of sliding electrical contact used in gas-insulated switchgear(GIS)/gasinsulated transmission line(GIL).Here,the state parameter of the sliding electrical contact is modulated onto the frequency domain of an ultrasound *** a mechanical wave,the ultrasonic wave is immune to electromagnetic shielding,so that it could carry the sensing signal to penetrate the metal shielding layer and transmit to the external terminals of GIS/*** principle and signal modulation process of the acoustic carrier based transmission system have been demonstrated in *** simulation and experiment have been conducted to analyse the system characteristics as well as optimise the system *** a proof-of-concept application,the in situ and on-line monitoring of the thermal rise of a slide electrical contact both in a current loading equivalent model and a prototype of GIS is *** results fit well with the physical process,and show a good measurement accuracy of 0.6%and tem-perature sensitivity of 400 Hz/℃.

关键词： electrical potential Acoustic