检索结果-南通市图书馆

Recent advances in FeCl_(3)-photocatalyzed organic reactions via hydrogen-atom transfer

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

Chinese Chemical Letters 2024年第9期35卷 32-40页

作者： Xiao-Ya yuan cong-cong wang Bing Yu Green Catalysis Center College of ChemistryZhengzhou UniversityZhengzhou 450001China National Engineering Research Center of Low-Carbon Processing and Utilization of Forest Biomass Nanjing Forestry UniversityNanjing 210037China

In recent years,FeCl_(3)-photocatalyzed direct C–H/Si–H bond functionalization reactions have attracted huge *** those transformations,chlorine radical(Cl·)could be generated from FeCl_(3)via a ligandto-metal charge transfer(LMCT)/homolysis process under light *** resulting chlorine radical subsequently acts as a hydrogen atom transfer(HAT)agent to abstract the hydrogen atom of aliphatic C–H,O–H,or Si–H bonds to give the corresponding C/Si/O-centered radicals for various organic *** this review,we summarized the recent advances in the application of FeCl_(3)as a HAT photocatalyst for the C/Si–H functionalization to construct C–C,C–N,C–Si,C–S,C–B,and C-P bonds.

关键词： FeCl_(3) Photocatalysis Ligand-to-metal charge transfer Hydrogen atom transfer Chlorine radical

Numerical investigation of the photo-thermal characteristics of a direct absorption solar collector using Monte Carlo and finite volume methods

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第8期67卷 2436-2448页

作者： ZHU YanLong LI SuNing FAN JianHua Kong weiqiang yuan yuan TAN HePing School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Civil Engineering and Mechanical Engineering Technical University of DenmarkKoppels AlléBuilding 4042800 Kgs.LyngbyDenmark School of Vehicle and Energy Yanshan UniversityQinhuangdao 066004China

In this study, a novel model of photothermal conversion in a direct absorption solar collector based on the Monte Carlo and finite volume methods was built and validated and the temperatures of the novel and traditional solar collectors were compared. The sensitivity of the parameters to the radiative heat loss was investigated. Finally, the radiative heat transfer characteristics were discussed using the radiative exchange factor. The results of this study validated the advantages of the novel solar collector at both the surface and fluid temperatures. Under the conditions used in this study, the maximum temperature difference of the novel solar collector was 30 K, compared with 193 K for the traditional solar collector. Furthermore, the collector was divided into several units along the flow direction. The radiative exchange factor indicated that with an increase in the attenuation coefficient, the percentage of radiation intensity in the total solar radiation absorbed by the corresponding unit ***, it decreased with an increase in the incident angle and scattering albedo. These results provide a reference for addressing the low efficiency and thermal damage caused by traditional solar collectors at high temperatures.

关键词： direct absorption solar collector radiative heat transfer Monte Carlo

Intelligent overheating fault diagnosis for overhead transmission line using semantic segmentation

在线全文

学校读者我要写书评

暂无评论

High Voltage 2024年第2期9卷 309-318页

作者： Xiangyu Yang Youping Tu Zhikang yuan Zhong Zheng Geng Chen cong wang Yan Xu Beijing Key Laboratory of High Voltage and EMC North China Electric Power UniversityBeijingChina College of Electronic and Information Engineering Tongji UniversityShanghaiChina

The strain clamps and leading wires are important components that connect conductors on overhead transmission lines and conduct *** operation,poor contact between these components can cause abnormal overheating,leading to electric failures and threatening power system ***,the use of unmanned aerial vehicles equipped with infrared thermal imagers for strain clamp and leading wire maintenance has become increasingly *** learning-based image recognition shows promising prospects for intelligent fault diagnosis of overheating faults.A pre-treatment method is proposed based on dynamic histogram equalisation to enhance the contrast of infrared *** DeepLab v3+network,loss function,and existing networks with different backbones are *** DeepLab v3+network with ResNet101 and convolutional block attention module added,and the Focal Loss function achieved the highest performance with an average pixel accuracy of 0.614,an average intersection over union(AIoU)of 0.567,an F1 score of 0.644,and a frequency weighted intersection over union of 0.594 on the test *** optimised Atrous rates has increased the AIoU by 12.91%.Moreover,an intelligent diagnosis scheme for evaluating the defect state of the strain clamps and leading wires is proposed and which achieves a diagnostic accuracy of 91.0%.

关键词： union fault diagnosis

Biomass-based production of trimellitic and trimesic acids

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

Green Energy & Environment 2024年第8期9卷 1267-1278页

作者： Lin yuan Yancheng Hu Guangyi Li Fengan Han Aiqin wang Yu cong Tao Zhang Feng wang Ning Li CAS Key Laboratory of Science and Technology on Applied Catalysis Dalian Institute of Chemical PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences 19 A Yuquan RoadShijingshan District School of Chemical Engineering and Technology China University of Mining and Technology State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences

The production of industrial chemicals with renewable biomass feedstock holds potential to aid the world in pursuing a carbon-neutral *** and trimesic acids are important commodity chemicals in industry that are prepared by the oxidation of petroleum-derived *** reduce the dependence on the limited oil source,we develop a potential sustainable alternative towards trimellitic and trimesic acids using biomass-based 2-methyl-2,4-pentandiol （MPD）,acrylate and crotonaldehyde as starting *** process for trimellitic acid includes dehydration/D-A reaction of MPD and acrylate,flow aromatization over Pd/C catalyst,hydrolysis and catalytic aerobic oxidation （60%overall yield）.The challenging regioselectivity issue of D-A reaction is tackled by a matched combination of temperature and deep eutectic solvent ChCl/*** can also participate in the reaction,followed by Pd/C-catalyzed decarbonylation/dehydrogenation and oxidation to provide trimesic acid in 54%overall *** cycle assessment implies that compared to conventional fossil process,our biomass-based routes present a potential in reducing carbon emissions.

关键词： Biomass Trimellitic acid Trimesic acid Deep eutectic solvent Dehydration/D-A reaction

Simultaneously enhancing erosion and compression resistance:designing AlCoCrFeNi high-entropy alloy strengthened Ag-based contacts

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第9期43卷 4476-4492页

作者： Xiao-Yang Xue Zhe wang Hui-Ling Nie Zhao yuan Jun wang Chang-Hu Xu Kai Wen cong-Hao Yu School of Materials Science and Engineering Xi’an Polytechnic University School of Physics Xi’an Jiaotong University Key Laboratory of Pulsed Power Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology

Designing microstructures and unveiling dynamic erosion mechanisms remain important challenges for Ag-based contacts. To simultaneously enhance erosion and compression resistance, an Al Co Cr Fe Ni high-entropy alloy(HEA) is introduced into Ag-based materials to fabricate novel Ag-HEA contacts with island-and skeletonrestricted microstructures. The arc erosion experimental results reveal that the skeleton-restricted HEA microstructure is the key factor in reducing the hill and crater morphologies of the contact surface, effectively delaying material transfer between the movable and stationary contacts. The molten bridge evolution and compressive deformation behavior of Ag-HEA contacts with various microstructures are investigated using molecular dynamics(MD) simulations. MD results indicate that the constraint of Ag atom diffusion in the molten pool and the involvement of HEA atoms in the molten bridge are the primary mechanisms for improving erosion resistance. The skeleton-restricted HEA microstructure reduces the total energy and structural stability of the molten bridge system and promotes its fracture and disintegration. Moreover, the synergistic effect of the twin and Lomerz–Cottrell lock structures can hinder dislocation glide, generating dispersed and small-area stacking faults in the Ag matrix and mitigating the concentration of shear strains. Thus, the skeleton-restricted HEA microstructure contributes positively to compression resistance. This study presents a novel approach to designing Ag-based contacts.

关键词： Arc erosion Electrical contact materials High entropy alloys Microstructures Molecular dynamics

Parameter selection for the hydroconversion of waste polyethylene plastic under mild conditions: A comprehensive evaluation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第8期67卷 2413-2426页

作者： CHENG LeiLei CHEN RuiZhe ZHU weiqiang TIAN ShaoNan GU Jing yuan HaoRan CHEN Yong Guangzhou Institute of Energy Conversion Chinese Academy of SciencesGuangzhou 510640China School of Energy Science and Engineering University of Science and Technology of ChinaHefei 230026China Institute of Process Engineering Chinese Academy of SciencesBeijing 100190China

The hydrogenolysis/hydrocracking of waste polyethylene(PE) has recently been intensively studied, with the general pursuit of low-temperature reaction conditions, increased oil-phase yield, and narrower carbon chain distribution. Before this, we utilized a ball-milled ZSM-22 catalyst loaded with Ru nanoparticles(NPs), which exhibited excellent hydroconversion performance. It deconstructed PE into >80 wt.% oil products under low temperatures and short reaction times. Herein, we investigated the influence of varying temperature/pressure parameters on the degree of specific hydrocracking/internal hydrogenolysis/terminal hydrogenolysis reactions. From the comprehensive energy efficiency perspective, including stirring, reaction, and product separation, as well as taking into account the degree of product isomerization and catalyst lifespan, we analyzed the optimization of parameters. This research abandons the notion that lower temperatures are better and proposes a more comprehensive evaluation framework for low-consumption hydroconversion of PE to produce high-value products.

关键词： plastic upcycling polyethylene hydrocracking hydrogenolysis comprehensive energy efficiency

同方期刊数据库

Coercivity mechanism of high-performance anisotropic heterostructure SmCo5 magnets

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第10期42卷 1882-1888页

作者： yuan Teng Yuqing Li weiqiang Liu Xiaochang Xu Zhanjia wang Jianjun Yang Dongtao Zhang Hongguo Zhang Qingmei Lu Qiong Wu Weixing Xia Ming Yue Faculty of Materials and Manufacturing Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of Technology School of Mechanical and Electrical Engineering Henan Institute of Science and Technology School of Mechanical Engineering Anyang Institute of Technology Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of Sciences

Due to its large magnetocrystalline anisotropy field and high Curie temperature,SmCo-based magnets are irreplaceable in high-temperature applications,The hot-deformed SmCo-based magnets are especially attractive for their excellent corrosion resistance,making them more suitable for harsh ***,it is still challenging for hot-deformed SmCo-based magnets to obtain high magnetization and high coercivity ***,it is necessary to analyze the relationship between its microstructure and magnetic properties and explore its magnetic hardening mechanism to guide the further improvement of magnetic *** this paper,the anisotropic heterostructure SmCo5magnet was prepared by combining large height-reduction and introducing a nano-grained Smrich *** c-axis texture,（BH）m of 16.1 MGOe,and Hciof 9.6 kOe were obtained via the heterostructure with SmCo5micron-grain and Sm-rich nano-scale *** magnetic domain observation and technical magnetization analysis demonstrate that the coe rcivity mechanism is dominated by *** results also show that the smooth and Sm-rich precipitated grain boundary provides weak pinning *** provides a reference for the development of high-pe rformance nanocrystalline SmCo5magnets.

关键词： Coercivity mechanism Heterostructure Hot-deformed SmCo magnet Permanent magnet Rare earths

Robustness of the octupole collectivity in 144Ba within the cranking covariant density functional theory in 3D lattice

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第8期35卷 124-131页

作者： Ze‑Kai Li yuan‑yuan wang Mathematics and Physics Department North China Electric Power UniversityBeijing 102206China Hebei Key Laboratory of Physics and Energy Technology North China Electric Power UniversityBaoding 071000China

The octupole deformation and collectivity in octupole double-magic nucleus 144Ba are investigated using the Cranking covariant density functional theory in a three-dimensional lattice *** reduced B(E3)transition probability is implemented for the first time in semiclassical approximation based on the microscopically calculated electric octupole *** available data,including the I-ωrelation and electric transitional probabilities B(E2)and B(E3)are well ***,it is shown that the ground state of 144Ba exhibits axial octupole and quadrupole deformations that persist up to high spins(I≈24h).

关键词： Octupole collectivity Cranking covariant density functional theory Rotational spectrum Electric transitional probabilities

Transfer matrix method for free and forced vibrations of multi-level functionally graded material stepped beams with different boundary conditions

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6期45卷 983-1000页

作者： Xiaoyang SU Tong HU Wei ZHANG Houjun KANG Yunyue cong Quan yuan School of Civil Engineering and Architecture Guangxi UniversityNanning 530004China Scientific Research Center of Engineering Mechanics Guangxi UniversityNanning 530004China State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures Guangxi UniversityNanning 530004China

Functionally graded materials(FGMs)are a novel class of composite materials that have attracted significant attention in the field of engineering due to their unique mechanical *** study aims to explore the dynamic behaviors of an FGM stepped beam with different boundary conditions based on an efficient solving *** the assumptions of the Euler-Bernoulli beam theory,the governing differential equations of an individual FGM beam are derived with Hamilton’s principle and decoupled via the separation-of-variable ***,the free and forced vibrations of the FGM stepped beam are solved with the transfer matrix method(TMM).Two models,i.e.,a three-level FGM stepped beam and a five-level FGM stepped beam,are considered,and their natural frequencies and mode shapes are *** demonstrate the validity of the method in this paper,the simulation results by ABAQUS are also *** this basis,the detailed parametric analyses on the frequencies and dynamic responses of the three-level FGM stepped beam are carried *** results show the accuracy and efficiency of the TMM.

关键词： transfer matrix method(TMM) free vibration forced vibration functionally graded material(FGM) stepped beam