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Microstructure and graphitization behavior of diamond/SiC composites fabricated by vacuum vapor reactive infiltration

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Rare Metals 2015年第6期34卷 400-406页

作者： Zhen-liang Yang li-gen wang li-Min wang Xin-Bo He Xuan-Hui Qu Rong-Jun liu Hai-Feng Hu Gripm Advanced Materials Co. Ltd State Key Laboratory of Nonferrous Metals and Processes General Research Institute for Nonferrous Metals School of Materials Science and Engineering University of Science and Technology Beijing College of Aerospace and Materials Engineering National University of Defense Technology

To inhibit the graphitization of diamond under high temperature and low pressure, diamond/SiC composites were firstly fabricated by a rapid gaseous Si vacuum reactive infiltration process. The microstructure and graphitization behavior of diamond in the composites under various infiltration temperatures and holding time were investigated. The thermal conductivity of the resul- tant materials was discussed. The results show that the diamond-to-graphite transition is effectively inhibited at temperature of as high as 1600 ℃ under vacuum, and the substantial graphitization starts at 1700 ℃. The microstructure of those ungraphitized samples is uniform and fully densified. The inhibition mechanisms of graphitization include the isolation of the catalysts from diamond by a series of protective layers, high pressure stress applied on diamond by the reaction-bonded SiC, and the moderate gas-solid reaction. For the graphitized samples, the boundary between diamond and SiC is coarse and loose. The graphitization mechanism is considered to be an initial detachment of the bilayers from the diamond surfaces, and subsequently flattening to form graphite. The ungraphitized samples present higher thermal conductivity of about 410 W.m-1.K-1 due to the fine interfacial structure. For the graphitized samples, the thermal conductivity decreases significantly to 285 W.m-1.K-1 as a result of high interfacial thermal resistance.

关键词： Composite Vapor reactive infiltration Microstructure Graphitization Thermal conductivity

Mechanical properties and microstructure of rolled and electrodeposited thin copper foil

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Rare Metals 2016年第12期35卷 909-914页

作者： Xiang-Qian Yin li-Jun Peng Saif Kayani Lei Cheng Jian-Wei wang Wei Xiao li-gen wang Guo-Jie Huang State Key Laboratory of Nonferrous Metals & Processes General Research Institute for Nonferrous Metals Metal Materials Division Korea Institute of Materials Science

Commercial grade rolled and electrodeposited copper foils from Japan and China were selected, and their mechanical properties and microstructure were investigated. It was observed that there are notable differences in fracture strength, elongation at break and hydrophilicity between rol- led and electrodeposited copper foils. The rolled copper foils have higher tensile strength, lower ductility and larger static contact angle than electrodeposited copper foils. The rolled copper foils contain a [^-fiber texture, and the electrodeposited copper foils have random crystalline orientations. It was also observed that the rolled foils have packed grains, and elec- trodeposited foils have equiaxial grains. The uniform fine grain size and a few substructures of Japanese electrode- posited foils are major reasons for their higher elongation.

关键词： Copper foil Rolling Electrodepositing Texture Substructure

Optimal Planning of Hybrid AC/DC Low-voltage Distribution Networks Considering DC Conversion of Three-phase Four-wire Low-voltage AC Systems

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 141-153页

作者： Bo Zhang Lu Zhang Wei Tang gen li Chen wang the College of Information and Electrical Engineering China Agricultural UniversityBeijing 100083China the Electric Energy Group Department of Engineering TechnologyTechnical University of Denmark(DTU)2750 BallerupDenmark the Power Distribution Technology Center State Grid Beijing Electric Power Research InstituteBeijing 100075China

The increasing integration of distributed household photovoltaics(PVs)and electric vehicles(EVs)may further ag gravate voltage violations and unbalance of low-voltage distribu tion networks(LVDNs).DC distribution networks can increase the accommodation of PVs and EVs and mitigate mutilple pow er quality problems by the flexible power regulation capability of voltage source *** paper proposes schemes to es tablish hybrid AC/DC LVDNs considering the conversion of the existing three-phase four-wire low-voltage AC systems to DC op *** characteristics and DC conversion constraints of typical LVDNs are *** addition,converter configura tions for typical LVDNs are proposed based on the three-phase four-wire characteristics and quantitative analysis of various DC ***,an optimal planning method of hybrid AC/DC LVDNs is proposed,which is modeled as a bi-level programming model considering the annual investments and three-phase *** are conducted to verify the effectiveness of the proposed optimal planning *** ulation results show that the proposed optimal planning method can increase the integration of PVs while simultaneously reduc ing issues related to voltage violation and unbalance.

关键词： Optimal planning low-voltage distribution net work three-phase unbalance DC conversion

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基于场矩阵分解机和CNN的点击率预测模型

计算机系统应用 2024年第1期33卷 87-98页

作者：王志格李汪根夏义春高坤束阳葛英奎安徽师范大学计算机与信息学院芜湖241002

点击率预测是在线广告和推荐系统的基本任务之一.主流模型通常通过对高阶和低阶特征进行特征交互建模来提升性能和泛化能力.然而,许多模型往往仅学习每个特征的固定表示,而忽视了特征在不同上下文中的重要性,并且一些模型结构过于简单.... 详细信息

点击率预测是在线广告和推荐系统的基本任务之一.主流模型通常通过对高阶和低阶特征进行特征交互建模来提升性能和泛化能力.然而,许多模型往往仅学习每个特征的固定表示,而忽视了特征在不同上下文中的重要性,并且一些模型结构过于简单.因此,本文提出了特征细化卷积神经网络融合场矩阵分解机(FRCNN-F)模型,以解决这些问题.首先,在特征细化网络(FRNet)中融合了卷积神经网络的特征生成模块,利用其在局部模式下重新组合生成新特征的优势,提升了重要特征选择能力.其次,设计了场矩阵分解机,使模型能够感知上下文并通过不同场的交互进行显示建模,从而增加了子模型的组合方式.最后,通过在Frappe和MovieLens两个公开数据集上对比实验,实验结果表明,FRCNN-F模型相比基线FRNet在AUC得分分别提升了0.32%和0.40%,交叉熵损失函数Logloss分别降低了1.50%和1.11%.该研究对于实现广告的精准投放和个性化推荐具有实际应用的价值.

关键词：点击率预测特征交互特征细化网络卷积神经网络场矩阵分解机

CO_(2)flooding in shale oil reservoir with radial borehole fracturing for CO_(2)storage and enhanced oil recovery

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Petroleum Science 2024年第1期21卷 519-534页

作者： Jia-Cheng Dai Tian-Yu wang Jin-Tao Weng Kang-Jian Tian li-Ying Zhu gen-Sheng li State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China China National Oil and Gas Exploration and Development Company limited Beijing100034China

This study introduces a novel method integrating CO_(2)flooding with radial borehole fracturing for enhanced oil recovery and CO_(2)underground storage,a solution to the limited vertical stimulation reservoir volume in horizontal well fracturing.A numerical model is established to investigate the production rate,reservoir pressure field,and CO_(2)saturation distribution corresponding to changing time of CO_(2)flooding with radial borehole fracturing.A sensitivity analysis on the influence of CO_(2)injection location,layer spacing,pressure difference,borehole number,and hydraulic fractures on oil production and CO_(2)storage is *** CO_(2)flooding process is divided into four *** in layer spacing will significantly improve oil production rate and gas storage ***,serious gas channeling can occur when the spacing is lower than 20 *** the pressure difference between the producer and injector,the borehole number,the hydraulic fracture height,and the fracture width can also increase the oil production rate and gas storage *** analysis shows that layer spacing and fracture height greatly influence gas storage and oil *** outcomes are expected to provide a theoretical basis for the efficient development of shale oil reservoirs in the vertical direction.

关键词： Shale oil Radial borehole fracturing Embedded discrete fracture model Enhanced oil recovery Carbon storage

Room-temperature Self-healing and Recyclable PDMS Elastomers with Superior Mechanical Properties for Triboelectric Nanogenerators

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Chinese Journal of Polymer Science 2024年第10期42卷 1566-1577,I0014页

作者： Shu-Juan wang Lu wang Hong-Zhe Su Zhi-Cheng Wu Qiao-gen Zhang Wei Fan Xin-li Jing School of Chemistry Joint Innovation Center of Thermal Protection MaterialsXi’an Jiaotong UniversityXi’an710049China School of Electrical Engineering Xi’an Jiaotong UniversityXi’an710049China School of Textile Science and Engineering Xi’an Polytechnic UniversityXi’an710048China

Polydimethylsiloxane(PDMS)is an electron-withdrawing material that is widely used in triboelectric nanogenerators(TENGs).However,PDMS has poor mechanical properties after curing and is easily damaged when subjected to long-term ***,the long-term stable operation of TENGs under mechanical deformation cannot be *** this work,multiple hydrogen bonds and aromatic disulfide bonds were introduced into PDMS *** elastomers exhibited high toughness(a tensile strength of 1.91 MPa and an elongation at break of 340%),good recyclability,and room-temperature self-healing properties(healing efficiency of 96.4%in 24 h).Recyclable sandwich-like triboelectric nanogenerators with excellent electrical output performance(13.5 V)and room-temperature self-healing performance(24 h,98%recovery of self-generating performance)were prepared by utilizing the hydrogen bonding between the PDMS elastomer and *** work reported herein offers theoretical guidance and a compelling strategy for developing high-performance TENG negative friction layers.

关键词： Polydimethylsiloxane Aromatic disulfide bonds Hydrogen bonds Room temperature self-healing Triboelectric nanogenerator

Effect of Al content on modification behavior of non-metallic inclusions in high-strength steel treated with rare earth

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Journal of Iron and Steel Research International 2024年第8期31卷 1886-1899页

作者： Zhan-peng Tie Xue-yuan Jiang Hai-yan Tang ·gen li Yu-hang wang Jia-quan Zhang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Continuous Casting Business Section CISDI Engineering Co.Ltd.Chongqing 401122China Special Steel Institute Central Iron and Steel Research Institute Co.Ltd.Beijing 100081China

The influence of Al content(0.0053,0.0171,and 0.0578 wt.%)on the modification behavior of non-metallic inclusions in 20CrMoVTiB steel treated with rare earth elements was studied through high-temperature experiments and thermodynamic *** results showed that the modification products varied with the Al content in steel under 0.01 wt.%of Ce *** formation sequence of typical rare earth inclusions in steel with the increase in Al content was Ce_(2)O_(3)→CeAlO_(3)→CeAl_(11)O_(18),and the final stable products were highly Al content *** the Al content was 0.0053 wt.%,the stable phase in steel was Ce2O3;while the[Al]reached 0.0171 wt.%,the stable phase became CeA1O_(3).As the A1 content reached 0.0578 wt.%,CeAl_(11)O_(18) became the stable *** a result,increasing the Al content could inhibit the precipitation of Ce_(2)O_(3) inclusions in steel while promote the formation of CeAIO3 and CeAl_(11)O_(18) *** addition,both Ca treatment and Ce treatment could effectively refine the size of inclusions in steel by changing their ***,the feeding amount of Ca wire into molten steel should be appropriately reduced under the condition of adding Ce simultaneously,which is expected to be beneficial for an improved Ce treatment effect.

关键词： Rare earth Al content Steel Inclusion Thermodynamics Ca treatment

Tuning the exciton binding energy of covalent organic frameworks for efficient photocatalysis

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Chinese Chemical Letters 2024年第2期35卷 577-583页

作者： Zhangjie Gu Zhen Shan Yulan wang Jinjian wang Tongtong liu Xiaoming li Zhiyang Yu Jian Su gen Zhang Key Laboratory for Soft Chemistry and Functional Materials of Ministry of Education School of Chemistry and Chemical EngineeringNanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of Photocatalysis on Energy and Environment College of ChemistryFuzhou UniversityFuzhou 350002China MIIT Key Laboratory of Advanced Display Material and Devices School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China Key Laboratory of Preclinical Study for New Drugs of Gansu Province School of Basic Medical SciencesLanzhou UniversityLanzhou 730000China

Owing to the large exciton binding energy(>100 meV)of most organic materials,the process of exciton dissociation into free electrons and holes is seriously hindered,which plays a key role in the photocatalytic *** this study,a series of chalcogen(S,Se)-substituted mesoporous covalent organic frameworks(COFs)have been synthesized for enhanced photocatalytic organic *** measurements indicate that the introduction of semi-metallic Se atom and the enlargement of conjugation degree can not only reduce the exciton binding energy accelerating the charge separation,but also reduce the band gap of *** a result,the COF-NUST-36 with the lowest exciton binding energy(39.5 meV)shows the highest photocatalytic performance for selective oxidation of amines(up to 98%*** 97.5%Sel.).This work provides a feasible method for designing COFs with high photocatalytic activity by adjusting exciton binding energy.

关键词： Covalent organic frameworks Exciton binding energy Atom substitution Extended conjugation Photocatalysis

Interpretation and characterization of rate of penetration intelligent prediction model

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Petroleum Science 2024年第1期21卷 582-596页

作者： Zhi-Jun Pei Xian-Zhi Song Hai-Tao wang Yi-Qi Shi Shou-Ceng Tian gen-Sheng li College of Petroleum Engineering China University of Petroleum(Beijing)Beijing102249China State Key Laboratory of Petroleum Resources and Prospecting Beijing102249China Kunlun Digital Technology Co. Ltd.Beijing102206China

Accurate prediction of the rate of penetration(ROP)is significant for drilling *** the intelligent ROP prediction model based on fully connected neural networks(FNN)outperforms traditional ROP equations and machine learning algorithms,its lack of interpretability undermines its *** study proposes a novel interpretation and characterization method for the FNN ROP prediction model using the Rectified linear Unit(ReLU)activation *** leveraging the derivative of the ReLU function,the FNN function calculation process is transformed into vector *** FNN model is linearly characterized through further simplification,enabling its interpretation and *** proposed method is applied in ROP prediction scenarios using drilling data from three vertical wells in the Tarim *** results demonstrate that the FNN ROP prediction model with ReLU as the activation function performs exceptionally *** relative activation frequency curve of hidden layer neurons aids in analyzing the overfitting of the FNN ROP model and determining drilling data *** the well sections with similar drilling data,averaging the weight parameters enables linear characterization of the FNN ROP prediction model,leading to the establishment of a corresponding linear representation ***,the quantitative analysis of each feature's influence on ROP facilitates the proposal of drilling parameter optimization schemes for the current well *** established linear characterization equation exhibits high precision,strong stability,and adaptability through the application and validation across multiple well sections.

关键词： Fully connected neural network Explainable artificial intelligence Rate of penetration ReLU active function Deep learning Machine learning