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Modeling Method of C/C-ZrC Composites and Prediction of Equivalent Thermal Conductivity Tensor Based on Asymptotic Homogenization

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工程与科学中的计算机建模(英文) 2024年第1期138卷 391-410页

作者： Junpeng Lyu Hai Mei Liping Zu Lisheng Liu Liangliang Chu department of Mechanics and Engineering Structure Wuhan University of TechnologyWuhan430070China Hubei Key Laboratory of Theory and application of advanced Materials Mechanics Wuhan University of TechnologyWuhan430070China

This article proposes a modeling method for C/C-ZrC composite *** to the superposition of Gaussian random field,the original gray model is obtained,and the threshold segmentation method is used to generate the C-ZrC inclusion ***,the fiber structure is added to construct the microstructure of the three-phase plain weave *** reconstructed inclusions can meet the randomness of the shape and have a uniform *** an algorithm based on asymptotic homogenization and finite element method,the equivalent thermal conductivity prediction of the microstructure finite element model was carried out,and the influence of component volume fraction on material thermal properties was *** sensitivity of model parameters was studied,including the size,mesh sensitivity,Gaussian complexity,and correlation length of the RVE model,and the optimal calculation model was *** results indicate that the volume fraction of the inclusion phase has a significant impact on the equivalent thermal conductivity of the *** the volume fraction of carbon fiber and ZrC increases,the equivalent thermal conductivity tensor gradually *** model can be used to explore the impact of materialmicrostructure on the results,and numerical simulations have studied the relationship between structure and performance,providing the possibility of designing microstructure based on performance.

关键词： 3D reconstruction randomheterogeneous media microstructure asymptotic homogenization effective properties

Updated Lagrangian Particle Hydrodynamics (ULPH)Modeling of Natural Convection Problems

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 151-169页

作者： Junsong Xiong Zhen Wang Shaofan Li Xin Lai Lisheng Liu Xiang Liu Hubei Key Laboratory of Theory and application of advanced Materials Mechanics Wuhan University of TechnologyWuhan430070China department of Engineering Structure and Mechanics Wuhan University of TechnologyWuhan430070China department of Civil and Environmental Engineering The University of CaliforniaBerkeleyCA 94720USA

Natural convection is a heat transfer mechanism driven by temperature or density differences,leading to fluid motion without external *** occurs in various natural and engineering phenomena,influencing heat transfer,climate,and fluid mixing in industrial *** work aims to use the Updated Lagrangian Particle Hydrodynamics(ULPH)theory to address natural convection *** Navier-Stokes equation is discretized using second-order nonlocal differential operators,allowing a direct solution of the Laplace operator for temperature in the energy *** numerical simulations,including cases such as natural convection in square cavities and two concentric cylinders,were conducted to validate the reliability of the *** results demonstrate that the proposed model exhibits excellent accuracy and performance,providing a promising and effective numerical approach for natural convection problems.

关键词： Updated Lagrangian particle hydrodynamics(ULPH) natural convection meshless methods higher order Laplacian model

Transition-metal free trifluoromethylimination of alkenes enabled by direct activation of N-unprotected ketimines

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Chinese Chemical Letters 2024年第9期35卷 155-159页

作者： Boqiang Wang Yongzhuo Xu Jiajia Wang Muyang Yang Guo-Jun Deng Wen Shao Key Laboratory for Green Organic Synthesis and application of Hunan Province Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationCollege of ChemistryXiangtan UniversityXiangtan 411105China department School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang 453007China

A highly site-selective intermolecular trifluoromethylimination of activated and unactivated olefins was reported under transition-metal-and photosensitizer-free *** newly developed strategy provides straightforward and efficient access to diverse value-added vicinal trifluoromethyl amines without resorting to the pre-functionalized *** experiments demonstrate that the approach proceeded through CF_(3)and iminyl two-radicals process,which were generated directly from commercially available benzophenone imine in a novel electron-donor mode via a SET process activated by the bifunctional hypervalent iodine *** synthetic potential of the protocols was further showcased via the condensation/amination sequential cascade,and transformations to accessβ-CF_(3)primary amines.

关键词： Transition-metal free Alkenes difunctionalization Amination Trifluoromethylation Single-electron transfer

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Spark Plasma Sintering of Boron Carbide Using Ti_(3)SiC_(2) as a Sintering Additive

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 645-650页

作者： Hülya Biçer Mustafa Tuncer Hasan Göçmez Iurii Bogomol Valerii Kolesnichenko Andrey Ragulya Kutahya Dumlupinar University School of EngineeringDepartment of Metallurgical and Materials EngineeringKütahya 43100Tur-key Boron Based advanced Ceramics application and Research Center Kütahya Dumlupınar UniversityKütahya 43100Turkey advanced Technologies Center(İLTEM) Kütahya Dumlupınar UniversityKütahya 43000Turkey department of High-Temperature Ma-terials and Powder Metallurgy National Technical University of Ukraine“Igor Sikorsky Kyiv Polytechnic Institute”Kyiv 03056Ukraine Frantsevich Institute for Problems of Materials Science National Academy of Sciences of UkraineKyiv 03056Ukraine

Boron carbide has unique properties for wide application possibilities;however,poor sinterability limits its *** approach to overcome this limitation is the addition of secondary phases into boron *** carbide based composite ceramics are produced by the direct addition of secondary phases into the structure or via reactive sintering using a sintering *** present study investigated the effect of Ti_(3)SiC_(2) addition to boron carbide by reactive spark plasma sintering in the range of 1700-1900℃.Ti_(3)SiC_(2) phase decomposed at high temperatures and reacted with B4C to form secondary phases of TiB2 and *** results demonstrated that the increase of Ti_(3)SiC_(2) addition(up to 15 vol%)effectively promoted the densification of B4C and yielded higher ***,as the amount of Ti_(3)SiC_(2) increased further,the formation of microstructural inhomogeneity and agglomeration of secondary phases caused a decrease in hardness.

关键词： reactive sintering SPS boron carbide MAX phase

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supporting IrO_(x) nanosheets on hollow TiO_(2) for highly efficient acidic water splitting

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Nano Research 2024年第8期17卷 6903-6909页

作者： Ge Yu Ruilong Li Yanmin Hu Xingen Lin Ze Lin Dongyang Wu Gongming Wang Xun Hong Center of advanced Nanocatalysis(CAN) Department of Applied ChemistryUniversity of Science and Technology of ChinaHefei 230026China

The efficiency of proton exchange membrane water electrolysis(PEM-WE)for hydrogen production is heavily dependent on the noble metal iridium-based ***,the scarcity of iridium limits the large-scale application of *** address this issue,it is promising to select an appropriate support because it not only enhances the utilization efficiency of noble metals but also improves mass transport under high ***,we supported amorphous IrO_(x) nanosheets onto the hollow TiO_(2) sphere(denoted as IrO_(x)),which demonstrated excellent performance in acidic electrolytic water ***,the annealed IrO_(x)catalyst at 150℃in air exhibited a mass activity of 1347.5 A·gIr^(−1),which is much higher than that of commercial IrO_(2) of 12.33 A·gIr^(−1) at the overpotential of 300 mV for oxygen evolution reaction(OER).Meanwhile,the annealed IrO_(x) exhibited good stability for 600 h operating at 10 mA·cm^(−2).Moreover,when using IrO_(x) and annealed IrO_(x) catalysts for water splitting,a cell voltage as low as 1.485 V can be achieved at 10 mA·cm^(−2).The cell can continuously operate for 200 h with negligible degradation of performance.

关键词： oxygen evolution reaction hydrogen evolution reaction amorphous IrO_(x) hollow TiO_(2) proton exchange membrane water electrolysis

MOF-derived Cu embedded into N-doped mesoporous carbon as a robust support of PdAu nanocatalysts for ethanol electrooxidation

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Rare Metals 2024年第3期43卷 1083-1094页

作者： Yu-Fu Huang Peng Wu Jun-Ping Tang Jian Yang Jing Li Shuai Chen Xue-Ling Zhao ChengChen Bin-Wei Zhang Yan-Yun Ma Wei-Heng Shi Dong-Hai Lin Shi-Gang Sun School of Energy and Materials Shanghai Engineering Research Center of Advanced Thermal Functional MaterialsShanghai Key Laboratory of Engineering Materials Application and EvaluationShanghai Polytechnic UniversityShanghai201209China State Key Laboratory of Physical Chemistry of Solid Surfaces Department of ChemistryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen361005China School of Chemistry and Chemical Engineering Chongqing UniversityChongqing401331China Center of advanced Energy Technology and Electrochemistry Institute of Advanced Interdisciplinary StudiesChongqing UniversityChongqing400044China Institute of Functional Nano&Soft Materials(FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials&DevicesSoochow UniversitySuzhou215123China department of Materials Science and Engineering Drexel UniversityPhiladelphiaPA19104USA

Metal-organic frameworks(MOFs)h ave attracted widespread attention due to their large surface area and porous *** designing the nanostructures of MOFs to promote their application in ethanol electrooxidation is still a ***,a novel Cu-NCNs(Cu-nitrogen-doped carbon nanotubes)support was synthesized by pyrolysis of melamine(MEL)and Cu-ZIF-8 together,and then,Pd-Au nanoalloys were loaded by sodium borohydride reduction method to prepare PdAu@Cu-NCNs *** generating mesoporous carbon with high specific surface area and favorable electron and mass transport can be used as a potential excellent carrier for PdAu *** addition,the balance of catalyst composition and surface structure was tuned by controlling the content of Pd and ***,the best-performed Pd_(2)Au_(2)@Cu-NCN-1000-2(where 1000 means the carrier calcination temperature,and 2 means the calcination constant temperature time)catalyst exhibits better long-term stability and electrochemical activity for ethanol oxidation in alkaline media(4.80 A·mg^(-1)),which is 5.05 times higher than that of commercial Pd/C(0.95 A·mg^(-1)).Therefore,this work is beneficial to further promoting the application of MOFs in direct ethanol fuel cells(DEFCs)and can be used as inspiration for the design of more efficient catalyst support structures.

关键词： Metal-organic frameworks(MOFs) N-doped Mesoporous carbon PdAu Ethanol electrooxidation

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Flow-based queue management for fairness control in high-bandwidth network

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Science China(Information Sciences) 2016年第6期59卷 261-263页

作者： Wonjun CHOI Ramneek SEKHON Woojin SEOK department of Science and Technology Information Science Korea University of Science & Technology department of advanced kreonet application support Korea Institute of Science and Technology Information

Dear editor,With the development of information equipment and growth of broadband network,the progress of Internet has changed from the network with modem speed in the past to the *** essential problem in the use of the network in a variety of fields is to use the network resource efficiently distributing the limited bandwidth[1].If congestion occurs in high-bandwidth network,slow rate flow and fast rate flow will experience

关键词： Flow-based queue management for fairness control in high-bandwidth network high

Flexible mica films coated by magnetron sputtered insulating layers for high-temperature capacitive energy storage

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SusMat 2024年第5期4卷 154-162页

作者： Chao Yin Tiandong Zhang Changhai Zhang Yue Zhang Chang Kyu Jeong Geon-Tae Hwang Qingguo Chi Key Laboratory of Engineering Dielectrics and its application Ministry of EducationHarbin University of Science and TechnologyHarbinChina School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbinChina Division of advanced Materials Engineering Jeonbuk National UniversityJeonjuSouth Korea department of Materials Science and Engineering Pukyong National UniversityBusanSouth Korea

High-temperature energy storage performance of dielectric capacitors is cru-cial for the next generation of power electronic ***,conduction losses rise sharply at elevated temperature,limiting the application of energy storage ***,the mica films magnetron sputtered by different insulating layers are specifically investigated,which exhibit the excellent high-temperature energy storage *** experimental results revealed that the PbZrO3/Al2O3/PbZrO3(PZO/AO/PZO)interface insulating layers can effec-tively reduce the high-temperature leakage current and conduction loss of the composite ***,the ultrahigh energy storage density(Wrec)and charge‒discharge efficiency(η)can be achieved simultaneously in the flexi-ble mica-based composite ***,PZO/AO/PZO/mica/PZO/AO/PZO(PAPMPAP)films possess excellent Wrec of 27.5 J/cm3 andηof 87.8%at 200◦C,which are significantly better than currently reported high-temperature capaci-tive energy storage dielectric *** with outstanding power density and electrical cycling stability,the flexible films in this work have great appli-cation potential in high-temperature energy storage ***,the magnetron sputtering technology can deposit large-area nanoscale insulating layers on the surface of capacitor films,which can provide technical support for the industrial production of capacitors.

关键词： energy storage high temperature insulating layer magnetron sputtering mica

De novo Synthesis of Chiral 3,4-Dihydroquinazolines via One-Pot Enantioselective Ugi-Azide/Cyclization Sequences

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Chinese Journal of Chemistry 2024年第18期42卷 2140-2146页

作者： Zu-Kui Xie Jun-Jun Ding Yi-Ming Ou Jun-Xiu Shi Meng-Lan Shen Chuan-Zhi Yao Hua-Jie Jiang Jie Yu department of Applied Chemistry Anhui Province Engineering Laboratory for Green Pesticide Development and Applicationand Anhui Province Key Laboratory of Crop Integrated Pest ManagementAnhui Agricultural UniversityHefeiAnhui 230036China

Background and Originality Content,3,4-Dihydroquinazoline frameworks have frequently been encountered in natural products and bioactive *** the past decades,these key structures prompted the development of creative pharmaceuticals owing to their prominent biological properties,including trypanothione reductase(TryR)inhibitor,Hepatitis B virus(HBV)inhibitive activities,anticancer activities,etc.(Scheme 1A).[1]Notably,the chirality of the C4 atom is crucial for drug *** example,the DPC-083 is a potent reverse transcriptase inhibitor for the treatment of HIV infection but the undesired enantiomers exhibit virtually no activity.[ia]Therefore,developing synthetic methods for innovative chiral 4-substituted 3,4-dihydroquinazolines is significant and essential for drug discovery.

关键词： Anionic stereogenic-at-cobalt(ll)complex De novo synthesis post-Ugi transformation One-pot sequence Asymmetric synthesis Multicomponentreactions