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Characterization of size effect of natural convection in melting process of phase change material in square cavity

Chinese Physics B 2021年第10期30卷 400-409页

作者： shi-hao cao Hui Wang College of Civil Engineering Henan University of TechnologyZhengzhou 450001China School of Civil Engineering and Architecture Hainan UniversityHaikou 570228China

The accelerating effect of natural convection on the melting of phase change material(PCM)has been extensively ***,such an influence is directly dependent on the size and shape of domain in which phase change happens,and how to quantitatively describe such an influence is still *** the other hand,the simulation of natural convection process is considerably difficult,involving complex fluid flow in a region changing with time,and is typically not operable in *** overcome these obstacles,the present study aims to quantitatively investigate the size effect of natural convection in the melting process of PCM paraffin filled in a square latent heat storage system through experiment and simulation,and ultimately a correlation equation to represent its contribution is ***,the paraffin melting experiment is conducted to validate the two-dimensional finite element model based on the enthalpy ***,a comprehensive investigation is performed numerically for various domain *** results show that the melting behavior of paraffin is dominated by the thermal *** the melting time exceeds 50 s,a whirlpoor flow caused by natural convection appears in the upper liquid phase region close to the heating wall,and then its influencing range gradually increases to accelerate the melting of ***,its intensity gradually decreases as the distance between the melting front and the heating wall ***,it is found that the correlation between the total melting time and the domain size approximately exhibits a power *** the domain size is less than 2 mm,the accelerating effect of natural convection becomes very weak and can be ignored in ***,in order to simplify the complex calculation of natural convection,the equivalent thermal conductivity concept is proposed to include the contribution of natural convection to the total melting time,and an empirical correlation is given fo

关键词： phase change material natural convection size effect equivalent thermal conductivity

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Constructing Pr-doped CoOOH catalytic sites for efficient electrooxidation of 5-hydroxymethylfurfural

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Journal of Energy Chemistry 2025年第1期100卷 234-244页

作者： Botao Fan hao Zhang Bang Gu Feng Qiu Qiue cao Wenhao Fang School of Chemical Science and Technology Yunnan University National Center for International Research on Photoelectric and Energy Materials School of Materials and Energy Yunnan University

Electrocatalytic conversion of renewable biomass is emerging as a promising route for sustainable chemical production;hence it urgently calls for developing efficient electrocatalysts with low potentials and high current ***,a Pr-doped Co（OH）2hexagonal sheet （Pr/Co=1/9,in mole） is synthesized by electrodeposition as highly performant catalyst for 5-hydroxymethylfurfural （HMF） oxidation reaction（HMFOR） to produce 2,5-furandicarboxylic acid （FDCA）.This novel and low-cost catalyst possesses a rather low onset potential of 1.05 V （***） and requires only 1.10 V （***） to reach a current density of 10 mA cm-2for HMFOR,significantly outperforming Co（OH）2benchmark (i.e.,210 mV higher to reach10 m A cm-2).The origin of Pr promotion effect as well as the evolution of CoOOH catalytic sites and HMFOR process has been deeply elucidated by physical characterizations,kinetic experiments,in situ electrochemical techniques,and theoretical *** unique Pr-ameliorated CoOOH active centers enable 100%conversion of HMF,99.6%selectivity of FDCA,and 99.7%Faraday efficiency,with a superior cycling durability toward *** can be one of the most outstanding results for Co-based HMFOR catalysts to date in the *** this work can help open up new horizons for constructing novel and efficient Co-based electrocatalysts by the utilization of lanthanide elements.

关键词： Bioconversion

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Ammonia-induced CuO/13X for H_(2)S removal from simulated blast furnace gas at low temperature

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Green Energy & Environment 2025年第1期10卷 139-149页

作者： Erping cao Yuhua Zheng hao Zhang Jianshan Wang Yuran Li Tingyu Zhu Zhan-guo Zhang Guangwen Xu Yanbin Cui State Key Laboratory of Mesoscience and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing100190China State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization PanGang Group Research Institute Co.Ltd.Panzhihua Sichuan617000China Shenyang University of Chemical Technology Shenyang110142China University of Chinese Academy of Sciences Beijing 100049China

Blast furnace gas(BFG)is an important by-product energy for the iron and steel industry and has been widely used for heating or electricity ***,the undesirable contaminants in BFG(especially H_(2)S)generate harmful environmental *** desulfurization of BFG is urgent for integrated steel plants due to the stringent ultra-low emission *** with other desulfurization materials,zeolite-based adsorbents represent a viable option with low costs and long service *** this study,an ammonia-induced CuO modified 13X adsorbent(NH3–CuO/13X)was prepared for H_(2)S removal from simulated BFG at low *** XRD,H_(2)-TPR and TEM analysis proved that smaller CuO particles were formed and the dispersion of Cu on the surface of 13X zeolite was improved via the induction of *** on H_(2)S adsorption performance of the adsorbent was carried out using simulated BFG,and the results showed that NH3–CuO/13X-3 has better breakthrough sulfur capacity,which was more than twice the sulfur capacity of CuO/*** is proposed that the enhanced desulfurization performance of NH3–CuO/13X is attributed to an abundant pore of 13X,and combined action of 13X and *** work provided an effective way to improve the sulfur capacity of zeolite-based adsorbents via impregnation method by ammonia induction.

关键词： Blast furnace gas Desulfurization Ammonia-induced CuO 13X zeolite

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Federated local causal structure learning

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Science China(Information Sciences) 2025年

作者： Kui YU Chen RONG hao WANG Fuyuan cao Jiye LIANG School of Computer and Information Hefei University of Technology School of Computer and Information Technology Shanxi University

Local causal structure learning (LCS) efficiently identifies a set of direct neighbors of a specified variable from observational data. Additionally, it distinguishes direct causes and direct effects of this variable without learning the entire causal structure. While many LCS algorithms have been proposed, they do not consider the data privacy-preserving problem,which has attracted extensive attention from academia and industry. To address this issue, we propose a federated local causal structure learning (FedLCS) algorithm to learn local causal structures in privacy-preserving data in a federated ***, FedLCS introduces a layer-wise federated local skeleton learning algorithm to construct the local skeleton. Based on this skeleton, it introduces a federated local skeleton orientation algorithm and an extension-and-backtracking orientation algorithm to orient the edges. Finally, FedLCS uses a federated local extension-and-backtracking orientation algorithm to orient the remaining edges. Extensive experiments on benchmark, synthetic, and real datasets demonstrate that FedLCS can learn the local causal structure of a given variable in a federated setting.

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Aperiodically semi-intermittent-based fixed-time stabilization and synchronization of delayed discontinuous inertial neural networks

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Science China(Information Sciences) 2025年第1期68卷 238-254页

作者： Guodong ZHANG Jinde cao School of Mathematics and Statistics South-Central Minzu University School of Mathematics Southeast University

This article concentrates on the fixed-time stabilization(FS) and fixed-time synchronization(FTS) of discontinuous inertial neural networks(DINNs) with distributed delays. Using mathematical induction to a new differential equality, a novel fixed-time stability lemma is constructed. Then, by designing an aperiodically semi-intermittent switching control and combining it with the theory of nonsmooth analysis, some novel criteria on the FS and FTS of DINNs are obtained. Unlike the methods used in most existing studies, the FS and FTS results are structured using the newly proposed fixed-time stability lemma and the nonreduced-order approach, resulting in broader practical applications and strengthening the scientific quality of the derived results. Lastly, numerical simulations and applications proffer the effectiveness of the established FS and FTS criteria.

关键词： inertial neural networks fixed-time synchronization semi-intermittent switching control nonreduced-order approach fixed-time stabilization

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Experimental Observing Damage Evolution in Cement Pastes Exposed to External Sulfate Attack by in situ X-ray Computed Tomography

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 164-170页

作者： WU Min cao Kailei XIAO Weirong YU Zetai cao Jierong DING Qingjun LI Jinhui China Railway Construction Corporation Harbour and Channel Engineering Bureau Group Co. LTDZhuhai 519000China Con-struction Headquarters of Zhoushan Liuheng Bridge Phase II Project Zhoushan 316000China China Railway Construction Bridge En-gineering Bureau Group Co. LTDTianjin 300000China State Key Laboratory of Silicate Material for Architecture(Wuhan University of Technology) Wuhan 430070China College of Materials Science and Engineering Wuhan Textile UniversityWuhan 430200China

The paper presents experimental investigation results of crack pattern change in cement pastes caused by external sulfate attack(ESA).To visualize the formation and development of cracks in cement pastes under ESA,an X-ray computed tomography(X-ray CT)was used,i e,the tomography system of Zeiss Xradia 510 *** results indicate that X-CT can monitor the development process and distribution characteristics of the internal cracks of cement pastes under ESA with attack *** addition,the C3A content in the cement significantly affects the damage mode of cement paste specimens during sulfate *** damage of ordinary Portland cement(OPC)pastes subjected to sulfate attack with high C3A content are severe,while the damage of sulfate resistant Portland cement(SRPC)pastes is much smaller than that of OPC ***,a quadratic function describes the correlation between the crack volume fraction and development depth for two cement pastes immermed in sulfate solution.

关键词： concrete external sulfate attack damage evolution situ X-ray computed tomography

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Si-C Foam Porous-Medium Combustion Power-Generation System for Low-Calorific-Value Biomass Syngas

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Journal of Thermal Science 2025年第1期34卷 206-222页

作者： YANG Jianwen CHEN Wei cao Bingwei LIU Xinhui LI Hang College of Mechanical and Aerospace Engineering Jilin University School of Mechanical and Vehicle Engineering Changchun University

Syngas produced from the gasification of organic feedstocks from biomass is one of the clean and sustainable sources of *** advantages of simple access and renewability of biomass energy can meet the energy needs of temporary power *** study presents a biomass power-generation system for vehicular *** biomass and a free-piston Stirling engine generator（FPSEG） as the primary material and prime mover,respectively,biomass energy is converted into electricity by combusting the syngas to heat the *** and key parameter design for biomass gasification and thermoelectric conversion systems within a power generation system were performed.A porous medium area was constructed using Si-C foam ceramics to obtain an energy-conversion experimental *** effects of bed height,porosity,porous-region diameter,and air-intake conditions on the power-generation performance were investigated,and optimisations were performed for the thermoelectric conversion *** rate of increase during FPSEG power generation first increased and then decreased with increasing bed height,peaking at a bed height of 40 *** increasing porous-region diameter accelerated FPSEG power generation,whereas porosity changes in the porous media did not significantly affect the rate of change during FPSEG power *** increasing air intake,the rate of increase during power generation first increased and then *** maximum change rate and the highest thermoelectric conversion efficiency of the power-generation system occurred at 9.5 m3/h and 6.5 m3/h（～45.1%）air intakes,*** the thermal inertia and combustion structure of the thermoelectric conversion system significantly increased the power-generation rate of the system,with 1.8 W/s being observed at a 9.7 m3/h air intake.

关键词： biomass combined heat and power (CHP) gasification porous media combustion power generation

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Anisotropic transport properties and topological Hall effect in the annealed kagome antiferromagnet FeGe

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Science China(Physics,Mechanics & Astronomy) 2025年

作者： Jiajun Ma Chenfei shi Yantao cao Yuwei Zhang Yazhou Li Jiaxing Liao Jialu Wang Wenhe Jiao Hanjie Guo Chenchao Xu shixun cao Jianhui Dai Jin-Ke Bao Yuke Li School of Physics Hangzhou Key Laboratory of Quantum Matters Hangzhou Normal University Department of Physics Materials Genome Institute and International Center for Quantum and Molecular StructuresShanghai University Songshan Lake Materials Laboratory School of Physical Science and Technology Lanzhou University Key Laboratory of Quantum Precision Measurement of Zhejiang Province Department of Applied PhysicsZhejiang University of Technology

Electron correlation often gives birth to various orders in quantum materials. Recently, a strongly correlated kagome antiferromagnet FeGe is discovered to undergo a charge density wave transition inside the A-type antiferromagnetic state, providing an opportunity to explore the interplay between charge order and magnetism. Here, we reported the observation of anisotropic resistivity and Hall effect, along with a topological Hall effect, in the annealed FeGe crystals. As the current flows along the abplane, the temperature dependence of ρabexhibits a distinct resistivity loop related to a first-order transition at Tcdw. The applied magnetic fields do not alter Tcdwbut can induce a spin-flop transition at Hsf. Consequently, a field-induced large topological Hall effect is observed in the canting antiferromagnetic（CAFM） state below Tcant, which is possibly attributed to the non-trivial spin texture during the spin-flop process. Whereas, as current is parallel to c-axis, both the field-induced transitions in ρcand χcdisappear. Instead, the Hall resistivity in the annealed FeGe significantly exhibits a deviation from the linear *** findings provide valuable insight into revealing the interplay among magnetism, charge order and topology in the kagome magnets.

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Melting Evaluation of Phase Change Materials Impregnated into Cascaded Metal Foams with Regionalized Enhancement

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Journal of Thermal Science 2025年第1期34卷 223-241页

作者： WEI Xinyi ZHANG Nan ZHANG Zhaoli cao Xiaoling YUAN Yanping School of Mechanical Engineering Southwest Jiaotong University

Metal foam promotes the heat transfer of phase change materials(PCMs) in the penalty of reducing the energy storage density of the composite *** this work,the effects of constant porosity(0.96,0.94,0.92,or 0.90) and pore density(PPI) of metal foam on heat transfer of composite PCMs are *** rate could be enhanced by employing with low porosity copper ***,aiming to the right bottom phase changing "dead region",a regionalized enhancement strategy of cascaded metal foams is *** dynamic melting performances of all the composite PCMs are comprehensively *** results reveal that the cascaded configuration is beneficial for *** show that the horizontal strategy enhances melting performance:a maximum of 17.98% reduction in total melting time could be reached when the rear part porosity is 90%.The energy storage density rate could be raised by 5.48%.Besides,the vertical strategy performs with a better average temperature uniformity of 0.441 and brings a lower temperature in the heated *** sum up,the regionalized enhancement of copper foam provides better performance in the phase change *** shows significant potential for solar heat storage and thermal protection.

关键词： copper metal foam heat transfer enhancement phase change materials regionalized enhancement

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Positive effect of Mo on mechanical properties of a Ni-42W-10Co-x Mo medium heavy alloy

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China Foundry 2025年

作者： Guo-xin cao Jian-xin Dong Yong-sheng He He Jiang Fang hao Zhi-hua Nie Teng-fei Ma Bao-quan Fu School of Materials Science and Engineering University of Science and Technology Beijing Xi'an Superalloy Technology Co. Ltd. School of Materials Science and Engineering Beijing Institute of Technology Key Laboratory of Air-driven Equipment Technology of Zhejiang Province Quzhou University

In this study,a novel Ni-W-Co-Mo medium heavy alloy (MHA) was designed to improve its mechanical strength via Mo *** the Ni-42W-10Co-xM o alloy series,where x represents the weight percent of Mo and varies between 0,1,2,5,and 10,the microstructure transitions from a dendritic structure to a hypoeutectic structure as the Mo content increases from 0 to 5wt.%.Moreover,as the Mo content increases from 0to 10wt.%,the distribution of theμ-phase shifts from being individually dispersed to forming aggregates,and its volume fraction rises from 0.5%to 7.9%.Notably,theμ-phase evolves into an eutectic microstructure,which helps in minimizing the segregation of *** change is accompanied by a substantial enhancement in mechanical properties;specifically,the compressive yield strength at room temperature increases from 350 MPa to 646 MPa,indicating a significant 85%***,the microhardness increases from 230 HV to 304 *** dynamics simulations further reveal that the strengthening mechanism of Ni-42W-10Co-xM o alloys is Mo-induced solid solution strengthening and precipitation strengthening.

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