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Numerical simulation of melt flow and temperature field during DC casting 2024 aluminium alloy under different casting conditions

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China Foundry 2024年第4期21卷 387-396页

作者： Jin-chuan Wang yu-bo zuo Qing-feng Zhu Jing Li Rui Wang Xu-dong Liu Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Engineering Research Center of Advanced Materials Preparing Technology Ministry of EducationShenyang 110819China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Casting speed,casting temperature and secondary cooling water flow rate are the main process parameters affecting the DC casting *** parameters significantly influence the flow and temperature fields during casting,which are crucial for the quality of the ingot and can determine the success or failure of the casting *** simulation,with the advantages of low cost,rapid execution,and visualized results,is an important method to study and optimize the DC casting *** the present work,a simulation model of DC casting 2024 aluminum alloy was established,and the reliability of the model was ***,the influence of casting parameters on flow field and temperature field was studied in detail by numerical simulation *** show that with the increase of casting speed,the melt flow becomes faster,the depths of slurry zone and mushy zone increase,and the variation of slurry zone depth is greater than that of mushy *** an increase in casting temperature,the melt flow rate increases,the depth of the slurry zone becomes shallower,and the depth of the mushy zone experiences only minor *** simulation results further indicate that the increase of the flow rate of the secondary cooling water slightly reduces the depths of both slurry and mushy zone.

关键词： aluminium DC casting flow field temperature field numerical simulation

An Improved UNet Lightweight Network for Semantic Segmentation of Weed Images in Corn Fields

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Computers, Materials & Continua 2024年第6期79卷 4413-4431页

作者： yu zuo Wenwen Li School of Information and Control Engineering Jilin Institute of Chemical TechnologyJilin132022China School of Mechanical and Control Engineering Baicheng Normal UniversityBaicheng137000China

In cornfields,factors such as the similarity between corn seedlings and weeds and the blurring of plant edge details pose challenges to corn and weed *** addition,remote areas such as farmland are usually constrained by limited computational resources and limited collected ***,it becomes necessary to lighten the model to better adapt to complex cornfield scene,and make full use of the limited data *** this paper,we propose an improved image segmentation algorithm based on ***,the inverted residual structure is introduced into the contraction path to reduce the number of parameters in the training process and improve the feature extraction ability;secondly,the pyramid pooling module is introduced to enhance the network’s ability of acquiring contextual information as well as the ability of dealing with the small target loss problem;and lastly,Finally,to further enhance the segmentation capability of the model,the squeeze and excitation mechanism is introduced in the expansion *** used images of corn seedlings collected in the field and publicly available corn weed datasets to evaluate the improved *** improved model has a total parameter of 3.79 M and miou can achieve 87.9%.The fps on a single 3050 ti video card is about *** experimental results show that the network proposed in this paper can quickly segment corn weeds in a cornfield scenario with good segmentation accuracy.

关键词： Semantic segmentation deep learning UNet pyramid pooling module

Predicting the evolution of electrochemical trepanning for inner blisks with a chamfer structure at blade tip

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CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 560-576页

作者： Jiao, Erhao Zhu, dong Wang, Penghui zuo, Hang Chen, Liyong Nanjing Univ Aeronaut & Astronaut Coll Mech & Elect Engn Nanjing 210016 Peoples R China

Electrochemical trepanning (ECTr) is an effective electrochemical machining (ECM) technique that can be used to manufacture the integral components of aero-engine compressors. This study focused on the dynamic evolution of ECTr for production of inner blisks (bladed disks) with a special chamfer structure at blade tip. Due to the existence of chamfer, the ECTr process of inner blades is in a non-equilibrium state during the early stages, and the physical field changes in the machining gap are complex, making it difficult to predict the forming process. In this paper, a dynamic evolution model (DEM) of inner blade ECTr with a special chamfer at blade tip structure is proposed, and an ECTr multi-physical fields simulation study was carried out. The evolution of the chamfer at blade tip was analyzed and data related to chamfer were predicted based on the dependence of anode boundary properties with machining time and feed rate. In addition, the distributions of current density, electrolyte flow rate, bubble volume fraction, temperature rise, and electrolyte conductivity in the machining area at different times were obtained by combining them with the multi-physical fields simulation results. Subsequently, a series of ECTr experiments were conducted, in which, as the feed rate increased, the surface quality and machining accuracy of the inner blades were improved. Compared with the simulation results, the error in machining accuracy of the chamfer profile is controlled within +/- 2%, and the machining accuracy of the blade full profile was controlled within +/- 0.2 mm, indicating that the model proposed in this study was effective in predicting the evolution of inner blades ECTr with chamfer structures at blade tip. (c) 2024 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Chamfer structure Inner blisk Electrochemical trepanning (ECTr) Dynamic evolution model Forming prediction Multiphysics Machining quality MATERIAL REMOVAL PROCESS CONVEX STRUCTURE SIMULATION MANUFACTURE PART

Simulation Analysis of DC Fault Interruption Characteristics of Superconducting Electric Aircraft Propulsion

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1834-1842页

作者： Muhammad Junaid Xiaolong yu Shuzhi Cao Wenqing yu dongsheng zuo Jianhua Wang School of Electrical Engineering Nanhu CampusChina University of Mining and TechnologyXuzhouJiangsu 221116China Shanghai Dianji University Shanghai 201306China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’anShaanxi 710049China

Environmental issues associated with the aviation industry are getting more attention as air traffic *** standards are imposed for fuel consumption and pollution emissions for next-generation *** electrical propulsion aircraft(SEPA)have been seen as an efficient way to achieve this ***-temperature superconducting(HTS)devices are extensively used in the power system to supply enormous *** is distributed to the different loads via a DC distribution ***,it will generate an inrush current over ten times higher than the rated current in short-circuit state,which is very harmful to the ***,it is essential to adopt an appropriate protection *** paper discusses one protection scheme that combines DC vacuum circuit breakers(DC VCB)and resistive superconducting current limiters(RSFCL)for superconducting aircraft *** problems of cost and loss,the auxiliary capacitor is pre-charged by system voltage,and mechanical elements extinguish the ***,combined with RSFCL,the interrupting environment is fully *** limits fault current,and then the VCB breaks this limited current based on creating an artificial current zero(ACZ).The prospective rated power is 8MW,rated voltage and current are 4 kV and 1 kA,*** this paper,we discuss and simulate switching devices that protect *** interrupting performance of the circuit breaker is analysed in the DC short-circuit fault that occurs on the transmission ***,the residual energy consumption of different situations is calculated.A comparison is made between using RSFCL with metal oxide varistor(MOV)and just using *** scheme with RSFCL shows a significant advantage in energy consumption.

关键词： Artificial current zero DC circuit breakers metal oxide varistor RSFCL superconducting electrical propulsion aircraft

Optimizing the sulfur-resistance and activity of perovskite oxygen carrier for chemical looping dry reforming of methane

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Journal of Energy Chemistry 2024年第9期96卷 259-271页

作者： yuelun Li dong Tian Lei jiang Huicong zuo LiNan Huang Mingyi Chen Jianchun zuo Hua Wang Kongzhai Li Engineering Research Center of Metallurgical Energy Conservation and Emission Reduction Ministry of EducationKunming University of Science and TechnologyKunming 650093YunnanChina Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunming 650093YunnanChina State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Kunming University of Science and TechnologyKunming 650093YunnanChina

Perovskite oxides has been attracted much attention as high-performance oxygen carriers for chemical looping reforming of methane,but they are easily inactivated by the presence of trace H_(2)***,we propose to modulate both the activity and resistance to sulfur poisoning by dual substitution of Mo and Ni ions with the Fe-sites of LaFeO_(3)*** is found that partial substitution of Ni for Fe substantially improves the activity of LaFeO_(3)perovskite,while Ni particles prefer to grow and react with H_(2)S during the long-term successive redox process,resulting in the deactivation of oxygen *** the presence of Mo in LaNi_(0.05)Fe_(0.95)O_(3−σ)perovskite,H_(2)S preferentially reacts with Mo to generate MoS_(2),and then the CO_(2)oxidation can regenerate Mo via removing *** addition,Mo can inhibit the accumulation and growth of Ni,which helps to improve the redox stability of oxygen *** LaNi_(0.05)Mo_(0.07)Fe_(0.88)O_(3−σ)oxygen carrier exhibits stable and excellent performance,with the CH_(4)conversion higher than 90%during the 50 redox cycles in the presence of 50 ppm H_(2)S at 800℃.This work highlights a synergistic effect in the perovskite oxides induced by dual substitution of different cations for the development of high-performance oxygen carriers with excellent sulfur tolerance.

关键词： Perovskite oxygen carriers Chemical looping reforming Sulfur-resistance Dual substitution Syngas

Selective adsorption of tetracycline by β-CD-immobilized sodium alginate aerogel coupled with ultrafiltration for reclaimed water

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Chinese Journal of Chemical Engineering 2024年第4期68卷 27-34页

作者： Xi Quan Jun Zhang Linlin Yin Wei zuo yu Tian State Key Laboratory of Urban Water Resource and Environment(SKLUWRE) School of EnvironmentHarbin Institute of TechnologyHarbin 150090China

In this work,a novel composite material based on β-cyclodextrin-immobilized sodium alginate aerogel(β-CD/NaAlg) was developed utilizing cross-linker of epichlorohydrin and applied as an adsorbent to remove tetracycline antibiotics from reclaimed wastewater.A series of characterizations were utilized to confirm the successful synthesis of the adsorbent and this β-CD/NaAlg presented a three-dimensional network at the nanoscale or *** optimal conditions(pH=4,t=8 h,β-CD:NaAlg=9,adsorbent dosage = 1.5 g·L-1),the maximum removal rate of β-CD/NaAlg to tetracycline was 70%.The adsorption behavior of tetracycline on β-CD/NaAlg conformed to the Freundlich isotherm model(R2=0.9977) and the pseudo-second-order kinetic model(R^(2)=0.9993).Moreover,the adsorbent still removed 55.3% of tetracycline after five ***,the adsorbent was integrated with ultrafiltration to adsorb tetracycline antibiotics from simulated reclaimed wastewater,and the removal rate of tetracycline reached 78.9% within 2 *** existence of Cr(Ⅵ) had a negligible impact on tetracycline removal,while the presence of humic acid exhibited a promoting *** possible adsorption mechanisms were also elucidated through X-ray photoelectron spectroscopy and density functional theory *** summary,β-CD/NaAlg represents an environmentally friendly,efficient,and sustainable adsorbent for removing tetracycline antibiotics from reclaimed water.

关键词： b-CD/NaAlg aerogel Covalent grafting Tetracycline antibiotics Ultrafiltration Selective adsorption Reclaimed water

Unraveling magnetic properties and martensitic transformation in Mn-rich Ni-Mn-Sn alloys:first-principles calculations and experiments

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Rare Metals 2024年第4期43卷 1769-1785页

作者： yu Zhang Jing Bai Ke-Liang Guo Jia-Xin Xu Jiang-Long Gu Nicola Morley Qui-Zhi Gao yu-dong Zhang Claude Esling Xiang Zhao Liang zuo Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang110819China Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province School of Resources and MaterialsNortheastern University at QinhuangdaoQinhuangdao066004China Department of Material Science and Engineering University of SheffieldSheffieldS13JDUK State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao066004China Laboratoire d’Étude des Microstructures Et de Mécanique des Matériaux University of Lorraine57045MetzFrance

We have investigated the phase stability,magnetic properties,and martensitic transformation thermodynamics/kinetics of the Ni_(24-x)Mn_(18+x+y)Sn_(6-y)(x,y=0,1,2)system by combining the first-principles calculations and *** calculation results show that the optimized lattice parameters are consistent with the experimental ***,we obtain the relation equation for the austenite formation energy(E_(form-A))and Mn content(X_(Mn)):E_(form-A)=507.358X_(Mn)-274.126,as well as for the six-layer modulated(6M)martensite formation energy(E_(form-6M))and Ni content(X_(Ni)):E_(form-6M)=-728.484X_(Ni)+*** ternary phase diagram of the total magnetic moment was *** excess Mn will reduce the total magnetic moment of 6M(Mag6M)and non-modulated(NM)(MagNM)martensites,with the following equations relating the total magnetic moment and Mn content:Mag_(6M)=-15.905X_(Mn)+7.902and Mag_(NM)=-14.781X_(Mn)+7.411,while the effect on austenite is *** variation of total magnetic moment is mainly dominated by the Mn atomic magnetic *** 3d electrons of Mn_(Sn)(Mn at Sn sublattice)play an important role in magnetic properties from the perspective of the electronic density of *** on the thermodynamics of martensitic transformation,the alloys will likely undergo austenite?6M?NM transformation *** the thermodynamic and kinetic results,the martensitic transformation temperature decreases with x increasing and increases with y *** results are expected to provide reference for predicting the phase stability and magnetic properties of NiMn-Sn alloys.

关键词： Ni-Mn-Sn First-principles calculations Martensitic transformation Magnetic property Kinetics

Amplification effect of intra-seasonal variability of soil moisture on heat extremes over Eurasia

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Advances in Climate Change Research 2024年第1期15卷 1-8页

作者： Yi-Nuo WANG Zhi-Yan zuo Liang QIAO Kai-Wen ZHANG Mei-yu CHANG dong XIAO Zou-Xing LIN Huan WANG Department of Atmospheric and Oceanic Sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China CMA-FDU Joint Laboratory of Marine Meteorology Shanghai 200438China Key Laboratory of Cites Mitigation and Adaptation to Climate Change in Shanghai China Meteorological AdministrationShanghai 200030China Collaborative Innovation Centeron Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 211800China Shanghai Frontiers Science Center of Atmosphere-Ocean Interaction Shanghai 200123China College of Geography and Resources Science Sichuan Normal UniversityChengdu 610101China National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary Shanghai 202183China Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing 100081China

Drying soil has been conducive to a high frequency of extreme high-temperature events over many regions worldwide in recent ***,changes in the intraseasonal variability of soil moisture can also influence the likelihood of extremely high *** previous investigators have examined the association between extremely high temperatures and large-scale atmospheric circulation variability,the role of land-atmosphere coupling dominated by soil moisture variability in extremely high temperatures,particularly over the Eurasian continent,is not well *** this study,on the basis of the Land Surface,Snow,and Soil Moisture Model Intercomparison Project,we found that land-atmosphere feedback amplified the variability of soil moisture in most regions of Eurasia during summer from 1980 to *** amplification of soil moisture variability is closely correlated with more intensive intraseasonal variability of surface air temperature and more frequent occurrences of extreme high-temperature events,particularly in Europe,Siberia,Northeast Asia,and the Indochina *** correlation implies that increasing the intraseasonal variability of soil moisture results in a high likelihood of heat extremes during summer in most parts of Eurasia except Asian desert *** the intraseasonal timescale,the land-atmosphere coupling increases the variability of surface sensible heat flux and net long-wave radiation heating the atmosphere by intensifying the soil moisture variability,thus amplifying the variability of surface air temperature and enhancing the extreme high-temperature *** finding demonstrates the importance of changes in intraseasonal soil moisture variability for the increasing likelihood of heat extremes in summer.

关键词： Soil moisture Intraseasonal variability Land-atmosphere coupling Heat extremes

Impact wear properties of dissimilar joints between bainitic frogs and pearlite rails

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Journal of Iron and Steel Research International 2024年第1期31卷 275-287页

作者： Pin-yong Zeng Chun-guang zuo Xiao-yu Zhang Wei Li Tribology Research Institute Southwest Jiaotong UniversityChengdu610031SichuanChina

The impact wear behavior and damage mechanism of dissimilar welded joints between U26Mn frog and U75 V rail before and after normalizing treatment were studied by cyclic impact *** experiment indicated that the impact wear volume of the joints increased with the increasing number of impact *** main wear mechanisms include pitting wear,mild fatigue wear,delamination wear,and fatigue wear,and plastic deformation was the primary impact wear *** them,fatigue wear had the greatest influence on wear volume,while other wear mechanisms had limited *** impact wear resistance of the base material was better than that of the heat-affected *** treatment was beneficial to improving the impact wear resistance of welded joints owing to its effect to promote pearlite recovery,grain refinement,and uniform distribution of *** martensite generated in the rail welded joints aggravated the impact wear damage to the materials,which should be avoided.

关键词： Dissimilar welded joint Impact wear Bainitic steel Damage mechanism Wear rate