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Fabricating functionally graded Fe-Cr-Co permanent magnetic alloys via laser powder bed fusion

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Journal of Iron and Steel Research International 2024年第3期31卷 729-737页

作者： ya-zhou He ya-qing Hou Peng shen Hao Zhang Dong Zhou Hang Su Central Iron and Steel Research Institute Co. Ltd.Beijing 100081China Material Digital R&D Center China Iron and Steel Research Institute Group Co.Ltd.Beijing 100081China

Laser powder bed fusion(LPBF)in-situ alloying technology offers the possibility to construct gradient materials with varied structures and *** graded Fe-Cr-Co permanent magnetic alloys were fabricated by LPBF and in-situ alloying mixed powders of Fe,Cr,and Co *** effects of different Fe,Cr and Co contents on the microstructure,magnetic properties and hardness of Fe-Cr-Co alloys prepared by LPBF were *** as-built Fe-Cr-Co alloys present a single body-centered-cubic phase and have a homogeneous distribution of *** mechanical properties and magnetic properties of the compositionally graded sample show a gradient *** the increase in Cr content,the Vickers hardness of the sample increases,and the saturation magnetization of the sample *** optimal magnetic properties in an isotropic state are given as coercivity HcB=21.65 kA/m,remanence Br=0.70 T and energy product(BH)_(max)=5.35 kJ/m^(3),which are comparable to or higher than the reported magnetic properties in an isotropic state prepared by traditional powder *** in-situ alloying technology has the potential to further explore Fe-Cr-Co magnetic materials,such as those consisting of multiple or more constituent elements,and to maximize the compositional flexibility of magnetic materials.

关键词： Fe-Cr-Co alloy Laser powder bed fusion In-situ alloying Functional material Magnetic property

Shape embedding and retrieval in multi-ﬂow deformation

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Computational Visual Media 2024年第3期10卷 439-451页

作者： Baiqiang Leng Jingwei Huang Guanlin shen bin Wang School of Software Tsinghua UniversityBeijingChina Huawei Technologies ShenzhenChina

We propose a unified 3D ﬂow frameworkfor joint learning of shape embedding and deformationfor different categories. Our goal is to recovershapes from imperfect point clouds by fitting thebest shape template in a shape repository afterdeformation. Accordingly, we learn a shape embeddingfor template retrieval and a ﬂow-based network forrobust deformation. We note that the deformationﬂow can be quite different for different shapecategories. Therefore, we introduce a novel multi-hubmodule to learn multiple modes of deformation toincorporate such variation, providing a network whichcan handle a wide range of objects from differentcategories. The shape embedding is designed to retrievethe best-fit template as the nearest neighbor in a latentspace. We replace the standard fully connected layerwith a tiny structure in the embedding that significantlyreduces network complexity and further improvesdeformation quality. Experiments show the superiorityof our method to existing state-of-the-art methods viaqualitative and quantitative comparisons. Finally, ourmethod provides efficient and flexible deformation thatcan further be used for novel shape design.

关键词： deformation shape retrieval embedding reconstruction

Numerical study on the effective thermal conductivity and thermal tortuosity of porous media with different morphologies

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Science China(Technological Sciences) 2024年第6期67卷 1685-1694页

作者： DU shen LI Dong LI Meng-Jie HE ya-Ling Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China

Effective thermal conductivity and thermal tortuosity are crucial parameters for evaluating the effectiveness of heat conduction within porous *** direct pore-scale numerical simulation method is applied to investigate the heat conduction processes inside porous structures with different *** thermal conduction performances of idealized porous structures are directly compared with real foams across a wide range of *** foam structures are reconstructed using X-ray computed tomography and image processing techniques,while Kelvin and Weaire-Phelan structures are generated through periodic unit cell *** detailed temperature fields inside the porous structures are determined by solving the heat conduction equation at the pore *** results present that the equivalent thermal conductivity of Kelvin and Weaire-Phelan structures is similar to and greater than that of the real foam structure with the same strut *** thermal tortuosity of real foam structure is relatively larger and the heat conduction path becomes straighter by adopting the anisotropic *** thermal tortuosity of the fluid channels for Kelvin,Weaire-Phelan,and real foam structures is close to *** thermal conductivity of porous structures with heat transfer fluid increases as the thermal conductivity ratio of fluid to solid becomes larger.A small porosity of porous media leads to a larger equivalent thermal conductivity due to the dominant contribution of porous skeleton in the heat conduction *** derived from parallel and series models,as well as the Maxwell-Eucken models,provide decent predictions of effective thermal conductivity,with an average error of less than 8%in the entire range of thermal conductivity ratio.

关键词： volumetric solar receiver porous morphology direct pore-scale simulation equivalent thermal conductivity thermal tortuosity empirical correlation

Toughening ultrastrong low-density steel by textured δ-ferrite lamellas

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Defence Technology（防务技术） 2024年第2期32卷 405-411页

作者： bin Hu Guosen Zhu Guohui shen Zheng Wang Qinghua Wen Xiao shen Haiwen Luo School of Metallurgical and Ecological Engineering University of Science and Technology BeijingXue Yuan Rd.30Beijing 100083China Shougang Research Institute of Technology Yangzhuang Street 69Beijing 100043China Steel Institute RWTH Aachen UniversityIntzestraße 152072AachenGermany

By both the Charpy V-notched impact and the projectile tests, we here investigated the dynamic fracture behavior of a recently developed ultrastrong lightweight steel comprising a hierarchical martensitic matrix, dispersed ultra-fine-retained austenite grains and oriented δ-ferrite lamellas, the latter being due to high Al and Si contents employed for low-density design. This steel shows a superior combination of specific ultimate tensile strength and impact toughness to other ultrastrong steels and has successfully arrested a real steel-cored bullet shot. These are attributed to the densely textured δ-ferrite lamellas that can deflect the propagating cracks until they are trapped and enclosed besides austenite-to-martensite transformation crack closure, leading to more energy consumed before failure. These results suggest a new pathway for toughening ultrastrong lightweight steels.

关键词： Ultrastrong and light steel d-Ferrite lamellas Crack propagation Toughness

Recent progress in the research on magnesium and magnesium alloy foils:A short review

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 842-854页

作者： Qiuyan shen Yongxing Ba Peng Zhang Jiangfeng Song bin Jiang Fusheng Pan National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China National Key Laboratory of Advanced Casting Technologies Chongqing UniversityChongqing 400044China

Magnesium and magnesium alloy foils have great potential for application in battery anodes,electromagnetic shielding,optics and acoustics,and biology because of their excellent specific damping,internal dissipation coefficients,magnetic and electrical conductivities,as well as high theoretical specific ***,magnesium alloys exhibit poor deformation ability due to their hexagonal close-packed crystal *** magnesium and magnesium alloy foils with thicknesses of less than 0.1 mm is difficult because of surface oxidation and grain growth at high temperatures or severe anisotropy after cold rolling that leads to *** methods have been applied to prepare magnesium alloy *** include warm rolling,cold rolling,accumulative roll bonding,electric plastic rolling,and on-line heating *** of magnesium and magnesium alloy foils during preparation,such as edge cracks and breakage,are important factors for ***,the current status of the research on magnesium and magnesium alloy foils is summarized from the aspects of foil preparation,defect control,performance characterization,and application *** advantages and disadvantages of different preparation methods and defect(edge cracks and breakage)mechanisms in the preparation of foils are identified.

关键词： magnesium alloy foil rolling defect performance application

Observer-Based Adaptive Robust Precision Motion Control of a Multi-Joint Hydraulic Manipulator

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1213-1226页

作者： Zheng Chen Shizhao Zhou Chong shen Litong Lyu Junhui Zhang bin yao State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027 Ocean College Zhejiang UniversityZhoushan 316021China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050000 State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China School of Mechanical Engineering Purdue UniversityWest LafayetteIN 47907 USA

Hydraulic manipulators are usually applied in heavy-load and harsh operation ***,when faced with a complex operation,the traditional proportional-integral-derivative(PID)control may not meet requirements for high control ***-based full-state-feedback control is an effective alternative,but the states of a hydraulic manipulator are not always available and reliable in practical applications,particularly the joint angular velocity *** that it is not suitable to obtain the velocity signal directly from differentiating of position measurement,the low-pass filtering is commonly used,but it will definitely restrict the closed-loop bandwidth of the whole *** avoid this problem and realize better control performance,this paper proposes a novel observerbased adaptive robust controller(obARC)for a multi-joint hydraulic manipulator subjected to both parametric uncertainties and the lack of accurate velocity ***,a nonlinear adaptive observer is first designed to handle the lack of velocity measurement with the consideration of parametric ***,the adaptive robust control is developed to compensate for the dynamic uncertainties,and the close-loop system robust stability is theoretically proved under the observation and control ***,comparative experiments are carried out to show that the designed controller can achieve a performance improvement over the traditional methods,specifically yielding better control accuracy owing to the closed-loop bandwidth breakthrough,which is limited by low-pass filtering in fullstate-feedback control.

关键词： handle Observer filtering

Cross-diffusion induced Turing instability of Hopf bifurcating periodic solutions in the reaction-diffusion enzyme reaction model

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International Journal of Biomathematics 2024年第4期17卷 133-150页

作者： Haicheng Liu Wenshuo Yuan bin Ge Jihong shen College of Mathematical Sciences Harbin Engineering University Harbin 150001 HeilongjiangP.R.China

Aiming at the spatial pattern phenomenon in biochemical reactions,an enzyme-reaction Sporns-Seelig model with cross-diffusion is chosen as study *** the central manifold theory,normal form method,local Hopf bifurcation theorem and perturbation theory,we study Turing instability of the spatially homogeneous Hopf bifurcation periodic *** last,the theoretical results are verified by numerical simulations.

关键词： Sporns-Seelig model diffusion Hopf bifurcation periodic solutions Turing instability

Decoding the Puzzle of Late Ediacaran Glaciation(s)

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Journal of Earth Science 2024年第3期35卷 1049-1052页

作者： bin Wen yanting Lin Fuyun shen Junyuan Zhou School of Earth Sciences China University of GeosciencesWuhan 430074China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430078China

INTRODUCTION In the Earth’s history,the Late Ediacaran to Early Cambrian period witnessed a series of profound changes in both Earth’s interior and surficial systems which may have made this planet more habitable for the first radiation of early animals(known as the global occurrence of Ediacaran biota;Xiao and Narbonne,2020).Among those changes,the Late Ediacaran glaciation,soon followed and accompanied by the early complex life of Ediacaran biota,attracted much attention of scientists and may have provided a good opportunity to investigate the interactions between the Earth’s surficial environment and the biosphere(e.g.,Xu et al.,2024;Zhang et al.,2023;Hoffman et al.,2017).To achieve this goal,the nature of the glaciation itself needs to be understood *** now,32 or more Ediacaran glacial deposits have been documented on almost all the existing continents(Niu et al.,2024;Wang et al.,2023a,b,c),showing a similar distribution pattern to the two Cryogenian(Sturtian and Marinoan)Snowball Earth glaciations if plotted in one single paleogeographic map(Figure 1;Niu et al.,2024;Li et al.,2013).But further compared to the Cryogenian Snowball Earth glaciations,the Late Ediacaran glaciation has some fundamentally different characteristics:(1)as shown in Figure 1,most glacial deposits are not stratigraphically overlain by the typical cap carbonate while it usually happened in the aftermath of a Snowball Earth glaciation and represented an abrupt climatic switch from extreme icehouse(global freezing)to greenhouse(global warming)condition(Hoffman et al.,2017).

关键词： Earth glacial Cambrian

Uncertainty and sensitivity analysis of in-vessel phenomena under severe accident mitigation strategy based on ISAA-SAUP program

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Nuclear Science and Techniques 2024年第1期35卷 108-123页

作者： Hao yang Ji-shen Li Zhi-Ran Zhang bin Zhang Jian-Qiang Shan School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The phenomenology involved in severe accidents in nuclear reactors is highly ***,integrated analysis programs used for severe accident analysis heavily rely on custom empirical parameters,which introduce considerable ***,in recent years,the field of severe accidents has shifted its focus toward applying uncertainty analysis methods to quantify uncertainty in safety assessment programs,known as“best estimate plus uncertainty(BEPU).”This approach aids in enhancing our comprehension of these programs and their further development and *** study concentrates on a third-generation pressurized water reactor equipped with advanced active and passive mitigation *** an Integrated Severe Accident Analysis Program(ISAA),numerical modeling and uncertainty analysis were conducted on severe accidents resulting from large break loss of coolant *** uncertainty parameters of the ISAA program were meticulously *** Wilks'formula,the developed uncertainty program code,SAUP,was employed to carry out Latin hypercube sampling,while ISAA was employed to execute batch *** analysis was then conducted on two figures of merit,namely hydrogen generation and the release of fission products within the pressure *** calculations revealed that hydrogen production and the fraction of fission product released exhibited a normal distribution,ranging from 182.784 to 330.664 kg and from 15.6 to 84.3%,*** ratio of hydrogen production to reactor thermal power fell within the range of 0.0578–0.105.A sensitivity analysis was performed for uncertain input parameters,revealing significant correlations between the failure temperature of the cladding oxide layer,maximum melt flow rate,size of the particulate debris,and porosity of the debris with both hydrogen generation and the release of fission products.

关键词： Gen-III PWR Severe accident mitigation Wilks’formula Hydrogen Fission products Uncertainty and sensitivity analysis