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Modelling the formation and dissolution behavior of alumina agglomerate in the cryolite

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Particuology 2024年第3期86卷 211-222页

作者： Jiaqi Wang Mao Li Benjun cheng Hesong Li School of Energy Science and Engineering Central South UniversityChangsha410083China

The presence of alumina agglomerates seriously affects the current efficiency of the aluminum electrolysis *** the dynamic dissolution process of agglomerates is essential to improve the current efficiency of aluminum electrolysis.A mathematical model is proposed to describe the different phenomena from the formation until complete dissolution of *** permeation and solidification processes of cryolite,a semi-analytical mathematical model is developed to formulate the formation,melting and dissolution processes of agglomerates,and the time duration for each stage is *** and heat mass transfer of agglomerates are explored based on the packing theory and mechanism of heat mass transfer in wet porous *** approach is applied to investigate the main factors affecting the dissolution stages and porosity of *** results show that the superheat has a great influence on the formation and melting stage,the diameter of agglomerates can reach 14.93 mm for 200 particles *** density decreases with the increase of agglomerated particle number,which varies in the range of 2.27-2.28 g/cm^(3).The average dissolution rate of agglomerates is about 1.83×10^(-5)-2.95×10^(-5) kg/s within the range of alumina concentration in this study.

关键词： Mathematical model Alumina agglomerate Porous media Packing theory Heatand mass transfer

Integrated spatial-temporal random speckle spectrometer with high resolution in the C-band

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Photonics Research 2024年第7期12卷 1556-1563页

作者： SHIBO XU JIAHUI ZHANG JUNWEI cheng JIANJI DONG Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Optics Valley Laboratory Wuhan 430074China

The increasing demand for diverse portable high-precision spectral analysis applications has driven the rapid development of spectrometer miniaturization. However, the resolutions of existing miniaturized spectrometers mostly remain at the nanometer level, posing a challenge for further enhancement towards achieving picometerlevel precision. Here, we propose an integrated reconstructive spectrometer that utilizes Mach–Zehnder interferometers and a tunable diffraction network. Through random tuning in the time domain and disordered diffraction in the space domain, the random speckle patterns closely related to wavelength information are obtained to construct the transmission matrix. Experimentally, we achieve a high resolution of 100 pm and precisely reconstruct multiple narrowband and broadband spectra. Moreover, the proposed spectrometer features a simple structure, strong portability, and fast sampling speed, which has great potential in the practical application of high-precision portable spectral analysis.

关键词： speckle random resolution

Vision-based docking system for an aromatic-hydrocarbon-inspired reconfigurable robot

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Science China(Technological Sciences) 2024年第6期67卷 1798-1816页

作者： XING FangYi XU cheng LIU JinGuo XUE ZhiHui State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang110016China School of Automation and Electrical Engineering Shenyang Ligong UniversityShenyang110158China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of SciencesShenyang110169China University of Chinese Academy of Sciences Beijing100049China

Aromatic hydrocarbons generally refer to compounds containing benzene *** types of isomers can be formed by replacing hydrogen atoms on the benzene *** this paper,an aromatic-hydrocarbon-inspired modular robot(AHIMR)is *** robot can be reassembled into different configurations suitable for various task requirements.A vision-based docking system is designed for the *** system primarily consists of two stages:a remote guidance stage and a precise docking *** the remote guidance stage,an object module is identified using an illumination adaptive target recognition algorithm,and then the active module moves to the docking area through communication with *** the precise docking stage,the active module calculates the relative pose with the object module using a perspective-n-point method and dynamically adjusts its posture to *** this process,a Kalman filter is used to reduce target occlusion and jitter *** addition,the docking system feasibility is verified via several simulation *** module docking accuracy is controlled within 0.01 m,which meets the reconfiguration task requirements of the *** the AHIMR submodule docking experiment,the active module accurately moves to the expected position with a docking success rate of 95%.

关键词： modular robot reconfiguration aromatic hydrocarbon autonomous docking visual identification

Compound Product of Hypermatrices

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Journal of Systems Science & Complexity 2024年第1期37卷 169-183页

作者： cheng Daizhan MENG Min ZHANG Xiao JI Zhengping Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China Department of Control Science and Engineering School of Electronics and Information EngineeringTongji UniversityShanghai 201210China National Center for Mathematics and Interdisciplinary Sciences Chinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100149China.

The semi-tensor product(STP)of matrices is generalized to multidimensional arrays,called the compound product of *** product is first defined for three-dimensional hypermatrices with compatible orders and then extended to general *** different types of hyperdeterminants are introduced and certain properties are *** Lie groups and Lie algebras corresponding to the hypermatrix products are ***,these results are applied to dynamical systems.

关键词： Compound semi-tensor product hyperdeterminants hypereigenvalues and hypereigenvectors hypergeneral linear groups hypermatrices.

Evolution of inner wall wrinkle defects in the sinking zone of a thick-walled steel tube during radial forging

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Advances in Manufacturing 2024年第2期12卷 396-408页

作者： Yu-Zhao Yang cheng Xu Li-Xia Fan School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094People’s Republic of China

An axial wrinkle defect was observed in the inner wall of the sinking zone of a thick-wall steel tube processed by cold radial *** can evolve into *** present study focuses on the evolution of wrinkles and the effects of process parameters on them using a three-dimensional radial forging process finite element model,radial forging experiments,and surface morphology *** results indicated that the vertical section angle of the hammer die and the size of the tube blank significantly affect the evolution of *** height-to-width ratioλwas introduced to describe the morphology of *** had an approximately linear relationship with the radius reduction in the sinking *** was a linear correlation between the growth slope ofλand the axial to circumferential strain ratio|εr/εθ|,which can predict theλunder few process *** the 30SiMn2MoVA steel,at the junction of the forging and sinking zones,the threshold ofλof the wrinkle that can evolve into a fissure is approximately 1.123.

关键词： Radial forging Inner wall Wrinkle defects Evolution Sinking zone

Effect of boundary conditions on shakedown analysis of heterogeneous materials

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 39-68页

作者： Xiuchen GONG Yinghao NIE Gengdong cheng Kai LI State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentInternational Research Center for Computational MechanicsDepartment of Engineering MechanicsDalian University of TechnologyDalian 116023Liaoning ProvinceChina

The determination of the ultimate load-bearing capacity of structures made of elastoplastic heterogeneous materials under varying loads is of great importance for engineering analysis and design. Therefore, it is necessary to accurately predict the shakedown domains of these materials. The static shakedown theorem, also known as Melan's theorem, is a fundamental method used to predict the shakedown domains of structures and materials. Within this method, a key aspect lies in the construction and application of an appropriate self-equilibrium stress field(SSF). In the structural shakedown analysis, the SSF is typically constructed by governing equations that satisfy no external force(NEF) boundary conditions. However, we discover that directly applying these governing equations is not suitable for the shakedown analysis of heterogeneous materials. Researchers must consider the requirements imposed by the Hill-Mandel condition for boundary conditions and the physical significance of representative volume elements(RVEs). This paper addresses this issue and demonstrates that the sizes of SSFs vary under different boundary conditions, such as uniform displacement boundary conditions(DBCs), uniform traction boundary conditions(TBCs), and periodic boundary conditions(PBCs). As a result, significant discrepancies arise in the predicted shakedown domain sizes of heterogeneous materials. Built on the demonstrated relationship between SSFs under different boundary conditions, this study explores the conservative relationships among different shakedown domains, and provides proof of the relationship between the elastic limit(EL) factors and the shakedown loading factors under the loading domain of two load vertices. By utilizing numerical examples, we highlight the conservatism present in certain results reported in the existing literature. Among the investigated boundary conditions, the obtained shakedown domain is the most conservative under ***, utilizing PBCs to

关键词： heterogeneous material self-equilibrium stress field(SSF) shakedown analysis effect of boundary conditions

Explosion damage effects of aviation kerosene storage tank under strong ignition

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Defence Technology（防务技术） 2024年第7期37卷 27-38页

作者： Shixiang Song cheng Wang Boyang Qiao Gongtian Gu State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

In order to study the blast damage effects of aviation kerosene storage tanks,the out-field explosion experiments of 8 m3fixed-roof tanks were carried *** fragments,shock wave and fireball thermal radiation of the tank in the presence of bottom oil,half oil and full oil,as well as empty tank,were investigated under internal explosion by various TNT charge contents(1.8 kg,3.5 kg and 6.2 kg).The results showed that the tank roof was the only fragment produced,and the damage forms could be divided into three *** increase of TNT charge content and oil volume enlarged the deformation of the tank,while the hole ratio presented a trend of increase first and then *** H_r,maxand V_(max)values positively increased as increasing the TNT charge content and oil volume(from empty to half oil),but decreased in full *** Pmaxvalues had a progressive increase with the increment of TNT charge content,but not the case with the increase in oil *** development of fireball was divided into three stages:tank roof‘towed'flame,jet flow flame tumbling and rising,and jet flow flame *** Dmaxand Hf,maxvalues both increased as increasing TNT charge content and oil *** oscillation phenomenon of fireball temperature was observed in the cooling *** average temperature of fireball surface was positively correlated with TNT charge content,and negatively correlated with oil volumes.

关键词： Aviation kerosene Storage tank Internal explosion Shock wave Fireball

Al掺杂NiCo_(2)S_(4)电极材料的制备及其电化学性能

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精细化工 2022年第5期39卷 972-978页

作者：周佳刘杰程思远刘璐陈星邓正华谢昆重庆三峡学院三峡库区水环境演变与污染防治重庆高校市级重点实验室重庆404100 东南大学化学化工学院江苏南京211189 重庆市轻合金材料与加工工程技术研究中心重庆404100

以导电碳布(CC)为基底,以NiCl_(2)·6H_(2)O、CoCl_(2)·6H_(2)O为原料,以Al(NO_(3))_(3)·9H_(2)O为Al源,通过两步水热法成功在CC上生长Al掺杂的NiCo_(2)S_(4)复合材料(CC@Al-NiCo_(2)S_(4)).采用SEM、XRD、TEM和XPS对其进行了表征,并对CC@NiCo_(2)S_(4)电极和CC@Al-NiCo_(2)S_(4)电极的电化学性能进行了测试.结果表明,CC@Al-NiCo_(2)S_(4)具有中空纳米管结构,该结构可以提供大量反应活性位点;Al主要以Al^(3+)的形式存在于CC@NiCo_(2)S_(4)中,可以提高CC@NiCo_(2)S_(4)的导电性.当电流密度为1 A/g时,CC@NiCo_(2)S_(4)电极和CC@Al-NiCo_(2)S_(4)电极的比电容分别为844.5和1515.8 F/g;在电流密度为6 A/g下经过10000次循环后,CC@Al-NiCo_(2)S_(4)电极的电容保持率高达87.8%,表明Al掺杂能够显著提高CC@NiCo_(2)S_(4)的比电容和循环稳定性.

关键词： NiCo_(2)S_(4) Al掺杂中空纳米管水热法超级电容器有机电化学

Reduction of dinitrogen to ammonia on doped three-atom clusters Nb_(2)M(M=Sc to Cu & Y to Ag)

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Rare Metals 2024年第8期43卷 3810-3818页

作者： Ran cheng Chao-Nan Cui Zhi-Xun Luo Beijing National Laboratory for Molecular Science(BNLMS) State Key Laboratory for Structural Chemistry of Unstable and Stable SpeciesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Science University of Chinese Academy of SciencesBeijing 100049China

Catalytic reduction of dinitrogen to ammonia under mild conditions remains an attractive topic for the purpose of lowering energy ***-atom metal clusters have been proved an ideal model to explore highly efficient catalysts taking advantage of unique geometric/electronic structures and cooperative active *** a study of N2 activation and reduction on seventeen bimetallic Nb_2M(M=Sc to Cu,and Y to Ag) clusters was *** key processes for ammonia fixation(namely nitrogen activation,hydrogenation,and ammonia desorption) are fully studied,and three preferred systems(Nb_2Ni,Nb_2Rh and Nb_2Pd) are highlighted with outstanding catalytic *** d-σ and d-π~* orbital hybridizations between these metal clusters and N_(2) were demonstrated and the internal association with the N≡N bond activation was *** examining the ammonia synthesis on four chosen Nb_(2)M clusters(M=Fe,Ni,Rh and Pd),it can be elucidated that the distal pathway is more favorable than the alternative pathway in these *** work not only clarifies the N_(2) reduction on the bimetallic Nb_(2)M clusters,but also guides efficient bimetallic catalyst design.

关键词： Three-atom cluster catalysis Three-criteria strategy Nitrogen fixation Ammonia synthesis Theoretical calculations