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Impurity formation mechanism of silicon carbide crystals smelted by Acheson process

Journal of Iron and Steel Research International 2024年第6期31卷 1367-1375页

作者： dong Feng Hong-qiang Ru Xu-dong Luo Jie-gang You Ling Zhang School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) Institute of Advanced CeramicsSchool of Materials Science and EngineeringNortheastern UniversityShenyang 110819LiaoningChina Liaoning Institute of Science and Technology Benxi 117004LiaoningChina

In order to further promote the application of SiC refractories in modern steel metallurgy,the occurrence forms and formation mechanism of impurities in SiC crystals smelted by Acheson process were *** techniques of inductively coupled plasma-atomic emission spectrometry,X-ray diffraction,and scanning electron microscopy were combined to examine the types and occurrence forms of impurities in smelted SiC *** results showed that the main impurities in the SiC are free Si,free C,oxides(CaO·Al_(2)O_(3)·2SiO_(2),3Al_(2)O_(3)·2SiO_(2),CaO·SiO_(2) and SiO_(2))and alloy phases(Fe_(x)Si_(y),Fe_(x)Si_(y)Ti_(z) and Fe_(x)Al_(y)Si_(z)).The formation process of impurities during the smelting of SiC can be described as follows:At high temperature,the SiO_(2) and Fe,Ti related oxide impurities present in the raw materials are reduced to Si,Fe,and Ti metal *** the reduction process,the free Si,Fe_(x)Si_(y) and Fe_(x)Si_(y)Ti_(z) are precipitated from the melt during *** Si primarily exists in aggregated form within the SiC crystal,while the alloy phase is predominantly found at the interface between SiC and free Si,with Fe_(x)Si_(y)Ti_(z) embedded within *** the end of the cooling process,other impurity oxides such as Al_(2)O_(3),CaO,and some unreduced SiO_(2) solidify to form calcium-aluminum-silicate glass phases,predominantly located between SiC *** remaining C from the reaction is mainly dispersed as free C within the SiC crystal and at the interface between SiC and free Si.

关键词： Impurity element Formation mechanism Smelted SiC crystal SiC refractory Occurrence form

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Autonomous navigation method of satellite constellation based on adaptive forgetting factors

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Chinese Journal of Aeronautics 2024年第7期37卷 317-332页

作者： dong WANG Jing YANG Kai XIONG School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Science and Technology on Space Intelligent Control Laboratory Beijing Institute of Control EngineeringBeijing 100094China

To address the problem that model uncertainty and unknown time-varying system noise hinder the filtering accuracy of the autonomous navigation system of satellite constellation,an autonomous navigation method of satellite constellation based on the Unscented Kalman Filter with Adaptive Forgetting Factors(UKF-AFF)is *** process noise covariance matrix is estimated online with the strategy that combines covariance matching and adaptive adjustment of forgetting *** adaptive adjustment coefficient based on squared Mahalanobis distance of state residual is employed to achieve online regulation of forgetting factors,equipping this method with more *** intersatellite direction vector obtained from photographic observations is introduced to determine the constellation satellite orbit together with the distance measurement to avoid rank deficiency *** that the number of available measurements varies online with intersatellite visibility in practical applications such as time-varying constellation configurations,the smooth covariance matrix of state correction determined by innovation and gain is adopted and constructed *** analysis of the proposed method is also *** effectiveness of the proposed method is verified by the Monte Carlo simulation and comparison *** estimation accuracy of constellation position and velocity of UKF-AFF is improved by 30%and 44%respectively compared to those of the extended Kalman filter,and the method proposed is also better than other several adaptive filtering methods in the presence of significant model uncertainty.

关键词： Constellation autonomous navigation Unscented Kalman filter Adaptive forgetting factor Model uncertainty Stability analysis

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A General Simulation Method for Complex Deformation of Irregular-Shaped Origami Configurations

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Acta Mechanica Solida Sinica 2024年第1期37卷 90-98页

作者： Zhaochen dong Yichao Zhu Xu Guo State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian 116023China

Most existing treatments for origami-folding simulations have focused on regular-shaped *** article aims to introduce a general strategy for simulating and analyzing the deformation process of irregular shapes by means of computational capabilities *** better simulate origami deformation with folding orders,the concept of plane follow-up is introduced to achieve automated computer simulation of complex folding patterns,thereby avoiding intersection and penetration between *** on the evaluation criteria such as the lowest storage energy with tightening and the fastest pace from tightening to unfolding,the optimal crease distribution patterns for four irregular(‘N’-,‘T’-,‘O’-,and‘P’-shaped)origami configurations are then presented under five *** the dimensions of the origami are fixed,it is discovered that simpler folding patterns lead to faster deformation of the origami *** the folding complexity is fixed,higher strain energy results in more rapid origami expansion.

关键词： Irregular-shaped origami Complex deformation Computer-aided origami design General simulation

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Optimizing urban block morphologies for net-zero energy cities:Exploring photovoltaic potential and urban design prototype

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Building Simulation 2024年第4期17卷 607-624页

作者： Xiaotian Geng dong Xie Zhonghua Gou School of Urban Design Wuhan UniversityWuhanChina

The morphology of urban areas plays a crucial role in determining solar potential,which directly affects photovoltaic capacity and the achievement of net-zero *** study focuses on the City of Melbourne to investigate the utilization of solar energy across different urban densities and proposes optimized *** analysis encompasses blocks with diverse population densities,examining medium and high-density *** utilizing a multi-objective genetic optimization approach,the urban morphology of these blocks is *** findings indicate that low-density blocks exhibit photovoltaic potential ranging from 1 to 6.6 times their total energy *** and high-density blocks achieve photovoltaic potential levels approximately equivalent to 40%-85%of their overall energy ***,significant variations in photovoltaic potential are observed among different urban forms within medium and high-density ***“elevated corners with central valley”prototype is proposed as an effective approach,enhancing the overall photovoltaic potential by approximately 14%.This study introduces novel analytical concepts,shedding light on the intricate relationship between urban morphologies and photovoltaic potential.

关键词： net-zero energy solar energy urban density urban morphology multi-objective optimization photovoltaic potential

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State-Based Opacity Verification of Networked Discrete Event Systems Using Labeled Petri Nets

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1274-1291页

作者： Yifan dong Naiqi Wu Zhiwu Li The authors are with the Institute of Systems Engineering Macao University of Science and TechnologyTaipa 999078MacaoChina

The opaque property plays an important role in the operation of a security-critical system,implying that pre-defined secret information of the system is not able to be inferred through partially observing its *** paper addresses the verification of current-state,initial-state,infinite-step,and K-step opacity of networked discrete event systems modeled by labeled Petri nets,where communication losses and delays are *** on the symbolic technique for the representation of states in Petri nets,an observer and an estimator are designed for the verification of current-state and initial-state opacity,***,we propose a structure called an I-observer that is combined with secret states to verify whether a networked discrete event system is infinite-step opaque or K-step *** to the utilization of symbolic approaches for the state-based opacity verification,the computation of the reachability graphs of labeled Petri nets is avoided,which dramatically reduces the computational overheads stemming from networked discrete event systems.

关键词： infinite system symbolic

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Coordination for a Closed-loop Supply Chain with Recycling Platform Considering Dynamic Setting

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Journal of Systems Science and Systems Engineering 2024年第4期33卷 425-451页

作者： Zehua Xiang Ting Ji Lingfeng dong School of Management Zhejiang UniversityHangzhou310058China School of Business Hangzhou City UniversityHangzhou310015China Alibaba Business College Hangzhou Normal UniversityHangzhou311121China

This paper presents a dynamic closed-loop supply chain(CLSC)model,incorporating a manufacturer,a retailer,and an internet recycling platform(IRP),utilizing differential game theory while considering the forgetting effect of *** model encompasses factors such as the quality level of used products and Big Data marketing(BDM),comparing optimal equilibriums under decentralized and cooperative decision *** effectively coordinate the dynamic CLSC at each time point,we propose a revenue-sharing and cost-sharing(RSCS)combined *** addition to ensuring reasonable sharing of revenues and costs,this contract allows the manufacturer to flexibly adjust wholesale prices for final products and transfer prices for used products in order to distribute profits appropriately and achieve Pareto optimality within the CLSC ***,our results indicate that there exists a threshold for Big Data marketing efficiency;high-efficiency BDM not only facilitates increased recycling on Internet platforms but also reduces unit recycling costs for ***,when implementing the combined contract,Big Data marketing efficiency does not impact the transfer price paid by manufacturers to Internet recycling platforms.

关键词： Big Data marketing differential game closed-loop supply chain coordination internet recycling platform

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A New Method for Solving Nonlinear Partial Differential Equations Based on Liquid Time-Constant Networks

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Journal of Systems Science & Complexity 2024年第2期37卷 480-493页

作者： SUN Jiuyun dong Huanhe FANG Yong College of Mathematics and Systems Science Shandong University of Science and TechnologyQingdao 266590China

In this paper,physics-informed liquid networks(PILNs)are proposed based on liquid time-constant networks(LTC)for solving nonlinear partial differential equations(PDEs).In this approach,the network state is controlled via ordinary differential equations(ODEs).The significant advantage is that neurons controlled by ODEs are more expressive compared to simple activation *** addition,the PILNs use difference schemes instead of automatic differentiation to construct the residuals of PDEs,which avoid information loss in the neighborhood of sampling *** this method draws on both the traveling wave method and physics-informed neural networks(PINNs),it has a better physical ***,the KdV equation and the nonlinear Schr¨odinger equation are solved to test the generalization ability of the *** the best of the authors’knowledge,this is the first deep learning method that uses ODEs to simulate the numerical solutions of PDEs.

关键词： Nonlinear partial differential equations numerical solutions physics-informed liquid networks physics-informed neural networks

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On Minor Left Prime Factorization Problem for Multivariate Polynomial Matrices

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Journal of Systems Science & Complexity 2024年第3期37卷 1295-1307页

作者： LU dong WANG Dingkang XIAO Fanghui School of Mathematics Southwest Jiaotong UniversityChengdu 610031China KLMM Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China MOE-LCSM School of Mathematics and StatisticsHunan Normal UniversityChangsha 410081China

A new necessary and sufficient condition for the existence of minor left prime factorizations of multivariate polynomial matrices without full row rank is *** key idea is to establish a relationship between a matrix and any of its full row rank *** on the new result,the authors propose an algorithm for factorizing matrices and have implemented it on the computer algebra system *** examples are given to illustrate the effectiveness of the algorithm,and experimental data shows that the algorithm is efficient.

关键词： Free modules Grobner bases minor left prime(MLP) multivariate polynomial matrices polynomial matrix factorizations

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C@Ag core‒shell structure as lubricating additives towards high efficient lubrication

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Friction 2024年第9期12卷 1991-2003页

作者： dong AO Xiaoqiang FAN Minhao ZHU Key Laboratory of Advanced Technologies of Materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Tribology Research Institute School of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Efficient cooperative lubrication can be achieved via the introduction of core‒shell structure lubricant additives with hard core and soft shell,for obtaining the expected anti-wear performance from the structural changes in the friction *** this study,C@Ag microspheres with a core‒shell structure were prepared by the redox method with carbon spheres as the core and Ag nanoparticles as the *** tribological behaviors as base oil(G1830)additive with different concentrations were investigated in *** with base oil,the addition of C@Ag particles at 0.5 wt%can reduce the coefficient of friction(COF)and wear volume(Wv)up to 15.5%and 88%,*** importantly,C@Ag particles provide superior lubrication performance to single additive(like carbon sphere(CS)and Ag nanoparticle).C@Ag core‒shell particles contribute to the formation of tribo-film by melt bonding of flexible Ag and carbon sphere(CS)toward excellent self-repair performance and high-efficiency ***,core‒shell structural nanoparticles with hard-core and soft-shell hold bright future for high-performance lubrication application.

关键词： C@Ag microspheres tribo-film self-repair performance high-efficiency lubrication

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Analysis of the Oscillatory Flows of Multiple Shock Waves in a Constant Area Duct

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Journal of Thermal Science 2024年第3期33卷 794-806页

作者： K JAMES Jintu KIM Heuy dong Department of Mechanical Engineering Andong National UniversityAndong36729Republic of Korea CAD-IT Korea Co. Ltd.Seoul08591Republic of Korea

The oscillatory response of multiple shock waves to downstream perturbations in a supersonic flow is studied numerically in a rectangular *** shock waves are formed inside the duct at a shock Mach number of *** duct has an exit height of H,and the effect of duct resonance on multiple shock oscillations is investigated by attaching exit ducts of lengths 0H,50H,and *** downstream disturbance frequency varied from 10 Hz to 200 Hz to explore the oscillation characteristics of the multiple shock *** oscillatory response of shock waves under self-excited and forced oscillation conditions are analyzed in terms of wall static pressure,shock train leading-edge location,shock train length,and the size of the separation *** extent of the initial shock location increases with an increase in exit duct length for the self-excited oscillation *** analysis of the shock train leading edge and the spectral analysis of wall static pressure variations are *** variation in the shock train length is analyzed using the pressure ratio method for self-excited as well as forced *** RMS amplitude of the normalized shock train length(ζ_(ST))increases with an increase in the exit duct length for the self-excited oscillation *** the downstream perturbation frequency is increased,ζ_(ST)is decreased for exit duct *** all exit duct designs and downstream forcing frequencies,the size of the separation bubble grows and shrinks during the shock oscillations,demonstrating the dependence on duct resonance and forced oscillations.

关键词： shock train downstream disturbance supersonic flow shock wave boundary layer interaction duct resonance flow separation

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