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Physics-constrained neural network for solving discontinuous interface K-eigenvalue problem with application to reactor physics

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Nuclear Science and Techniques 2023年第10期34卷 178-200页

作者： Qi-Hong Yang Yu Yang Yang-Tao Deng Qiao-lin he he-lin Gong Shi-Quan Zhang School of Mathdematics Sichuan UniversityChengdu 610065China Paris Elite Institute of Technology Shanghai Jiao Tong UniversityShanghai 200240China

Machine learning-based modeling of reactor physics problems has attracted increasing interest in recent *** some progress in one-dimensional problems,there is still a paucity of benchmark studies that are easy to solve using traditional numerical methods albeit still challenging using neural networks for a wide range of practical *** present two networks,namely the Generalized Inverse Power Method Neural Network(GIPMNN)and Physics-Constrained GIPMNN(PC-GIPIMNN)to solve K-eigenvalue problems in neutron diffusion *** follows the main idea of the inverse power method and determines the lowest eigenvalue using an iterative *** PC-GIPMNN additionally enforces conservative interface conditions for the neutron ***,Deep Ritz Method(DRM)directly solves the smallest eigenvalue by minimizing the eigenvalue in Rayleigh quotient form.A comprehensive study was conducted using GIPMNN,PC-GIPMNN,and DRM to solve problems of complex spatial geometry with variant material domains from the fleld of nuclear reactor *** methods were compared with the standard flnite element *** applicability and accuracy of the methods are reported and indicate that PC-GIPMNN outperforms GIPMNN and DRM.

关键词： Neural network Reactor physics Neutron diffusion equation Eigenvalue problem Inverse power method

Selective N-Methylation of N-Methylaniline with CO_(2) and H_(2) over Cu/In_(2)O_(3) Catalyst

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Chinese Journal of Chemistry 2024年第3期42卷 276-282页

作者： Huan Zheng Bo Qian lin he State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhouGansu730000 China University of Chinese Academy of Sciences Beijing100049 China

N-Methylation of amines with CO_(2) and H2 is a potential approach for CO_(2) utilization because N-methylated amines can be used as solvents and organic intermediates. In_(2)O_(3)-supported Cu (Cu/In_(2)O_(3)) acts as an effective heterogeneous catalyst for N-methylation reaction of N-methylaniline (MA) with CO_(2) and H_(2),showing higher N,N-dimethylaniline (DMA) selectivity than other supported Cu catalysts. On one hand,the dispersion of Cu can be improved by the defective In_(2)O_(3) support. On the other hand,In_(2)O_(3) support is active in the dissociative adsorption of CO_(2) through C—O bond breaking. In addition,the H_(2) dissociation ability of In_(2)O_(3) can also be enhanced by Cu. The combination of Cu and In_(2)O_(3) is effective in the activation of CO_(2),the adsorption of intermediate N-methylformanilide (MFA),the hydrogenation of MFA to DMA and the prohibition of C—N bond cleavage side reactions,thereby enhancing the reaction rate of MA conversion and the selectivity to DMA.

关键词： N-Methylation CO_(2) Cu/In_(2)O_(3) Supported catalysts heterogeneous catalysis

Nonlinear stability of rarefaction waves for a viscous radiative and reactive gas with large initial perturbation

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Science China Mathematics 2021年第12期64卷 2637-2666页

作者： Guiqiong Gong lin he Yongkai Liao School of Mathematics and Statistics Wuhan UniversityWuhan 430072China Hubei Key Laboratory of Computational Science Wuhan UniversityWuhan 430072China College of Mathematics Sichuan UniversityChengdu 610064China Institute of Applied Physics and Computational Mathematics Beijing 100088China

We investigate the time-asymptotically nonlinear stability of rarefaction waves to the Cauchy problem of a one-dimensional compressible Navier-Stokes type system for a viscous,compressible,radiative and reactive gas,where the constitutive relations for the pressure p,the speci c internal energy e,the speci c volume v,the absolute temperature θ,and the specific entropy s are given by p=Rθv+aθ^(4)/3,e=C_(v)θ+avθ^(4),and s=C_(v)lnθ+4avθ^(3)/3+Rln v with R>0,C_(v)>0 and a>0 being the perfect gas constant,the speci c heat and the radiation constant,*** such a specific gas motion,a somewhat surprising fact is that,generally speaking,the pressure p(v,s)is not a convex function of the specific volume v and the specific entropy *** so,we show in this paper that the rarefaction waves are time-asymptotically stable for large initial perturbation provided that the radiation constant a and the strength of the rarefaction waves are sufficiently *** key point in our analysis is to deduce the positive lower and upper bounds on the specific volume and the absolute temperature,which are uniform with respect to the space and the time variables,but are independent of the radiation constant a.

关键词： viscous radiative and reactive gas rarefaction waves nonlinear stability large initial perturbation

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A Fuzzy-based Sliding Mode Control Approach for Acceleration Slip Regulation of Battery Electric Vehicle

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Chinese Journal of Mechanical Engineering 2022年第4期35卷 287-297页

作者： Qin Shi Mingwei Wang Zejia he Cheng Yao Yujiang Wei lin he School of Automotive and Transportation Engineering Hefei University of TechnologyHefei 230009China Laboratory of Automotive Intelligence and Electrifcation Hefei University of TechnologyHefei 230009China

Due to quick response and large quantity of electric motor torque,the traction wheels of battery electric vehicle are easy to slip during the initial phase of *** this paper,a sliding mode control approach of acceleration slip regulation is designed to prevent the slip of the traction *** wheel slip ratio is used as the state variable for the formulation of system dynamics *** fuzzy algorithm is utilized to adjust the switch function of sliding mode *** stability and robustness analysis,the sliding mode control law is transferred into C code and downloaded into vehicle control unit,which is validated under wet and dry road *** experimental results with a small overshoot and a quick response during starting indicate that the sliding mode controller has good control efect on the slip ratio *** article proposes an acceleration slip regulation method that improves the safety during acceleration for battery electric vehicle.

关键词： Electric motor torque Wheel slip ratio Stability Fuzzy algorithm Robustness analysis

Thermodynamic modeling of Fe-C-Mn-Si alloys

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Journal of Iron and Steel Research International 2017年第2期24卷 190-197页

作者： Wei-sen Zheng Xiao-gang Lu Yan-lin he lin Li School of Materials Science and Engineering Shanghai University Shanghai 200444 China Department of Materials Science and Engineering KTH Royal Institute of Technology Stockholm 10044 Sweden State Key Laboratory of Advanced Special Steel Shanghai University Shanghai 200072 China

The thermodynamic database of the Fe C Mn-Si system has been developed in the framework of the CALPHAD approach. The sub-ternary systems have been carefully evaluated and revised based on available experimental data. A satisfactory description of the liquid phase in the Fe C-Si system has been obtained. The C Mn Si system was assessed treating the liquid phase as a substitutional solution. Phase equilibria in the C- Mn-Si system, especially those involving the liquid phase, can be well described. Based on the extrapolation of the experimental data in the quaternary system, the Fe Mn Si system has been modified to agree well with experimental data at high temperatures. The comparison between the calculated and measured phase transformation tempera tures confirms the reliability of the present quaternary database. Additionally, the solidification process of Fe-0. 16C-1. 5Mn-1. 5Si （wt. %） alloy was simulated by using the thermodynamic database developed.

关键词： Fe-C-Mn-Si alloy Thermodynamic mode CALPHAD Solidification Partial equilibrium

Energy dissipation and contour integral characterizing fracture behavior of incremental plasticity

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Acta Mechanica Sinica 2011年第2期27卷 251-258页

作者： Qi-lin he lin-Zhi Wu Ming Li Hong-Bo Chen Chen Center for Composite Materials Harbin Institute of Technology 150080 Harbin China

J ep -integral is derived for characterizing the frac- ture behavior of elastic-plastic materials. The J ep -integral differs from Rice’s J-integral in that the free energy density rather than the stress working density is employed to define energy-momentum tensor. The J ep -integral is proved to be path-dependent regardless of incremental plasticity and deformation plasticity. The J epintegral possesses clearly clear physical meaning：（1） the value J ep tip evaluated on the infinitely small contour surrounding the crack tip represents the crack tip energy dissipation; （2） when the global steadystate crack growth condition is approached, the value of J ep farss calculated along the boundary contour equals to the sum of crack tip dissipation and bulk dissipation of plastic zone. The theoretical results are verified by simulating mode I crack problems.

关键词： J-integral · Energy dissipation · Proportional loading · Deformation plasticity · Incremental plasticity

Mobile-Deep Based PCB Image Segmentation Algorithm Research

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Computers, Materials & Continua 2023年第11期77卷 2443-2461页

作者： Lisang Liu Chengyang Ke he lin School of Electronic Electrical Engineering and Physics Fujian University of TechnologyFuzhou350118China State Grid Fujian Power Supply Co. Ltd.Xiapu Power Supply CompanyNingde355100China

Aiming at the problems of inaccurate edge segmentation,the hole phenomenon of segmenting large-scale targets,and the slow segmentation speed of printed circuit boards(PCB)in the image segmentation process,a PCB image segmentation model Mobile-Deep based on DeepLabv3+semantic segmentation framework is ***,the DeepLabv3+feature extraction network is replaced by the lightweight model MobileNetv2,which effectively reduces the number of model parameters;secondly,for the problem of positive and negative sample imbalance,a new loss function is composed of Focal Loss combined with Dice Loss to solve the category imbalance and improve the model discriminative ability;in addition,a more efficient atrous spatial pyramid pooling(E-ASPP)module is *** addition,a more efficient E-ASPP module is proposed,and the Roberts crossover operator is chosen to sharpen the image edges to improve the model accuracy;finally,the network structure is redesigned to further improve the model accuracy by drawing on the multi-scale feature fusion *** experimental results show that the proposed segmentation algorithm achieves an average intersection ratio of 93.45%,a precision of 94.87%,a recall of 93.65%,and a balance score of 93.64%on the PCB test set,which is more accurate than the common segmentation algorithms Hrnetv2,UNet,PSPNet,and PCBSegClassNet,and the segmentation speed is faster.

关键词： PCB boards image segmentation mobile-deep loss function roberts crossover operator

State of charge estimation by square root cubature particle filter approach with fractional order model of lithium-ion battery

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Science China(Technological Sciences) 2022年第8期65卷 1760-1771页

作者： LIU YiWen SHI Qin WEI YuJiang he ZeJia HU XiaoSong he lin School of Automotive and Transportation Engineering Hefei University of TechnologyHefei 230009China The State Key Laboratory of Mechanical Transmissions Chongqing UniversityChongqing 400044China Laboratory of Automotive Intelligence and Electrification Hefei University of TechnologyHefei 230009China

In this paper, a square root cubature particle filter approach was designed to estimate the state of charge of lithium-ion battery,which not only enhanced the numerical stability and guaranteed positive definiteness of the state covariance, but also increased accuracy and decreased computation quantity. Due to the fractional characteristics of the battery capacitance, a fractional order model was used to formulate the lithium-ion battery. Considering the high accuracy and easy convergence, a particle swarm optimization algorithm was utilized to identify the model parameters. The above-mentioned approach was modelled and translated into C code, which was downloaded into battery control unit of battery management system for experimental validation. Two kinds of dynamic cycles were utilized to validate the proposed approach at different temperatures, where both unscent Kalman filter and cubature Kalman filter were compared with the proposed approach. Experimental results indicate that the proposed approach has better accuracy and robustness, and fractional order model is more accurate than integer order ***, the square root cubature particle filter with fractional order model of lithium-ion battery is a good candidate to estimate the state of charge.

关键词： battery management system integer order model particle filter unscent kalman filter cubature Kalman filter

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Thick-Film Negative-Temperature-Coefficient Thermistors with a linear Resistance-Temperature Relation

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Chinese Physics Letters 2013年第10期30卷 143-146页

作者： linG Zhi-Yuan he lin Department of Electronic Materials Science and Engineering College of Materials Science and EngineeringSouth China University of TechnologyGuangzhou 510640 College of Electronic Engineering Dongguan University of TechnologyDongguan 523808

The effect of the resistance R of Mn1.85Co0.3Ni0.85O4(MCN)thick-film negative-temperature-coefficient(NTC)thermistors on temperature T is studied ***,the R–T relation is found to be decided simultaneously by the characteristic of the MCN oxide and the electrode structure of the NTC *** plane end electrodes,the R–T relation is ***,for plane fork electrodes,the R–T relation can be *** clarify the intrinsic mechanism of the linear R–T relation,the electric field distribution in the MCN thick film is *** obtained results suggest that the non-uniform electric field distribution between the electrodes is responsible for the R–T relation linearization.

关键词： film relation linearization