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High Voltage 2023年第5期8卷 1041-1054页

作者： Lijun Zhou Jun Zhang Zhixin Li Rongting Wen Dongyang Wang Jiekang Wu Huiling Tang School of Electrical Engineering Southwest Jiaotong UniversityChengduChina School of Automation Guangdong University of TechnologyGuangzhouChina School of Physics and Optoelectronic Engineering Guangdong University of TechnologyGuangzhouChina

Frequency domain dielectric spectroscopy(FDS)is an effective method reflecting the changes of ageing status of silicone oil‐immersed insulation *** better evaluating the ageing status of silicone oil‐immersed insulation paper,an evaluation method was studied by analysing the ageing kinetic model and results of ***,the method to separate the different polarization losses and conductivity loss from the results of FDS was ***,based on the idea of ageing correction translation coefficient and timevarying pre exponential factor,the zero order ageing dynamic model was modified,which combines the ageing kinetic model with the results of ***,the evaluation method for the degree of polymerisation(DP)of silicone oil‐immersed paper was proposed,and experiments were conducted to obtain the parameters in the modified model and then to verify the proposed *** results show that the proposed method can be used to evaluate the DP effectively.

关键词： immersed insulation spectroscopy

Comparative study on foundation treatment methods of immersed tunnels in China

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Frontiers of Structural and Civil Engineering 2020年第1期14卷 82-93页

作者： Shaochun WANG Xuehui ZHANG Yun BAI Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

Based on engineering practices of four typical traffic immersed tunnels built in China,this paper details the features of the four dominant foundation treatment methods for immersed tunnel construction:pile foundation,sand flow foundation,grouting foundation,and gravel bedding *** stress time-history of different method are specified first,plus a summary of settlement assessment method for foundation quality ***,a comprehensive comparison of settlement and cost of these four foundation treatment methods is conducted to highlights the specific merits,disadvantages and conditions encountered in each foundation treatment method,based on real projects *** findings of this article could henceforth be applied to foundation treatment work in immersed tube tunnel construction.

关键词： foundation treatment method immersed tunnel subsoil stress settlement

Wall-modeling for large-eddy simulation of flows around an axisymmetric body using the diffuse-interface immersed boundary method

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Applied Mathematics and Mechanics(English Edition) 2019年第3期40卷 305-320页

作者： Beiji SHI Xiaolei YANG Guodong JIN Guowei HE Shizhao WANG The State Key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences School of Engineering Sciences University of Chinese Academy of Sciences Department of Civil Engineering College of Engineering and Applied Sciences Stony Brook University

A novel method is proposed to combine the wall-modeled large-eddy simulation(LES) with the diffuse-interface direct-forcing immersed boundary(IB) *** new developments in this method include:(i) the momentum equation is integrated along the wall-normal direction to link the tangential component of the effective body force for the IB method to the wall shear stress predicted by the wall model;(ii) a set of Lagrangian points near the wall are introduced to compute the normal component of the effective body force for the IB method by reconstructing the normal component of the velocity. This novel method will be a classical direct-forcing IB method if the grid is fine enough to resolve the flow near the wall. The method is used to simulate the flows around the DARPA SUBOFF model. The results obtained are well comparable to the measured experimental data and wall-resolved LES results.

关键词： wall model large-eddy simulation(LES) immersed boundary(IB)method diffuse-interface

Two-grid methods for semi-linear elliptic interface problems by immersed finite element methods

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Applied Mathematics and Mechanics(English Edition) 2019年第11期40卷 1657-1676页

作者： Yang WANG Yanping CHEN Yunqing HUANG Ying LIU School of Mathematics and Computational Science Xiangtan UniversityXiangtan 411105Hunan ProvinceChina School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China College of Science Hunan Agricultural UniversityChangsha 410128China

In this paper,two-grid immersed finite element (IFE) algorithms are proposed and analyzed for semi-linear interface problems with discontinuous diffusion coefficients in two *** of the advantages of finite element (FE) formulation and the simple structure of Cartesian grids,the IFE discretization is used in this ***-grid schemes are formulated to linearize the FE *** is theoretically and numerically illustrated that the coarse space can be selected as coarse as H =O(h^1/4)(or H =O(h^1/8)),and the asymptotically optimal approximation can be achieved as the nonlinear *** a result,we can settle a great majority of nonlinear equations as easy as linearized *** order to estimate the present two-grid algorithms,we derive the optimal error estimates of the IFE solution in the L^p *** experiments are given to verify the theorems and indicate that the present two-grid algorithms can greatly improve the computing efficiency.

关键词： two-grid method interface problem finite element method immersed interface

Comparison of AC breakdown characteristics on insulation paper (pressboard) immersed by three-element mixed insulation oil and mineral oil

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High Voltage 2020年第3期5卷 298-305页

作者： Dawei Feng Jian Hao Lijun Yang Ruijin Liao Xin Chen Jian Li State Key Laboratory of Power Transmission Equipment and System Security and New Technology School of Electrical EngineeringChongqing UniversityChongqing 400044People's Republic of China

Insulation oil is an important dielectric in power devices,and many studies on mixed insulation oil have been conducted in recent years to improve the performance of insulation *** replace mineral oil directly,the authors previously developed a novel three-element mixed insulation oil successfully;the main parameters of which satisfy the IEC 60296-2012 standard for mineral *** the present study,the AC breakdown properties of insulation paper(pressboard)immersed by the new mixed oil and naphthenic mineral oil were *** both insulation oils,the increase in temperature cannot significantly reduce the breakdown strength of oil-immersed insulation paper(pressboard)at a low moisture content,and the increment of moisture content cannot reduce the breakdown voltage at a low temperature(25℃).The breakdown voltage decreases only when the two factors increase *** the mixed and mineral oils,the AC breakdown voltage of oilimmersed paper(pressboard)with different thicknesses has significant *** mineral oil has a high breakdown voltage for the thin insulation paper,whereas the mixed oil has a high breakdown voltage when the thickness of the insulation paper(pressboard)exceeds 0.2 *** phenomenon is mainly caused by the breakdown field strength that varies with the increase of dielectric thickness and the different change trends of paper(pressboard)immersed with the mixed and the mineral ***,the stack of thin multilayer insulation paper enables the mixed oil-immersed paper to have a higher breakdown strength than the mineral oil-immersed *** the AC breakdown voltage of oil-immersed pressboard with an oil-gap structure,the mixed oil is comprehensively superior to the mineral oil due to its larger relative permittivity.

关键词： insulation immersed breakdown

Polarization loss analysis and ageing characterisation of transformer oil-immersed insulation by using decoupled frequency domain spectroscopy

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High Voltage 2022年第3期7卷 575-585页

作者： Xianhao Fan Jiefeng Liu Yiyi Zhang Zheshi Ding Qingyin Wang Guangxi Key Laboratory of Intelligent Control and Maintenance of Power Equipment Guangxi UniversityNanningGuangxiChina

The polarization information contained in the frequency-domain spectroscopy(FDS)could be utilised for characterising the ageing degree of transformer oil-immersed ***,the polarization information will be obscured by its conductance effect,it is thus hard to analyse the polarization behaviour by using the traditional FDS *** this issue,an alternative approach is proposed to analyse the polari-zation information using FDS decoupled by logarithmic-derivative spectroscopy(LDS).Findings proved that the polarization loss information generated by polarization behaviour can be separated from the total dispersion *** proposed feature pa-rameters are later used to analyse the polarization loss information under ageing ***,the polarization loss surface is constructed by using these feature parameters to characterise the ageing degrees of oil-immersed ***,the potential possibility of using the proposed method to analyse the polarization loss and ageing degree are respectively discussed.

关键词： immersed polarization character

An adaptive version of ghost-cell immersed boundary method for incompressible flows with complex stationary and moving boundaries

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Science China(Physics,Mechanics & Astronomy) 2010年第5期53卷 923-932页

作者： WANG Liang1 & WU ChuiJie2,3 1 School of Science,PLA University of Science and Technology,Nanjing 211101,China 2 State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian University of Technology,Dalian 116024,China 3 School of Aeronautics and Astronautics,Dalian University of Technology,Dalian 116024,China 1. School of Science PLA University of Science and Technology Nanjing 211101 China2. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China3. School of Aeronautics and Astronautics Dalian University of Technology Dalian 116024 China

An adaptive version of immersed boundary method for simulating flows with complex stationary and moving boundaries is *** method employs a ghost-cell methodology which allows for a sharp representation of the immersed *** simplify the implementation of the methodology,a volume-of-fluid method is introduced to identify the immersed *** addition,the domain is spatially discretized using a tree-based discretization which is relatively simple to implement a fully flexible adaptive refinement ***,the methodology is validated by comparing it with numerical and experimental results on three cases:(1) the flow passing a circular cylinder at Re=40 and Re=100,(2) a periodic oscillation of a circular cylinder in fluid at rest and(3) the self-propelled fish-like swimming at Re=6400.

关键词： adaptive mesh refinement ghost-cell immersed boundary method moving boundaries

Ageing characteristics and lifetime model of oil-paper insulation for oil-immersed paper condenser bushing

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High Voltage 2021年第2期6卷 278-290页

作者： Sihang Gao Lijun Yang Tingjing Ke Key Laboratory of Industrial Internet of Things and Networked Control Ministry of EducationChongqing University of Posts and TelecommunicationsChongqingChina State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing UniversityChongqingChina State Grid Chongqing Electric Power Company Chongqing ChongqingChina

This study extensively investigated the ageing characteristics and lifetime model of oil-paper insulation for oil-immersed paper condenser *** accelerated thermal and electrothermal ageing experiments of oil-immersed paper condenser bushing were con-ducted *** properties of oil-paper insulation during the ageing process were *** showed that descending speed of degree of polymerization of the innermost and the outermost layer paper was higher than that of middle layer paper,the difference in water content on different paper layers caused varying deterioration *** aluminium foil contributed to a surge in aluminium dissolution in oil,further accelerating the ageing of *** on the obtained degree of polymerization data under thermal ageing at 90°C,100°C and 130°C,the lifetime model of oil-paper insu-lation for condenser bushing model was *** addition,the surface breakdown of the scale model of bushing occurred after 133 days ageing,the properties of bushing decreased gradually during the ageing process and sharply after the *** of polymerization deviation of different paper layers in bushing between calculated value according to the above lifetime model and actual value of bushing after the breakdown was less than 6%,further verifying the validity of lifetime model.

关键词： lifetime immersed insulation

Parallel computing strategy for the simulation of particulate flows with immersed boundary method

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Science China(Technological Sciences) 2008年第8期51卷 1169-1176页

作者： WANG ZeLi FAN JianRen LUO Kun State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou 310027China

A parallel computing strategy for the simulation of particulate flows with immersed boundary technique is proposed. This strategy can deal with the coupling between fluid and particle easily when particle crosses the boundaries of sub-domains which are decomposed from original computational domain. And a two- dimen- sional circular particle settling in a closed rectangular domain is simulated with the parallel technique and immersed boundary method to validate the parallel effi- ciency.

关键词： parallel computing immersed boundary method particulate flows

OpenIFEM:A High Performance Modular Open-Source Software of the immersed Finite Element Method for Fluid-Structure Interactions

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Computer Modeling in Engineering & Sciences 2019年第4期119卷 91-124页

作者： Jie Cheng Feimi Yu Lucy T.Zhang Department of Mechanical Aerospace and Nuclear Engineering Rensselaer Polytechnic InstituteTroyNY12180USA

We present a high performance modularly-built open-source *** is a C++implementation of the modified immersed finite element method(mIFEM)to solve fluid-structure interaction(FSI)*** software is modularly built to perform multiple tasks including fluid dynamics(incompressible and slightly compressible fluid models),linear and nonlinear solid mechanics,and fully coupled fluid-structure *** of open-source software packages are restricted to certain discretization methods;some are under-tested,under-documented,and lack modularity as well as *** is designed and built to include a set of generic classes for users to adapt so that any fluid and solid solvers can be coupled through the FSI *** addition,the package utilizes well-developed and tested *** also comes with standard test cases that serve as software and algorithm *** software can be built on cross-platform,i.e.,Linux,Windows,and Mac OS,using *** parallelization is also implemented for high-performance computing for large-sized *** is documented using Doxygen and publicly available to download on *** is expected to benefit the future development of FSI algorithms and be applied to a variety of FSI applications.

关键词： immersed finite element method open-source parallelization fluid-structure interaction adaptive mesh refinement