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Finite Element Method for Transient Electric Field by Using Indirect Laplace Transform with High Accuracy

CSEE Journal of Power and Energy Systems 2024年第1期10卷 401-411页

作者： teng wen Xiang Cui Xuebao Li Sijia Liu Zhibin Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China China Electric Power Planning&Engineering Institute Beijing 100120China

This paper focuses on the finite element method in the complex frequency domain(CFD-FEM)for the transient electric field.First,the initial value and boundary value problem of the transient electric field under the electroquasistatic field in the complex frequency domain is given.In addition,the finite element equation and the constrained electric field equation on the boundary are derived.Secondly,the indirect algorithm of the numerical inverse Laplace transform is introduced.Based on it,the calculation procedures of the CFD-FEM are illustrated in detail.Thirdly,the step response,zero-state response under the positive periodic square waveform(PPSW)voltage,and the zero-input response by the CFD-FEM with direct algorithm and indirect algorithm are compared.Finally,the reason for the numerical oscillations of the zero-state response under the PPSW voltage is analyzed,and the method to reduce oscillations is proposed.The results show that the numerical accuracy of the indirect algorithm of the CFD-FEM is more than an order of magnitude higher than that of the direct algorithm when calculating the step response of the transient electric field.The proposed method can significantly reduce the numerical oscillations of the zero-state response under the PPSW voltage.The proposed method is helpful for the calculation of the transient electric field,especially in the case of frequency-dependent parameters.

关键词： Electroquasistatic field transient electric field finite element method complex frequency domain numerical Laplace transform

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Brain Pathology in COVID-19:Clinical Manifestations and Potential Mechanisms

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Neuroscience Bulletin 2024年第3期40卷 383-400页

作者： Zhixing Xu Hui Wang Siya Jiang Jiao teng Dongxu Zhou Zhong Chen Chengping wen Zhenghao Xu First School of Clinical Medicine Zhejiang Chinese Medical UniversityHangzhou 310053China School of Pharmaceutical Sciences Zhejiang Chinese Medical UniversityHangzhou 310053China Second School of Clinical Medicine Zhejiang Chinese Medical UniversityHangzhou 310053China Afliated Lin’an People’s Hospital of Hangzhou Medical College First People’s Hospital of Hangzhou Lin’an DistrictLin’anHangzhou 311300China School of Life Sciences Zhejiang Chinese Medical UniversityHangzhou 310053China Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province College of Pharmaceutical ScienceZhejiang Chinese Medical UniversityHangzhou 310053China Laboratory of Rheumatology and Institute of TCM Clinical Basic Medicine College of Basic Medical ScienceZhejiang Chinese Medical UniversityHangzhou 310053China

Neurological manifestations of coronavirus disease 2019(COVID-19)are less noticeable than the respiratory symptoms,but they may be associated with disability and mortality in COVID-19.Even though Omicron caused less severe disease than Delta,the incidence of neurological manifestations is similar.More than 30%of patients experienced“brain fog”,delirium,stroke,and cognitive impairment,and over half of these patients presented abnormal neuroimaging outcomes.In this review,we summarize current advances in the clinical findings of neurological manifestations in COVID-19 patients and compare them with those in patients with influenza infection.We also illustrate the structure and cellular invasion mechanisms of SARS-CoV-2 and describe the pathway for central SARS-CoV-2 invasion.In addition,we discuss direct damage and other pathological conditions caused by SARS-CoV-2,such as an aberrant interferon response,cytokine storm,lymphopenia,and hypercoagulation,to provide treatment ideas.This review may offer new insights into preventing or treating brain damage in COVID-19.

关键词： COVID-19 SARS-CoV-2 Brain Neurological pathology

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Mixed D-vine copula-based conditional quantile model for stochastic monthly streamflow simulation

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Water Science and Engineering 2024年第1期17卷 13-20页

作者： wen-zhuo Wang Zeng-chuan Dong Tian-yan Zhang Li Ren Lian-qing Xue teng Wu College of Water Resources and Hydrology Hohai UniversityNanjing 210098China Yellow River Research Center Hohai UniversityNanjing 210098China

Copula functions have been widely used in stochastic simulation and prediction of streamflow.However,existing models are usually limited to single two-dimensional or three-dimensional copulas with the same bivariate block for all months.To address this limitation,this study developed a mixed D-vine copula-based conditional quantile model that can capture temporal correlations.This model can generate streamflow by selecting different historical streamflow variables as the conditions for different months and by exploiting the conditional quantile functions of streamflows in different months with mixed D-vine copulas.The up-to-down sequential method,which couples the maximum weight approach with the Akaike information criteria and the maximum likelihood approach,was used to determine the structures of multivariate Dvine copulas.The developed model was used in a case study to synthesize the monthly streamflow at the Tangnaihai hydrological station,the inflow control station of the Longyangxia Reservoir in the Yellow River Basin.The results showed that the developed model outperformed the commonly used bivariate copula model in terms of the performance in simulating the seasonality and interannual variability of streamflow.This model provides useful information for water-related natural hazard risk assessment and integrated water resources management and utilization.

关键词： Stochastic monthly streamflow simulation Mixed D-vine copula Conditional quantile model Up-to-down sequential method Tangnaihai hydrological station

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Embedding Tensors on 3-Hom-Lie Algebras

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Journal of Mathematical Research with Applications 2024年第2期44卷 187-198页

作者： wen teng Jiulin JIN Yu ZHANG School of Mathematics and Statistics Guizhou University of Finance and Economics School of Science Guiyang University

In this paper, we introduce the notion of embedding tensors on 3-Hom-Lie algebras and show that embedding tensors induce naturally 3-Hom-Leibniz algebras. Moreover, the cohomology theory of embedding tensors on 3-Hom-Lie algebras is defined. As an application,we show that if two linear deformations of an embedding tensor on a 3-Hom-Lie algebra are equivalent, then their infinitesimals belong to the same cohomology class in the first cohomology group.

关键词： 3-Hom-Lie algebra embedding tensor representation cohomology deformation

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Tuning the electronic conductance of REHx（RE = Nd, Ce, Pr） by structural deformation

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Journal of Energy Chemistry 2024年第8期95卷 440-445页

作者： Shangshang Wang Weijin Zhang Jirong Cui Shukun Liu Hong wen Jianping Guo teng He Hujun Cao Ping Chen Dalian Institute of Chemical Physics Chinese Academy of Sciences Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences State Key Laboratory of Catalysis Chinese Academy of Sciences

Hydride ion（H-） conductors have drawn much attention due to their potential applications in hydrideion-based devices. Rare earth metal hydrides（REHx） have fast H-conduction which, unfortunately, is accompanied by detrimental electron conduction preventing their application as ion conductors. Here,REHx（RE = Nd, Ce, and Pr） with varied grain sizes, rich grain boundaries, and defects have been prepared by ball milling and subsequent sintering. The electronic conductivity of the ball-milled REHxsamples can be reduced by 2–4 orders of magnitude compared with the non-ball-milled samples. The relationship of electron conduction and miscrostructures in REHxis studied and discussed based on experimental data and previously-proposed classical and quantum theories. The H-conductivity of all REHxis about 10-4to 10-3S cm-1at room temperature, showing promise for the development of H-conductors and their applications in clean energy storage and conversion.

关键词： Crystal defect Electron conduction Electron scattering Hydride ion conduction Nanosized grain

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Ultracycles consisting of macrocycles

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Chinese Chemical Letters 2024年第5期35卷 183-188页

作者： wen-Hui Mi teng-Yu Huang Yu-Fei Ao Xu-Dong Wang Qi-Qiang Wang De-Xian Wang Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Molecular Recognition and FunctionInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Presented here is a one-pot strategy starting from rationally designed macrocyclic precursors for the diverse construction of sophisticated ultracycles.The type and amount of the base were found to significantly influence the macrocyclization outcome.The use of 4.0 equiv.CsF resulted in ultracycles of both types A and B while the presence of CsF larger than 6.0 equiv.produced only type B ultracycles.Existence of anion template increased the total yields and affected the distribution of the ultracycles.The ultracycles can accommodate large organic dicarboxylates anions via multiple anion-πand hydrogen bonds,and show selectivity to the size-matched heptanedioate(C7^(2−)).Based on all possible species and relevant equilibrium constants as well as material and charge balances,a numerical iterative algorithm was developed and applied to fit the association constants of B2H with dicarboxylates from glutarate(C5^(2−))to octanedioate(C8^(2−)),which gave association constants up to 10^(3) L/mol.

关键词： Ultracycles Diversity-oriented synthesis Anion recognition Anion-πinteraction

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Characterization of Electric Field Distribution Within High Voltage Press-packed IGBT Submodules Under Conditions of Repetitive Turn-on and Turn-off

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CSEE Journal of Power and Energy Systems 2022年第2期8卷 609-620页

作者： teng wen Xiang Cui Sijia Liu Xuebao Li Zhibin Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China

The high-voltage high-power press-packed IGBT(PPI)devices are the key component of the DC transmission apparatus.A PPI device is composed of several PPI submodules.In general,the PPI submodule works in a state of repetitive turn-on and turn-off,and the corresponding working voltage is the positive periodic square waveform(PPSW)voltage,which is much different from the conventional AC or DC voltage.In addition,insulation capability is one of the most critical challenges in the design and fabrication of PPI devices.To improve the insulation capability of the device,composite insulation structures with multiple dielectrics are usually employed.Under the PPSW voltage,it is essential to analyze the transient electric field to solve the insulation challenge of the PPI devices.However,the electric field of the PPI is often calculated under the electrostatic field or DC field.Moreover,the transient characteristics of the electric field are ignored.Therefore,this paper focuses on the analysis of the transient characteristics of the electric field of the PPI submodule under the PPSW voltage.The influences of the waveform parameters of the PPSW voltage on the transient characteristics are demonstrated in detail.This study is significant for the insulation analysis and design of the PPIs.

关键词： Electroquasistatic field FEM IGBT positive periodic square waveform voltage transient electric field

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Time-domain Finite Element Method for Transient Electric Field and Transient Charge Density on Dielectric Interface

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CSEE Journal of Power and Energy Systems 2022年第1期8卷 143-154页

作者： teng wen Xiang Cui Xuebao Li Hao Ma Zhibin Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China

This paper is devoted to solving the transient electric field and transient charge density on the dielectric interface under the electroquasistatic(EQS)field conditions with high accuracy.The proposed method is suitable for both 2-D and 3-D applications.Firstly,the governing equations represented by scalar electric potential are discretized by the nodal finite element method(FEM)in space and the finite difference method in time.Secondly,the transient constrained electric field equation on the boundary(TCEFEB)is derived to calculate the normal component of the transient electric field intensities on the Dirichlet boundary and dielectric interface as well as the transient charge density on the dielectric interface.Finally,a 2-D numerical example is employed to demonstrate the validity of the proposed method.Furthermore,the comparisons of the numerical accuracy of the proposed method in this paper with the existing FEMs for electric field intensity and charge density on the dielectric interface are conducted.The results show that the numerical accuracy of the proposed method for calculating the normal component of transient electric field intensities on the Dirichlet boundary and dielectric interface as well as the transient charge density on the dielectric interface is close to that of nodal electric potential and an order of magnitude higher than those of existing FEMs.

关键词： Electroquasistatic field composite insulation structure transient constrained electric field equation on the boundary finite element method interface charge time-domain

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Transient electric field of the combined insulation structure under positive periodic square waveform voltage:Analytical analysis and application

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High Voltage 2022年第5期7卷 877-889页

作者： teng wen Xiang Cui Xuebao Li Sijia Liu Zhibin Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina

The working voltage of the high-voltage high-power electronic devices is the positive periodic square waveform(PPSW)voltage,which is much different from the conventional AC or DC voltage.For the composite insulation structure of devices,it is important to analyse the transient electric field under the PPSW voltage.However,the existing investigations are often conducted under the electrostatic field due to the high frequency of the PPSW voltage.Thus,the transient characteristics of the electric field are missed.To obtain some qualitative conclusions,this paper focusses on the theoretical analysis of the transient characteristics of electric field for the composite insulation structure under the PPSW voltage.First,the formula of the electric field intensity and the interfacial charge density are derived analytically.Second,the influence of the cycle and the duty cycle on the transient characteristics are investigated.Third,the maximum of the electric field intensity and the interfacial charge density in the positive square waveform steady-state are discussed in detail.Besides,the engineering calculation methods for obtaining these maximum values are also suggested.Lastly,an actual model is employed to testify the validity of the analytical analysis.This work is significant for the numerical calculation of the transient electric field of composite insulation structure under the PPSW voltage in engineering.

关键词： composite insulation field

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Lie-Yamaguti代数的相对微分算子

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数学年刊（A辑） 2024年第1期45卷 39-52页

作者：腾文贵州财经大学数学与统计学院贵阳550025

本文研究Lie-Yamaguti代数的相对微分算子.首先给出Lie-Yamaguti代数上相对微分算子的概念并给出等价刻画.随后,引入Lie-Yamaguti代数上相对微分算子的上同调.最后,讨论Lie-Yamaguti代数上相对微分算子的无穷小形变.

关键词： Lie-Yamaguti代数相对微分算子上同调形变

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