检索结果-南通市图书馆

Electromagnetic anisotropic homogeneous model for eddy-current field in single-phase wound core

在线全文

学校读者我要写书评

暂无评论

High Voltage 2024年第1期9卷 172-181页

作者： Lijun Zhou Woyang Li Yingyi Xia Jiawei Chen Chenqingyu Zhang Xiaohu Cai Lei Guo Dongyang Wang school of Electrical Engineering Southwest Jiaotong UniversityChengduChina

The analysis of the eddy-current field in the wound core widely used in the field of transformer energy conservation is taken as the *** the homogenisation idea to consider the unique geometry of the wound core and features of its equivalent multi-stage circular cross-section magnetic boundary,a homogeneous model consisting of a columnar material with continuous homogeneous electromagnetic anisotropy is established by deriving the maxwell equations of the magnetic quasi-static field in the columnar coordinate ***,a homogeneous fine element model for the eddycurrent field in the wound core is established and the accuracy of the model has been verified by the test *** result shows that the homogeneous model can be effectively used for the analysis of the eddy-current field in the wound core,and the error of calculating the eddy-current loss under different excitation conditions is less than 6%under the premise of extremely saving the engineering calculation cost,which will help improve the operational performance of the wound core and contribute to the energysaving goal of the high-voltage equipment.

关键词： anisotropic coordinate excitation

A generalized presentation of multi-caloric effects based on exterior derivative theory and its applications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第8期76卷 156-163页

作者： Jun Yin school of Materials Science and Engineering Nankai UniversityTianjin 300350China school of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350108China

The emerging concept of multi-caloric effects, introduced in 2010, entails the application of multiple interplay fields to a thermodynamic system. While multi-caloric effects are the main focus of experimental endeavors, theoretical considerations fall short of providing a thorough understanding. This paper introduces a comprehensive presentation on multi-caloric effects,employing the method and theory of exterior derivative formations. It addresses every aspect of thermodynamic systems, showcasing its applicability to multi-caloric materials(both singlephase and multi-phase materials), and its adaptability to different scenarios(either in single or multiple force fields). The formulation of maxwell relationships, characterized by their generality and universality, enables a clear prediction in entropy and temperature, facilitating a distinct identification between independent and interdependent contributions from multi-caloric effects. These insights hold significant importance in designing and developing specialized thermodynamic materials, optimizing functional performances and exploring innovative mechanisms.

关键词： multicaloric effects maxwell relations isothermal entropy adiabatic temperature

Effect of ion stress on properties of magnetized plasma sheath

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2024年第2期26卷 1-12页

作者：陈龙崔作君高维富段萍阚子晨檀聪琦陈俊宇 school of Science Dalian Maritime UniversityDalian 116026People's Republic of China

In the plasma sheath, there is a significant gradient in ion velocity, resulting in strong stress on ions treated as a fluid. This aspect has often been neglected in previous sheath studies. This study is based on the Braginskii plasma transport theory and establishes a 1D3V sheath fluid model that takes into account the ion stress effect. Under the assumption that ions undergo both electric and diamagnetic drift in the presheath region, self-consistent boundary conditions,including the ion Bohm velocity, are derived based on the property of the Sagdeev ***, assuming that the electron velocity at the wall follows a truncated maxwell distribution, the wall floating potential is calculated, leading to a more accurate sheath thickness estimation. The results show that ion stress significantly reduces the sheath thickness, enhances ion Bohm velocity, wall floating potential, and ion flux at the wall. It hinders the acceleration of ions within the sheath, leading to notable alterations in the particle density profiles within the sheath. Further research indicates that in ion stress, bulk viscous stress has the greatest impact on sheath properties.

关键词： magnetized plasma sheath ion stress Bohm criterion

Teukolsky-like equations with various spins in spherically symmetric spacetime

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第8期48卷 213-223页

作者： Ya Guo Hiroaki Nakajima Wenbin Lin school of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610031China school of Mathematics and Physics University of South ChinaHengyang 421001China

We study wave equations with various spins on the background of a general spherically symmetric *** obtain the unified expression of the Teukolsky-like master equations and the corresponding radial equations with the general *** also discuss the gauge dependence in the gravitational-wave equations,which have appeared in previous studies.

关键词： gravitational wave effective one-body dynamics Teukolsky equation wave equations Klein-Gordon equation Weyl equation maxwell equation

Periapsis shift in spherically symmetric spacetimes and effects of electric interactions

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第8期48卷 224-239页

作者： Qianchuan Wang Junji Jia school of Physics and Technology Wuhan UniversityWuhan 430072China Department of Astronomy&MOE Key Laboratory of Artificial Micro-and Nano-structures School of Physics and TechnologyWuhan UniversityWuhan 430072China

The periapsis shift of charged test particles in arbitrary static and spherically symmetric charged spacetimes are *** perturbative methods,the near-circular approximation and post-Newtonian methods,are developed and shown to be very accurate when the results are determined to high *** near-circular approximation method is more precise when eccentricity e of the orbit is small,whereas the post-Newtonian method is more effective when orbit semilatus rectum p is *** from these two methods are shown to agree when both e is small and p is *** results are then applied to the Reissner-Nordström spacetime,the Einstein-maxwell-dilation gravity,and a charged wormhole *** effects of various parameters on the periapsis shift,particularly that of the electrostatic interaction,are carefully *** periapsis shift data of the solar-Mercury are then used to constrain the charges of the Sun and Mercury,and the data of the Sgr A^(*)-S2 periapsis shift are used to determine,for the first time using this method,the constraints of the charges of Sgr A^(*)and S2.

关键词： periapsis shift orbital precession post-Newtonian approximation perturbative method

Two-temperature modeling of lamellar cathode arc

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2024年第6期26卷 120-139页

作者：李渊博刘兴叶韬 school of Materials Science and Engineering Lanzhou Jiaotong UniversityLanzhou 730070People’s Republic of China

A three-dimensional, two-temperature(2T) model of a lamellar cathode arc is constructed,drawing upon the conservation equations for mass, momentum, electron energy, and heavy particle energy, in addition to maxwell's equations. The model aims to elucidate how the physical properties of electrons and heavy particles affect heat transfer and fluid flow in a lamellar cathode arc. This is achieved by solving and comparing the fields of electron temperature,heavy particle temperature, fluid flow, current density, and Lorentz force distribution under varying welding currents. The results show that the guiding effect of the lamellar cathode on current density, the inertial drag effect of moving arc, and the attraction effect of Lorentz force at the lamellar cathode tip primarily govern the distribution of the arc's physical fields. The guiding effect localizes the current density to the front end of the lamellar cathode, particularly where the discharge gap is minimal. Both the inertial drag effect and the attraction effect of Lorentz force direct arc flow toward its periphery. Under the influence of the aforementioned factors, the physical fields of the lamellar cathode arc undergo expansion and shift counter to the arc's direction of motion. A reduction in welding current substantially weakens the guiding effect,causing the arc's physical fields to deviate further in the direction opposite to the arc motion. In comparison with a cylindrical cathode arc, the physical fields of the lamellar cathode arc are markedly expanded, leading to a reduction in current density, electron temperature, heavy particle temperature, cathode jet flow velocity, and Lorentz force.

关键词： numerical simulation two-temperature model welding arc

CAUCHY TYPE INTEGRALS AND A BOUNDARY VALUE PROBLEM IN A COMPLEX CLIFFORD ANALYSIS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2024年第1期44卷 369-385页

作者：曹南斌李尊凤杨贺菊乔玉英 school of Mathematics and Science Hebei GEO UniversityShijiazhuang050031China College of Science Hebei University of Science and TechnologyShijiazhuang050018China school of Mathematical Sciences Hebei Normal UniversityShijiazhuang050024China

Clifford analysis is an important branch of modern analysis;it has a very important theoretical significance and application value,and its conclusions can be applied to the maxwell equation,Yang-Mill field theory,quantum mechanics and value *** this paper,we first give the definition of a quasi-Cauchy type integral in complex Clifford analysis,and get the Plemelj formula for ***,we discuss the H?lder continuity for the Cauchy-type integral operators with values in a complex Clifford ***,we prove the existence of solutions for a class of linear boundary value problems and give the integral representation for the solution.

关键词： Clifford analysis Cauchy type integral Plemelj formula Holder continuous boundary value problems

Approximations to Isentropic Planar Magneto-Hydrodynamics Equations by Relaxed Euler-Type Systems

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2024年第3期45卷 413-440页

作者： Yachun LI Zhaoyang SHANG Chenmu WANG Liang ZHAO school of Mathematical Sciences CMA-ShanghaiMOE-LSC and SHL-MACShanghai Jiao Tong UniversityShanghai 200240China school of Finance Shanghai Lixin University of Accounting and FinanceShanghai 201209China school of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China school of Mathematical Sciences Harbin Engineering UniversityHarbin 150001China Mathematical Modelling&Data Analytics Center Oxford Suzhou Centre for Advanced ResearchSuzhou 215123JiangsuChina

In this paper, the authors consider an approximation to the isentropic planar Magneto-hydrodynamics(MHD for short) equations by a kind of relaxed Euler-type system. The approximation is based on the generalization of the maxwell law for nonNewtonian fluids together with the maxwell correction for the Ampe`re law, hence the approximate system becomes a first-order quasilinear symmetrizable hyperbolic systems with partial dissipation. They establish the global-in-time smooth solutions to the approximate Euler-type equations in a small neighbourhood of constant equilibrium states and obtain the global-in-time convergence towards the isentropic planar MHD equations. In addition, they also establish the global-in-time error estimates of the limit based on stream function techniques and energy estimates for error variables.

关键词： Planar MHD equations Relaxation limits Global convergence Stream function

A Fault Detection Method for Electric Vehicle Battery System Based on Bayesian Optimization SVDD Considering a Few Faulty Samples

在线全文

学校读者我要写书评

暂无评论

Energy Engineering 2024年第9期121卷 2543-2568页

作者： Miao Li Fanyong Cheng Jiong Yang maxwell Mensah Duodu Hao Tu school of Electronics and Electrical Engineering Anhui Polytechnic UniversityWuhu241000China

Accurate and reliable fault detection is essential for the safe operation of electric *** vector data description(SVDD)has been widely used in the field of fault ***,constructing the hypersphere boundary only describes the distribution of unlabeled samples,while the distribution of faulty samples cannot be effectively described and easilymisses detecting faulty data due to the imbalance of sample ***,selecting parameters is critical to the detection performance,and empirical parameterization is generally timeconsuming and laborious and may not result in finding the optimal ***,this paper proposes a semi-supervised data-driven method based on which the SVDD algorithm is improved and achieves excellent fault detection *** incorporating faulty samples into the underlying SVDD model,training deals better with the problem of missing detection of faulty samples caused by the imbalance in the distribution of abnormal samples,and the hypersphere boundary ismodified to classify the samplesmore *** Bayesian Optimization NSVDD(BO-NSVDD)model was constructed to quickly and accurately optimize hyperparameter *** the experiments,electric vehicle operation data with four common fault types are used to evaluate the performance with other five models,and the results show that the BO-NSVDD model presents superior detection performance for each type of fault data,especially in the imperceptible early and minor faults,which has seen very obvious ***,the strong robustness of the proposed method is verified by adding different intensities of noise in the dataset.

关键词： Fault detection vehicle battery system lithium batteries fault samples