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A Note on Finitely Generated Modules over a <i>PID</i>
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作者 Xinru Ma Heguo Liu Honglian Zhang 《Advances in Pure Mathematics》 2020年第12期699-705,共7页
In this note, we provide an effective proof of the fundamental structure theorem of finitely generated modules over a principal ideal domain, from which we find the minimality of decomposition for a finitely generated... In this note, we provide an effective proof of the fundamental structure theorem of finitely generated modules over a principal ideal domain, from which we find the minimality of decomposition for a finitely generated module over a principal ideal domain. 展开更多
关键词 finitely Generated module Principal Ideal Domain Cyclic module
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F-Decomposition of Noetherian Modules over Hyper-(Cyclic or Finite) Groups
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作者 秦应兵 段泽勇 《Journal of Southwest Jiaotong University(English Edition)》 2004年第1期83-86,共4页
Let Fbe a locally defined formation consisting of locally soluble groups, G a hyper-(cyclic or finite) locally soluble group and A a noetherian ZG-module with all irreducible ZG-factors being finite, G∈F, f(∞)f(p), ... Let Fbe a locally defined formation consisting of locally soluble groups, G a hyper-(cyclic or finite) locally soluble group and A a noetherian ZG-module with all irreducible ZG-factors being finite, G∈F, f(∞)f(p), f(p)≠ for each p∈π. The following conclutions are obtained: (1) if there exists a maximal submodule B of A such that A/B is F-central in G and B has no nonzero F-central ZG-factors, then A has an F-decomposition; (2) if there exists an irreducible F-central submodule B of A such that all ZG-composition factors of A/B are F-ecentric, then A has an F-decomposition. 展开更多
关键词 Noetherian module Hyper-(cyclic or finite) group F-decomposition
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The F-Decomposition of Artinian Modules over Hyper-(Cyclic or Finite)Groups
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作者 秦应兵 段泽勇 《Journal of Southwest Jiaotong University(English Edition)》 2002年第2期139-143,共5页
Let (?) be a formation locally defined by f(P), G ∈ (?) and A a ZG-module, where p ∈ π = { all primes and symbol ∞}. Then a p-main-factor U/V of G is said to be (?)-central in G if G/CG(U/V) ∈f(p). In this paper,... Let (?) be a formation locally defined by f(P), G ∈ (?) and A a ZG-module, where p ∈ π = { all primes and symbol ∞}. Then a p-main-factor U/V of G is said to be (?)-central in G if G/CG(U/V) ∈f(p). In this paper, we have proved that: let (?) be a locally defined formation consisting of locally soluble groups, G a hyper-(cyclic or finite) locally soluble group and A an artinian ZG-module with all irreducible ZG-factors of A being finite; if G ∈ (?), f(∞) ≡ f(p) . f(p)≠φ for each p ∈ π, A has an (?)-decomposition. 展开更多
关键词 (?)-decomposition artinian module hyper-(cyclic or finite) groups
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STIFFNESS ANALYSIS OF THE MAIN MODULE FOR PARALLEL MACHINE TOOLS BY FINITE ELEMENT ANALYSIS 被引量:2
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作者 周立华 王玉茹 +1 位作者 黄田 Modler K H 《Transactions of Tianjin University》 EI CAS 2001年第1期30-35,共6页
With the aid of commercial finite element analysis software package ANSYS,investigations are made on the contributions of main components to stiffness of the main module for parallel machine tools,and it is found that... With the aid of commercial finite element analysis software package ANSYS,investigations are made on the contributions of main components to stiffness of the main module for parallel machine tools,and it is found that the frame is the main contributor.Then,influences of constraints,strut length and working ways of the main module have also been investigated.It can be concluded that when one of the main planes of the frame without linear drive unit is constrained,the largest whole stiffness can be acquired.And,the stiffness is much better when the main module is used in a vertical machine tool instead of a horizontal one.Finally,the principle of stiffness variation is summarized when the mobile platform reaches various positions within its working space and when various loads are applied.These achievements have provided critical instructions for the design of the main module for parallel machine tools. 展开更多
关键词 parallel machine tool main module STIFFNESS finite element analysis
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Reducing Subspaces of Toeplitz Operators on N_φ-type Quotient Modules on the Torus
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作者 WU NAN Xu XIAN-MIN 《Communications in Mathematical Research》 CSCD 2009年第1期19-29,共11页
In this paper, we prove that the Toeplitz operator with finite Blaschke product symbol Sψ(z) on Nφ has at least m non-trivial minimal reducing subspaces, where m is the dimension of H^2(Гω)⊙φ(ω)H^2(Гω... In this paper, we prove that the Toeplitz operator with finite Blaschke product symbol Sψ(z) on Nφ has at least m non-trivial minimal reducing subspaces, where m is the dimension of H^2(Гω)⊙φ(ω)H^2(Гω). Moreover, the restriction of Sψ(z) on any of these minimal reducing subspaces is unitary equivalent to the Bergman shift Mz. 展开更多
关键词 modulE Nφ-type quotient module the analytic Toeplitz operator reducing subspace finite Blaschke product
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Some Equivalences and Dualities via Static Modules
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作者 Salah Al-Nofayee Syed Khalid Nauman 《Advances in Pure Mathematics》 2011年第6期359-362,共4页
For a ring A, an extension ring B, a fixed right A-module M, the endomorphism ring D formed by M, the endomorphism ring E formed by , and the endomorphism ring F formed by HomA (B,M), we present equivalences and duali... For a ring A, an extension ring B, a fixed right A-module M, the endomorphism ring D formed by M, the endomorphism ring E formed by , and the endomorphism ring F formed by HomA (B,M), we present equivalences and dualities between subcategories of B-modules which are finitely cogenerated injective as A-modules and E-modules and F-modules which are finitely generated projective as D-modules. 展开更多
关键词 STATIC modules finitely Cogenerated INJECTIVE modules finitely Generated PROJECTIVE modules
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F-Decomposition of Minimax Module over Hyper Finite Groups
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作者 秦应兵 盛晓玲 《Journal of Southwest Jiaotong University(English Edition)》 2008年第2期195-198,共4页
Let G be a hyper finite locally solvable group, A a minimax ZG-medule, a locally defined formation consisting of locally solvable groups, A has no nonzero infinite irreducible ZG-factors, and G ∈ . The following resu... Let G be a hyper finite locally solvable group, A a minimax ZG-medule, a locally defined formation consisting of locally solvable groups, A has no nonzero infinite irreducible ZG-factors, and G ∈ . The following results are proved: if A has a maximal submodule B such that A/B is , central in G and B has no nonzero central ZG-factors, then A has an decomposition; ifA has an irreducible central submodule B such that all ZG-composition factors of A/B are o^eccentric, then A has an decomposition. 展开更多
关键词 Minimax module Hyper finite group DECOMPOSITION
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Novel Electro-Optical Modulator Utilizing GeO_2-Doped Silica Waveguide 被引量:2
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作者 李九生 贾大功 《Transactions of Tianjin University》 EI CAS 2009年第3期222-224,共3页
In order to achieve a modulator with broad bandwidth and perfect impedance match,a novel electro-optical modulator based on GeO2-doped silica waveguides on silicon substrate is designed.The finite element model of the... In order to achieve a modulator with broad bandwidth and perfect impedance match,a novel electro-optical modulator based on GeO2-doped silica waveguides on silicon substrate is designed.The finite element model of the whole electro-optical modulator is established by means of ANSYS.With the finite element method analysis,the performance of the novel modulator is predicted.The simulation reveals that the designed modulator operates with a product of 3 dB optical bandwidth and modulating length of 226.59 GHz·cm,and a characteristic impedance of 51.6 Ω at 1 550 nm wavelength.Moreover,the calculated electrical reflected power of coplanar waveguide electrode is below-20 dB in the frequency ranging from 45 MHz to 65 GHz.Therefore,the designed modulator has wide modulation bandwidth and perfect impedance match. 展开更多
关键词 optical modulator GeO2-doped silica finite element method
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Wideband dipole logging based on segmen linear frequency modulation excitation 被引量:1
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作者 Cao Xue-Shen Chen Hao +3 位作者 Li Ping He Hong-Bin Zhou Yin-Qiu Wang XJu-Ming 《Applied Geophysics》 SCIE CSCD 2018年第2期197-207,362,共12页
A wideband dipole signal is required for dipole dispersion correction and nearborehole imaging. To obtain the broadband flexural wave dispersion, we use a nonlinear frequency modulation (NLFM) signal and propose a s... A wideband dipole signal is required for dipole dispersion correction and nearborehole imaging. To obtain the broadband flexural wave dispersion, we use a nonlinear frequency modulation (NLFM) signal and propose a segment linear frequency modulation (SLFM) signal as the dipole excitation signal to compensate for the excitation intensity. The signal-to-noise ratio (SNR) of the signal over the entire frequency band is increased. The finite-difference method is used to simulate the responses from a Ricker wavelet, a linear frequency modulation (LFM) signal, an NLFM signal, and an SLFM signal in two borehole models of a homogeneously hard formation and a radially stratified formation. The dispersion and radial tomography results at low SNR of the sound source signals are compared. Numerical modeling suggests that the energy of the flexural waves excited by the Ricker wavelet source is concentrated near the Airy phase. In this case, the dispersion is incomplete and information regarding the formation near or far from the borehole cannot be obtained. The LFM signal yields dispersion information near the Airy phase and the high-frequency range but not in the low-frequency range. Moreover, the information regarding the formation far from the borehole is not accurate. The NLFM signal extends the frequency range of the flexural waves by compensating for the excitation intensity and yields information regarding the formation information, but it is not easy to obtain. The SLFM signal yields the same results as the NLFM signal and is easier to implement. Consequently, the dipole detection range expands and the S-wave velocity calculation accuracy improves. 展开更多
关键词 Dipole acoustic logging DISPERSION frequency modulation finite difference
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Optical modulation of repaired damage site on fused silica produced by CO2 laser rapid ablation mitigation 被引量:1
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作者 Chao Tan Lin-Jie Zhao +5 位作者 Ming-Jun Chen Jian Cheng Zhao-Yang Yin Qi Liu Hao Yang Wei Liao 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第5期288-296,共9页
CO2 laser rapid ablation mitigation(RAM)of fused silica has been used in high-power laser systems owing to its advantages of high efficiency,and ease of implementing batch and automated repairing.In order to study the... CO2 laser rapid ablation mitigation(RAM)of fused silica has been used in high-power laser systems owing to its advantages of high efficiency,and ease of implementing batch and automated repairing.In order to study the effect of repaired morphology of RAM on laser modulation and to improve laser damage threshold of optics,an finite element method(FEM)mathematical model of 351 nm laser irradiating fused silica optics is developed based on Maxwell electromagnetic field equations,to explore the 3D near-field light intensity distribution inside optics with repaired site on its surface.The influences of the cone angle and the size of the repaired site on incident laser modulation are studied as well.The results have shown that for the repaired site with a cone angle of 73.3°,the light intensity distribution has obvious three-dimensional characteristics.The relative light intensity on z-section has a circularly distribution,and the radius of the annular intensification zone increases with the decrease of z.While the distribution of maximum relative light intensity on y-section is parabolical with the increase of y.As the cone angle of the repaired site decreases,the effect of the repaired surface on light modulation becomes stronger,leading to a weak resistance to laser damage.Moreover,the large size repaired site would also reduce the laser damage threshold.Therefore,a repaired site with a larger cone angle and smaller size is preferred in practical CO2 laser repairing of surface damage.This work will provide theoretical guidance for the design of repaired surface topography,as well as the improvement of RAM process. 展开更多
关键词 fused silica laser repaired surface optical modulation finite element method(FEM)
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Fast Calculation of Electromagnetic Forces in IPMSMs Under PWM VSI Supply Based on Small-Signal Time-Harmonic Finite Element Method 被引量:3
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作者 Sa Zhu Jianbo Lu Feng Zeng 《CES Transactions on Electrical Machines and Systems》 CSCD 2022年第1期67-76,共10页
This paper introduces a novel method for fast calculating the electromagnetic forces in interior permanent magnet synchronous machines(IPMSMs)under pulse width modulation(PWM)voltage source inverter(VSI)supply based o... This paper introduces a novel method for fast calculating the electromagnetic forces in interior permanent magnet synchronous machines(IPMSMs)under pulse width modulation(PWM)voltage source inverter(VSI)supply based on the small-signal time-harmonic finite element analysis(THFEA),which has been successfully utilized for fast calculating the PWMinduced losses in silicon steel sheets and permanent magnets.Based on the small-signal THFEA,the functional relationships between high-frequency harmonic voltages(HFHVs)and corresponding airgap flux densities are established,which are used for calculating the flux density spectra caused by each HFHV in the PWM voltage spectra.Then,the superposition principle is applied for calculating the flux density spectra caused by fundamental currents and all HFHVs,which are converted to the electromagnetic force spectra at last.The relative errors between the force density spectra calculated with the proposed method and those obtained from traditional time-stepping finite element analysis(TSFEA)using PWM voltages as input are within 3.1%,while the proposed method is 24 times faster than the traditional TSFEA. 展开更多
关键词 Time-harmonic finite element analysis(THFEA) Interior permanent magnet synchronous machines(IPMSMs) Electromagnetic forces Pulse width modulation Vibration and acoustic noise
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Numerical simulation of jet breakup due to amplitude-modulated (A-M) disturbance 被引量:3
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作者 罗俊 齐乐华 +2 位作者 李莉 杨方 蒋小珊 《中国有色金属学会会刊:英文版》 EI CSCD 2008年第3期686-690,共5页
In order to characterize the mechanics of jet breakup, the finite volume formulations were employed to solve the Navier-Stokes equations and continuity equation of jet. The volume of fluid(VOF) method was used to trac... In order to characterize the mechanics of jet breakup, the finite volume formulations were employed to solve the Navier-Stokes equations and continuity equation of jet. The volume of fluid(VOF) method was used to track the free surface of jet. The spray process of the molten Pb63Sn37 alloy was simulated based on the mathematical model by means of FLUENT code. The configuration of jets generated in different disturbance ratios and modulation ratios was obtained. The theoretical results show that the droplets merge together by the number of disturbance ratio N, which agrees with the corresponding picture captured in the experiment. In addition, the droplet streams broken at non-optimal frequency are also uniform according to simulation results, which proves that the A-M disturbance can increase the width of the uniform droplet generating frequency. 展开更多
关键词 振幅调制 喷射 统一滴流 物理研究
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A compact electro-absorption modulator based on graphene photonic crystal fiber
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作者 Guangwei Fu Ying Wang +5 位作者 Bilin Wang Kaili Yang Xiaoyu Wang Xinghu Fu Wa Jin Weihong Bi 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第3期238-244,共7页
A compact electro-absorption modulator based on graphene photonic crystal fiber is proposed. To enhance the graphene–light interaction efficiency, the innermost six air-holes of photonic crystal fiber are replaced by... A compact electro-absorption modulator based on graphene photonic crystal fiber is proposed. To enhance the graphene–light interaction efficiency, the innermost six air-holes of photonic crystal fiber are replaced by two large semicircular holes, and monolayer graphene is deposited on the two large semicircular holes. By optimizing the structure parameters, a strong graphene–light interaction is obtained. Moreover, the switch on–off point of the modulator is unchangeable,which is only related to the frequency of the incident light. The influence factors of this composite structure have been analyzed. The proposed modulator is compared with other graphene-based modulators, and the results show that it is filled without dielectric spacer. There are some excellent performances, such as an extinction ratio 7 dB of y-polarization mode,3-dB modulation bandwidth of 70 GHz with small footprint of 205 μm, and a consumption of energy per bit 59 pJ/bit. 展开更多
关键词 GRAPHENE electro-absorption modulATOR finitE ELEMENT method
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The Primary Radical of a Submodule
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作者 Lamis J. M. Abulebda 《Advances in Pure Mathematics》 2012年第5期344-348,共5页
In this paper we introduced a definition for the primary radical of a submodule with some of its basic properties. We also define the P-radical submodule and review some results about it. We find a method to character... In this paper we introduced a definition for the primary radical of a submodule with some of its basic properties. We also define the P-radical submodule and review some results about it. We find a method to characterize the primary radical of a finitely generated submodule of a free module. 展开更多
关键词 PRIMARY SUBmodulE PRIME RADICAL of a SUBmodulE RADICAL SUBmodulE Free modulE NOETHERIAN modulE finitely Generated SUBmodulE
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Splitting Extensions of Abelian by Hyper-(cyclic or finite) Groups (Ⅱ)
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作者 秦应兵 《Journal of Southwest Jiaotong University(English Edition)》 2006年第3期291-294,共4页
Let F be a locally defined formation consisting of locally solvable groups, G a hyper-( cyclic or finite) locally solvable group and A a noetherian ZG-module with all irreducible ZG-factors being finite. The followi... Let F be a locally defined formation consisting of locally solvable groups, G a hyper-( cyclic or finite) locally solvable group and A a noetherian ZG-module with all irreducible ZG-factors being finite. The following conclusion is obtained: if G∈F, f( ∞ ) include f(p), f(p) ≠φ for each p∈π, and A has no nonzero F central ZG- images, then any extension E of A by G splits conjugately over A, and A has no nonzero F central ZG-factors. 展开更多
关键词 Noetherian module Abelian group Hyper-(cyclic or finite) group Splitting conjugacy Extension
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On the Decomposition of Hopf Module Coalgebra
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作者 焦争鸣 王栓宏 赵文正 《Chinese Quarterly Journal of Mathematics》 CSCD 1998年第2期36-40, ,共5页
In this paper, the module coradical is introduced. From this, we show that any Hopf module coalgebra which is local finite can be uniquely decomposed into a direct sum of its indecomposable components. This result is ... In this paper, the module coradical is introduced. From this, we show that any Hopf module coalgebra which is local finite can be uniquely decomposed into a direct sum of its indecomposable components. This result is a generalization of the decompostion theorem of coalgebra. 展开更多
关键词 Hopf module coalgebra local finite Hopf module coalgebra Hopf algebra
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Study on incident laser modulation using surface micro-defects on KH_2PO_4 crystal
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作者 陈明君 程健 +7 位作者 李明全 肖勇 曲遵世 王勇刚 刘杰 郑丽和 苏良碧 徐军 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期249-256,共8页
KH2PO4 crystal is a crucial optical component of inertial confinement fusion. Modulation of an incident laser by surface micro-defects will induce the growth of surface damage, which largely restricts the enhancement ... KH2PO4 crystal is a crucial optical component of inertial confinement fusion. Modulation of an incident laser by surface micro-defects will induce the growth of surface damage, which largely restricts the enhancement of the laser induced damage threshold. The modulation of an incident laser by using different kinds of surface defects are simulated by employing the three-dimensional finite-difference time-domain method. The results indicate that after the modulation of surface defects, the light intensity distribution inside the crystal is badly distorted, with the light intensity enhanced symmetrically. The relations between modulation properties and defect geometries (e.g., width, morphology, and depth of defects) are quite different for different defects. The modulation action is most obvious when the width of surface defects reaches 1.064 p-m. For defects with smooth morphology, such as spherical pits, the degree of modulation is the smallest and the light intensity distribution seems relatively uniform. The degree of modulation increases rapidly with the increase of the depth of surface defects and becomes stable when the depth reaches a critical value. The critical depth is 1.064 μm for cuboid pits and radial cracks, while for ellipsoidal pits the value depends on both the width and the length of the defects. 展开更多
关键词 KH2PO4 crystal surface defects modulation degree three-dimensional finite-differencetime-domain
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Selforthogonal modules with finite injective dimension 被引量:10
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作者 黄兆泳 《Science China Mathematics》 SCIE 2000年第11期1174-1181,共8页
The category consisting of finitely generated modules which are left orthogonal with a cotilting bimodule is shown to be functorially finite. The notion of left orthogonal dimension is introduced , and then a necessar... The category consisting of finitely generated modules which are left orthogonal with a cotilting bimodule is shown to be functorially finite. The notion of left orthogonal dimension is introduced , and then a necessary and sufficient condition of selforthogonal modules having finite injective dimension and a characterization of cotilting modules are given. 展开更多
关键词 INJECTIVE DIMENSION self ORTHOGONAL modules cotilting (bi) modules homologically finitE subcate-gories LEFT ORTHOGONAL dimension.
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中心距误差对小模数齿轮接触与弯曲强度的影响
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作者 胡波 申朋 +3 位作者 刘辉华 尹来容 汪红兵 周长江 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第10期106-115,共10页
为探究小模数齿轮中心距误差对轮齿强度的影响,以及标准GB/T 3480—2021对含中心距误差小模数齿轮强度设计的适用性,推导了含中心距误差的重合度系数、齿廓系数与应力修正系数计算公式,建立了含中心距误差的小模数齿轮有限元接触模型,... 为探究小模数齿轮中心距误差对轮齿强度的影响,以及标准GB/T 3480—2021对含中心距误差小模数齿轮强度设计的适用性,推导了含中心距误差的重合度系数、齿廓系数与应力修正系数计算公式,建立了含中心距误差的小模数齿轮有限元接触模型,提出有限元接触模型网格密度的验证方法.对2种计算方法得到的不同中心距误差下接触与弯曲应力进行了对比研究,结果表明,接触区域齿廓有限单元宽度不超过Hertz接触半宽的1/3时,齿轮有限元接触计算精度较高;采用标准GB/T 3480—2021校核含中心距误差的小模数齿轮强度,将产生冗余设计;当中心距误差达到1.33%时,接触应力幅值的最大变化为4.23%,而弯曲应力幅值的最大变化达到了16.25%,中心距误差对小模数齿轮弯曲应力的影响比接触应力更为显著. 展开更多
关键词 齿轮 有限元法 小模数 中心距误差 齿轮强度
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计及IGBT模块键合线与芯片焊料层老化的热网络法结温计算 被引量:1
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作者 何梦宇 许智亮 +2 位作者 谢望玉 葛兴来 王为介 《铁道机车车辆》 北大核心 2024年第4期28-35,共8页
文中提出一种计及IGBT模块键合线与芯片焊料层老化的热网络法结温计算,基于Simulink对短时间尺度下损耗与结温的相互依赖关系进行更新,并分别通过双脉冲测试及有限元仿真修正长时间尺度下键合线与芯片焊料层老化对IGBT结温计算的影响,... 文中提出一种计及IGBT模块键合线与芯片焊料层老化的热网络法结温计算,基于Simulink对短时间尺度下损耗与结温的相互依赖关系进行更新,并分别通过双脉冲测试及有限元仿真修正长时间尺度下键合线与芯片焊料层老化对IGBT结温计算的影响,在此基础上,根据芯片焊料层不同老化状态下键合线的应力特征,实现两种老化模式的相互关联,较为准确地计算IGBT结温。最终利用试验平台与传统结温计算方法进行对比验证了所提结温计算方法的准确性。该结温计算方法有助于在实际运行工况及IGBT模块老化状态下精确计算结温。 展开更多
关键词 IGBT结温计算 热网络模型法 模块老化 双脉冲试验 有限元仿真
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