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1.
非晶合金铁心变压器振动噪声分析与研究   总被引:1,自引:0,他引:1  
通过对一台非晶合金铁心干式配电变压器振动噪声的特性测试分析及力学建模与分析,对变压器噪声源进行了识别,并得出了降噪的措施。  相似文献
2.
In this paper, electrical characteristics of metal-oxide-semiconductor field effect transistor (MOSFET) with silicon/gallium-arsenic (Si/GaAs) stacked film are numerically studied. By calculating several important device characteristics, such as the on-state current, the subthreshold swing, the drain induced barrier lowering, the threshold voltage, the threshold voltage roll-off, and the output resistance, a 50 nm Si/GaAs MOSFET is simulated with respect to different thicknesses of Si/GaAs film. Compared with the results of pure Si MOSFET, Si/GaAs MOSFET shows promising characteristics after properly selecting the thickness of Si/GaAs film. Among Si, germanium (Ge), and Si/Ge MOSFETs, Si/GaAs MOSFET relatively exhibits a higher driving capability due to higher carrier mobility within the Si/GaAs film. However, quantitatively accurate estimation of device characteristics will depend upon more precise calculation of band structure of the stacked film.  相似文献
3.
In this paper, we computationally investigate fluctuations of the threshold voltage introduced by random dopants in nanoscale double gate metal-oxide-semiconductor field effect transistors (DG MOSFETs). To calculate variance of the threshold voltage of nanoscale DG MOSFETs, a quantum correction model is numerically solved with the perturbation and the monotone iterative techniques. Fluctuations of the threshold voltage resulting from the random dopant, the gate oxide thickness, the channel film thickness, the gate channel length, and the device width are calculated. Quantum mechanical and classical results have similar prediction on fluctuations of the threshold voltage with respect to different designing parameters including dimension of device geometry as well as the channel doping. Fluctuation increases when the channel doping, the channel film thickness, and/or the gate oxide thickness increase. On the other hand, it decreases when the channel length and/or the device width increase. Calculations of the quantum correction model are quantitatively higher than that of the classical estimation according to different quantum confinement effects in nanoscale DG MOSFETs. Due to good channel controllability, DG MOSFETs possess relatively lower fluctuation, compared with the fluctuation of single gate MOSFETs (less than a half of the fluctuation[-11pc] of SG MOSFETs). To reduce fluctuations of the threshold voltage, epitaxial layers on both sides of channel with different epitaxial doping are introduced. For a certain thickness of epitaxial layers, the fluctuation of the threshold voltage decreases when epitaxial doping decreases. In contrast to conventional quantum Monte Carlo approach and small signal analysis of the Schr?dinger-Poisson equations, this computationally efficient approach shows acceptable accuracy and is ready for industrial technology computer-aided design application.  相似文献
4.
We study theoretically the electron energy states for three-dimensional (3D) nano-scopic semiconductor quantum rings. In this study, the model formulation includes: (i) the effective one-band Hamiltonian approximation, (ii) the position and energy dependent quasi-particle effective mass approximation, (iii) the finite hard wall confinement potential, and (iv) the Ben Daniel-Duke boundary conditions. To calculate the energy levels, the 3D model is solved by nonlinear iterative algorithm to obtain self-consistent solutions. The model and solution method provide a novel way to calculate the energy levels of nano-scopic semiconductor quantum ring and are useful to clarify the principal dependencies of quantum ring energy states on material band parameter, ring size and shape. We find the energy levels strongly depend on the radial cross section shapes of quantum rings. The dependence of energy states on shapes of 3D quantum ring reveals a significant difference from results derived on basis of 2D approaches.  相似文献
5.
In this paper, electrical characteristics of 25 nm strained fin-typed field effect transistors (FinFETs) with oxide-nitride-stacked-capping layer are numerically studied. The FinFETs are fabricated on two different wafers, one is bulk silicon and the other is silicon-on-insulator (SOI) substrate. A three-dimensional device simulation is performed by solving a set of density-gradient-hydrodynamic equations to study device performance including, such as the drain current characteristics (the ID-VG and ID-VD curves), the drain-induced barrier height lowering, and the subthreshold swing. Comparison between the strained bulk and SOI FinFETs shows that the strained bulk FinFET is promising for emerging multiple-gate nanodevice era according to the manufacturability point of view.  相似文献
6.
In this paper, we utilize an evolutionary technique for inverse doping profile problems of the 65 nm complementary metal oxide semiconductor (CMOS) devices. The approach mainly bases upon the process simulation, device simulation, evolutionary strategy, and empirical knowledge. For a set of given measured I-V curves of the 65 nm CMOS, a developed prototype performs the optimization task to automatically calibrate and inversely search out, for example the doping recipe and device physical model parameters. The simulation-optimization-coupled methodology is complicated theoretically, but our preliminary results imply that it may benefit the development of fabrication technology and can be used for the performance diagnosis, in particular, for sub-65 nm devices.  相似文献
7.
The electrical properties of BaO-Nd2O3-Sm2O3-TiO2 ceramics doped with low loss glass or low melting point oxide B2O3 are evaluated by impedance spectroscopy. Glass or B2O3 is doped as liquid phase sintering aid. Doping of glass/B2O3 enhances both the growth in the longitudinal direction of the columnar crystal and the preferred orientation of (002). The grain size increases and grain boundary decreases with the increase of dopant. Both the grain and grain-boundary resistivities decrease with the increase of dopant. The grain boundary activation energy for charge transport is larger than that of the grain activation energy. Possible mechanisms for the electrical behavior of the liquid-phase sintered BaO-Nd2O3-Sm2O3-TiO2 ceramics are proposed and discussed.  相似文献
8.
Contents  In this paper, first the apportioning of null-space-vector duty ratio between two null-space-vectors for the conventional three-phase voltage source sinusoidal pulse width modulation inverter is derived. To achieve clean sinusoidal input current, adjustable power factor and bidirectional power flow and step-up/down output DC voltage, analytic duty cycle control laws based on the derived null-space-vector duty ratio are then derived. As a result, the popularly used state-space technique can be extended easily for modeling a process that allows to obtain any kind of the desired transfer functions and dynamic responses. Based on these dynamic responses obtained the regulators of closed loop control system can be designed or adjusted properly. Finally, some simulated and measured results are presented for demonstration. Received: 16 September 2000  相似文献
9.
提出了无刷双馈电机的时步有限元数学模型,用该模型分析研究了该类电机的饱和效应,分析计算了在考虑饱和的情况下的电机的铁芯损耗,并提出了无刷双馈电机的饱和系数的概念,将饱和系数引入到无刷双馈电机的数学模型中,可以获得考虑饱和效应的更为精确的无刷双馈电机的数学模型。  相似文献
10.
无刷双馈电机通过改变控制绕组上的供电方式,可以实现自起动、同步、异步、双馈等多种运行方式。文章分析了无刷双馈电机在控制绕组上外加的电压或电流的最大值发生变化时,电机的稳定运行范围的变化规律,为设计、运行和选用无刷双馈电机提供了依据。  相似文献
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