关于电容电压和电感电流跃变的讨论

本文针对电路教科书指出的有两种情况可能会出现冲激电流和冲激电压的情况,通过举例说明,电容电压和电感电流的跃变可以在多种情况下发生。笔者还讨论了电容电压和电感电流跃变与换路定律之间的关系,即电容电压和电感电流跃变是对实际电路理想化建模的结果。本文通过实例指出正确理解电容电压和电感电流的跃变,有助于简化电路的分析。     

全电感割集网络初始电流的矩阵算法

在电路瞬态分析中会遇到换路后形成全电感割集的情况,由于此时换路定则失效,给确定复杂电路初始值带来困难.本文依据磁链守恒、基尔霍夫电流定律及电感元件伏安关系,导出了计算全电感剖集网络初始电流的矩阵算法,并给出实现该算法的MATLAB通用程序,使得计算大规模全电感割集网络初始值变得轻而易举.     

换路定律的延拓

传统的换路定律要求电容端电压和电感中电流为有限值。本文基于电路发生换路前后瞬间电荷与磁通守恒原理，导出了与传统不同的方法来确定换路后电路的初始条件。该方法的主要点在于对电路中出现冲激变量的有效处理能力，在有限电荷和磁通的假设下，将原电路分解成不同的子电路并分别计算，从而得到最后的解。此方法同时适用于线性与非线性电路。     

初始值不能由0_ 等效电路求出时的求法

求动态电路电压和电流响应，需要知道其初始值，初始值一般由0十等效电路求得。但是，有些电路例外。《电工教学》第17卷第4湖中沈传庄老师的《0十等效电路不一定能求解所有初始电压和电流》一文（以下简称“0十文”）就论述了这个问题。这些电路中的一类为：凡是动态电路中存在由电感元件和电流源元件组成的割集，或者存在纯由电感元件组成的割集，则由0十等效电路求不出割集中各元件的初始电压；另一类为：凡是动态电路中存在由电容元件和电压源元件组成的回路，或者存在纯由电容元件组成的回路，则由0十等效电路求不出回路中各元件的初始…     

对动态奇异电路的初始值问题的研究

在动态电路的时域分析中,若要解出描述电路的微分方程或状态方程,首先必须知道电路的初始状态。可是对含有纯电容回路和纯电感割集的奇异电路,在“换路”瞬间其初始值有可能发生跃变现象,不能用换路定则来求解。文章对此类电路中的初始值进行了详细的分析。通过深入探讨,给出了奇异电路中电容电压和电感电流初始值的确定方法,并给出了几个应用实例。     

对互感电路初值问题的探讨

在动态网络中,换路定则告诉我们:当电感电压u_L有限时,电感电流i_L连续,即i_L(O_+)=i_L(0_-);当电容电流i_C有限时,电容电压u_c连续,即u_c(0_+)=u_c(0-)对于含有互感的电路,换路定则又将如何?在许多教科书中对此均未涉及,本文就对这个问题作一探讨。     

无线电基础知识讲座 无线电三大基本元件组成的电路(下)

6 电感和电容组成的串、并联电路6.1 电感与电容串联电路电感和电容组成的串联电路图6-1所示。因电路中只有电感和电容,所以,只存在感抗和容抗。其复阻抗为:Z=R+jX_L-jX_C。因R=0,所以 Z=jXL-jXc=j(X_L-X_C)。其模值:z=|X_L-X_C|。我们在介绍元件时已经谈过,电感的感抗是图6-1电感电容由于导线中的电流产生磁力线,串联电路磁力线反过来又切割导线而产生反电动势抵抗原电流变化的一种作用;容抗是由于静电感应使电容两     

对初始电荷不同的两电容串、并联后的暂态分析

本文对初始电荷不同的两电容串、并联后其电压在线性动态电路中的暂态问题进行了分析,并针对因未明确"换路定理"的适用条件而犯错的几种情况进行了讨论,给出了换路定理的适用条件,通过举例说明此类问题的具体解决方法。     

关于画零状态动态电路在冲激信号源作用时刻等效电路的探讨

关于如何画出零状态动态电路在冲激信号源作用时刻的等效电路的问题,在国内出版的一些教材中,有所涉及。但是,在有些教材中的论述是不妥的,错误地将换路定律用于电容C在冲激电流作用下的u_c(t)和电感L在冲激电压作用下的i_L(t).例如,图1所示RC并联电路的冲激响应分析图。     

关于线性电容之静态电容和动态电容作用的研究

在对由两个初始电压不为零的电容及一个电阻串联构成的一阶电路分析时,发现研究动态电路的过渡过程时要区分静态电容和动态电容,否则有可能会导致分析计算的错误。计算线性电容储存能量公式中的电容是电容元件的静态电容,初始电荷不等的两个电容元件串联时,其等效静态电容无法确定。一阶RC电路的时间常数中的电容是电容元件的动态电容或电容元件串联、并联的等效动态电容。在分析一阶电路的动态过程时要特别注意这些问题,希望引起从事电路教学工作的同行注意。     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-