巧解直流电路动态分析问题

直流电路动态分析是依据全电路欧姆定律,串并联电路的特点进行求解.学生在解决这类问题时往往有困难.现将笔者在教学中针对此类问题的点滴体会与方法提出来与大家共享、探讨.针对此类问题的处理方法可用四个字概括即"串反并同".若用"串反并同"的规律解决此类问题可使问题简单化."串反并同"的含义是:看要研究的物理量与变化电阻阻值的关系,如果是串联,其变     

光纤法珀应变传感器串并联混合复用的离散腔长变换解调研究

光纤法珀传感器复用的输出信号复杂,解调相当困难.为实现其串并联混合结构复用,根据光纤法珀应变传感器的双光干涉原理,阐述了传感器串并联混合复用的输出信号特征,分析了信号中各项成分对离散腔长变换方法解调结果的影响,并进行了计算机仿真.最后搭建实验平台,进行了四个传感器串并联混合复用的实验研究,证明该方案可行,解调准确度1 μm.     

例析初中电学习题的分析方法

1问题的提出 串并联电路中的电流规律、电压规律和电阻规律反映出同一电路中同一个电学量之间的关系;欧姆定律揭示了同一段电路中不同电学量之间的关系．因此综合运用串并联电路的规律和欧姆定律是分析解决简单电路问题的必由之路．在教学实践中,     

物理量单位的智能导出算法及其应用

推导物理量的单位是物理作业中不可缺少的重要环节。提出一种物理量单位的智能导出算法,即计算机根据物理量的运算式自动推导出待求物理量的单位。实验结果表明,物理量单位导出及换算算法的结果正确,对算术运算式中的物理量单位导出及换算的正确率为100%,且物理量数值的运算正确。     

弹簧串并联特点及应用

讨论了弹簧在进行串并联以后性质的变化情况,通过对实际问题应用的分析,使学生明白弹簧的串并联有时只是形式上的串并联,在具体分析题目的时候一定要根据实际情况,灵活处理,切忌乱套公式.本课题的研究可以较好地培养学生分析问题、解决问题的能力.     

探究弹簧劲度系数实验改进与创新

利用自制实验装置探究胡克定律以及弹簧串并联劲度系数关系,新实验装置能直接在坐标纸上绘出弹簧弹力与弹簧伸长量之间的对应关系、弹簧串并联劲度系数关系等。     

物理量单位中物理文化探索

介绍了基本物理量的发展史、物理量国际单位制（SI）在建立过程中体现的物理文化内涵以及在物理量单位中引人人文元素的发展与传播     

用节点法简画电路图

电路理论是一门研究网络综合或设计的基础工程学科,实践证明只要电路模型取得适当,所得的结果与对应的实际电路中测量所得结果基本是一致的,反之则会造成很大误差,对电路进行分析和计算的时候,对一些电路串并联关系比较复杂,或者说元件间的串并联关     

辨析物理量中正负号的含义

在物理学中,一些物理量的正负号问题一直困扰着学生．因此物理量的正负也就成为物理教学中的难点．在教学中关键在于理解物理量正负的本质．     

LRC串并联谐振电路的品质因数与电容和电感关系的实验研究

在LRC串并联谐振电路中,回路的谐振特性通常由回路中的品质因数决定,而回路中的品质因数又与回路中的电容、电感、电阻有关。本文通过实验的方法,对回路的品质因数与电容和电感的关系进行了研究。得出了在串并联谐振电路中电容和电感的合理取值范围。所得结论将为今后LRC谐振回路的选择和设计提供一定的参考。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.