MATLAB在大学物理实验常用数据处理中的应用

大学物理实验的常用数据处理方法有作图法、逐差法、最小二乘法等。本文用实例介绍了MATLAB在这几种常用数据处理方法中的应用。MATLAB处理实验数据简单方便、准确度高,提高了学生的实验数据处理速度和质量。     

作图法在实验数据处理中的作用

作图法的优点是简便、形象、直观，有取平均值的效果，便于发现测量错误．利用作图法处理实验数据，有利于进一步研究实验结果，求出某些物理量，建立关系式等．在中学物理实验中，作图法在部分实验数据处理中有着广泛的应用。     

Origin软件在大学物理实验数据处理中的应用

本文以一实例详细介绍了Origin软件对大学物理实验数据处理的方法,其在处理量大繁多的实验数据时具有强大的功能,与传统的手工处理方法相比,利用该软件可以提高作图精度和减少数据处理误差.     

巧用Excel处理大学物理实验数据

以霍尔元件测量磁场为例,介绍了用Excel软件对实验数据进行分析处理的一般过程.结果表明利用Excel处理物理实验数据能大大减轻学生繁杂的数据计算及处理步骤,有效避免了手工处理所带来的误差,并且能满足一般的实验作图要求,适宜在大学物理实验数据处理方面推广应用.     

基于不确定度处理的导热系数实验挖掘

在计算机普及和大物实验智能化的时代背景下,许多理工院校特别是普通工科院校中对实验数据的处理要求逐渐简化,甚至已不再有不确定的数据处理要求。部分学有遗力或感兴趣的学生希望有更深入的数据处理与分析,但缺乏比较有可操作性的实例参考,目前导热系数的数据处理相关文献尚无不确定度处理的报道。特别是不确定处理,成了学生难以触及触摸的禁区。针对这样的现状,我们提供了方程回归法、作图法和逐差法这三种有效的数据处理方法,并首次详细给出了不确定度处理过程。基于不确定处理结果,我们进行了有效的误差分析并针对性地提出了实验的操作建议,具有一定的参考价值。     

多种方法结合处理密立根油滴实验数据

密立根油滴实验是大学物理实验比较经典的实验,用作图法处理数据求基本电荷量是比较直观的一种处理数据的方法,只要确定q1=ne中n值就可以求出基本电荷量,因此对第一个电荷的精度要求很高。在做实验时难免会存在误差,为了减小因数据处理方法带来的误差,在此提出在作图法的基础上增加分组预处理数据后再用最小二乘法处理数据。直接用作图法处理数据求出基本电荷量的相对误差为6.2%。作图法和分组法结合结果相对误差为2.6%。作图法、分组法和最小二乘法相结合处理数据相对误差为1.8%。本文提出的数据处理的方法减小了误差,可以将其应用到实际教学中。     

非良导体导热系数实验数据处理方法比较

利用作图法、逐差法以及最小二乘法三种方法对非良导体导热系数实验所测量的数据进行了处理。通过对三种数据处理方法进行分析、比较,发现逐差法是该实验中数据处理的最佳方法。     

霍尔效应实验及数据处理

本文介绍了霍尔效应实验方法，系统地研究了数据处理的方法，即平均值法、作图法、直线拟合法，并比较这三种方法的异同。     

利用Excel处理稳态法测定导热系数的实验数据

基于稳态法测定导热系数实验,为了求得更为精确的散热铜盘在稳态点的冷却率,用Excel软件处理实验数据,拟合出散热铜盘温度和时间的高阶曲线,并得出稳态点的切线方程,从而求得冷却率及导热系数。减少了手工作图求解切线方程所带来的误差,提高了数据处理的效率和实验结果的准确性。     

作图法处理数据及其不确定度的评定

作图法处理数据是大学物理实验训练内容之一。本文强调了作图法的作用与优点,较详尽的说明了作图法的具体规范以及如何用图线上的直线与斜率导出物理量的方法,最后给出作图法处理数据不确定度的一般方法。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.