T r a c k e r视频分析软件在 “ 研究抛体运动规律”实验中的应用

在“ 研究抛体运动规律”实验中, 用手机拍摄平抛运动物体视频, 利用视频分析软件 T r a c k e r捕捉运动 中物体的位置及时间. 数据处理结果表明这种方法能够方便、 准确地获得平抛运动规律, 以及水平运动速度和竖直 方向的重力加速度     

基于Algodoo对不同情况的斜抛运动研究

基于斜抛运动规律,结合相应问题,利用Algodoo仿真实验平台深入研究在有和没有空气阻力情况下斜抛运动的轨迹、射程、射高、速度和加速度之间的差异,同时在考虑空气阻力的情况下对影响斜抛运动射程、射高的因素进行探究,并提出了将所得研究结果融入"斜抛运动"教学的相关建议.     

考虑空气阻力与速度平方成正比的斜抛运动

物体在空气中运动, 不可避免地受到空气阻力, 有时空气阻力的作用必须加以考虑, 例如炮弹射击. 物 体速度较大, 阻力f∝v 2. 考虑阻力f= -k v 2, 建立运动模型, 运用 MAT LA B软件数值求解, 研究物体的运动性 质、 轨迹、 射程和射高, 并与无空气阻力的斜抛运动对比     

基于实际效果分解法分析斜抛运动问题

在分析斜抛运动问题时,可依据按实际效果分解的方法沿着初速度方向和竖直方向将斜抛运动分解为两个方向的直线运动,并结合几何关系予以定量解析.从斜面斜抛运动出发,通过对问题实例的分析,凸显按实际效果分解斜抛运动的巧妙运用,以期对解决斜抛运动的相关问题提供一定的参考.     

例谈Algodoo软件在高中物理教学中的应用

以“斜抛运动”“布朗运动”“机械能守恒定律”为例,使用Algodoo虚拟仿真软件对投篮、大小颗粒在液体中的运动和过山车等3个物理情境进行模拟仿真,并示范如何将模拟仿真出来的物理情境分别应用在相应的课题教学中.     

关于斜抛运动的分析

对斜抛运动的方程进行了较详细的分析，从而得到了关于斜抛物体的若干运动特性。     

在气垫导轨上演示运动独立性原理

从平抛运动出发,在气垫导轨上演示小球自由下落和竖直上抛实验,将平抛和斜抛运动分成垂直和水平2个方向的运动.本实验演示效果较好,实验现象直观,宜于学生理解运动的独立性原理.     

斜抛运动演示器的制作

中师(高中)物理教材中,在研究斜抛运动的射高和射程跟抛射角和初速度的关系时,给出了一个用水嘴喷水的实验,这个实验很不方便.今设计制作了一台斜抛运动演示器,如图1所示,便于操作,效果好.下面介绍制作方法和使用方法.     

基于Tracker软件的学生居家探究实验——以蹦极运动为例

本文设计了基于Tracker软件模拟蹦极运动的学生居家探究实验,用橡皮筋和橘子来模拟蹦极运动,再用Tracker软件分析所录制的蹦极运动视频,得到橘子在竖直方向上运动的位移、速度和加速度随时间变化的图像,通过与弹簧振子的运动过程进行对比,进而分析二者的运动规律并绘制出两者的机械能图像,是学生基于Tracker软件对真实生活情境进行自主研究性学习的一次探索.     

基于Virtools的平抛运动仿真实验的设计与实现

三维仿真实验能够模拟逼真的实验场景和现象帮助学生理解复杂的物理原理,并激发学生的学习兴趣.但是,专业的研究团队制作的商业仿真实验软件售价太高,无法在课堂推广.本研究小组将以Virtools仿真软件为开发平台制作出一系列的虚拟仿真实验.本论文以平抛运动实验为例,介绍了平抛运动仿真实验的制作过程,主要包括分析与设计、模型的构建、交互功能设计和作品发布四个步骤.在论文的最后部分,介绍了仿真实验在课堂实践的成效并对物理仿真实验的发展前景进行了展望.     

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.