运用引导性工作单评价科学探究能力的实证研究

以单摆为案例,运用引导性工作单评价185名初三学生的科学探究能力,结果发现,一些学生倾向于用最简单、省事的方式来做科学探究;一些学生能做不能说,不注重证据呈现;一些学生的前后探究步骤不相关等.     

試談指导学生閱讀教科书的問題

一阅读教科书是学生掌握和巩固知识的重要手段之一。近几年来,在中学物理教学中,特别是高中物理教学中,普遍地重视了这一工作。无疑地,这对于学生系统地巩固课内知识,养成学生正确的读书方法,提高学生阅读能力,起了一定的作用。但是,也有一些学校,一些教师对指导学生阅读教科书的工作作得不够,课堂讲授内容与教科书脱节,补充增加的内容过多,或讲授内容过深、追求严格,强调学生记笔记,甚至要求学生在复习时以笔记为主,而以教科书为辅。当然,也有一些学校,一些教师,在指导学生阅读教科书的方法上,要求过高过急。显然,这一切都不利于培养学生独立地阅读教科书的能力。我们初步了解到的一些不甚妥当的作法有下列几种:     

简析空间想象能力对高中物理学习的影响

通过大范围调查,研究了学生的空间想象能力差异的一些成因,并得到了一些启示.     

试谈指导学生阅读教科书的问题

一阅读教科书是学生掌握和巩固知识的重要手段之一,近几年来,在中学物理教学中,特别是高中物理教学中,普遍地重视了这一工作。无疑地,这对于学生系统地巩固课内知识,养成学生正确的读书方法,提高学生阅读能力,起了一定的作用。但是,也有一些学校,一些教师对指导学生     

提高学生实践应用能力的几例尝试

为了加强物理实验教学（包括演示实验和学生实验）,积极组织学生的第二课堂活动,启发和引导学生将所学物理知识用于生产、生活实践．几年来,在教学实践中,我们作了一些尝试．针对学校经费紧张,实验仪器不足这一困难,积极组织学生,自己动手,就地取材,制作了一些简...     

物理实验中有效数字的读取

有效数字的运用是中专物理实验技能培养的重要方面，但在实验过程中学生往往会在有效数字的读取上碰到一些问题．容易发生错误。就此作一些讨论，以引起重视，并在实验中加强对学生的指导。     

测定冰的熔解热实验探讨

对混合法测定冰的熔解热实验中的一些特殊情况进行了分析,通过对比发现几种情况最终可以归结为一个统一的结论,在对学生讲解该实验时可以引发学生思考,提高学生自我分析问题的能力.     

物理解题能力的培养

高考物理试题中,一些学生认为较难的题目,得分率很低．实际题目涉及的知识点并不难．究其原因,是学生解题能力有缺陷,所以,在教学中系统地、有针对性地对学生解题能力的培养是很有必要的．本文谈几点解“难”之法,帮助学生提高解题能力．     

“一个都不能少”——关于物理学科分层教学的探讨

分层教学模式是一种基于学生自身存在个体差异性而形成的一种新型的教育模式.在分层教学模式中,教师要针对不同学生的实际情况采取差别化教学,这样才能够最大限度地发掘学生的潜能.在本文中,笔者就如何在物理教学中实施分层教学提出了一些看法,希望能够为分层教学模式的有效实施提供一些参考.     

用一次性输液器制作的两个实验仪器

我们在教学过程中发现,课本中一些演示实验和一些学生实验采用的器材可操作性不强,往往会影响实验的结果.如果把一些实验的器材在原来的基础上加以合理改进,减小原来实验器材不足存在的影响,可以使得一些实验的对比性增强,还会大大地提高一些实验的成功率.     

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.