与“探究型学习模式”结伴而行

新一轮的高中物理课程改革正在如火如荼地进行,围绕着创新意识与实践能力的培养,转变学习方式、注重探究型学习成了课程改革的重中之重."探究型学习"已经成为三维目标体系中"过程与方法"目标达成的核心载体.这种理念要求教学朝着自主学习、合作学习、探究型学习的方向发展;其中一个重要而具体的内容就是改变被动的接受式学习方式,倡导主动参与的探究型学习模式.     

浅析物理开放题的编制

《物理课程标准》明确提出物理课程的基本理念为“注重学生发展，改变学科本位；从生活走向物理，从物理走向社会；注重学科探究，提倡学习方式多样化；建构新的评价体系．”物理开放题由于自身的一些独有特点而能够在实际教学中充分体现物理课程的基本理念．近年来，物理开放题作为一种新的题型越来越受到人们的青睐．     

物理探究学习的课堂评价探析

把物理探究学习融入物理课程与教学实践之中已成为当今物理教育改革发展的一个重要特征．1996年美国《国家科学教育标准》把科学探究列入其“科学内容标准”之首；2000年英国颁布的国家课程把科学探究作为科学课程的四个目标的首要目标；2003年3月31日我国教育部颁布的《普通高中物理课程标准（实验）》所倡导的课程理念中明确指出“科学学习要以探究为核心．探究既是科学学习的目的，又是科学学习的方式”．“物理课程的核心理念是培养学生的科学素养”．“发展学生的科学素养又离不开科学的学习过程．科学的核心是探究，教育的重要目标是促进学生的发展，物理课程应当体现这两者的结合，突出物理探究学习方式”．而物理探究学习的课堂评价在学生物理探究学习过程中起着至关重要的作用．     

探究性学习在声速测量实验课中的运用

为了进一步提高大学物理实验课堂教学的质量,根据探究性学习的特点,构建声速测量实验课的实验教学过程,采用创建探究方向、拓展探究方向和加大探究自由度及激励机制,从而提高了大学物理实验课堂教学的自主性、实践性、开放性和激励性。     

物理教学实施探究式学习的三个原则

新课程标准明确指出：“高中物理课程应促进学生自主学习，让学生积极参与、乐于探究、勇于实验、勤于思考．通过多样化的教学方式，帮助学生学习物理知识与技能，培养其科学探究能力，使其逐步形成科学态度与科学精神．”因此，物理教学中探究式学习应着力于学生学习方式的改善，让学生体验科学探究过程，了解科学研究方法，增强创新意识和实践能力；激励学生在教学过程中主动学习和探究精神，调动学生学习的主动性、积极性，促进其个性全面健康地发展和情感、态度、价值观的自我体现．但目前的教学中，仍存在一定的认识误区和实践中的错误倾向．笔者根据对探究式学习的理解和实践认为物理教学的本质是科学的学习，而科学探究是科学学习的核心．可以说，中学物理教学的最终目标应是在学习物理知识的过程中，初步培养学生建立科学探究的意识和能力．为了达到这个目标，应在平时教学中引导学生进行探究式学习．在教学中实施探究式学习还应注意三个原则．     

WebQuest——网络探究学习

1 WebQuest简介 所谓WebQuest,就是利用互联网资源,引导学生对某个或某类问题(课题)进行学习、探究.这种学习方式是1995年美国圣地亚哥州立大学教育技术系的伯尼·道奇博士和汤姆·马奇创建的.     

以问题为载体,培养学生的科学探究能力——"伏安法测电阻"探究教学设计

1 设计思想 “探究学习方式特别强调问题在学习活动中的重要性．一方面强调通过问题来进行学习，把问题看作是学习的动力、起点和贯穿于学习过程的主线；另一方面通过学习来生成问题，把学习过程看成是发现问题、提出问题、分析问题和解决问题的过程．”物理教师应该是科学问题的开发者．有必要对一些探究的物理问题创设一些情境，让学生在观察和体验中有所发现，有所联想，萌发出科学问题；或者创设一些任务，让学生在完成任务中运用科学思维，自己提炼出应探究的科学问题．启发学生提出科学问题是非常重要的，这正如爱因斯坦所说的：“提出一个问题往往比解决一个问题更重要．因为解决问题也许是一个数学上或实验上的技能而已，而提出新问题，新的可能性，从新的角度去看待旧的问题，却需要有创造性的想象力，而且标志着科学的真正进步．”在“伏安法测电阻”的教学活动中，笔者以问题为载体，激活学生思维，培养学生的科学探究能力，取得了良好的教学效果．     

发展研究型基础物理实验教学的理念与实践

随着高校科研的快速发展,传统实验教学模式面临新的挑战.北京大学基础物理实验教学中心坚持科研引领实验教学的理念,立足于基础物理实验课教学,结合科学研究,探索研究型教学的实验课程模式,创建了基础与创新协同发展的基础物理实验课程教学新体系.在实验过程中,鼓励学生自主探究,通过查阅资料,设计方案,完成实验和交流成果,培养学生的科学精神,提高学生的科研能力.     

课外自主以趣导行

新课程强调要使学生适应终身学习的要求，具有终身学习的基础知识、基本技能和方法；倡导学生主动参与，乐于探究，勤于动手；培养学生搜集和处理问题的能力，获取新知识的能力，分析和解决问题的能力．要让学生具备这些能力，仅靠课堂45分钟是不够的，而需要教师指导学生在课外开展自主学习，使课堂教学目标的完成在课外得到有力补充．     

动量定理的探究式教学

高中物理新课标对物理教学改革的指导思想：一是教法要朝探究式教学方向变革；二是课教学要改变学生的学习方式，积极倡导探究性的学习方式．宗旨是培养学生的探究能力，提高学生的科学素养，我们应努力，     

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.