声音传播实验的改进

现行课本上介绍的声音传播实验，要么使用抽气机，使瓶内气体变稀薄；要么使用烧瓶将水烧至沸腾，加盖冷却后使瓶内气体变稀薄．然后，由气体逐渐变稀，传出的声音逐渐减小进行推理，从而得出“声音在真空中不能传播”的结论．此类实验的不足之处是器材较多，实验的时     

光通信实验设计

提出了一个适合理工科大学物理实验教学的光通信实验系统，介绍了该实验的工作原理，实验装置和调整步骤；该实验以简单的光学元器件组合，演示了现代光通信的基本工作过程。     

动量定理定量探究实验的设计

采用美国PASCO公司生产的“科学工作室”物理实验系统重新设计动量定理实验，以定量分析的实验形式，弥补了传统“动量定理”实验的不足。     

重视物理实验中的演示实验

本文根据物理实验教学的特点，对在普通物理实验中重视开设演示实验进行了讨论，并做了几点尝试。     

浅谈物理原理对物理实验的指导作用

实验原理是物理实验的核心，本文通过对具体案例的分析指出：正确理解实验原理是实验科学性的基本保证，深刻理解实验原理是突破实验难点的关键，掌握实验原理是领会实验设计思想的前提，挖掘实验原理的内涵则是教学创新设计的出发点．     

中学物理实验归类与设计

物理实验既是教学的重要基础又是教学的重要内容、方法和手段，在物理教学中学会设计实验是物理教师应该具有的重要素质．通过对课本实验分析归类，提出实验设计的几种思路，旨在以实验为契机，优化物理教学．     

值得重视的定性,半定量物理实验

本文明确提出了一类新的实验一定性、半定量的物理实验，论述了这类实验在培养学生创新能力方面的作用和意义，最后介绍了国外及作者在这方面的实践情况。     

考核物理实验能力的笔试与操作考试的比较

一、高考中物理实验考核的现状与问题众所周知，在大规模考试中组织实验操作考试困难很大，在现有的条件下困难就更大．作为权宜之计，以实验笔试代替操作考试也不失为一种办法．从历年高考物理试题看来，高考中物理实验笔试题有如下主要特占[1,2]:1．有逐年加大实验笔试题比例的趋势，反映出对考查实验能力的重视，但另一方面，绝对分数的增加并不大；2，题型趋于稳定；3．考查日趋全面，涉及实验原理、步骤、仪器使用、器材选择、读数记录、实物图连接、看图改错、数据处理等．由此可见，高考中对实验笔试的考核办法已经成熟和定型，对促…     

实验教学中提高学生能力的尝试

师范专科学校的教育是为了培养合格的初中教师，随着社会的进步对人才的要求越来越高，就初中物理教师而言，不但要有扎实的理论知识，还应有一定的实验技能和实验室管理能力，所以如何提高培养学生的实验技能和实验室管理能力在实验教学中显得十分重要和必要．针对这两个问题我们在实验教学中做了一些改革的尝试，收到了一定效果，现概括如下．一、开放实验室，提高学生的实验技能提高学生实验技能关键问题是要给学生提供一个较好的实验环境，这包括足够的实验装置和更多的动手机会．但由于许多学校实验经费有限，很多实验装置在数量上不能…     

值得重视的定性、半定量物理实验

本文明确提出了一类新的实验—定性、半定量物理实验，论述了这类实验在培养学生创新能力方面的作用和意义，最后介绍了国外及作者在这方面的实践情况     

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.     

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.     

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.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

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.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.