对实验课教学过程的思考

职业技术教育的特点是以培养学生动手能力为中心,以培养学生技能为目标,因此职业学校必须重视实验教学。通过实践,使学生认识、理解、验证基本概念和定律;训练学生基本操作技术;通过课程设计,生产经营实践,培养学生的职业能力。实验课的教学包括选题与准备、讲授与示范、操作与指导、评议与总结四个阶段。本文就这四个阶段的教学谈谈自己的一点思考心得。     

普通物理设计性实验的探讨

设计性实验可以是要求学生利用已掌握的知识和常用仪器所做的自命题的实验;也可以让学生进行开拓常用仪器的用法,对原有的实验仪器进行改良的实验;也可以由教师给出具体的实验目的,学生参考文献,分析最终选择最为优化的实验。     

实验教学中突出培养学生能力的探讨

十年来，我一直承担电磁学实验课的教学工作．对在实验教学中突出培养学生能力的问题，我深刻体会到：必须抓住实验课的几大环节，为学生创造一个培养和提高综合能力的实验课堂．一、激发学生对物理实验课的兴趣物理实验教学的重要目的是通过实验课，使学生能学到很多基本的实验方法，增强实验技能，培养学生自己索取知识的能力．所以，在实验的结论课上，我们把激发学生对实验课的兴趣放在首位．一方面要给学生讲述一些典型物理实验在科学发展史中所起的重要作用，另一方面还强调指出在科学技术高速发展的今天，实验仍然是开拓新领域的有力…     

对物理实验的深层思考

物理是一门以实验为基础的学科，对实验的多方位、多角度的思考能全面提高学生的思维水平，培养学生综合运用所学知识解决实际问题的能力，本文以“用单摆测量重力加速度”的学生实验为例，从数据处理、实验条件、实验目的、实验原理等几个方面，就如何进行对实验进行多层面的思考谈几点看法。     

论"边学边实验"型课堂教学的功能

物理是一门以观察和实验为基础的科学．根据这一自然科学的特点，应积极把实验活动引进课堂教学，在教师指导下，学生利用各种实验手段进行实验操作探索，并对所探索的问题进行交流和讨论，分析解决物理问题．加强实验教学，调动学习积极性，提高物理教学效果和开发学生创造能力，把传授知识和培养能力有机结合，这在加强素质教育的今天，尤其重要．做好课堂演示实验，重视学生的参与；在学生分组实验中，指导好学生自己动手操作实验，尽量采用探索式的实验方式；     

设计性物理实验教学探讨

结合我校开设的大学物理实验,在提高学生查阅资料并进行综合分析的能力、提高实验操作技能、培养学生科研能力方面,对设计性实验教学目的及方法进行了一定的探索。     

测量一般长度、微小长度、微小增量的设计性实验

本阐述了力学实验中的长度设计性实验。从实验题目、实验方案的拟订、仪器的配置、测量和操作，给学生提供了较大的空间，调动了学生的独立创造意识。     

发展实验思维能力 促进实验能力提升——2009年至2019年高考全国卷Ⅰ物理实验题分析及教学启示

物理实验思维能力是物理实验能力的核心,提升学生的物理实验能力首先要发展学生的物理实验思维能力.通过建构物理实验思维结构并分析近11年来高考物理实验题对学生实验思维结构中思维内容和过程两方面的考查情况,总结出解决高考重点实验问题所需的实验思维材料以及常用的思维方法,为实验教学中提升思维主体要素、全面促进学生实验思维能力的发展提出合理建议.     

充分发挥学生实验的作用

培养学生的实验能力是物理教学的重要任务之一 ,而培养实验能力最重要的手段是学生分组实验 .通过学生直接参与实验 ,理论联系实际 ,其实验能力才会得到培养和提高 .因此 ,学生实验在物理教学中具有十分重要的作用 .1　通过学生实验 ,提高实验技能和技巧学生实验是在学生动手操     

高二学生物理实验能力研究

对高二学生物理实验能力进行了调查研究,了解了学生实验能力的现状、特点、为培养学生的实验能力提供一定的依据。     

A study on the best irradiation dose of X-ray for Hep-2 cells by Fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy (FTIR) was employed to study the human epidermis larynx carcinoma cell lines (Hep-2) which were irradiated by different doses of X-ray.The results show that (1) the irradiation of X-ray damages the structure of the CH3 groups of the thymine in DNA,which restrains the reproduction of Hep-2 cells effectively,(2) the 8 Gy dose of X-ray irradiation changes the framework and the relative contents of some proteins,lipids and the nucleic acid molecules intercellular in the greatest degree,and (3) the 8 Gy dose of X-ray irradiation is the best irradiation dose for lowering the degree of the cancerization of Hep-2 cells according to the criteria for the degree of the cancerization reported recently.Meanwhile,the apoptosis of these cells were detected by using flow cytometry (FCM) primarily.It shows that the apoptotic ratio of the Hep-2 cells depends on the irradiation dose to some extent,but is not linearly.And the apoptotic ratio of the 12 Gy dose group is the maximum (20.36%),but the apoptotic ratios of the 2 to 8 Gy dose groups change little.     

Modification to first-order Born approximation for improved prediction of scattered sound from weakly scattering objects

When deriving the Fourier diffraction theorem based on the first-order Born approximation,the difference between wave number of the scattering object and that of the surrounding medium is ignored,causing substantial errors in sound scattering prediction.This paper modifies the Born approximation by taking into account the amplitude and phase changes between the scattering object and the water due to the wave number difference.By changing the radius and center position of the sampling circle in the Fourier domain,accuracy of the predicted sound scattering is improved.With the modified Born approximation,the computed far-field directional pattern of the scattered sound from a circular cylinder is in good agreement with the rigorous solution.Numerical calculations for several objects with different shapes are used to show applicability and effectiveness of the proposed method.     

Study on the radiation problem caused by electron beam loss in accelerator tubes

The beam dynamic code PARMELA was used to simulate the transportation process of accelerating electrons in S-band SW linacs with different energies of 2.5, 6 and 20 MeV. The results indicated that in the ideal condition, the percentage of electron beam loss was 50% in accelerator tubes. Also we calculated the spectrum, the location and angular distribution of the lost electrons. Calculation performed by Monte Carlo code MCNP demonstrated that the radiation distribution of lost electrons was nearly uniform along the tube axis, the angular distributions of the radiation dose rates of the three tubes were similar, and the highest leaking dose was at the angle of 160° with respect to the axis. The lower the energy of the accelerator, the higher the radiation relative leakage. For the 2.5 MeV accelerator, the maximum dose rate reached 5% of the main dose and the one on the head of the electron gun was 1%, both of which did not meet the eligible protection requirement for accelerators. We adopted different shielding designs for different accelerators. The simulated result showed that the shielded radiation leaking dose rates fulfilled the requirement.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Factors affecting the spectrum of an electromagnetic light wave on scattering from a semisoft boundary medium

The spectrum of an electromagnetic light wave on scattering from a semisoft boundary medium is discussed within the accuracy of the first-order Born approximation. It is shown that spectral shifts and spectral switches are affected both by the polarization of the incident light wave and by the characters of the scat-tering medium. Moreover, numerical results show that the direction at which the spectral switch occurs is governed by the characters of the scattering medium, whereas the magnitude of the spectral switch is affected by the polarization of the incident light wave.     

Temperature Sensitivity Control and Mechanical Stress Effect of Boron-Doped Long-Period Fiber Gratings

We will present in this work the quantitative analysis of the relationship between the doping concentrations of GeO 2 and B 2 O 3 in the core and cladding regions and the temperature sensitivity of the resonance wavelength shift in long-period fiber gratings (LPFGs). Based on this analysis, the temperature sensitivity was suppressed and enhanced to 0.002 nm/°C and 0.28 nm/°C, respectively. We will also discuss the effect of the residual mechanical stress on the optical and mechanical properties of LPFGs. In particular, we will present the measurement results of the dependence of the refractive index change and mechanical strength on the residual mechanical stress in the boron-doped fibers with depressed clad and matched clad.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

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.     

Exploitation of the Fiber Capacity in Optical Networks Using Time, Frequency, and Space Division Multiple Accesses

In this work we investigate how to obtain very high capacity transmissions in optical networks taking into account the limitations due to the physical channel. We consider both the case in which all the users are connected by a star coupler and the case in which the users are directly connected by the network topology. As a reference, we consider a ring network and a Shuffle Multihop Network (SMN). The use of optical systems to implement high-capacity networks is numerically investi gated by means of numerical simulations taking into consideration the channel limitations due to the chromatic dispersion, the Kerr effect, and the amplified spontaneous emission (ASE) noise of the optical amplifiers. In our model, we consider that the signal, during the routing process that is performed at the user position, undergoes only an attenuation. We suppose the use of intensity modulated signals and receivers with direct detection. Packet switching and digital transmission are assumed with soliton and conventional nonreturn to zero signals. Both wave length and time division multiple accesses are considered. The results show that, in the case of the Time Division Multiple Access (TDMA) technique, the use of a star coupler to connect the users reduces the capacity of a network with respect to the case in which a direct connection of the users is used. This is due to the strong power fluctuations that are present during the signal propagation and to the large quantity of accumulated ASE noise. On the other hand, the use of a star coupler shows the advantage to being easily reconfigurable. The Wavelength Divison Multiple Access (WDMA) technique permits us to achieve higher capacities with respect to the TDMA. This is due to the fact that in the propagation conditions, due to the presence of a star coupler, high bit rate signals are strongly degraded. On the other hand, several low bit rate signals operating at different wavelengths can propagate with a low power level, avoiding strong degradation due to the Four Wave Mixing (FWM) effect. Among the topologies considered in this work, the SMN is the one that generally permits us to reach the highest throughput because in the SMN the signal hops in a limited number of Network Interface Units (NIUs) before reaching the final destination.     

Time domain finite volume method for the transient response and natural characteristics of structural-acoustic coupling in an enclosed cavity

A time domain finite volume method（TDFVM）based on wave theory is developed to analyze the transient response and natural characteristics of structural-acoustic coupling problems in an enclosed cavity.In the present method,the elastic dynamic equations and acoustic equation in heterogeneous medium are solved in solid domains and fluid domains respectively.The structural-acoustic coupling is implemented according to the continuity condition of the particle velocity along the normal direction and the normal traction equilibrium condition on the interface.Several numerical examples are presented to validate the effectiveness and accuracy of the present TDFVM.Then the effects of water depth on the acoustic and vibration characteristics and the natural characteristics of a structural-acoustic coupling system are analyzed.The numerical results show that the increase of water depth leads to a stronger coupling between the water and structure and the decrease of natural frequencies of coupling system,The computational cost and memory of this method are small and it can be applicable to structural-acoustic coupling problems in the heterogeneous fluid.