用双车实验探究加速度与质量和力之间的关系

物理学是一门以实验为基础的科学,实验能力是高考要求考查的五种能力之一．高中物理实验包括学生分组实验和教师演示实验．高考实验考查内容要求是来源于学生实验而又高于学生实验,要能充分体现平时认真做过实验与没做过实验的学生答题时有很大区别．因此就要求教师在平时的实验课堂教学中注意培养实验动手能力及实验探究、创新和迁移能力．熟悉平时所做过的每一个实验,特别是实验原理及实验数据的处理方法,从而触类旁通,利用所给的实验要求进行实验设计及探究．下面以实验探究加速度与质量、力之间的关系为例来谈谈做这一实验时的教学创新．     

大学物理实验的简化与深化

以复摆实验、地磁实验和衍射光栅实验为例,说明在大学物理实验中,通过提供简单的实验器材,就可以将实验内容延伸扩展,将原来内容单一的实验扩展为多层次、多目的的实验项目,实现大学物理实验的简化与深化.     

“光的折射”实验改进技巧

中学物理实验,有的实验好说难做,有的实验由于学校实验器材的限制无法改为学生实验,有的实验演示效果不好,没有足够的可观度,有的实验复杂不易成功.所以,在进行教学时,就变学生探究实验为教师演示实验,或者直接借助多媒体进行模拟实验.使物理实验失去了真实感,学生对实验的理解缺少一定的感性认识,学生不能亲自参与实验,而用课件模拟实验又没有真实感,大大地影响了学生学习物理的积极性,为此笔者在"光的折射"教学设计中尝试改进了一些教具和实验方法,解决了实验教     

探索性实验

我校编写的《物理实验教程》中,把物理实验分为三大类,即探索性实验、验证性实验及应用性实验。后两类实验(尤其是应用性实验)在传统的物理实验课程中已有大量的现成课题,且对每个具体的实验常有多方面深入研究的报道。但极少见到有关探索性实验的介绍(《物理实验》1982年第4期载有《逆行式实验》一文),而探索性实验是一类很有科学意义的实验类型,它有助于学生科学实验能力的培养,因此它应在物理实验课程中占有一席之地。通过实验去寻找有关物理量之间的函数关系式(或称经验公式),从而揭示其内在的物理规律。以此作为目的的一类实验称之谓探索性实验。它是物理规律研究的起始,科学实验的原貌。由于教学时数及实验室各种     

从磁悬浮导轨动力学实验简析大学生实验技能的培养

磁悬浮导轨动力学实验因涉及到先进的磁悬浮技术而受到大学生的青睐。文中以该实验为例,探讨大学生实验技能的培养。磁悬浮导轨动力学实验虽然原理简单,但实验内容丰富,有助于学生实验技能的训练。分析认为,可以从实验数据点的采集、实验思想的培养、实验结果的正误判断、错误实验结果的原因排查、误差的减小和数据的处理等方面来培养学生的实验技能。     

受激布里渊散射(“SBS”)实验

本文简述了受激布里渊散射实验原理,实验装置及主要实验方法,分析了典型实验范例。讨论了在近代物理实验中开设受激布里渊散射实验的目的和意义。     

物理实验教学改革探讨点滴

传统的物理实验教学方法,基本上遵循着下列楷模,即在实验指导书中,先列出实验目的、实验设备、实验原理,而实验步骤及实验数据处理,则完全统一规程、统一格式。刻板枯燥,很难提起学生对物理实验的兴趣,使学生呆板、机械、被动应付。实验时,学生往往尚未对整个实验机理全面理解,     

初中生物理实验能力的发展特点及其培养

物理实验能力是指运用实验理解、验证物理理论观点以及借助物理实验获得新认识的能力,它由实验基本能力、实验迁移能力和实验科研能力构成.本文分析了初中生物理实验能力发展的特点,指出了在初中实验教学中应重点培养第一级和第二级实验能力.     

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     

对焦耳定律实验装置的一种改进

在初中物理的电学演示实验中，研究焦耳定律的实验是很重要的一个．教材中该实验有一缺点，实验过程时间太长——整个实验需30分钟左右；实验现象也不很明显，实验过程中煤油柱的上升非常缓慢，学生觉得索然无味，不能感受到实验带来的乐趣；实验也很难得出电流流过导体产生的热量跟电流、电阻、时间的关系．     

A subspace fitting algorithm of acoustic vector sensor array and corresponding matrix pre-filter design

In order to ease the pass-band response distortion of the matrix pre-filter,a simple approach for designing matrix spatial filter is proposed,which minimizes the sum of the k maximal distortion norm（k is the number of the constraint points）within the pass-band,while constraining the filter response within the stop-band.Considering the costly amount of calculation of the high-resolution methods,an algorithm with small amount of calculation based on matrix pre-filtering and subspace fitting using acoustic vector array（MF-VSSF）is proposed.Through joint processing of signal subspace of both pressure and particle velocity,the pre-filtering matrix and the signal subspace is decreased to M-dimensional（M is the number of array-element）,hence reduces the time-consumption of the matrix pre-filter design and DOA searching.Simulation results show that,the method offers the same performance as MUSIC with pre-filtering,but has much lesser amount of calculation.Moreover,the designed prefilter can efficiently suppress the interference in the stop-band and improve the estimation and resolution performance of successive DOA estimators.     

Influence of dielectric microcavity on the spontaneous emission rate of atom: a perspective on the closed-orbit theory of photons

The formulas of the quantum electrodynamics have been applied to calculate the spontaneous emission rate of excited atom in dielectric microcavity.The results exhibit damping oscillating Patterns which depend sensitively on the scaling parameter and geometrical structure.Compared with the case that the emitting atom is immersed in dielectric,the spontaneous emission rate is depressed obviously and the center or the mean value of the oscillations is intimately related to the real refractive index of the local position where the atom is.In order to explain this phenomenon,we utilize the closed-orbit theory to deal with the classical trajectories of the emitted photon.and extract the corresponding frequencies of the oscillations by Fourier transform.It is found that the oscillations can be represented in terms of the closed-orbits of the photon motion constrained in dielectric microcavity,thus providing another perspective on the spontaneous emission of atom sandwiched by dielectric slabs.     

Cooling induced by parametric resonance in a magnetic quadrupole trap

It is demonstrated experimentally that the anharmonic property of the quadrupole trap can be exploited to cool trapped atoms by modulating the trap potential anisotropically.This cooling effect arises from the energy-selective removal of the most energetic trapped atoms and the thermal equilibrium of the remaining atoms.The frequency dependences of the temperature and the fraction of the atoms left in the trap after the modulation are explored.It is also demonstrated that the cooling induced by parametric resonance can also increase the phase space density of the trapped atoms.     

含油纳米制冷剂沸腾中纳米颗粒相间迁移特性预测模型

为了评估纳米颗粒对沸腾传热的影响效果和采用纳米制冷剂的制冷系统长期运行稳定性,提出了含油纳米制冷剂沸腾中纳米颗粒相间迁移特性预测模型,通过模拟气泡的脱离和上升过程、纳米颗粒的运动、纳米颗粒与气泡的黏附、气液交界面上纳米颗粒的脱离,最终得到纳米颗粒的迁移量.该模型能够反映热流密度和加热容器几何结构等因素对纳米颗粒迁移特性...     

Sound scattering from partially water-filled elastic spherical shell with an internal elastic plate

According to the equation of motion in the elastic medium and integral equation of target scattering, the sound scattering from the partially water-filled elastic spherical shells with and without an inner plate is studied using the finite element and boundary element method, and the scattering normalized form functions of the shell filled with different volume of water are computed and the mechanism of resonance scattering is analyzed. The results show that the resonance of the shell with partially water-filled and without the plate is mainly related to the volume of water, and the resonance is produced by inner water and the spherical shell. The resonance characteristics of partially water-filled elastic shell with the plate are similar to that of empty structured elastic spherical shell, and the sound field in inner water is weaker which indicates the main resonance characteristics are decided by spherical shell and the plate. In addition, the scattering characteristics of spherical shell with plate and one side full water-filled are greatly different from the partially water-filled ones.     

On the non-synchronous rotation of binary systems

During the evolution of the binary system,many physical processes occur,which can influence the orbital angular velocity and the spin angular velocities of the two components,and influence the non-synchronous or synchronous rotation of the system.These processes include the transfer of masses and angular momentums between the component stars,the loss of mass and angular momentum via stellar winds,and the deformation of the structure of component stars.A study of these processes indicates that they are closely related to the combined effects of tide and rotation.This means,to study the synchronous or non-synchronous rotation of binary systems,one has to consider the contributions of different physical processes simultaneously,instead of the tidal effect alone.A way to know whether the rotation of a binary system is synchronous or non-synchronous is to calculate the orbital angular velocity and the spin angular velocities of the component stars.If all of these angular velocities are equal,the rotation of the system is synchronous.If not,the rotation of the system is non-synchronous.For this aim,a series of equations are developed to calculate the orbital and spin angular velocities.The evolutionary calculation of a binary system with masses of 10M⊙+6M⊙shows that the transfer of masses and angular momentums between the two components,and the deformation of the components structure in the semidetached or in the contact phase can change the rotation of the system from synchronous into non-synchronous rotation.     

Standard Model theory calculations and experimental tests

To present knowledge, all the physics at the Large Hadron Collider (LHC) can be described in the framework of the Standard Model (SM) of particle physics. Indeed the newly discovered Higgs boson with a mass close to 125 GeV seems to confirm the predictions of the SM. Thus, besides looking for direct manifestations of the physics beyond the SM, one of the primary missions of the LHC is to perform ever more stringent tests of the SM. This requires not only improved theoretical developments to produce testable predictions and provide experiments with reliable event generators, but also sophisticated analyses techniques to overcome the formidable experimental environment of the LHC and perform precision measurements. The present article proposes an overview of the present theoretical tools and of the experimental results in the field of strong and electroweak interactions.     

Synergistic effects on iodine release in potassium iodide solution by combination of ultrasound and visible light irradiations

Iodine release in potassium iodide solution has been investigated under the irradiations of ultrasound and visible light respectively and simultaneously. We have observed that the amount of iodine liberated under the combined irradiation of ultrasound and visible light is larger than the sum of that under the respective irradiations of ultrasound and visible light, indicating a synergistic effect of ultrasound and visible light irradiations. Based on the investigation of the reaction kinetics of iodine liberated, we have ascribed the synergistic effect to the perfect stirring of the photochemical reactor induced by the applying simultaneous ultrasound. The ideal stirring can result in the homogenization of the primary light effect in the whole reaction medium, which induces the acceleration of the photochemical reaction. On behavior of our knowledge, there are few reports on the investigations of utilizing the combination of ultrasonic energy and light energy to accelerate the reaction yield and rate as well as the kinetics of the reaction.     

Influence of substrate process tolerances on transmission characteristics of frequency-selective surface

Frequency-selective surface （FSS） is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units （or apertures） arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate＇s thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.     

Theoretical investigation of the electronic structure of a ferroelectric SbSI cluster at a phase transition

This paper presents the theoretical investigation of energy levels of valence bands (VB) and core levels (CL) of the ferroelectric SbSl single crystals in antiferroelectric and ferroelectric phases. Since the best approximation for the deep VB levels is a calculation by the Hartree-Fock method, the molecular model of a SbSI crystal was used for calculations. This model of the crystal was also used for calculations of the total density of states. It was found that the VB and CL of this ferroelectric semiconductor are sensitive to the small lattice distortion at the phase transition, and that an average of the total density of states, when all atoms participate in oscillations of all normal modes, are more similar to the experimental X-ray photoelectron spectra (XPS). The experimental splitting of CL obtained by XPS was compared with the theoretically calculated one by two different methods. The cluster model calculations showed that the splitting of the CL in SbSI might be caused by photoelectron emission from the atoms, which have different valence state, at the surface.