发光二极管在几个电磁学实验中的应用

采用发光二极管对电磁感应现象、自感现象、互感现象和电磁振荡等演示实验进行了改进,明显地提高了实验效果．     

光子人工微结构材料中的若干类量子现象

类量子现象又称为量子现象的经典对应(quantum-classical analogies),它是利用经典波动行为与量子波动行为的相似性来模拟和研究量子现象.近年来,光子人工微结构材料中类量子现象研究很活跃,文章对这方面的有关研究进展做了简要介绍.内容主要包括光子晶体和超构材料(metamaterials)中的类凝聚态系统量子现象和类原子系统量子现象,如类石墨烯量子现象、类拓扑绝缘体量子现象、类量子动力学现象、类Rabi振荡现象、类电磁感应透明现象、类Fano共振现象等.     

从负折射现象重新认识波

负折射现象是近年来被大量研究的一类有趣现象,它使人们对波动现象有了更深的理解,并推动了电磁新材料研究的发展.但是,负折射材料与通常正折射材料有很大不同,其中的物理原理不容易理解.文章用简单易懂的理论推演分析了负折射现象的物理起源,重新审视了波动方程的求解过程,并讨论了负折射现象给我们带来的启示.     

对自感现象中灯泡亮度的研究

本文通过对演示自感现象实验中灯泡亮度的问题讨论 ,对自感现象进行电路分析 ,加深了对自感现象的认识     

用弹性双轨演示曲线运动中的超重与失重——第五届全国自制教具评选获奖作品之三

1 实验目的 超重、失重现象较为常见,也很重要.虽然学生对超重、失重现象有所了解,但仍缺乏感性认识.为了让学生从电梯、过山车现象中的感觉上升到直接"看到"超重、失重现象,抓住这个稍纵即逝的现象,我们设计了弹性双轨,以此更加直观地观察超重、失重现象.     

两端固定张紧弦"异常"共振现象

用弦音计做两端固定弦振动实验中出现了和音叉计不同的共振现象,如长春五光的仪器出现了 f0 ∶fk=1n∶1的共振现象,PASCO公司的产品出现了f0∶fk=12n∶1的共振现象,本文分析和解释了这些现象产生的原因,并提出了实验改进方案.     

低温液体输送系统间歇泉现象机理分析与消除措施

在低温液体输送系统的垂直管路中有可能发生间歇泉现象 ,对管路系统和液体储存都会产生不利影响。文中从气泡动力学、间歇泉循环过程、管路结构等方面对低温液体输送系统中出现的间歇泉现象进行了机理分析 ,介绍了几种消除间歇泉现象的措施 ,为进一步研究间歇泉现象提供了理论基础     

光学三稳态系统中的慢化现象

研究了光学三稳态系统的现两种慢性现象。一种是发生在两类临界点附近的慢化现象,计算出了它们的临界慢化指数,另一种远离临界点的慢怀现象,这是一种与稳工作点有关的慢化现象。本文的讨论具有一定的普适性。     

超声复合振动系统中的“局部共振”现象──20年来的应用和机理分析情况

本文作者及当时合作者在《应用声学》的创刊号中报道了超声振动系统中“局部共振”现象的发现及其一项应用。20年来,国内一些作者或者分别介绍了本现象在不同场合的应用,或者分别分析了这个现象的机理。值此《应用声学》庆祝创刊20周年之际,西文回顾了这些前期工作,提出了自己的一种关于机理的观点,并对“局部共振”现象的实用意义作了新的评价,希望能进一步促进这个现象的应用和对它的讨论。     

永磁体同性磁极相吸现象的研究

永磁体的磁极同性相斥异性相吸现象是人所共知的常识,但在一定条件下却能表现出同性磁极相吸现象．本文对这一现象进行了讨论．     

Vapour and plasma ignition thresholds for visible pulsed-laser ablation of metallic targets

The coupling of visible nanosecond laser pulses to metallic targets irradiated in vacuum is studied. The expressions of the vapour and plasma ignition times are obtained. Two cases for vapour breakdown in the plasma ignition process are considered. The first case is that 40 generations of new electrons are born in vapour generation time before plasma formation as assumed in the literature. The second case is that 10 generations of new electrons are born in vapour generation time. Molybdenum (Mo), niobium (Nb) and aluminium (Al) targets are considered for illustrations of our results. The expression of the plasma ignition time for the Al target is substantially different from that reported in the literature. The vapour and plasma ignition threshold laser intensities are calculated and compared with those reported in the literature. Reasons for disagreement are discussed. The plasma ignition threshold estimated in the second case is noted to be in good agreement with the reported experimental result.     

Electronic structure of hydrogen and muonium in Al,Mg and Cu

The electronic structure of hydrogen and muonium in simple metals is investigated. The spherical solid model potential is used for the discrete lattice and the Blatt correction for lattice dilation. The proton and muon are kept at the octahedral sites in the fcc and hcp lattices and self-consistent non-linear screening calculations are carried out. The scattering phase shifts, electronic charge density, effective impurity potential, self-energy, charge transfer, residual resistivity and Knight shift are calculated. The spherical solid potential changes the scattering character of impurity. The phase shifts are found slowly converging. The scattering is more prominent in Al than in Mg and Cu. The virtual bound states of proton and muon are favoured in all the three metals. The calculated value of residual resistivity for CuH is in good agreement with the experimental value. The results for Knight shift forμ ⁺ in Cu and Mg are in reasonable agreement with the experimental values while those forμ ⁺ in Al are lower than the experimental value. The analytical expressions for effective impurity potential and electronic charge density are suggested.     

生物芯片扫描仪研究进展

介绍了生物芯片及其检测、扫描的基本原理。详细讨论了在生物芯片扫描仪中的关键技术及国内外的研究现状和目前存在的技术难点以及最新发展趋势和研究热点。着重分析了共聚焦光路与非共聚焦光路在生物芯片扫描仪中的应用特点,以及CVR技术指标。最后提出了生物芯片扫描仪的未来研究重点以及发展方向。     

Investigation on the electronic transport properties of MgS nanotube based molecular devices – a first-principles study

The electronic transport properties of pure MgS nanotube based molecular devices, Mn-substituted nanotubes and Se-substituted nanotubes are investigated using density functional theory. The state of the art of this work is to study the transport properties of MgS nanotubes with substitution impurities across electrodes. The electronic transport properties are discussed in terms of device density of states and transmission spectrum of MgS nanotubes. The effects of Mn substitution and Se substitution in nanotubes are studied. The major contribution to density of states arises only from p orbitals in MgS nanotubes. The substitution effect and bias voltages also have influence in the density of states. The transmission spectrum provides information about the transmission of electrons along the nanotube. The information provided in this work gives a clear vision to fine-tune MgS nanostructures with improved transport property in nanoelectronic device fabrication.     

Retinex彩色图像增强理论的物理思考及其截断区间对图像质量的影响

指出了Retinex彩色图像增强理论的物理意义,在对数空间中,将原图像减去高斯函数与原图像的卷积,其物理本质是除去了原图像中的平滑的部分,突出了原图像中的快速变化的部分,而且高斯函数越尖锐,越是突出图像中的细节,高斯函数越平坦,图像色调保持得越好,多尺度Retinex综合了不同高斯函数与原图像进行卷积的优点。研究了多尺度Retinex标准差截断法,结果是,以多尺度Retinex处理后的图像强度在其平均值附近1倍标准差截断后再拉伸得到的图像,普遍好于以2倍、3倍标准差截断后再拉伸得到的图像。     

Modeling and Analysis of Anomalies in the Network Infrastructure Based on the Potts Model

The paper discusses issues concerning the occurrence of anomalies affecting the process of phase transitions. The considered issue was examined from the perspective of phase transitions in network structures, particularly in IT networks, Internet of Things and Internet of Everything. The basis for the research was the Potts model in the context of IT networks. The author proposed the classification of anomalies in relation to the states of particular nodes in the network structure. Considered anomalies included homogeneous, heterogeneous, individual and cyclic disorders. The results of tests and simulations clearly showed the impact of anomalies on the phase transitions in the network structures. The obtained results can be applied in modelling the processes occurring in network structures, particularly in IT networks.     

Analysis of dusty plasma in the positive column of glow discharges

The radial distributions of ions,electrons and dust particles in the positive colum of glow discharges are investigated in a tripled-pole diffusion model.The dust particles are mainly trapped in the region around the column axis where the electrostatic potential is the highest.The presence of the dust particles results in the ion density increasing and the electron density decreasiung in the dust-trapped region.The dust-trapped region is wider for a higher dust temperature or a smaller particulate redius.The ions and electrons in the dust-free region away from the column axis are in ambipolar diffusion.     

Isospin-dependent relativistic microscopic optical potential in the Dirac Brueckner-Hartree-Fock method

There is growing evidence to suggest that the binding energy of nucleon in nuclear matter comes from a cancellation between large Lorentz scalar and vector potentials[1,2]. The relativistic approach has been of a great success in describing not only the ground state properties of stable nuclei, but also those of exotic nuclei. In the relativistic frame, the spin-orbit coupling can be deduced automatically, which is usually given by hand in the non-relativistic approach. The relativistic method…     

Wavespeed analysis: Approximating Arrhenius kinetics with step-function kinetics

The accuracy of using step-function approximations to the Arrhenius exponential in computing the wavespeed in combustion wave propagation is investigated. Gaseous and gasless combustion, and first- and second-order reactions are included in the study. The theoretical analysis is based on Melnikov theory from dynamical systems. The error is shown to be small in most instances. The analytical results are supported with numerical simulations.     

Changes in ADC caused by tensile loading of rabbit achilles tendon: evidence for water transport

Water diffusion measurements were performed on rabbit Achilles tendons during static tensile loading and tendons in an unloaded state. The apparent diffusion coefficient (ADC) was measured along two directions: parallel and perpendicular to the long axis of the tendon. Tendons were studied after being prepared in two ways: (a) after being stored frozen in phosphate-buffered saline (PBS) and (b) freshly isolated. Statistically significant directional anisotropy was observed in the ADC in all tendons. The ADC was significantly greater in the direction parallel to the long axis of the tendon than in the perpendicular direction. The anisotropy is attributed to the greater restrictions seen by the water molecules in the perpendicular direction and is consistent with the known geometry of the tendon. Storage in PBS caused tendons to swell. This increased the ADC measured along both directions and reduced the anisotropy. The existence of anisotropy in the ADC was not related to the orientation of the specimen in the magnet. The ADC increased along both directions following the application of a 5-N tensile load; the increase was greatest along the perpendicular axis of the tendon. In order to determine whether load-related changes in the ADC reflected changes in interfibrilar spacing, we used electron microscopy to measure load-related changes in fibril spacing. Load-related changes in fiber spacing could not account for the observed changes in the ADC. The increase in ADC caused by loading was attributed to the extrusion of tendon water into a bulk phase along the outside surface of the tendon. In PBS-stored samples, enough fluid was extruded that it could be visualized. The transient response of the ADC to a 5-N tensile load was also studied. The absolute ADC in both directions increased with loading and recovered to baseline upon unloading. The transient changes in ADC, for both loading and unloading, had a mean time constant of approximately 15 min. The magnitude of the load-induced transient ADC changes was comparable to that seen in the static-loading experiments.