波尔共振仪实验的不确定度分析

共振现象普遍存在于物理学领域,高校开设波尔共振仪实验以加深学生对共振概念的认识,文中讨论了摆轮作自由振荡、阻尼振荡和受迫振动的测量结果的不确定度,并分析了可能影响测量结果的因素,该结果对理解共振现象和分析测量不确度具有一定的指导和借鉴意义。     

光伏型碲镉汞探测器在波段内连续激光辐照下的两种不同过饱和现象的产生机理

利用连续波段内激光对两批光伏型碲镉汞探测器进行了激光辐照实验, 发现了两种不同的过饱和现象. 实验表明, 光伏型碲镉汞探测器在强光辐照下都会出现开路电压随光强增强而减小的过饱和现象, 明晰了PV型探测器在强光辐照下的一般规律性现象和由探测器个体差异导致的特殊现象. 从等效电路模型出发, 剖析了两种过饱和现象的发生条件, 建立了数值计算的理论模型, 对两种过饱和现象进行了数值模拟, 计算结果与实验结果符合得较好. 研究表明, 光伏型碲镉汞探测器在波段内强光辐照下引起的过饱和现象有两种产生机理, 一种是热效应引起的暗电流增大机理; 另一种是探测器材料中缺陷引起的漏电流增大机理. 关键词： 波段内连续激光 光伏型碲镉汞探测器 过饱和现象     

峰值/谷值电流型控制开关DC-DC变换器的对称动力学现象分析

峰值电流和谷值电流控制开关DC-DC变换器在较宽的电路参数范围内具有对称动力学现象.文中建立了峰值电流和谷值电流控制buck,boost,及buck-boost变换器的统一离散迭代映射模型,并导出了统一的分段光滑迭代映射方程及特征值方程,通过数值仿真得到了占空比变化时的正、逆分岔图和Lyapunov指数谱.研究结果表明,峰值/谷值电流型控制开关变换器的分岔图和Lyapunov指数具有关于点或轴对称的现象.时域仿真结果验证了数值仿真结果,并进一步表明,随着占空比的变化,峰值/谷值电流型控制开关变换器具有对称动力学现象、对称动力学现象和非对称动力学现象共存、非对称动力学现象.     

峰值/谷值电流型控制开关DC-DC变换器的对称动力学现象分析

峰值电流和谷值电流控制开关DC-DC变换器在较宽的电路参数范围内具有对称动力学现象.文中建立了峰值电流和谷值电流控制buck,boost,及buck-boost变换器的统一离散迭代映射模型,并导出了统一的分段光滑迭代映射方程及特征值方程,通过数值仿真得到了占空比变化时的正、逆分岔图和Lyapunov指数谱.研究结果表明,峰值/谷值电流型控制开关变换器的分岔图和Lyapunov指数具有关于点或轴对称的现象.时域仿真结果验证了数值仿真结果,并进一步表明,随着占空比的变化,峰值/谷值电流型控制开关变换器具有对称动力学现象、对称动力学现象和非对称动力学现象共存、非对称动力学现象.     

超流研究的历史回顾

回顾了超流发现的历史，介绍了超流的一些现象、理论以及新近的研究结果。强调指出超流与超导一样是一种宏观量子现象。     

钽、铁、钨三种体心立方金属裂纹的多尺度模拟及韧脆性分析

采用多尺度准连续介质法计算模拟了钽、铁、钨三种体心立方(body-centered-cubic,BCC)金属的I型裂纹断裂过程.观察了加载过程中裂纹尖端区域原子的位错、孪晶等塑性变形现象,以及裂纹的脆性开裂和扩展现象.模拟结果表明,不同BCC金属材料的裂纹在相同的加载下有不同韧脆性表现.在一定变形范围内,钽裂纹主要表现出的是裂纹尖端附近区域原子的位错和形变孪晶等塑性变形现象;铁裂纹在变形过程中先后表现出了塑性变形和脆性扩展现象,与实验结果吻合;钨裂纹在变形过程中则主要变现出脆性扩展现象.计算了三种金属材料的广义层错能曲线,得到其不稳定层错能;并分别用两种不同的韧脆性准则,对三种材料断裂模型的韧脆性行为进行分析,计算分析结果与模拟结果一致,从而验证了模拟结果的正确性.     

核–核碰撞间歇现象的混合效应

通过对核-核碰撞中归一化阶乘矩反常标度性的一些实验结果的观察,发现在末态高维相空间中,阶乘矩和空间分割数的双对数图呈急剧上翘的现象. 经过仔细分析,用核-核碰撞是许多基元碰撞混合叠加的观点,对上述现象进行了定性的解释. 基于这一观点,建立了一个随机级联模型,用Monte Carlo方法给出了与实验现象的定性符合,讨论了这一结果的可能的应用.     

利用GeoGebra和Phyphox软件进行高效物理远程教育的探索--以拍现象的物理教学为例

以拍现象的物理教学为例,利用GeoGebra软件不仅演示了拍现象,而且能让学生通过网址链接进行方便的自我探索,接着又给出了手机软件Phyphox在家做实验探究拍现象的方法,并通过分析实验结果进行计算,得到的待测波频率的精确度可达到整数位.     

激光散斑漂移现象的理论模型与成像实验

基于傅里叶光学原理,建立了数值计算客观及主观激光散斑图样的方法.利用几何光学成像原理,推导了主观散斑现象中散斑及光斑漂移速率的表达式.搭建了成像实验装置,观察主客观散斑及其漂移现象.结合相关函数、快速傅里叶变换算法以及卷积定理,建立了基于图像处理定量计算散斑及光斑漂移量的方法.实验结果、数值计算结果、几何光学理论均互相符合,表明了数值方法与几何光学理论的正确性,为激光散斑漂移现象提供了系统性的研究方法和直观的理解.     

空间周期相干光照明下的自成像现象及Lau效应

借助模糊函数理论分析了空间周期相干光照明产生的自成像现象及Ｌａｕ效应。理论分析结果表明：当照明光源满足一定条件时，会出现自成像现象及Ｌａｕ效应。根据分析结果讨论了这些现象的可能应用。     

Meson-Meson Scattering on Anisotropic Lattices

Using the tadpole improved Wilson quark action on small, coarse, and anisotropic lattices, meson-meson scattering lengths are calculated within quenched approximation. The study covers pion-pion scattering in the I=2 channel and kaon-pion scattering in the I=3/2 channel. The results are extrapolated towards the chiral limit. Finite volume and finite lattice spacing errors are also analyzed and results in the infinite volume and continuum limit are obtained. Our results are compared with the results obtained using Roy equations, chiral perturbation theory, dispersion relations, and the experimental data. We also compare our results with other lattice results on the scattering lengths.     

用质点源方法计算三维内电磁脉冲

本文给出用质点法求解三维长方腔体中的初级电流及其相应的内电磁脉冲的数值结果。井把这种方法得到的结果与三维欧拉方法的计算结果作了比较。在相同的计算条件下,两种方法得到的结果符合较好。     

水位骤变时的饱和-不饱和渗流数值计算

本文应用全隐式交替方向迭代法对水位骤变时的饱和-不饱和渗流问题求出了数值解。对于赤井模型,计算结果与实验结果十分接近,比有限元法的计算结果好。对于大尺度的驹田蓄水池模型,计算结果与有限元法的结果基本一致。     

Elastic scattering of electrons by hydrogen atoms in the (2p) state

Conclusion Since our results are the first set of results in this field, their accuracy can be judged when further results through other methods and through experiment are available.The author is grateful to Dr. J. N. Das for his constant help and encouragement in the preparation of this paper. The numerical results reported in this paper have been calculated on the IBM 1130 at Calcutta University.     

Hydrogen Balmer-alpha broadening in dense plasmas

This work presents a theoretical analysis of experimental results for the hydrogen Balmer-alpha line in dense plasmas, with electron densities between 2x10(18) and 9x10(18) e/cm(3) A simulation of both electrons and ions is employed to produce reliable theoretical widths. These results are essentially in agreement with standard theory results and, for the most part, disagree with the experimental results. Consequently, either mechanisms not accounted for in the theoretical results (such as quadrupoles) are more important than previously thought at these densities, or else there is a problem in the experimental data (such as a possible reabsorption, which is not ruled out by the experimental data).     

PIV measurement of toner particle motion in a micro-gap in the development process of electrophotography

In the development process of electrophotography, charged dielectric toner particles move in a micro-gap between the photoreceptor and the development roller to form images by the action of electrostatic force. To improve image quality, it is important to clarify the toner particle motion and the effects of the electric field on this motion. In the present study, Particle Image Velocimetry (PIV) was applied to measure the toner particle motion and the results were compared to calculated results. It was confirmed that the toner velocity increased with increasing electric field intensity, and that the measurement results agreed with the calculated results. These results indicated the usefulness of PIV in analyzing toner particle motion in the development process.     

Next-to-leading-order results for five, six, and seven jets in electron-positron annihilation

We present next-to-leading order corrections in the leading color approximation for jet rates in electron-positron annihilation up to seven jets. The results for the two-, three-, and four-jet rates agree with known results. The NLO jet rates have been known previously only up to five jets. The results for the six- and seven-jet rate are new. The results are obtained by a new and efficient method based on subtraction and numerical integration.     

耦合带状线定向耦合器大功率合成器的设计

介绍了直线加速器高频全固态功率源中大功率合成器件-3 dB定向耦合器的理论计算和工程设计过程, 该合成器工作频率80.5 MHz, 输出连续波功率大于20 kW。 分析了合成器的功率容量, 并对相应的理论计算结果、 CST (Computer Simulation Technology)软件模拟计算结果和实际功率合成器件测量结果进行了比较。 通过比较得出, CST仿真结果与测试结果基本一致, 隔离度和电压驻波比等实测指标优于设计指标, 只有耦合度与设计指标有些偏差, 总体上达到了预期的设计要求。 在输出功率20 kW时, 取样波形无失真, 合成器无明显温升, 满足固态功率源大功率稳定运行的要求。 The principle of design and calculation of the power synthesis in the solid state amplifier are described in this paper. The working frequency of the synthesizer is 80.5 MHz. The output continuous wave power is more than 20 kW; The synthesizer power capacity is analyzed. The theoretical calculation results, Computer Simulation Technology (CST) simulated results are compared with the measured results of the actual 3 dB couplers. The analysis of the measured results and CST calculated results shows that the simulation is in agreement with the measurement results which meet the design requirements of the solid state amplifier. Except the coupling coefficient, the isolation, the VSWR and other parameters are better than the design target. When the output power is 20 kW, the sampling waveform has no deform and the temperature of the synthesizer is stable.     

啁啾脉冲在正常色散光纤中频域特性实验研究

对负啁啾脉冲在正常色散光纤中的频域特性进行了实验研究,并对实验结果进行了数值分析,实验和数值分析结果基本一致．     

LO-phonon effect on the exciton binding energy in polar rectangular quantum wires

Longitudinal optical phonon effect on Wannier excitons in polar rectangular quantum wires is studied by a variational approach. The binding energy is calculated and the numerical results for several II-VI and III-V compound semiconductor rectangular quantum wires are given. The results show that the phonon effect reduces the binding energy and cannot be neglected. The phonon contribution to the binding energy is sensitive to the size of the rectangular quantum wire section, and increases with decreasing section area. The results for the GaAs rectangular quantum wires coincide with the experimental results. The calculated binding energy and the phonon effect in II-VI QWWs are both stronger than those in III-V compound systems, and the results for ZnSe QWW are qualitatively in agreement with the experiments.