Experimental versus theoretical robustness of rotating solutions in a parametrically excited pendulum: A dynamical integrity perspective

The objective of this paper is showing how global safety arguments can be fruitfully used to interpret experimental results of a pendulum parametrically excited by wave motion. In fact, the results of an experimental campaign developed with the aim of simulating sea-waves energy production by a parametric pendulum show that rotations exist in a region which is smaller than the theoretical one. This discrepancy can be partially attributed to the experimental approximations and constraints, but it has a deeper theoretical motivation. By comparing the experimental results with the dynamical integrity profiles we have found that experimental rotations exist only where a measure of dynamical integrity accounting for both attractor robustness and basin compactness is large enough, so that they can support experimental imperfections leading to changes in initial conditions.     

Uniformity trials in plant freezing assays involving microtitre plates

The primary aim of this study was to measure the inherent experimental variability in plant freezing assays involving microtitre plates. Laurus nobilis leaf strips were used as experimental material. Data analysis involved variability measurements among and within microtitre plates. Statistically significant variability (p < 0.05) was observed in both cases. The second aim was to test the effectiveness of five experimental designs, in controlling the experimental error. According to our results the variability in microtitre plate freezing assays can be controlled by the use of blocked experimental designs and single well plots.     

利用DISLab定量探究焦耳定律

针对新、旧人教版高中物理教材均缺少对焦耳定律实验探究的问题,利用DISLab设计相应实验内容,并自制配套的实验装置,实验过程操作简单,数据图像清晰明了,实现了对焦耳定律的科学定量探究.     

对风沙输运中起跳沙粒运动状态分布的讨论

本文用Lagrange方法结合起跳沙粒初始运动状态分布模拟了稳态风沙输运过程。根据已有的对地表沙粒撞击起跳现象的研究成果,列出四种典型的沙粒起跳初始运动状态分布形式。将在各分布形式下模拟得到的宏观量与风洞实验测量得到的宏观量的变化规律相比较,通过考察依据各分布形式所作数值模拟得到的风沙宏观运动的特征量与实验测量结果的一致程度,得到了其中较合理的分布形式。分析表明稳定风沙输运中起跳沙粒的初始速度和角度的分布曲线均应为一单调下降曲线,根据实验数据本文构造出由指数分布和正态分布组成的分段函数形式来描述这一曲线。并通过进一步的实验验证了这一分布形式的合理性。     

圆柱空腔内旋转流动中轴对称涡破裂现象的数值模拟

对于上端盖旋转圆柱空腔内旋转流动来说,当流动达到一定条件时,就会出现旋涡破裂现象。目前针对这种现象已经进行了大量的稳态和非稳态实验测量,获得了精确的实验数据。采用数值模拟方法,重现了涡破裂现象及其发生发展过程,同已经发表的相关实验数据进行了比较     

X-ray excited KLL and KLM Auger spectra of manganese

High resolution (ΔE < 1.5 eV) manganese KLL and KLM Auger spectra, obtained by photoexcitation, are persented, and the transition energies and intensities are compared with the experimental and theoretical data published earlier. Significant disagreement can be observed between the respective experimental intensity values in the cases of the most intense lines, and large differences are found between the experimental and the available theoretical transition energy values of the main peaks. The disagreements between the experimental data can be explained rather by the different chemical states of the manganese samples investigated in the separate experiments than by the different mechanisms of the Auger processes.     

基于MATLAB编程的弗兰克-赫兹实验数据处理方法探讨

弗兰克-赫兹实验是理工科近代物理实验教学中的一个重要实验,由于弗兰克-赫兹实验手动测量数据时,所得数据量大而且精度不高,学生人工处理数据的过程中往往面临繁、难等问题.本文提出运用MATLAB GUI的可视化,通过自动读取人工测量实验数据,进行图像拟合,进而使用逐差法和最小二乘法进行数据处理.教学实践表明,该方法不仅能够有效地解决实验数据处理中的繁琐、困难等问题,还能够充分发挥学生的主动性,使学生对实验原理的本质和实验数据的处理有更加深刻的理解和思考,提高物理实验教学的有效性.在教学实践中,使用该方法,不仅有了更多的时间综合训练学生的实验操作能力,同时也提高了实验教学的有效性,创新了传统实验教学的复杂数据处理过程,实验教学效果较佳.     

LED毫伏级待测电动势实验仪的设计及其稳定性的研究

为了满足电位差计实验对毫伏级待测电动势需求,设计了LED毫伏级待测电动势实验仪,并对其稳定性进行了研究.待测电动势实验仪是通过光电转换来实现的,输出的毫伏级电动势在电位差计实验仪的各个测量点都能稳定,能够满足箱式电位差计测量范围和精度要求,是比较理想的箱式电位差计实验配套仪器,能够大大提高学生的实验效率和教师对实验设计的选择性,实验效果良好.     

Combustion kinetic model development using surrogate model similarity method

An ideal combustion kinetic model needs to be validated by different experimental targets over a wide range of temperatures and pressures that represent operating conditions in real engines. However, conditions of laboratory experiments for model validation are often limited by the constraint of experimental techniques. In order to improve model predictions under certain conditions (for example, at a relatively higher pressure), it is often needed to use the experimental data obtained under other conditions. In this work, the surrogate model similarity (SMS) method is proposed to find the experimental conditions or targets for model optimisation under certain conditions where the experiments are hard to be conducted. The similarity coefficient is calculated by the cosine similarity between the characteristic coefficients (vectors) of the High Dimensional Model Representation (HDMR) models for different model predictions. A larger similarity coefficient represents a closer relationship between two model predictions. The experimental data with larger similarity coefficients could be more effective to model uncertainty reduction under the concerned conditions. To demonstrate this method, simulations were conducted for two selected combustion systems with hydrogen or methanol as the fuel. In addition to its strength in available experimental data selection for model optimization, this method can be used to screen out experimental targets with strong constraint effect beforehand, thus providing an effective way to maximise utilisation of experimental resources.     

What can we learn by comparing experimental and theoretical-computational X-ray scattering data?

In this letter we use X-ray scattering data of liquid water, as obtained by different experimental and theoretical-computational procedures, to address the problem of quantitative modeling of the scattering signal in liquids. In particular we investigate the accuracy of well optimized water models in reproducing top level X-ray experimental results and compare experimental data variations with the ones given by different theoretical-computational models. Results show that the experimental scattering data have an intrinsic noise which is comparable to the deviations of the theoretical-computational signals, hence suggesting that no reliable refinement based on scattering data is possible for such models.     

一种实用的多功能的函数拟合程序

研制了函数拟合程序.本程序主要特点在于可键盘或联机输入实验数据.利用计算机图示功能,手动、或自动拟合,以寻求最佳。本系统能打印出拟合后各参数的最佳值。并能在数字绘图仪上分别画出实验数据和理论曲线或光谱分解后的各分立子谱带。     

Adaptive quantum tomography

We provide a review of the experimental and theoretical research in the field of quantum tomography with an emphasis on recently developed adaptive protocols. Several statistical frameworks for adaptive experimental design are discussed. We argue in favor of the Bayesian approach, highlighting both its advantages for a statistical reconstruction of unknown quantum states and processes, and utility for adaptive experimental design. The discussion is supported by an analysis of several recent experimental implementations and numerical recipes.     

中子引起的α粒子发射DDX数据测量进展

从实验的角度对目前国际上测量中子引起的α粒子发射双微分截面的主要研究小组的工作和所使用的两种主要测量谱仪进行了评述．对现阶段的实验进展以及发展趋势作了探讨． The main experimental groups in the world for measuring double-differential cross sections (DDX) of α-particles emission induced by neutron and two kinds of main spectrometers used are reviewed in the point of experimental view. Progress on experimental measurement of DDX in present stage is compared and development trend in future is discussed.     

光学虚拟实验系统研究

采用MATLAB技术,结合光学实验教学内容的特点,利用面向对象的方法开发构建了光学虚拟实验系统。该系统具有操作简单、界面直观、实验快速实施等特点。以空间滤波实验和偏振光实验为例,给出了设计思想和相应的仿真实现结果。学生通过对实验系统的操作,可以很快地掌握实验原理、内容和实验特点。该系统作为传统光学实验教学的补充,能够完成一般光学实验中难以实现的实验操作,使复杂的实验操作变得直观生动,提高了光学实验教学的效果,同时也为相关实验系统的设计研发提供了一条新的途径。     

光电效应测普朗克常数的数据处理及误差分析

在光电效应测量普朗克常数的实验中,采用零电流法测遏止电压,实验操作的可重复性好.不论是采用逐差法还是线性回归法,计算得出普朗克常数的相对误差都在2.5%之下,甚至相对误差小到0.03%,而且通过对该实验数据处理及分析,发现同一次实验数据,用不同的数据处理方法,相对误差竟相差几十倍.     

基于计算机网络技术的实验数据处理系统

系统能够在不需改变程序的情况下,对不同的实验项目均可实现实验预习、演示、实验数据在线检查、自动批阅实验报告等功能。     

基于PROTEUS的李萨如图形观绘实验

针对在传统示波器的使用实验教学过程中学时相对较短、实验操作不规范及实验仪器存在系统误差导致实物实验教学效果不佳的问题,与实物实验相结合,通过Proteus VSM提供的虚拟示波器进行多种频率比与不同相位差情况下的李萨如图形观察实验,可更加直观方便地学习测量正弦振动频率的方法,加深理解互相垂直振动合成理论。这种将实物实验与虚拟仪器实验相结合的实验教学方法,显著改善了示波器的实验教学效果。     

科技与人文融合背景下的中学物理设计型实验的教学研究

针对目前中学物理设计型实验面临的问题,依据理性思维和感性思维相结合、跨学科研究方法相结合的原则,对中学物理设计型实验进行教学改进.通过增加历史上重要物理实验的设计过程、实验的可行性分析、实验结果的分析与修正,丰富教学内容和形式.通过增加设计实验思维过程的多维度科学评价、实验结果分析的评价,完善实验教学评价.以此提高学生开展设计型实验的积极性,促进学生物理知识和实验技能的提升,达到最终提高科学素养的目标.     

Investigating the temperature dependence of elastic constants by thermal fluctuation formula

The differences between the calculated values of elastic constants of materials and the experimental data are consistently restricting the application of thermal fluctuation formula to the mechanical properties of materials. In this work, the temperature dependence of elastic constants of many-body potentials is studied by thermal fluctuation formula. The differences between the calculated values and the experimental data are investigated in detail. Our studies show that the differences come from the thermal expansion of the materials: the calculated zero-stress states are bigger than the experimental zero-stress states of the materials, and this deviation makes Born terms of the thermal fluctuation formula decrease sharply as the temperature increases, while the fluctuation terms and the kinetic terms change little. As a result, the elastic constants, which are the sum of these three terms, decrease faster than the experimental data as the temperature increases. Our studies show that when the experimental zero-stress states are used as the reference states in constant volume and constant energy (NVE) simulations, the elastic constants calculated by thermal fluctuation formula are in good agreement with the experimental values.     

以系列三维立体投影实验为例谈大学物理实验中的创新型人才培养

创新能力是本世纪的核心竞争力,其关键是创新型人才的培养,这为理工类高校的实验教学提出了新的挑战.目前高校中的以学生为主体,教师为主导的大学生创新实验项目的实施是解决此挑战的有效途径之一.以笔者承担的系列三维立体投影物理实验的大学生创新实验项目为例,探讨了大学物理实验中的创新型人才培养模式.通过循序渐进的实验过程,引导学生自主搭建实验装置和编写控制程序,有效培养了学生的创新和实践能力,为高校实验教学改革提供了参考.