创新性模拟海市蜃楼现象

利用定影粉配制成浓度连续变化的溶液,来模拟大气中密度连续变化的空气,实验获得了良好的海市蜃楼"上现蜃景"效果;另外,用不同浓度的蔗糖溶液配制成的梯度溶液,实现了"两个上现蜃景"的效果。通过对这两种体系的成像效果的研究,加深了对海市蜃楼这一神秘自然景观的认识和理解。     

在COIL中BHP的HO2-浓度对氯的利用率和激光功率的影响

对COIL中碱性过氧化氢(BHP)溶液中的HO2-浓度进行了理论计算和实验测量,得到了HO2-浓度随不同浓度的KOH和H2O2以及不同比例(体积)配比的变化规律,并做了不同浓度HO2-对氯的利用率和激光输出功率影响的实验,获得的结果对优化BHP的配制和优化实验参数有较大的意义.     

在“球面附加压强实验”中溶液的配制

在讲球形液面的附加压强时,一个典型的实验如下图所示。在管子两端吹大小不等的两个肥皂泡,当中间活塞打开,两泡相通时,我们将会看到,大泡不断变大,小泡越来越小。此实验对理解Laplace公式是很有帮助的,但其成败的关键是所吹的肥皂泡要足够大,且能保持较长的时间。为达到此目的,我们对溶液的配制进行了探讨。我们用蒸馏水配制同浓度的合成洗涤剂     

乳化技术-火焰原子吸收光谱法测定原油中的铁镍

以Triton X-100为乳化剂将样品的甲基异丁基酮－二甲苯溶液乳化成乳浊液，以聚异丁烯空白溶液为参比，用标准加入法测定。建立了乳化技术－火焰原子吸收光谱法测定原油中铁、镍的快速分析方法。提出了配制空白溶液的原理及方法，对溶剂及乳化剂的选择、空白溶液的配制进行了考察，测定结果与灰化法一致。     

在COIL中BHP的HO2^-浓度对氯的利用率和激光功率的影响

对COIL中碱性过氧化氢(BHP)溶液中的HO2^-浓度进行了理论计算和实验测量。得到了HO2^-浓度随不同浓度的KOH和H2O2以及不同比例(体积)配比的变化规律,并做了不同浓度HO2^-对氯的利用率和激光输出功率影响的实验,获得的结果对优化BHP的配制和优化实验参数有较大的意义。     

演示激光光路的一种方法

演示激光光路的一种方法在液体中得到清晰的光路需满足两个条件，溶液的透明度要好；悬浮在溶液中的颗粒体积小且数量不能过少．采用淀粉胶体溶液做这个实验，效果非常明显．胶体是一种透明液体，且具有丁达尔现象．溶液配制方法：在１００ｍｌ水中加１—３ｇ淀粉，加热搅...     

D-葡萄糖溶液变旋规律的研究

测定了新配制的不同浓度的葡萄糖溶液的比旋光度,分析了溶液的变旋现象,进而研究旋光度变化与时间之间的规律,结果显示溶液比旋光度随时间呈指数变化,并最终达到稳定.     

基于SPR传感器检测的教学实践

基于Kretschmann棱镜模型设计了SPR传感器实验平台,其中传感薄膜由科研实验室制备提供,光路由学生自主搭建,利用医用葡萄糖配制样品溶液,检测其SPR光谱,模拟重金属检测实验,该教学实践实现了科学研究与近代物理实验教学的结合,培养学生的科学兴趣,提高学生的科技创新能力,有助于跨专业、跨领域知识的联系和交流。     

化学氧碘激光器的BHP配制及稳定操作

 作为化学氧碘激光器(COIL)的能量来源，O₂(¹Δ)发生器（SOG）工作状态直接影响COIL的工作性能，而碱性过氧化氢溶液的稳定与否又影响SOG的工作状态。通过对转盘式SOG实验中BHP配制及稳定操作的系统研究，提出了造成BHP溶液不稳定的几种原因及相关的解决方法。     

离子扩散演示仪

利用激光在梯度溶液中弯曲传播的性质,制作了离子扩散演示仪.在该仪器中配制梯度溶液,可观察激光在梯度溶液中的曲线传播,演示海市蜃楼现象,揭示光的折射率与溶液浓度之间的关系.通过梯度溶液上表面位置的变化,可以定量反映溶液中离子扩散的快慢,定量测量离子的扩散系数.     

MKdV方程的拟小波解

用拟小波方法求MKdV方程的数值解-先用拟小波离散格式离散空间导数，然后用四阶Runge-Kutta方法离散时间导数,对一个有精确解的实例ut+6u2ux+uxxx=0进行了数值计算-拟小波解与解析解完全重合，t=10000s时，二者也没有偏差- 关键词： MKdV方程 拟小波方法 孤子解     

Sense and nonsense in the renormalization-scheme-dependence problem

I discuss in detail the issues involved in the renormalization-scheme-dependence problem in perturbative QCD. The problem is not to find a good universal scheme; nor is it a question of how to make coefficients small. The problem is that finite-order results depend on the choice of scheme, even though it is “arbitrary” (in that the exact result is scheme independent). Only the “principle of minimal sensitivity” approach gets to the heart of the problem, and attempts to reconcile this contradiction. I explain the motivation for this approach, defend it against recent criticisms, and explain to what extent it provides a solution to the problem.     

Time adaptive variational integrators: A space-time geodesic approach

The goal of this paper is to show that the space-time geodesic approach of classical mechanics can be used to generate a time adaptive variational integration scheme. The only assumption we make is that the Lagrangian for the system is in a separable form. The geometric structure which is preserved in the integration scheme is made explicit and the algorithm is illustrated with simulation for a compact case, a non-compact case, a chaotic system which arises as a perturbation of an integrable system and the figure eight solution for a three body problem.     

次声波在平流层波导中传播的数值模拟

对次声波在大气中传播进行了建模。通过结合保色散关系空间差分格式和Runge-Kutta时间格式的数值方法,建立了次声波传播模型。应用该次声波模型,研究了在耗散的重力分层大气中次声波的平流层导行传播。数值模拟结果表明,当次声波波包在平流层高度上被反射时,反射区域存在焦散现象,在声波的声压下降的同时,声波的能量得到聚焦。通过数值模拟结果与射线计算结果的对比表明,大气中声波传播的轨迹的精确描述需要应用全波解。      

Theoretical derivation and simulation of a versatile electrostatic trap for cold polar molecules

We propose a versatile electrostatic trap scheme using several charged spherical electrodes and a bias electric held.We hrst give the two-ball scheme and derive the analytical solution of the electric held.In order to make a comparison,we also give the numerical solution calculated by the hnite element software(Ansoft Maxwell).Considering the loading of cold polar molecules into the trap,we give the three-ball scheme.We hrst give the analytical and numerical solutions of the distribution of the electric held.Then we simulate the dynamic process of the loading and trapping cold molecules using the classical Monte Carlo method.We analyze the influence of the velocity of the incident molecular beam and the loading time on the loading efficiency.After that,we give the temperature of the trapped cold molecules.Our study shows that the loading efficiency can reach 82%,and the corresponding temperature of the trapped molecules is about 24.6 mK.At last,we show that the single well divides into two ones by increasing the bias electric held or decreasing the voltages applied to the spherical electrodes.     

带有垂直裂缝定压油气藏模型的数值解

压裂作为低渗油气藏开发和油田增产的措施之一,被油田广泛应用.为使压裂方案经济合理,达到少投入多产出的目的,并提高压裂设计水平,我们对油气藏定压生产条件下压裂井产量预测的数学模型进行了数值求解,指出了各种模型的适用条件和要考虑的因素.本文主要介绍区域有裂缝存在、系数还依赖未知函数的非线性抛物型油气藏方程的数值求解。     

A multistep flux-corrected transport scheme

A multistep flux-corrected transport (MFCT) scheme is developed to achieve conservative and monotonic tracer transports for multistep dynamical cores. MFCT extends Zalesak two-time level scheme to any multistep time-differencing schemes by including multiple high-order fluxes in the antidiffusive flux, while computing the two-time level low-order monotone solution. The multistep time-differencing scheme used in this study is the third-order Adams–Bashforth (AB3) scheme implemented in a finite-volume icosahedral shallow-water model. The accuracy of AB3 MFCT is quantified by the shape-preserving advection experiments in non-divergent flow, as well as a cosine bell whose shape changes during advection in shear flow. AB3 MFCT has been shown to be insensitive to time step size. This make AB3 MFCT an attractive transport scheme for explicit high resolution model applications with small time step. MFCT is tested in shallow-water model simulations to demonstrate that the use of MFCT maintains positive-definite tracer transport, while at the same time conserving both fluid mass and tracer mass within round-off errors in the AB3 dynamic core.     

A Novel Three-Dimensional Wide-Angle Beam Propagation Method Based on Split-Step Fast Fourier Transform

A novel three-dimensional wide-angle beam propagation method based on the split-step fast Fourier transform is developed. The formulation is based on the three-dimensional Helmholtz wave equation. Each propagation step is performed by utilizing both the FFT and split-step scheme. The solution of Helmholtz wave equation does not make the slowly varying envelope and one-way propagation approximations. To validate the efficiency and accuracy, numerical results for a propagation beam in a tilted step-index optical waveguide are compared with other beam propagation algorithms.     

An efficient scheme for optimizing channel utilization in OBS networks

Optical burst switching (OBS) is an emerging technology that allows variable size data bursts to be transported directly over DWDM links. In order to make OBS a viable solution, the wavelength scheduling algorithms need to be able to utilize the available wavelengths efficiently, while being able to operate fast enough to keep up with the burst incoming rate. Unfortunately, horizon scheduling cannot utilize the voids created by previously scheduled bursts, resulting in low bandwidth utilization. To date, Min-SV is the fastest scheduling algorithm that can schedule wavelengths efficiently. However, its complexity is O (log m) and it requires 10 log (m) memory accesses to schedule a single burst. This means that it can take upto several microseconds for each burst request, which is still too slow to make it a practical solution for OBS deployment. In this paper, an efficient scheme has been proposed for optimizing channel utilization in OBS networks. In the proposed approach, a burst is represented by an interval of time. The process of scheduling a number of bursts, thus, turns to be a process of fitting a set of the corresponding time intervals on a channel time line that represents a channel-time resource. By doing so, the scheduling process can be formulated as a combinatorial optimization problem. Then, graph theory is applied to schedule as many non-overlapping intervals as possible onto the channel time line. The underlying concept of the proposed scheduling scheme is that of briefly delaying the scheduling of a burst so that a much better decision can be made about a number of bursts all-together. This scheme is shown, through simulations, to improve performance in terms of burst loss probability, channel utilization, fairness-control and data throughput over existing schemes. Thus the proposed scheme is well suited for high performance networks in terms of reliability.     

Non-paraxial Split-step Finite-difference Method for Beam Propagation

A method based on symmetrized splitting of the propagation operator in the finite difference scheme for non-paraxial beam propagation is presented. The formulation allows the solution of the second order scalar wave equation without having to make the slowly varying envelope and one-way propagation approximations. The method is highly accurate and numerically efficient. Unlike most Padé approximant based methods, it is non-iterative in nature and requires less computation. The method can be used for bi-directional propagation as well.