共查询到20条相似文献,搜索用时 192 毫秒
1.
2.
3.
将第一性原理计算和Monte Carlo算法耦合,对共掺杂稀磁半导体进行模拟,预测其磁学性质,并与同种过渡金属原子单掺杂稀磁半导体相比较进行分析.首先用第一性原理计算掺杂原子间的磁相互作用强度,作为后面Monte Carlo模拟的输入参数;然后利用Monte Carlo方法结合海森堡自旋模型和磁相互作用强度来模拟体系热力学磁化强度和磁化率,由此得到居里温度;用同样的方法模拟掺杂磁性体系的磁滞回线.计算结果显示,对应于掺Co、Al-Co、Fe、Al-Fe的ZnO基稀磁半导体的居里温度分别为346 K、450 K、743 K、467 K,与实验值很吻合;模拟这四种掺杂情况得到的磁滞回线也很符合理论分析和实验结果,且呈现和居里温度相同的变化规律. 相似文献
4.
强荧光背景环境中荧光涨落谱--蒙特卡罗模拟研究 总被引:1,自引:1,他引:0
荧光涨落谱方法(Fluorescence Fluctuation Spectroscopy)通过分析微小探测区域内的荧光涨落信号,获得粒子亮度、扩散系数以及溶液浓度等信息。利用Monte Carlo模拟方法,研究了溶液中自荧光背景和系统噪声对荧光涨落谱的影响。结果表明,利用双组分光子计数统计方法,可以有效去除低亮度、高浓度背景组分自荧光和均匀分布系统噪声产生的影响。本结果为利用荧光涨落谱方法测量细胞体系复杂环境中的蛋白质相互作用提供帮助。 相似文献
5.
6.
7.
Monte Carlo方法研究支气管组织自体荧光光谱 总被引:1,自引:0,他引:1
在实验获得支气管组织显微荧光特性和有关光学特性参量的基础上,将支气管组织简化为三层光学模型,用Monte Carlo方法模拟442nm He-Cd激光在组织模型中的光分布及自体荧光的逃逸函数,计算出各组织层对总体自体荧光的贡献,并模拟出逃逸到组织体表面的自体荧光光谱.进一步实验测量与理论计算的自体荧光光谱比较表明,两者在460~520nm及600~700nm的光谱范围内符合得较好. 相似文献
8.
应用梯度法和Monte Carlo方法对固体推进剂燃烧产物平衡组分进行了计算。比较其优缺点,提出了一种新的算法:梯度-Monte Carlo法。计算表明,无论从机时和精度都可得到满意的结果。 相似文献
9.
通用动力学方程通过描述离散系统中颗粒尺度分布的演变过程来量化颗粒动力学演变过程,而Monte Carlo(MC)算法是求解通用动力学方程的重要方法.目前几种主流的MC算法为Liffman的直接模拟Monte Carlo算法(DSMC)、阶梯式常体积法、常数目法和多重Monte Carlo(MMC)算法.利用这些MC算法描述理想的纯凝并工况和纯破碎工况,发现:由于避免了多个动力学事件之间的解耦过程,基于事件驱动的MC算法比基于时间驱动的MC算法具有更高的计算精度和更低的计算代价;由于尽量减少对整体系统的扰动,阶梯式恢复模拟颗粒数目的MC算法比连续式恢复模拟颗粒数目的MC算法具有更高的精度;由于始终保持计算区域体积,多重Monte Carlo算法具有更友好的扩展性. 相似文献
10.
Monte Carlo方法已被广泛用于模拟复杂的随机介质如生物组织中光的辐射传输.在生物光子应用中,早期的Monte Carlo模拟模型忽略了光在组织中传输的波动性,而用中性粒子光子包来模拟其传播过程.然而,许多光学诊断技术是基于光在组织中的偏振效应和多重散射的相干性来揭示组织的生理和病理信息,这就要涉及光辐射的波动性.本文阐述了用Monte Carlo方法模拟光在生物组织中传播的最新进展. 相似文献
11.
研究了激发光增强时其对荧光关联谱(FCS)测量的影响. 强激发光产生的饱和激发会改 变激光诱导荧光的空间分布函数,从而影响FCS的测量结果. 首先根据饱和吸收的物理模型,推导出强激发光情况下有效探测区域变化的定量公式,获得了FCS测量所得到的粒子数和扩散时间与饱和激发光强和激光光强的函数关系,并用于消除饱和吸收造成的系统误差.采用Monte-Carlo模拟方法和实验,对理论分析结果进行了验证. 这将有助于完善FCS分析方法的理论模型,为高激发光强度下的FCS探测提供依据.
关键词:
荧光关联谱
饱和激发
Monte-Carlo模拟 相似文献
12.
基于靶面温度分布测量反演激光强度时空分布的重构表达式中,被积函数包含的奇异阿贝尔核函数导致了求解积分表达式的病态和解的不稳定。为了解决这一积分求解问题,基于广义函数理论和正则变换方法,对积分函数进行了重新构造,获得了基于靶面温度时空分布测量反演入射激光强度分布的重构算法,并分析了重构结果对温度测量误差的敏感性。借助数值模拟方法对重构算法进行了验证,数值计算给出了重构强度误差与靶板厚度和辐照时间的关系。验证结果表明,两种背光面边界条件下反演获得的激光束时空分布,不仅与原始模型激光束达到了较好的一致,而且不受薄板条件的限制。算法对强激光辐照效应的靶面激光参量监测有实用性。 相似文献
13.
Diffusion dynamics of gold nanoparticles (GNPs) was studied by fluorescence correlation spectroscopy (FCS). The fluorescence was studied by exciting the particles by green laser (532 nm), which is far from longitudinal plasmon band of nanorods. Transmission electron microscope (TEM) and UV-Vis-NIR spectrometer were used to characterize the gold nanoparticles. Despite their low quantum yields, GNPs possess the native fluorescence. The excellent antiphotobleaching behavior of gold nanorods leads to prospects of using FCS for its detailed studies. Using FCS, dynamic information can be extracted from the fluorescence fluctuations in the system by autocorrelation function. Maximum entropy method (MEMFCS) was used to identify the number of distinct components present in the system. The particle sizes obtained from FCS were found to be higher (by few orders of magnitude) compared to TEM analysis. This might be due to the possible contributions from cetyltrimethyl ammonium bromide (CTAB) capping in the system. 相似文献
14.
利用光电流模型研究了气体辐射太赫兹波产额与驱动激光峰值强度的依赖关系.模拟表明,无论是单色激光脉冲还是双色激光场,当激光较弱时,太赫兹产额随着激光强度的增加而迅速增大;而当气体电离接近或达到饱和后,进一步增强激光场强度,太赫兹产额出现了振荡变化.与通常采用较弱激光强度相比,更高的激光强度(致使气体达到完全电离)会进一步增强太赫兹波的辐射强度.分析各个电离事件所产生电子的个数和运动轨迹的对称性,可以很好地解释这些结果. 相似文献
15.
线结构光视觉测量系统是激光扫描测头的重要组成部分,为了提高激光扫描测头的测量精度及可靠性,提出一种线结构光视觉系统结构参数优化设计方法。分析了影响该测量系统整体测量精度的因素以及该测量系统的结构误差模型,并建立了应用于激光扫描测头的结构约束条件,通过该约束条件建立了结构参数优化仿真系统,进而得到仿真优化后的结构参数,即最优结构参数,并设计实测实验验证其合理性。测得优化后的线结构光视觉系统测量空间点间距相对误差为0.019 8 mm,本文结果表明优化方法的有效性,并具有较好的精度。 相似文献
16.
The effect of thermal-induced Brownian motion on gold nanoparticles (Au NPs) in optical traps is studied by fluorescence correlation
spectroscopy (FCS) method. The Brownian motion and optical trapping potential are investigated by the decay time of the FCS
curve and the laser power. It is shown that that the probability of finding a gold nanoparticle in the trap depends on the ratio of the optical energy of the particle to
its thermal energy. A power threshold is observed by the decay time as a function of laser power. The experimental studies
show that the temperature rise does not seriously affect the average number of particles in the focal spot, but the average
residence time is more sensitively affected by the temperature. 相似文献
17.
18.
We propose a physics method to study the effect of laser field and mechanical force on the melting process of double-stranded deoxyribonucleic acid (DNA). A two-dimensional lattice model is established for DNA molecules stuck on the surface, and the stretching energy of the hydrogen bond and stacking energy for each DNA molecule are calculated by using a nonlinear potential. A real-time algorithm is employed to deal with the dynamics process of DNA melting. Numerical results explain the experimental observations. The spatial distribution of the laser field determines the sequences of DNA melting. The simulation has shown the dependence of the final number of melted DNA on the laser field and mechanical force. 相似文献
19.
A set of moment relations, which can describe the charged fluids response to an intense pump laser, and a linearization substitution relation, which is more appropriate as compared with the past treatment, are given by theoretical analyses. The relevant equations of state (adiabatic and isothermal), momentum and energy equations are derived self-consistently.The dispersion relations of the electron plasma wave and the ion acoustic wave driven by an intense pump laser field are-obtained. The results show that the frequencies of both the excited electron plasma wave and the excited ion acoustic wave have a great modification in the case of strong pump. The former bears out the theoretical result obtained from Vlasov equation and the later is consistent with experimental observations. It is proved that the zero-frequency component of the laser light wave contribution to the plasma pressure tensor is un-neglected,which implies a greatly change to the wave excitation properties, particularly in the direction of parallel or approximately parallel to the laser field vector. 相似文献
20.
在激光烧结石墨烯增强铜基复合材料的过程中,了解瞬时温度场分布对优化工艺参数、控制烧结质量有重要作用。建立了激光烧结预涂在42CrMo基板上的石墨烯铜的混合粉末的有限元模型。研究了激光烧结过程温度场分布,熔池的几何参数以及烧结层与基体的冶金结合宽度。为了验证模拟结果,使用与模拟相同的参数进行了单道激光烧结的实验。研究表明,热传导、热辐射和相变潜热在激光烧结过程的温度场分布中起重要作用。实验结果与模拟结果较为一致。所以可以依据模拟结果预测实验的温度场分布和熔池几何参数,同时也可以据此优化激光烧结参数。 相似文献