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近红外光早期宫颈癌诊断的频域逆蒙特卡洛光学参量重构研究 被引量:3
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作者 张顺起 侯少华 +2 位作者 赵会娟 周晓青 高峰 《光子学报》 EI CAS CSCD 北大核心 2009年第7期1800-1805,共6页
研究了基于时域蒙特卡洛模拟的频域信息提取方法、光学参量反演方法和提高反演速度的措施.提出了利用离散傅立叶变换(传统法)和改进法两种提取频域信号幅值相位的方法.通过建立一定散射系数范围内的正向MC模拟数据库、采用拟合方法以及... 研究了基于时域蒙特卡洛模拟的频域信息提取方法、光学参量反演方法和提高反演速度的措施.提出了利用离散傅立叶变换(传统法)和改进法两种提取频域信号幅值相位的方法.通过建立一定散射系数范围内的正向MC模拟数据库、采用拟合方法以及利用朗伯-比尔定理,解决了光学参量反演中快速获得MC模拟结果的问题.模拟实验结果表明:改进法无论在反演准确度还是计算时间上均优于传统法,当其中一个参量不变时,散射系数的反演相对误差小于±6%,吸收系数的反演相对误差小于±10%;当吸收和散射系数同时变化时(30<μs<100cm-1,0.2<μa<0.50cm-1),两个参量反演相对误差在±10%以内.采用快速反演技术重构一组光学参量所需要的计算时间小于1分钟. 展开更多
关键词 近红外扩散光 频域 宫颈组织 逆蒙特卡洛模拟 LM优化算法
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Reversal of Magnetisation in Ising Ferromagnet by the Field Having Gradient
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作者 Abyaya Dhar Muktish Acharyya 《Communications in Theoretical Physics》 SCIE CAS CSCD 2016年第11期563-570,共8页
We have studied the reversal of magnetisation in Ising ferromagnet by the field having gradient along a particular direction. We employed the Monte Carlo simulation with Metropolis single spin nip algorithm. The avera... We have studied the reversal of magnetisation in Ising ferromagnet by the field having gradient along a particular direction. We employed the Monte Carlo simulation with Metropolis single spin nip algorithm. The average lifetime of the metastable state was observed to increase with the magnitude of the gradient of applied field. In the high gradient regime, the system was observed to show two distinct region of up and down spins. The interface or the domain wall was observed to move as one increases the gradient. The displacement of the mean position of the interface was observed to increase with the gradient as hyperbolic tangent function. The roughness of the interface was observed to decay exponentially as the gradient increases. The number of spin flip per site was observed to show a discontinuity in the vicinity of the domain wall. The amount of the discontinuity was found to diverge with the system size as a power law fashion with an exponent 5/3. 展开更多
关键词 Ising ferromagnet metastable lifetime Monte Carlo simulation metropolis algorithm
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