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  本文關(guān)鍵詞： 粒徑測量 磁納米粒子 磁化曲線 曲線擬合 L-M算法 GlobalSearch算法　出處：《華中科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：本文利用磁性納米粒子的磁化曲線進行粒徑分布測量研究。磁性納米粒子的磁化曲線滿足郎之萬方程,包含著粒子的粒徑分布信息。搭建用于獲得磁性納米粒子磁化曲線的三角波磁場裝置,利用優(yōu)化算法對磁化曲線擬合,得到粒徑分布參數(shù)。磁性納米粒子粒徑分布的研究對其應(yīng)用于濃度成像或者溫度成像等生物醫(yī)學(xué)領(lǐng)域具有重要的意義。首先,假設(shè)磁性納米粒子的粒徑服從對數(shù)正態(tài)分布,對磁化曲線進行離散化處理,得到粒徑測量模型。磁流體中磁性納米粒子的單體和聚集體處于動態(tài)平衡狀態(tài)。在外磁場下,磁性納米粒子的磁化強度由單體和聚集體共同構(gòu)成。由此得到聚集體存在情況下粒子粒徑測量模型。利用優(yōu)化算法對磁化曲線進行擬合,得到磁性納米粒子的粒徑分布。其次,利用三角波磁場裝置準(zhǔn)確地獲取磁性納米粒子的磁化曲線。三角波磁場裝置包括激勵磁場產(chǎn)生、磁場測量和數(shù)據(jù)處理三個功能模塊。其中,激勵磁場產(chǎn)生模塊通過激勵波形預(yù)編輯和PID電流調(diào)節(jié)技術(shù)產(chǎn)生三角波激勵磁場;磁場測量模塊通過檢測采樣電阻上的電壓信號實現(xiàn)激勵磁場的測量,通過兩個反向串聯(lián)的探測線圈實現(xiàn)磁性納米粒子磁化強度的測量;數(shù)據(jù)處理模塊包括背景磁場的抑制、數(shù)據(jù)平均處理、磁化強度波形的重構(gòu)、磁化曲線的獲取幾個方面。最后,利用優(yōu)化算法對磁化曲線進行擬合,得到粒子粒徑分布參數(shù)。最常用的非線性曲線擬合算法是L-M算法。L-M算法是一種局部優(yōu)化算法,不能獲得精確的粒子粒徑分布。對優(yōu)化算法進行改進,采用全局優(yōu)化算法GlobalSearch。GlobalSearch算法的測量結(jié)果非常理想,即使在初始點遠(yuǎn)離最優(yōu)解和樣品濃度未知的情況下。利用SOR-20樣品和SOR-30樣品進行實驗驗證。
[Abstract]:In this paper, the magnetization curve of magnetic nanoparticles is used to measure the particle size distribution, and the magnetization curve of magnetic nanoparticles satisfies the Langzhiwan equation. The triangular wave magnetic field device used to obtain magnetization curve of magnetic nanoparticles was built, and the magnetization curve was fitted by optimization algorithm. The study of particle size distribution of magnetic nanoparticles is of great significance for their application in biomedical fields such as concentration imaging or temperature imaging. First, assuming that the particle size of magnetic nanoparticles is in logarithmic normal distribution, The magnetization curve is discretized and the particle size measurement model is obtained. The monomer and aggregate of magnetic nanoparticles in magnetic fluid are in dynamic equilibrium state. The magnetization of magnetic nanoparticles is composed of monomers and aggregates. The particle size measurement model in the presence of aggregates is obtained. The magnetization curve is fitted by an optimization algorithm, and the particle size distribution of magnetic nanoparticles is obtained. The magnetization curve of magnetic nanoparticles is accurately obtained by using the triangular wave magnetic field device. The triangular wave magnetic field device includes three functional modules: excitation magnetic field generation, magnetic field measurement and data processing. The excitation magnetic field generation module generates the triangular wave excitation magnetic field by the pre-editing of the excitation waveform and the PID current regulation technology, and the magnetic field measurement module realizes the measurement of the excitation magnetic field by detecting the voltage signal on the sample resistor. The magnetization of magnetic nanoparticles is measured by two reverse series detection coils. The data processing module includes the suppression of background magnetic field, the average processing of data, the reconstruction of magnetization waveform and the acquisition of magnetization curve. The parameters of particle size distribution are obtained by fitting the magnetization curve with optimization algorithm. The most commonly used nonlinear curve fitting algorithm is L-M algorithm. L-M algorithm is a local optimization algorithm. The particle size distribution can not be obtained accurately. The optimization algorithm is improved, and the global optimization algorithm GlobalSearch.GlobalSearch algorithm is used to measure the results very well. Even if the initial point is far from the optimal solution and the concentration of the sample is unknown, the SOR-20 sample and the SOR-30 sample are used for experimental verification.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TM27;TB383.1

【參考文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前2條

1 鐘景;磁流體熱動力學(xué)行為的磁學(xué)表征[D];華中科技大學(xué);2012年

2 李寅;基于磁納米交流磁化強度諧波測量的若干算法研究[D];華中科技大學(xué);2013年

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本文編號：1530847