diffusion equation

diffusion equation的基本解释

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扩散方程

与diffusion equation相关的网络例句 [注：此内容来源于网络，仅供参考]

objective to obtain the diffusion tensor maps of the normal human brain,and assess intrinstic properties of water diffusion in quantitative parameters for an anatomic analysis.methods maps of isotropic apparent diffusion coefficient and various anisotropic maps were calculated in60healthy adults from seven diffusion imagings by using single-shot echo-planar diffusion-weighted sequence.brain parenchyma anatomy was analyzed and adciso and various anisotropic index were measured.results （1）diffusion properties of different tissues and anatomic areas of normal adult human brain are different.diffusion in white matter is anisotropic;diffusion in gray matter is isotropic.

目的 获取正常人脑组织扩散张力性图像（diffusion densor imaging，dti），定量分析正常人脑组织水扩散的内在特性，进一步评价脑解剖结构。方法 60例健康正常人，应用单次激发epi-dw序列，计算出adciso图及各向异性图，分析脑实质不同区域的解剖结构，测量adciso（isotropic apparent diffusion coefficient）及各向异性指数。结果（1）脑内不同组织结构弥散特性不同，脑白质弥散表现为各向异性，而脑灰质弥散表现为各向同性。

In this topic, the dynamic analysis methods for piezoelectric vibrator are studied systematically based on the theoretical model, FEM numerical experimentation and FEM governing equation for given compound-mode vibrator, and some valuable conclusions are obtained. The main work accomplished is summarized as follows: 1.Elaborate the main modeling methods for piezoelectric vibrator and the significance and necessity to study the dynamic characteristics of piezoelectric vibrator which emphasize the urgency of this paper. 2.Take the bending deformation induced by piezoelectric ceramic as example, the energy transfer mechanism of electric energy to mechanical energy are analyzed; the motion and force transfer mechanism are analyzed for the longitudinal-bending vibrator. 3.Based on mode assumption and Hamilton principle, the coupling model of piezoelectric vibrator of linear USM is built; moreover, the equivalent circuit model is obtained and a coupling equation represents the relation between electric parameters and mechanical parameters is derived which provides foundation to match the vibrator and driving circuit. 4.Combine the constitutive equation of piezoelectric ceramic with elastic-dynamical equation, geometric equation in force field and the Maxwell equation in electric field and the corresponding boundary condition equation, the FEM control equation for piezoelectric vibrator of USM to solve dynamic electro-mechanical coupling field is established by employing the principle of virtual displacement. The equation lays the foundation to study the non-linear constitutive equation of piezoelectric ceramic driven by high-power. 5.Define the dynamic indexes of characteristic of vibrator and carry out variable parameters simulation by calculating the model parameters and the electric characteristics of vibrator are simulated according to the equivalent circuit model. By numerical experimentation, the working mode of vibration of vibrator and the shock excitation results of the working frequency band which provides the mode frequency to realize bimodal are analyzed. Detailed calculation of the electro-mechanical coupling field parameters is made by programming the FEM control equation.

本课题从理论模型、有限元数值试验、有限元控制模型等方面以复合振动模式振子为例对超声电机压电振子的动力学特性及其分析方法进行了全面系统地研究，得出了许多有价值的结论，主要概括如下： 1、阐述了目前针对超声电机压电振子的主要建模方法，对压电振子动态特性的研究意义和必要性进行了论述，突出了本文研究内容的迫切性； 2、以压电陶瓷诱发弹性体发生弯曲变形为例，分析了压电陶瓷通过诱发应变来实现机电能量转换的机理；对基于纵弯模式的压电振子的运动及动力传递机理进行了分析； 3、基于模态假定，利用分析动力学的Hamilton原理，建立了面向直线超声电机压电振子的机电耦合动力学模型，并据此建立了压电振子的等效电路模型，导出了电参量与动力学特性参量的耦合方程，为压电振子与驱动电路的匹配提供了依据； 4、从压电陶瓷的本构方程出发，综合力场的弹性动力学方程、几何方程、电场的麦克斯韦方程以及相应的边界条件方程，采用虚位移原理，建立了压电振子动态问题机电耦合场求解的有限元控制方程，为研究其大功率驱动下的非线性本构模型奠定了基础； 5、界定压电振子的动力学特性指标，对压电振子的机电耦合动力学模型参数进行计算及变参数仿真；依据等效电路模型，对压电振子的电学特性进行了仿真分析；通过有限元数值实验，对压电振子工作模态附近的模态振型及工作频率附近的频段进行了激振效果分析，找出了实现模态简并的激振频率；利用有限元控制方程，通过编程计算，对压电振子的力电耦合场参数进行了详细计算，得出了一些有价值的结论。

Based on the above-mentioned parameter, according to the relationship between robust estimation and nonlinear diffusion, the Turkey loss function is introduced as the diffusion function in SAR image decomposition because of its better performance, and the contour of an image is extracted by the Turkey diffusion function with the proposed diffusion parameter mentioned above. The experiment results indicate that the Turkey loss function based diffusion process can strengthen the conspicuous contour. Additionally, a Raita\'s criterion-based method, solving the automatic diffusion threshold, is proposed to automatically set the threshold in diffusion decomposition.

针对基于梯度参数和局域方差系数的扩散在对SAR图像进行分解时存在的缺陷，提出了一种局域方差系数与窗口幅度均值积的扩散系数，该系数能够更有效地实现潜在目标区域和背景区域的区分；在此基础上，根据鲁棒估计与非线性扩散的联系，引入扩散效果更好的Turkey损失函数作为图像分解中的扩散函数，并结合局域方差系数与窗口幅度均值积的扩散参数来提取图像的轮廓，结果表明：基于Turkey损失函数的扩散过程对特征突出的边缘所起的&强化作用&更加明显；此外，针对扩散分解中的阈值确定问题，提出了一种基于拉依达准则的扩散阈值自动求解方法，实现了扩散阈值的自动求解。

与diffusion equation相关的网络解释 [注：此内容来源于网络，仅供参考]

diffusion equation：扩散方程

本论文提出基于扩散方程(Diffusion Equation)的通用次表面散射模型,用于异质半透明材质的建模、测量以及实时绘制. 模型采用偏微分方程简洁有效地描述了异质半透明物体内部的次表面散射. 基于该模型,论文提出了逆向求解建模算法(Inverse Diffusion Equation),

diffusion equation：扩散方程式

diffusion flame 扩散焰 | diffusion equation 扩散方程式 | diffusion electrode 扩散电极

diffusion equation：拡散方程式

diffusion current 拡散電流 | diffusion equation 拡散方程式 | diffusion kernel 拡散核

diffusion equation：扩散反应式

diffusion coefficient扩散系数 | Diffusion equation扩散反应式 | Diffusion procedures 扩散工艺

convection diffusion equation：对流扩散方程

伯格斯方程Burgers equation | 对流扩散方程convection diffusion equation | 修正微分方程modified differential equation