共查询到20条相似文献，搜索用时 203 毫秒
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<正>本文开展了提高低序级断层成像精度技术研究,以S油田C13区块地震资料为主要研究区块,针对采集处理过程中影响低序级断层识别的观测系统面元网格、信噪比、频率、速度等因素进行探讨分析,研究其产生的机理,结合该区块资料特点,重点针对面元网格、信噪比、频率、速度因素对低序级断层成像精度的影响,进行了深入研究和分析,提出针对性处理技术和方法。 相似文献
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CLIQUE是一种基于密度和基于网格的混合聚类方法。在高维空间中,它能够有效地进行聚类,并且能够发现嵌套在高维数据空间子空间中的聚类。但是,CLIQUE算法存在着很多的局限性,主要有以下两点:首先是子空间的剪枝;其次是CLIQUE算法追求方法简单化。针对CLIQUE算法的局限性,采用基于约束条件的聚类技术、自适应网格技术和边界调整技术来对CLIQUE算法进行改进,提出了基于约束条件和自适应网格的CAG-CLIQUE算法。 相似文献
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分析了现有断层建模技术,提出了基于局部克里金插值算法的横断层自动分析和显示技术。算法通过搜索遍历钻孔点计算模型的有效区域和阈值,选用基于面模型的网格三角化法构建地质体,结合OpenGL实现了三维构建和漫游。实验证明,该方法能够实现横断层的自动分析和显示。 相似文献
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随着生物医学的发展,对生物成像技术和成像分辨率的要求越来越高,纳米材料和技术被越来越多地应用到生物医学领域.各向异性的金纳米棒由于具有较高的电子密度、较大的吸收截面、特殊的表面等离子共振光学特性、优良的生物相容性和化学稳定性而被广泛应用于生物成像领域.本文结合本课题组在该领域的研究经验,综述了金纳米棒的制备方法、光学性能和表面修饰方法;并从金纳米棒局部等离子共振特性出发,综述了金纳米棒的暗场散射成像、双光子荧光成像、光声断层成像、光学相干断层扫描、X射线计算机断层扫描、表面增强拉曼散射成像等生物成像技术.同时阐述了金纳米棒在生物成像、医学诊断和联合治疗等领域中的应用进展. 相似文献
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主要介绍了半导体器件模拟中的几种物理模型和三角形网格自适应划分的算法。并以泊松方程为例,介绍了如何在网格中进行方程的离散化,以及后期计算方程组的几种数值方法并比较各种算法的优缺点,同时得到解的示意图。 相似文献
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In this paper, we first develop an adaptive shifted Legendre–Gauss (ShLG) pseudospectral method for solving constrained linear time-delay optimal control problems. The delays in the problems are on the state and/or on the control input. By dividing the domain of the problem into a uniform mesh based on the delay terms, the constrained linear time-delay optimal control problem is reduced to a quadratic programming problem. Next, we extend the application of the adaptive ShLG pseudospectral method to nonlinear problems through quasilinearization. Using this scheme, the constrained nonlinear time-delay optimal control problem is replaced with a sequence of constrained linear-quadratic sub-problems whose solutions converge to the solution of the original nonlinear problem. The method is called the iterative-adaptive ShLG pseudospectral method. One of the most important advantages of the proposed method lies in the case with which nonsmooth optimal controls can be computed when inequality constraints and terminal constraints on the state vector are imposed. Moreover, a comparison is made with optimal solutions obtained analytically and/or other numerical methods in the literature to demonstrate the applicability and accuracy of the proposed methods. 相似文献
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Gea O. F. Parikesit Jeffrey S. Guasto Salvatore Girardo Elisa Mele Ripalta Stabile Dario Pisignano Ralph Lindken Jerry Westerweel 《Biomicrofluidics》2009,3(4)
Nanoparticle image velocimetry (nano-PIV), based on total internal reflection fluorescent microscopy, is very useful to investigate fluid flows within ∼100 nm from a surface; but so far it has only been applied to flow over smooth surfaces. Here we show that it can also be applied to flow over a topologically structured surface, provided that the surface structures can be carefully configured not to disrupt the evanescent-wave illumination. We apply nano-PIV to quantify the flow velocity distribution over a polydimethylsiloxane surface, with a periodic gratinglike structure (with 215 nm height and 2 μm period) fabricated using our customized multilevel lithography method. The measured tracer displacement data are in good agreement with the computed theoretical values. These results demonstrate new possibilities to study the interactions between fluid flow and topologically structured surfaces. 相似文献
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BackgroundReconstruction of customized cranial implants with a mesh structure using computer-assisted design and additive manufacturing improves the implant design, surgical planning, defect evaluation, implant-tissue interaction and surgeon's accuracy. The objective of this study is to design, develop and fabricate cranial implant with mechanical properties closer to that of bone and drastically decreases the implant failure and to improve the esthetic outcome in cranial surgery with precision fitting for a better quality of life. A customized cranial mesh implant is designed digitally, based on the Digital Imaging and Communication in Medicine files and fabricated using state of the Art-Electron Beam Melting an Additive Manufacturing technology. The EBM produced titanium implant was evaluated based on their mechanical strength and structural characterization.ResultsThe result shows, the produced mesh implants have a high permeability of bone ingrowth with its reduced weight and modulus of elasticity closer to that the natural bone thus reducing the stress shielding effect. Scanning electron microscope and micro-computed tomography (CT) scanning confirms, that the produced cranial implant has a highly regular pattern of the porous structure with interconnected channels without any internal defect and voids.ConclusionsThe study reveals that the use of mesh implants in cranial reconstruction satisfies the need of lighter implants with an adequate mechanical strength, thus restoring better functionality and esthetic outcomes for the patients. 相似文献
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优质信息传播是社交应用持续健康发展的助推力,而适应性信息分享是提高社交信息质量的有效途径。本研究基于认知转变视角和动机二阶模型,构建微信用户适应性信息分享行为的影响因素研究模型,并通过实证研究方法对模型的适用性进行检验。结果表明：动机、他人的使用和差异对微信用户适应性信息分享行为产生显著的正向影响,系统环境的改变和强制使用的影响不显著。形象、社交动机、挑战动机、自我效能和求知动机是微信用户适应性信息分享动机的五大维度。 相似文献
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Moving mesh partial differential equations have been widely used in the last decade for solving differential equations exhibiting large solution variations such as shock waves and boundary layers.In this paper, we have applied a dynamic adaptive method for solving time-dependent differential equations. The mesh velocities are governed by an equation in which a relaxation time is employed to move nodes in such a way that they remain concentrated in regions of rapid variation of the solution. A numerical example involving a blow-up problem shows the advantage of using a variable relaxation time over a fixed one. 相似文献
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In this paper, we have proposed a robust super-resolution high-frequency component estimation (RS-HFCE) method, which can efficiently estimate lost high-frequency components and correct aliasing effects of low-frequency components of an image. The fundamental principle of operation of the proposed method is based on the idea that, when a baseband band-limited image signal of known bandwidth in a high-resolution lattice is iteratively low-pass filtered in the frequency domain, the unknown values in the lattice can be interpolated, thus correcting the aliasing for the low-frequency components. If this process is done along with adjusting the amplitudes of the known pixel values, some high-frequency components of an image are automatically extrapolated. In order to provide simultaneous edge preservation and noise removal capabilities of the super-resolved images, an improved version of an adaptive Perona–Malik (PM) model is incorporated into the process. One of the characteristics of the proposed method is its high level of tolerance capabilities to reconstruction errors and noise caused by an increase in the reconstruction scaling factors. High quality images of higher resolution are still appreciably reconstructed when greater magnification factors are used. From a couple of experiments on real images, and using both subjective and objective image quality assessment measures, it is demonstrated that the proposed method outperforms most of other classical methods. 相似文献
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The augmented Lagrangian strategy has recently emerged as an important methodology for image processing problems. In this paper, based on this strategy, we propose a new projected gradient algorithm for image deblurring with total bounded variation regularization. The convergence property of our algorithm is discussed. Numerical experiments show that the proposed algorithm can yield better visual quality than the Rudin–Osher–Fatemi (ROF) method and the split Bregman iteration method. 相似文献
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提出一种基于游程统计和Walsh谱能量分布的调色板图像隐写分析方法,利用调色板颜色的奇偶值(parity value,P值)构造P值图像,通过游程统计和Walsh变换提取出46维特征,并用校准技术削弱载体图像差异对分析统计量的干扰.实验表明,该方法适用于EzStego、分量和以及最佳奇偶隐写等调色板图像隐写算法,比奇异颜色分析准确. 相似文献