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基于连续切片的三维重构技术在材料凝固组织研究中的应用 总被引:1,自引:1,他引:0
讨论了在材料科学与工程研究中进行三维重构的意义和必要性,介绍了基于连续切片的三维重构技术的理论、方法及在材料科学与工程中的研究和应用进展.指出基于切片的三维重构技术对材料凝固过程中微观结构定量分析、微观组织-性能的研究提供了有力支持,结合数值模拟技术可为材料凝固过程中复杂组织的形成机理及凝固理论的发展提供理论和精确的实验依据,从而对新材料的设计与开发产生重要作用.最后简要介绍了三维重构技术在定向凝固过程中多相组织分析的应用,并展望了三维重构技术的发展方向. 相似文献
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讨论了材料科学进行三维重构的意义和必要性,详细介绍了基于三维重构的材料微观结构研究的4个步骤:二维图像的获取、二维图像的处理、三维重构和材料微观结构研究.提出由于基于三维重构的材料微观结构研究材料能够分析出材料的宏观力学性能对微观结构的依赖关系,所以进行基于三维重构的材料微观结构研究方法能够对复合材料的设计提供有力的支持. 相似文献
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采用美国可视人计划(VHP)提供的人体切片图像,对颞骨进行了三维重构.从图片配准、轮廓提取、相邻组织器官公共轮廓线的创建、三维模型的表面光顺等方面介绍了重构过程中涉及到的方法,所建三维模型证明这些方法行之有效,也适用于其他组织器官的重构.三维模型的建立为后续的手术规划、口腔修复和模拟手术等打下了基础. 相似文献
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基于CT切片的三维混凝土细观层次力学建模 总被引:1,自引:0,他引:1
基于CT 切片研究混凝土数值模型的三维重构,可以为揭示混凝土破坏机理研究提供更好的研究对象。基于数字图像技术和MATLAB 图像处理工具,针对混凝土截面CT 切片研究混凝土三维模型的重构技术。应用CT技术获取混凝土试件截面切片,应用底帽变换等方法将CT切片处理为三值图片,考虑孔隙影响,并基于体数据法重构混凝土三维模型。基于网格映射方法,重点研究了单元属性控制因素,提出更精确的单元属性识别判断准则,得到了与试件真实骨料配比相近的三维有限元网格模型。对重构的混凝土试件的四点弯拉断裂过程的非线性有限元分析表明,数值分析的弯拉曲线与破坏形态都与实验结果有较好的相似性,数值模型能较好的模拟实际混凝土试件的破坏。 相似文献
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由于激光雷达获取的深度数据非常稀疏,为了能够将深度数据与图像数据重构出稠密三维深度图,本文提出了基于稀疏激光点云数据和单帧图像融合的三维重构算法。该方法首先使用点直方图特征有效地选择对应于目标的点数据并消除体素中的非相似点;然后,使用高斯过程回归对局部深度数据建模,并通过插值获得三维深度数据,本文算法获得的三维深度点更接近基准值,并保持了目标的局部形状特征;最后,利用马尔科夫随机场对图像灰度数据和三维插值点进行融合来构建三维深度图。仿真实验结果表明:相比现有基于激光雷达数据和单目图像数据的三维重建算法,本文提出的算法将大大提升算法的鲁棒性与重构的准确度,可辅助用于复杂的城市场景中车辆的无人驾驶。 相似文献
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基于相位测量轮廓术的复合光栅优化设计 总被引:2,自引:1,他引:1
基于复合光栅的相位测量轮廓术在物体三维信息重建中是一种非接触、实时的测量方法.通过对这种光栅的形成机理分析,发现当复合光栅中的空间调制光栅的频率一定时,其中相移光栅周期与三维重构精度有关,并且存在一个重构均方差最小值的相移光栅周期,其大小与被测物体的形貌有关.因此,可通过优化复合光栅结构的方法来提高测量精度.利用数字投影仪将连续改变相移光栅周期得到的复合光栅投影到物体,获取变形光栅图像来重建物体的三维信息,从周期数与均方差关系曲线中找到对应的复合光栅的最优化参数,以实现复合光栅最优化设计.通过数字模拟和实验都证实采用优化设计的复合光栅来提高物体的测量精度是有效的. 相似文献
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本文提出了基于数字图像处理和精密机械动作大于光学显微镜观察视野(0.647 min×0.483 mm)的微小物体的三维重构方法.该方法首先运用光学聚焦原理采集不同焦平面上的图像组序列,采用图像拼接算法,拼接出研究对象的整体图像.然后采用图像块分割算法和灰度差分算子对图像序列进行分析.最后结合聚焦合成的叠合算法快速地实现了微小物体的三维重构.实验表明,该方法简单有效,所生成的三维重构效果图提供了微小物体的更加丰富的信息. 相似文献
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A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling. 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue. 相似文献
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O'Brien RS 《Radiation protection dosimetry》2003,105(1-4):95-100
Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides. 相似文献
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Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995. 相似文献
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An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a
rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate
agreement is demonstrated between the derived relations and experimental data. 相似文献
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由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。 相似文献
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V. T. Kornienko 《Strength of Materials》1991,23(7):760-765
The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991. 相似文献
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M. M. Gadenin 《Inorganic Materials》2013,49(15):1352-1356
It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle. 相似文献
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V. T. Bublik A. I. Voronin E. A. Vygovskaya V. F. Ponomarev N. Yu. Tabachkova O. V. Toropova 《Inorganic Materials》2011,47(14):1563-1568
An analysis of anisotropy of the properties of a Bi2Se0.3Te2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal
expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological
fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained
using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied. 相似文献