共查询到20条相似文献,搜索用时 78 毫秒
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使用Matlab语言得到了迂回位相全息图和博奇型全息图,由傅里叶逆变换得到再现像。阐述了两种计算全息图各自的特点,对再现像的质量、数量、大小、程序运行速度作出对比讨论。迂回位相计算全息图有便于记录、方便传递的特点。利用博奇编码得到的修正离轴参考光计算全息图有高质量的再现像,而且计算速度也比较快,对于复杂的二维图像,可以考虑利用这种编码方法进行计算全息。 相似文献
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通过分析两步法制彩色全息图中全息图空间带宽积与物体大小、全息图记录距离的关系,提出了一种拍摄大尺寸物体彩色全息图的方法。经编码,设置参数,在视窗处平面记录下三分色全息图, 以保证用最小的幅面记录下物体的完整信息,并且H1rgb处于同一平面经原参考光的共轭光再现时,他们的再现像能完全重合;将H1rgb再现,获得大视场的物光波信息,三基色物波信息重合后,用光学方法记录大幅面的彩色全息。该方法能提高全息图再现像的视场和解决大尺寸物体的全息图难拍摄问题。 经实验验证,该方法能将全息图再现像的视场提高6倍左右。 相似文献
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在应用磁共振血管造影图像进行临床诊断时,临床医生往往需要提取感兴趣区域(Region Of Interest,ROI)的部分血管.这个工作传统上需要手工进行,费时费力.该文提出一种并行的血管分割与追踪算法,利用现代图形处理器(Graphics Processing Unit,GPU)所具备的大规模并行计算能力进行快速的血管分割.首先将三维图像网格化为共面的立方体,并行处理每个立方体,确定立方体中哪些表面有血管通过,以及立方体中哪些体素包含血管.之后再将该结果用于串行的全局分割与血管追踪处理.实验结果表明,利用这种先并行后串行的方法,可以在1 s之内完成全脑血管的分割,分割的结果也更准确. 相似文献
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为了简化三维物体计算全息数据和加快计算时间,提出了一种三维点云物体频谱获取方法.在分析频谱获取方法模型的基础上,由不同视角的投影图像(视图)与对应的平面波因子相乘积分的方法得到了三维点云物体频谱;介绍了视图获取算法,使用Matlab并行计算得到了一个三维‘鸟’的视图序列;根据实际物体频谱分布情况,采用高阶高斯概率分布减少视图获取数量;通过视图序列得到三维物体的频谱,采用傅里叶逆变换得到物空间内一个平面的复振幅分布,将其衍射一段距离,编码为菲涅尔全息,并进行了模拟再现和实验验证.模拟再现和实验结果表明:只需要原总视图的17.75%可以获得高质量的再现效果,验证了频谱获取方法的可行性及视图获取简化模型的正确性.所获取的三维物体频谱可以通过一定方式编码成多种全息进行三维显示,拓宽了该频谱获取方法的应用范围. 相似文献
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Chunye Gong Jie Liu Lihua Chi Haowei Huang Jingyue Fang Zhenghu Gong 《Journal of computational physics》2011,230(15):6010-6022
Graphics Processing Unit (GPU), originally developed for real-time, high-definition 3D graphics in computer games, now provides great faculty in solving scientific applications. The basis of particle transport simulation is the time-dependent, multi-group, inhomogeneous Boltzmann transport equation. The numerical solution to the Boltzmann equation involves the discrete ordinates (Sn) method and the procedure of source iteration. In this paper, we present a GPU accelerated simulation of one energy group time-independent deterministic discrete ordinates particle transport in 3D Cartesian geometry (Sweep3D). The performance of the GPU simulations are reported with the simulations of vacuum boundary condition. The discussion of the relative advantages and disadvantages of the GPU implementation, the simulation on multi GPUs, the programming effort and code portability are also reported. The results show that the overall performance speedup of one NVIDIA Tesla M2050 GPU ranges from 2.56 compared with one Intel Xeon X5670 chip to 8.14 compared with one Intel Core Q6600 chip for no flux fixup. The simulation with flux fixup on one M2050 is 1.23 times faster than on one X5670. 相似文献
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三维多群中子扩散方程的精确、高效求解是核动力堆芯设计及燃料管理的基础。应用有限差分方法求解该方程具有简便、精确、成熟的优点;然而,该方法的计算量和存储量均较大,极大地限制了它的计算规模和应用范围。本文基于大规模并行计算,研究三维多群中子扩散方程有限差分方法:采用中心有限差分格式离散中子扩散方程;基于MPI并行编程模型,采用空间区域分解的方式实现大规模并行计算;采用多群多区域耦合PGMRES算法进行并行加速。在集群服务器上开发了ParaFiDi程序,并采用IAEA3D,PHWR等多个基准题对该程序进行验证。数值结果表明,ParaFiDi程序具有较高的计算精度和计算效率。 相似文献
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A computational method based on pure-phase look-up-table (LUT) is proposed for generating kinoforms of full-color real-existing three-dimensional (3D) objects. The principle of the pure-phase LUT method is described. 3D depth as well as color information of a full-color 3D object is obtained by the full-color 3D profile measurement approach based on binocular vision. The obtained full-color 3D data is decomposed into red (R), green (G), and blue (B) channels, and kinoforms of each channel are calculated from the depth map and color information of the corresponding channel using the pure-phase LUT method. In order to reduce the speckle noise of reconstructed full-color 3D image, sequential kinoforms of each color channel are generated by adding dynamic-pseudorandom phase factor into the object domain. Numerical reconstruction and optical reconstruction with a phase-only spatial light modulator (SLM) show that, with the proposed method, full-color holographic 3D display of real-existing full-color 3D objects is available. 相似文献
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三维多群中子扩散方程的精确、高效求解是核动力堆芯设计及燃料管理的基础。应用有限差分方法求解该方程具有简便、精确、成熟的优点;然而,该方法的计算量和存储量均较大,极大地限制了它的计算规模和应用范围。本文基于大规模并行计算,研究三维多群中子扩散方程有限差分方法:采用中心有限差分格式离散中子扩散方程;基于MPI并行编程模型,采用空间区域分解的方式实现大规模并行计算;采用多群多区域耦合PGMRES算法进行并行加速。在集群服务器上开发了ParaFiDi程序,并采用IAEA3D,PHWR等多个基准题对该程序进行验证。数值结果表明,ParaFiDi程序具有较高的计算精度和计算效率。 相似文献
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高Ra数Rayleigh-Bénard热对流的湍流特性研究是当前国际上的一个热门研究课题, DNS模拟计算是研究该课题的重要手段之一. 当计算规模增大而网格数巨大时计算工作难以实现, 高Ra湍流热对流的数值模拟研究面临重大挑战. 本文创建了大规模高效并行计算的三维湍流热对流直接求解方法. 采用FFT变换解耦压力泊松方程, 将其变换成沿z方向上的块三对角方程组, 并利用块三对角方程的MPI与OpenMP联立的大规模高效并行近似解求解方案, 创建了可以高效并行计算的热对流直接求解方法. 通过对该方法并行效率的验证计算, 证明新的直接求解并行计算方法具有很好的并行效率和计算时效. 三维窄方腔热对流的计算结果表明, 本文方法计算的三维热对流特性是合理的. 本文创建的可大规模高效并行计算的三维湍流热对流直接求解方法, 也很可能是关于计算流体力学不可压NS方程大规模高效并行计算在特殊情况中计算技术上的一个突破. 相似文献
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This paper describes two stereo imaging experimental set-ups useful in measuring the 3D geometry of objects: a parallel optical-axis model and a converging optical-axis model. Digital image correlation is used to find the disparities between corresponding points in a pair of images, for each of these models, with subpixel accuracy. To show the application of the developed algorithms and the stereo imaging experimental set-ups, four different body geometries are used. For some of the objects tested a higher measuring accuracy is obtainable from the converging optical-axis experimental set-up. 相似文献
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Optical shadow-casting (OSC) technique has shown excellent potential for optically implementing two-operand parallel logic gates and array logic operations. The 16 logic functions for two binary patterns (variables) are optically realizable in parallel by properly configuring an array of 2×2 light emitting diodes. In this paper, we propose an enhanced OSC technique for implementing four-operand parallel logic gates. The proposed system is capable of performing 216 logic functions by simply programming the switching mode of an array of 4×4 light emitting diodes in the input plane. This leads to an efficient and compact realization scheme when compared to the conventional two-operand OSC system. 相似文献
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Multiview autostereoscopic systems display three-dimensional (3D) images interleaved from parallax images to provide adequate viewing zones for viewers. A 3D image interleaving method based on parallel processing with Graphic Processing Unit (GPU) is proposed to accelerate the image interleaving for real-time autostereoscopic displays. The proposed method is implemented with Direct3D Application Programming Interface (API) library. Masks used to interleave the 3D images are generated according to some particular principles. Both multiple texture blending and alpha blending operations are used to interleave a 3D image. The experiments prove that high interleaving efficiency and good stereoscopic sense can be obtained. The proposed method meets the requirement of real-time multiview autostereoscopic displays and avoids extra shader program. 相似文献