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三维傅立叶变换建立氢原子图像
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作者 宋敬江 《南昌大学学报(理科版)》 CAS 北大核心 2002年第4期345-348,共4页
收集水样品到静磁场和射频磁场作用后 ,每一个自由感应衰减信号 ,并对其进行三维傅立叶变换 ,建立一个数据矩阵 ,矩阵的每个矩阵元由对应的氢原子图像像素决定。
关键词 氢原子图像 三维傅立叶变换 磁共振成像 图像矩阵 像素 三维重建
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三维空间大气紊流场生成与扩展方法 被引量:3
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作者 高振兴 顾宏斌 刘晖 《交通运输工程学报》 EI CSCD 北大核心 2008年第4期25-29,共5页
为了提高飞机穿越大气紊流场时的实时飞行仿真逼真度,提出了三维空间大气紊流场的生成与扩展方法。采用Von Karman模型,在频域空间直接进行蒙特卡罗法随机抽样,经三维傅立叶逆变换得到三维空间大气紊流场。基于傅立叶变换的复共轭对称特... 为了提高飞机穿越大气紊流场时的实时飞行仿真逼真度,提出了三维空间大气紊流场的生成与扩展方法。采用Von Karman模型,在频域空间直接进行蒙特卡罗法随机抽样,经三维傅立叶逆变换得到三维空间大气紊流场。基于傅立叶变换的复共轭对称特性,生成实的紊流场。在飞行仿真过程中,对预先生成的无因次紊流场进行有因次化,保证紊流场尺度和强度随飞行高度动态变化。运用基于对称扩展的紊流场扩展方法,保证生成的局部空间紊流场有效扩展为大范围连续紊流场。仿真结果表明:生成的三维紊流场在对称扩展前、后均符合Von Karman模型,且与基于紊流场相关函数矩阵的生成方法相比,新算法计算速度快,存储空间需求少,更适于实时飞行仿真。 展开更多
关键词 飞行动力学 大气紊流场 蒙特卡罗法 三维傅立叶变换 紊流场生成 紊流场扩展
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Study on three dimensional electromagnetic model for permanent magnet linear synchronous motor 被引量:2
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作者 汪旭东 王兆安 袁世鹰 《Journal of Coal Science & Engineering(China)》 2002年第1期87-90,共4页
In this paper, with the non-salient pole permanent magnet linear synchronous motor (PMLSM)being cited, by using Fourier transform method and "slot-by-slot", "pole -by-pole" current approach, a 3D e... In this paper, with the non-salient pole permanent magnet linear synchronous motor (PMLSM)being cited, by using Fourier transform method and "slot-by-slot", "pole -by-pole" current approach, a 3D electromagnetic field model of PMLSM is established. Special attention is paid to its structure and the influence of longitudinal and transverse end effect. The distribution of electromagnetic field of PMLSM can be obtained directly and promptly by using FFT algorithm. It can also be used for the analysis of other LSM. 展开更多
关键词 permanent magnet linear synchronous motor quasi-3D electromagnetic field model Fourier transform
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Insights into Three-Dimensional Radiofrequency Circuits Connections
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作者 Rabah Dahmani Olivier Valorge +5 位作者 Fengyuan Sun Samir Labiod Francis Calmon Saida Latreche Ian O'Connor Christian Gontrand 《Computer Technology and Application》 2011年第6期456-470,共15页
The authors state briefly the possibility of various simulators to handle propagation of electromagnetic waves along some interconnections, in 3D RF (Radio Frequency) circuits. The studies are first derived in the t... The authors state briefly the possibility of various simulators to handle propagation of electromagnetic waves along some interconnections, in 3D RF (Radio Frequency) circuits. The studies are first derived in the time domain: a Finite-Difference Time-Domain method is applied, taking spectra via FFTs (Fast Fourier Transform) as post-processors. Electric and magnetic field distributions, pulse propagations along stripline structures or vias are highlighted. The scattering parameters for various cases are extracted and compared. Some original issue of this work is an insight on crosstalk or shielding phenomena between lines. 展开更多
关键词 Maxwell's equations radio frequency (RF) numerical methods shielding effects through silicon via.
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