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电离层ct技术
相关语句
  computerized ionospheric tomography
     Discussion about methods for data preprocessing in computerized ionospheric tomography
     电离层CT技术数据预处理方法的讨论
短句来源
     In the computerized ionospheric tomography, if direct Fourier method is used to reconstruct the image of electron density, several pseudo projections are grouped from a lot of individual pieces of TEC data by mathematical methods based on characteristics of data acquisition system geometry.
     在电离层CT技术中,若要用直接Fourier方法等变换方法重建成像,必须先根据其数据采集结构特点,用一定的数学方法由大量单个TEC值组合出若干个伪投影。
短句来源
  “电离层ct技术”译为未确定词的双语例句
     The limitations caused by data acquisition system geometry in computerizedionospheric tomography (CIT) in general bring some problems such as incompletedata obtained, nonuniform samples in pseudo-projections, incomplete spectrum infrequency domain. If direct FOurier method is used for reconstruction, the nonuniform samples in pseudo-projections must be uniformed and unknown region in twodimensional frequency domain must be estimated. With reference of Fourier extrapolation technique, the wavelet extrapolation technique is presented in this paper.
     电离层CT技术由于数据采集系统结构的局限性,致使所得数据不完全,伪投影中采样不均匀,频域谱值不完全.若用直接Fourier方法重建,必须对伪投影采样施以均匀化和在二维频域内进行估值.本文参照已有的Fourier外推技术,提出小波外推技术.理论分析和重建结果都说明小波外推技术具有较多优越性.
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  相似匹配句对
     X-CT technology progression
     X-CT技术进展
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     Dam CT Technology
     大坝CT技术
短句来源
     Discussion about methods for data preprocessing in computerized ionospheric tomography
     电离层CT技术数据预处理方法的讨论
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     TECHNOLOGY
     技术
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     Technology;
     技术
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  computerized ionospheric tomography
Reconstruction algorithm of computerized ionospheric tomography
      
Applying the technique of computer tomography to ionosphere detection, Computerized Ionospheric Tomography (CIT) can produce the large scale distribution of electron density in a two dimentional longitudinal section of ionosphere.
      
Automatic data acquisition system and reconstruction algorithm for computerized ionospheric tomography
      
In this paper, an IRI model assisted GPS-based Computerized Ionospheric Tomography (CIT) technique is developed to inverse the ionospheric electron density (IED) distribution over China.
      


The limitations caused by data acquisition system geometry in computerizedionospheric tomography (CIT) in general bring some problems such as incompletedata obtained, nonuniform samples in pseudo-projections, incomplete spectrum infrequency domain. If direct FOurier method is used for reconstruction, the nonuniform samples in pseudo-projections must be uniformed and unknown region in twodimensional frequency domain must be estimated. With reference of Fourier extrapolation technique, the wavelet extrapolation...

The limitations caused by data acquisition system geometry in computerizedionospheric tomography (CIT) in general bring some problems such as incompletedata obtained, nonuniform samples in pseudo-projections, incomplete spectrum infrequency domain. If direct FOurier method is used for reconstruction, the nonuniform samples in pseudo-projections must be uniformed and unknown region in twodimensional frequency domain must be estimated. With reference of Fourier extrapolation technique, the wavelet extrapolation technique is presented in this paper.Theoretical analysis and simulation are also shown, they demonstrate inverse abilityand feasibility of the method. Both theoretical analysis and reconstruction resultsshow much superiority of the wavelet transform extrapolation technique.

电离层CT技术由于数据采集系统结构的局限性,致使所得数据不完全,伪投影中采样不均匀,频域谱值不完全.若用直接Fourier方法重建,必须对伪投影采样施以均匀化和在二维频域内进行估值.本文参照已有的Fourier外推技术,提出小波外推技术.理论分析和重建结果都说明小波外推技术具有较多优越性.

In the technique of computerized ionospheric tomography, incomplete data is received because of limits in its data acquisition system geometry.So the reconstruction belongs to incomplete data reconstruction(limited angle tomography)in this case.Samples in projections are nonuniform, and two dimensional spectra plane obtained from projections spectra by using Fourier central slice theorem is not known completely. If the transform method for reconstruction will be used to reconstruct image,unknown spectra must...

In the technique of computerized ionospheric tomography, incomplete data is received because of limits in its data acquisition system geometry.So the reconstruction belongs to incomplete data reconstruction(limited angle tomography)in this case.Samples in projections are nonuniform, and two dimensional spectra plane obtained from projections spectra by using Fourier central slice theorem is not known completely. If the transform method for reconstruction will be used to reconstruct image,unknown spectra must be estimated.In this paper,the wavelet extrapolation method for estimate is used.The choice of wavelet function is various, the familiar Mexico hat wavelet is used in extrapolation.Deduction and simulation are also given.

电离层CT技术中由于数据采集系统的几何结构存在局限性,致使探测所得数据不完全,导致其成为不完全数据重建问题(有限角度层析)。投影中的采样点不均匀,且由投影谱通过Fourier中心切片原理组合而得的二维谱平面不完全可知,若要用变换方法重建成象,需要对其进行估计。可以利用小波外推方法估值,但是小波函数的选择具有多样性,文中选用比较常用的Mexico 草帽小波进行外推。给出了必要的推导过程和数值模拟结果。

In the computerized ionospheric tomography, if direct Fourier method is used to reconstruct the image of electron density, several pseudo projections are grouped from a lot of individual pieces of TEC data by mathematical methods based on characteristics of data acquisition system geometry. But, because of configuration of recievers and curvature of the Earth’s surface, the sample spacing is varied based on the angle of projection, and samples are nonuniform in an individual projection. Samples must be uniformized,...

In the computerized ionospheric tomography, if direct Fourier method is used to reconstruct the image of electron density, several pseudo projections are grouped from a lot of individual pieces of TEC data by mathematical methods based on characteristics of data acquisition system geometry. But, because of configuration of recievers and curvature of the Earth’s surface, the sample spacing is varied based on the angle of projection, and samples are nonuniform in an individual projection. Samples must be uniformized, then the spectrum can be obtained. The method of obtaining pseudo projections is shown, both short time Fourier extrapolation technique and wavelet extrapolation technique are also given for samples uniformizing based on the existent Fourier extraplation technique. The purpose of this article is to solve how to obtain data for transform reconstruction method from original data.

电离层CT技术中,若要用直接Fourier方法等变换方法重建成像,必须先根据其数据采集结构特点,用一定的数学方法由大量单个TEC值组合出若干个伪投影。然而,由于布站方式和地球表面曲率的影响,各伪投影中的采样点间距随投影角度的不同而变化,且间距不均匀,必须将每个投影中的采样均匀化,然后才可求其Fourier谱。给出了产生伪投影的方法,并依据现有的Fourier外推技术,提出采样点均匀化的短时Fourier外推技术和小波外推技术。目的是解决如何由原始数据得到适用于变换重建方法的数据。

 
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