排序方式: 共有14条查询结果,搜索用时 15 毫秒
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提出一种采用Kohonen网络算法进行12电极电容CT系统的图像重建的方法.该网络由输入和输出两层神经元组成,输入为12电极电容CT系统测量所得的66个电容值,输出对应管道介质的空间分布模式.该网络采用竞争算法无监督学习,实验结果证明,该网络有较强的抗噪声能力,可重建出较精确的介质分布图像 相似文献
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介绍了12电极ECT成像系统测量的原理及设计.研制了一种高频抗杂散电容的充电转换差分放大探测电路,并设计出与12电极相配合、数据稳定、高分辨的一套控制时序,较好的实现了低漂移、高灵敏度及低噪声的测量.该测量电路可应用于最大成像率为100帧/s的系统 相似文献
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The gas/solid flow regime of dense-phase pneumatic conveying of pulverized coal under a pressure of 4.0 MPa in horizontal pipeline 10 mm in diameter, is monitored by electrical capacitance tomography (ECT) using 8 electrodes. To improve the accuracy of the capacitance measurement, an AC-based single-channel capacitance measuring circuit was developed, and a modified iterative Landweber algorithm was used to reconstruct the image. A two-fluid model based on the kinetic theory of granular flow was used to study the three-dimensional steady-state flow behavior of dense-phase pneumatic conveying of pulverized coal. 相似文献
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Single-photon emission computerized tomography and positron emission tomography are essential medical imaging tools, for which the sampling angle number and scan time should be carefully chosen to give a good compromise between image quality and radiopharmaceutical dose. In this study, the image quality of different acquisition protocols was evaluated via varied angle number and count number per angle with Monte Carlo simulation data. It was shown that, when similar imaging counts were used, the factor of acquisition counts was more important than that of the sampling number in emission computerized tomography. To further reduce the activity requirement and the scan duration, an iterative image reconstruction algorithm for limited-view and low-dose tomography based on compressed sensing theory has been developed. The total variation regulation was added to the reconstruction process to improve the signal to noise Ratio and reduce artifacts caused by the limited angle sampling. Maximization of the maximum likelihood of the estimated image and the measured data and minimization of the total variation of the image are alternatively implemented. By using this advanced algorithm, the reconstruction process is able to achieve image quality matching or exceed that of normal scans with only half of the injection radiopharmaceutical dose. 相似文献
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随着输电电压升高到超高压、特高压,传统的基于电磁感应机理的电流互感器技术已暴露出越来越多的内在的、难以克服的缺点。因此,用电子电流互感器取代传统的电流互感器已是大势所趋。特别是目前在电力系统大力推进智能电网技术的形势下,电力系统对全光纤电子电流互感器技术的需求日趋增长。此外,在高频电流及微弱电流测量方面全光纤电流传感技术也有重要应用。在简要介绍全光纤电流传感技术的概念、基本分类之后,阐述了目前全光纤电流互感器技术实用化过程中遇到的主要技术障碍,探讨了可能的解决办法,介绍了光纤Bragg光栅、量子点掺杂光纤及光纤纳米线/微米线等新兴技术在光纤电流传感器中的应用。 相似文献
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Single-photon emission computerized tomography and positron emission tomography are essential med- ical imaging tools, for which the sampling angle number and scan time should be carefully chosen to give a good compromise between image quality and radiopharmaceutical dose. In this study, the image quality of different ac- quisition protocols was evaluated via varied angle number and count number per angle with Monte Carlo simulation data. It was shown that, when similar imaging counts were used, the factor of acquisition counts was more important than that of the sampling number in emission computerized tomography. To further reduce the activity requirement and the scan duration, an iterative image reconstruction algorithm for limited-view and low-dose tomography based on compressed sensing theory has been developed. The total variation regulation was added to the reconstruction process to improve the signal to noise Ratio and reduce artifacts caused by the limited angle sampling. Maximization of the maximum likelihood of the estimated image and the measured data and minimization of the total variation of the image are alternatively implemented. By using this advanced algorithm, the reconstruction process is able to achieve image quality matching or exceed that of normal scans with only half of the injection radiopharmaceutical dose. 相似文献