In this paper,the study of projection properties of two-level factorials in view of geometry is reported.The concept of uniformity pattern is defined.Based on this new concept,criteria of uniformity resolution and min...In this paper,the study of projection properties of two-level factorials in view of geometry is reported.The concept of uniformity pattern is defined.Based on this new concept,criteria of uniformity resolution and minimum projection uniformity are proposed for comparing two-level factorials.Relationship between minimum projection uniformity and other criteria such as minimum aberration,generalized minimum aberration and orthogonality is made explict.This close relationship raises the hope of improving the connection between uniform design theory and factorial design theory.Our results provide a justification of orthogonality,minimum aberration,and generalized minimum aberration from a natural geometrical interpretation.展开更多
目的总结Hawkeye SPECT/CT固有均匀性在日常质量控制中的校准方法,并分析其产生性能漂移的常见原因。方法选择我院2013年1月-6月Hawkeye仪器日常质控的部分数据,分析仪器的均匀性等基本情况;针对我院Hawkeye探头出现的中心视野＂亮点＂...目的总结Hawkeye SPECT/CT固有均匀性在日常质量控制中的校准方法,并分析其产生性能漂移的常见原因。方法选择我院2013年1月-6月Hawkeye仪器日常质控的部分数据,分析仪器的均匀性等基本情况;针对我院Hawkeye探头出现的中心视野＂亮点＂,而且中心视野均匀性（Center Field of View,CFOV）均匀性值偏离很大（23.17%）的现象,使用仪器提供的迭代校准程序（Iterative Calibration,ITER）进行校正。结果仪器固有均匀性通过校正后均可达到正常值（CFOV〈3.5%）。结论 Hawkeye仪器均匀性值的漂移可以通过有效的日常质量控制得到校准,通过校准可以使相机均匀性保持在较理想状态、仪器整体性能得以保证。展开更多
The structure and working principle of Micromegas （MICRO Mesh Gaseous Structure） is discussed. Some radiation sources of α and X rays are used to test this detector. The optimized electric-field intensity of the co...The structure and working principle of Micromegas （MICRO Mesh Gaseous Structure） is discussed. Some radiation sources of α and X rays are used to test this detector. The optimized electric-field intensity of the conversion gap is obtained. The transmission of electrons and the uniformity of the amplification gap are also presented. The energy resolution of the 5.9 keV peak is better than 27%.展开更多
A Gas Electron Multiplier （GEM） detector with an effective area of 300 mm×300 mm has been constructed using a novel self-stretching technique, which allows a highly flexible and efficient GEM detector assembly ...A Gas Electron Multiplier （GEM） detector with an effective area of 300 mm×300 mm has been constructed using a novel self-stretching technique, which allows a highly flexible and efficient GEM detector assembly free of glue or spacers. This makes the re-opening and repair of the GEM detectors possible and significantly reduces the scrap rate in the mass production of large-area GEM detectors. With the technique, the assembly time can be limited to a few hours, a factor of ten improvement compared to that using gluing techniques. The details of design and assembly procedure of the 300 mm×300 mm GEM detector are described in this paper. This detector was tested with 8 keV X-rays for the effective gain, energy resolution and performance uniformity. The results show that the typical energy resolution is 20% at an effective gain of about 10-4, with fairly good uniformity.展开更多
The Shanghai Synchrotron Radiation Facility （SSRF）booster ring, a full energy injector for the storage ring, is deigned to accelerate the electron beam energy from 150 MeV to 3.5 GeV that demands high extraction eff...The Shanghai Synchrotron Radiation Facility （SSRF）booster ring, a full energy injector for the storage ring, is deigned to accelerate the electron beam energy from 150 MeV to 3.5 GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping. Closed orbit distortion （COD） caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting. Considering the affections of random errors in measurement, both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5 is given as the final installation sequence of the booster bending magnets in this paper.展开更多
目的校正锥形束CT投影中的散射信号,以提高图像质量。方法使用条状挡板测量Varian机载kV级锥形束CT投影图像中的散射信号,并将其从再次扫描的投影中扣除,以获得原始射线的投影图像。使用空域自适应的BayesShrink小波对投影图像进行去噪...目的校正锥形束CT投影中的散射信号,以提高图像质量。方法使用条状挡板测量Varian机载kV级锥形束CT投影图像中的散射信号,并将其从再次扫描的投影中扣除,以获得原始射线的投影图像。使用空域自适应的BayesShrink小波对投影图像进行去噪处理,并导入Varian On Board Imager工作站进行重建;比较处理前后的图像质量。结果校正后图像的低对比度分辨力提高,噪声降低,CT值的准确性和均匀性得到改善。结论条状挡板能准确获取投影图像中的散射信号;扣除散射信号后使用小波阈值法去噪,可有效提高图像质量。展开更多
基金partially supported by the Hong Kong RGC grant,RGC/HKBU 2044/02Pthe National Natural Science Foundation of China(Grant No.10071029)+1 种基金the Project-sponsored by SRF for ROCS(SEM)the NSF of Hubei Province for the second author.
文摘In this paper,the study of projection properties of two-level factorials in view of geometry is reported.The concept of uniformity pattern is defined.Based on this new concept,criteria of uniformity resolution and minimum projection uniformity are proposed for comparing two-level factorials.Relationship between minimum projection uniformity and other criteria such as minimum aberration,generalized minimum aberration and orthogonality is made explict.This close relationship raises the hope of improving the connection between uniform design theory and factorial design theory.Our results provide a justification of orthogonality,minimum aberration,and generalized minimum aberration from a natural geometrical interpretation.
文摘目的总结Hawkeye SPECT/CT固有均匀性在日常质量控制中的校准方法,并分析其产生性能漂移的常见原因。方法选择我院2013年1月-6月Hawkeye仪器日常质控的部分数据,分析仪器的均匀性等基本情况;针对我院Hawkeye探头出现的中心视野＂亮点＂,而且中心视野均匀性（Center Field of View,CFOV）均匀性值偏离很大（23.17%）的现象,使用仪器提供的迭代校准程序（Iterative Calibration,ITER）进行校正。结果仪器固有均匀性通过校正后均可达到正常值（CFOV〈3.5%）。结论 Hawkeye仪器均匀性值的漂移可以通过有效的日常质量控制得到校准,通过校准可以使相机均匀性保持在较理想状态、仪器整体性能得以保证。
基金Supported by National Natural Science Foundation of China (10775132)
文摘The structure and working principle of Micromegas （MICRO Mesh Gaseous Structure） is discussed. Some radiation sources of α and X rays are used to test this detector. The optimized electric-field intensity of the conversion gap is obtained. The transmission of electrons and the uniformity of the amplification gap are also presented. The energy resolution of the 5.9 keV peak is better than 27%.
基金Supported by National Natural Science Foundation of China(11205151,11375180)
文摘A Gas Electron Multiplier （GEM） detector with an effective area of 300 mm×300 mm has been constructed using a novel self-stretching technique, which allows a highly flexible and efficient GEM detector assembly free of glue or spacers. This makes the re-opening and repair of the GEM detectors possible and significantly reduces the scrap rate in the mass production of large-area GEM detectors. With the technique, the assembly time can be limited to a few hours, a factor of ten improvement compared to that using gluing techniques. The details of design and assembly procedure of the 300 mm×300 mm GEM detector are described in this paper. This detector was tested with 8 keV X-rays for the effective gain, energy resolution and performance uniformity. The results show that the typical energy resolution is 20% at an effective gain of about 10-4, with fairly good uniformity.
文摘The Shanghai Synchrotron Radiation Facility （SSRF）booster ring, a full energy injector for the storage ring, is deigned to accelerate the electron beam energy from 150 MeV to 3.5 GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping. Closed orbit distortion （COD） caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting. Considering the affections of random errors in measurement, both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5 is given as the final installation sequence of the booster bending magnets in this paper.
文摘目的校正锥形束CT投影中的散射信号,以提高图像质量。方法使用条状挡板测量Varian机载kV级锥形束CT投影图像中的散射信号,并将其从再次扫描的投影中扣除,以获得原始射线的投影图像。使用空域自适应的BayesShrink小波对投影图像进行去噪处理,并导入Varian On Board Imager工作站进行重建;比较处理前后的图像质量。结果校正后图像的低对比度分辨力提高,噪声降低,CT值的准确性和均匀性得到改善。结论条状挡板能准确获取投影图像中的散射信号;扣除散射信号后使用小波阈值法去噪,可有效提高图像质量。
