X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of sample...X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus beating tremendous potential for future clinical diagnosis. In this work, by changing the accel- erating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot-Lau interferometer （located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan） versus tube voltage. Ex- perimental results and data analysis show that within a range this x-ray Talbot-Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ~ 44%. This x-ray Talbot-Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum.展开更多
选取《通信铁塔标准图集》中0.65 k N/m2风压下高度50 m的四平台三管塔,建立其有限元分析模型,采用动力AP法对模型进行倒塌安全性分析。分析表明:对于风压0.65 k N/m2下50 m三管塔,其塔段3(38 m)以上部分塔身安全储备较大,当塔柱失效后...选取《通信铁塔标准图集》中0.65 k N/m2风压下高度50 m的四平台三管塔,建立其有限元分析模型,采用动力AP法对模型进行倒塌安全性分析。分析表明:对于风压0.65 k N/m2下50 m三管塔,其塔段3(38 m)以上部分塔身安全储备较大,当塔柱失效后塔架不会发生倒塌;塔身挡风面与风向呈一定角度时,塔顶水平位移要小于风向垂直于挡风面的工况;当失效塔柱承受拉力时,重力荷载将起到有利的作用;在进行塔身设计时,应尽量避免塔身迎风面与主风向垂直,并降低塔柱承受的压应力水平。展开更多
选取《通信铁塔标准图集》中0.65 k N/m2风压下高度50 m的四平台角钢塔,采用ABAQUS建立FE分析模型,并对其模型进行动力AP分析,研究在风荷载作用下标准角钢塔的倒塌安全性。分析表明:对于风压0.65 k N/m2下50 m标准角钢塔,在任意风向下...选取《通信铁塔标准图集》中0.65 k N/m2风压下高度50 m的四平台角钢塔,采用ABAQUS建立FE分析模型,并对其模型进行动力AP分析,研究在风荷载作用下标准角钢塔的倒塌安全性。分析表明:对于风压0.65 k N/m2下50 m标准角钢塔,在任意风向下的单一塔柱失效,均不会引发塔架的整体倒塌。当失效塔柱承受拉力时,重力荷载将起到有利的作用,因此在进行塔身设计时,应降低塔柱承受的压应力水平,尽量使塔身迎风面与主风向垂直。展开更多
Dual-energy X-ray absorptiometry（DEXA） has been widely applied to measure the bone mineral density（BMD） and soft-tissue composition of the human body. However, the use of DEXA is greatly limited for lowZ materials...Dual-energy X-ray absorptiometry（DEXA） has been widely applied to measure the bone mineral density（BMD） and soft-tissue composition of the human body. However, the use of DEXA is greatly limited for lowZ materials such as soft tissues due to their weak absorption, while X-ray phase-contrast imaging（XPCI） shows significantly improved contrast in comparison with the conventional standard absorption-based X-ray imaging for soft tissues. In this paper, we propose a novel X-ray phase-contrast method to measure the area density of low-Z materials, including a single-energy method and a dual-energy method. The single-energy method is for the area density calculation of one low-Z material, while the dual-energy method aims to calculate the area densities of two low-Z materials simultaneously. Comparing the experimental and simulation results with the theoretical ones, the new method proves to have the potential to replace DEXA in area density measurement. The new method sets the prerequisites for a future precise and low-dose area density calculation method for low-Z materials.展开更多
基金Project supported by the Major State Basic Research Development Program of China(Grant No.2012CB825800)the Science Fund for Creative Research Groups,China(Grant No.11321503)+1 种基金the National Natural Science Foundation of China(Grant Nos.11179004,10979055,11205189,and 11205157)the Japan–Asia Youth Exchange Program in Science(SAKURA Exchange Program in Science)Administered by the Japan Science and Technology Agency
文摘X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus beating tremendous potential for future clinical diagnosis. In this work, by changing the accel- erating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot-Lau interferometer （located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan） versus tube voltage. Ex- perimental results and data analysis show that within a range this x-ray Talbot-Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ~ 44%. This x-ray Talbot-Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum.
文摘选取《通信铁塔标准图集》中0.65 k N/m2风压下高度50 m的四平台三管塔,建立其有限元分析模型,采用动力AP法对模型进行倒塌安全性分析。分析表明:对于风压0.65 k N/m2下50 m三管塔,其塔段3(38 m)以上部分塔身安全储备较大,当塔柱失效后塔架不会发生倒塌;塔身挡风面与风向呈一定角度时,塔顶水平位移要小于风向垂直于挡风面的工况;当失效塔柱承受拉力时,重力荷载将起到有利的作用;在进行塔身设计时,应尽量避免塔身迎风面与主风向垂直,并降低塔柱承受的压应力水平。
文摘选取《通信铁塔标准图集》中0.65 k N/m2风压下高度50 m的四平台角钢塔,采用ABAQUS建立FE分析模型,并对其模型进行动力AP分析,研究在风荷载作用下标准角钢塔的倒塌安全性。分析表明:对于风压0.65 k N/m2下50 m标准角钢塔,在任意风向下的单一塔柱失效,均不会引发塔架的整体倒塌。当失效塔柱承受拉力时,重力荷载将起到有利的作用,因此在进行塔身设计时,应降低塔柱承受的压应力水平,尽量使塔身迎风面与主风向垂直。
基金Supported by the Major State Basic Research Development Program(2012CB825800)the Science Fund for Creative Research Groups(11321503)+2 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences(KJCX2-YWN42)the National Natural Science Foundation of China(11179004,10979055,11205189,and 11205157)the Fundamental Research Funds for the Central Universities(WK2310000021)
基金Supported by Major State Basic Research Development Program(2012CB825800)Science Fund for Creative Research Groups(11321503)National Natural Science Foundation of China(11179004,10979055,11205189,11205157)
文摘Dual-energy X-ray absorptiometry（DEXA） has been widely applied to measure the bone mineral density（BMD） and soft-tissue composition of the human body. However, the use of DEXA is greatly limited for lowZ materials such as soft tissues due to their weak absorption, while X-ray phase-contrast imaging（XPCI） shows significantly improved contrast in comparison with the conventional standard absorption-based X-ray imaging for soft tissues. In this paper, we propose a novel X-ray phase-contrast method to measure the area density of low-Z materials, including a single-energy method and a dual-energy method. The single-energy method is for the area density calculation of one low-Z material, while the dual-energy method aims to calculate the area densities of two low-Z materials simultaneously. Comparing the experimental and simulation results with the theoretical ones, the new method proves to have the potential to replace DEXA in area density measurement. The new method sets the prerequisites for a future precise and low-dose area density calculation method for low-Z materials.
