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Optimization of measurement distance of (109)~Cd K XRF system for obese subjects 被引量:1
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作者 HUANG Shi-Bin +3 位作者 mcneill F E 《Nuclear Science and Techniques》 SCIE CAS CSCD 2003年第1期86-88,共3页
The precision of results obtained from the ^109Cd K XRF in vivo measurement system of bone lead for obses subjects with high BMI( body mass index)was poor.The main factor affecting the precision was the distance betwe... The precision of results obtained from the ^109Cd K XRF in vivo measurement system of bone lead for obses subjects with high BMI( body mass index)was poor.The main factor affecting the precision was the distance between tibia and detector.Compared with the standard phantom,a large phantom was used to simulate the obese subject in the measurements at different distances to the detector.The counts of Compton scattering increased highly because of the tissue overlying and surrounding tibia of the obese subject.When the distance between leg and detector was too small,the instrument would produce the distorted X-ray spectra,so that the obtained data were inaccurate,In order to ensure good measuremtn precision and accuracy,the distance between leg and detector should be maintained at 25mm during the counting period.Meanwhile,the dead time displayed instantly on the instrument should be controlled to around 30%. 展开更多
关键词 X射线 荧光光谱 XRF 镉109 优化 人体 镉积累 测量
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构建光城域网的新技术
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作者 Mustafa A.G.Abushagur +2 位作者 Bill mcneill 赵锋 《通讯世界》 2001年第7期17-19,共3页
光联网领域的革新已经显著降低了带宽的供应成本.长途运营商是光通信研究成果商业化的第一个受益者.但在城域网中,光纤覆盖范围仅为数十或最多数百公里,而不像在长途网中那样为数千公里.城域网中波长分路的数量也要远大于长途网.在每一... 光联网领域的革新已经显著降低了带宽的供应成本.长途运营商是光通信研究成果商业化的第一个受益者.但在城域网中,光纤覆盖范围仅为数十或最多数百公里,而不像在长途网中那样为数千公里.城域网中波长分路的数量也要远大于长途网.在每一个节点上的每一个分路对带宽的要求也不尽相同.这些要求上的差别使城域网与长途网有所区别. 展开更多
关键词 光城域网 复用技术 光纤通信
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