期刊文献+
共找到2篇文章
< 1 >
每页显示 20 50 100
基于超声散射回波功率谱的热疗无损测温模型 被引量:6
1
作者 牛金海 周世平 王鸿樟 《声学学报》 EI CSCD 北大核心 2002年第2期185-190,共6页
在随机起伏介质超声散射理论下,基于组织超声散射问波功率谱,提出一种无损获取组织温度信息的新方法。组织中声速及密度的随机起伏引起超声散射,散射回波声压谱的均方值与组织中声速c、声速对温度的梯度dc/dt和组织的平均温度... 在随机起伏介质超声散射理论下,基于组织超声散射问波功率谱,提出一种无损获取组织温度信息的新方法。组织中声速及密度的随机起伏引起超声散射,散射回波声压谱的均方值与组织中声速c、声速对温度的梯度dc/dt和组织的平均温度T等有关。分析组织散射超声回波信号平均归一化功率谱与组织温度的关系,可以从超声散射回波中有效提取组织温度信息。理论分析和模拟实验为医学上肿瘤热疗提供了一种新的无损测温的方法和思路。 展开更多
关键词 肿瘤 热疗 无损测量模型 超声散射回波功率谱
下载PDF
Path loss modelling and comparison based on the radio propagation measurement at 3.5GHz 被引量:4
2
作者 王萍 Li Yingzhe +2 位作者 Chang Ruoting Sun Kun Xu Hui 《High Technology Letters》 EI CAS 2009年第3期272-276,共5页
Wideband IMT-Advanced mobile communication systems tend to operate in the high frequency bands due to a relatively large capacity available. Thus, Measurement and modelling methods of radio propaga- tion eharaeteristi... Wideband IMT-Advanced mobile communication systems tend to operate in the high frequency bands due to a relatively large capacity available. Thus, Measurement and modelling methods of radio propaga- tion eharaeteristics are proposed for the field test of Chinese 4th generation (4G) trial system. The mea- surement system is established for 3.5GHz based on the sophistieated measurement instruments and the virtual instrument teehnology. The characteristic parameters of radio propagation sueh as path loss (PL) exponent and shadow fading standard deviation are extracted from measurement data, which result in the path loss model finally. The comparisons with other existing international models results validate our mea- surement in terms of path loss model. Based on the analysis of the existing extension model assumed for the microwave frequency at 3.5GHz, we find that the Stanford University Interim (SUI) model fits very well with the measurement result in the hotspot scenario, while the COST 231 model is closer to the mea- surement result in the suburban scenario. This result provides a measurement-based channel referenee for the development of the future IMT-Advanced systems in China. 展开更多
关键词 IMT-advaneed channel measurement channel model path loss radio propagation Stanford University Interim (SUI) COST 231 Hata WINNER
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部