在Bounding-box及其改进方法研究中,普遍采用正方形的重叠区域的质心作为定位的结果,然而该正方形与实际无线传感器节点的通信区域模型之间存在较大差异,导致定位误差较大。针对此问题,提出一种改进的Bounding-box定位方法。该方法在定...在Bounding-box及其改进方法研究中,普遍采用正方形的重叠区域的质心作为定位的结果,然而该正方形与实际无线传感器节点的通信区域模型之间存在较大差异,导致定位误差较大。针对此问题,提出一种改进的Bounding-box定位方法。该方法在定位时,不再采用正方形的通信区域模型,而是采用圆形的通信区域模型进行定位。基于仿真数据以及采用3种典型通信环境下真实的到达信号强度指示(received signal strength indicator,RSSI)数据完成定位实验,实验结果表明,该方法具有较高的定位精度,因此具有一定的实际应用价值。展开更多
Objective To explore the contrast-enhanced ultrasonographic features for quantitative assessment of hepatic fibrosis. Methods 86 patients with chronic viral hepatitis B were enrolled in this study from March 2007 to A...Objective To explore the contrast-enhanced ultrasonographic features for quantitative assessment of hepatic fibrosis. Methods 86 patients with chronic viral hepatitis B were enrolled in this study from March 2007 to August 2009. The patients were classified into 5 groups (S0-S4) according to fibrosis stage evaluated with ultrasound guided liver biopsy. New contrast-enhanced ultrasonography (CEUS) features including area under the time-intensity curve (TIC) of portal venous phase/hepatic arterial phase (Qp/Qa) and intensity of portal venous phase/hepatic arterial phase (Ip/Ia) were used to detect the blood supply ratio (portal vein/hepatic artery) in each group. Arrival time of portal vein trunk (Tp) and decreasing rate of TIC (β ) were also analyzed. Results Qp/Qa and Ip/Ia decreased from S0 to S4, while Tp and β increased. These 4 features were significantly correlated with the degree of fibrosis (P<0.001) and were significantly different among the five groups (P<0.001). Sensitivity and specificity of Ip/Ia were 80% and 86% for groups ≥S1, 75% and 86% for groups ≥ S2, 71% and 84% for groups ≥ S3, and 76% and 80% for group S4, respectively. Sensitivity and specificity of Qp/Qa were 70% and 88% for groups ≥ S1, 80% and 76% for groups ≥ S2, 74% and 70% for groups ≥ S3, and 81% and 95% for group S4, respectively. Conclusion Ip/Ia and Qp/Qa could be adopted as reliable, non-invasive features for quantitative assessment of hepatic fibrosis.展开更多
文摘在Bounding-box及其改进方法研究中,普遍采用正方形的重叠区域的质心作为定位的结果,然而该正方形与实际无线传感器节点的通信区域模型之间存在较大差异,导致定位误差较大。针对此问题,提出一种改进的Bounding-box定位方法。该方法在定位时,不再采用正方形的通信区域模型,而是采用圆形的通信区域模型进行定位。基于仿真数据以及采用3种典型通信环境下真实的到达信号强度指示(received signal strength indicator,RSSI)数据完成定位实验,实验结果表明,该方法具有较高的定位精度,因此具有一定的实际应用价值。
基金Supported by PhD Programs Foundation of Ministry of Education of China (No. 20090001110092)
文摘Objective To explore the contrast-enhanced ultrasonographic features for quantitative assessment of hepatic fibrosis. Methods 86 patients with chronic viral hepatitis B were enrolled in this study from March 2007 to August 2009. The patients were classified into 5 groups (S0-S4) according to fibrosis stage evaluated with ultrasound guided liver biopsy. New contrast-enhanced ultrasonography (CEUS) features including area under the time-intensity curve (TIC) of portal venous phase/hepatic arterial phase (Qp/Qa) and intensity of portal venous phase/hepatic arterial phase (Ip/Ia) were used to detect the blood supply ratio (portal vein/hepatic artery) in each group. Arrival time of portal vein trunk (Tp) and decreasing rate of TIC (β ) were also analyzed. Results Qp/Qa and Ip/Ia decreased from S0 to S4, while Tp and β increased. These 4 features were significantly correlated with the degree of fibrosis (P<0.001) and were significantly different among the five groups (P<0.001). Sensitivity and specificity of Ip/Ia were 80% and 86% for groups ≥S1, 75% and 86% for groups ≥ S2, 71% and 84% for groups ≥ S3, and 76% and 80% for group S4, respectively. Sensitivity and specificity of Qp/Qa were 70% and 88% for groups ≥ S1, 80% and 76% for groups ≥ S2, 74% and 70% for groups ≥ S3, and 81% and 95% for group S4, respectively. Conclusion Ip/Ia and Qp/Qa could be adopted as reliable, non-invasive features for quantitative assessment of hepatic fibrosis.
