汽车尾气的主要成分是CO气体,是公路隧道通风设计的一项重要参数。准确、快速地预测隧道内CO气体浓度,能够为隧道通风控制提供有力参考,有助于CO气体浓度的及时控制,对保障隧道内人员的健康、安全和隧道绿色节能十分必要。采用公路隧道...汽车尾气的主要成分是CO气体,是公路隧道通风设计的一项重要参数。准确、快速地预测隧道内CO气体浓度,能够为隧道通风控制提供有力参考,有助于CO气体浓度的及时控制,对保障隧道内人员的健康、安全和隧道绿色节能十分必要。采用公路隧道实地监测CO气体浓度数据,建立了以监测点位置、交通量、车速、风速为输入特征的公路隧道CO气体浓度预测随机森林模型。通过整理3300 m长隧道CO气体浓度数据,对比了CO气体浓度实测数据与模型预测值,验证了模型的预测精度。结果表明,基于随机森林建立的CO气体浓度预测模型具有良好的预测精度,能够准确地预测隧道内CO气体浓度,测试集的均方根误差(root mean square error,RMSE)和决定系数R^(2)分别为0.4974和0.9437;该预测模型性能显著优于线性回归模型和支持向量机模型;预测模型能够推广应用于其他隧道的CO气体浓度预测,对应的RMSE和R^(2)分别为0.9095和0.7295,可以在已知测点位置、交通量、车速、风速的情况下预判隧道内CO气体浓度,为隧道通风控制或安全预警提供数据参考;特征重要性分析结果显示,测点位置对隧道内CO浓度的影响最大,在隧道出口处CO气体浓度值最高;随着风速的增大,隧道内CO气体浓度逐渐减小。展开更多
Background There is no consensus regarding the performance for endorectal ultrasonography （ERUS） at every stage of rectal cancer. Thus, the purpose of our study was to further assess the value of ERUS in the preoper...Background There is no consensus regarding the performance for endorectal ultrasonography （ERUS） at every stage of rectal cancer. Thus, the purpose of our study was to further assess the value of ERUS in the preoperative staging of rectal cancer. Methods A retrospective study was performed with 44 consecutive patients （mean age： （63.3±10.2） years） who underwent surgical treatment for endorectal carcinoma and were preoperatively evaluated using Biplane ERUS between September 2008 and December 2010. We compared the ERUS staging with the pathological findings based on surgical specimens. Results ERUS staging agreed with the histologic staging in 39 of the 44 （88.6%） patients： the agreement on the depth of transmural invasion was good （k= 0.73; 95% CI： 0.60-0.86, P =0.000）. The detection sensitivities of rectal cancer with ERUS were as follows： T1 85.7%, T2 87.5%, T3 88.9%, and T4 100.0% with specificity values of T1 97.3%, T2 92.9%, T3 96.2%, and T4 97.6%. ERUS correctly staged patients with T1 95.5%, T2 90.9%, T3 70.5 %, and T4 97.7%. The positive predictive value of ERUS was lowest for T4 （75%）, but highest for T3 （94.1%） followed by T2 （87.5%） and T1 （85.7%）; the negative predictive values of ERUS from high to low were ordered as T4 （100%）, T1 （97.3%）, T2 （92.9%）, and T3 （92.6%）. The percentage of total over-staged cases was 4.5% and the under-staged cases was 6.8%. The extent of perirectal lymph node metastases was determined with a sensitivity of 68.4% （13/19）, specificity of 80.0% （20/25）, and diagnostic accuracy of 75.0% （33/44）.展开更多
文摘汽车尾气的主要成分是CO气体,是公路隧道通风设计的一项重要参数。准确、快速地预测隧道内CO气体浓度,能够为隧道通风控制提供有力参考,有助于CO气体浓度的及时控制,对保障隧道内人员的健康、安全和隧道绿色节能十分必要。采用公路隧道实地监测CO气体浓度数据,建立了以监测点位置、交通量、车速、风速为输入特征的公路隧道CO气体浓度预测随机森林模型。通过整理3300 m长隧道CO气体浓度数据,对比了CO气体浓度实测数据与模型预测值,验证了模型的预测精度。结果表明,基于随机森林建立的CO气体浓度预测模型具有良好的预测精度,能够准确地预测隧道内CO气体浓度,测试集的均方根误差(root mean square error,RMSE)和决定系数R^(2)分别为0.4974和0.9437;该预测模型性能显著优于线性回归模型和支持向量机模型;预测模型能够推广应用于其他隧道的CO气体浓度预测,对应的RMSE和R^(2)分别为0.9095和0.7295,可以在已知测点位置、交通量、车速、风速的情况下预判隧道内CO气体浓度,为隧道通风控制或安全预警提供数据参考;特征重要性分析结果显示,测点位置对隧道内CO浓度的影响最大,在隧道出口处CO气体浓度值最高;随着风速的增大,隧道内CO气体浓度逐渐减小。
文摘Background There is no consensus regarding the performance for endorectal ultrasonography （ERUS） at every stage of rectal cancer. Thus, the purpose of our study was to further assess the value of ERUS in the preoperative staging of rectal cancer. Methods A retrospective study was performed with 44 consecutive patients （mean age： （63.3±10.2） years） who underwent surgical treatment for endorectal carcinoma and were preoperatively evaluated using Biplane ERUS between September 2008 and December 2010. We compared the ERUS staging with the pathological findings based on surgical specimens. Results ERUS staging agreed with the histologic staging in 39 of the 44 （88.6%） patients： the agreement on the depth of transmural invasion was good （k= 0.73; 95% CI： 0.60-0.86, P =0.000）. The detection sensitivities of rectal cancer with ERUS were as follows： T1 85.7%, T2 87.5%, T3 88.9%, and T4 100.0% with specificity values of T1 97.3%, T2 92.9%, T3 96.2%, and T4 97.6%. ERUS correctly staged patients with T1 95.5%, T2 90.9%, T3 70.5 %, and T4 97.7%. The positive predictive value of ERUS was lowest for T4 （75%）, but highest for T3 （94.1%） followed by T2 （87.5%） and T1 （85.7%）; the negative predictive values of ERUS from high to low were ordered as T4 （100%）, T1 （97.3%）, T2 （92.9%）, and T3 （92.6%）. The percentage of total over-staged cases was 4.5% and the under-staged cases was 6.8%. The extent of perirectal lymph node metastases was determined with a sensitivity of 68.4% （13/19）, specificity of 80.0% （20/25）, and diagnostic accuracy of 75.0% （33/44）.
