A physical model has been constructed to represent the condensate film pattern on a horizontal downward- facing surface with fins,which is based on visual observation in experiment.The results of analysis using this m...A physical model has been constructed to represent the condensate film pattern on a horizontal downward- facing surface with fins,which is based on visual observation in experiment.The results of analysis using this model confirms the validity of the critical wave length formula obtained from Rayleigh-Taylor stability analysis. This formula may be used as a criterion to design horizontal downward-facing surfaces with fins that can best destabilize the condensate film,thus enhancing condensation heat transfer.展开更多
An experimental investigation of irregular wave forces on quasi-ellipse caisson structures is presented. Irregular waves were generated based on the Jonswap spectrum with two significant wave heights, and the spectrum...An experimental investigation of irregular wave forces on quasi-ellipse caisson structures is presented. Irregular waves were generated based on the Jonswap spectrum with two significant wave heights, and the spectrum peak periods range from 1.19 s to 1.81 s. Incident wave directions relative to the centre line of the multiple caissons are from 0＆#176; to 22.5＆#176;. The spacing between caissons ranges from 2 to 3 times that of the width of the caisson. The effects of these parameters on the wave forces of both the perforated and non-perforated caissons were compared and analyzed. It was found that the perforated caisson can reduce wave forces, especially in the transverse direction. Furthermore, the relative interval and incident wave direction have significant effects on the wave forces in the case of multiple caissons.展开更多
目的本研究旨在评估宫颈机能不全(cervical insufficiency,CI)与自发性早产(spontaneous preterm birth,SPB)之间的关联,并探讨宫颈剪切波弹性成像(shear wave elasticity,SWE)、宫颈长度(cervical length,CL)和宫颈前角(anterior cervi...目的本研究旨在评估宫颈机能不全(cervical insufficiency,CI)与自发性早产(spontaneous preterm birth,SPB)之间的关联,并探讨宫颈剪切波弹性成像(shear wave elasticity,SWE)、宫颈长度(cervical length,CL)和宫颈前角(anterior cervical angle,ACA)在预测CI引起的SPB中的应用价值。方法本研究纳入了2023年6月至2024年1月期间在南通大学附属医院及江南大学附属妇产医院产前门诊就诊或住院治疗的786例孕妇,其中足月组723例孕妇,早产组63例孕妇。使用迈瑞Resona R9 Pro/Eagus R9s超声仪,配备剪切波弹性成像软件,进行宫颈SWEI、CL和ACA的测量。此外,按照受检孕周将孕妇分为19~23^(+6)周、24~27^(+6)周、28~33^(+6)周、34~36^(+6)周4组,评估孕周与超声参数的关系。结果早产组孕妇的CL平均为25.42 mm,显著低于足月组的29.71 mm(P<0.001)。ACA在早产组平均为121°,高于足月组的99°(P<0.001)。宫颈各部位的SWE值在早产组也显著低于足月组:外口前唇(AE)为6.47 k Pa对比9.91 k Pa(P<0.001)、内口前唇(AI)为10.98 k Pa对比18.62 k Pa(P<0.001)、内口后唇(PI)为11.32 k Pa对比21.09 k Pa(P<0.001)、外口后唇(PE)为8.16 k Pa对比13.24 k Pa(P<0.001)。CL与孕周存在显著的负相关(r=-0.278,P=0.001)。联合预测指标在预测早产方面显示出较高的准确性和特异性,曲线下面积(AUC)达到0.952,灵敏度和特异度分别为95%和86%。结论宫颈SWE、CL和ACA的联合使用可以显著提高对CI导致SPB的预测效能,可以为临床医生提供了一个更全面、准确的工具,以识别高危孕妇并及时采取干预措施,减少早产的发生,改善母婴预后。展开更多
The new distributions of the statistics of wave groups based on the maximum entropy principle are presented. The maximum entropy distributions appear to be superior to conventional distributions when applied to a limi...The new distributions of the statistics of wave groups based on the maximum entropy principle are presented. The maximum entropy distributions appear to be superior to conventional distributions when applied to a limited amount of information. Its applications to the wave group properties show the effectiveness of the maximum entropy distribution. FFF filtering method is employed to obtain the wave envelope fast and efficiently. Comparisons of both the maximum entropy distribution and the distribution of Longuet-Higgins （1984） with the laboratory wind-wave data show that the former gives a better fit.展开更多
文摘A physical model has been constructed to represent the condensate film pattern on a horizontal downward- facing surface with fins,which is based on visual observation in experiment.The results of analysis using this model confirms the validity of the critical wave length formula obtained from Rayleigh-Taylor stability analysis. This formula may be used as a criterion to design horizontal downward-facing surfaces with fins that can best destabilize the condensate film,thus enhancing condensation heat transfer.
基金Foundation item： Supported by the National Natural Science Foundation of China under Grant No. 51109032, and the National Natural Science Foundation of China under Grant No. 50921001.
文摘An experimental investigation of irregular wave forces on quasi-ellipse caisson structures is presented. Irregular waves were generated based on the Jonswap spectrum with two significant wave heights, and the spectrum peak periods range from 1.19 s to 1.81 s. Incident wave directions relative to the centre line of the multiple caissons are from 0＆#176; to 22.5＆#176;. The spacing between caissons ranges from 2 to 3 times that of the width of the caisson. The effects of these parameters on the wave forces of both the perforated and non-perforated caissons were compared and analyzed. It was found that the perforated caisson can reduce wave forces, especially in the transverse direction. Furthermore, the relative interval and incident wave direction have significant effects on the wave forces in the case of multiple caissons.
文摘目的本研究旨在评估宫颈机能不全(cervical insufficiency,CI)与自发性早产(spontaneous preterm birth,SPB)之间的关联,并探讨宫颈剪切波弹性成像(shear wave elasticity,SWE)、宫颈长度(cervical length,CL)和宫颈前角(anterior cervical angle,ACA)在预测CI引起的SPB中的应用价值。方法本研究纳入了2023年6月至2024年1月期间在南通大学附属医院及江南大学附属妇产医院产前门诊就诊或住院治疗的786例孕妇,其中足月组723例孕妇,早产组63例孕妇。使用迈瑞Resona R9 Pro/Eagus R9s超声仪,配备剪切波弹性成像软件,进行宫颈SWEI、CL和ACA的测量。此外,按照受检孕周将孕妇分为19~23^(+6)周、24~27^(+6)周、28~33^(+6)周、34~36^(+6)周4组,评估孕周与超声参数的关系。结果早产组孕妇的CL平均为25.42 mm,显著低于足月组的29.71 mm(P<0.001)。ACA在早产组平均为121°,高于足月组的99°(P<0.001)。宫颈各部位的SWE值在早产组也显著低于足月组:外口前唇(AE)为6.47 k Pa对比9.91 k Pa(P<0.001)、内口前唇(AI)为10.98 k Pa对比18.62 k Pa(P<0.001)、内口后唇(PI)为11.32 k Pa对比21.09 k Pa(P<0.001)、外口后唇(PE)为8.16 k Pa对比13.24 k Pa(P<0.001)。CL与孕周存在显著的负相关(r=-0.278,P=0.001)。联合预测指标在预测早产方面显示出较高的准确性和特异性,曲线下面积(AUC)达到0.952,灵敏度和特异度分别为95%和86%。结论宫颈SWE、CL和ACA的联合使用可以显著提高对CI导致SPB的预测效能,可以为临床医生提供了一个更全面、准确的工具,以识别高危孕妇并及时采取干预措施,减少早产的发生,改善母婴预后。
基金This work was financially supported by the National Natural Science Foundation of China (Grant No50479028)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No20060423009)
文摘The new distributions of the statistics of wave groups based on the maximum entropy principle are presented. The maximum entropy distributions appear to be superior to conventional distributions when applied to a limited amount of information. Its applications to the wave group properties show the effectiveness of the maximum entropy distribution. FFF filtering method is employed to obtain the wave envelope fast and efficiently. Comparisons of both the maximum entropy distribution and the distribution of Longuet-Higgins （1984） with the laboratory wind-wave data show that the former gives a better fit.
