A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition.The effect of the trigger system on the dispersion image of surface waves is empir...A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition.The effect of the trigger system on the dispersion image of surface waves is empirically known to be negligible,however,theoretical explanation regarding the effect of the trigger system is insufficient.This study systematically examines the theory for surface wave dispersion analysis and proves that the effect of the trigger system on a dispersion image is negligible via a solid theoretical explanation.Subsequently,based on the new theoretical explanation,an alternative method that uses only the relative phase difference between sensors to extract dispersion characteristics with better conceptual clarity is proposed.Two active surface wave testing cases are considered to validate the theory and method.The results indicate that(1)an accurate trigger system is not necessary for surface wave data acquisition,and(2)it is unnecessary to assume that the impact point is the generation point of the surface waves for the experimental dispersion analysis.展开更多
胎儿宫内、分娩时或产后,由细菌、病菌、霉菌等不同病原体引起的肺部疾病常引起新生儿呼吸衰竭直至死亡,及早确诊、正确评估对其治疗效果及预后具有重要价值[1-2]。床旁X线检查和CT是诊断新生儿肺部疾病的主要影像学手段,能较准确显示...胎儿宫内、分娩时或产后,由细菌、病菌、霉菌等不同病原体引起的肺部疾病常引起新生儿呼吸衰竭直至死亡,及早确诊、正确评估对其治疗效果及预后具有重要价值[1-2]。床旁X线检查和CT是诊断新生儿肺部疾病的主要影像学手段,能较准确显示肺脏病变范围及部位。但床旁X线胸片和CT检查确诊率较低,与新生儿体位限制有较大关系[3]。新生儿对电离辐射致癌性的敏感程度高于成人,也提示X线胸片和CT检查存在较大风险[4]。随着影像学的发展,超声被应用于肺部疾病诊断中,研究发现床旁超声可提高对肺部疾病诊断的准确率,且可检测出新生儿感染性肺炎(infectious pneumonia of newborn,IPN)与呼吸窘迫综合征(neonatal respiratory distress syndrome,NRDS)的区别[5]。另有研究发现IPN与湿肺(transient tachypnea of the newborn,TTN)或与胎粪吸入综合征(meconium aspiration syndrome,MAS)的差异性,通过床旁肺脏超声对鉴别诊断上述肺疾病的敏感性和特异性也较高[6]。本文旨在分析IPN、TTN、NRDS、MAS的肺脏超声图像,明确其差异特点,为临床诊断提供参考。展开更多
基金Natural Science Foundation of Hubei Province of China for Distinguished Young Scholars (2023AFA099)Natural Science Foundation of Hubei Province of China for Key Projects (Innovation Group) (2023AFA030)National Natural Science Foundation of China (52178471)。
文摘A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition.The effect of the trigger system on the dispersion image of surface waves is empirically known to be negligible,however,theoretical explanation regarding the effect of the trigger system is insufficient.This study systematically examines the theory for surface wave dispersion analysis and proves that the effect of the trigger system on a dispersion image is negligible via a solid theoretical explanation.Subsequently,based on the new theoretical explanation,an alternative method that uses only the relative phase difference between sensors to extract dispersion characteristics with better conceptual clarity is proposed.Two active surface wave testing cases are considered to validate the theory and method.The results indicate that(1)an accurate trigger system is not necessary for surface wave data acquisition,and(2)it is unnecessary to assume that the impact point is the generation point of the surface waves for the experimental dispersion analysis.
文摘胎儿宫内、分娩时或产后,由细菌、病菌、霉菌等不同病原体引起的肺部疾病常引起新生儿呼吸衰竭直至死亡,及早确诊、正确评估对其治疗效果及预后具有重要价值[1-2]。床旁X线检查和CT是诊断新生儿肺部疾病的主要影像学手段,能较准确显示肺脏病变范围及部位。但床旁X线胸片和CT检查确诊率较低,与新生儿体位限制有较大关系[3]。新生儿对电离辐射致癌性的敏感程度高于成人,也提示X线胸片和CT检查存在较大风险[4]。随着影像学的发展,超声被应用于肺部疾病诊断中,研究发现床旁超声可提高对肺部疾病诊断的准确率,且可检测出新生儿感染性肺炎(infectious pneumonia of newborn,IPN)与呼吸窘迫综合征(neonatal respiratory distress syndrome,NRDS)的区别[5]。另有研究发现IPN与湿肺(transient tachypnea of the newborn,TTN)或与胎粪吸入综合征(meconium aspiration syndrome,MAS)的差异性,通过床旁肺脏超声对鉴别诊断上述肺疾病的敏感性和特异性也较高[6]。本文旨在分析IPN、TTN、NRDS、MAS的肺脏超声图像,明确其差异特点,为临床诊断提供参考。
