Pulsed Umbilical Artery Doppler Ultrasound Findings in Management of High-Risk Term Pregnant Women during Labour

Purpose: Intrapartum Doppler velocimetry is a non-invasive investigation method. This method is useful for evaluating the pathophysiological mechanisms underlying changes in fetal heart rate. This study aimed to determine the usefulness of Doppler ultrasound findings during labor in high-risk women on determining the mode of delivery and outcome of the newborn. Methods: A cross-sectional study was conducted from January 1, 2015 to December 31, 2015 on 100 high-risk pregnant women during labor. The study was performed in the Maternity Teaching Hospital in Erbil City, Kurdistan Region, Iraq. Results: The majority of women (77%) had a normal end-diastolic blood flow pattern through the umbilical artery. A total of 76.9% of those with abnormal Doppler results had a Cesarean delivery compared with only 9.5% of those with normal Doppler results (p p p = 0.07) and fifth minutes (p = 0.01). Conclusions: Abnormal umbilical artery Doppler ultrasound findings in high-risk pregnancies for women in labor are associated with increased rates of emergency cesarean sections and a poor outcome of the newborn.

超声多普勒测速仪在液-固和气-液两相流测量中的应用

This work aims to investigate the application of ultrasound Doppler velocimetry in multiphase flow.The experimental results show that in the homogeneous liquid-solid system,the amplitude of the received echo energy decreases exponentially with measurement depth,and attenuation rate increases with increase of solid holdup monotonously.A model based on the ultrasound reflection and refraction law and scatter characteristics of particles is proposed to predict the relationship between received echo energy and solid holdup.In the gas-liquid system,liquid velocity and bubble rise velocity can be directly obtained from the velocity profile by Dop 2000 when the bubble number is small,while in medium gas velocity range,FFT must be executed to calculate velocity distribution, resulting in a two-peak distribution,which in turn can be used to obtain liquid velocity and bubble velocity by further data processing.

液固循环流化床中颗粒轴向速度的实验研究

利用超声多普勒测速仪实验测量了液固循环流化床中不同径向位置处颗粒瞬态轴向速度,研究了其概率密度分布特征。采用瞬态速度的标准偏差衡量瞬态速度的波动程度,考察了不同操作形式下的颗粒时均轴向速度的径向分布以及表观液速和颗粒循环速率等操作条件对速度波动程度和速度均值径向分布的影响。利用相间作用力对两种分布的特点进行了机理分析,并对液固和气固循环流化床中颗粒的流动行为进行了比较。

管内垂直下降液膜速度与厚度分布特性

对洗涤冷却管内垂直降膜的流动特性进行研究,采用超声波多普勒测速仪对管内不同周向以及轴向位置的液膜厚度和速度进行了无接触式的测量,液膜Reynolds数范围为1.0×10~4~3.1×10~4。结果表明：在0°周向位置上液膜厚度与速度均达到最大值,导致该位置局部液膜厚度过大而不能保持稳定,部分液体脱离液膜表面,此外还造成了8°和16°位置的液膜厚度激增。在轴向上,当Reynolds数小于2.0×10~4时,液膜速度在重力作用下随流动距离增加而增加,反之,液膜速度因为流动阻力会随距离增加而减小。随着Reynolds数的增大,液膜平均厚度和速度呈增大趋势。此外,Reynolds数的增大还会使得液膜更加不稳定。

11~13^(+6)孕周正常胎儿静脉导管血流频谱参数分析

目的测量分析在11~13+6孕周正常胎儿静脉导管(ductus venosus,DV)各血流频谱参数与孕周的关系,建立各自参考曲线。方法选取11~13+6孕周在我科行超声检查的单胎孕妇904例,进行胎儿DV多普勒血流检查,分别测量心室收缩期血流峰值(S-wave)、心室舒张早期血流峰值(D-wave)、心房收缩期血流速度(A-wave)、平均时间最大血流速度(time-average maximum velocity,TAMXV)、搏动指数(pulstility index,PI)、前负荷指数(preload index,PLI)、心室收缩期血流峰值/心房收缩期血流速度(S/A)。随访妊娠结局,503名正常妊娠孕妇纳入研究。结果 S-wave(r=0.237,P<0.01)、D-wave(r=0.251,P<0.01)、A-wave(r=0.217,P<0.01)、TAMXV(r=0.272,P<0.01)与孕龄显著正相关,PI(r=-0.159,P=0.006)与孕龄显著负相关,PLI(r=-0.096,P=0.098)、S/A(r=-0.089,P=0.128)与孕龄无相关性。结论孕早期胎儿DV血流速度随孕周增加而增加,PI随孕周增加而降低,PLI和S/A无显著变化。

液态铅铋合金流动速度场测量技术研究

液态铅铋合金是先进反应堆-加速器驱动的次临界系统(ADS)优选的靶材和冷却剂材料,液态铅铋流动速度场的测量是优化堆芯组件分布以及靶窗结构的一种重要手段。同时,冷却剂流动速度也是反映反应堆热工水力特征的重要参数之一。本文采用实验研究的方法,设计旋转搅动装置,通过对常温水与液态铅铋的流动速度场测量,验证了超声多普勒测速技术用于液态铅铋合金速度场测量的可行性。

气液降膜流动厚度及流速分布特性

对洗涤冷却管内垂直降膜的流动特性进行了研究,采用超声波多普勒测速仪,对气相影响下液膜的厚度和速度进行了无接触式的测量,实验液膜雷诺数为2.04×10~4,气相雷诺数范围0~6.83×10~4。结果表明:液膜在洗涤冷却管流动发展过程中明显存在中央液膜向两边铺展的现象,铺展规律受气相雷诺数及出口槽缝尺度影响显著。管内周向角8和16°处局部液膜波动较其余周向位置剧烈并有增厚的趋势,且气相雷诺数和槽缝宽度的增大均使这两处液膜增厚位置向后延迟,使得管内初始段膜厚变薄。此外,气相雷诺数增大加强气液两相间的剪切作用,整体上加剧了液膜波动幅度,液膜速度波动趋势更加显著。

电磁场下液态金属流速的测量技术分析

由于金属液的不透明性和电磁场作用的特殊性,传统测量技术无法测定液面及内部流场结构。为此,开发了适用于电磁场下液态金属流速的测量技术。结合电磁场作用下液态金属行为测量的需求,介绍了几种测量技术的原理、优缺点和应用场合,给出了选用测量技术的依据,并探讨了当前测量技术在高温、时序控制和大体积等方面的应用难点,分析了电磁场作用下液态金属测量技术的研究方向。电磁场下液态金属流速的测量技术发展,将促进金属凝固理论和电磁约束成型工艺的创新,有利于研究电磁场对聚能射流形态的影响。

UDV非接触式测量的壁效应及其校正模型

为了校正商用超声 Doppler测速仪由于没有考虑壁效应而在 Doppler角度和测量位置的确定上引起的较大误差 ,对超声 Doppler测速仪 (UDV)在非接触式测量的壁效应进行了实验研究。从超声传播和界面折射的基本规律以及测量体积的基本概念出发 ,利用系统提供的时间信息 ,建立了壁效应的校正模型。应用此模型对系统软件给出的Doppler角度和测量位置进行校正 。

电磁搅拌对钢包精炼炉内金属液行为的影响

以侧壁配备电磁搅拌系统的钢包精炼炉为背景,分别利用多普勒超声波测速仪以及激光液位仪对几种电磁搅拌方式下金属液的内部流动以及表面波动状况进行了测定及分析。研究发现,电磁搅拌可以有效促进金属液的内部流动以及表面波动,从而显著改善金属液内部的动力学条件,是提高钢包精炼效率的有效手段;不同电磁搅拌方式对金属液的内部动力学条件影响的差异明显,在不同的精炼工艺要求下,可以考虑采用不同的电磁搅拌方式。

Effect of Linear Electromagnetic Stirring on Behavior of Liquid Metal and Rate of Slag-Metal Interfacial Reactions

The internal flow,free surface shape,and level fluctuation of liquid metal exposed to linear electromagnetic stirring were measured and analyzed against the background of an actual metallurgical equipment with linear electromagnetic stirring system.The desulphurization process,with or without imposition of linear electromagnetic stirring,was also studied experimentally.The changes in sulfur content of hot metal with respect to time were obtained,and the volumetric mass transfer coefficients corresponding to different stirring currents were determined.The results showed that linear electromagnetic stirring can effectively promote internal flow,effectively increase the level fluctuation,and significantly improve the kinetic condition of liquid metal.The internal flow and level fluctuation of liquid metal increase in line with the increase in electromagnetic stirring intensity.The desulphurization experiments show that linear electromagnetic stirring can significantly promote the desulphurization process of hot metal,and that the technology has wide application potential in promoting various slag-metal reactions.