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61.
In this work, a novel and simple phase-field-based lattice Boltzmann (LB) method is proposed for the axisymmetric two-phase electro-hydrodynamic flows. The present LB method is composed of three LB models, which are used to solve the axisymmetric Allen-Cahn equation for the phase field, the axisymmetric Poisson equation for the electric potential, and the axisymmetric Navier-Stokes equations for the flow field. Compared with the previous LB models for the axisymmetric Poisson equation, which can be viewed as the solvers to the convection-diffusion equation, the present model is a genuine solver to the axisymmetric Poisson equation. To test the capacity of the LB method, the deformation of a single leaky or perfect dielectric drop under a uniform electric field is considered, and the effects of electric strength, conductivity ratio, and permittivity ratio are investigated in detail. It is found that the present numerical results are in good agreement with some available theoretical, numerical and/or experimental data.  相似文献   
62.
63.
Summary The contours of pressure and flow of a pulse wave arriving at the entrance of a collapsed segment of an elastic tube can be described by application of the basic laws of reflection. The collapsed segment acts like a valve. It is opened by the pressure of the pulse wave when the pressure within the tube becomes higher than the collapse pressure, i.e. the pressure exerted on the segment from outside. This opening of the collapsed segment suddenly changes the sign of the pulse wave reflection from positive to negative; thus a typical contour change of the pulse proximal to the segment is observed. The most obvious effect is a reduction of the pulse pressure. The extent of this reduction is a function of the collapse pressure.A typical example of this phenomenon can be observed in an artery proximal to the segment which is collapsed due to the pressure exerted by an inflated Riva-Rocci cuff. The effect is explained by the assumption that the sign of reflection changes when the pressure of the pulse wave crosses the level of the cuff pressure. This explanation is supported by the results of model experiments.  相似文献   
64.
As the auscultatory method of blood pressure measurement relies fundamentally on the generation of the Korotkoff sound, identification of the responsible mechanisms has been of interest ever since the introduction of the method, around the turn of the century. In this article, a theory is proposed that identifies the cause of sound generation with the nonlinear properties of the pressure-flow relationship in, and of the volume compliance of the collapsible segment of brachial artery under the cuff. The rising portion of a normal incoming brachial pressure pulse is distorted due to these characteristics, and energy contained in the normal pulse is shifted to the audible range. The pressure transient produced is transmitted to the skin surface and stethoscope through deflection of the arterial wall. A mathematical model is formulated to represent the structures involved and to computer the Korotkoff sound. The model is able to predict quantitatively a range of features of the Korotkoff sound reported in the literature. Several earlier theories are summarized and evaluated.  相似文献   
65.
积分加权法评价磷化学烧伤实验病理的意义与应用   总被引:6,自引:0,他引:6  
目的:积分加权法在病理组织学检查中的应用,方法:在常规病理描述基础上,采用积分加权法将病理结果予以定量,综合评价致伤后实验动物的主要脏器,结果:实验动物同等面积的磷酸烧伤各脏器积分降低,钙治疗后则显著改善,均与其它方面报道的资料一致,结论:积分加以数值使各脏器损伤程度一目了然,对不同脏器间的损伤情况有可比性,从而有助于了解主要受损脏器与总体的关系以及药物的治疗效果。  相似文献   
66.
探讨改良式剖宫产术的临床价值。方法:采用香港周杰医师1991年创立的一套改式剖宫产术对50例产妇进行手术并与同期腹部横切口传统剖宫产术进行比较。结果:改良式剖宫产术所用时间短,术中出血小,术后排气暗暗科痛轻、产褥病发生率低。住院时间短,与对照组比较有明显差异。  相似文献   
67.
Background: Several collaborations in communicable disease surveillancehave developed between European Union member states. Involvementin these activities takes time and money. It is vital that collaborationsare established in areas most likely to be beneficial. An exercisewas undertaken to inform national surveillance centres and theEuropean Commission as to priority areas for the developmentof collaborations. Methods: A modified Delphi exercise was undertakenamongst the heads of centres with responsibilities for surveillanceat national level in the member states of the EU. Participantsdeveloped, agreed and ranked criteria for developing collaborations.A list of communicable diseases and syndromes was then rankedusing a Likert-type scale. Three rounds were undertaken. Betweenrounds, scores and a ranking were fed back showing where participantshad ranked items, compared to the overall mean and rank distribution.For the third round participants were asked to use a categoricalscale, nominating six or ten high priority disease areas. Results:Response rates were 87.5% for round 1, 44% round 2 and 87% round3. The low round 2 response rate appeared to be because respondentsdid not wish to alter their rankings. The six high priorityareas were outbreaks of gastroenteritis/food poisoning, CID/otherslow virus infections, serious imported diseases, legionellosis,antimicrobial resistance and tuberculosis. When participantsgave ten high priority areas meningococcal disease, travel advice,vaccination/immunization and influenza were also included. Thefinal lists were accepted at the meeting of participants. Conclusions:The process was successful in developing both a priority listand consensus.  相似文献   
68.
基于开发的计算机取样系统,采用SPSR法脉冲动态测试KD306型耐硫甲烷化催化剂的有效扩散系数。线性化和参数估值的结果吻合较好,证实:线性化简化是合理的,参数估值是可用于有效扩散系数。KD306型耐硫甲烷化催化剂的曲折因子为7.2。  相似文献   
69.
目的:光镜下观察单宁酸--氯化铁法媒染的肝内微血管构筑。方法:用单宁酸配制的混合媒染固定液灌流大鼠,取肝脏冰冻切片,入氯化铁溶液中呈色。结果:肝小叶中央静脉、肝血窦以及小叶间动、静脉、小叶下静脉均显示良好,肝小叶周边有很横断面的血窦,肝板较饱满,窦壁上有许多细丝缠绕。结论:单宁酸--氯化铁法可很好地显示肝内微血管构筑,小叶周边存在与中央静脉平行的血窦。  相似文献   
70.
目的:研究一种新的导管法测定肺循环血流量。方法:分离右侧颈外静脉,将塑料导管自右侧颈外静脉插入,经上腔静脉、右心房和右心室插入肺动脉。用上海产SJ—42型四导生理记录仪记录生理参数。结果:肺循环血流量可按公式QP=MPAP·△QMPAP-MPAP计算,式中△Q是每分钟自肺循环流入容量测定计的血量,算得的QP=29.62±3.73ml/min,在大鼠的肺循环血流量正常范围之内。结论:该方法精确而且操作简便  相似文献   
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