菲涅耳波带片成像时的像点分析

菲涅耳波带片可使入射光会聚起来，产生极大的光强，使点光源形成一系列的实像点和虚像点，其作用如同透镜成像。利用半波带分析法可分析菲涅耳波带片对称轴上的点光源通过菲涅耳波带片成像时像点在对称轴上的分布及 焦距的变化情况。     

素描教学的重新认识--关于动画专业素描教学

目前,我国大部分艺术类院校都开设了动画专业,如何做好动画专业的素描教学工作,是亟待思考和解决的问题.素描不仅仅是观察和表现手法的升华,更主要的是思维方式质的变化.     

基于声腔模态分析的汽车低频噪声优化

根据汽车白车身结构有限元模型建立车身声固耦合模型。基于声学模态分析理论,进而求解声腔模态。通过实车怠速噪声和车身悬置激励力测试车内响应点的声压值,进一步验证声固耦合模型。通过峰值频率下的板块单元贡献量和模态应变能优化分析,汽车车内低频噪声降低,有利于提升汽车的NVH性能。     

磁场中导电矩形薄板1∶3内共振下的超谐波动力学响应

针对横向恒定磁场中一边固定三边简支的导电矩形薄板,研究1∶3内共振条件下系统发生超谐波共振时的动力学响应。利用伽辽金法得到两自由度非线性振动微分方程组,并通过数值计算得到系统发生超谐-内联合共振时前两阶模态的响应图。结果表明,内共振的存在使得高阶模态被间接激发,不同参数下系统呈现出混沌、概周期运动等复杂动力学响应,可以通过调节磁场强度控制系统振动。     

Detection of preanalytical errors in arterial blood gas analysis

IntroductionBlood gas analysis (BGA) is an essential test used for years to provide vital information in critically ill patients. However, the instability of the blood gases is a problem. We aimed to evaluate time and temperature effects on blood gas stability.Materials and methodsArterial blood was collected from 20 patients into syringes. Following BGA for baseline, syringes were divided into groups to stand at 4°C and 22°C for 30, 60, 90, 120 minutes. All were tested for pH, partial pressure of carbon dioxide (pCO₂), partial pressure of oxygen (pO₂), oxygen saturation (sO₂), oxyhemoglobin (O₂Hb), sodium, potassium, glucose, lactate, oxygen tension at 50% hemoglobin saturation (p50), and bicarbonate. A subgroup analysis was performed to detect the effect of air on results during storage. Percentage deviations were calculated and compared against the preset quality specifications for allowable total error.ResultsAt 4°C, pO₂ was the least stable parameter. At 22°C, pO₂ remained stable for 120 min, pH and glucose for 90 min, lactate and pCO₂ for 60 min. Glucose and lactate were stable when chilled. Air bubbles interfered pO₂ regardless of temperatures, whereas pCO₂ increased significantly at 22°C after 30 min, and pH decreased after 90 min. Bicarbonate, sO₂, O₂Hb, sodium, and potassium were the unaffected parameters.ConclusionsCorrect BGA results are essential, and arterial sample is precious. Therefore, if immediate analysis cannot be performed, up to one hour, syringes stored at room temperature will give reliable results when care is taken to minimize air within the blood gas specimen.     

关于小周期板块训练模式的理论建构

研究了近年来运动训练中运用较多的小周期理论的内涵、训练安排及板块结构理论的内涵、训练安排,在此基础上提出了新颖的竞技训练模式——小周期板块训练模式。其内涵为:全年以预定的赛间间隔为小周期来制定训练计划,在小周期末参加比赛,以赛带练,赛练结合;根据不同运动员在训练或比赛中的重点问题为训练板块,一个板块解决一个问题,围绕具体板块安排训练的课次、方法和手段,使运动员在自己的板块中接受单一、集中的刺激,其外延为:小周期板块训练模式是微观的具体训练操作,依然有宏观的长期规划;比赛在这不仅仅是训练的目的,也是训练的一种手段;训练的关键是使赛季中形成且波动的竞技状态在每个小周期末都得到回升,达到较高水平,从而使高水平运动员适宜竞技状态在赛季中持续更长时间。     

美学原则在活动义齿制作过程中的应用

义齿不仅是一件符合生物力学的实用工具,还应是一件富于美的工艺品.运用形式美学法则指导义齿修复工作,则能更完美地完成义齿修复体.作者根据自身的临床工作经验,并结合国内外学者在此领域的研究成果,从人工牙的选择、排列及固位体和基托制作等方面,对义齿在制作过程中所应用到的美学原则和操作方法加以总结和归纳,便于更好的指导临床工作.     

Shear capacity of reinforced concrete columns strengthened with CFRP sheet

INTRODUCTION There is increased need in recent years for strengthening or rehabilitation of existing reinforced concrete structures adversely affected by overloading, construction material deterioration, seismic loads, structural deformation, etc. An effective method for increasing the shear capacity of reinforced concrete columns is the use of externally bonded carbon fiber reinforced plastic (CFRP) systems (ACI, 2002). FRP systems were first applied to reinforced concrete col-umns i…     

聚合物多元醇改善普通聚氨酯软泡压陷的性能研究

为了改善普通聚氨酯软泡的压陷性能，采用添加聚合物多元醇，并对照其添加前后的物性。研究结果表明：聚合物多元醇能有效地提高聚氨酯软泡的压陷性能。     

塑料异型材挤出成型模具建模和仿真技术

阐述了塑料异型材挤出成型模具在设计与制造中的建模和仿真的基本方法,指出产品开发过程及塑料挤出成型模具的仿真和虚拟样机及虚拟制造技术是加快开发塑料挤出成型新产品步伐的必由之路.