离心泵叶轮结构有限元分析

叶轮是泵的核心部分,泵的性能参数:流量、扬程、效率和特性曲线的形状等均与叶轮的设计有重要关系。通过对叶轮结构进行有限元分析,准确地得到了叶轮在载荷作用下的应力,为叶轮的强度计算提供了可靠依据。     

Numerical computations of the flow in a finite diverging channel

The flow in a finite diverging channel opening into a large space and resembling the experimental prototype of Putkaradze and Vorobieff （2006） was numerically investigated. The effects of the Reynolds number, initial condition, intersection angle, length of the wedge edges, and the outer boundary condition were examined. The numerical results showed that the flow in the wedge undergoes a change from symmetrical flow to unsymmetrical flow with a weak backflow, then a vortical （circulation） flow and finally an unsteady jet flow as the Reynolds number is increased for an intersection angle of 32° and a wedge edge of length 30 times the width of the inlet slit. For the unsteady flow, the jet attached to one side of the wedge constantly loses stability and rolls up into a mushroom-shaped vortex-pair near the outlet of the wedge. As the intersection angle is increased to 50°, a stable jet flow is observed as a new regime between the vortex and unsteady regimes. Both the intersection angle and the wedge length have negative effects on the stability of the flow, although the effect of the wedge length on the critical Reynolds number for the symmetry-breaking instability is not pronounced. The outer boundary condition was found not to affect the flow patterns inside the wedge significantly. At a certain Re regime above the onset of symmetry-breaking instability, the flows evolve into steady state very slowly except for the initial stage in the case of decreasing flow flux. Two different solutions can be observed within the normal observation time for the experiment, providing a possible explanation for the hysteresis phenomenon in the experiment.     

一维带有迁移的疟疾病和疟蚊数学模型的有限体积元方法

运用有限体积元方法对带有迁移的疟疾病与疟蚊数学模型进行分析,以一次元函数空间为试探空间,分段常值函数空间为检验函数空间,并且给出了L2估计.     

Development of a plastic injection molding training system using Petri nets and virtual reality

INTRODUCTIONAt present, plastic as a substitute for metals in products is the most important mainstay in industrial raw materials. Furthermore, plastic injection molding is one of the most common and versatile methods for mass production of complex plastic parts with excel-lent dimensional tolerance. Since the technology of injection molding has been widely applied in manu-facturing, training on injection molding is of great importance. The traditional approach is to consult some technica…     

基于Flash的生物虚拟实验室的开发

生物虚拟实验室的建设已成为学校生物教学信息化的一个重点,以一个中学生物实验为例,较为详细地说明了基于Flash的生物虚拟实验室的开发原则和开发过程,希望起到抛砖引玉的作用。     

有限元分析在平面框架内力计算中的应用

利用有限元分析软件ALGOR对平面框架进行竖向荷载作用下静力计算、动力模态及地震响应分析计算,并同手工计算方法进行了比较 如果计算的结构类型更为复杂,则有限元分析的优点更为突出     

Motion and orientation of cylindrical and cubic particles in pipe flow with high concentration and high particle to pipe size ratio

Lattice Boltzmann method was used to numerically investigate the motion and orientation distribution of cylindrical and cubic particles in pipe flow with high concentration and high particle to pipe size ratio. The transient impulse model of 3D collisions between particles and between particle and wall is proposed. The numerical results are qualitatively in agreement with and quantitatively comparable to the experiment data. The results show that the increases of both the cylindrical particle to pipe size ratio and the particle aspect ratio decrease the rotation about all axes. All rotations of cubic particles decrease with increasing the particle concentration. The cubic particles, rotating more drastically in the flow with large Reynolds number, rotate faster than the cylindrical particles with the same size. The cylindrical particles align with the flow direction more obviously with decreasing Reynolds numbers. However, the orientations of cubic particles are spread all over the range with no significant difference in magnitude, and the Reynolds numbers have no obvious effect on the orientations of cubic particles.     

二维光子晶体中光传输特性的数值模拟研究

本文将时域有限差分方法(FDTD)用于光子晶体理论研究,计算了光子晶体的透射率频率分布;并依据此透射率频率分布,直观地给出了不同频率段的光在二维方型完整光子晶体和有缺陷光子晶体中的一些传输特性。     

谐波齿轮传动柔轮位移场和应力场的有限元分析

本文对谐波齿轮传动柔轮位侈场和应力场用有限元方法进行了理论分析与实例验算。较真实和全面地揭示了柔轮在负载条件下变形和应力状态。这为柔轮的强度计算提供了可靠的依据。     

Design of capacitance sensor system for void fraction measurement

INTRODUCTION Oil-gas multiphase transport technology, in- cluding multiphase pressurization, multiphase flow- meter and multiphase flow control, has become very effective as an economic and reliable method for seabed oil exploitation. During the design of mixing transport system, prediction of pressure drop, heat transfer coefficients and void fraction is needed, so flow pattern identification is necessary. Among flow parameters, void fraction, defined as the cross section fraction occupie…     

基于Matlab的有限元结构内力分析

介绍了Matlab语言的特点,详细介绍了用MATLAB语言编制结构内力分析的有限元方法,并通过实例对平面框架结构进行了内力和位移分析.     

舰体侵彻破坏环境分析

导弹对舰船的破坏首先是弹体对舰体的侵彻,采用有限元法,建立适当的计算模型,利用大型有限元动力分析软件LS—DYNA对舰船遭受导弹等武器攻击的侵彻阶段进行数值实验研究,给出侵彻阶段舰船的破坏环境,非常具有实际意义,研究结果对开展相关研究具有一定的参考价值。     

某高层建筑结构动力特性研究

利用有限元分析软件ANSYS对某高层建筑结构进行模态分析,建立高层建筑结构的三维模型,研究该结构的动力特性,并将计算得到结构的自振周期同经验公式比较,探讨计算高层建筑结构自振周期的影响因素,结果表明两种计算方法结果十分接近,验证了有限元分析的正确性。     

一类均匀介质腔体模型电磁散射问题的快速求解算法

针对矩形腔体模型的散射问题,基于双线性元离散,提出了一种有效的快速求解算法.通过傅里叶变换和高斯消去法将离散方程简化为维数较低的界面方程,对界面方程给出了一个有效的预处理子空间迭代法,数值试验说明了算法的有效性.     

无机化学中元素化学教学的探讨

探讨元素化学教学中要密切联系社会生活,拉近化学与生活的距离,并通过古代化学、历史小故事的穿插以及环保意识的渗透,激发学生学习元素化学的兴趣。     

构建基于校园网的寓教于乐的虚拟社区探索

随着互联网的高速发展和普及,虚拟社区已经成了人们社会存在的一种不可忽视的新的形式,而基于校园网的虚拟社区是区别于一般商业性虚拟社区的一种特殊网络产物,随着越来越多的学生参与其中,它为高校的综合管理和教育提供了一种新的平台和机遇,该文结合桂林电子工业学院漓江夜话第二频道虚拟社区的建设和发展的实践,对如何有效利用网络实现“寓教于乐”的功能进行了探索。     

Finite element analysis of dynamic stability of skeletal structures under periodic loading

INTRODUCTION Some structures fail geometrically before thestrength failure because of lack of stability and such afailure is known as instability failure or bucklingfailure. Determination of buckling load is importantin order to ensure the stability of a structure. If thestructure under consideration is subjected to a dy-namic load then this problem comes under the pur-view of dynamic stability problems. Examples areslender offshore structures subjected to periodic ex-citations and colum…     

Simulating Experiment and Circuit Simulation of RTD/HPT Photo-Controlled MOBILE

Theresonanttunnelingdiode (RTD) [1] isahigh speednanoelectronicdevicebasedonquantumresonanttunnelingeffect.Ithastheadvantagesofhighspeed,highfrequency ,lowoperatingvoltage,low powerdissi pation,intrinsicbistabilityandself latchingduetoitsnegativedifferentialresistance .Comparedwithconven tionaldevice,ithasthefeatureofreducingthenumberofdevicesandcircuitcomplexityforachievingthesamelog icfunction .　　TheMOBILE[2 ,3 ] isalogicelementrealizingthemonostable bistabletransitionofacircuitthatcon…     

FVS0812铝合金半球形件包覆拉深的有限元分析

采用DEFORM-3D有限元分析软件对FVSO812铝合金半球形件在升温条件下的包覆拉深工艺进行了分析.结果表明:选用不同的包覆材料对工件产生的作用差异较大.包覆板选用双钢板时,拉深工艺极大改善了工件的应变和应力分布状态,降低甚至避免了拉深过程中发生断裂的危险性;对比实验结果,损伤区域的预测与实验结果相吻合.     

本科土建专业有限元法教学探讨

有限元法是一门理论与实际紧密联系的课程,由于要求学习者具备扎实的工程数学功底,目前本科生开设《有限元法》存在着一定难度。本科有限元法教学中要采用启发性教学等多种教学方法,利用有限元软件,加强与实际工程的紧密结合,使学生真正理解有限元方法,提高学生的综合应用能力,同时把握教学内容的难度和深度,采用多种考核方式,以培养学生能力为主。