大口径方锥体形风道设计结构改进

对大口径方锥体形风道的设计结构进行了改进,提出对于长宽比例较大的风道应将导向板与外部加固肋的设计进行综合考虑,借助导向板将单一风道分隔成多腔体,使导向板承担导流和拉力载荷的双功能,这样设计可以大幅度减小外部加固肋和风道壁板的规格。利用Solidworks软件建立优化前和优化后的结构模型,进行有限元分析,对比在设计压力下的分析结果。结论认为优化后的结构应力值低,变形量很小,可节约材料50%以上。

折边锥体形夹套封闭件的受力计算和探讨

夹套压力容器是一种普遍应用的多腔类压力容器,其夹套封闭件是连接容器和夹套的主要受压元件。夹套在受内压工况、温差工况以及重力载荷工况时,分别参考并运用相应的计算方法对折边封口锥进行强度校核计算和分析对比。结果表明,各种载荷工况的影响均不可忽视,只有受力计算和分析越详细,才能更大限度地降低设备在使用过程中可能存在的一切安全隐患和风险。

甲状腺功能异常有哪些表现

甲状腺是人体最大的内分泌器官,它虽然体积小,但功能较强大,被形容为“人体的发动机”。下面我们就来认识一下甲状腺。甲状腺的形态、位置甲状腺位于颈前部,颜色为棕红色,呈“H”形,蝴蝶状,重约20~30克;由左右两叶、峡部及锥状叶组成。甲状腺左右叶呈锥体形(右叶稍大),贴于喉和气管的侧面,由于其形似盾甲,故名甲状腺。当我们在做仰头吞咽时,甲状腺会上下移动,正常情况下,甲状腺是看不到,也摸不到的。

颌面颈部疾患的超声成象

一、解剖生理 (一)涎腺(Salivarg gland)又称唾液腺,具有分泌唾液湿润口腔粘膜,协助消化、杀菌、调和食物便于吞咽等作用。包括三大对大的唾液腺:腮腺、颌下腺以及舌下腺和无数分布于舌、颊、腭等处的小涎腺。 1.腮腺(Parotid)是涎腺中最大的一对,成人宽约3～4cm,厚数mm～1cm许,重约15～30g,位于颜面二侧,颧弓之下,外耳道的前下方,乳突之前,嚼肌表面,下颌支的后方,其下端在下颌角的后下方。整个腮腺有似倒立的锥体形,尖向下,底朝上。有前、后、外三个面。

滦平县发现元代窖藏

1978年4月,滦平县付营子乡凡西营村猪厂修管道时,距地表一米深处发现一件口径39厘米,通高1.1米的绿釉大瓷缸。口盖圆形石板。此缸小口,大腹、小底,呈圆锥体形,

胡琴鉴赏

红木卷书琴首高音板胡板胡又称梆胡、秦胡、胡胡、呼胡、大弦和瓢,我国民族弓拉弦鸣乐器,因琴筒蒙桐木薄板得名。明末清初随着地方戏曲梆子腔的兴起而流行,流行于西北、华北、东北各省区,尤以陕西、甘肃、山西等省最为盛行。图1所示为高音板胡,板胡琴杆用红木制成,为圆柱形,长约73cm,琴头上端方形,下设二圆锥体形弦轴。

Existence and uniqueness of a class of double pyramidal central configurations in six-body problems

Under the necessary conditions for a double pyramidal central configuration with a diamond base to exist in the real number space, the existence and uniqueness of such configurations were studied by employing combinedly the algebraic method and numerical calculation. It is found that there exists a planar curl triangle region G in a square Q such that any point in G and given by the ratio of the two diagonal lengths of the diamond base and the ratio of one diagonal length of the base to the height of the double pyramid configuration determines a unique double pyramid central configuration, while all points in Q-G have no referance to any central configuration.

CFD-DEM simulation of fluid-solid flow of a tapered column separation bed

Research on recycling waste Printed Circuit Boards(PCB) is at the forefront of preventing environmental pollution and finding ways to recycle resources.The Tapered Column Separation Bed(TCSB) is invented aiming at disposing the problem that fine particles of waste printed circuit boards cannot be separated efficiently so as to obtain further insight about the underlying mechanisms and demonstrate the separation feasibility in the tapered column separation bed.In this work,a Computational Fluid Dynamics(CFD) coupled with Discrete Element Method(DEM) model for two-phase flow has been extended to simulate the fluid-solid flow in the tapered column separation bed.Its validity is demonstrated by its successful capturing the key features of particles' flow pattern,velocity,the pressure distribution,the axial position with time and axial force for particles with different densities.Simulation results show that the plastic particles and resin particles become overflow,while copper particles,iron particles and aluminum particles successively become underflow,with a discharge water flow rate of 1 m^3/h,an obliquity of 30°.The simulated results agree reasonably well with the experimental observation.Using this equipment to separate waste PCBs is feasible,theoretically.

Early-Time High-Altitude Electromagnetic Pulse Environment(E1) Simulation with a Bicone-Cage Antenna

The simulation of the early-time High-altitude Electromagnetic Pulse （HEMP） environment （El） with bicone-cage antenna in free space requires utilization of the spherical wave to reproduce the boundless plane wave. The transient radiation of the antenna above the lossy ground is computed using the Finite-Difference Time-Domain （FDTD） method The determining factors of the field waveform are explored and analysed on the basis of the physical evolution process of the transient radiation. The typical waveform of the electric field and the field distribution characteristics, both of which are important for HEMP simulator design and the effect tests, are presented. The study indicates that the simulation should be analysed from the perspective of both environment building and simulator applications.

Comparison of numerical simulations and experiments in conical gas–solid spouted bed

Flow behavior of gas and particles in conical spouted beds is experimentally studied and simulated using the twofluid gas-solid model with the kinetic theory of granular flow.The bed pressure drop and fountain height are measured in a conical spouted bed of 100 mm I.D.at different gas velocities.The simulation results are compared with measurements of bed pressure drop and fountain height.The comparison shows that the drag coefficient model used in cylindrical beds under-predicted bed pressure drop and fountain height in conical spouted beds due to the partial weight of particles supported by the inclined side walls.It is found that the numerical results using the drag coefficient model proposed based on the conical spouted bed in this study are in good agreement with experimental data.The present study provides a useful basis for further works on the CFD simulation of conical spouted bed.

Existence and uniqueness for a class of nine-bodies central configurations

On some necessary conditions for double pyramidal central configurations with concave heptagon for any given ratio of masses, the existence and uniqueness of a class of double pyramidal central configurations with concave heptagon base for nine-body problems is proved in this paper, and the range of the ratio cr of the circularity radius of the heptagon to the half-height of the double pyramidal central configuration involved in this class configurations is obtained, which is in the interval （√3/3,1.099 600 679）, and the configuration involved in the bodies with any σ∈ （√3/3, 1.099 600 679） can form a central configuration which is a uniquely central configuration is proved.

Existence and uniqueness for a class of double pyramidal central configurations with a concave pentagonal base

Based on some necessary conditions for double pyramidal central configurations with a concave pentagonal base, for any given ratio of masses, the existence and uniqueness of a class of double pyramidal central configurations with a concave pentagonal base in 7-body problems are proved and the range of the ratio between radius and half-height is obtained, within which the 7 bodies involved form a central configuration or form uniquely a central configuration.

HEAT AND MASS TRANSFER EFFECTS ON CARREAU FLUID MODEL FOR BLOOD FLOW THROUGH A TAPERED ARTERY WITH A STENOSIS

In the current critique, we deliberate the blood flow through narrowing vein with a steno- sis in the manifestation of heat and mass transmission. The non-Newtonian flora of blood in small veins are examined mathematically by demonstrating the blood as Carreau fluid. The illustration for the blood flow is debated through an axially irregular but outward regular stenosis. Regularity in the dissemination of the fortification clipping stress and resistive impedance and their evolution with the emerging stenosis is a new significant feature of our investigation. Analytical solutions have been appraised for ＂velocity, tem- perature, concentration, resistance impedance, wall shear stress and shearing stress at the stenosis throat＂. The graphical consequences of different types of tapering arteries （i.e. ＂converging tapering, diverging tapering, non-tapered artery＂） have been studied for dissimilar constraints of attention. Rivulet shapes have been strategized for different parameters at the culmination of the article.

Integrated Optical Waveguide Sensor for Lighting Impulse Electric Field Measurement

A Lithium niobate （LiNbO3） based integrated optical E-field sensor with an optical waveguide Mach-Zehnder interferometer （MZI） and a tapered antenna has been designed and fabricated for the measurement of the pulsed electric field. The minimum detectable E-field of the sensor was 10kV/m. The sensor showed a good linear characteristic while the input E-fields varied from 10kV/m to 370kV/m. Furthermore, the maximum detectable E-field of the sensor, which could be calculated from the sensor input/output characteristic, was approximately equal to 1000kV/m. All these results suggest that such sensor can be used for the measurement of the lighting impulse electric field.

The Blood Flow of Prandtl Fluid Through a Tapered Stenosed Arteries in Permeable Walls with Magnetic Field

This Communication deals with the blood flow of Prandtl fluid through a tapered stenosed arteries having permeable walls.The governing equations of two-dimensional Prandtl fluid model are modelled in cylindrical coordinates.The highly nonlinear equations are simplified with the help of non-dimensional variables under the assumption of mild stenosis.The solution of reduced nonlinear equation subject to boundary condition of porous walls having the effects of Darcy's number and slip parameter are computed analytically with the help of perturbation method.Effects of emerging parameters such as impedance A,slip parameter a,stenosis height 6,magnetic parameter and stress component Srz on velocity are illustrated graphically.The streamlines have also been presented to discuss the trapping bolus discipline.

Perturbation analysis for pulsatile flow of Carreau fluid through tapered stenotic arteries

The pulsatile flow of blood in a tapered narrow artery with overlapping time-dependent stenosis is mathematically analyzed, modeling blood as Caxreau fluid. Perturbation method is employed for solving the resulting nonlinear system of equations along with the appropriate boundary conditions. The analytic solutions to the pressure gradient, velocity distribution, flow rate, wall shear stress and longitudinal impedance to flow axe obtained in the asymptotic form. The variation of the aforesaid flow quantities with respect to various physical parameters such as maximum depth of the stenosis, angle of tapering of the artery, power law index, Reynolds number, pulsatile amplitude of the flow and Weissenberg number is investigated. It is found that the wall shear stress and longitudinal impedance to flow increase with the increase of the angle of tapering of the artery, the maximum depth of the stenosis and pulsatile Reynolds number and these decrease with the increase of the amplitude of the flow, power law index and Weis- senberg number. The mean velocity of blood decreases significantly with the increase of the artery radius, maximum depth of the stenosis, angle of tapering of the artery.

Peristaltic transport of a MHD Carreau fluid in a tapered asymmetric channel with permeable walls

The effect of permeable walls and magnetic field on the peristaltic flow of a Carreau fluid in a tapered asymmetric channel is studied. The tapered asymmetric channel is normally created due to the intra-uterine fluid flow induced by myometrial contractions and it was simulated by asymmetric peristaltic fluid flow in a two-dimensional infinite non-uniform channel. The analysis has been performed under long wavelength and low- Reynolds number assumptions to linearize the governing flow equations. A series solution in respect of a small Weissenberg number is obtained for the stream function, axial pressure gradient and shear stress. Time average of pressure rise and frictional force on the upper wall has also been computed using numerical integration. The results have been presented graphically for the various interested physical parameters. It is observed that for Carreau fluids the peristalsis works as a pump against a greater pressure rise compared with a Newtonian fluid, while there exists no significant difference in free pumping flux for Newtonian and Carreau fluids in the tapered asymmetric channel.

Blood flow of Carreau fluid in a tapered artery with mixed convection

This research is concerned with the mathematical modeling and analysis of blood flow in a tapered artery with stenosis. The analysis has been carried out in the presence of heat and mass transfer. Constitutive equation of Carreau fluid has been invoked in the mathematical formulation. The representation of blood flow is considered through an axially non-symmetrical but radially symmetric stenosis. Symmetry of the distribution of the wall, shearing stress and resistive impectartce and their growth with the developirtg stenosis is given due attention. Solutions have been obtained for the velocity, temperature, concentration, resistance impedance, wall shear stress and shearing stress at the stenosis throat. Graphical illustrations associated with the tapered arteries namely converging, diverging and non-tapered arteries are examined for different parameters of interest. Streamlines have been plotted and discussed.

Simulation,experimental evaluation and performance improvement of a cone dielectric elastomer actuator

Dielectric elastomer actuators (DEAs) are an emerging class of polymer actuation devices and have extensive application prospect in the field of robotics because of their light weight, high efficiency and large deformation. A cone DEA is manufactured and its working principle is analyzed. To obtain the deformation of elastomer and movement of DEA in advance, a finite element method (FEM) simulation is performed first. According to the working principle, two working equilibrium points of DEA, corresponding to the displacements of DEA with voltage off and on, are obtained and validated by experiments, thus work output in a workcycle is computed. Experiments show that the actuator can respond quickly when voltage is applied and can return to its original position rapidly when voltage is released. Simulation results agree well with experimental ones and the feasibility of DEA simulation is proved, and causes for the small difference between them in displacement output are analyzed. The performance of the actuator is improved from the aspects of both displacement and force output. A diamond four-bar linkage mechanism is used as the preload part and a displacement output of 17 mm is obtained. The force output of one actuating unit is about 1.77 N, so three actuating units are assembled in parallel and the force output is heightened to as high as 5.07 N.