平面K型主圆支方钢管节点力学性能数值分析

以平面K型主圆支方钢管节点的试验数据为基础,建立有限元参数分析模型,进行了非线性有限元参数分析。研究揭示了节点受力全过程,破坏模式以及分布规律。重点考察了支管边长与主管直径比值β、主管的径厚比γ和支管与主管的壁厚比τ对节点极限承载力的影响。有限元参数分析结果表明：主管的径厚比γ和支管与主管的壁厚比τ对节点极限承载力影响...     

基于CFD-DEM方法的柱状颗粒在弯管中输送过程的数值模拟

针对物料在气力输送过程中特别是弯管部分易破碎的问题,采用计算流体力学(CFD)和离散单元法(DEM)耦合模拟弯管内的柱状颗粒气力输送过程,对弯径比k分别为1、2、3、4、6的90°弯管内柱状颗粒的运动状态、碰撞特性、破碎原因及相关的力学特性进行研究。结果表明:球形颗粒与柱状颗粒在输送过程中遵循基本一致的变化规律,同样外部条件下,柱状颗粒的悬浮速度小于球形颗粒。当k=3时气力输送过程颗粒的破碎率最低。同时,颗粒与管壁的碰撞是造成颗粒破碎的主要原因。     

TDB－100硅太阳电池仿真及P－V特性研究

采用多项式数学模型对ＴＤＢ－１００硅太阳电池实测Ｉ－Ｖ数据进行拟合，可得到电池的实验模型，该模类具有很高的精度。运用这个模型对Ｐ－Ｖ特性进行分析，并根据电池的光照及温度特性，将该模型进行扩展，得到了电池的预计模型。     

Heat transfer and bubble characteristics in a fluidized bed with immersed horizontal tube bundle

The effect of gas velocity on the average and local heat transfer coefficients between a submerged horizontal tube (25.4 mm-OD) and a fluidized bed has been determined in a fluidized-bed-heat-exchanger (0.34×0.50×0.6 m-high) of silica sand particles. The heat transfer coefficients and the properties of bubble and emulsion phases were simultaneously measured at the same location around the tube circumference by thermocouples and an optical probe. The average heat transfer coefficient (h_avg) exhibits a maximum value with variation of gas velocity (U_g). The local heat transfer coefficient (h_i) exhibits maximum values at the side of the tube (0°). Bubble frequency (f_b) increases and the emulsion contacting time (t_e) decreases with increasing U_g. The h_i increases with increasing f_b and decreasing t_e. The f_b exhibits higher values and t_e is shorter at the bottom (under each side) than those at the top section of the tube. The t_e and bubble fraction (δ_b) have been correlated with Froude number. The predicted h_avg values of small particles based on the packet renewal model and the emulsion contacting characteristics around the tube well accord to the experimental data.     

水平轴风力机三维气动特性实验

以国外某公司的水平轴风力机产品为原型设计模型风力机，并搭建了风洞实验台，测定了风力机三维速度流场，为研究水平轴风力机关键气动问题做好准备，并初步获得风力机的进出口流场的实验数据。表明，所做的风洞实验基本反映了风力机的运行特点，捕捉到了叶片尾迹流动的基本特征，为进一步进行风力机的气动特性研究和设计高性能的水平轴风力机提供了保障。     

缸盖气道流量试验台设计

介绍缸盖气道流量试验台的结构、设计原理 ,以及设备试验的可靠性结果。     

应用最小二乘支持向量机和混合遗传算法的制粉系统优化控制

利用最小二乘支持向量机(LSSVM)对直吹式中速磨制粉系统进行建模,然后采用混合遗传算法(HGA)对模型寻优,以获得不同工况下制粉系统的最佳运行方式.在某电厂200 MW机组上进行了现场试验.结果表明:该方法具有较高的可靠性和实用性,可用以指导运行人员进行制粉系统的优化调整.     

Combined forced and free flow in a vertical circular duct subjected to non-axisymmetric wall heating conditions

The fully developed mixed convection flow in a vertical circular duct is investigated analytically, under the assumption of laminar parallel flow. A wall heat flux uniform in the axial direction and dependent on the angular coordinate is considered. As a consequence, the fluid temperature is three dimensional, since it changes in the radial, axial and angular directions. An analytical method based on Fourier series expansions of temperature and velocity fields is adopted to determine the velocity and the temperature distributions as well as the friction factor and the average Nusselt number. The general solution, expressed in terms of Bessel functions, is applied to study a case that has a special importance in technical applications: a duct whose wall is half subject to a uniform heat flux and half adiabatic. The positive and negative threshold values of the ratio between the Grashof number Gr and the Reynolds number Re for the onset of the flow reversal phenomenon are determined. A comparison between the average Nusselt number for the considered non-axisymmetric case and that for the case of a duct subject to a uniform wall heat flux is performed.     

Global space–time multiquadric method for inverse heat conduction problem

In this paper, a radial basis collocation method (RBCM) based on the global space–time multiquadric (MQ) is proposed to solve the inverse heat conduction problem (IHCP). The global MQ is simply constructed by incorporating time dimension into the MQ function as a new variable in radial coordinate. The method approximates the IHCP as an over‐determined linear system with the use of two sets of collocation points: one is satisfied with the governing equation and another is for the given conditions. The least‐square technique is introduced to find the solution of the over‐determined linear system. The present work investigates two types of the ill‐posed heat conduction problems: the IHCP to recover the surface temperature and heat flux history on a source point from the measurement data at interior locations, and the backward heat conduction problem (BHCP) to retrieve the initial temperature distribution from the known temperature distribution at a given time. Numerical results of four benchmark examples show that the proposed method can provide accurate and stable numerical solutions for one‐dimensional and two‐dimensional IHCP problems. The sensitivity of the method with respect to the measured data, location of measurement, time step, shape parameter and scaling factor is also investigated. Copyright © 2010 John Wiley & Sons, Ltd.     

谈城市广场设计的生态性和文化性——以深圳华侨城生态广场、罗湖区创意文化广场为例

城市广场是城市设计的重要组成部分.通过分析深圳华侨城生态广场、罗湖区创意文化广场的设计.浅谈城市广场的生态设计和文化设计.其设计理念、设计手法以及成功经验对于建设其他城市绿色空间、提高城市建设质量值得借鉴.