局部水头损失对明渠非均匀流水面曲线的影响

对于有局部阻碍的明渠恒定非均匀流，考虑局部水头损失后的水面曲线变化的研究目前比较少，局部水头损失的表达式也不统一。这不仅不便于统一确定局部水头损失系数，也不便进行考虑局部水头损失后的明渠恒定非均匀流水面曲线变化规律的定性分析。通过对缓坡明渠上的水面曲线进行试验和数值计算研究发现，当水流通过局部障碍物时，缓坡明渠水面曲线为有局部下降的a1型壅水曲线。     

Performance analysis of banyan-type multistage interconnection networks under nonuniform traffic pattern

Multistage Interconnection Networks(MINs) have a number of applications in the areas of computer and communications. The most widely researched structure among MIN’s is the (l)banyan type network. It has several variations such as buffered banyan, batcher-banyan, tandem banyan, recirculating banyan and banyan with contention resolution phase. Analytical performance evaluation is crucial for justifying the merit of the design in different operational conditions. While several analytical models have been proposed for the performance evaluation of MINs, they are mainly for uniform traffics. Even the models for nonuniform traffics have several shortcomings such as they only consider output buffered structure or do not consider blocking conditions. In this paper, the more accurate models than any other ones so far have been proposed for the performance evaluation of multibuffered banyan-type MIN’s under nonuniform traffic condition is obtained. The accuracy of proposed models are conformed by comparing with the results from simulation. Firstly, single buffer model is developed. Markov chain is used for the analysis. Multibuffer model is obtained from single buffer model. Simulation is performed using Discrete Evenet Simulaton(DES) method. As a results, proposed model proves to be very accurate.     

温度、材料不均匀性对粘塑性材料冲击拉伸失稳的影响──有限元模拟分析

本文采用具有过应力特征的热粘塑性本构方程，对冲击载荷作用下轴对称圆棒光滑试件的绝热失稳及变形快速局部化产生的原因和发展过程进行了有限元计算模拟分析。为了模拟实际材料中存在的不均匀性，义中考虑了材料热物性、热软化率及材料应变硬化特性三种简化的不均匀性情形对热粘塑性材料的绝热失稳过程的影响。     

Analytical layerwise solution of nonlinear thermal instability of SMA hybrid composite beam under nonuniform temperature condition

Abstract

Thermal buckling and post-buckling behavior of composite beam reinforced with shape memory alloy (SMA) wires under nonuniform temperature distribution is explored. Thermo-mechanical behavior of SMA wires is formulated by using the one-dimensional Brinson SMA model. Considering von Karman strain–displacement relation, corresponding nonlinear governing equations are obtained and solved analytically. Heat conduction equation is employed and through-the-thickness temperature distribution is obtained by discretization scheme of layerwise method. Influence of SMA-wire positioning across the thickness, temperature distribution, SMA wire pre-straining level and volume fraction of SMAs upon the thermal buckling and post buckling of reinforced beam are examined and discussed in detail.     

不均匀加热与节流对平行通道不稳定性的影响

为研究反应堆内轴向热流不均匀分布、径向不均匀加热和入口节流对密度波不稳定的影响,利用RELAP5/MOD4.0程序对强迫循环平行通道系统进行数值模拟. 由程序中的非平衡非均相模型和半隐式数值格式所得计算结果与实验数据符合较好. 对比轴向热流线性分布及余弦分布工况下的流动不稳定边界,并做出积分热流沿通道长度的变化曲线以分析其机理,还获取了径向不均匀加热与入口节流工况下系统和通道的临界相变数. 结果表明:轴向热流不均匀分布时系统的稳定性取决于沸腾边界的位置以及积分热流沿通道的分布. 与轴向热流均匀分布相比,轴向热流线性增大或减小分别使系统稳定性增强或减弱;入口过冷度较低时,轴向热流余弦分布提高系统稳定性;入口过冷度较高时,系统稳定性可能增强也可能减弱. 与轴向热流余弦分布相比,峰值偏向入口或出口分别会降低或提高系统稳定性. 径向不均匀加热对系统稳定性影响较小. 增大径向入口节流不均匀性时系统稳定性有减小的趋势,增大任一通道入口节流系数均可提高系统的稳定性.     

Nonlinear thermoelastic deflection of temperature-dependent FGM curved shallow shell under nonlinear thermal loading

The geometrically nonlinear thermomechanical transverse deflection responses of the functionally graded curved structure under the influence of nonlinear thermal field are reported in this article. For the numerical analysis, a nonlinear mathematical model is derived using the higher-order shear deformation theory and Green–Lagrange nonlinear strains. The current model includes all of the nonlinear higher-order terms to achieve the true flexure of the structure under the combined action of loads. It is assumed that the panel structure is exposed to nonuniform temperature field combined with the transversely distributed mechanical load. Additionally, the properties of material constituents are assumed to vary with the nonuniform temperature load and corresponding properties are evaluated considering dependency and independence of temperature. Furthermore, the panel material grading has been obtained mathematically with the help of Voigt’s micromechanical rule together with the power-law distribution. The system of equations is obtained using the variational principle and solved numerically using the finite element steps in association with the direct iterative method. The stability of the present numerical model has been established through the convergence test and compared with the benchmark results to show the validity. Finally, numerical experimentations have been carried out for different parameters and discussed in detail.     

板式塔液体不均匀流动及其改善

在1 2 0 0mm塔盘冷模试验台上 ,在无气相流动情况下 ,进行了单、双溢流液体流动试验 ,测定了塔板板面液体的流动状态。在探讨不均匀流动成因的基础上 ,进行了改善板面不均匀流动的研究。结果表明 :设置不等高入口堰 ,可有效抑制板面两侧弧形区域的液体返混 ,达到整个板面液体均匀流动的效果。工业应用证实它能明显地改善塔板效能。     

地震地层反演在川西致密砂岩气藏描述中的应用

四川盆地川西拗陷陆相致密碎屑岩领域油、气储层具有致密、低孔渗、薄层交互、多层叠置和强非均质性的特点。本文以多井约束地震地层反演技术配套和完善了川西致密非均质气藏描述技术;以高精度三维地震资料为主线,结合钻井、地质、测井、测试等资料,深入研究分析含油、气的地震响应特征,在确定气藏分布范围可形态、反演储集参数、研究沉积相和储层非均质性以及预测高产富集带等方面取得了重大突破。     

应用钢管微型桩对倾斜楼房进行纠偏加固

 一办公楼建于水库岸滩回填地层之上,由于回填处理不当和库区水位季节性变化较大,导致楼房不均匀沉降。利用加固后楼房的反向不均匀沉降,结合钢管微型桩分期和分区施工,成功对楼房进行了纠偏和加固。结合实际工程,介绍使用钢管微型桩对楼房进行基础加固和纠偏的方法,通过观测数据说明钢管微型桩对倾斜楼房进行纠偏加固的效果,期望在处理类似工程问题时起到借鉴作用。     

二维非定常水跃湍流现象的数值模拟

通过求解时均N-S方程及K-ε湍流模型,数值模拟了典型水跃湍流由静止到最终稳定的全过程,采用VOF模型跟踪自由表面的变化.本文给出了水跃现象在不同时刻自由表面的变化情况,主要对水跃过程中自由表面的形状、内部流场结构、速度矢量场及压力场分布进行了分析.结果表明,VOF模型能够有效地描述水跃这类复杂自由表面流道的湍流特性,...