曲柄连杆式飞剪机减速器CAD系统设计

针对曲柄连杆式飞剪机减速器进行了研究.以AutoCAD2002作为开发平台,以VC 6.0为编程环境进行的二次开发,开发出了与AutoCAD自身风格一致的用户接口,人机交互界面友好,操作简单便捷.实现了曲柄连杆式减速器传动机构的常规设计、校核计算、优化设计和参数化绘图一体化.该系统常规设计正确,优化设计结果合理,具有很高的工程使用价值.     

基于运行效率的通行能力计算方法

为了提高交通流模型整体估计精度, 对交通流模型参数估计方法进行了研究.针对密度-速度、密度-流量以及速度-流量模型之间的关联性以及交通流观测数据分布特征对模型估计精度的影响, 提出了联合模型参数估计方法, 并给出了联合模型参数估计优化目标函数的表达形式及约束条件.以Castillo-Benítez和Van Aerde模型为例, 基于北京市二环快速路实测数据对联合模型参数估计方法可行性及参数估计效果进行了验证; 构建了加权判定系数, 并结合平均绝对百分比误差(mean absolute percentage error, MAPE)和平方根误差(root mean squared error, RMSE)评价联合模型估计效果.结果表明, 对Castillo-Benítez模型而言, 由单一模型计算的速度、流量估计MAPE分别是19.8%和18.7%, 基于联合模型计算的速度、流量MAPE分别下降为10.0%和10.0%, 模型总体判决系数由0.913变化为0.910;对Van Aerde模型而言, 由单一模型计算的密度、流量估计MAPE分别为16.4%和16.3%, 基于联合模型计算的密度、流量MAPE分别为14.2%和14.2%, 模型总体判决系数由0.732变为0.749.

     

Influence of bearing damping on instability of asymmetric shafts, part IV: Effects of fluid-film bearings

The influence of fluid-film bearings on the parametric instability of asymmetric shafts is investigated. Since fluid-film bearings may have non-isotropic stiffness and damping, the system equations are time-varying coefficients in a rotating reference frame and the complete solution of transition curves includes coupled modes. Thus, the analytical modal method provided by our previous studies has been modified in this part for the determination of approximate solutions from a truncated Hill's determinant. In numerical examples, a plain cylindrical type and a tilting four-pad type are considered to estimate the effects of bearing parameters concerning static load, oil viscosity, and clearance on unstable regions.     

利用Visual C++开发Pro/ENGINEER三维标准库

从提高产品设计效率和质量出发,探讨了参数化设计功能和Pro/ENGINEER Wildfire环境下三维模型参数化设计的实现策略和途径,分析了基于Pro/TOOLKIT二次开发的三维标准件库参数化设计的过程,并给出了应用实例。     

环口板加固T型方钢管节点在轴压作用下极限承载力的参数分析

为了研究环口板加固对T型方钢管节点在支管承受轴向压力作用下的极限承载力的影响,本文运用前期工作中所采用的有限元模型建立方法,对320个环口板加固T型方钢管节点进行了参数分析。参数包括支管和主管的宽度比β,主管的宽度与厚度比2γ,环口板与主管厚度比τc和环口板与支管宽度比lc/d1。参数分析结果表明:通过对环口板的宽度和厚度进行适当的组合,可以显著提高节点的承载力。然后将有限元模拟得到的极限承载力结果与前期工作中推导出的极限承载力公式的计算结果进行对比,给出了极限承载力计算公式的适用范围。     

Use of Sobol's Quasirandom Sequence Generator for Integration of Modified Uncertainty Importance Measure

Sensitivity analysis of model output is relevant to a number of practices, including verification of models and computer code quality assurance. It deals with the identification of influential model parameters, especially in complex models implemented in computer programs with many uncertain input variables. In a recent article a new method for sensitivity analysis, named HIM* based on a rank transformation of the uncertainty importance measure suggested by Hora and Iman was proved very powerful for performing automated sensitivity analysis of model output, even in presence of model non-monotonicity. The same was not true of other widely used non-parametric techniques such as standardized rank regression coefficients. A drawback of the HIM* method was the large dimension of the stochastic sample needed for its estimation, which made HIM* impracticable for systems with large number of uncertain parameters. In the present note a more effective sampling algorithm, based on Sobol's quasirandom generator is coupled with HIM*, thereby greatly reducing the sample size needed for an effective identification of influential variables. The performances of the new technique are investigated for two different benchmarks.     

Noisy parametric amplifiers in non-equilibrium thermo field dynamics

Single-mode and two-mode parametric amplifiers under the influence of Markovian environments are studied by means of non-equilibrium thermo field dynamics. In the presence of both parametric coupling and system–environment interaction, the dissipative Heisenberg equations of motion are solved for the optical modes of interest. By making use of the solutions, it is examined whether the noisy parametric amplifiers can exhibit the non-classical properties. Furthermore, it is shown that the two-mode parametric amplifier is equivalent to the two single-mode parametric amplifiers with subsequent beam splitting, even if they are influenced by the environments.     

基于SolidWorks的三螺杆泵螺杆参数化建模系统开发

三螺杆泵螺杆是具有特殊摆线齿形的轴类零件,它在各种三维设计软件中的造型比较复杂。根据三螺杆泵主从螺杆摆线齿形方程,利用SolidWorks API二次开发工具,用VBA语言编程,研究<135>型三螺杆泵主从螺杆参数化建模的方法,实现了三螺杆泵主从螺杆的参数化三维建模。     

Thermodynamic analysis and parametric study of an intercooled–reheat closed-cycle gas turbine on the basis of a new isentropic exponent

The thermodynamic analysis and parametric study of an intercooled–reheat closed-cycle gas turbine is presented in this paper, on the basis of a new (harmonic mean) isentropic exponent. An analytical expression is derived for the optimum pressure ratio and maximum non-dimensional net work output. It is found that the optimum pressure ratio and the maximum non-dimensional net work are high when the ratio of extreme temperatures of cycle (i.e. T _max and T _min) and isentropic efficiencies of compressor and turbine (i.e. η_c and η_t) are high. The theoretical results are also compared with the practical conditions of power plant.     

随车起重机伸缩臂截面多目标优化

为了提高某火箭炮弹药装填车随车起重机伸缩臂的结构刚度,减轻结构质量,建立了随车起重机伸缩臂参数化模型,并对伸缩臂在水平受载状态下进行仿真分析。以伸缩臂截面尺寸参数为设计变量,借助最优拉丁超立方试验设计建立样本空间,构造响应面多项式函数近似模型。在此基础上,利用NSGA-Ⅱ型遗传算法对伸缩臂自身重量、挠度进行多目标优化。优化结果表明:伸缩臂质量减轻了24.5%,减重效果明显。文中所采用的将参数化建模、有限元分析和数值寻优相结合的优化方法,可为起重机伸缩臂截面优化提供一定的参考。