General triangular midpoint subdivision

In this paper, we introduce triangular subdivision operators which are composed of a refinement operator and several averaging operators, where the refinement operator splits each triangle uniformly into four congruent triangles and in each averaging operation, every vertex will be replaced by a convex combination of itself and its neighboring vertices. These operators form an infinite class of triangular subdivision schemes including Loop's algorithm with a restricted parameter range and the midpoint schemes for triangular meshes. We analyze the smoothness of the resulting subdivision surfaces at their regular and extraordinary points by generalizing an established technique for analyzing midpoint subdivision on quadrilateral meshes. General triangular midpoint subdivision surfaces are smooth at all regular points and they are also smooth at extraordinary points under certain conditions. We show some general triangular subdivision surfaces and compare them with Loop subdivision surfaces.     

Dynamic surface control of a piezoelectric fuel injector during rate shaping

Fuel injection rate shaping is a strategy to improve fuel efficiency and reduce harmful emissions in diesel engines. Due to their fast response, piezoelectric fuel injectors are capable of rate shaping operation. This paper describes a model-based closed-loop controller of injection flow rate for a piezoelectric fuel injector. This within-an-engine-cycle control strategy utilizes a dynamic surface control scheme and shows an injection flow rate tracking capability. Practical issues with LabVIEW FPGA control implementation are also addressed. The performance of the controller is verified with simulation and experimental results at different rail pressures and desired injection rates. The experiments show a maximum error of total fuel per one injection event of 2.5%. A stability analysis is also included.     

基于视觉文化理论的安徽城市形象塑造与传播

一座城市形象的塑造与这座城市的文化有关,当然,也与其一贯表现出现的形象有关。一座城市形象的形成是基于外地人对这座城市的直观上的感受,这就是视觉文化理论的作用。安徽城市形象的塑造基于其视觉文化的形成,如何传播安徽城市形象,以使得安徽在人们眼中拥有较为完美的形象也需要视觉文化理论的支持。     

Controller design for nonlinear systems using the Contoured Robust Controller Bode plot

In this paper, we develop the Contoured Robust Controller Bode (CRCBode) plot and demonstrate its use in the design of robust controllers for nonlinear single‐input single‐output (SISO) systems. The CRCBode plot shows contours (level sets) of a robust performance quantity on the Bode magnitude and phase plots of the controller. An iterative frequency domain loop‐shaping design approach is employed to eliminate all intersections of the controller frequency response with certain ‘forbidden regions,’ indicating that a standard SISO robust stability and performance criterion is satisfied. Nonlinearities are accounted for by avoiding the maximum forbidden regions over a structured uncertainty set consisting of linearizations of the system dynamics about several operating points. We demonstrate this technique by designing and experimentally verifying a flow‐rate controller for a butterfly‐valve based liquid cooling system, which is robust to valve nonlinearities and flow disturbances. Finally, we compare this compensator with one generated using an automated H _∞ synthesis algorithm and discuss the advantages of the CRCBode approach. Copyright © 2013 John Wiley & Sons, Ltd.     

基于Pscad/Emtdc电网合环仿真的研究

本文以抚州金巢变电站10kV配电网合环为例,基于电磁暂态仿真软件PSCAD/EMTDC准确地搭建了系统仿真模型,以解决配电网合环操作过程中可能出现的涌流现象引起保护误动作。提出在合环点两侧相位差较小时候合环,或者通过调整变压器分接头以减小合环点两端母线电压差,从而减小合环电流。     

Matlab中的代数环问题及其消除方法

本文以免疫PID的SimuLink模型及其S函数为例引出代数环问题,分析了代数环的基本概念,指出了代数环对控制系统仿真的巨大危害,最后结合实际提出了几种消除代数环的方法。结果表明,代数环消除后提高了系统的仿真精度和运行速度。     

鱼雷静不稳定状态下纵向三回路过载控制与仿真研究

静不稳定控制技术作为现代航空航天、水中兵器主动控制技术,在近些年逐渐成为研究热点。本文针对某静不稳定鱼雷,建立了纵向运动模型,运用最优控制理论设计了俯仰通道三回路过载控制系统,最后对设计出的控制器进行了特征点控制系统仿真。结果说明,三回路过载控制方法能较好地控制静不稳定鱼雷。     

基于Loop细分算法的人体模型网格平滑

网格平滑是实现三维模型离散造型的主要方法。为了实现数字人体几何模型的光顺效果,本文提出一种基于Loop细分算法的三维人体模型的网格平滑方法。细分曲面是用低分辨率的控制网格和定义在控制网格上的一种细分规则来表示曲面的,它能有效改善三维人体几何模型的表面不光滑以及分辨率低的缺点。实验证明,该方法对基于参数化建模方法的、多曲率网格人体模型取得了很好的效果,实现简单高效,特征保持效果也很好。     

渐开线零齿差机构啮合原理与强度条件

零齿差机构的突出问题是齿轮的干涉与强度。在导出避免干涉的条件后，建立新的强度公式，给出各项检验指标，并提出切齿过程中保证精度的具体措施。     

直角密集台阶轧齐曲线

本文在分析具有密集性质的直角台阶轧齐问题中，提出里台阶轧齐曲线相对独立，外台阶轧齐曲线受里台阶影响，并形成某种叠加的基本设想。逐个分析了密集台阶存在的四种状态，推导出各种状态下每个台阶的轧齐曲线方程，并给出了各种状态的判别式及各方程的区间。文章最后以简图方式汇总了各种状态，并用例题归纳了计算步骤。