旋转圆锥网格及其在玻璃/钢结构中的应用

圆锥网格是计算机辅助建筑设计中一类新的平面四边形网格,具有良好的等距性质,非常适用于玻璃/钢结构,而旋转曲面是建筑设计中的常用形状.通过引入旋转圆锥网格的概念,并利用圆锥网格的定义,给出了构造旋转圆锥网格的简单方法.证明了只在旋转曲面r(u,v)=(f(u)cosv,f(u)sinv,g(u))的v参数方向进行均匀分割,而在U参数方向进行任意分割,则所产生的平面四边形网格为圆锥网格;并研究了旋转曲面为圆锥曲面和圆柱曲面的特殊情况;最后给出了基于旋转圆锥网格的玻璃结构造型实例.该方法简单易行,对计算机辅助建筑设计中的玻璃/钢结构造型有一定的实际应用价值.     

不规则网格上的曲面设计方法

提出一种在不规则网格上构造曲面的方法.其基本思想是,通过均匀双三次B样条基函数的分解和子基函数的分类,将B样条曲面方法推广到任意四边形网格.给定一个任意四边形控制网格,首先对每个控制点构造一个基函数;所有控制点加权组合形成整体曲面.构造的曲面是分片双三次有理参数多项式曲面.此方法可以看成是均匀B样条曲面构造方法的扩展,如果控制网格是规则四边形网格,那么构造得到的曲面与均匀双三次B样条曲面是一致的.最后,实例证明此方法能够有效地构造曲面.     

模拟退火遗传算法的轮廓线拼接研究

基于断层数据的三维重构是三维数据场可视化技术的主要研究内容,重构物体的三维模型也是分析、仿真的前提.应用模拟退火遗传算法设计和实现了三维物体表面重建算法.通过在遗传算法中融人退火处理操作,提高了种群的多样性,避免了遗传算法中存在的早熟收敛问题,有效地增强了算法的全局寻优能力.此外,提出了一种基于边的最小交叉多边形算法,提高了交叉操作效率.根据轮廓线拼接问题的特点,设计了针对性强的交叉、变异操作.实验结果表明,算法有效地提高了传统的全局法轮廓线拼接算法的效率.     

PNG复杂曲面纹理映射的仿真方法

随着PNG图片越来越广泛的应用,所以研究复杂曲面纹理映射的方法有着重要的意义.为了在保持低存储量,小计算量的同时,针对PNG图片的复杂曲面自动纹理映射的变形,根据纹理扰动的缺点.提出了一种改进的复杂曲面纹理映射的方法,通过利用解二次椭圆偏微分方程,来得到任意曲面到平面的共形映射.方法不但可以自动分配纹理坐标到复杂的没有起伏的曲面,而且可以有效地克服复杂曲面的自动纹理映射的变形.避免纹理扰动,很好地解决了纹理的自动映射.     

柔性变形机翼后缘拓扑优化设计

为了实现机翼表面的自适应变形和结构轻量化,将柔件机构引入到机翼后缘形状变化结构设计中.应用连续体拓扑优化技术,以实际位移与目标位移之间的偏差为目标函数,材料用量为约束,建立SIMP(solid isotropic material with penalization)密度刚度插值模型.采用Matlab编程对柔性机构进行了优化设计,并对不同参数下的优化结果进行了讨论,最后进行机构的仿真分析.研究结果显示该柔性机构能够实现预期的形状变化,证明了方法的正确性,为柔性机翼设计提供理论基础.     

Combined analytical solution of overland flow and sediment transport

With reference to the kinematic wave theory coupled with the hypothesis of constant linear velocity for the rating curve, rising limb analytical solutions have been calculated for overland flow, over an Hortonian-infiltrating surface, and sediment discharge. These analytical solutions are certainly easier to use than the numerical integration of the basic equations and they may be used to obtain an initial evaluation of the parameters of more complex models generally devised for complicated cases.Notation a exponent of the Horton law [T^–1] - b exponent of the rill erosion equation - B inter-rill erosion coefficient [ML^–m–2T ^m–1] - c sediment concentration [ML^–3] - c _o reference sediment concentration [ML^–3] - E _I inter-rill erosion [ML^–2T^–1] - E _R rill erosion [ML^–2T^–1] - f _c final infiltration rate of the soil [LT^–1] - f _o initial infiltration rate of the soil [LT^–1] - h flow depth [L] - h _o reference flow depth [L] - i infiltration rate [LT^–1] - k rill erosion coefficient [ML^–1–b T^–1] - K integration constant - L() Laplace transformation - m exponent of the inter-rill erosion equation - n Manning's coefficient [L^–1/3T] - p rainfall intensity [LT^–1] - q water discharge per unit width [L²T^–1] - q _s sediment discharge per unit width [ML^–1T^–1] - t time [T] - t _p ponding time [T] - x distance along the flow direction [L] Greek Letters coefficient of the stage-discharge equation [L^2–T^–1] - exponent of the stage-discharge equation - rill erosion coefficient [L^–1]     

应用NURBS曲面磨光多面体

本文应用ＮＵＲＢＳ曲面磨光多面体,产生了处处Ｃ′连续的过渡曲面．多面体的磨光分为边的磨光和顶点的磨光两种情形,边的磨光相对较容易,而顶点的磨光则很困难．本文所采用的应用ＮＵＲＢＳ曲面磨光多面体的顶点和边的方法,不仅可以统一实现二者的磨光操作,而且方法简单且统一,产生了Ｃ′连续的过渡面．较之以前的方法,首先,利用ＮＵＲＢＳ曲面可以精确地描述对边磨光所用的柱面（等半径或非等半径）,其次,在对顶点的磨光中,同以往的方法不同,将与该顶点相邻的边的过渡曲面相互分离,并首次引入了“补面”的概念,使得对该点所产生的过渡曲面处处Ｃ′连续．本算法首先构造用以磨光多面体顶点和边的ＮＵＲＢＳ曲面的边界曲线网络图产生边界曲线的控制点及其权值（ＮＵＲＢＳ表示）,然后依据连续性准则,产生ＮＵＲＢＳ曲面的控制信息．     

响应面法微波降解EGCG制备EGC研究

目的 为探究微波降解EGCG方法制备EGC的效果,以EGC得率最大化为目标,探究微波降解的最佳工艺参数,并建立反映各参数间关系的二次多元方程模型。方法 本研究采用EGCG溶液为原料,运用微波加热降解EGCG制备EGC,通过梯度设置EGCG浓度、微波时长、微波强度三个工艺参数,进行单因素实验、响应面分析及最佳工艺组合验证实验,优化确定EGCG微波降解制备EGC的最佳工艺参数。结果 综合单因素实验及响应面分析,得到的最佳微波降解参数为：EGCG浓度5mg/ml、微波时长3.5min、微波强度为400W,且利用响应面法建立了EGC得率(Y)与EGCG浓度(A)、微波时长(B)、微波强度(C)的二次多元方程模型：Y=59.52+8.38*A+5.38*B+3.53*C-4.04*AB+6.92*AC-9.19*BC-9.99A2⁺0.0786*B2^-15.36*C2^,模型中,EGC得率最高可达62.08%。对最佳微波降解工艺参数进行验证实验,EGC得率为63.40%,与模型预测值接近。结论 运用微波降解EGCG制备EGC具有操作简单,可行性高的优势,且EGC得率稳定性高。     

Surface Control and Electrical Tuning of MXene Electrode for Flexible Self-Powered Human–Machine Interaction

MXene materials emerge as promising candidates for energy harvesting and storage application. In this study, the effect of the surface chemistry on the work function of MXenes, which determines the performance of MXene-based triboelectric nanogenerator (TENG), is elucidated. First-principles calculations reveal that the surface functional group greatly influences MXene work function:  OH termination reduces the work function with respect to that of bare surface, while  F and  Cl increase it. Then, work functions are experimentally determined by Kelvin probe force microscopy. The MXene prepared by gentle etching at 40 °C for 48 h (GE_40/48) has the largest work function. Furthermore, an electron-cloud potential-well model is established to explain the mechanism of electron emission-dominated charge transfer and assemble a triboelectric device to verify experimentally its conclusions. It is found that GE_40/48 has the best performance with a 281 V open-circuit voltage, 9.7 µA short-current current, and storing 1.019 µC of charge, which is consistent with the model. Last, a patterned TENG is demonstrated for self-powered human–machine interaction application. This finding enhances the understanding of the inherent mechanism between the surface structure and the output performance of MXene-based TENG, which can be applied to other TENG based on 2D materials.