基于混沌的全局优化新方法

牛顿优化技术是重要的一维及多维优化迭代技术,其迭代本身对初始点非常敏感,该敏感区是牛顿优化技术所构成的非线性离散动力系统Julia集,提出一种寻找牛顿优化迭代函数的Julia点的求解方法,利用非线性离散动力系统在其Julia集出现混沌分形现象的特点,提出一种基于牛顿优化技术的全局优化新方法,数值试验表明了该方法的有效性和正确性。     

机构综合的牛顿混沌迭代方法研究

工程中的许多问题都可以转化为非线性方程组的求解问题,牛顿迭代法是重要的一维及多维的迭代技术,其迭代本身对初始点非常敏感,该敏感区是牛顿迭代法所构成的非线性离散动力系统Julia集,提出了用排斥二周期点寻找牛顿迭代函数的Julia点的求解方法,利用非线性离散系统在其Juilia集出现混沌分形现象的特点,首次提出了基于混沌的牛顿迭代的非线性方程组求解新方法。对平面曲柄一滑块机构综合进行了研究,算例表明该方法的正确性与有效性。     

样点邻域同构曲面约束的散乱点云法向估计

针对现有点云法向估计算法难以兼顾估计结果的精度与稳健性问题,以局部采样区域同构曲面作为样点邻域点集所反映曲面形状约束,提出一种散乱点云法向估计方法。该方法将目标样点的邻域点集作为局部样本进行曲面重建,获取插值于采样点集并与采样表面拓扑同构的局部网格曲面;对曲面局部区域高斯映射结果进行聚类分析,获取目标样点的各向同性邻域面;基于面片的正则度以及面片至目标样点的测地距离,确定目标样点各向同性邻域面片法向的加权均值,并将所得结果作为目标样点的法向估计结果。试验结果表明,该方法在点云数据信噪比为40 dB的情况下可保证98%以上样点法向估计偏差在以内,可稳健处理含有噪声以及采样不均匀等缺陷的散乱点云法向估计问题,对于含尖锐特征的点云亦能准确估计样点法向,且具有较高的计算效率。     

A robust parametric method for power harmonic estimation based on M-Estimators

Power harmonic estimation is essential for evolving suitable protection and control strategies of power networks. Parametric approaches exhibit super-resolution and have been gradually applied in practice. However, they are susceptible to the presence of noise in the signals. The analysis accuracy will be abruptly reduced and even ineffective under non-Gaussian or impulsive noise environment. In this paper, a novel approach based on M-Estimators for harmonic estimation is proposed to overcome the above shortcomings. The derivation of Gauss–Newton iteration equations of harmonic frequency, amplitude and phase is presented. Further, the ESPRIT algorithm is also employed to acquire the initial values of harmonic frequencies, which avoids the objective function of M-Estimator to be stuck in local minima and improves the convergence rate of optimization. The numerical simulations and experimental results verify the feasibility and effectiveness of the proposed method.     

基于试验数据的魔术轮胎模型参数估计

为了准确估计魔术轮胎模型参数并构建可信的轮胎动力学模型,基于某型轮胎的纵向力及侧向力试验数据,以测试数据和模型拟合数据残差加权平方和最小为目标函数,采用麦夸尔特法（Levenberg-Marquardt）与全局优化法相结合的混合优化算法,分别对8个轮胎纵向力及10个轮胎侧向力模型参数进行估计.拟合优度统计检验结果表明魔术轮胎模型回归效果非常显著,拟合精度较高.纵向力及侧向力模型拟合曲线与试验测点拟合较好,纵向刚度及侧偏刚度测试结果与计算结果的最大相对误差分别只有8.48％和9.96％,具有很好的一致性,验证了参数估计的准确性.     

A robust and efficient method for direct projection on point-sampled surfaces

A novel and robust approach for computing the direct projection onto a point cloud for a given 3D point with associated projection vector is proposed. An energy function is presented to model the active contour, and the curve evolving method is applied to track the projection in certain iterations. In each step of the iteration, the energies of the related points are used to estimate the step length and orientation of the evolution. Then the point’s position is continuously updated and approximates the solution until the given accuracy is reached. The proposed approach directly operates on the point cloud, which is followed by a refining process to correct the results for under-sampled regions. Since the algorithm is carried out on a small point set (i.e., the neighborhood of the test point, generally composed of 30∼60 points) it is not expensive computationally. By numerical experiments, the method has been demonstrated to be more robust and efficient than the existing direct projection approaches on processing discrete point clouds.     

路面病害检测系统中的图像增强技术

为了提高路面病害检测系统的精度和自适应能力,研究了自动路面裂缝图像增强技术。针对图像每个像素建立由邻域一致性模糊熵测度、邻域模糊方差以及全局模糊隶属度组成的模糊特征模式对所有像素进行分类,实现对像素灰度渡越点位置的准确估计;在模糊隶属度函数设计上,利用修改控制顶点和权因子可局部地修改曲线形状的功能,通过非均匀有理B样条函数设计出一种双"S"形模糊隶属度函数作为灰度变换函数。提出的路面裂缝图像增强技术中的灰度变换函数不仅能和渡越点的位置很好地结合,而且其形状调节因子具备良好的灰度集中能力,仅需很少次数迭代增强就能达到突出路面裂纹的效果。实验结果显示,利用提出的图像增强技术可使路面裂缝病害像素正确检测率达到95%,该技术很大程度地提高了路面裂缝自动检测系统的可靠性和检测精度。     

发汗冷却系统的自校正控制

对发汗冷却系统的自校正控制问题进行了讨论,给出了一个基于实际观测的自 校正控制算法。根据单点或多点测温,应用最小二乘及最佳摄动法,确定气动加热面 边界热流密度。由热平衡方程给出输入函数控制律,数值仿真结果显示此方法可以 取得很好的控制效果。     

New decentralized control technique based on substructure and LQG approaches

Decentralized control is more suitable for structural control of large-scale structures. In this paper, a new decentralized control technique is proposed based on the linear quadratic Gaussian (LQG) and substructure approaches. A large-scale structure is divided into a set of smaller substructures. Each substructure is controlled by its own local controller with interaction forces at substructural interfaces, which are considered as “unknown external inputs” to the substructure concerned. An algorithm of recursive least squares estimation for the unknown excitation is proposed. A numerical example of the decentralized control of a tall building is studied to illustrate the new proposed algorithm. Simulation results show that the proposed decentralized control provides satisfactory control performance when comparing with the conventional centralized LQG control algorithm and is viable for the future structural control of large-scale structures.     

平面四杆机构函数综合优化设计

分析了传统的以连杆定长方程残差平方和为目标函数的优化设计方法的不足之处,在此基础上提出了以输出角偏差平方和为目标函数的新方法,给出了输出角以及新目标函数的表达式.