基于无网格局部Petrov-Galekin法的板结构拓扑优化

为将无网格法的优势集成到结构拓扑优化中,基于无网格局部Petrov-Galerkin(Meshless Local Petrov-Galerkin,MLPG)法进行板结构的拓扑优化.基于带惩罚的各向同性固体微结构(Solid Isotropic Microstructure with Penalization,SIMP...     

T-S模糊离散多时滞系统的H∞控制

提出了一种新型非二次型Lyapunov函数, 在非并行分布补偿控制策略框架下, 研究了一类基于T-S模糊模型的离散多时滞系统的H∞控制. 通过引入一个矩阵变换, 所得控制律均以线性矩阵不等式的形式给出. 现有的并行分布补偿控制律可视作该新方法在某些条件下的特例. 仿真算例显示, 该函数方法保守性较低, 系统控制性能良好.     

Topology optimization of transient problem with maximum dynamic response constraint using SOAR scheme

Frontiers of Mechanical Engineering - This paper proposes a novel method for the continuum topology optimization of transient vibration problem with maximum dynamic response constraint. An...     

三维线弹性连续体的结构拓扑优化设计

研究了基于水平集模型和SIMP方法的三维线弹性结构的拓扑优化方法，优化模型的目标是结构的柔度最小。引入水平集模型隐含描述具有复杂拓扑关系的三维线弹性结构的几何边界，以材料域的形状为变量进行灵敏度分析，构造水平集方程的速度函数，通过几何边界的演化获得结构的最优形状和拓扑。同时研究了基于SIMP方法的三维连续体结构的拓扑优化设计。对基于水平集模型和SIMP的拓扑优化方法的数值算例进行比较，结果表明，基于水平集的三维结构拓扑优化具有光滑的几何边界，数值算法稳定。     

Isogeometric topology optimization based on energy penalization for symmetric structure

We present an energy penalization method for isogeometric topology optimization using moving morphable components (ITO–MMC), propose an ITO–MMC with an additional bilateral or periodic symmetric constraint for symmetric structures, and then extend the proposed energy penalization method to an ITO–MMC with a symmetric constraint. The energy penalization method can solve the problems of numerical instability and convergence for the ITO–MMC and the ITO–MMC subjected to the structural symmetric constraint with asymmetric loads. Topology optimization problems of asymmetric, bilateral symmetric, and periodic symmetric structures are discussed to validate the effectiveness of the proposed energy penalization approach. Compared with the conventional ITO–MMC, the energy penalization method for the ITO–MMC can improve the convergence rate from 18.6% to 44.5% for the optimization of the asymmetric structure. For the ITO–MMC under a bilateral symmetric constraint, the proposed method can reduce the objective value by 5.6% and obtain a final optimized topology that has a clear boundary with decreased iterations. For the ITO–MMC under a periodic symmetric constraint, the proposed energy penalization method can dramatically reduce the number of iterations and obtain a speedup of more than 2.     

Multiphase topology optimization with a single variable using the phase-field design method

In this study, a multimaterial topology optimization method using a single variable is proposed by combining the solid isotropic material with penalization method and the reaction-diffusion equation. Unlike ordinary multimaterial optimization, which requires several variables depending on the number of material types, this method intends to represent various materials as one variable. The proposed method combines two special functions in the sensitivity analysis of the objective function to converge the design variable into prespecified density values defined for each of the multimaterials. The composition constraint based on a normal distribution function is also introduced to estimate the distribution of each target density value in a single variable. It enables density exchange between multiple materials by increasing or decreasing the amount of a specific material. The proposed method is applied to structural and electromagnetic problems to verify its effectiveness, and its usefulness is also confirmed from the viewpoint of cost and computation time.     

几类反射随机微分方程强解的数值仿真

反射随机微分方程在排队论、金融保险、存储系统建模、计算机网络研究中均具有广泛应用。文中回顾了反射随机微分方程的形式和方程解的定义,将无反射随机微分方程数值思想引用到反射情形,研究基于反射随机微分方程的Euler-Maruyama算法、Euler-Peano算法和惩罚数值算法。并以Ornstein-Uhlenbeck过程和反射Ornstein-Uhlenbeck过程为实例,对上述算法进行了仿真实验和比较。结果表明,在期权定价、利率期限结构、金融风险计算与受控金融市场建模等实际应用中具有良好的应用前景。     

采用动态风险管理方法的水电站短期优化调度

市场环境下,径流的随机性、发电量的不确定性使得水电站愈加关注其面临的收益风险,如何在调度决策中进行风险管理是其需要解决的重要问题。提出以随机场景分析方法表示电价的波动特征,结合风险惩罚模式和风险约束模式,建立基于动态风险管理方法的水电站短期优化调度模型,以改进快速进化算法(improved fast evolutionary algorithm,IFEP)与遗传算法(genetic algorithm,GA)相结合的IFEP-GA混合优化算法作为模型的求解方法,进化策略结合了高斯变异和柯西变异的特点,约束的处理结合了惩罚机制与修复机制,这使得算法具有良好的寻优能力和收敛特性。不同风险管理模式对水电站优化运行影响的分析结果表明,动态风险管理策略能够更好地平衡期望收益、风险及末期库容约束的违反,减小风险的同时获得了更高的期望收益,为水电站依据自身风险接受程度灵活安排调度决策提供理论依据。     

一类控制受约束非线性系统的基于单网络贪婪迭代DHP算法的近似最优镇定

提出一种贪婪迭代DHP (Dual heuristic programming)算法, 解决了一类控制受约束非线性系统的近似最优镇定问题. 针对系统的控制约束, 首先引入一个非二次泛函把约束问题转换为无约束问题, 然后基于协状态函数提出一种贪婪迭代DHP算法以求解系统的HJB (Hamilton-Jacobi-Bellman)方程. 在算法的每个迭代步, 利用一个神经网络来近似系统的协状态函数, 而后根据协状态函数直接计算系统的最优控制策略, 从而消除了常规近似动态规划方法中的控制网络. 最后通过两个仿真例子证明了本文提出的最优控制方案的有效性和可行性.