Design of conformal cooling channels for an automotive part

The cooling system plays a crucial role in determining the productivity and quality of an injection molding process. With the current growth of Solid Freeform Fabrication (SFF) techniques, mold designers have been striving for not only improvement in cooling system performance but also for a method to do so automatically. In this paper, a method is proposed for developing a conformal cooling system that facilitates uniform cooling over the entire mold surface with minimum cycle time. Based on the temperature distribution after the filling stage, the mold surface is split into zones which will be cooled by optimized subconformal channels obtained from the optimization process. The optimization process in which the objective function is stated as minimization of the cooling time with boundaries ensuring a realistic design will optimize the cooling system layout in terms of cooling channel size and location. Finally, all subcooling channels are combined to generate the entire conformal cooling system for the injection mold.     

Parallel Distributed Implementation of Truss Optimization on a Local Area Network

A two-level optimization method for the design of complex truss and parallel distributed implementation on a LAN is presented using parallel virtual machine (PVM) for Win 32 as message passing between PCs. The volumes of truss are minimized by decomposing the original optimization problem into a number of bar optimization problems executed concurrently and a coordinate optimization problem, subject to constraints on nodal displacements, and stresses, buckling and crippling of bars, etc. The system sensitivity analysis that derives the partial derivatives of displacements and stresses with respect to areas are also performed in parallel so as to shorten the analysis time. The convergence and the speedup performances as well as parallel computing efficiency of the method are investigated by the optimization examples of a 52-bar planar truss and a 3 126-bar three-diraensional truss. The results show that the ideal speedup is obtained in the cases of 2 PCs for the 3 126-bar space truss optimization, while no speedup is observed for the 52-bar truss. It is concluded that (1) the parallel distributed algorithm proposed is efficient on the PC-based LAN for the coarsegrained large optimization problem; (2) to get a high speedup, the problem granularity should match with the network granularity;and (3) the larger the problem size is, the higher the parallel efficiency is.     

汽车覆盖件冲压方向优化系统设计

通过分析影响汽车覆盖件冲压方向选择的因素,建立了以评价函数法为基础的冲压方向优化模型。利用该模型对冲压件截面形状进行了分析,确定了截面转角的公共可行域,并建立了一组目标函数作为优化对象。在公共可行域内优化各个截面的转角,然后加权平均可得到目标函数的最优值。以典型汽车覆盖件为例,对实现覆盖件冲压方向的优化系统进行了理论验证。     

汽车侧面碰撞乘员约束系统的多目标优化

针对某轿车建立了基于多刚体理论的侧面碰撞乘员约束系统动态仿真模型,并依据试验结果进行了模型的有效性验证。通过对乘员侧面碰撞伤害指标的分析,提出了包含乘员多输出目标值的综合伤害评估值,并应用试验设计方法,以所提出的综合伤害评估值为目标进行了该车的侧面碰撞乘员约束系统多参数优化,给出了符合实际的优化结果。     

Stationary ultracapacitors storage device for improving energy saving and voltage profile of light transportation networks

The installation of stationary ultracapacitor storage devices, as widely recognized, allows the recovery of the braking energy for increasing the energy efficiency as well as a better pantograph voltage profile. In the paper a new methodological mean is proposed for determining the fundamental characteristics of this kind of storage device, characterized by high power density, interfaced with the railroad by a bidirectional dc-dc converter. More specifically, the parameters of the storage system can be determined by employing an optimization technique which in a quite general way is able to take contemporaneously into account several aspects in an integrated manner. Some considerations are performed for properly taking into account the stochastic aspects of the design procedure. Numerical simulations with respect to a case study are presented, pointing out the potentiality of the tailored technique. Experimental results are also reported, with reference to an electromechanical simulator, in order to put in evidence the effectiveness and the actual implementation of the proposed optimization technique.     

基于粒子群优化小波神经网络的行程时间预测

为使道路使用者在出发前获得具有高实时性和可靠性的行程时间预测信息,提高出行效率,需提升高速公路行程时间的预测精度。鉴于此,将生物学中粒子群优化算法（Particle Swarm Optimization Algorithm, PSO）引入小波神经网络（Wavelet Neural Network, WNN）中,构建基于粒子群优化小波神经网络（Particle Swarm Optimization Wavelet Neural Network, PSO-WNN）的高速公路行程时间预测模型。首先将高速公路原始收费数据规整化,截取其中有效字段,获取研究路段一个月的行程时间数据并对其进行数据处理。然后分别基于PSO-WNN模型和WNN模型,利用Matlab进行实验。实验结果显示,PSO-WNN模型预测结果的平均绝对误差、平均相对误差和均方误差较WNN模型分别降低了83.36%, 82.20%和98.15%。PSO-WNN行程时间预测模型不仅预测精度高,而且能较准确地预测出行程时间的走向及波动情况,在收敛速度方面也呈现出一定的优势,具有较好的适应能力。     

多学科设计优化在桁架式Spar平台概念设计中的应用(英文)

在传统的桁架式Spar设计过程中,设计人员通常只选择一个或两个学科作为某个阶段的设计目标,而没有把设计过程作为一个整体进行研究.同时,传统的设计方法没有充分考虑决定Spar性能的多个学科之间的相互影响和耦合作用.因而,传统的设计方法很难获得最优的设计方案.为解决这一问题,该文将多学科设计优化方法引入桁架式Spar的概念设计,以实现真正的设计优化.文中首先介绍了桁架式Spar的传统设计方法以及多学科设计优化的基本理论,讨论了如何将多学科优化技术应用于Spar平台的概念设计.进而提出了一种适用于Spar设计的多学科设计优化方法-基于响应面的协同优化方法,并基于该方法,建立了桁架式Spar的设计优化框架.最后,对今后的研究方向提出了几点建议.     

果蝇算法在基于LSSVM智能水下机器人操纵运动模型辨识中的应用

基于水下机器人的Z型仿真试验,应用支持向量机对水下机器人的操纵运动模型进行辨识,从核函数结构中得到水动力系数,并建立水下机器人的预报模型,引入果蝇算法对惩罚因子C进行寻优,以减少基于经验而选择的参数对辨识精度产生的影响。通过预报与仿真比较,验证了该方法的有效性。     

多种多学科设计优化方法的比较研究

多学科设计优化(Multidisciplinary Design Optimization,MDO)是一种通过充分探索和利用系统间的相互作用的协同机制来设计复杂系统工程和子系统的方法论.随着多学科设计优化方法在船舶与海洋工程中的广泛应用,多学科设计优化方法越来越受到重视,目前已经发展出了多种不同的具体算法.该文的主要目的就是对这些现有的算法开展比较研究,为后续的应用选择奠定基础.论文首先介绍了MDO算法的分类和发展,对各种MDO算法的优缺点进行了比较分析,最后再通过具体算例来显示这些方法的差别.     

连续梁桥0^#块施工支架方案优化设计

文章针对南充嘉陵江特大桥连续梁0#块支架前期设计方案存在的问题,提出了连续梁0#块施工支架优化方案,并通过技术性与经济性对比分析,验证了优化设计方案的合理性。