舰船主尺度论证中的多目标综合评估

舰船主尺度是舰船总体设计中最重要的问题之一,直接影响舰综合航行性能的优劣。为寻求性能综合较优,避免单一性能最优的局面,提出一种多目标综合评估模型,并将其应用于某舰主尺度论证中,首先以满足布置、重量等因素为前提提出多种主尺度方案,再以舰的稳性、快速性、耐波性为目标,根据设计需求分别构造目标函数以及将多目标问题转化为单目标问题的决策函数,通过分析评估优选出3种性能综合较优的方案,使得优化结果更合理有效。     

基于ANSYS有限元分析的高桩码头施工期气温控制研究*

提出从面板角点位移、上部结构受力和基桩受弯等方面实施多目标控制设计思想,并通过ANSYS有限元建模分析,详细地研究了码头面板无温差和有温差两种工况下,高桩码头结构在不同施工期气温条件下的变形和受力变化规律.由此确定施工期气温控制为:面板无温差时,施工期气温控制在11.1℃以上,能够确保角点纵向位移满足规范要求;面板有温差时,则施工期气温需高于21.4℃才能满足要求.     

Motorcycle suspension design using matrix inequalities and passivity constraints

This paper presents a design methodology for the suspension system of a novel aerodynamically efficient motorcycle. Since the machine’s layout and the rider’s seating position are unconventional, several aspects of the machine design, including the suspension, must be reviewed afresh. The design process is based on matrix inequalities that are used to optimise a road-grip objective function – others could be used equally well. The design problem is cast as the minimisation of an H ₂ cost with passivity constraints imposed on the suspension transference. The resulting bilinear matrix inequality problem is solved using a locally optimal iterative algorithm. The matrix inequality-type characterisation of positive real functions permits the optimisation of the suspension system over an entire class of passive admittances. Torsional springs, dampers and inerters are then used to construct networks corresponding to the optimal (positive real) admittances. Networks of first, second, third and fourth orders are considered, and an argument based on the compromise between complexity and improved grip is made for the most suitable suspension configuration. Finally, the effects of improved road grip on the stability of the vehicle’s lateral dynamics are analysed.     

Vehicle dynamics control of an electric-all-wheel-drive hybrid electric vehicle using tyre force optimisation and allocation

ABSTRACT

Hybrid Electric Vehicles (HEV) offer improved fuel efficiency compared to conventional vehicles at the expense of adding complexity and at times, reduced total power. As a result, HEV generally lack the dynamic performance that customers enjoy. To address this issue, the paper presents a HEV with electric All-Wheel-Drive capabilities via the use of torque vectoring electric rear axle drive (TVeRAD) to power the rear axle. The addition of TVeRAD to a front wheel drive HEV improves the total power output. To improve the handling characteristics of the vehicle, the TVeRAD provides torque vectoring at the rear axle. A bond graph model of the drivetrain is developed and used in co-simulation with CarSim. The paper proposes a control system which utilises control allocation to optimise tyre forces. The proposed control system is tested in the simulation environment with a high fidelity CarSim vehicle model. Simulation results show the control system is able to maximise vehicle longitudinal performance while avoiding tyre saturation on low mu surfaces. More importantly, the control system is able to track the desired yaw moment request on a high speed double lane change manoeuvre through the use of the TVeRAD to improve the handling characteristic of the vehicle.     

Hierarchical optimisation of the design parameters of a vehicle suspension system

This paper presents a design methodology for the mechanical systems entitled First Design. It is based on a hierarchical organisation of the design, taking into account the notion of robustness at an early phase of the project. The aim is to improve the quality of the system in order to make it robust, less sensitive to the variability of the external parameters and design parameters. We distinguish two main stages of the design cycle: one concerning functional parameters and another concerning physical parameters. The methodology is based on simplified models, on sensitivity analysis and on robust multi-objective optimisation. As an example, the methodology will be applied to the optimisation of vehicle suspension system design parameters. For each stage of the hierarchical design, adapted simplified models, sensitivity analyses and optimisation processes will be studied and applied to our vehicle suspension system.     

社区儿童接送服务车辆的线路优化

以社区儿童接送服务车辆的路线优化问题为研究对象,建立了多目标非线性整数规划模型,其中目标函数包括车辆数最少、车辆行驶的时间最短、所有乘客总旅行时间最短、各辆车的负荷均衡、各辆车的运行时间均衡5个目标.这5个目标分为4个优先级.提出了解决这类问题的新的启发式优化算法.该算法从构造最小生成树开始,找出基本线路;然后通过选择可调单元调整线路得到优化的线路.提出了线路确定后,乘客要求调整线路时应遵循的原则.     

车用替代燃料多目标优化研究

建立了基于生命周期影响评价的车用替代燃料多目标优化模型,以车用替代燃料生命周期影响总水平值为优化目标,并以木薯乙醇为例,对车用替代燃料进行了多目标优化。结果表明,多目标优化后木薯乙醇生命周期影响总水平值降低44.7%,建议木薯乙醇在汽油中的混合比例为95%,在乙醇生产过程中使用天然气燃料。     

Bridging the gap between multi-objective optimization and spatial planning: a new post-processing methodology capturing the optimum allocation of land uses against established transportation infrastructure

The optimal allocation of multiple land uses constitutes a complex multi-objective optimization problem with unknown feasible objective space and optimal planning alternatives. Despite the effectiveness of evolutionary algorithms to capture the underlying Pareto set of optimum maps, land use planners are bound to pursue the best possible spatial allocation of each use within an enormous population of non-dominated solutions. This article presents a novel post-processing methodology enhancing the comparative evaluation of alternative planning approaches without making any assumptions about the (relative) importance of each objective function. The proposed consolidated post-processing module is applied in a land use planning paradigm, revealing: (a) the existence of substantial planning guidelines whose validity is not affected by the relative significance of each criterion and (b) the variable planning component emerging from the (varying) relative importance of objective functions. Such planning feedback could not be extracted by the exhaustive review of non-dominated maps.     

基于多目标粒子群优化算法的某轻型商用车操纵稳定性优化研究

针对某轻型商用车稳态回转时侧倾度偏大的问题对其悬架进行优化改进。基于ADAMS/car搭建整车多体动力学模型,通过前悬架反向平行轮跳试验、后悬架理论计算验证了悬架仿真模型的准确性。进行整车稳态回转工况和转向盘中间位置转向工况仿真分析,结果表明,车身侧倾度偏高。为实现操纵稳定性优化分析的流程自动化,提出了基于modeFRONTIER的联合仿真方法。以悬架设计参数为优化变量,以汽车的侧倾度与横摆角速度响应滞后时间为优化目标,采用拉丁超立方试验设计方法拟合得到混合代理模型,并结合多目标粒子群优化算法对悬架系统进行多目标优化,获得了悬架系统优化方案。优化结果显示,在不影响平顺性的前提下,汽车车身侧倾度降低了13.93%,横摆角速度响应滞后时间降低了2.75%,整车操纵稳定性得到了提升。