基于Plant Simulation的船厂平直车间作业仿真与优化

船体分段的制造在整个船舶生产过程中占据了大量时间,因此,缩短分段制造时间是缩短船舶建造周期、降低建造成本、提高船厂生产效率的关键所在。以船厂平直车间为研究对象、以缩短车间生产平面分段的最大流程时间为目标,使用Plant Simulation对平面分段的生产制造流程进行模拟仿真,并基于仿真结果使用内置遗传算法功能模块对分段生产顺序进行优化处理,以达到缩短最大流程时间的目的,对分段车间的生产排程具有实际意义。     

Modal split in offshore supply network under the objective of emissions minimization

We study modal split under the objective of emissions minimization in the transportation of cargo from centralized vendors in the oil and gas industry to decentralized supply bases on the Norwegian coast. The supply network includes direct road transport and a sea route along the coast. To gain insight into modal split decisions between road and sea transport from the shipper’s perspective multi-period mixed integer optimization models are formulated. Particularly the models give possibilities to examine how weekly demand patterns at supply bases, cargo commitments to sea transport, storage possibilities at supply bases, and shipper’s responsibility for a certain share of vessel capacity may effect the emissions and the modal split. Experiments on real data from an oil and gas company operating offshore show that the size of the share of vessel capacity and the possibility for storage at supply bases are the major determinants for a larger shift to environmentally friendly sea transport. The models can be used as means for making decisions regarding how a shipper can commit to sea transport to achieve less emissions.     

CFD技术在发动机冷却水套优化设计中的应用

为了分析冷却水套能否满足发动机的散热需求,文章通过CFD软件AVL-Fire对其进行了三维数值模拟,得到了水套流场的对流换热系数,其中缸盖鼻梁区的换热系数过低,需要对水套进行优化设计。对方案优化后再次进行了分析,结果表明,优化后的水套在热负荷较大的区域的对流换热系数均超过推荐值,能够满足散热要求。     

后地板安全带固定点结构优化设计

针对后地板安全带固定点的3种结构形式,对后地板安全带固定点相关法规进行了介绍,并对后排安全带固定点的强度进行了分析。通过分析某车型后地板安全带固定点强度失效原因,对其后地板安全带固定点结构和焊点进行了优化,优化后的结构在模具冲压和车身焊接中均未出现问题,满足了静拉试验相关法规要求。     

面向船厂管子制造流程的仿真优化

管子生产是造船企业生产组织中的重要的加工环节,其生产计划的制定具有计算复杂性和多约束性的特点。结合仿真与优化算法,首先对船舶管子制造流程详细分析,构建管子生产流水线,并应用Plant-Simulation软件建立仿真模型,对船舶管子生产流水线的瓶颈进行分析,最后应用遗传算法实现生产计划的优化。利用国内某造船厂实际数据进行验证,结果表明该方法能够有效缩短工期。     

重型商用汽车车架轻量化设计

车架是汽车的主要承载构件,其功用是承受来自车内外的各种载荷,连接汽车的各大总成及各种车用设备,结构型式主要取决于汽车的总布置要求。深入研究车架的承载特性是车架结构设计改进和优化的基础,也是保证整车性能的关键。本文以某载货车车架为研究对象,建立了车架有限元分析模型;通过该车架模态仿真,验证了有限元模型的正确性;根据载货车的承载特点和行驶工况,对该车架在满载弯曲工况和满载扭转工况的静态应力分析,考察某载货车车架在典型工况下的应力分布,以此评价车架设计的合理性。在以上分析的基础上,本文对车架的连接横梁进行了结构优化,并对改进方案进行了有限元分析,通过与原结构的动态性能对比分析,确定了结构改进的可行性。     

Optimal locations of electric public charging stations using real world vehicle travel patterns

We propose an optimization model based on vehicle travel patterns to capture public charging demand and select the locations of public charging stations to maximize the amount of vehicle-miles-traveled (VMT) being electrified. The formulated model is applied to Beijing, China as a case study using vehicle trajectory data of 11,880 taxis over a period of three weeks. The mathematical problem is formulated in GAMS modeling environment and Cplex optimizer is used to find the optimal solutions. Formulating mathematical model properly, input data transformation, and Cplex option adjustment are considered for accommodating large-scale data. We show that, compared to the 40 existing public charging stations, the 40 optimal ones selected by the model can increase electrified fleet VMT by 59% and 88% for slow and fast charging, respectively. Charging demand for the taxi fleet concentrates in the inner city. When the total number of charging stations increase, the locations of the optimal stations expand outward from the inner city. While more charging stations increase the electrified fleet VMT, the marginal gain diminishes quickly regardless of charging speed.     

Modeling dry-port-based freight distribution planning

In this paper we review the dry port concept and its outfalls in terms of optimal design and management of freight distribution. Some optimization challenges arising from the presence of dry ports in intermodal freight transport systems are presented and discussed. Then we consider the tactical planning problem of defining the optimal routes and schedules for the fleet of vehicles providing transportation services between the terminals of a dry-port-based intermodal system. An original service network design model based on a mixed integer programming mathematical formulation is proposed to solve the considered problem. An experimental framework built upon realistic instances inspired by regional cases is described and the computational results of the model are presented and discussed.     

Area-wide urban traffic control: A Bee Colony Optimization approach

The paper describes a new method of optimizing traffic signal settings. The area-wide urban traffic control system developed in the paper is based on the Bee Colony Optimization (BCO) technique. The BCO method is based on the principles of the collective intelligence applied by the honeybees during the nectar collecting process. The optimal (or near-optimal) values of cycle length, offsets, and splits are discovered by minimizing the total travel time of all network users travelling through signalized intersections. The set of numerical experiments is performed on well-known traffic benchmark network. The results obtained by the BCO approach are compared with the results found by Simulated Annealing (SA). It has been shown that the suggested BCO approach outperformed the SA.