基于多智能体系统的海工装备项目物资仓储管控研究

海洋工程装备项目物资仓储管控具有物资种类繁多、仓储点众多、仓储环境复杂、物资调度任务交错进行等特点。为提高海洋工程装备项目的物资仓储管控效率,减少手工操作工作量,本文分析了仓储活动流程,构建了基于MAS （Multi-agent System,多智能体系统）的海工装备项目物资仓储管控系统框架,并进一步针对库位分配问题提出了具体的协商模型和决策算法,最终采用B/S架构开发了基于MAS的海工装备项目物资仓储管控系统原型。实例验证表明,应用多智能体技术可有效辅助海工装备企业进行智能化物资仓储管控。     

Simulation optimization of the berth allocation in a container terminal with flexible vessel priority management

ABSTRACT

Solving the berth allocation problem (BAP) in ports is not trivial where the berth resources are limited and various sizes of vessels arrive with dramatically dissimilar loads. Especially in real scenarios, arriving vessels are accepted for a berth with the first come first served (FCFS) priority rule. This study proposes a decision support system coupled with a simulation optimization module based on the swarm-based Artificial Bee Colony optimization algorithm for solving the BAP. The proposed methodology was implemented for the Izmir port in Turkey. To investigate the influences of the vessel priorities on the BAP, four different experimental scenarios based on the single (SQM) and multiple queue models (MQM) were coupled with FCFS and proposed hybrid queue priority (HQP) rule. The results indicated that SQM scenarios were superior to MQM scenarios in a manner of minimizing the average vessel waiting times and the implementation of a dynamic berth allocation strategy for the MQM significantly decreases the vessel waiting times. Results of the SQM also imply that utilization of the HQP approach further minimizes the average vessel waiting times and increases the berth utilization and port throughput without yielding excessive waiting times for the larger vessels compared with the FCFS priority rule.     

公路客运枢纽的班线组织与配置方法初探

针对公路客运枢纽班线配置问题，对班线组织和配置方法进行研究。在考虑公路客运枢纽布局的基础上，探讨了客运班线的组织和配置原则，提出班线组织主要是协调集约化和分散性两种需求。在总体思路的指导下，宏观配置方法结合场站体系和功能定位，提出了各类型场站班线配置策略；以宏观配置策略为指引，微观配置方法通过建立分区客流预测模型，依据各交通小区到各目标客运站的出行时间和最短路原则，确定各客运站对该类班线的市场划分情况，将该类班线的运力分配到各个客运站，使得总出行成本最小。     

Household type and structure, time-use pattern, and trip-chaining behavior

In order to examine time allocation patterns within household-level trip-chaining, simultaneous doubly-censored Tobit models are applied to model time-use behavior within the context of household activity participation. Using the entire sample and a sub-sample of worker households from Tucson’s Household Travel Survey, two sets of models are developed to better understand the phenomena of trip-chaining behavior among five types of households: single non-worker households, single worker households, couple non-worker households, couple one-worker households, and couple two-worker households. Durations of out-of-home subsistence, maintenance, and discretionary activities within trip chains are examined. Factors found to be associated with trip-chaining behavior include intra-household interactions with the household types and their structure and household head attributes.     

Centralized resource allocation with emission resistance in a two-stage production system: Evidence from a Taiwan’s container shipping company

This paper proposes a centralized network data envelopment analysis model that combines the centralized data envelopment analysis model and network data envelopment analysis to allocate resources among sub-units. In the proposed model, this paper also considers the situations in which undesirable outputs are jointly produced with desirable outputs, the reduction of undesirable outputs is associated with the reduction of energy inputs, and some inputs are dedicated to the specific sub-unit while some inputs are shared among sub-units. To comprehensively investigate this issue, two cases are discussed. One case explores the situation in which common inputs are shared among the first process of sub-units, while the other case explores the situation in which common inputs are also shared among two processes of sub-units. The proposed model is illustrated in an empirical example of 14 Asian shipping routes operated by a Taiwanese container shipping company. In order to avoid organizational resistance, minor and major adjustment policies are demonstrated. The minor adjustment policy transfers inputs among routes but maintains the original levels of input resources, whereas the major adjustment policy reduces the total amount of input resources. The results provide valuable information for the centralized decision-maker on how to reallocate resources among the sub-units.     

Scheduling lane conversions for bus use on city-wide scales and in time-varying congested traffic

The paper explores what can occur when select street lanes throughout a city are periodically reserved for buses. Simulations of an idealized city were performed to that end. The city’s time-varying travel demand was studied parametrically. In all cases, queues formed throughout the city during a rush, and dissipated during the off-peak period that followed. Bus lanes were activated all at once across the city, and were eventually deactivated in like fashion. Activation and deactivation schedules varied parametrically as well. Schedules that roughly balanced the trip-time savings to bus riders against the added delays to car travelers were thus identified.Findings reveal why activating conversions near the start of a rush can degrade travel, both by car and by bus. Balance was struck by instead activating lane conversions nearer the end of the rush, when vehicle accumulation in the city was at or near its maximum. Most of the time savings to bus riders accrued after the conversions had been left in place for only 30 min. Leaving them for longer durations often brought modest additional savings to bus travelers. Yet, the added delays to cars often grew large as a result.These findings held even when buses garnered high ridership shares. This was the case when lane conversions gradually induced new bus trips among residents who formerly did not travel. It was also true when high ridership was a pre-existing feature of the city. Activating conversions a bit earlier in a rush was found to make sense only if commuters shifted from cars to buses in very large numbers. Findings also unveiled how to fine-tune activation and deactivation schedules to suit a city’s congestion level. Guidelines for scheduling conversions in real settings are furnished. So is discussion on how these schedules might be adapted to daily variations in city-wide traffic states. Roles for technology are discussed as well.     

Identifying peer states for transportation system evaluation &; policy analyses

The majority of comparisons between state transportation systems do not control for characteristics that may vary greatly between states (e.g., vehicle miles traveled). A shortcoming of such analyses is that a state’s individual characteristics can be highly influential in determining how transportation policy is set and funds are spent. The purpose of this paper is to extend previous efforts to create groups of similar peer states by developing a new methodological framework that incorporates demographic, temporal, and locational variability into the peer group delineations. We collected historical data for 42 variables on transportation infrastructure, population, economy, growth, topography and weather. To examine trends before and after the passage of ISTEA we gathered data over two time periods: 1985 through 1990 and 1995 through 2000. Using principal components analysis (PCA) we reduced variables into seven components, and then statistically clustered states into peer groups for each time period based on the components and the remaining variables. We identified a range of cluster solutions and demonstrate how cluster statistics help to describe the contextual basis behind the peer grouping. The results of this study are to provide government agencies, researchers and the public with a systematic methodological framework for identifying peer states that reflect similar attributes contributing to the development and maintenance of state transportation systems.

动力定位系统推力能力曲线计算分析

推力能力曲线与传统的动力定位能力评估结果不同,它显示着动力定位作业控制时推进系统的推力可执行域。文章通过对动力定位系统仅在力矩平衡约束下的最大推力进行求解,计算了推力能力曲线,并结合相关算例对推力能力曲线的应用进行了分析研究。研究结果表明推力能力图线尽管对于环境载荷的估算依赖很小,但对动力定位能力仍有着很好的反映。而且在动力定位作业控制时,它不但能反映动力定位系统当前的工作状态,同时对可能出现的一些临界状态做出预判,给动力定位系统操控人员提供很好的指导建议。     

基于分解策略的计算网格资源分配优化

提出多种Agent分别代表用户、服务提供者、资源提供者相互协作解决网格资源分配优化问题.采用双层市场模型解决网格系统资源的最优调度,即网格用户Agent与网格服务Agent相互协作的服务市场,以及网格服务Agent与网格资源Agent所组成的资源市场.为了降低计算复杂性,将分配优化问题分解为两个子问题,分别在资源市场和服务市场中解决.在双层市场中两个子问题所获得的优化值即为主问题的优化值.