A MILP model for planning the trips of dynamic positioned tankers with variable travel time

The transportation of the crude oil produced in offshore oilfields to onshore terminals is performed by vessels, known as shuttle tankers. Scheduling shuttle-tanker operations entails solving complex problems to ensure a timely offloading of the platforms, taking into account several logistics and inventory constraints. This work proposes a new MILP formulation that advances previous works by considering variable travel time between platforms and terminals. The combination of the MILP formulation with an optimization solver constitutes a decision-support tool to aid engineers reach optimal decisions for a planning horizon. To handle large-scale instances, rolling-horizon and relax-and-fix strategies are proposed.     

Strategies,market concentration and hegemony in chemical parcel tanker shipping, 1960–1985

The article analyses the emergence of chemical shipping as a specialised shipping segment. In the 1950s and 1960s seaborne transport of chemicals was characterised by rapid technological development, based on the introduction of parcel tankers, which could carry chemicals in bulk. By the early 1970s two Norwegian companies had built up substantial market shares, but were challenged by financially stronger British companies. The article traces the background of the main companies involved in chemical shipping in the 1970s, by which stage market concentration was evident. We look at their entry into the market and their strategies. First mover advantages, determination to remain market leaders, fleet structure and timing go a long way to explaining why by the mid-1980s the Norwegians had managed to fend off the British challenge.     

Analytical models of rail transportation service in the grain supply chain: Deconstructing the operational and economic advantages of shuttle train service

This paper introduces conceptual and mathematical models of the domestic grain supply chain incorporating trucking, elevator storage, and rail transportation. We compare conventional rail service supported by country elevators with shuttle service supported by terminal elevators across three critical transportation service dimensions: travel time, cost, and capacity. Even after taking into account trucking and elevator storage, the time and cost model results indicate that shuttle service transports grain faster and reduces logistical supply chain costs, respectively, relative to conventional service. The rail capacity model results demonstrate that shifting grain from conventional to shuttle service significantly increases rail capacity.     

散化船透气管系简介及检验要点探讨

本文通过对散化船的开式透气系统和控制式透气系统的介绍,分析了其设置的原因,引出规范中对透气系统的要求,从而提出针对散化船透气系统的检验要点,为同类船舶透气管系的安装与检验工作提供参考。     

航天飞机的地面保障系统

美国航天飞机的地面保障系统包括航天跟踪和数据网(STDN)、网控制中心(NCC)、航天指控中心(MCC)和有效载荷操作控制中心(POCC)。本文综述上述各部分的组成、任务及它们之间的关系,并就我国载人航天测控通信网的操作控制中心的建设提出了基本看法。     

The influence of charterers and owners on bulk shipping freight rates

We propose a model for freight rate formation in individual contracts that incorporates charterer and owner heterogeneity and owner–charterer match effects. We estimate fixed effect regressions and implement a variance decomposition for 2863 VLCC tanker and 1789 Capesize fixtures between 2011 and 2014. Although market conditions and routes remain the most influential covariates, the characteristics of charterers, owners and of their matches are also significant microeconomic determinants of the freight rate level. The contribution of the charterer fixed effect is large in the VLCC market, while the charterer and match effects are large contributors to the Capesize spot freight rate.     

楼巴与城市机动性探析——以广州碧桂园凤凰城为例

广州是中国房地产最早开始市场化和民营化的地方。随着广州城市各空间的拓展以及居住新城的出现,产生了大量的通勤交通的需求。在城市公共交通网络体系未成熟之时,楼巴这种由开发商运营的服务成为居民出行主要的交通方式。