Robust optimization for United States Department of Agriculture food aid bid allocations

The U.S. Department of Agriculture (USDA) currently uses a bidding system to determine carriers and suppliers that would partner in providing food aid annually in response to global emergencies and famine. We mimic the USDA approach via a robust optimization model featuring box and ellipsoid uncertainty frameworks to account for uncertainties in demand, supplier and carrier bid prices. Through a case study utilizing historical invoice data, we demonstrate our model applicability in improving ocean carrier and food supplier bid pricing strategy and similar supply chain network optimization problems. Through a validation algorithm we demonstrate the value of our robust models.     

A metaheuristic approach to the reliable location routing problem under disruptions

This paper examines a reliable capacitated location–routing problem in which depots are randomly disrupted. Customers whose depots fail must be reinserted into the routes of surviving depots. We present a scenario-based mixed-integer programming model to optimize depot location, outbound delivery routing, and backup plans. We design a metaheuristic algorithm that is based on a maximum-likelihood sampling method, route-reallocation improvement, two-stage neighborhood search and simulated annealing. Numerical tests show that the heuristic is able to generate results that would keep operating costs and failure costs well balanced. Managerial insights on scenario identification, facility deployment and model simplification are drawn.     

Suburbanization and highways in Spain when the Romans and the Bourbons still shape its cities

We estimate the effects of highways on the suburbanization of Spanish cities. Based on Spain’s historical roads – the almost 2000 years old Roman roads and the 1760 Bourbon roads –, we rely on an instrumental variables (IV) strategy because of the endogeneity of highway provision. Our results show that, first, each highway emanating from central cities caused an 8–9% decline in central city population between 1960 and 2011. Second, each highway ray fostered a 20% population growth in the suburbs, in particular in suburban municipalities where ramps were located. Finally, we confirm the increasing role of highways on shaping urban form: each additional kilometer closer to the nearest highway ramp increased municipal density growth by an 8%.     

Supply chain design under quality disruptions and tainted materials delivery

Events such as the 2008 Heparin tragedy, in which patients lost their lives due to tainted pharmaceuticals, highlight the necessity for supply chain designers and planners to consider the risk of even low probability incidents in supply chains. The goal of this research is to design a single-period, single-product supply chain model with capacitated facilities to hedge against the possibility of sending tainted materials to consumers. Given that our mixed-integer stochastic model is NP-hard, we develop efficient heuristic and metaheuristic algorithms to obtain acceptable solutions. Computational experience is presented and discussed.     

Truck and trailer scheduling in a real world,dynamic and heterogeneous context

We present a new variant of the Vehicle Routing Problem based on a real industrial scenario. This VRP is dynamic and heavily constrained and uses time-windows, a heterogeneous vehicle fleet and multiple types of job. A constructive solver is developed and tested using dynamic simulation of real-world data from a leading Scottish haulier. Our experiments establish the efficiency and reliability of the method for this problem. Additionally, a methodology for evaluating policy changes through simulation is presented, showing that our technique supports operations and management. We establish that fleet size can be reduced or more jobs handled by the company.     

Telecommunications/ transportation substitution and energy conservation: Part 1

The substitution of telecommunications for transportation is held to have major potential for increasing energy conservation within the USA, other developed nations, and even developing nations. This article is the first of a two-part re-examination of the substitution hypothesis based on research and experience of the past decade. This part examines the theoretical potential of telecommunications-transportation substitution for energy conservation, and reviews recent research both on public attitudes towards substitution of telecommunications for travel and on the operational experience with substitution experiments in organizations. Part 2, which appears in the June 1982 issue of Telecommunications Policy, examines the major factors which influence whether individuals and institutions will in fact choose telecommunications over travel, and then discusses government policy which could facilitate telecommunications substitution for travel.     

铁路短期变动成本的特征及计算方法探讨

根据铁路短期变动成本的变化频繁性、非连续性、与运量关系复杂性和不可归依性4个特征,提出铁路短期变动成本的计算方法和步骤。首先将企业总成本划分为固定成本和变动成本,然后分别计算直接变动成本的支出率、间接变动成本的附加率、联合产品的总变动成本和个别产品的变动成本等。     

从"畅通工程"看我国城市建设和交通管理等部门的合作协调机制

近10年来,以北京、上海、广州等为典型代表的中国城市所出现的交通问题是空前严重的.所以, 国家在2000年提出了"畅通工程"作为一个重要对策.目前,"畅通工程"已实施1年多,它给人们以什么启示?在此基础上,今后我国城市建设和交通管理等部门的合作协调又该如何进行?对此,作者进行了探讨.     

粤港澳大湾区城际铁路公交化运营模式探讨

随着产业、就业、经济、资源的深度融合,粤港澳大湾区各城市呈现出“一座城”的发展态势,区域内城际铁路快速发展。通过对粤港澳大湾区城际铁路客流特征进行分析,梳理目前大湾区城际铁路运营模式,进一步设计大湾区城际铁路公交化运营模式,并挖掘传统铁路运营模式中阻碍城际旅客便捷化出行的关键环节,提出大湾区城际铁路公交化运营发展对策,为粤港澳大湾区城际铁路公交化运营组织提供设计参考,以更好地促进区域交通一体化,服务于城际间区域联动发展。     

自贸港背景下海南与南太平洋岛国外贸发展思考

2018年4月13日,在海南省经济特区创办30周年大会的讲话上,以习近平同志为核心的党中央决定在海南设立自由贸易区,建设首个"中国特色自由贸易港"。党中央赋予海南的重大使命和历史责任,将为海南省的发展带来重大的契机。本文以海南自由贸易区(港)的政策条件为大背景,分析海南农业发展具有的优势,并以南太平洋岛国作为研究对象,深入分析海南省和南太平洋岛之间的区位优势,将两个地方的优势进行互补,从而促进双方经济的飞跃发展,实现双赢。