Optimizing station location and fleet composition for a high-speed rail line

This paper proposes a new strategic planning model for high-speed rail ventures. It is a mixed-integer optimization model that applies to a given line and focuses on two key strategic decisions: station location and fleet composition. Our purpose is to improve on previous station location models by including fleet composition decisions. In the new model, we additionally take into account in an approximate fashion the interrelationships between strategic and subsequent tactical decisions, regarding line planning, train scheduling and fleet assignment issues. The usefulness of the model is demonstrated for a case study involving a planned Lisbon-Oporto high-speed rail line.     

A deterministic mathematical model to support temporal and spatial decisions of the soybean supply chain

A novel deterministic mathematical model is presented as part of research into a stochastic optimization model for the soybean supply chain in Brazil. The model was conceived as a tool to aid in the decision-making of any trader involved in this highly complex market. The model is intended to be applied to decisions related to tactical planning over a time span of one year. The major spatial and temporal components of the soybean complex, including transportation mode decisions, are incorporated into the model. The mathematical model is described in detail. Several stochastic parameters are used with fixed values in the deterministic model to construct various scenarios. These parameters are the purchase and sale prices of the grain on the market, the crop failure rate and the volumes of demand. The model was tested using data from a large trade in Brazil with consistent results.     

Design and planning for green global supply chains under periodic review replenishment policies

We quantify the impact of jointly optimizing strategic network design and tactical inventory planning on the cost and CO₂ emissions of multi-echelon logistics networks. The obtained insights indicate that longer optimized replenishment cycles reduce a node’s transportation cost and CO₂ emissions but increase its inventory costs. Moreover, under a fixed replenishment cycle, a node’s service level increases when supplied by a satellite warehouse. Finally: (i) the costs of implementing optimal green network design decisions could be misleading if inventory planning is neglected, (ii) greening of supply chains could become expensive, (iii) current legislative CO₂ ton prices hardly influence logistics networks.     

Design of international assembly systems and their supply chains under NAFTA

The purpose of this paper is to provide a decision support aid for the strategic design of an assembly system in the international business environment created by NAFTA. The strategic design problem is to prescribe a set of facilities, including their locations, technologies, and capacities, as well as strategic aspects of the supply chain, selecting suppliers; locating distribution centers; planning transportation modes; and allocating target levels (i.e., amounts) for production, assembly, and distribution. The objective is to maximize after-tax profits. This paper presents a mixed integer programming model that represents the complexities of the international design problem as well as relevant enterprise-wide decisions in the US–Mexico business environment under NAFTA. It deals with a broad set of design issues (e.g., bill-of-material restrictions, international financial considerations, and material flow through the entire supply chain) using effective modeling devices (e.g., linearizing non-linearities that arise in modeling transfer prices and allocating transportation charges). Examples demonstrate how managers might use the model as a decision support aid.     

Vulnerability assessment and re-routing of freight trains under disruptions: A coal supply chain network application

In this paper, we present a two-stage mixed integer programming (MIP) interdiction model in which an interdictor chooses a limited amount of elements to attack first on a given network, and then an operator dispatches trains through the residual network. Our MIP model explicitly incorporates discrete unit flows of trains on the rail network with time-variant capacities. A real coal rail transportation network is used in order to generate scenarios to provide tactical and operational level vulnerability assessment analysis including rerouting decisions, travel and delay costs analysis, and the frequency of interdictions of facilities for the dynamic rail system.     

From traditional to professional Air Navigation Service Provider: A typology of European ANSP business models

This paper proposes a business model typology based on factor analysis of mixed data sourced from the 2016 Air Traffic Management Cost Effectiveness (ACE) benchmarking report, European air navigation service provider (ANSP) websites and annual reports. It provides ANSP management insight into the key strategic business model decisions to be made, their resulting models as well as how these business model decisions contribute to ATM/CNS profits. The findings suggest that ANSPs can benefit from increasing both their level of corporatisation as level of outsourcing. The paper can be used by ANSP managers to position themselves within the European air navigation services (ANS) landscape and as a discussion starter for future business model developments; or by ANS customers to better understand the strategic objectives of the ANSPs.     

Modeling downstream petroleum supply chain: The importance of multi-mode transportation to strategic planning

This paper proposes a deterministic mixed integer linear programming (MILP) model for downstream petroleum supply chain (PSC) network to determine the optimal distribution center (DC) locations, capacities, transportation modes, and transfer volumes. The model minimizes multi-echelon multi-product cost along the refineries, distribution centers, transportation modes and demand nodes. The relationship between strategic planning and multimodal transportation is further elucidated. A case study was considered with real data from the U.S. petroleum industry and transportation networks within Geographic Information System (GIS). A scenario analysis is also conducted to demonstrate the impact of key parameters on PSC decisions and total cost.     

Strategic design and operational management optimization of a multi stage physical distribution system

Design and management of logistic networks is one of the most critical issues in supply chain management. However, the literature does not contain any effective models, methods, and applications that simultaneously support management decisions in the strategic design of the distribution system, in the operational planning and organization of vehicles, and in container trips organization adopting different modes of transportation. The aim of this paper is to illustrate an original framework for the design and optimization of a multi echelon and multi level production/distribution system that combines mixed-integer linear programming modeling with cluster analysis, heuristic algorithms, and optimal transportation rules. A significant case study is illustrated revealing the effectiveness of the approach and tools proposed.     

Endogenous control of service rates in stochastic and dynamic queuing models of airport congestion

Airport congestion mitigation requires reliable delay estimates. This paper presents an integrated model of airport congestion that combines a tactical model of capacity utilization into a strategic queuing model. The model quantifies the relationships between flight schedules, airport capacity and flight delays, while accounting for the way arrival and departure service rates can be controlled over the day to maximize operating efficiency. We show that the model estimates the average and variability of the delays observed at New York’s airports relatively well. Results suggest that delays can be extremely sensitive to even small changes in flight schedules or airport capacity.     

Coordinated capacity and demand management in a redesigned Air Traffic Management value-chain

We present a re-designed European Air Traffic Management value-chain, with a new role for the Network Manager, which coordinates capacity and demand management decisions, using economic instruments for both areas. A conceptual and mathematical model supports decision-making in that process, focusing on capacity management decisions taken at the strategic level. Total costs are minimized by jointly managing sector-opening schemes and trajectory assignments. A large-scale case study demonstrates clear trade-offs between the volume of capacity ordered and the scope of necessary demand management actions. In addition, the comparison against a baseline, which resembles the current system, shows that with the proposed concept less capacity is needed to serve the same demand, resulting in lower total cost for Aircraft Operators.     

A location-inventory-pricing model in a supply chain distribution network with price-sensitive demands and inventory-capacity constraints

This paper presents a location-inventory-pricing model for designing the distribution network of a supply chain with price-sensitive demands and inventory-capacity constraints. The supply chain has market power and uses markup pricing. An efficient Lagrangian relaxation algorithm is proposed to solve the model. Our numerical study shows that by moderately increasing the number of possible values for pricing decisions, the model can be used to find near-optimal solutions of a similar location-inventory-pricing problem with continuous pricing decisions. The approach used here to incorporate pricing decisions can be applied to other supply-chain design and planning problems with price-sensitive demands.     

Railway crew capacity planning problem with connectivity of schedules

We study a tactical level crew capacity planning problem in railways which determines the minimum required crew size in a region while both feasibility and connectivity of schedules are maintained. We present alternative mathematical formulations which depend on network representations of the problem. A path-based formulation in the form of a set-covering problem along with a column-and-row generation algorithm is proposed. An arc-based formulation of the problem is solved with a commercial linear programming solver. The computational study illustrates the effect of schedule connectivity on crew capacity decisions and shows that arc-based formulation is a viable approach.     

Determinants of information systems outsourcing in hotels from the resource‐based view: an empirical study

The objective of this study is to determine the factors affecting outsourcing of information system/information technology (IS/IT) activities in hotels from the resource‐based view of the firm. The factors considered are the conditions that the systems area resources must meet for that area to have a competitive value. The reasons, which are both strategic and tactical, are discussed. The former are mainly related to quality, improvement of service and concentration on core activities, whereas the latter are tactical or cost‐related reasons justifying the selection of the outsourcing strategy for this activity. The results indicate the factors determining IS/IT activity outsourcing are related to the creation of valuable resources and to market transaction costs, and the IS/IT area performance does not influence the decision to outsource. It is also shown that the reasons justifying outsourcing are strategic; related to the core competencies and quality of service and not to cost reduction. Copyright © 2005 John Wiley & Sons, Ltd.     

Designing a new supply chain for competition against an existing supply chain

We develop a bi-level model for designing an entrant supply chain (SC) in the presence of a pre-existing competing SC where demand is elastic with respect to price and distance. The model assumes dynamic competition between the new and pre-existing SCs in retailers’ level and probabilistic customers’ behavior. Strategic facility location and flow decisions are made while considering inventory carrying costs incurred on the operational level. We formulate the problem and propose exact and metaheuristic algorithms to solve it. The model is solved using data from a real-life case and also randomly generated test problems to extract managerial insights.     

Liner shipping cargo allocation with service levels and speed optimization

The cargo allocation problem is a key strategic problem that determines the profitability of a liner shipping network. We present a novel mixed-integer programming model for this problem that introduces service levels for transit time requirements and optimizes the vessel speed on each leg of a service. These extensions to the cargo allocation problem greatly increase its realism and value for carriers. We evaluate our model on realistic data from the LINER-LIB and perform a sensitivity analysis of transit times versus bunker costs. Furthermore, we show how carriers can use our model to make data driven decisions in their operations.     

逆向物流成本核算模型研究

在论述逆向物流成本形成机制的基础上,运用基于作业的成本分析法,构建了逆向物流运作的流程结构,并通过作业流程的分析,构建了逆向物流成本的退货成本核算模型、再加工成本核算模型、材料再生成本核算模型、产品拆卸成本核算模型、包装物和载运品回收成本核算模型及废弃处理成本核算模型。     

Dynamic network design for reverse logistics operations under uncertainty

The design of reverse logistics network has attracted growing attention with the stringent pressures from environmental and social requirements. In general, decisions about reverse logistics network configurations are made on a long-term basis and factors influencing such reverse logistics network design may also vary over time. This paper proposes dynamic location and allocation models to cope with such issues. A two-stage stochastic programming model is further developed by which a deterministic model for multiperiod reverse logistics network design can be extended to account for the uncertainties. A solution approach integrating a recently proposed sampling method with a heuristic algorithm is also proposed in this research. A numerical experiment is presented to demonstrate the significance of the developed stochastic model as well as the efficiency of the proposed solution method.     

Long-term evolution of airport networks: Optimization model and its application to the United States

In this article, we introduce an optimization model aimed to assist aviation authorities in their strategic decisions regarding the long-term expansion of a network of airports. The objective is to maximize total system throughput for a given budget taking into account the capacity of the airports and the impact of travel costs upon demand. The results that can be obtained through the application of the model are first illustrated for a hypothetical small-size network and then in a study regarding the evolution of the network of the principal airports of the United States.     

A top-down approach and a decision support system for the design and management of logistic networks

This paper presents an original top-down approach, made of original models and solving methods, and a decision support system (DSS) for the execution of the strategic planning, the tactical planning and the operational planning in a multi-echelon multi-stage multi-commodity and multi-period production, distribution and transportation system. The DSS is a software platform useful for the design, management and control of real instances. It can efficiently supports the decision making process of logistic managers and planners of large enterprises as multi-facilities companies and production–distribution networks. A significant case study is illustrated. The results obtained by the application of different problem settings are compared and discussed.     

A top-down approach and a decision support system for the design and management of logistic networks

This paper presents an original top-down approach, made of original models and solving methods, and a decision support system (DSS) for the execution of the strategic planning, the tactical planning and the operational planning in a multi-echelon multi-stage multi-commodity and multi-period production, distribution and transportation system. The DSS is a software platform useful for the design, management and control of real instances. It can efficiently supports the decision making process of logistic managers and planners of large enterprises as multi-facilities companies and production–distribution networks. A significant case study is illustrated. The results obtained by the application of different problem settings are compared and discussed.