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Publications

Publications by João Claro

2014

Waste in non-value-added suppression activities: simulation analysis of the impact of rekindles and false alarms on the forest fire suppression system

Authors
Pacheco, AP; Claro, J; Oliveira, T;

Publication
Advances in forest fire research

Abstract

2013

Forest fire management to avoid unintended consequences: A case study of Portugal using system dynamics

Authors
Collins, RD; de Neufville, R; Claro, J; Oliveira, T; Pacheco, AP;

Publication
JOURNAL OF ENVIRONMENTAL MANAGEMENT

Abstract
Forest fires are a serious management challenge in many regions, complicating the appropriate allocation to suppression and prevention efforts. Using a System Dynamics (SD) model, this paper explores how interactions between physical and political systems in forest fire management impact the effectiveness of different allocations. A core issue is that apparently sound management can have unintended consequences. An instinctive management response to periods of worsening fire severity is to increase fire suppression capacity, an approach with immediate appeal as it directly treats the symptom of devastating fires and appeases the public. However, the SD analysis indicates that a policy emphasizing suppression can degrade the long-run effectiveness of forest fire management. By crowding out efforts to preventative fuel removal, it exacerbates fuel loads and leads to greater fires, which further balloon suppression budgets. The business management literature refers to this problem as the firefighting trap, wherein focus on fixing problems diverts attention from preventing them, and thus leads to inferior outcomes. The paper illustrates these phenomena through a case study of Portugal, showing that a balanced approach to suppression and prevention efforts can mitigate the self-reinforcing consequences of this trap, and better manage long-term fire damages. These insights can help policymakers and fire managers better appreciate the interconnected systems in which their authorities reside and the dynamics that may undermine seemingly rational management decisions.

2014

A hybrid approach for integrated healthcare cooperative purchasing and supply chain configuration

Authors
Rego, N; Claro, J; de Sousa, JP;

Publication
HEALTH CARE MANAGEMENT SCIENCE

Abstract
This paper presents an innovative and flexible approach for recommending the number, size and composition of purchasing groups, for a set of hospitals willing to cooperate, while minimising their shared supply chain costs. This approach makes the financial impact of the various cooperation alternatives transparent to the group and the individual participants, opening way to a negotiation process concerning the allocation of the cooperation costs and gains. The approach was developed around a hybrid Variable Neighbourhood Search (VNS)/Tabu Search metaheuristic, resulting in a flexible tool that can be applied to purchasing groups with different characteristics, namely different operative and market circumstances, and to supply chains with different topologies and atypical cost characteristics. Preliminary computational results show the potential of the approach in solving a broad range of problems.

2017

Is Portugal's forest transition going up in smoke?

Authors
Oliveira, TM; Guiomar, N; Oliveira Baptista, FO; Pereira, JMC; Claro, J;

Publication
LAND USE POLICY

Abstract
The turnarounds from decrease to expansion in forest areas that took place during the last century have been examined through the lens of forest transition theory (FTT). Among temperate and Mediterranean European countries that have seen an expansion of forest cover, Portugal stands out as the only case in which this trend has recently been reverted. In this study, we explicitly map and document the forest transition (FT) in the country over the period 1907-2006, and investigate when and where forest transition happened de facto, and which were the land use transition pathways that resulted from the shrublands, agriculture, and forest interplay dynamics. After thematic and geometric harmonization of land cover maps from 1907, 1955, 1970, 1990, and 2006, a cluster analysis established four typologies, and a transition matrix was constructed to assess land cover dynamics. We found that up to 1955, FT occurred simultaneously with agricultural expansion, as shrubland areas diminished. Afterwards, with the retraction of agricultural area and the consequential decoupling of forest management from local actors, FT gained momentum and expanded up to the 1990s. While during the first half of the 20th century, forest expansion followed the "Scarcity" and "State Policy" pathways fostered by local socio-ecological feedback loops, throughout the second half of the century forest transition was driven by exogenous socio-economic forces, following "Economic Development" and "Globalization" pathways. We show how, despite these forces, FT can be derailed by endogenous factors such as wildfires, which limited and in some areas even reverted the afforestation process, initiating a deforestation phase. Since the necessary conditions for FT (technology shift, urbanization, agriculture retraction and public afforestation programs) were available in mainland Portugal, we advance the hypothesis that critical wildfire risk governance deficits may have been responsible for arresting FT. Considering the critical role of forests and other wooded areas in supporting climate change mitigation and sustainable development, our work provides useful evidence and insights for public decision makers on previously unaddressed dimensions of FTT.

2014

Optimization of Power Flow with Energy Storage Using Genetic Algorithms

Authors
Leite, V; Silva, C; Claro, J; Sousa, JMC;

Publication
2014 IEEE CONGRESS ON EVOLUTIONARY COMPUTATION (CEC)

Abstract
This paper applies genetic algorithms to optimize the operation of a transmission network with energy storage capabilities, to optimize its costs, which include both generation and storage costs, for cases when the data inherent to the system is assumed to be perfectly known. The problem is formulated through the DC optimal power flow equations, including losses across the transmission lines, therefore allowing solutions regarding the network generation costs to be obtained, with and without storage. In this way, the financial impact inherent to the usage of energy storage can be derived. Since we are dealing with a large combinatorial problem, the search throughout the solution space was done by means of the Genetic Algorithms. The solutions consist of the storage device's charging or discharging rate at which it must be operating during each sub-interval considered for the simulations. The results delivered by the GA have proven the profitability of including energy storage capabilities in the transmission network of Sao Miguel (Portugal) and the usefulness of such algorithm in a real world application.

2017

Dynamic evolution of European airport systems in the context of Low-Cost Carriers growth

Authors
Jimenez, E; Claro, J; de Sousa, JP; de Neufville, R;

Publication
JOURNAL OF AIR TRANSPORT MANAGEMENT

Abstract
Airport systems adapted to the influx of Low-Cost Carriers (LCC) as the segment grew in prominence in the European market during the last decades. The generalised perspective that LCCs are attached to remote secondary airports is being increasingly challenged by recent moves of the largest European LCC. The reality is that the impact of LCCs has spread to most commercial airports in Europe, primary and secondary alike. Yet, despite valuable insights on the evolution of airline networks, the existing literature lacks a clear understanding of why this has occurred. This paper explains the dynamics in the evolution of airports systems that resulted in significant growth for the low-cost segment in Europe. A multiple case study involving 42 European airports was used to identify the mechanisms that triggered the traffic patterns leading to the ascendency of LCCs in their respective airport systems. Understanding these mechanisms may prove valuable for supporting airport strategic planning.

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