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The periodic supply vessel planning problem (PSVPP) consists in determining a periodic schedule and the respective fleet composition for servicing offshore units on a regular basis. One of the challenges for the PSVPP is determining reliable schedules with a good compromise between reliability and cost. This work extends the PSVPP by including stochastic demand and travel time. We also introduce a novel methodology based on a voyage‐based model to deal with the schedule robustness. Basically, key statistical parameters related to the routes' demand and execution time are generated. They are used together with a set of probability combinations to incorporate the schedule reliability into the optimization model. Therefore, schedule reliability is an input parameter in the optimization model. The instances used in the study are based on real data from Brazil. A comparison of the new methodology to conventional approaches is presented, and a Monte Carlo simulation is used to evaluate the quality of the solutions. The proposed methodology is able to generate robust schedules at a lower cost compared to the conventional approaches. The proposed methodology might be applied to other stochastic problems, where schedule reliability is a key parameter for the problem. [ABSTRACT FROM AUTHOR]

This research effort is dedicated to develop and test a mathematical approach to estimate the optimal aircraft age to make decisions about its withdrawn from service, market relocation, or starting its retirement and decommissioning processes. Our method consists of a cost-benefit financial analysis based on the expected revenue from the aircraft returning to operations and the aircraft recovery process to support end-of-life decisions. The core contribution of this research is the possibility of systematically analyse opportunities to return parked aircraft to active service, considering reasonable scenarios of operating revenue improvements or operating cost reductions, postponing the aircraft retirement and decommissioning decision. It is important to highlight that only financial concerns of the end-of-life aircraft problem were analysed. Considering this managerial context, the estimation of the aircraft parking and retirement costs, the recovery of the operating revenues from its market relocation and the recovered values from its disassembly and dismantling may influence these companies' aircraft fleet planning in a well-supported manner. This research intends to fulfill the gaps in the literature regarding commercial aircraft costs and revenues incurred during its end-of-life phase, aiming to estimate how much they affect its total cost of ownership, considering aircraft owners' and operators' decision-making contexts. [ABSTRACT FROM AUTHOR]

Mining is an important economic activity and a highly complex industry. As such, it demands a complex supply chain to connect mines to clients, often involving railways, ports and long-distance maritime shipping. State-of-the-art optimization tools are an invaluable asset to help manage such a complex environment, which makes mining industry a very fertile ground for operational research applications. This paper aims to present a bibliographical review of published works involving operational research applications in the mining industry. We start by mapping applications within each isolated link of the chain. Then, we make inroads into the researches involving and connecting multiple links of the mining chain. Finally, we present summaries of our finding and pinpoint some directions for research opportunities in the mining industry. [ABSTRACT FROM AUTHOR]

Focuses on a study which proposed an alternative mixed integer linear disjunctive formulation for transmission network expansion. Classical non-linear formulation of the transmission expansion problem; Disjunctive mixed integer formulation of the transmission expansion problem; Standard and alternative disjunctive models.

The Generation Expansion Planning (GEP) process in Brazil involves computational models with a range of variables and constraints inherent in a mostly hydrothermal system. Such models generally use technical and economic parameters to represent the system, but with the growing concern about environmental and climatic issues, the need has arisen for environmental parameter analysis to promote a better representation of a more comprehensive optimum. In view of the recent Paris Agreement, through which the Brazilian government committed itself to significantly reduce its greenhouse gas emissions (GHG) by 2030, it has become essential that the GEP take into account the emission of gases. In this work, scenarios that penalize or limit the emission of greenhouse gases are created and compared inside the existent Investment Decision Model (MDI) used in Brazil. The main objective is to verify how the objective of reducing emissions would change the optimum expansion planning originally provided by the investment model. The results show that within the created scenarios, the largest reduction is achieved when considering a monetary penalty of US$ 25.00/tCO 2eq in the burning of fossil fuels for power generation. In this case, to reduce the emissions, the investment model chooses a larger expansion of wind and biomass sources with a corresponding raise in the cost of approximately 5.3%, allowing a total reduction of about 39 MtCO 2eq in relation to the reference scenario at the end of the planning horizon. • Hydrothermal Generation Expansion Planning with environmental ex-ternalities. • Scenarios that penalize or limit the emission of greenhouse gases are simulated. • The internalization of environmental externalities defines environmen-tal policies. • GHG emissions reductions can change the optimum expansion plan-ning. • A larger expansion of wind and biomass sources with a raise of 5.3% of the cost. [ABSTRACT FROM AUTHOR]

Abstract To evaluate the impacts of the Fundão tailings dam failure (Minas Gerais, Brazil) on water quality of the Doce River, we analyzed metagenomics and physicochemical parameters during the month of the disaster and again 6 and 10 months after the disaster. To compare dam conditions before and after the failure, we performed a meta-analysis of physicochemical data from a public database. Immediately after the failure, suspended particulate matter (SPM) in the Doce River was 225–1877 mg L−1. Turbidity and dissolved aluminum and iron concentrations were extremely high, whereas dissolved oxygen was below Brazilian legislation norm (<5 mg L−1) in several locations. Six months later, physicochemical values were below thresholds set by Brazilian guidelines (e.g., SPM = 8–166 mg L−1). Short-term impacts on microbial communities included an increase in Actinobacteria and Bacteroidetes and gene sequences related to microbial virulence, motility, respiration, membrane transport, iron and nitrogen metabolism, suggesting changes in microbial metabolic profiles. The 11 recovered partial genomes from metagenomes (MAGs) had genes related to Fe cycle and metal resistance. Graphical abstract Unlabelled Image Highlights • Possible effects of pollutants in Doce River after Fundão dam rupture were evaluated. • Fundão tailing induced short-term alterations in the Doce River microbiota. • Streptomycetaceae was detected as useful biomarker of environmental contamination. • Fe cycling genes were found among the 11 metagenome-assembled genomes. • 1 year post-disaster, in the wet season, Doce River still showed abnormal turbidity. [ABSTRACT FROM AUTHOR]

On November 5th, 2015, the Fundão dam rupture released >50 million m3 of ore tailings into the Doce River, Minas Gerais State, Brazil. The huge volume of mud spread along the river and reached the sea, 17 days after the disaster, in Regência, Espírito Santo State (ES). In 2018, after three years of the disaster, the impacts of the ore tailings in the marine environment are still unclear. This study aims to investigate possible short-term impacts in marine biodiversity caused by the ore tailings' mud over the reef ecosystems that are closest to the disaster area: i.e. recently discovered reefs in the southern Abrolhos Bank. A remote sensing surveillance including winds, sea surface temperature, total suspended material and watercolor (MODIS Aqua data) indicated that the iron tailings plume reached the southern portion of Abrolhos Bank on June 16th, 2016. Subsequently, to obtain further evidence of the presence of the tailings in the coral reefs, water samples were collected in a gradient spanning from the river estuary to the reefs in southern Abrolhos Bank, we also analyzed the isotopic and microbial composition of the samples, as well as the reef benthic composition. Despite no clues of negative impact on benthic (coral) communities, isotopic analysis confirmed the presence of the plume over the reefs area. This study serves as a baseline for future long-term impact assessments of the health of coral reefs in the Abrolhos Bank. Unlabelled Image • The Doce River iron tailings plume reached the Abrolhos Bank on June 16th, 2016. • Analyses of SPM confirmed the presence of the tailing plume over the reef area. • Southerly winds may cause new arrivals of the iron tailing plume to the reefs. • Abrolhos reefs may be suffering with a nutrient enrichment. [ABSTRACT FROM AUTHOR]