Large-scale unit commitment under uncertainty: an updated literature survey

The Unit Commitment problem in energy management aims at finding the optimal production schedule of a set of generation units, while meeting various system-wide constraints. It has always been a large-scale, non-convex, difficult problem, especially in view of the fact that, due to operational requirements, it has to be solved in an unreasonably small time for its size. Recently, growing renewable energy shares have strongly increased the level of uncertainty in the system, making the (ideal) Unit Commitment model a large-scale, non-convex and uncertain (stochastic, robust, chance-constrained) program. We provide a survey of the literature on methods for the Uncertain Unit Commitment problem, in all its variants. We start with a review of the main contributions on solution methods for the deterministic versions of the problem, focussing on those based on mathematical programming techniques that are more relevant for the uncertain versions of the problem. We then present and categorize the approaches to the latter, while providing entry points to the relevant literature on optimization under uncertainty. This is an updated version of the paper "Large-scale Unit Commitment under uncertainty: a literature survey" that appeared in 4OR 13(2), 115--171 (2015); this version has over 170 more citations, most of which appeared in the last three years, proving how fast the literature on uncertain Unit Commitment evolves, and therefore the interest in this subject

Evaluating prevalence of external injuries on nesting loggerhead sea turtles Caretta caretta in southeastern Florida, USA

Sea turtles face both anthropogenic and natural threats including boat strikes, fisheries, pollution, and predator attacks. Injuries from anthropogenic sources are more common than naturally caused injuries. The goal of this study was to determine prevalence and cause (e.g. boat strike, entanglement, hook, shark bite) of injuries on nesting loggerhead sea turtles Caretta caretta on Juno and Jupiter beaches, Florida, USA. During the 2019 and 2020 nesting seasons, 450 loggerhead females were examined for external injuries. Injuries were categorized by anatomic location, condition, and cause. We found that 24% of loggerheads had at least 1 injury. Of the 111 injuries found on 107 nesting females, 88% were healed, 9% were partially healed with some scarred tissue, and 3% were fresh injuries. Most injuries (55%) were lateral injuries on the carapace or appendages. We were able to attribute 60 injuries to a specific cause. Boat strikes accounted for 75% of the 60 injuries, shark bites accounted for 15%, fishing hooks accounted for 7%, and entanglements accounted for the remaining 3%. This study provides new insight into the prevalence of anthropogenic injuries relative to natural injuries in loggerhead sea turtles nesting in the most densely nested beach in the Western Hemisphere and can be used to improve conservation management plans through implementation of fishing and/or boating restrictions in the nesting and foraging areas most commonly frequented by sea turtles.</jats:p

Updated global conservation status and priorities for marine turtles

Assessing conservation status and pursuing applicable management priorities for marine megafauna across multiple scales pose significant challenges. Because marine turtles exemplify these challenges, the IUCN Marine Turtle Specialist Group (MTSG) developed the ‘conservation priorities portfolio’ (CPP) framework in 2011 to evaluate population risk and threats for regional management units (RMUs). Here, the MTSG has updated the 2011 CPP framework through an inclusive assessment process. Expert elicitation results involving 145 individuals from 50 countries suggests that marine turtle conservation status appears to be improving, but significant challenges remain. Since the previous assessment, long-term abundance trends increased on average, and threat impact scores improved for nearly twice as many RMUs (53%) as worsened (28%) (≥10% threshold for changes in numeric scores). While expert-assessed threat impacts have generally decreased, fisheries bycatch remains the highest scored threat across regions and species. Risk-threat staus improved for most (54%) RMUs. Over 40% of RMUs were scored as low risk-low threats, of which 8 were green turtles Chelonia mydas RMUs. Less than 20% of RMUs were scored as high risk-high threats, of which 4 were leatherback turtles Dermochelys coriacea. Most high risk-high threats RMUs were in the Pacific Ocean, while most low risk-low threats RMUs were in the Atlantic Ocean. Eleven RMUs were evaluated as having critical data needs. Our results—also provided through an interactive data dashboard—underscore the importance of context-specific planning to effectively target limited conservation resources. Future assessments should further prioritize inclusion of under-represented topics, researchers, and regions to better address multi-faceted conservation challenges