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

Comparison of intra and post-operative complication rates among surgical approaches in Total Hip Arthroplasty: A systematic review and meta-analysis

Background: Various surgical approaches exist for Total Hip Arthroplasty (THA), but approach specific complication rates remain unknown. The purpose of this systematic review and meta-analysis was to compare rates of common complications between surgical approaches. Methods: Four electronic databases (Medline, Embase, AMED, Ovid Healthstar) were searched from inception to June 2019. Three pairs of reviewers were involved in determining eligibility, rating internal and external validity, and data extraction. Pooled estimates were generated using a random-effects model and relative risk (RR) was calculated for dislocation, intraoperative and early postoperative fracture, early infection, deep vein thrombosis (DVT), wound complication, and failure of implant ingrowth between four approaches (posterior, anterior, direct lateral, and anterolateral). Results: Sixty-nine studies (n = 283,036) were included with nineteen randomized control trials, fourteen prospective cohort, and thirty-six retrospective cohort studies (included studies ranged from 1987 to 2019). When compared to the posterior approach, the risk for dislocation was significantly lower in the anterior (RR 0.66, 95% CI 0.54-0.77, p \u3c 0.01), anterolateral (RR 0.50, 95% CI 0.32-0.77, p = 0.03) and lateral (RR 0.74, 95% CI 0.58-0.96, p = 0.02). When compared to the posterior approach, we found higher risk of loosening in the anterolateral (RR 1.89, 95% CI 1.59-2.25, p \u3c 0.01) and lateral (RR 1.21, 95% CI 1.02-1.44, p = 0.03). Overall, evidence was deemed very low and low-quality following GRADE assessment. Conclusion: Our findings reveal that the posterior approach was associated with a higher risk of dislocation (compared to the anterior, lateral, and anterolateral) but lower risk of loosening (compared to the lateral and anterolateral approach). However, the large number of cohorts and imprecision due to low sample size for most pooled comparisons was still insufficient to confidently conclude that one approach is superior to another. Each approach has its own strengths and weaknesses, and surgeons can use the approach they are most comfortable with

Individual variability in the awareness of odors: demographic parameters and odor identification ability

Human chemosensation can be strongly influenced by how much attention people pay to chemosensory stimuli (e.g., Marks and Wheeler in Chem Senses 23:19–29, 1998; Prescott et al. in Chem Senses 29:331–340, 2004). In a recent study, a scale has been devised (i.e., the Odor Awareness Scale; OAS; see Smeets et al. in Chem Senses 33:725–734, 2008) to investigate the level of awareness people have of the available odorants in the environment. Here, we explored whether a variant (Italian version) of the OAS could be used to discriminate between different groups of participants in terms of olfactory abilities (i.e., performance in an odor identification task) and/or personal/demographic characteristics (e.g., gender, age, etc.). Ninety-eight participants underwent this study that was composed of a personal detail questionnaire, the OAS, and a deep investigation of odor identification ability based on a large variety of odor stimuli. During 6 testing sessions, a total of 72 odor stimuli were evaluated: 36 aromas in vapor phase presented in vials and 36 chemical compounds in hydroalcoholic solutions. The results did not indicate any relationships between the participants’ declared awareness of odors and the real performance in the identification test. However, differences in the awareness of odors were found as a function of a number of personal factors such as, for example, gender (with females showing higher scores than males) or age (with younger collecting lower scores than older participants). In conclusion, we could not predict from modified OAS scores the participants’ specific ability to identify odors. Nevertheless, we could extend the scale’s characterization by highlighting different connections between OAS scores and individual parameters