16 research outputs found

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

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    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

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    Breaking barriers to novel analgesic drug development

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    Terutroban versus aspirin in patients with cerebral ischaemic events (PERFORM): a randomised, double-blind, parallel-group trial

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    Background: Patients with ischaemic stroke or transient ischaemic attack (TIA) are at high risk of recurrent stroke or other cardiovascular events. We compared the selective thromboxane-prostaglandin receptor antagonist terutroban with aspirin in the prevention of cerebral and cardiovascular ischaemic events in patients with a recent non-cardioembolic cerebral ischaemic event. <p/>Methods: This randomised, double-blind, parallel-group trial was undertaken in 802 centres in 46 countries. Patients who had an ischaemic stroke in the previous 3 months or a TIA in the previous 8 days were randomly allocated with a central interactive response system to 30 mg per day terutroban or 100 mg per day aspirin. Patients and investigators were masked to treatment allocation. The primary efficacy endpoint was a composite of fatal or non-fatal ischaemic stroke, fatal or non-fatal myocardial infarction, or other vascular death (excluding haemorrhagic death). We planned a sequential statistical analysis of non-inferiority (margin 1·05) followed by analysis of superiority. Analysis was by intention to treat. The study was stopped prematurely for futility on the basis of the recommendation of the Data Monitoring Committee. This study is registered, number ISRCTN66157730. <p/>Findings: 9562 patients were assigned to terutroban (9556 analysed) and 9558 to aspirin (9544 analysed); mean follow-up was 28·3 months (SD 7·7). The primary endpoint occurred in 1091 (11%) patients receiving terutroban and 1062 (11%) receiving aspirin (hazard ratio [HR] 1·02, 95% CI 0·94–1·12). There was no evidence of a difference between terutroban and aspirin for the secondary or tertiary endpoints. We recorded some increase in minor bleedings with terutroban compared with aspirin (1147 [12%] vs 1045 [11%]; HR 1·11, 95% CI 1·02–1·21), but no significant differences in other safety endpoints. <p/>Interpretation: The trial did not meet the predefined criteria for non-inferiority, but showed similar rates of the primary endpoint with terutroban and aspirin, without safety advantages for terutroban. In a worldwide perspective, aspirin remains the gold standard antiplatelet drug for secondary stroke prevention in view of its efficacy, tolerance, and cost
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