Energy-Aware Cloud Management through Progressive SLA Specification

Novel energy-aware cloud management methods dynamically reallocate computation across geographically distributed data centers to leverage regional electricity price and temperature differences. As a result, a managed VM may suffer occasional downtimes. Current cloud providers only offer high availability VMs, without enough flexibility to apply such energy-aware management. In this paper we show how to analyse past traces of dynamic cloud management actions based on electricity prices and temperatures to estimate VM availability and price values. We propose a novel SLA specification approach for offering VMs with different availability and price values guaranteed over multiple SLAs to enable flexible energy-aware cloud management. We determine the optimal number of such SLAs as well as their availability and price guaranteed values. We evaluate our approach in a user SLA selection simulation using Wikipedia and Grid'5000 workloads. The results show higher customer conversion and 39% average energy savings per VM.Comment: 14 pages, conferenc

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

Intraoperative use of methadone improves control of postoperative pain in morbidly obese patients: a randomized controlled study

Felipe Chiodini Machado, Claudia Carneiro de Araújo Palmeira, João Nathanael Lima Torres, Joaquim Edson Vieira, Hazem Adel Ashmawi Anesthesiology Department, hcFMUsP, Universidade de São Paulo, São Paulo, Brazil Objectives: Surgical patients still commonly experience postoperative pain. With the increasing prevalence of obesity, there is a growing demand for surgical procedures by this population. Intraoperative use of methadone has not been well assessed in this population. Materials and methods: Patients with a body mass index of 35  kg/m2 or more undergoing bariatric surgery were randomly assigned to receive either fentanyl (group F) or methadone (group M) in anesthesia induction and maintenance. The primary outcome was morphine consumption during the first 24 hours after surgery through a patient-controlled analgesia device. Secondary outcomes were pain scores at rest and while coughing, opioid related side effects, and patient satisfaction. The patients were also evaluated 3 months after surgery for the presence of pain, dysesthesia, or paresthesia at surgical site. Results: Postoperative morphine consumption was significantly higher for patients receiving fentanyl than methadone during the postoperative period at 2 hours (mean difference [MD] 6.4 mg; 95% CI 3.1–9.6; P<0.001), 2–6 hours (MD 11.4 mg; 95% CI 6.5–16.2; P<0.001), 6–24 hours (MD 10.4 mg; 95% CI 5.0–15.7; P<0.001), and 24–48 hours (MD 14.5 mg; 95% CI 3.9–25.1; P=0.01). Patients from group F had higher pain scores until 24 hours postoperatively, higher incidence of nausea and vomiting, lower satisfaction, and more evoked pain at surgical scar at the 3-month postoperative evaluation than group M. Conclusion: Intraoperative methadone can safely lower postoperative opioid consumption and improve postoperative pain scores compared with fentanyl in morbidly obese patients. Keywords: postoperative pain, bariatric surgery, acute pain, postoperative pain, methadon