Optimization of Steel Production Scheduling with Complex TimeSensitive Electricity Cost

<p>Energy-intensive industries can take advantage of process flexibility to reduce operating costs by optimal scheduling of production tasks. In this study we develop a MILP formulation to extend a continuous-time model with energy-awareness to optimize the daily production schedules and the electricity purchase including the load commitment problem. The sources of electricity that are considered are purchase on volatile day-ahead markets, time-of-use (TOU) contracts and base load contracts, as well as onsite generation. The possibility to sell electricity back to the grid is also included. The model is applied to the melt shop section of a stainless steel plant. Due to the large-scale nature of the combinatorial problem which prevents the solution of a monolithic model to nearoptimality, we propose a bi-level heuristic algorithm to tackle instances of industrial size. Case study scenarios show that the potential impact of high prices in the day-ahead markets of electricity can be mitigated by jointly optimizing the production schedule and the associated net electricity consumption cost.</p

Multisector intervention to accelerate reductions in child stunting: an observational study from 9 sub-Saharan African countries

Background: In sub-Saharan Africa, ;40% of children ,5 y old are stunted, with levels that have remained largely unchanged over the past 2 decades. Although the complex determinants of undernutrition are well recognized, few studies have evaluated strategies that combine nutrition-specific, health-based approaches with food system– and livelihood-based interventions. Objective: We examined changes in childhood stunting and its determinants after 3 y of exposure to an integrated, multisector intervention and compared these changes with national trends. Design: A prospective observational trial was conducted across rural sites in 9 sub-Saharan African countries with baseline levels of childhood stunting .20%. A stratified random sample of households and resident children ,2 y old from villages exposed to the program were enrolled in the study. Main outcome measures included principal determinants of undernutrition and childhood stunting, which was defined as a height-for-age z score less than 22. National trends in stunting were generated from demographic and health surveys. Results: Three years after the start of the program in 2005–2006, consistent improvements were observed in household food security and diet diversity, whereas coverage with child care and diseasecontrol interventions improved for most outcomes. The prevalence of stunting in children ,2 y old at year 3 of the program (2008–2009) was 43% lower (adjusted OR: 0.57; 95% CI: 0.38, 0.83) than at baseline. The average national stunting prevalence for the countries included in the study had remained largely unchanged over the past 2 decades. Conclusion: These findings provide encouraging evidence that a package of multisector interventions has the potential to produce reductions in childhood stunting. Am J Clin Nutr doi: 10. 3945/ajcn.111.020099