Multiple Steady States in Heterogeneous Azeotropic Distillation

In this article we study multiple steady states in ternary heterogeneous azeotropic distillation. We show that in the case of infinite reflux and an infinite number of trays one can construct bifurcation diagrams on physical grounds with the distillate flow as the bifurcation parameter. Multiple steady states exist when the distillate flow varies non-monotonically along the continuation path of the bifurcation diagram. We show how the distillate and bottom product paths can be located for tray or packed columns, with or without decanter and with different types of condenser and reboiler. We derive a necessary and sufficient condition for the existence of these multiple steady states based on the geometry of the product paths. We also locate in the composition triangle the feed compositions that lead to these multiple steady states. We show that the prediction of the existence of multiple steady states in the case of infinite reflux and an infinite number of trays has relevant implications for columns operating at finite reflux and with a finite number of trays

Multiple Steady States in Homogeneous Azeotropic Distillation

In this article we study multiple steady states in ternary homogeneous azeotropic distillation. We show that in the case of infinite reflux and an infinite number of trays one can construct bifurcation diagrams on physical grounds with the distillate flow as the bifurcation parameter. Multiple steady states exist when the distillate flow varies non-monotonically along the continuation path of the bifurcation diagram. We derive a necessary and sufficient condition for the existence of these multiple steady states based on the geometry of the distillation region boundaries. We also locate in the composition triangle the feed compositions that lead to these multiple steady states. We further note that most of these results are independent of the thermodynamic model used. We show that the prediction of the existence of multiple steady states in the case of infinite reflux and an infinite number of trays has relevant implications for columns operating at finite reflux and with a finite number of trays. Using numerically constructed bifurcation diagrams for specific examples, we show that these multiplicities tend to vanish for small columns and/or for low reflux flows. Finally, we comment on the effect of multiplicities on column design and operation for some specific examples

Trends in health facility deliveries and caesarean sections by wealth quintile in Morocco between 1987 and 2012.

OBJECTIVES: To examine trends in the utilisation of facility-based delivery care and caesareans in Morocco between 1987 and 2012, particularly among the poor, and to assess whether uptake increased at the time of introduction of policies or programmes aimed at improving access to intrapartum care. METHODS: Using data from nationally representative household surveys and routine statistics, our analysis focused on whether women delivered within a facility, and whether the delivery was by caesarean; analyses were stratified by relative wealth quintile and public/private sector where possible. A segmented Poisson regression model was used to assess whether trends changed at key events. RESULTS: Uptake of facility-based deliveries and caesareans in Morocco has risen considerably over the past two decades, particularly among the poor. The rate of increase in facility deliveries was much faster in the poorest quintile (annual increase RR: 1.09; 95% CI: 1.07-1.11) than the richest quintile (annual increase RR: 1.01; 95% CI: 1.02-1.02). A similar pattern was observed for caesareans (annual increase among poorest RR: 1.13; 95% CI: 1.07-1.19 vs. annual increase among richest RR: 1.08; 95% CI: 1.06-1.10). We found no significant acceleration in trend coinciding with any of the events investigated. CONCLUSIONS: Morocco's success in improving uptake of facility deliveries and caesareans is likely to be the result of the synergistic effects of comprehensive demand and supply-side strategies, including a major investment in human resources and free delivery care. Equity still needs to be improved; however, the overall trend is positive

Multiple Steady States in Heterogeneous Azeotropic Distillation

In this article, we study multiple steady states in ternary heterogeneous azeotropic distillation. We show that in the case of infinite reflux and an infinite number of trays, one can construct bifurcation diagrams on physical grounds with the distillate flow as the bifurcation parameter. Multiple steady states exist when the distillate flow varies nonmonotonically along the continuation path of the bifurcation diagram. We show how the distillate and bottom product paths can be located for tray or packed columns, with or without decanter and with different types of condenser and reboiler. We derive a necessary and sufficient condition for the existence of these multiple steady states based on the geometry of the product paths. We also locate in the composition triangle the feed compositions that lead to these multiple steady states. We show that the prediction of the existence of multiple steady states in the case of infinite reflux and an infinite number of trays has relevant implications for columns operating at finite reflux and with a finite number of trays

Implementing a maternal mortality surveillance system in Morocco challenges and opportunities

Objective To describe the development of the maternal death surveillance system (MDSS) in Morocco and discuss the initial results. Method The nationwide MDSS was implemented in 2009 with the involvement of health professionals and local authorities. It comprises (i) notification of all deaths of women of reproductive age (from 15 to 49years); (ii) a preliminary survey to identify pregnancy-related deaths; (iii) a confidential enquiry into all pregnancy-related deaths. The information thus obtained describes socio-demographic characteristics of the women, their obstetric and medical history, the mode of delivery, its follow-up and the medical cause of death. Results From 1st of January 2009 to 31st of December 2009, 3814 deaths of women of reproductive age were recorded, and a total of 436 pregnancy-related deaths were identified, with 73.4% of those occurring in health facilities. Among the 313 reviewed records, 80.8% were direct obstetric deaths, and 13.5% were classified as indirect. Haemorrhage was the first direct obstetric cause of death (33%). Heart disease was the main indirect obstetric cause of death (39% of indirect causes). Conclusion The Moroccan MDSS is a powerful tool for understanding the causes and circumstances of maternal deaths. However, challenges remain regarding the full coverage of the system, the decentralisation of the data entry and analysis and the completeness of medical records

Modularity and openness in modeling MAS (abstract)

We revisit the formalism of modular interpreted systems (MIS) which encourages modular and open modeling of synchronous multi-agent systems. The original formulation of MIS did not live entirely up to its promise. In this paper, we propose how to improve modularity and openness of MIS by changing the structure of interference functions. These relatively small changes allow for surprisingly high flexibility when modeling actual multi-agent systems. Perhaps more importantly, we propose how the notions of multi-agency and openness, crucial for multi-agent systems, can be precisely defined based on their MIS representations