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Le 27 décembre 2007, la ville de Rawalpindi, au Pakistan, est la proie de violentes émeutes, suite à l’assassinat de Benazir Bhutto, principale opposante au régime en place. Dans la foule, Sarah Caron, photographe française, saisit avec son appareil les moindres détails de la scène. Mais très vite, la jeune femme est repérée et se retrouve poursuivie, craignant pour sa vie. Un mois plus tôt, Sarah rencontrait Benazir Bhutto afin de réaliser une série de portraits commandée par le magazine Time. Une entrevue difficilement décrochée et qui, par un pur hasard, survenait le jour même de l’assignation à résidence de l’opposante. Une aubaine pour Sarah : pendant 4 jours, elle se retrouvait aux premières loges de l’actualité ! De jour, elle mitraillait les lieux, de nuit, elle transférait ses clichés. En immersion totale et au gré des commandes, la jeune femme passe cette année-là du monde de l’élite pakistanaise à celui des talibans, avec l’aide d’un fier guerrier pachtoune. Son objectif est une arme dont elle se sert pour frapper les esprits et franchir les frontières, qu’elles soient physiques ou culturelles, et ce malgré le danger des lieux et des situations.

Roasting, smelting and converting are pyrometallurgical techniques used to eliminate gangue rock from sulfide ores and produce a saleable metal product. Due to the large amount of sulfur present in sulfide ores, the off-gas produced from pyrometallurgical processing is laden with sulfur dioxide (SO2). Production of sulfuric acid (H2SO4), from off-gas laden with SO2 is one of the methods used at smelters to reduce the amount of SO2 being released into the atmosphere. The acid plant consists mainly of a catalytic converter, absorption towers and a network of heat exchangers. SO2 is converted to sulfur trioxide (SO3) which is absorbed to produce a sulfuric acid product. Efficient oxidation of SO2 occurs within a tight temperature range so heat exchangers equipped with bypass valves are used to regulate the temperature throughout the acid plant. In this dissertation, a steady-state model is developed from fundamental steady-state mass and energy balances. The steady-state model provides a relation between the process variables and the temperature of the outlet streams of the heat exchangers. Unknown variables are estimated using industrial operating data. The steady-state model is used to investigate the effect of process variables on the controlled variables. The disturbance variables that have the largest effect on the process are the feed gas flow rate and the SO2 concentration. The results provide useful information since with recent process modifications that are part of the Clean AER project, variations in the feed gas flow rate and SO2 concentration will increase. The effects of the manipulated variables were also investigated which provides a foundation of understanding for process control. The results of the investigation of the effect of process variables on the controlled variables were quantified by calculating the steady-state gains. The dynamics of the process were investigated through analyzing the industrial operating data. The output variables do not va