Solid transport in a pyrolysis pilot-scale rotary kiln: preliminary results - stationary and dynamic results

4th International Conference on Conveying and Handling of Particulate Solids, Budapest, HUNGARY, MAY 27-30, 2003International audienceExperiments for the investigation of the flow of granular solids in a pyrolysis pilot-scale rotary kiln are presented. These experiments consisted first in measuring the volumetric filling ratio (steady-state experiences) for several operating conditions and second in recording the exit flow rates after a positive or negative step in one of the operating parameters (dynamic experiences). A dynamical model computing the evolution of the flow rate of granular solids through the kiln has been developed based on Saeman model [Chem. Eng. Prog. 47 (1951) 508]. The simulations are compared with experimental results; the model gives good results for the rolling mode, but for the slipping mode too

Seasonal, monthly and weekly variation of suicide in Pietermaritzburg and the relationship between suicide and meteorological factors.

Thesis (M.Soc.Sc.)-University of Natal, Pietermaritzburg, 2000.This study investigated the seasonal, monthly and weekly variation of fatal suicidal behaviour in Pietermaritzburg, as well as the relationship between fatal suicidal behaviour and climate. Secondary analysis was performed on suicide data collected for two unpublished honours theses. Results indicate that there is significant monthly variation in the distribution of fatal suicidal behaviour in Pietermaritzburg, with the expected spring-summer peak and winter trough . This pattern was more pronounced for adults than for the youth or the elderly. There was no significant variation in the weekly distribution of suicide, and suicides did not reach a peak on Monday as has been evidenced in previous research. Instead, the distribution showed a peak on Sunday with a steady decrease towards the end of the week. An increase in humidity, ambient temperature and minimum temperature was associated with an increase in suicide rates . Overall this relationship was stronger for violent, than non-violent suicide. However, a significant negative relationship was found between hours of sunshine and suicide, but this was only significant for non-violent suicide. This study was largely descriptive, and further research is indicated in order to develop a theoretical framework for understanding the temporal distribution of suicide

Un attractif sexuel pour la tordeuse des bourgeons : Archips xylosteana L. (Lepid., Tortricidae, Tortricinae)

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Evolution of defects in Ti6-4 under Ti2+ ion irradiation: Focus on radiation-induced precipitates

Ion irradiations on the Ti6-4 titanium alloy were conducted at the JANNUS French platform in two different conditions of temperatures, doses and fluxes, to simulate neutron irradiation damage. Quantification of defects and chemical microanalyses were carried out thanks to Transmission Electron Microscopy and Atom Probe Tomography. -type loops and radiation induced precipitates (a vanadium-rich β BCC phase) were observed for both irradiation temperatures. During an irradiation at 300 °C, there was no notable influence of the dose and flux for the considered doses and fluxes ranges on the -type defects. The influence of raising the irradiation temperature up to 430 °C was a lowering of their density and an increase of their mean diameter for both defects. In addition, a lower flux seemed to enhance this temperature effect. These phenomena were very significant for precipitates whereas it appeared very modest for -type loops. The probable mechanism to explain the distribution of vanadium-rich β precipitates inside the α phase is the heterogeneous nucleation. The nucleation is dominated by the Radiation Induced Segregation (RIS) phenomenon at 430 °C and could be dominated by the mechanism of vanadium-rich clusters formation by ballistic effects in the cascades at 300 °C

Optimization methodology for high COD nutrient-limited wastewaters treatment using BAS process

Optimization of biofilm activated sludge (BAS) process via mathematical modelling is an entangle activity since economic, environmental objective and technical decision must be considered. This paper presents a methodology to optimize the operational conditions of BAS process in four steps by combining dynamic simulation techniques with non-linear optimization methods and with operative decision-making criteria. Two set of variables are separately prioritized in the methodology: essential variables related to physical operation to enforce established process performance, and refinement variables related to biological processes that can generate risks of bulking, pin-point floc and rising sludge. The proposed optimization strategy is applied for the treatment of high COD wastewater under nutrient limitation using an integrated mathematical model for COD removal that include predation, hydrolysis and a simplified approach to the limiting solids flux theory in the secondary clarifier in order to facilitate the convergence of the optimization solver. The methodology is implemented in a full-scale wastewater treatment plant for a cellulose and viscose fibre mill obtaining (i) improvement of the effluent quality index (Kg pollution/m3) up to 62% and, (ii) decrease the operating cost index (€/m3) of the process up to 30% respect the regular working operational conditions of the plant. The proposed procedure can be also applied to other biological treatments treating high COD nutrient-limited industrial wastewater such as from textile and winery production among others