Cinétique de dégagement des matières volatiles lors de la pyrolyse d'électrodes de carbone industrielles

In aluminium plants, the anode baking process is associated with an important release of volatile combustible matter. It is the purpose of this study to investigate the kinetics of the evolution of these volatiles. A large thermogravimetry set-up has been designed in such a way that it could simulate real plant conditions. Samples of two distinct masses have been subjected to pyrolysis at different heating regimes. The loss of weight together with the concentrations of the released gases were recorded on a continuous basis during the temperature rise. Kinetic results were found for methane, hydrogen and tar. No variation of the order of reaction with the heating rate was observed, whereas the activation energy and the pre-exponential factor increased. Furthermore, for the range of sample dimensions studied, it was found that the mass of the solid had no significant influence on the kinetic parameters.     

The computational challenges of Earth-system science

The Earth system--comprising atmosphere, ocean, land, cryosphere and biosphere--is an immensely complex system, involving processes and interactions on a wide range of space- and time-scales. To understand and predict the evolution of the Earth system is one of the greatest challenges of modern science, with success likely to bring enormous societal benefits. High-performance computing, along with the wealth of new observational data, is revolutionizing our ability to simulate the Earth system with computer models that link the different components of the system together. There are, however, considerable scientific and technical challenges to be overcome. This paper will consider four of them: complexity, spatial resolution, inherent uncertainty and time-scales. Meeting these challenges requires a significant increase in the power of high-performance computers. The benefits of being able to make reliable predictions about the evolution of the Earth system should, on their own, amply repay this investment.     

Continuous recovery of acid oil

A continuous process for acidulation of all types of caustic soapstocks is described. The soap is diluted, heated, acidulated and centrifuged to yield three products: acid oil, acid water and a sludge phase. Typical performance data on various grades of soapstocks and the recovered products are given.     

Children's and adults' recognition of spontaneous and posed emotional expressions in young children.

Investigated the degree to which 4–5 yr olds (n?=?48) can enact expressions of emotion recognizable by peers and adults; the study also examined whether accuracy of recognition was a function of age and whether the expression was posed or spontaneous. Adults (n?=?103) were much more accurate than children in recognizing neutral states, slightly more accurate in recognizing happiness and anger, and equally accurate in recognizing sadness. Children's spontaneous displays of happiness were more recognizable than posed displays, but for other emotions there was no difference between the recognizability of posed and spontaneous expressions. Children were highly accurate in identifying the facial expressions of happiness, sadness, and anger displayed by their peers. Sex and ethnicity of the child whose emotion was displayed interacted to influence only adults' recognizability of anger. Results are discussed in terms of the social learning and cognitive developmental factors influencing (a) adults' and children's decoding (recognition) of emotional expressions in young children and (b) encoding (posing) of emotional expressions by young children. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Component-based end-user database design for ecologists

To solve today’s ecological problems, scientists need well documented, validated, and coherent data archives. Historically, however, ecologists have collected and stored data idiosyncratically, making data integration even among close collaborators difficult. Further, effective ecology data warehouses and subsequent data mining require that individual databases be accurately described with metadata against which the data themselves have been validated. Using database technology would make documenting data sets for archiving, integration, and data mining easier, but few ecologists have expertise to use database technology and they cannot afford to hire programmers. In this paper, we identify the benefits that would accrue from ecologists’ use of modern information technology and the obstacles that prevent that use. We describe our prototype, the Canopy DataBank, through which we aim to enable individual ecologists in the forest canopy research community to be their own database programmers. The key feature that makes this possible is domain-specific database components, which we call templates. We also show how additional tools that reuse these components, such as for visualization, could provide gains in productivity and motivate the use of new technology. Finally, we suggest ways in which communities might share database components and how components might be used to foster easier data integration to solve new ecological problems.     

A tutorial on biomedical process control

This paper presents a tutorial on five typical applications within the area of biomedical process control. The specific applications discussed include: control of insulin administration for treating diabetes mellitus, dynamic modeling for anti-cancer chemotherapy regimen design, modeling and control of drug infusion in critical care, structured treatment interruptions: a control mathematical approach to AIDS protocol design, and dynamic modeling and control of the anticoagulant drug heparin. The objective of the tutorial is to illustrate the rich and important set of problems within the biomedical area that process control engineers can contribute to solving. Solution to these problems can have a significant medical as well as economic impact.     

Parallelisation of the Lagrangian atmospheric dispersion model NAME

The NAME  Atmospheric Dispersion Model is a Lagrangian particle model used by the Met Office to predict the propagation and spread of pollutants in the atmosphere. The model is routinely used in emergency response applications, where it is important to obtain results as quickly as possible. This requirement for a short runtime and the increase in core number of commonly available CPUs, such as the Intel Xeon series, has motivated the parallelisation of NAME  in the OpenMP  shared memory framework. In this work we describe the implementation of this parallelisation strategy in NAME  and discuss the performance of the model for different setups. Due to the independence of the model particles, the parallelisation of the main compute intensive loops is relatively straightforward. The random number generator for modelling sub-grid scale turbulent motion needs to be adapted to ensure that different particles use independent sets of random numbers. We find that on Intel Xeon X5680 CPUs the model shows very good strong scaling up to 12 cores in a realistic emergency response application for predicting the dispersion of volcanic ash in the North Atlantic airspace. We implemented a mechanism for asynchronous reading of meteorological data from disk and demonstrate how this can reduce the runtime if disk access plays a significant role in a model run. To explore the performance on different chip architectures we also ported the part of the code which is used for calculating the gamma dose from a cloud of radioactive particles to a graphics processing unit (GPU) using CUDA-C. We were able to demonstrate a significant speedup of around one order of magnitude relative to the serial CPU version.     

Short communication: Identifying challenges and opportunities for improved nutrient management through the USDA's Dairy Agroecosystem Working Group

Nutrient management on US dairy farms must balance an array of priorities, some of which conflict. To illustrate nutrient management challenges and opportunities across the US dairy industry, the USDA Agricultural Research Service Dairy Agroecosystems Working Group (DAWG) modeled 8 confinement and 2 grazing operations in the 7 largest US dairy-producing states using the Integrated Farm System Model (IFSM). Opportunities existed across all of the dairies studied to increase on-farm feed production and lower purchased feed bills, most notably on large dairies (>1,000 cows) with the highest herd densities. Purchased feed accounted for 18 to 44% of large dairies' total operating costs compared with 7 to 14% on small dairies (<300 milk cows) due to lower stocking rates. For dairies with larger land bases, in addition to a reduction in environmental impact, financial incentives exist to promote prudent nutrient management practices by substituting manure nutrients or legume nutrients for purchased fertilizers. Environmental priorities varied regionally and were principally tied to facility management for dry-lot dairies of the semi-arid western United States (ammonia-N emissions), to manure handling and application for humid midwestern and eastern US dairies (nitrate-N leaching and P runoff), and pasture management for dairies with significant grazing components (nitrous oxide emissions). Many of the nutrient management challenges identified by DAWG are beyond slight modifications in management and require coordinated solutions to ensure an environmentally and economically sustainable US dairy industry.     

Electron Transfer Reactions in Pulping Systems (III): A Study of Steric Effects in Lignin Model/Aq Reactions

Abstract

The reactions of five B-aryl ether lignin model dimers with three anthrahydroquinone (AHQ) analogs have been studied. Some of the models and AHQ analogs have bulky substituents strategically located in positions which would possibly inhibit adduct reactions but not single electron transfer (SET) reactions. The fact that the model fragmentation efficiencies were the same for both steri-cally hindered and unhindered AHQ analogs indicates that the reaction mechanism cannot involve a rate determining adduct formation step. The results can be best explained either by an SET mechanism or a mechanism which involves quinoneraethide generation as a slow step, followed by adduct, SET, or other steps. Placing methyl groups on the S-carbon of the models favored model fragmentation reactions by NaOH. The B-methyl group may be promoting fragmentation reaction rates and/or retarding the rates of competing side reactions, such as vinyl ether generation.