An approach for the integration of swarm intelligence in MAS: An engineering perspective

For more than 20 years, researchers have designed models in order to describe swarm intelligence and apply the resulting techniques to complex problems. However, there is still a gap between these models and current MAS methodologies. The goal of this paper is to propose a principled and methodological approach for the engineering of systems based upon swarm intelligence. The constraints are, on the one hand, to enable the analysis, design and implementation of such systems; and, on the other hand, to formally analyze and verify properties of resulting systems. The principles of the approach are based, on the one hand, on requirement driven activities that produce goals to be fulfilled by the system of interest and, on the other, hand on an ontological modeling of the problem domain. This ontological modeling conceptualizes the phenomenon one seek to imitate and thus allows it understanding. The produced ontology is refined through the methodology activities down to organizational models.     

Experimental Study of Particle Losses Close to the Entry of Thin-Walled Sampling Probes at Varying Angles to the Wind

This article summarizes the results of an extensive experimental study of sampling losses in thin-walled probes at various values of velocity ratio R and the probe orientation with respect to the freestream. The purpose of this study was to gain insights into the complex interaction of various parameters that influence sampling losses and the consequent effect on the overall sampling efficiency. A 0.635 cm diameter sharp-edged tube was mounted in a small wind tunnel where the freestream velocity could be varied over a wide range of values. Polydispersed spherical glass beads were used as the test aerosol. The number concentration and the particle size distribution were measured using the aerodynamic particle sizer (APS 3310). The sampling efficiency was determined as a function of orientation for a range of particle sizes (or Stokes number). By using an existing model to predict the aspiration efficiency for thin-walled probes, the sampling losses could be isolated from the sampling efficiency. In this manner a new empirical model was developed to predict the losses as a complex function of Stokes number, sampler orientation, and velocity ratio. The losses appear to be influenced by particle inertia, impaction, gravitational settling in the boundary layer developing inside the thin-walled probe, and vena contracta or flow recirculation loss near the entry. It was evident from the results that these losses are strongly influenced by the Stokes number and sampler orientation. The losses also increased strongly with increasing value of velocity ratio for all orientations.     

Modelling the influence of human behaviour on the spread of infectious diseases: a review

Human behaviour plays an important role in the spread of infectious diseases, and understanding the influence of behaviour on the spread of diseases can be key to improving control efforts. While behavioural responses to the spread of a disease have often been reported anecdotally, there has been relatively little systematic investigation into how behavioural changes can affect disease dynamics. Mathematical models for the spread of infectious diseases are an important tool for investigating and quantifying such effects, not least because the spread of a disease among humans is not amenable to direct experimental study. Here, we review recent efforts to incorporate human behaviour into disease models, and propose that such models can be broadly classified according to the type and source of information which individuals are assumed to base their behaviour on, and according to the assumed effects of such behaviour. We highlight recent advances as well as gaps in our understanding of the interplay between infectious disease dynamics and human behaviour, and suggest what kind of data taking efforts would be helpful in filling these gaps.     

CONTROL OF COKE FORMATION FROM HYDROCRACKED ATHABASCA BITUMEN

ABSTRACT

The mechanism of formation of carbonaceous deposits from hydrocracked Athabaca bitumen is shown to result in both isotropic and anisotropic solids. The formation of mesophase spheres present as a separate liquid phase has been observed in the laboratory High severity results in the formation of an increased amount of anisotropic solid which is observed in both laboratory and commercial samples. The formation of these deposits in the downstream separators of a commercial plant has occurred and is a hindrance to reliable operation. A strategy to reduce the formation of these deposits in a commercial plant was evaluated in a series of laboratory experiments. The use of process-derived gas oils can be used as quench oil to lower the temperature of the commercial separators. There was no increase in the rate of toluene insoluble formation as a result of the use of quench oils, which allowed the full advantage of the temperature decrease to be achieved. A qualitative comparison of the build-up of deposits in the commercial separators is provided from separator vessel monitoring.     

Les pratiques éducatives en sciences et en technologie: Points de vue d'enseignants et d'enseignantes

Résumé:

L'enseignement des sciences et des techniques fait l'objet de préoccupations en raison de leur importance dans la formation des élèves du secondaire et de l'impact qu'elles ont sur leur orientation scolaire et socioprofessionnelle future. Les conceptions que les éducateurs entretiennent au regard des disciplines scientifiques et les pratiques qu'ils exercent influencent pour une bonne part celles des élèves ainsi que les apprentissages qu'ils font. Le présent article, qui s'inscrit dans le cadre d'une étude d'ensemble sur les représentations sociales des sciences et des technologies chez les différents acteurs éducatifs et chez les élèves du secondaire, fait état des postures spécifiques endossées par des enseignants de sciences en lien avec un tel enseignement et tente, sur la base des discours qu'ils produisent, d'en dégager les significations, les préoccupations sociales invoquées et le caractère médiateur de l'activité didactico‐pédagogique engagée nous intéressant particulièrement.     

Fugitive Methane Emissions from Landfills: Field Comparison of Five Methods on a French Landfill

The study presented in this paper has been initiated by the Veolia Environment research center for waste management and supported by the French Environmental Agency. A comparison of five field-scale measurement methods for measuring fugitive methane emissions has been conducted on a French landfill site. The five methods evaluated consisted of a tracer gas technique, laser radial plume mapping, inverse modeling technique, differential absorption light detection and ranging (LiDAR), and helicopter-borne spectroscopy. These methods are evaluated on their abilities to measure emissions from a practical user-oriented aspect (metrological, technical, and economical criteria). High disparities in terms of quantitative results and applicability were observed from all methods. Techniques that used Gaussian dispersion modeling appeared less applicable to landfill sites due to topographic complexity and did not provide high confidence in the results. However, the method using optical remote sensing (radial plume mapping) methods showed that a spatially detailed analysis is achievable (cell level), and the LiDAR method showed very promising approach and technical performances.     

DC pulsed plasma deposition of nanocomposite coatings for improved tribology of gray cast iron stamping dies

Automotive stamping dies are very large in size with sizes ranging up to 2 m × 2 m × 1 m. The primary material used in the manufacturing of these dies is gray cast iron that is relatively cheap with good castability, machinability and reparability. Due to its lack of adequate hardness, die wear is a major problem at highly loaded die features such as corners, bead-radii, punch-radii etc. The greater is this wear, the greater is the die-related down times and production losses. This problem of die wear has become even more significant in recent times due to the introduction of Advanced High Strength Steels (AHSS) and Ultra High Strength Steels (UHSS) in automotive stamping. Stamping of these materials is accompanied by higher contact pressures on the die surface, higher abrasion and higher surface temperature from frictional heat.This paper presents a novel DC pulsed plasma based approach to the deposition of triplex coating on cast iron substrates that can withstand high normal pressures, shears, sliding and abrasion experienced during stamping. This triplex coating consists of silicon enhanced nanocomposite a-C:H film supported by plasma nitrocarburized duplex case. This nanostructured-composite film is shown to have high toughness and extremely low coefficients of friction. A unique feature of this plasma processing is the industrial size of chambers used in the coating development. This paper also includes results of film characterization and its performance evaluation in simulated wear tests that generate stresses similar to actual stamping dies. By carefully designing the plasma processing treatment, a good hardness gradient and elastic modulus gradient is achieved that provide an improvement in life of about 5 times that of the currently used hard chrome plating.     

Effect of annealing temperature on phase composition and tensile properties in isotactic poly(1‐butene)

The influence of annealing temperature on the kinetics of polymorphic changes and mechanical properties within the time in isotactic poly(1‐butene) (PB‐1) has been investigated by wide‐angle X‐ray scattering and tensile testing. Extruded tapes of PB‐1 have been exposed to several annealing temperatures: ?22, +5, +22, +40 and +60°C. The evolution of content of Phase I for various annealing temperatures upon time shows predominantly S‐shaped trend. Annealing temperature considerably affects the overall rate of transformation in PB‐1. On the other hand, the resulting mechanical properties are solely controlled by the polymorphic composition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012