Search results for "Particle-size distribution"
showing 10 items of 89 documents
The Influence of Crystal Size Distributions on the Rheology of Magmas: New Insights From Analog Experiments
2017
This study examines the influence of particle size distributions on the rheology of particle suspensions by using analogue experiments with spherical glass beads in silicone oil as magma equivalent. The analyses of 274 individual particle-bearing suspensions of varying modality (uni-, bi- tri- and tetramodality), as well as of polymodal suspensions with specific defined skewness and variance, are the first data set of its kind and provide important insights in the relationship between the solid particles of a suspension and its rheological behaviour. Since the relationship between the rheology of particle bearing suspensions and its maximum packing fraction ϕm is well established by several…
Strain rate dependence for evolution of steady state grain sizes: Insights from high-strain experiments on ice
2019
Abstract Understanding of the microstructural evolution and equilibrium grain size development during steady state tertiary flow is essential in order to improve our knowledge of ice and rock deformation. This contribution presents results from in situ transmitted light deformation experiments of natural glacier ice, with the development of the microstructure in a tertiary flow regime. We conducted one relative slower ( 1 × 10 − 6 1/s) and two relative faster-strain rate ( 2 × 10 − 6 1/s) pure shear experiments at −10 °C, up to a shortening of ∼57%. Microstructure development was followed by time-lapse observations, and two new microstructure-based indicators, the ‘seeding rate’ and the ‘mi…
Ash-plume dynamics and eruption source parameters by infrasound and thermal imagery: The 2010 Eyjafjallajökull eruption
2013
During operational ash-cloud forecasting, prediction of ash concentration and total erupted mass directly depends on the determination of mass eruption rate (MER), which is typically inferred from plume height. Uncertainties for plume heights are large, especially for bent-over plumes in which the ascent dynamics are strongly affected by the surrounding wind field. Here we show how uncertainties can be reduced if MER is derived directly from geophysical observations of source dynamics. The combination of infrasound measurements and thermal camera imagery allows for the infrasonic type of source to be constrained (a dipole in this case) and for the plume exit velocity to be calculated (54–14…
Modelling of stylolite geometries and stress scaling
2012
International audience; In this contribution we present numerical simulations of stylolite growth to decipher the effects of initial rock heterogeneity and stress on their morphology. We show that stylolite growth in a rock with a uniform grain size produces different patterns than stylolite growth in a rock with a bimodal grain size distribution. Strong pinning of large heterogeneities produce stylolite structures that are dominated by pronounced teeth, whereas a uniform grain size leads to spikes and a roughness that shows variable wavelengths. We compare the simulated stylolites with natural examples and show that the model can reproduce the real structures. In addition we show that stro…
Artificial Oral Processing of Extruded Pea Flour Snacks
2021
International audience; The structure of extruded pea flour can affect chewing performances. Our objective was to relate the bolus properties (fragmentation, moisture content and viscosity) of chewed extruded pea snacks to their structure. In order to have control over oral physiological parameters, we opted for an in vitro approach using a chewing simulator, the variables of which were the flow rate of artificial salivary fluid and chewing time. The structure of the extruded pea snacks was characterized by its density and protein solubility in dithioerythritol (DTE), which reflected the amount of protein aggregates cross-linked by disulphide bonds. The particle size distribution and median…
Water retention and swelling behaviour of granular bentonites for application in Geosynthetic Clay Liner (GCL) systems
2016
Geosynthetic Clay Liner (GCL) systems are used as efficient hydraulic barriers in landfills for the disposal of hazardous municipal wastes. Along with geotextiles, bentonite materials are chosen as one of the primary components of GCLs due to their high retention, adsorption, and swelling capacities. GCLs are manufactured using bentonites at a high total suction and hydrated through the uptake of liquid from the subsoil and the confined material as soon as they are installed. Bentonites may exhibit considerable volume change upon wetting. Depending on the confinement stress, the void ratio may significantly increase with a decrease in suction, particularly at higher degrees of saturation. T…
The impact of mastication, salivation and food bolus formation on salt release during bread consumption
2014
Health authorities recommend higher fibre and lower salt content in bread products. However, these basic ingredients of bread composition are multifunctional, and important changes in their content influence the texture, flavour and acceptability of the product. This study was designed to investigate the link between oral processing, bolus formation and sodium release during the consumption of four different breads that varied in composition and structure. Chewing behaviour was determined by surface electromyography, and salivation was quantified from the water content of the boluses collected. The kinetics of bread degradation during food bolus formation was characterised by measuring the …
SW—Soil and Water
2002
Abstract Recent research has directed attention to the size distribution of eroded material because of its influence on deposition mechanics and in carrying capacity of pollutant materials. At first, in this paper the relationship between aggregate breakdown mechanism and erosion processes is briefly reviewed. Then the link between the clay enrichment ratio and the sediment delivery ratio at morphological unit scale is investigated. For 129 soil samples well distributed over the Sicilian Sparacia basin, the values for the experimental clay enrichment ratio calculated by the measured ultimate grain-size distributions are compared with the theoretical clay enrichment ratio values obtained by …
Relationship between particle size and dissolution rate of bulk powders and sieving characterized fractions of two qualities of orthoboric acid
1996
Drug Dev. Ind. Pharm. ISI Document Delivery No.: VN279 Times Cited: 1 Cited Reference Count: 22 Tromelin, A Habillon, S Andres, C Pourcelot, Y Chaillot, B; International audience; We have carried out a study of the particle size distribution and aqueous dissolution rate of two commercially available qualities of orthoboric acid, labeled ''crystal'' (ABC) and ''powder'' (ABP). In a previous work, we have shown that the two commercial qualities of orthoboric acid chosen as model compound (''powder'' and ''crystal'') are related to the same crystal network in spite of their different names. However, these two qualities have very different size particle distributions, as previously determined b…
Measurement report: Balloon-borne in situ profiling of Saharan dust over Cyprus with the UCASS optical particle counter
2021
This paper presents measurements of mineral dust concentration in the diameter range from 0.4 to 14.0 µm with a novel balloon-borne optical particle counter, the Universal Cloud and Aerosol Sounding System (UCASS). The balloon launches were coordinated with ground-based active and passive remote-sensing observations and airborne in situ measurements with a research aircraft during a Saharan dust outbreak over Cyprus from 20 to 23 April 2017. The aerosol optical depth at 500 nm reached values up to 0.5 during that event over Cyprus, and particle number concentrations were as high as 50 cm−3 for the diameter range between 0.8 and 13.9 µm. Comparisons of the total particle number concentration…