Influence of fracture roughness and micro-fracturing on the mechanical response of rock joints: a discrete element approach

The closure and shear behaviors of 3D self-affine rock joints are simulated by the Discrete Element Method using PFC3D. First, a methodology to produce rough self-affine rock joints using DEM is presented then eight self-affine rough joints, having low and high values of roughness exponent, self-affine correlation length, and height variance, are considered. After the calibration of the elastic and fracture behaviors of an elementary volume formed from spherical discrete elements bonded by elastic beams, the numerical rock joints are submitted to closure tests at 14 and 21 MPa followed by a shear test at constant velocity and under constant normal load. Each DEM joint is tested using three different mechanical models: rigid, ideally elastic and elastic-fracturing. The use of these three models allows highlighting the distinct influences of the morphology, the joint stiffness and the micro-fracturing on the closure and shear behaviors of the joints.     

A circular economy and industrial ecology toolbox for developing an eco-industrial park: perspectives from French policy

Clean Technologies and Environmental Policy - The twentieth century was characterized by an increase in research studies concerning the interactions between economic system growth and environmental...     

Survival kinetics of Ephestia kuehniella eggs during 46–75 °C heat treatment

The effect of heat treatment on the survival of Ephestia kuehniella eggs was examined. Samples of 60 eggs were immersed in hot water at constant temperature in the 46–75 °C range for 5–1200 s. Following heat treatment and cooling, the eggs were stored at 24 ± 1 °C in a growth chamber for 7 days before survival evaluation. Statistical analysis of the data demonstrated that the thermal survival kinetics were best represented by a first-order reaction. The rate constant had an Arrhenius-type dependence over the 54–75 °C temperature range. Kinetic parameters were estimated by non-linear regression. The activation energy (E_a) and rate constant (k_ref) at the reference temperature (T_ref = 64.8 °C), were determined as 102.2 ± 6.2 kJ mol⁻¹ and 0.061 ± 0.003 s⁻¹, respectively, over the 54–75 °C temperature range. A 0.01% survival rate was obtained after 50 s at 75 °C. The data at temperatures below 50 °C were not in accordance with those at higher temperatures. Above this temperature, mortality was likely due to physiological disorders, as noted on a DSC thermogram.     

Chemical analysis and sensory evaluation of mahi-mahi (Cryphaena hippurus) during chilled storage

Biogenic amines, total volatile base-nitrogen (TVB-N), and sensory evaluation are some of the indicators used for fish quality determination. Our objective was to evaluate the relationship among histamine, cadaverine, putrescine, TVB-N, and sensory evaluation as quality assessment tools. Two groups of six mahi-mahi fillets were refrigerated at 7 degrees C and sampled on days 0, 2, 4, 6, 8, and 10. On day 3, histamine, cadaverine, and putrescine levels reached 5, 3, and 0.5 mg/100 g, respectively, whereas TVB-N reached 30 mg/100 g. Sensory scores were 6 to 6.5 (10 very fresh and 1 very spoiled) for odor, appearance, texture, and color. Correlations were 0.78 and 0.72 between histamine and cadaverine and histamine and putrescine, 0.74 and 0.80 between TVB-N and cadaverine and TVB-N and putrescine, and 0.75 and 0.78 between odor and putrescine and odor and cadaverine. AromaMaps showed distinct trends for deteriorating mahi-mahi (Coryphaena hippurus) quality.     

Effects of temperature and pH on the kinetics of caramelisation,protein cross-linking and Maillard reactions in aqueous model systems

Solutions of either glucose, bovine serum albumin (BSA), casein, glucose–BSA or glucose–casein were heated at 60 to 100 °C at pH 8.0 and pH 9.7, and the kinetics of the reaction markers (disappearance of the glucose and amino groups, development of UV absorbance and browning, and protein reticulation) were monitored. All the markers were enhanced at increasing temperatures, and, except for the disappearance of the free amino group and protein polymerisation, at alkaline pH levels. The loss of the amino group occurred in parallel with increase in polymerisation. The two proteins reacted in line with their amino content and solubility. The activation energy (E_a) of the amino group loss in the protein–glucose mixture was around 100 kJ per mol and that in the protein heated alone was higher. The E_a associated with the disappearance of glucose was around 90 kJ per mol. The E_a of UV absorbance and browning processes, which showed parallel time courses, were found to range from 90 to 150 kJ per mol.     

Surface densification of porous ZrC by a laser process

Thin films of 100%-dense zirconium carbide, ZrC, on top of ca. 30%-porous ZrC are obtained by using an ytterbium-doped fibre laser under argon atmosphere. It is shown experimentally and theoretically that oxidation into zirconia or oxycarbide is completely avoided at the working temperature of at least 3420 °C. This type of highly refractory materials – dense at the surface and porous in the bulk – could be used in high temperature applications where both diffusion and thermal barrier properties are needed. This process could also be used to purify from oxygen the surface of carbides obtained by thermal carboreduction of oxides.     

A multiple scattering algorithm for atmospheric correction of remotely sensed ocean colour (MERIS instrument): Principle and implementation for atmospheres carrying various aerosols including absorbing ones

A multiple scattering algorithm for atmospheric correction of satellite ocean colour observations is described. This algorithm, precisely designed for the MERIS instrument, globally assesses the combined contributions of aerosols and molecules to the multiple scattering regime. The approach was introduced in a previous work, where it was shown that, for a given aerosol, multiple scattering effects can be assessed through the relationship between the aerosol optical thickness and the relative increase in the path radiance that results from the progressive introduction of this aerosol within an aerosol-free atmosphere. Based on considerations about the accuracy to which the water-leaving radiances should be retrieved, the need to account for multiple scattering is argued. The principle of the algorithm is then presented, and tests and sensitivity studies (especially as regards aerosol type and vertical distribution) are performed to assess its performance in terms of errors on the retrieved water-leaving reflectances and pigment concentrations. The algorithm is able to perform the correction for atmospheres carrying several aerosol types, including absorbing ones, through their identification in the near-infrared, and through the detection of their absorption by means of appropriate assumptions on the marine signals at 510 and 705nm.     

Flow Patterns and Heat Transfer in a Cylindrical Annulus under 1g and low-g Conditions: Theory and Simulation

A dielectric fluid is confined in a stationary vertical cylindrical annulus. A temperature difference is applied between the two cylinders, as well as an alternating electric potential. This configuration creates an active force called dielectrophoretic force, which acts as a thermal buoyancy force. Different axial gravity intensities are considered, so that two thermal buoyancies will affect the flow: the thermoelectric buoyancy intervenes in the radial direction and the Archimedean buoyancy acts in the axial direction. Linear stability analysis and direct numerical simulation are performed following experimental research that has been performed during parabolic flight campaigns.