Pistacia lentiscus extract as a green inhibitor for copper corrosion in 0.5 M of H2SO4: electrochemical characterization and theoretical investigations

Journal of Applied Electrochemistry - The current work aims to study the effect of Pistacia lentiscus (Pil) essential oil originating from Chefchaouen city, which is located in northeastern Morocco...     

Measured infrared optical cross sections for a variety of chemical and biological aerosol simulants

We conducted a series of spectral extinction measurements on a variety of aerosolized chemical and biological simulants over the spectral range 3-13 microm using conventional Fourier-transform IR (FTIR) aerosol spectroscopy. Samples consist of both aerosolized particulates and atomized liquids. Materials considered include Bacillus subtilis endospores, lyophilized ovalbumin, polyethylene glycol, dimethicone (SF-96), and three common background materials: kaolin clay (hydrated aluminum silicate), Arizona road dust (primarily SiO2), and diesel soot. Aerosol size distributions and mass density were measured simultaneously with the FTIR spectra. As a result, all optical parameters presented here are mass normalized, i.e., in square meters per gram. In an effort to establish the utility of using Mie theory to predict such parameters, we conducted a series of calculations. For materials in which the complex indices of refraction are known, e.g., silicone oil (SF-96) and kaolin, measured size distributions were convolved with Mie theory and the resultant spectral extinction calculated. Where there was good agreement between measured and calculated extinction spectra, absorption, total scattering, and backscatter were also calculated.     

A new IMM algorithm using fixed coefficients filters (fastIMM)

In this paper we present an new approach based on two filters αβ$\alpha \beta$ and αβγ$\alpha \beta \gamma$ using Interacting Multiples Models (IMM) design instead of a Kalman filter second and third order for the tracking a single maneuver target. The comparison between the proposed filter and the IMM improves the computing time amount about 60% while having a high accuracy.     

Mechanical stresses and crack analysis of concrete under the hygrothermic effect

The hygrothermal process can change the porosity and the permeability of concrete, causing the initiation and the growth of the cracks, and thus deteriorating the integrity of the concrete structure. A numerical formulation based on the finite element method is developed to carry out the simulation of the initiation and the propagation of the cracks caused by the coupled field of thermal transfer and moisture transport. An original concept based on three-dimensional stress state of the integration points in each finite element is described. The global relative crack density is used to denote the cracking state of the entire concrete structure, which may serve as an appropriate index to evaluate the overall deterioration level of the structure.     

In situ measurement of the infrared absorption and extinction of chemical and biologically derived aerosols using flow-through photoacoustics

In an effort to establish a more reliable set of optical cross sections for a variety of chemical and biological aerosol simulants, we have developed a flow-through photoacoustic system that is capable of measuring absolute, mass-normalized extinction and absorption cross sections. By employing a flow-through design we avoid issues associated with closed aerosol photoacoustic systems and improve sensitivity. Although the results shown here were obtained for the tunable CO2 laser waveband region, i.e., 9.20-10.80 microm, application to other wavelengths is easily achievable. The aerosols considered are categorized as biological, chemical, and inorganic in origin, i.e., Bacillus atrophaeus endospores, dimethicone silicone oil (SF-96 grade 50), and kaolin clay powder (alumina and silicate), respectively. Results compare well with spectral extinction measured previously by Fourier-transform infrared spectroscopy. Comparisons with Mie theory calculations based on previously published complex indices of refraction and measured size distributions are also presented.     

MEMS multi-vibrating ring gyroscope for space applications

Microsystem Technologies - This paper presents the design of a novel multi-ring vibratory gyroscope. The design incorporates two sets of rings, inner and outer, separated by a set of perforated...     

Crack arrest and stress dependence of laser-induced surface damage in fused-silica and borosilicate glass

Results of experiments on stress-inhibited laser-driven crack growth and stress-delayed laser-damage initiation thresholds in fused silica, borosilicate glass (BK-7), and cleaved bulk silica are presented. A numerical model is developed to explain the crack arrest in fused silica. Good agreement is obtained between the model and a finite-element code. The crack arrest is demonstrated to be the result of the breaking of a hoop-stress symmetry that is responsible for crack propagation in fused silica.     

Iterative approaches for solving a multi-objective 2-dimensional vector packing problem

In this paper, we address a bi-objective 2-dimensional vector packing problem (Mo2-DBPP) that calls for packing a set of items, each having two sizes in two independent dimensions, say, a weight and a height, into the minimum number of bins. The weight corresponds to a “hard” constraint that cannot be violated while the height is a “soft” constraint. The objective is to find a trade-off between the number of bins and the maximum height of a bin. This problem has various real-world applications (computer science, production planning and logistics). Based on the special structure of its Pareto front, we propose two iterative resolution approaches for solving the Mo2-DBPP. In each approach, we use several lower bounds, heuristics and metaheuristics. Computational experiments are performed on benchmarks inspired from the literature to compare the effectiveness of the two approaches.     

Improvements of the reactivity devices modeling for the advanced CANDU reactor

In the context of the ACR™ (Advanced CANDU Reactor), 3D transport calculations are required in order to simulate the reactivity devices located perpendicularly to the fuel channels. The computational scheme that is usually used for CANDU-6 and ACR reactors is based on a simplified supercell geometry in which the fuel clusters and devices are replaced by annuli. Recently, an exact modeling of 3D supercell configurations was introduced within the framework of the ACR calculations. However, with such a model, fine meshing requirements lead to problems that are very demanding in terms of computational resources.

In this paper, we present improvements introduced in the ACR context to reduce the cost of the 3D supercell calculations. Two avenues of investigations are reported. First, the introduction of an accelerated characteristics method permits to reduce the computational burden of such calculations involving a large number of regions. In addition, contrarily to CANDU-6 supercell configurations, the ACR 3D geometry is prismatic and consequently a special tracking procedure can be used. This approach introduces no approximation and is significantly faster than the general 3D tracking technique. Thanks to these modifications in the computational procedure, 3D supercell calculations with a level of mesh discretization comparable to 2D cell configurations become affordable for industrial applications.