The mini-conical slump flow test: Analysis and numerical study

This paper provides a general study on cement paste flow. Both mini-slump and Marsh cone tests are used to evaluate the workability of fresh paste mixtures derived from self compacting concretes. A numerical approach is used to reproduce global flow behavior and to check the accuracy of the obtained viscosity as well as the validity of expressions available in the literature giving yield stress from the final diameter of slumped paste. The computational modeling allows access to local information in order to analyze different regions and corresponding flow types, i.e. falling solid and flowing fresh cementing material mixtures.The limitation of some empirical models allowing the prediction of yield stress τ₀ and plastic viscosity μ from mini-slump tests is underlined, conditions of validity are expressed and a new expression is proposed.     

The influence of cyclic deformation on the strength and elongation at break of carded and combed wool yarns

There are various factors that influence yarn strength. Yarn breaking is due to fiber breakages and fiber’s slippages. In reality, a part of the fibers slip while the other part breaks. In this study, we have shown that fatigue yarn, resulting in a fundamental way impact on the number of breaks on the weaving machine, and sometimes on the physical properties of fabrics. Given the importance of the issue and the very limited directed research number in this direction, a tests series were carried out with the aim to highlight the changes to the physical characteristics of the yarn resulting from mechanical treatment comparable to that which they are subjected on the weaving machine. In the first part of our investigation, the residual deformation, tensile strength, and elongation at break of combed and carded threads were measured. In the second part, the influence of the extensions number, their amplitudes, and frequencies were analyzed. In order to examine the influence of these parameters, carded and combed yarns, with different characteristics were prepared. Therefore, based on the separate treatment results of three test series, it appears that: the warp yarns subjected to repeated extensions undergo the phenomenon of fatigue. Yarns fatigue reduces their elasticity and resistance and it is the cause for break yarn during weaving. The fatigue of wool yarns is very low compared to other textile materials.     

Mercury and methylmercury concentrations in high altitude lakes and fish (Arctic charr) from the French Alps related to watershed characteristics

Total mercury (THg) and methylmercury (MeHg) concentrations were measured in the muscle of Arctic charr (Salvelinus alpinus) and in the water column of 4 lakes that are located in the French Alps. Watershed characteristics were determined (6 coverage classes) for each lake in order to evaluate the influence of watershed composition on mercury and methylmercury concentrations in fish muscle and in the water column. THg and MeHg concentrations in surface water were relatively low and similar among lakes and watershed characteristics play a major role in determining water column Hg and MeHg levels. THg muscle concentrations for fish with either a standardized length of 220 mm, a standardized age of 5 years or for individualuals did not exceed the 0.5 mg kg^− 1 fish consumption advisory limit established for Hg by the World Health Organization (WHO, 1990). These relatively low THg concentrations can be explained by watershed characteristics, which lead to short Hg residence time in the water column, and also by the short trophic chain that is characteristic of mountain lakes. Growth rate did not seem to influence THg concentrations in fish muscles of these lakes and we observed no relationship between fish Hg concentrations and altitude. This study shows that in the French Alps, high altitude lakes have relatively low THg and MeHg concentrations in both the water column and in Arctic charr populations. Therefore, Hg does not appear to present a danger for local populations and the fishermen of these lakes.     

Annealing Temperature Effect on Bismuth Induced Crystallization of Hydrogenated Amorphous Silicon Thin Films

Silicon - In this work, we emphasis on the Bismuth induced crystallization of hydrogenated amorphous silicon (a-Si) thin films. 50 nm of bismuth thin films are deposited by vapor...     

Use of Endostemon tereticaulis (Pear.) M.Ashby and Hyptis spicigera Lam. Plant Extracts as Corrosion Green Inhibitors for Mild Steel in 1M HCl: Electrochemical and Surface Morphological Studies

Protection of Metals and Physical Chemistry of Surfaces - In the present study, we evaluated the effect of corrosion inhibition of ethanol extracts from Endostemon tereticaulis and Hyptis spicigera...     

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.     

ESHARP: Energy-Efficient and Smart Hierarchical Routing Protocol Based on Smart Slumber for Wireless Sensor Networks

Wireless Personal Communications - This paper proposes a new energy management function intended to be integrated in the Hierarchical Smart Routing Protocol (HSRP) mainly proposed for Wireless...     

Numerical Investigation of Forced Convection Nonequilibrium Effects on Heat and Mass Transfer in Porous Media

A numerical investigation is performed to analyze the coupled heat and mass transfer in porous media with a strong exothermic reaction. Similar problems have received great attention due to their relevance in a wide variety of engineering applications, such as heat pipes, drying technologies, nuclear reactors, catalytic reactors, environmentally clean utilization of energy, and many others. The momentum transfer in the porous substrate is modeled with the Darcy–Brinkman–Forchheimer law, while the temperature and concentration fields are obtained subsequently from the energy and diffusion equations. The considered configuration consists of a cylindrical duct where a first-order reaction is supposed to occur. The governing equations are solved by using the finite-volume method. The SIMPLER algorithm is applied to solve the momentum and continuity equations. The power-law scheme is used to model the interaction between convection and diffusion terms. The effect of the main governing parameters, such as permeability, aspect ratio, solid-to-fluid conductivity ratio, Reynolds number, Biot number, and the modified Frank-Kamenetskii number, are studied. The comparison with previously published work shows excellent agreement.     

RaCH: A New Radial Cluster Head Selection Algorithm for Wireless Sensor Networks

Wireless Personal Communications - This paper presents a radial cluster heads selection mechanism for homogenous wireless sensor networks. It aims to ensure a good load balancing and enhance the...     

Regularization, Scale-Space, and Edge Detection Filters

Computational vision often needs to deal with derivatives ofdigital images. Such derivatives are not intrinsic properties ofdigital data; a paradigm is required to make them well-defined.Normally, a linear filtering is applied. This can be formulated interms of scale-space, functional minimization, or edge detectionfilters. The main emphasis of this paper is to connect these theoriesin order to gain insight in their similarities and differences. We donot want, in this paper, to take part in any discussion of how edgedetection must be performed, but will only link some of the current theories. We take regularization (or functional minimization) as astarting point, and show that it boils down to Gaussian scale-space ifwe require scale invariance and a semi-group constraint to besatisfied. This regularization implies the minimization of afunctional containing terms up to infinite order of differentiation.If the functional is truncated at second order, the Canny-Deriche filter arises. It is also shown that higher dimensional regularizationboils down to a rotated version of the one dimensional case, whenCartesian invariance is imposed and the image is vanishing at theborders. This means that the results from 1D regularization can beeasily generalized to higher dimensions. Finally we show how anefficient implementation of regularization of order n can be made byrecursive filtering using 2n multiplications and additions peroutput element without introducing any approximation.