Degradation of recalcitrant organic contaminants by solar photocatalysis.

Biological pre-treated landfill leachates of Djebel Chakir contains some macromolecular organic substances that are resistant to biological degradation. The aim of the present work is to assess the feasibility of removing refractory organic pollutants in biological pre-treated landfill leachate by solar photocatalyse process. Leachate pollutant contents are studied to assess their contribution to leachate pollution and their treatability by solar photocatalyse process. Phenol is chosen as model of pollutants, to evaluate its removal and the efficiency of the photocatalytic system. The experiments were carried out in suspended photocatalytic reactor, using TiO2 Degussa P25, under sunlight illumination (UV-A: 15-31 W/cm2). Under optimum operational conditions, applied to single reactant (phenol), the system presents a TOC removal of 90% (the degradation follows a first-order kinetic). Based on the TOC removal, the results shows that the degradation of biological pre-treated leachate follows a zero-order kinetic. After 5 h of sunlight exposure, 74% of COT is removed. The TOC removal is the best without any correction of the pH and at the TiO2 concentration of 2.5 g/L. The photocatalytic degradation of organic contaminants as well as the formation and disappearance of the by-products were followed by GC/MS. The solar photocatalysis processes induce several modifications of the matrix leading to more biodegradable forms: all the remaining and new compounds generated after the biological pre-treatment of leachate are degraded and other types of organics appear, mainly carboxylic acid, aliphatic hydrocarbons and phtalic acids.     

Linear welding of grooved wood surfaces

Linear wood welding of grooved surfaces to ease the elimination of water vapour and to increase the welding surface was performed in this study.     

Recycled micronized polyurethane powders as active extenders of UF and PF wood panel adhesives

The addition of micronized polyurethane powders obtained from waste flexible polyurethanes to urea-formaldehyde (UF) resins and to phenol-formaldehyde (PF) resins improves markedly the performance of the panels prepared with these resins, namely plywood and particleboard. Infrared spectrophotometry (FT-IR) indicates that to some limited extent a reaction does appear to occur between micronized PUR waste powder and PF resin when the mix is cured under alkaline conditions. There appears to be no reaction at all instead between acid-setting UF resins and PUR powder. In both cases an active filler or extender effect appears to occur, otherwise the improvement in dry strength of UF–bonded joints cannot be explained. Even when reaction does evidently not occur, the addition of PUR powder improves markedly the water resistance of UF and PF resins. This active extender/filler effect is not due to any isocyanate group being re-generated on heating as both FT-IR and NMR confirm the absence of these groups.     

Enhancing water resistance of welded dowel wood joints by acetylated lignin

Low molecular mass acetylated organosolv lignin from wheat straw and from depolymerised low sulphur organosolv wood lignin have been shown to markedly improve both the water resistance and the mechanical performance of welded dowel wood joints. The acetylated oligomers distribution and extent of acetylation of the two lignins were determined by Matrix assisted laser desorption ionization-time-of-flight mass spectrometry. Extensive acetylation was confirmed by CP-MAS ¹³C NMR spectrometry. Force–displacement measurements on welded dowel joints to which acetylated wood lignins were added showed a ductile behaviour. This is due to the interpenetration of the elastic acetylated lignin network into the more rigid composite network of the welded interphase.     

Optimal sensor and path selection for target tracking in wireless sensor networks

This paper addresses target tracking in wireless sensor networks where the nonlinear observed system is assumed to progress according to a probabilistic state space model. Thus, we propose to improve the use of the quantized variational filtering by jointly selecting the optimal candidate sensor that participates in target localization and its best communication path to the cluster head. In the current work, firstly, we select the optimal sensor in order to provide the required data of the target and to balance the energy dissipation in the wireless sensor networks. This selection is also based on the local cluster node density and their transmission power. Secondly, we select the best communication path that achieves the highest signal‐to‐noise ratio at the cluster head; then, we estimate the target position using quantized variational filtering algorithm. The best communication path is designed to reduce the communication cost, which leads to a significant reduction of energy consumption and an accurate target tracking. The optimal sensor selection is based on mutual information maximization under energy constraints, which is computed by using the target position predictive distribution provided by the quantized variational filtering algorithm. The simulation results show that the proposed method outperforms the quantized variational filtering under sensing range constraint, binary variational filtering, and the centralized quantized particle filtering. Copyright © 2012 John Wiley & Sons, Ltd.     

Determining the optimum cutting direction in granite quarries through experimental studies: a case study of a granite quarry

Bulletin of Engineering Geology and the Environment - Optimization of cutting operations in quarrying and processing of building stones leads to certain reductions in operational costs. Despite the...     

Fatigue characteristics of continuous welded rails and the effect of residual stress on fatigue-ratchetting interaction

ABSTRACT

The importance of ratchetting-fatigue interaction is garnering interest due to complex failure mechanism of rail welds under cyclic loading. The objective of this paper is to investigate the fatigue characteristics of continuous welded rails (CWRs) and the effect of residual stress on fatigue-ratchetting interaction. For this purpose, UIC60 rails have been modeled using a three-dimensional finite element model, including a combination of nonlinear kinematic and isotropic hardening. In addition, the interaction between cyclic loading and the effect of residual stress on fatigue is taken into consideration. Finite element model is validated against representative experimental findings. Smith–Watson–Topper (SWT) method is utilized in order to estimate the fatigue life of rail welds under static and cyclic loading. Lower fatigue life is predicted with increasing load due to the contact between rails and wheels. Simulation results also show that failure in the form of ratchetting occurs during the 10,236th cycle, while failure corresponds to the 15,290th cycle and the 145,161st cycle based on the SWT and Coffin-Manson fatigue models, respectively. These findings suggest that investigations on ratchetting and fatigue should be carried out simultaneously to estimate the failure of the CWRs.     

Effect of Wind Flow and Solar Radiation on Functionality of Water Evaporation Suppression Monolayers

Water Resources Management - The average evaporation in Iran is 3 times higher than the world average. Applying chemical monolayers on water surfaces is one of the promising methods for suppressing...     

Investigating effects of water salinity on geotechnical properties of fine-grained soil and quartz in a sandstone case study: Ajichay project in northwest Iran

The effect of water salinity on the geotechnical properties of a CL soil and mechanical properties of a quartz sandstone has been studied using samples from the Ajichay project, located in the northwest of Iran. The purpose of this investigation is to investigate the feasibility of using saline water in processing the clay core of earthen dams in this area. One-dimensional consolidation, swelling, and uniaxial compressive strength tests were performed on the soil with distilled, half-saline, and saline water. To evaluate the effect of water salinity on the sandstones placed in the abutments of the dams, the slake durability index and uniaxial compressive strength were investigated. Results indicated that the compressibility index decreased, hydraulic conductivity decreased, and uniaxial compressive strength of the soil increased with increasing water salinity. The soil swelling percent with all three waters was less than 1 % after 24 h. However, swelling percent increased by 23 % with saline water and decreased by 32 % with half-saline water. Some damage in the rock texture such as disaggregation, weathering, and corrosion of the feldspars along with the dissolution of carbonate cement was observed in thin sections after 6 months of immersion in saline water. The strength of the sandstones exposed to saline water for 5 months decreased by between 5 and 13 %.