Fuzzy Tree Clustering Algorithm with Mobile Data Collectors in Wireless Sensor Networks

In recent years, the need to deploy Wireless Sensor Networks increases in different applications. Several studies have been proposed to demonstrate the importance to use Mobile Data Collectors (MDC) in Wireless sensor Networks. The main goal of this paper is to reduce the energy consumption of sensor nodes and to extend the network lifetime. In this paper, we propose to construct a Minimum Spanning tree, we design a fuzzy Cluster Head election system to elect the best sensor nodes as Cluster Heads, considering two input parameters, namely the weight of Sensor Nodes (WoSN) and the State of Sensor Node Locations (SoSNLoc). To extend the network lifetime, a subset of MDCs travels the area to gather the sensed data from nodes instead of sending them directly to the Base Station (BS) in a single hop or multi-hop manner. The BS is located at the center of the area which will be divided into sub-regions, one for each MDC. According to their positions, each CH will belong to a specific region, and then will be visited by the corresponding MDC. Simulation results show the effectiveness of our proposed algorithm in terms of energy consumption and network lifetime in comparison with other ones.

     

Ébullition par Convection Forcée des Mélanges Eau‐Ammoniac dans un Tube Vertical

An experimental study has been conducted on the forced convective boiling heat transfer of ammonia‐water mixtures flowing inside a 6 mm inner diameter vertical smooth tube. Using a water‐heated double pipe type generator, the local heat transfer coefficients are measured inside the inner tube for a range of heat flux density (29.93 — 99.79 kW/m²), mass flux density (35.36 — 99.04 kg/m²·s), mass flow rate (0.001 — 0.03 kg/s) and ammonia mass concentration (49%, 55% and 61%). The effect of the experimental parameters on the heat transfer coefficients is analysed. Three methods are used to predict the boiling heat transfer coefficients. Experimental data were compared with the available correlations. The obtained results confirm the good performance of the Mishra et al. (1981) and Bennett‐Chen's (1980) correlations in predicting the convective boiling heat transfer coefficient of NH₃‐H₂O mixtures. These methods are able to predict the boiling heat transfer data within an average accuracy of ± 20 %.     

Crystallographic Orientation in Pure and Aluminum-Doped Zinc Oxide Thin Films Prepared by Sol–Gel Technique

Novel sol–gel processes for the preparation of grain-oriented thin films of pure and aluminum-doped zinc oxide (AZO) are reported. Using various stabilizing ligands, oxide films with different degree of c -axis orientation could be prepared on amorphous substrates. The origin of orientation in sol–gel-derived ZnO and AZO films is investigated. The texture selection of ZnO films is independent of the heat-treatment schedule but sensitive to the precursor system. The electrical properties of the films do not depend significantly on the crystallographic orientation. The film visible transmittance remained higher than 90% even after vacuum annealing.     

Kinetics of tungsten‐catalyzed sunflower oil epoxidation studied by 1H NMR

Sunflower oil (SO) is a renewable resource that can be epoxidized, and the epoxidized SO has potential uses as an environmentally friendly and reactive material in polymeric formulations, especially for polyvinyl chloride. SO was epoxidized with peracetic acid, which was either preformed or prepared in situ. In order to optimize the formation of oxirane rings, the epoxidation and the extent of the side reactions were studied at different temperatures. The peracetic acid was obtained by acidic catalysis in the presence of a cation‐exchange resin. The optimum conversions were obtained within a 4‐h reaction period at 55 °C by the in situ epoxidation technique. The epoxidation was also carried out with hydrogen peroxide in the presence of peroxotungstic acid complexed with lipophilic phosphorus‐based ligands. ¹H NMR was used to define the new indices Δ and Ω, which are the mean numbers of C=C double bonds and oxirane rings per fatty acid chain, respectively. This allowed monitoring of the reaction and quantification of the results. Peroxotungstic catalysts appeared less performing than peracids in the epoxidation of SO, but were found very efficient for the epoxidation of the SO methyl esters.     

Effects of eccentricity defect on the nonlinear dynamic behavior of the mechanism clutch-helical two stage gear

This paper investigates the nonlinear dynamic behavior of an automotive clutch coupled with a helical two stage gear system. The nonlinear dynamic model is simulated by twenty seven degrees of freedom and including three types of nonlinearity: dry friction path, double stage stiffness and spline clearance. The utility of the proposed nonlinear model is illustrated by the industrial need to clearly identify the dynamic behavior of mechanical elements (shafts, bearings, gears, flywheel, pressure plate, hub of the clutch…) and reduce vibration. The governing nonlinear time varying motion equation formulated is resolved by the analytic Runge Kutta method.Then the modeling of the eccentricity defect located on the gear and the flywheel of the clutch is done. The effect of this defect on the nonlinear dynamic behavior of the system is investigated.     

Shaft misalignment effect on bearings dynamical behavior

The inherent problems of the rotating machine dysfunction are often caused by shaft misalignment. This defect generates some important loads and vibrations, and can lead to a premature failure of the bearing, the shaft, or the coupling. This work deals with the development of a theoretical model describing this phenomenon. This allows obtaining and analysing the vibration response as well as the reaction in bearings.     

Re-examination of the β→γ transformation of Ca2SiO4

Dicalcium silicate finds applications in different fields (cement, bio-ceramics, refractories). In the case of Portland cement, its interest is its lower sintering temperature compared to tricalcium silicate and therefore an interesting compound for low CO₂ cements. Dicalcium silicate goes through different polymorphic forms, namely α, α'_H, α'_L, β and γ, as the temperature decreases. In theory, only the γ-phase is stable at room temperature. In a polycrystalline material, the different polymorphs can co-exist depending on several factors (sintering conditions, presence of impurities, grain size) and the interpretations given in the literature are sometimes contradictory. For cement applications, only the α, α' or β polymorphs react with water to give hydrates while γ does not. Therefore, this paper focuses specifically on the effect of grain size on the β to γ transformation. We also propose that the transformation is semi-reconstructive and not martensitic as suggested by some authors.     

Erratum to: An improved multimodal signal-image compression scheme with application to natural images and biomedical data

Multimedia Tools and Applications -     

Shaft misalignment effect on bearings dynamical behavior

The inherent problems of the rotating machine dysfunction are often caused by shaft misalignment. This defect generates some important loads and vibrations, and can lead to a premature failure of the bearing, the shaft, or the coupling. This work deals with the development of a theoretical model describing this phenomenon. This allows obtaining and analysing the vibration response as well as the reaction in bearings.