Post-discharge plasma-chemical oxidation of Iron(II) complexes

The plasmachemical properties of an electric discharge in humid air are considered by examining the oxidation of Fe(II) to Fe(III) aquo-ions in a solution exposed to the discharge. The reaction product is characterised and quantified by means of the thiocyanate complex FeSCN²⁺. The reaction mechanism shows two distinct steps: a rapid step directly depending on the treatment time and a slow post-discharge step, which are both ascribed to species formed in the discharge (i.e., respectively to OH radical and to hydrogen peroxide or nitrate ions). These concerned species are able to react either at the liquid surface (OH) or to diffuse into the solution and react as solutes. Experimental arguments in favour of zero and first order reaction steps are given. A particular reactor design involving a multibladed electrode is tested at the juncture and its use considered for further industrial applications.     

Cyclic Filtration Apparatus for Testing Subballast under Rail Track

An apparatus capable of testing subballast-subgrade filtration behavior under cyclic loading is presented. The apparatus can be used to accurately monitor the pressure fluctuations, permeability of the filtration system, and turbidity variations of the effluent with time. The test results show that the frequency of cyclic loading has an influence on the filtration behavior of subballast material used in railway tracks. Further, the effect of cyclic load on the design and selection of subballast materials over a wet subgrade must be considered to avoid filter malfunctioning.     

Tensorial analysis of a Fourier-transform profilometric setup devoted to the evaluation of muscular contractions

We explore the potential use of the Fourier-transform profilometry technique in in vivo studies of muscular contractions through the variation of muscle-group cross sections. Thanks to a tensorial analysis of the technique, a general expression of its sensitivity vector is established. It allows derivation of the expression of the resolution and the limit condition imposed by the spatial sampling of the fringe pattern. Key parameters that maximize the sensitivity are then simulated. A measurement system is accordingly built up and characterized. It is then successfully applied to the evaluation of the deformation of the forearm muscles during grasping exertions.     

Variogram-based fault diagnosis in an interconnected tank system

We consider in this paper the fault diagnosis problem of a three tank system DTS-200 pilot plant. The presented approach is based on the analysis of the variogram, which is a graphical variance representation that characterizes the distribution of a measured dataset, and is used to extract the sensor fault parameters. These parameters are obtained by determining the best mathematical model that fits the empirical data. Nonlinear regression techniques are used to estimate the model coefficients. Experimental study is provided to illustrate the potential applicability of this method in process monitoring.     

Novel approach for replacement of a failure node in wireless sensor network

In the recent years, there has been a growing interest in wireless sensor networks (WSN). Network’s lifetime depends on energy efficiency and load balancing where connectivity is a very important factor. However, such connectivity can be lost due to the failure of some sensor nodes which creates disruptions to the network operations, lead to a reconfiguration of the network by generating energy losses, or in another case, the network mission fails. Energy conservation is a very important problem in WSN. In this paper, we propose a new solution for the connectivity problem when failure nodes are considered. The replacement of failed nodes is done in two phases: the first one is the search of redundant nodes using the clusterheads; the second phase is a restoration of connectivity. Performance evaluation of the proposed replacement approach shows that the results are globally satisfactory.     

Two Analytical Approaches for Solution of Population Balance Equations: Particle Breakage Process

Various particulate systems were modeled by the population balance equation (PBE). However, only few cases of analytical solutions for the breakage process do exist, with most solutions being valid for the batch stirred vessel. The analytical solutions of the PBE for particulate processes under the influence of particle breakage in batch and continuous processes were investigated. Such solutions are obtained from the integro‐differential PBE governing the particle size distribution density function by two analytical approaches: the Adomian decomposition method (ADM) and the homotopy perturbation method (HPM). ADM generates an infinite series which converges uniformly to the exact solution of the problem, while HPM transforms a difficult problem into a simple one which can be easily handled. The results indicate that the two methods can avoid numerical stability problems which often characterize general numerical techniques in this area.     

Effect of water salinity on the water retention curve of geosynthetic clay liners

The effect of water salinity on the water retention curve of geosynthetic clay liners (GCLs), under constant volume condition is examined. The results indicate that at a constant gravimetric moisture content the total suction increases as the salinity of the wetting liquid increases. Furthermore, the difference in total suction between the GCL hydrated by saline water and distilled water is greater than the difference in the osmotic potential of the wetting water. This behaviour is possibly caused by the matric suction being affected by the expected chemically induced pore size change of the bentonite component of the GCL.