MPC: A RSUs deployment strategy for VANET

A Vehicle AdHoc Network is mainly composed of mobile vehicles and fixed Road Site Units (RSUs). The latter is usually very expensive to deploy and has a crucial role in maintaining the network connectivity. Therefore, the design of an efficient RSU deployment strategy that enables a high coverage ratio and a lower deployment cost has been of paramount importance. In this respect, we introduce in this paper a new spatiotemporal coverage strategy for nonsafety Vehicle AdHoc Network applications like driving assistance and business promotion, called Minimal Mobility Patterns Coverage (MPC). The main thrust of MPC is to (1) depict the mobility patterns of moving vehicles from their trace files and then (2) compute the adequate RSU locations in order to cover the extracted mobility patterns by the minimal possible number of RSUs. To this end, we firstly provide a new method to depict the mobility patterns of vehicles by mining the correlations between the kept track connections of vehicle trajectories versus crossed junctions. Secondly, we introduce a new way to compute the adequate RSU locations through the instantiation of the well‐known problem of extracting minimal transversals of a hypergraph. Experimental results show that our RSUs deployment strategy performs better than baseline strategies.     

Résistance à la traction et module d’élasticité des bétons calcaires: application à des mélanges tunisiens

This article presents the results of the tensile strength and the elastic modulus obtained between one day and a year on a vast set of mortars, micro-concretes and concretes carried out with limestone aggregates out coming from five Tunisian careers. For the tensile strength, the results were compared with the compression strength measured on the same mixtures. The obtained evolutions do not coincide with the power-laws generally adopted for the predicted tensile strength. An approach, where the law parameters (coefficient, exponent) can be adjusted, gives better results. The resort to another more precise model, described by a hyperbolic law, makes it possible to provide a physical interpretation to the tensile strength behavior of the hydraulic mixtures. Its parameters are linked to the aggregate strength and cohesion in the paste-aggregate transition zone. For the elastic modulus, the use of a model taking into account the properties of the granular phase and the binding phase made it possible to reach the elastic modulus of the aggregates.

Insight of DFT and atomistic thermodynamics on the adsorption and insertion of halides onto the hydroxylated NiO(1 1 1) surface

Spin polarized, DFT + U periodic calculations have been used to study the interaction of halides (X) with a (1 × 1)-hydroxylated NiO(1 1 1) surface, a model of passivated nickel. The exchange of surface OH groups by the X ions and the insertion of the halides in the anionic sub-surface layer have been investigated. The substitution of OH by halides is favored by a smaller size of the halide ions and by a lower substitution proportion. An atomistic thermodynamic approach including solvent effects allows us to construct phase diagrams of the surface terminations as a function of the Cl and F concentrations in the aqueous solution. The higher proportion of OH substitution by F, and the lower insertion energy, as compared to Cl, may be related to stronger corrosion caused by F as compared to Cl.     

Traveling-wave dual-gate MESFET: A multimode S-matrix derivation based on the quasistatic approach

A theoretical model of the dual-gate MESFET including electromagnetic propagation effects is presented. The quasistatic approach is induced by the presence of a constant volumic charge density in the depletion layer when the device operates under the slow-wave Schottky mode. Device features are analyzed, through its S-parameter variation vs. electrode length, frequency, loading impedances, and bias voltages. We found that the different propagating mode attenuation factors are determined principally by the conductor losses. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 11–19, 1998.     

Adaptive vectorial lifting concept for convolutive blind source separation

This paper describes a new multi-resolution approach for the blind separation of convolutive image mixtures in transform domain. The proposed method uses an Adaptive Vectorial case of Quincunx Lifting Scheme (AVQLS), based on wavelet decomposition, and a geometric unmixing algorithm. It proceeds in three steps: first, the mixed images are decomposed by AVQLS. Then, the unmixing algorithm is applied to the more relevant component to get a transformed estimate of the original images. An inverse transform is, thereafter, applied to obtain an estimate of the original images. Experiments carried out on medical images showed that the proposed method yields better separation results than many widely used blind source separation algorithms.     

Modeling of surface plasmon resonance nanobiosensor with the transverse resonance method

This article describes a new approach for the detection and identification of a molecular interaction in real‐time and non‐label with surface plasmon resonance (SPR). This approach is based on the transverse resonance method, modeling the nanobiosensor by an equivalent circuit that allows studying the dispersion characteristics of surface plasmon and the reflectivity. The results obtained from these two studies show that the dispersive study is very precise than the reflectivity one to determine the presence and nature of molecular interactions.     

A new multi-scale framework for convolutive blind source separation

This paper presents a new multi-scale decomposition algorithm which enables the blind separation of convolutely mixed images. The proposed algorithm uses a wavelet-based transform, called Adaptive Quincunx Lifting Scheme (AQLS), coupled with a geometric demixing algorithm called Deds. The resulting deconvolution process is made up of three steps. In the first step, the convolutely mixed images are decomposed by AQLS. Then, Deds is applied to the more relevant component to unmix the transformed images. The unmixed images are, thereafter, reconstructed using the inverse of the AQLS transform. Experiments carried out on images from various origins show the superiority of the proposed method over many widely used blind deconvolution algorithms.     

The Characters of a Sylow p-Subgroup of the Group G2(pn), p≠2, 3

 We compute the irreducible complex characters of a Sylow p-subgroup of the Chevalley group G ₂(q), q=p ⁿ , p≠2, 3 and show that the non linear irreducible characters are induced from linear characters of subgroups of order q ⁵ and q ⁴. Received April 6, 1995