Data traffic load balancing and QoS in IEEE 802.11 network: Experimental study of the signal strength effect

The performances of multimedia applications built on wireless systems depend on bandwidth availability that might heavily affect the quality of service. The IEEE 802.11 standards do not provide performed mechanism for bandwidth management through data load distribution among different APs of the network. Then, an AP can be heavily overloaded causing throughput degradation.     

Renyi's divergence and entropy rates for finite alphabet Markovsources

In this work, we examine the existence and the computation of the Renyi divergence rate, lim_n→∞ 1/n D_α (p⁽ⁿ⁾∥q⁽ⁿ⁾), between two time-invariant finite-alphabet Markov sources of arbitrary order and arbitrary initial distributions described by the probability distributions p⁽ⁿ⁾ and q⁽ⁿ⁾, respectively. This yields a generalization of a result of Nemetz (1974) where he assumed that the initial probabilities under p⁽ⁿ⁾ and q⁽ⁿ⁾ are strictly positive. The main tools used to obtain the Renyi divergence rate are the theory of nonnegative matrices and Perron-Frobenius theory. We also provide numerical examples and investigate the limits of the Renyi divergence rate as α→1 and as α↓0. Similarly, we provide a formula for the Renyi entropy rate lim_n→∞ 1/n H _α(p⁽ⁿ⁾) of Markov sources and examine its limits as α→1 and as α↓0. Finally, we briefly provide an application to source coding     

Icosahedrons microstrip antenna network architecture proposal for new USS telecommunication subsystem

The paper presents a new antenna network subsystem architecture developed for application on board wireless communication subsystem. Founded research work results demonstrate the success of mathematical modeling and simulation of the proposed Icosahedrons Microstrip Antenna Network Architecture. Antenna elements are simulated, prototyped and tested. The Icosahedrons Microstrip Antenna Network is developed to meet the visibility requirements during inter small USS satellite radio communications.     

Modeling of Unsteady Turbulent Flow in a Buried Co-Axial Exchanger—The Use of Green's Functions Theory

This work presents an analytical and numerical investigation of the heat transfer problem of turbulent flow under forced convection in a buried co-axial exchanger. A hybrid model consisting of a finite element method at the boundary (BEM) for the heat transfer problem on the boundary, and a finite volume method (FVM) to solve the turbulent flow inside solves this complicated problem. The development of the BEM method is based on Green's functions theory. The mathematical model employed makes a scientific contribution to a similar practical situation. The results can be of great interest for industrial processes requiring the estimation of the heating time necessary to obtain steady states. Essentially, the axial evolution of the heat transfer coefficient versus Reynolds number and transfer duration is treated here. The temperature field and the heat flux density at the wall are also investigated.     

Emotion recognition in Arabic speech

Automatic emotion recognition from speech signals without linguistic cues has been an important emerging research area. Integrating emotions in human–computer interaction is of great importance to effectively simulate real life scenarios. Research has been focusing on recognizing emotions from acted speech while little work was done on natural real life utterances. English, French, German and Chinese corpora were used for that purpose while no natural Arabic corpus was found to date. In this paper, emotion recognition in Arabic spoken data is studied for the first time. A realistic speech corpus from Arabic TV shows is collected. The videos are labeled by their perceived emotions; namely happy, angry or surprised. Prosodic features are extracted and thirty-five classification methods are applied. Results are analyzed in this paper and conclusions and future recommendations are identified.     

Structural and Magnetocaloric Properties of ErFe 2 . 4 Al 0 . 6 Compound

The structural and magnetic properties of the single-phase pseudobinary ErFe _2.4Al _0.6 compound, obtained under arc-melting conditions, have been investigated. Single crystal X-ray diffraction analysis revealed that this compound is stabilized with a hexagonal CeNi ₃-type structure (space group P6 ₃ /mmc). The partial substitution of Fe by Al in this compound occurring at all the metallic sites is reflected in the decrease of the Curie temperature Tc. Magnetization curves (2–450 K; 0–5 T) indicate a ferrimagnetic ordering with four magnetic phases induced by competitional interactions between magnetic moments of both Er and Fe. The magnetocaloric effect has been estimated from the magnetic isotherms. The relative cooling power (RCP) value indicates relatively promising magnetic refrigerant material.     

A Methodology for a Semi-Automatic Evaluation of the Lexicons of Machine Translation Systems

The lexicon is a major part of any Machine Translation (MT) system. If the lexicon of an MT system is not adequate, this will affect the quality of the whole system. Building a comprehensive lexicon, i.e., one with a high lexical coverage, is a major activity in the process of developing a good MT system. As such, the evaluation of the lexicon of an MT system is clearly a pivotal issue for the process of evaluating MT systems. In this paper, we introduce a new methodology that was devised to enable developers and users of MT Systems to evaluate their lexicons semi-automatically. This new methodology is based on the idea of the importance of a specific word or, more precisely, word sense, to a given application domain. This importance, or weight, determines how the presence of such a word in, or its absence from, the lexicon affects the MT system's lexical quality, which in turn will naturally affect the overall output quality. The method, which adopts a black-box approach to evaluation, was implemented and applied to evaluating the lexicons of three commercialEnglish–Arabic MT systems. A specific domain was chosen in which the various word-sense weights were determined by feeding sample texts from the domain into a system developed specifically for that purpose. Once this database of word senses and weights was built, test suites were presented to each of the MT systems under evaluation and their output rated by a human operator as either correct or incorrect. Based on this rating, an overall automated evaluation of the lexicons of the systems was deduced.     

Cast Metal-Matrix Composites

The metal casting route offers considerable potential for the production of metal-matrix composites (MMC's) because of its near-net shaping capability which minimises machining requirements. The authors consider the metal-casting route in context with other shaping methods for MMC manufacture. Factors of importance, such as melt preparation and solidification processing, are reviewed before experimental details are described. The properties of MMC's based on the Al-Cu, Al-Mg and ZA alloy systems, and produced by squeeze casting, are discussed.     

Texturing and Instant Cooling of Rapeseed as Pretreatment Prior to Pressing and Solvent Extraction of Oil

Instant controlled pressure drop process (DIC) was used to texture rapeseeds in order to intensify oil extraction performances of both pressing and solvent extraction processes. Solvent extraction from both DIC-textured and non-treated raw material RM seeds was achieved with n-hexane using separately accelerated solvent extraction (ASE) and dynamic maceration (DM). ASE allowed quantifying the extraction yields while the extraction kinetics issued from DM experimental data was studied through coupled washing/diffusion CWD phenomenological model. ASE oil contents were 622.5?±?0.5 and 664.4?±?0.5 g oil/kg dry dry basis ddb for untreated and DIC-textured seeds, respectively. In terms of kinetics, 45-min DM of DIC-treated seeds implied higher yields than 8-h DM of RM (467.8?±?0.5 against 435.6?±?0.5 g oil/kg ddb). Moreover, pressing oil yields reached 553.5?±?0.5 against 490?±?0.5 g oil/kg ddb for DIC and RM seeds, respectively. Besides, optimized DIC treatment allowed obtaining preservation of lipid fatty acid profiles.