Enhancement of voip and video streaming performance over IEEE802.11e WLAN

There are various versions of IEEE802.11 WLAN in the market, and each applies different modulation technique and operates in different frequency bands. For example, the IEEE 802.11 b version provides data rates up to 11 Mb/s on the wireless medium, applying complementary code keying (CCK) and direct sequence spread spectrum (DSSS) as modulation technique. It operates in the industrial, scientific, and medical (ISM) band at 2.4 GHz. On the other hand, the IEEE 802.11 a version operates in the unlicensed 5 GHz band, and provides data rates up to 54 Mb/s on the wireless medium, applying the multicarrier technique orthogonal frequency-divi sion multiplexing (OFDM) as the modulation technique [1]. The 802.11 g version applies the same multicarrier modulation technique as 802.11 a, but operates in the 2.4 GHz ISM band like 802.11 b. However, due to channel conditions and protocol overhead, the maximum achievable throughput on the MAC layer is less than the data rate available on the wireless medium for the mentioned IEEE 802.11 version

CONTRIBUTION TO THE RECOGNITION OF THE STRUCTURE OF TASSAOUT DOWNSTREAM OF TADLA BASIN THROUGH THE APPLICATION OF GEOELECTRIC METHODS

Geoelectric study is used in determining the image of the structure of the aquiferous system of the Tadla plain (Tessaout aval) through the measure of electric soundings. The treatment processing of these measures, their correlation with the data of certain drilling, the well existing in the canvassed area, and the analysis of all the results, shows that the study area of the profiles and the maps of the established electrics resistivities and clear geoelectric cups gives a general looks. This put the superimposing of several variables as evidence. Roughly speaking, grounds draws a structure of monoclonal wrinkle sometimes tectonised, which dives the Northwest towards the Southeast. This structure is affected by a series of flaws which are causing the collapse of compartments which are located in the South

Simulation of Transonic Compressor Performance Deterioration Due to Sand Erosion

Air sand erosion is a widely effecting phenomenon in GCC region, where a solid particle impacting on a wall surface causing catastrophic mechanical damage, the engine compressor operating in a particulate environment are subjected to deterioration of performance and life due to sand ingestion. In current paper we simulate and studied the sand erosion in such transonic compressors were flow rate, particle size and concentration were investigated to study particles distribution and erosion rate along the compressor blade. Result shows that particles concentration has the most significant effect on blade erosion rate where particles size has less effect among all other measured parameters. Surface deformation and roughness is in scope for further investigation

In vitro antifungal activity of the soap formulation of the hexane leaf extract of morinda morindoides (morinda; rubiaceae)

Purpose: The aim of this study was to formulate the hexane extract of the leaves of Morinda morindoides (Baker) Milne-Redh (Rubiaceae) as soap and evaluate its antifungal activity against fungal isolates of human origin. Method: The hexane extract of Morinda morindoides was incorporated as an antifungal agent in soap (SMM) and tested against 4 strains of dermatophytes (Candida albicans, Trichophyton rubrum, Trichophyton mentagrophytes and Aspergillus fumigatus) using basic soap (BS) as control. Agar dilution method at serial concentrations ranging from 125 mg/ml to 3.9 mg/ml was used for the determination of the antimicrobial parameters - MIC (minimum inhibitory concentration) and IC50 (concentration producing 50 % inhibition) for these strains.Result: The growth of all fungal strains tested was inhibited by the Morinda morindoides extract soap (SMM) at MIC of 31.25 mg/ml. On the other hand, basic soap (control) inhibited Candida albicans at MIC of 125 mg/ml and at MIC of 62.50 mg/ml for the other 3 strains tested. Thus, SMM showed stronger antifungal activity against the strains tested than the control (basic soap). Conclusion: The hexane extract of Morinda morindoides leaves incorporated in soap exerted antifungal activity against the fungal strains tested. Thus, this soap formulation may find use in the treatment of dermatomycoses.Keywords: Morinda morindoides; Antifungal activity; Hexane extract; Soap; Dermatophyte

ANN-Based Failure Modeling of T-56 Engine Turbines

The T-56 turboprop engine is one of the most widely used in military transportation aircraft. It operates virtually everywhere, from the arctic circle to the Sahara. Operation in desert conditions, however, presents a challenge for maintenance engineers regarding preventive maintenance scheduling. Erosion caused by sand particles drastically decreases turbine blades life. Recent studies showed that Artificial Neural Network ANN algorithms have much better capability at modeling reliability and predicting failure than conventional algorithms. In this study, more than thirty years of local operational field data were used for failure rate prediction and validation using several algorithms. These include Weibull regression modeling to establish a reference, feed-forward back-propagation ANN, and radial basis neural network algorithm. Comparison between the three methods is carried out. Results show that the failure rate predicted by both the feed-forward back-propagation artificial neural network model and radial basis neural network model are closer to actual failure data than the failure rate predicted by the Weibull model. The results also give an insight into the reliability of the engine turbine under actual operating conditions, which can be used by aircraft operators for assessing system and component failures and customizing the maintenance programs recommended by the manufacturer

On the Link Between Strongly Connected Iteration Graphs and Chaotic Boolean Discrete-Time Dynamical Systems

Chaotic functions are characterized by sensitivity to initial conditions, transitivity, and regularity. Providing new functions with such properties is a real challenge. This work shows that one can associate with any Boolean network a continuous function, whose discrete-time iterations are chaotic if and only if the iteration graph of the Boolean network is strongly connected. Then, sufficient conditions for this strong connectivity are expressed on the interaction graph of this network, leading to a constructive method of chaotic function computation. The whole approach is evaluated in the chaos-based pseudo-random number generation context

Failure analysis of a steel motorcycle kickstand

Copyright @ 2009 Springer US.A fractured steel motorcycle kickstand was metallurgically investigated using a range of failure analysis tools [visual examination, energy dispersive X-ray (EDX) analysis, electron microprobe analysis (EPMA), scanning electron microscopy (SEM), fractography, optical microscopy, hardness testing and non-destructive testing (NDT)]. The steel kickstand’s composition, its microstructure, electron fractographs, and mechanical test results have been critically interpreted. Some evidence of wear damage, in the failed kickstand, was observed. The microstructural and fractographic analyses showed pre-existing micro-cracks which were believed to have grown to result in ductile failure followed by acceleration of corrosion. Recommendations have been made to avoid the failure of the motorcycle kickstand

Analisis Pegaruh Persepsi Harga dan Iklan TV terhadap Keputusan Pembelian Kembali Produk Sunlight

Studi ilmiah ini bertujuan untuk menganalisis hubungan antara faktor persepsi harga (perceived price) dan iklan tv (tv commercial) dengan keputusan pembelian kembali oleh konsumen pada produk sabun cuci piring cair merek Sunlight, di Provinsi DKI Jakarta. Penelitian dilakukan menggunakan data primer yang berasal dari 200 responden yang merupakan ibu rumah tangga yang pernah membeli Sunlight dengan rentang usia antara 25-50 tahun. Penelitian dilakukan dari bulan Agustus hingga September 2013. Metode yang digunakan dalam penelitian ini adalah metode penelitian kuantitatif, dengan analisis regresi linear sederhana dan berganda. Adapun hasil penelitian menunjukan bahwa faktor harga dan juga iklan tv memiliki pengaruh yang signifikan terhadap keputusan pembelian kembali oleh konsumen pada produk sabun cuci piring cair Sunlight. Melalui uji keragaman diketahui bahwa kelompok usia memiliki keragaman dengan tingkat signifikansi 0,005 atau sebesar 5%

Perceived health and quality of life: the effect of exposure to atmospheric pollution

International audienc