This paper introduces a new call admission control (CAC) mechanism for Long Term Evolution (LTE) networks supporting multimedia services with different classes of traffic. Our CAC mechanism classifies calls into real time and non-real time users, then estimates the channel quality based upon the received signal strength (RSS) value, and finally identifies the call as either new call (NC) or handoff call (HC) request before performing admission control decision. We also use a simple preemption technique in order to allocate the resources to high priority bearer requests. We show through extensive simulation analysis that our CAC mechanism provides high number of accepted users with higher priorities while providing high system throughput.

This study detailed the effect of simultaneous multiple intrinsic and extrinsic factors on the characteristics of Sfax activated sludge wastewater treatment plant (WWTP), located in Southern East Tunisia. The plant performance was evaluated through descriptive and statistical analysis of quantity and quality data of both raw wastewaters and treated effluent over a period of three years (2008-2010). Despite the rehabilitation, poor performance was shown to be attributed to raw wastewaters quality, civilization populations, bad functioning of the aerators and the industrial fallouts and deposits. Therefore, the downstream values of BOD 5 , COD, SS, FC, FS, TKN and TP are enough to achieve a final effluent that would meet the Tunisian standards limit. Multiple regression analysis showed that removal efficiencies of BOD 5 , COD and SS can be predicted to reasonable accuracy (R 2 = 0.973, 0.946 and 0.925, respectively). Goodness of the model fit to the data was also evaluated through the relationship between the residuals and the model predicted values of BOD 5 r, CODr and SSr. The advantage of this model is that it would allow a better process control.

The objective of this study was to identify the organic compounds removed from the leachates when treated with coagulation-flocculation and Fenton-Adsorption by gas chromatography coupled to mass spectrometry (GC-MS) in order to identify toxic compounds that could be harmful for the environment or human health. Physico-chemical characterization of the raw leachates (RL) was carried out before and after the aforementioned combined treatment process. The effluent from each stage of this process was characterized: pH, Biological Oxygen Demand (BOD 5), Chemical Oxygen Demand (COD), turbidity and Total Suspended Solids (TSS). The organic compounds were determined by GC-MS. The removal of COD and BOD 5 reached over 91% in compliance with the Tunisian Standards (NT 106.002-1989), which establishes the maximum permissible limits for contaminants present in wastewater discharges to urbanized streams. The chromatographic analysis from the Adsorption effluent proved that this treatment removed more than 99% of the organic compounds present in the initial sample. The phytotoxicity test showed that combined treatment process allowed a significant toxicity removed (92.2%). The mono (2ethylhexyl) ester 1,2-benzenedicarboxylic acid persisted, although it is not considered as toxic compound by the NT 106.002-1989) Therefore, the treated effluent can be safely disposed of into the urbanized streams.

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