Groundwater is the main water source in Jifarah plain, northwestern Libya, which suffers from a continuous decrease in the piezometric head. This is due to the difference between aquifer recharge and amount of water drawn each year to meet the increasing needs of the population supply, agricultural and industry activities. These were study the design of the model is very close to the natural hydrological conditions in the reservoir.

Conceptual and numerical models were implemented in a regional scale to show change in the natural situation after the over-pumping, which occurred in the last decades. Results of the conceptual model indicated that the highest groundwater levels and the value of discharge per unit width of aquifers. 

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In this paper SiC particle reinforce aluminum metal matrix composite welded using high power continuous laser. Microstructure of laser beam welded SiC/Al MMC is characterized as functions of laser processing parameters. Results show that sound weld with little pores can be produced by laser beam welding, while aluminum carbide is formed in the weld. The size and the volume fraction of aluminum carbide are proportional to the laser power density. direction of shielding gas flow has significant effect on weld quality and weld microstructure.

Precoded spatial multiplexing multiple-input multiple-output (MIMO) systems using limited feedback have been extensively studied to reduce the feedback information based on the notion of delay-free feedback channel. In order to reduce performance degradation of precoded spatial multiplexing MIMO systems due to delay in the feedback channel, in this paper, we take into account the time varying nature of the channel, and consider the feedback delay problem. We propose the use of a linear predictor at the receiver to provide the precoder at the transmitter with predicted channel state information, and hence, mitigate the effect of feedback delay. The predictor is implemented using Kalman filter. The performance of this method is evaluated using computer simulation, and the achieved results demonstrate improved bit error rate performance in frequency selective Rayleigh fading channels.

Experimental and numerical investigations have been performed to study the natural convection heat transfer from a longitudinal fin arrays at different orientation angles. For such purpose, an experimental test rig was manufactured to be used for these investigations. It basically consists of base plate, an array of parallel longitudinal fins, heating unit and layers of thermal insulation. During the experiments, the fin spacing (S) was varied from 3.375 to 33 mm, while the fin height (H) from 15 to 60 mm. The orientation angle (Ф) was changed from 0° to 180°, and temperature difference between fin and surrounding (∆T) from 35 to 95 °C. To understand the general flow patterns dominating flows from the heat sink, the three-dimensionless elliptic governing equations were solved using finite volume computational fluid dynamics (CFD) code. A comparative study between the experimental and numerical results was performed to verify the numerical code. It was found for the configuration tested that the heat transfer rate per unit base area increases with the increase in the fin spacing and reaches a maximum value then decreases with farther increase in the fin spacing. The maximum heat dissipation occurs at optimal spacing 5. 6 S opt = mm. Moreover, the average heat transfer coefficient was found to have a maximum value at Ф = 0° and decreased with the increase of (Ф) to reach a minimum value at Ф = 90°. Empirical correlations between Nussult number, Rayleigh number, fin spacing, fin height, orientation angle, temperature difference between the fin and surroundings were derived.