This paper describes three schemes to implement Direction of Arrival Estimation (DOA) that is used and implemented in real Antenna system. The variation between those algorithms is important in means of accuracy and complexity of implementation such mathematical models in actual system of Antenna. The use of mathematical analysis is very helpful to understand the process of DOA estimation and each part of the algorithms in the study, so that can be used further to implement algorithms and work on MATLAB to investigate and evaluate the performance of each one in relative with the others and how they act when they put in same conditions with different number of samples and using different factors. The used algorithms for the study are the conventional algorithms Bartlett & Capon, in contrast with more advanced algorithm MUSIC Multiple-Signal-Classifications, which is introduced as the main focus in the study. Simulation of DOA is made using MATLAB and the mathematical implementation of the three algorithms. The results of comparing thealgorithms shows that varying number of samples taken has a crucial role on determining Direction of Arrival or the incident angle of the input stray-signal at the arrays of the smart antenna which senses the direction based on the algorithm operated in the smart antenna system, the use of the three algorithms in different number of samples had shown a performance change of accuracy of estimation in different way for an algorithm in comparison to another algorithm in many circumstances, the more prevailing fact is that the more number of samples the more accuracy of estimation, but in case of less samples the Bartlett algorithm showed better performance in compare to other algorithms, as for Capon algorithm it suffers accuracy at low number of samples and need high number of samples to act more accurately, as for MUSIC algorithm it shows the best overall performance as adapting fast to the angle of estimation with high accuracy in response to an efficient number of samples.

ABSTRACT

Libya is one of the largest countries in the olive oil production leading to

generate massive amounts of olive-waste cakes during the manufacture process

every year. Therefore, this experimental study aims to investigate the potential of

olive-waste cake as a low-cost natural source for preparation activated carbon

(AC). The solid olive oil mill residue was carbonized at 200 0C and chemically

activated using two methods including Model I (25% Zncl2) and Model II (25%

Zncl2 + 25% H2SO2) . To investigate the efficiency of prepared AC,decolourization of methylene blue founded in an aqueous solution was conducted. The effectiveness of this process was studied via key parameters

effects such as contact time, pH, and AC dose. The achieved results showed that

the decolourization using Model II was more than of Model I. The optimum

values of pH, contact time, and AC dose were 5, 120 min, and 2.5 g/L

respectively. At these conditions the maximum methylene blue removal was

75%. The results indicate that olive-waste cake has a potential in future water

treatment applications due to its high adsorption capacity.

The proposed method provides a good tracking performance through detecting the variation in the wind speed rapidly. In addition, the implementation does not require prior information on the wind turbine parameters, air density, or wind speed. By investigating the change directions of the mechanical output power of the wind turbine and the rotor speed of the generator, the proposed MPPT algorithm can determine an optimal speed to achieve the maximum power point (MPP).

Then, this optimal speed is set to the reference in the speed control loop to force the system to operate at the MPP. The DC-DC boost converter has been used to boost up the low AC voltage generated by the PMSG directly driven by the wind turbine. The mechanical output power of the wind turbine is calculated from the mechanical torque which is measured directly by sensor.

The proposed scheme is modeled and simulated under SIMULINK/MATLAB. The simulation results are accurate and validate the wind energy conversion system.

Keywords: Wind Turbine, maximum power point tracking (MPPT), permanent magnet synchronous generator (PMSG), wind energy conversion system (WECS).

An attempt has been made to evaluate the effect of welding parameters on the weld penetration, weld bead width and heat effective zone of Tungsten Inert Gas (TIG) welded 2 mm 304L stainless steel joints. The welding parameters including arc current, welding travel speed and gas flow rate were used to achieve the optimum joint. Taguchi technique has been implemented to optimize the welding parameters. Orthogonal array L9 (Three factors with three levels 3x3) was used to study the effect of arc current, welding travel speed and gas flow rate on the quality of 304 stainless steel welds. Signal to a noise ratio (SNR) and the analysis of variance (ANOVA) are also used to determine the main effects of different welding parameters on the weld bead width (WB), weld penetration (WP) and heat affected zone (HAZ). Results showed that welding current has significant effect, whereas gas flow rate showed no effect on the quality of 304Lwelded joints. Welding current of 185A, welding speed of 135mm/min and gas flow rate of 15lit/min have been selected as the best process parameter of weld bead width and weld penetration at level three of experiment seven. However, the optimum process parameter for heat affected zone are level one experimental three at165 A, 235 mm/min, 15 lit/min of welding arc current ,travel speed and gas feeding rate, respectively.

ABSTRACT

Water sources in Al-Jabal Al-Gharbi area are very limited and need to be studied for use either as drinking water or human activities. Therefore, several physical and chemical parameters of water sources in Al-Jabal Al-Gharbi region located in Northwest of Libya were investigated. For untreated water three sources were studied including groundwater wells, rain water, and Man-Made River (MMR). However, for drinking water packed and unpacked treated commercial water were investigated. The examined properties were pH, conductivity, salinity, turbidity, total dissolved solids (TDS), chlorine, nitrates (NO- ), nitrites, sulfate, phosphate, iron, and cupper. The results showed that the groundwater and MMR water had high TDS concentrations between 1115 and 4090 mg/L leading to increase the total hardness in these samples. Most of the treated waters had very low of TDS concentrations causing loss the useful salts for consumers . However, the rain water samples had optimum values of TDS and other parameters. Regarding NO- all samples were within the limitation and in the range of 0.02 to 15 mg/L. Furthermore, all metal ions examined in this work such as iron and Cupper were within the WHO guidelines.

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Abstract

The present work was carried out in order to investigate the physical and chemical quality of the Libyan Asbi'ah groundwater and the degree of its contamination. The achieved results were compared with international quality standards for drinking water. The sampleswere collected from five water wells of the Asbi'ah region. Several parameters were examined including Colour, Taste, smell, pH, total dissolved solids (TDS), Calcium and Magnesium Hardness, Total Hardness, Iron, Fluoride, Ammonia, Phosphate and Chloride. The results showed that the groundwater of Asbi'ah area were within the limitations of WHO Standards. For instance, the maximum values of Fe, PO4, F, NH3 and Cl were (0.92, 0.16, 1.2, 0.05)mg/L respectively. However, some samples had a bit high of concentrations for TDS (590mg/L) and Total Hardness (702mg/L). The most of the water wells shared the high concentration of Total Hardness which might be due to the earth geology of the studied area. This makes the water taste unacceptable and therefore, the water might not be used as drinking water.

Keywords: Natural Groundwater, Chemical & Physical Properties, Contamination, Asbi'ah -Libya.