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.

The effect of Traverse speed on the microstructures of friction stir welded 6 mm thick austenitic stainless steel (304) plate has been investigated. Quantitative optical, high resolution scanning electron microscopy and Vickers hardness have been used to qualify and examine the microstructure through the plate cross section. The tool material was used is Tungsten Rhenium. For this work, friction stir welding was performed at rotation speed of 350 revolution per minutes (rpm) and traversing speed from 150 to 250 millimeter per minutes (mm/min) with an interval of 50 mm/min. Fine austenite has been observed in the stir zone, indicating that dynamic recrystallisation with no phase transformation occurred during FSW. The hardness profile is relatively homogeneous with slightly higher values in the stir zone than that of the base metal, suggesting that deformation and the cooling rate are dominant in the FSW process.

Traditional education depends on a set of basic elements, the most important of which are the educational curriculum, the lecturer, and the student, but these basic elements have been added to a new element in distance education, which is the electronic environment. During the COVID19 pandemic that began at the end of 2019 and the rapid transformation from traditional education to distance education and the involvement of distance education in implementing pre-prepared educational plans. This rapid transformation, in which the elements of education were not developed and not prepared in advance, led to the emergence of some problems in the educational outputs. Distance education, although its basic elements are the same as those of traditional education, the method of implementing it differed by introducing a new essential element, which is the electronic environment through which educational plans are implemented. In this research paper, the most important and influential actors in the educational process of distance learning and the problems resulting from this rapid transformation will be studied, then find appropriate solutions to keep pace with the development in the educational process, through an evaluation study of the experience of the Faculty of Science at Gharyan University. The results of this research will be useful to implement changes in the educational system and to meet the requirements of modern educational standards for higher education.

ABSTRACT In this paper, modeling, simulation and performance analysis of the three phase permanent magnet brushless direct current (PMBLDC) motor using Fuzzy Logic Controller (FLC), Genetic Algorithm controller (FGAC), hybrid Neuro-Genetic Algorithm Controller (NGAC), Hybrid -Fuzzy controller (NFC) and Hybrid Neuro-Fuzzy controller (NFC) based on Genetic Algorithm (GA) under the effect of external load for improving the transient and steady state response is presented. The applications of the three phase permanent magnet brushless direct current (PMBLDC) motor are increasing day by day. In order to have proper utilization of these motors and to control them effectively it is important to have proper mathematical modeling of these motors. Similarly effective control these motors are also essential to have successful application of the devices across multiple domains. This paper handles both these important aspects. A m been derived to represent a three phase permanent magnet brushless direct current (PMBLDC) motor model, its utility can be noted from the fact that different motors can be analyzed easily using the proposed model. The mathematical model was subjected to open loop and closed loop analysis to study the stability and performance. In this paper in order to validate the approach a MATLAB/SIMULINK model having intelligent controllers are constructed to control the modeled three phase permanent magnet brushless direct current (PMBLDC) motor under the effect of external disturbances for enhancement of static & dynamic response. 

Keywords Permanent Magnet Brushless Direct Current (PMBLDC) motor, Fuzzy Logic Controller (FLC), Genetic Algorithm (GA), Hybrid Neuro-Fuzzy controller (NFC) based on Genetic Algorithm GA, MATLAB/Simulink etc.

Due to an account of its excellent hardness and wear behavior, AISI D2 is used widely in producing of blanking and cold-forming dies, Punches, Shafts, Studs, and Bolts. Increasing toughness at a fixed high level of hardness is growing requirement for this kind of applications. Improving microstructure characteristics, especially carbides distribution by specific heat treatment, is an appropriate way to meet such requirement. The effect of quenching media on microstructure and hardness of pre-heated and austentized (at 980oC) AISI-D2 tool steel has been studied, and hardness and carbides morphology have been investigated. Three different medias, water, oil and water/oil (time quenching) have been used, then all samples were followed by the same tempering 350oC/1 hour. It has been found that the optimal carbides distribution and optimum hardness have been resulted from a time quenching method.