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.

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.

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.

the purpose of this paper is to use discrete event simulation to model breakdowns of filling machines for food manufacturing line. It presents an approach to model breakdowns based on purely historical data where MTBF and MTTR have been extracted in order to replicate the existing machine and the breakdown occurrences. The historical data gathered from the operations department were first analysis over a period of 28 months in order to extract the Failure and repair distributions of machines; these statistical distributions were applied in the first model.

The data were also used to calculate the components of the OEE of the filling line to identify potential areas of improvement.

The models were built using Arena Simulation Package; the simulation used to represent the filling line machines with a series of elements and built in templates in addition to animation tools to improve the display at the human interface. Simulation enables the replicating of the business model in a computer system totally risk free, as you can apply and make changes to the model, create “what if” scenarios to test strategic changes, and extract results.