.

This paper addresses a bi-criteria optimization problem to minimize total flow time and makespan simultaneously for a cellular flowshop with Sequence Dependent Setup Times (FMCSP with SDSTs); A multi-objective Particle Swarm Optimization (MPSO) and a Multi-objective Simulated Annealing (MOSA) Algorithm are proposed to solve the proposed problem. furthermore, an improved algorithm (named as IMPSO-TA), where MPSO is combined with Threshold Acceptance (TA) algorithm to improve the convergence of the obtained Pareto Fronts. The proposed algorithms are evaluated using several Quality Indicators (QI) measures for multi-objective optimization problems. Results showed that proposed algorithms can generate approximated Pareto Fronts in a reasonable CPU time. Furthermore, quality of Pareto fronts generated by IMPSO-TA is better than Pareto fronts found by MPSO and MOSA based on the test problems that are used in this research at the cost of CPU time. Further, the proposed IMPSO-TA performs as best available algorithms in the literature for small and medium test problems with a very minor deviation for best results for large test problems.

Engineering education has a crucial role in the economic and social development of society; this paper aims to investigate the most significant factors that contributing in improving the quality of the engineering education. Furthermore, identify the factors affecting the students’ academic performance. The study was conducted by using statistical Design of Experiments (DOE) approach to investigate the main effects of lecture delivery, assessment, engagement, communication, and interaction with instructors. Minitab software is implemented to perform statistical analysis to identify the significance of each factor, and degree by which each factor influences the students’ academic achievement. Results showed that the students’ academic performance is affected by the availability of course materials, and communications with instructors.

Oil spills are an unavoidable risk during exploration, production, and transportation. In the event of an accident, the environmental impact is often severe and may even harm the local environment for decades. Therefore, there is a need to find a method and device that minimizes damage to the environment. Oil spill cleanup and remedy are still a challenge and raise global concern because of the many environmental complications associated with it. This chapter reviews existing methods and devices for oil spill cleanup, particularly the wetting phenomenon for oil absorption and membrane filtration methods for oil spill cleanup, and focuses on the properties of nanofiber materials and their use for manufacturing oil absorbents and cross-flow filtration membranes. In particular, this chapter discusses the performance, effectiveness, and applications of nanofibrous materials fabricated by the solution and hot melt …

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.

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.