Issue 1

Permanent URI for this collectionhttps://dspace.omu.edu.ly/handle/123456789/46

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CHARACTERIZATION AND OPTIMIZATION OF ERBIUM- DOPED FIBER AMPLIFIERS USED IN OPTICAL COMMUNICATION SYSTEMS
(Omar Al-Mukhtar University, 2017-09-01) Ali, Salema M; Mansour, Ibrahim
This paper deals with the properties of Erbium-doped fiber amplifiers (EDFAs). The EDFA is an optical amplifier that is used in the 1550 nm window of optical fibers. The objective of this work is to analyze and optimize the performance of EDFA systems with single wavelengths input sources. The Performance of optical communication systems is enhanced by the use of EDF. EDFA is an important element in Coarse Wavelength-Division Multiplexing (CWDM) and Dense Wavelength Division Multiplexing (DWDM) networks. The study can achieve gain spectrum by modeling the dynamic characteristics of an EDFA, and presents basic EDFA model operating on single (1550 nm) wavelength operation with their simulation results, then numerical simulations are used to evaluate the amplifier performance as function of manufacturing parameters and operating conditions, using this numerical model a computer program is developed to calculate the amplifiers gain and noise figure under certain conditions. The focus in this work is to study deeply EDFAs and then to improve the design for best performance (maximizing gain and reducing noise figure).
VARIATION OF BEARING CAPACITY OF SOIL WITH DIFFERENT PARAMETERS
(Omar Al-Mukhtar University, 2017-09-01) ABOOD, Tamadher T; Mohamed, MOHAMED A. S
Foundations of engineering structures are designed to transfer and distribute their loading to the underlying soil. This design is required to satisfy the main design criteria namely the bearing capacity of the foundation. Bearing capacity is affected by various factors like shape of footing, depth of footing ,change in level of water table, eccentricity of loading unit weight of soil ,etc. This research aims to investigate the effects of the shape of footing, its depth and location of water table on the bearing capacity of layered soil determined by Terzaghi, Hansen and Meyerhof methods .The main findings of this study are that the values of ultimate bearing capacity and safe bearing capacity determined for square and circular shaped footings are found to be higher than strip and rectangular footings. As depth of foundation increases ultimate and safe bearing capacity of soil increases. The bearing capacity of soil is reduced to about 50% when water table is near ground level.
Wind Characteristics & Wind Energy Potential in Libya : the case study in Derna
(Omar Al-Mukhtar University, 2017-09-01) Ahwide, Farag; Aldali, Yaser
In this paper the wind characteristics of seven sites in the windy regions in Libya have been analyzed, wind speed and wind direction were measured every 10 min at multiple levels for one year and half. The annual energy yield and wind direction were evaluated using the Weibull and Excel datasheet function, considering wind turbines ranging between 1500 W and 2000 W. Values of production of almost all turbines used are apparently good enough to think in three sites (Tarhuna, Derna and Al-Magrun) as a feasible site to develop a wind farm project in terms of economic parameters, in addition for approximately 2400 EqH as a reasonable value, Misalatha and Asaaba are suitable sites for a wind farm project in terms of economic parameters. On the other hand the values of EqH production is in general apparently not enough to think in Azizyah and Goterria towns, as a feasible value
ANTIBACTERIAL DRUG AS A GREEN CORROSION INHIBITOR FOR CARBON STEEL IN AQUEOUS SOLUTIONS
(Omar Al-Mukhtar University, 2017-09-01) IDRESS, A.A.; EMRAYED, Hanan F
Inhibitive and adsorption properties of ampicillin for the corrosion of carbon steel was investigated using chemical technique (weight loss method). ampicillin is found to inhibit the corrosion of carbon steel in 2M HNO3. Inhibition efficiencies of ampicillin increased as its concentration increases but decreased with increase in temperature. The adsorption of the inhibitor on the surface of carbon steel was found to be exothermic, spontaneous and followed the mechanism of physical adsorption. Also Langmuir adsorption isotherm was found to be the best isotherm that described the adsorption characteristics of the inhibitor.
The Effect of Ultrasonic Vibration on the Morphology of Intermetallic Compounds on the aluminum alloy A356
(Omar Al-Mukhtar University, 2017-09-01) KHALIL, A. A.; ABDULLA(, A. A
Refinement of intermetallic compound in Al-Si alloy is considered as an important task that results from solidification process. In general there are two different methods to the refinement of microstructure by solidification. The first one is chemically stimulated approach and the second one physically induced approach. The chemical method depends primarily on addition of grain refiner, where as the physical one relies mainly on the use of external field, such as ultrasonic vibration, which as the subject of this research work. In this research the effects of ultrasonic vibration on the morphology of iron-containing intermetallic compounds of A356 alloy have been studied. The mechanism of shapetransformation of Fe-containing phases such as β-Al5FeSi, δ –Al4FeSi2, α-Al15(Mn,Fe)3Si2 is also been investigated. The obtained samples were characterized by scanning electron microscopy (SEM), and EDS X-ray analysis( EDS). The results showed that the intermetallic compounds particles are in blocky form was significantly modified in shape and refined in size
STUDYING THE EFFECT OF THE ADDITIONS ON EXPANSIVE SOILS
(Omar Al-Mukhtar University, 2017-09-01) Mansour, Eman M
Expansive soils cause damages to civil engineering structures in various parts of the world, because they swell when absorb water and shrink when they dry out. Additional stresses applied to the structures due to the swell pressures are important in explaining some of the damages to the structures in expansive soils. Therefore the prediction of the swell pressures and taking them into consideration in the design of structures is needed. In this study, the relationship between the index properties and swelling characteristic of expansive soils is examined. The earlier studies showed that an increase in dry density and plasticity index of the soil cause an increase in swell pressure, while a decrease in natural moisture content cause an increase in swell pressure. In this paper, ALmarj soil will be used because of their properties to compare the swelling before and after adding the additions, that will be:- 1. Fine aggregate 2. Burned oil. These additions are choosing because they are cheap and recyclable available materials. The experimental study results show that, the soil properties after adding these additions have been changed with different ratio.
EFFECT OF ANCHOR DEPTH ON BEHAVIOR OF SHEET PILE WALLS USING PLAXIS 2D
(Omar Al-Mukhtar University, 2017-09-01) MUHAMMED, HUND S. ELNAJI
Sheet pile walls are structures used to retain soil, rock or other materials in a vertical condition. Hence they provide a lateral support to vertical slopes of soil that would otherwise collapse into a more natural shape. They have been used to support excavations for below grade parking structures, basements, pump houses, and foundations, construct cofferdams, and to construct seawalls and bulkheads. In order to have a more efficient usage of construction areas in congested urban areas a vertical development of buildings becomes necessary. Currently we more often face situations where urban buildings need as many parking spaces, so, due to lack of space, that requires the development of several underground floors. The design and execution of deep excavations in congested urban areas is quite a challenge especially in terms of geotechnical engineering and it requires a good knowledge of the soil mechanics and soil interaction with the retaining walls of the excavation. As such, the performance of support systems for deep excavation requires careful consideration of soil-structure interaction. This study involves 2D Finite element model is developed using PLAXIS to investigate the behavior of anchored sheet pile walls by varying different anchor location. The analysis is carried out considering non-linear behavior of soil using Mohr-coulomb failure criteria.

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