المستودع الرقمي لـكلية الهندسة

Abstract

This study is to develop the specifications of the present cement products so as to comply with the quality and quantities requirements of the local market. The subject of this thesis is to present the results of a series of laboratory trials on a number of raw material mixtures prepared to produce moderate and high sulfate resistance cement at EL- Mergheb cement factory which currently produces ordinary Portland cement. At first, six different raw material sample mixtures were prepared from marlstone,marl and iron ore. The clinker (cement ) produced from these samples was within the moderate sulfate resistance cement ( MSRC ) specifications which mainly requires the tri calcium aluminate (C3A) to be less than 8 % by weight. The trial runs on other three raw material samples made that from mixing marlstone , clay , and iron ore produced clinker specifications that were out of those for MSRC namely, C3A is greater than 8 % . This means that the addition of clay to the raw mix prevents the production of cement with MSRC specifications. This was due to the high percentage of Al2O3 in the clay . The specifications of the clinker products based on these results , MSRC was successfully produced at the factory from raw material mixtures ( marlstone, marl and iron ore ) without any clay addition . Finally three raw mix samples were prepared from marlstone, marl, iron ore, and sand and tested in the laboratory to explore the possibility of producing high sulfate resistance cement ( HSRC) which requires C3A to be less than 5 % . The results of these laboratory trials showed that when the sand in the raw mix is kept under 1.80 % , the produced clinker specifications are within those of HSRC. The permission to carry out these trials in the factory is underway. The expected economic benefits from producing both MSRC and HSRC is highly feasible. Both types will be sold in local market without any additional operating or capital costs .
صالح محمد صالح (2013)

Abstract

Today computers play an integral part in the analysis and design of civil engineering structures. Hand calculation is limited to simple structures, and initial member sizing (either during the preliminary design or prior to computer analysis). The matrix theory of structural analysis first began appearing in the early 1950s. Since that time, the engineers were not familiar with this new concept, hence a relationship between the matrix structural analysis, and the classical methods arise but the structural engineers as designers still follow the classical methods of solution such as, Hardy Cross moment distribution, Kani's method and deflection distribution ,method (D. D method) , etc. Structures that were too complicated to solve by classical calculations can now be handled with comparative ease when using computers. The analysis of complicated systems, such as highly indeterminate structures like space structures, grids-shells, etc. often could be handled by making many simplifying assumptions, to such extent, that in many cases the validity of the results had to be questioned. The use of computer techniques has broadened the scope of what the engineer can now handle in a reasonable time, and at a reasonable cost. Structures such as canopies, floor systems, and bridge deck systems. Are known as Grid structures. The members of a grid structure in general are subject to torsion as well as to shear and bending. Since the external loads are normal to the plane of the structure, the axial deformations are negligible. Consequently, a free joint in a grid is subject to a linear displacement perpendicular to the plane of the structure and to a rotation in the plane of the structure. It must be realized that the; use of so called matrix algebra methods and principles and methods of analysis, systematic matrix techniques have been now developed into recognized methods.
عمر على عودة (2009)

Abstract

Using the ground to produce condensate water for drinking and irrigation is A new application. This study simulates numerically the use of humid air flow in a buried pipe in the ground to obtain fresh water. The temperature difference between the humid air and the environment (ground) is exploited in this condensation process. The finite difference method is employed with pressure Correction method on staggered grid to simulate the flow of humid air through Buried pipes. The condensation occurs due to the decrease of the humid air Temperature below the dew point, as a result of the heat exchange between the humid air and the ground. The amount of condensation depends upon the flow Velocity, absolute humidity, Relative humidity and pipe geometry. For a selected pipe geometry of 22m long, and 0.2m diameter, the amount of condensation is about 26 kg/hr (0.006944kg/s). The results of the current study are in agreement to within ±10% of the results given by Jenney Lindblom.
مروان عبد السلام الهمشيري (2010)

Abstract

Water contamination is one of the major problems which the world is facing today. Water contamination not only effect environment and human health, but it has also impacts on economic and social costs. There are various ways used commercially and non- commercially to fight this problem which is advancing day by day due to technological progress There are many methods used for wastewater treatment, among these methods, the use of biological filters " trickling filter ", which depends on The basic idea is to get a larger surface area to get a better handle on the percentage. A composite media is used to replace the conventional stone in order to improve wastewater treatment in this thesis. The aim of this thesis to improve the performance of biological filters using nanotechnology, where to enhancing polymer media in biological and reinforced polypropylene by carbon fiber filters and talc by using electro spinning technology to produce the reinforced fiber that outlet from extruder. Design and simulate the extruder / die characteristics and studying The drag flow and pressure flow were then extracted from the screw parameters which lead into the calculation of the operation point and the operating pressure for the die. Also studying the effect of pressure and viscosity. Calculation of , and extruder characteristic is performed in order to allocate the operating point of the extruder.Two brand of carbon fiber are used in this thesis. The chapter type is at A tensile strength of 800 MN/m2. is selected. The operating pressure of the extruder is found to vary form 29.8 to 38.95 MN/m2 at an operating flow rate of 1.52*10-5 m3/sec. depending on the percentage of carbon fiber used in the blend.
محمود عيسى الفاما (2015)

Abstract

Wireless local area networks (WLANs) have been rapidly developed in recent years. It is used for various applications. VoWLAN, which transmits VoIP data over WLANs, shows its amazing attraction and constitutes one of the most flourishing applications nowadays in WLANs. One of Wireless Local Area Networks (WLAN) main drawbacks, when compared to wired networks, is that WLANs are less predictable and efficient. Wireless physical medium is harder to be controlled than physical wire. WLAN medium is also unlicensed, and thus susceptible to interferences produced by other devices. Therefore, great effort is being done in order to obtain Quality of Service (QoS) in real-time voice communications using WLANs. This topic has opened plenty of new research lines to upgrade current WLAN standards. In this thesis, a study is carried out for the behavior of new Medium Access Control (MAC) protocols defined in IEEE 802.11e draft standard Enhanced Distributed coordination function EDCF as well as for its subsequent modified versions. The Adaptive Enhanced Distributed coordination function AEDCF, designed to support QoS when providing voice communication services between stations in WLAN. Also presents experimental results obtained from simulations, and compare our results with simulations made using IEEE 802.11 standard MAC. The simulation work was done using NS-2 simulator, with the addition of specific modules for 802.11e. A performance comparison is carried out between the modified MAC scheme and IEEE standard MAC scheme, using Experimental simulation models. It is found that the adaptive technique method not only increases the medium utilization ratio and lowers the collision rate by more than 50%, but also enhances vii the overall throughput by around 20% compared with the basic IEEE 802.11DCF technique.
حسين ابراهيم ازويه (2010)

Abstract

: A 6MV and 15MV electron beams produced by the Elekta precise SL-25 linear accelerator at the Tripoli Medical Center (TMC) were modeled using the MCNP-4C code. Firstly the photon beam energies are tuned by comparison to experimental results previously performed at the TMC. Only the beam energy of the 6MV is modified to 6.2MV. Secondly the percent depth dose curves and beam profiles are calculated for the two energies in different field sizes in the water phantom. Matching with experiment is within an acceptable published allowance of 2%. The distances at which the maximum depth dose in the water phantom is reached are calculated as (1.5cm -1.7cm) for the 6.2MV setting and (2.7cm-3cm) for the 15MVsetting.
خديجة عمر بن ابراهيم (2011)

Abstract

: Modern PET/CT clinics consist of a scanner room housing PET/CT unit and a control area, two or more waiting rooms where patients rest prior to scanning, and a hot lab where doses are prepared. The 511 keV photons from the PET positron emitting isotopes are the source term for the waiting rooms and the hot lab, while both the 511 keV photons and the polyenergtic spectrum of x-rays from the CT unit must be considered in the scanning roomThis study is intended to estimate dose distribution resulting from using a FDG procedure (555 MBq). The dose distribution is evaluated in injection room, waiting room, and scanning room using two methods. The first method is the analytical method whids is based on AAPM report № 108, while in the second method the dose distribution was simulated using the Monte Carlo code EGSXYZnrc .In the Monte Carlo method some parameters such as the optimal number of histories and the cut off energy of the electron are found to have a significant effect on the results. These parameters are tested and those values with less statistical error are adapted for the calculations.A good agreement between the two methods has been achieved. The dose distribution in the uptake room , waitting room and the scanning room appears to be below the annually dose limit and does not exceed 1% at the adjacent areas.
مريومة البهلول القرقني (2009)

This research aims to build a model application of decision-making tools to solve problems associated with the contractor selection for Engineering, procurement and Construction (EPC) projects in the Oil and Gas sector. Taking into consideration the complexity of Oil & Gas projects in terms of technical, safety and environmental aspects, it is critical to choose a competent contractor to build quality plants as per scope specifications and within the specified time and budget. This study also covers problems associated with contractor short listing without proper contractors screening and pre qualifications activities, this might result in low cost bidding from non-competent bidders. Because current local tendering practices favors lowest price regardless of quality, this resulted in enormous problems when executing Oil & Gas projects such as projects failures and delays coupled with the absence of interest in our local market from reputed international EPC contractors. Because contractors screening and bid slate selection is a complex exercise that requires large amount of contractors data gathering and the associated analysis to achieve the required bidders short listing. Therefore, a model for contractors screening and selection was developed in this study where each contractor data base are gathered and analyzed. Such data includes discipline, previous activities, financial exposure, geographical locations, works backlogs and engineering capabilities. The Model called Analytical Hierarchy Process (AHP) was designed to improve contractor selection process based on established criteria. In this regard, 48 criteria and categories (mainly contractor capabilities financial, management, technical, resources etc.) were identified. They were mainly drawn from literature reviews, the author previous experience, lessons learned from past projects and NOC’s & IOC’s experience. The 48 categories, and based on subsequent meetings and discussions with several respected local Oil & Gas projects expertise, were divided based on relative importance to contractor selection process into two parts, Primary (7 categories) and Secondary (remaining categories). AHP is a compensatory decision methodology because alternatives that are deficient with respect to one or more objectives can compensate by their performance with respect to other objectives. AHP allows for the application of data, experience insight, and intuition in a logical and thorough way and enabling decision-makers to structure complexity and exercise judgment and allows them to incorporate both Goal Objectives (criteria), Sub-Objectives Alternatives objective and subjective considerations in the decision process. AHP enables decision-makers to derive ratio scale priorities or weights as opposed to arbitrarily assigning them. In so doing, in this research, (MS Excel) was used in addition to (Expert Choice), one of the prepackaged software that was utilized to study the sensitivity of the results and a case study of selecting a contractor. The AHP model is flexible and user friendly and can be applied at different stages of contractor selection process. In addition it can be utilized as a decision-making for a working group by analyzing the inputs of the working group members and highlighting deviations, biases, results and advising corrections. Utilizing AHP model encourages and promotes contracting good practice of national companies and institutions and enhances the decision-making capabilities and provides for a fair guidance while contracting for major Oil & Gas projects in Libya.
حسن محمد الشاوش (2009)