المستودع الرقمي لـكلية الهندسة

Abstract

In wireless communication systems the data rate, capacity, coverage, and spectral efficiency; can be enhanced with multi-carrier transmission and multi-antenna, then the overall wireless communication system performance is greatly enhanced by combining OFDM and MIMO schemes, MIMO helps in increasing the throughput where as OFDM spreading out the frequency selective fading channel over many symbols. In this thesis evaluating performance of the system depends on both link and system levels, where the measure of performance is represented in the throughput, cell radius and the effective signal to interference plus noise ratio (SINR). It also depends on the employed capacity criterion and it takes into account the impact of adaptive modulation and coding. the worked scenarios start from a link level extending to a system level in 3GPP LTE. To achieve the above a number of tasks followed by observations are carried out. They start by analysis of the equations and a Matlab program is written to calculate the cell edge throughput, cell coverage and DL capacity. After the programs implementation, the multi antenna transmission effect is noted on the arrival throughput when taking into account the modulation technique. When increasing the order of the antenna and the throughput is also increased, but it must be traded off with the probability of error; Coverage has also improved by decreasing the order of the modulation technique. For the system level with different traffic, the overall throughput of the system and the capacity of the network are determined by the number of resource blocks (RBs). These RBs depend on the bit rate of the service and bit rate for each RB. The adopted scenarios in this thesis start from link to system, where the features are represented in a flexible base station and user configurations, channel modeling with path loss, user mobility, also at different transmitter and receiver (MIMO). The approaches are useful in single user and multi-user MIMO, then all of the above can be standardized by metrics: capacity, throughput, spectral efficiency, user QoS etc. Finally thesis conclusion and some future work as an extension of this work are presented.
احمد محمد التانزفتى (2013)

Abstract

Many of the concentrating solar power (CSP) systems are expected be installed in desert locations where lack of water and sand storms might be an issue. The solar reflectors are considered to be among the main effective components. The negative effects of the harsh weather conditions, including sand storms of the desert might have strong influence on the reflector properties, leading to a decrease in the thermal performance of such solar system. This thesis studies the sand storm influence on solar reflector surfaces, where two different types of Libyan sands were considered and taken from sites suitable for the installation of CSP. These sands have different shapes, sizes and chemical compositions. Sand "A" has particle sizes that vary from 0.025 to 0.355mm, while Sand "B" has particle sizes in the range of 0.124-0.479 mm. An erosion rig was designed and built at Cranfield University, UK. the tests were conducted under different simulated sand storm conditions for both sand samples. The results have shown that Sand "A" has more severe influence than Sand "B" because the smaller particles of Sand "A" help the spread out over a larger surface area of the reflector. The higher sand storm speed has more strong impact influence, while increasing the mass quantity results in less consequences. The reflectivity of the un-cleaned surface drops by 5% in case of using Sand "A" and by 7% in case of Sand "B", both at storm speed of 21m/s with specific sand mass of 18g/m3.Sand storms with the speed exceeding 6 m/s, generate sand impact on the reflector surface causing degradation to the surface, while storms with speeds less than 6 m/s, result in wakes of suspended small particles as a consequence of the transport mechanism in the atmosphere. Sealing simulation and cleaning process, using Ultrasonic Cleaner Model, show that sand "B" makes a loss of about 3% of the surface reflectivity, due to the salt-chemical composition leading to create spots and marks on the reflector surface. However, Sand "A" has recorded no chemical reaction. Sand storm history should be taken seriously, reflector surface materials should be suitable for the sites, and cleaning operations should be considered.
عصام ميلاد اندايا (2015)

Abstract

Matrix acidizing is a stimulation method commonly used to remove near wellbore damage and restore original formation permeability. It involves the injection of acid into formations at pressures below the fracture pressure. Acid flows down the well into the reservoir, and then reacts with the rock such that any near wellbore permeability damage created by meling or completion fluids can be removed and apparent permeability increased. A matrix acidizing treatment can be' applied to either a sandstone or a carbonate reservoir. Different acids are used because different minerals are involved in these treatments. Hydrochloric acid (HCI) is usually used in carbonate reservoirs to react with carbonates. Hydrofluoric acid (HF) or mixture of Hydrofluoric acid (HF) with Hydrochloric acid (HCI) is commonly used in sandstone porous media to react with silicates and feldspars in the rock. Since the mechanisms of acid reactions with these two types of rock are different, results of the treatments are different as well. In sandstone matrix acidizing, permeability increase behind the acid front is relatively homogeneous. The flow and reaction of acid in carbonate porous media results in the formation of highly conductive flow channels, commonly referred to as wormholes. In the present work we have studies the first study to test the optimal acid flux theory presented by Wang (1) with several independent sets of experimental data. The model was comparing with field data. The second study we use model presented by McCune and Fogler.(2) This previous studies on mathematical modeling of the chemical reactions between sandstone and mud acid. This model is lumped-parameter model. The lumped-parameter model simplifies the chemistry of the dissolution of sandstone minerals with mud acid. The models are compared with the experimental data at different flow rates.
عبد ربه ادريس بوسدرة (2010)

Abstract

Measurements of in-situ data for geomechanical parameters are very essential part of geotechnical engineering design, but the time and the budgets are major issues, The design engineer must make critical decisions at several steps throughout the design stages to obtain the most reliable and realistic soil and rock property information. Because of that, the empirical equations are increased in use during the early stages of engineering design work. In any geotechnical investigations, most probably, will be involved in using Standard Penetration Test (SPT). It is a very popular test among geotechnical engineers. Therefore, it will be economically very useful if the results of SPT as N-values could be used to calculate the other geomechanical parameters. The sites of investigation are the Zawia Combined Cycle Power Plant, West Mountain Power Plant at Rowies, Tripoli and Tunisa. The data were collected from 13 boreholes, and more than 160 points. Which gave wide reliable results. Field investigations include Cross-Hole, Down-Hole seismic techniques, Standard Penetration Test SPT, Cone Penetration Test CPT and pressuremeter test PMT. The variation of seismic waves velocity (Vs & Vp) and dynamic modulus (shear modulus, young modulus, and bulk modulus) of sand and weak rock were studied and some correlations were developed. Also the effects of depth on the correlations were investigated. The correlations compared with previous relationships. The results showed that the power function provides the best fit for correlation between seismic wave’s velocity and dynamic modulus data with SPT N-value. The correlation coefficient (r) range 0.77-0.54 for sand and for weak rock. Range is 0.82-0.58. The multiple power regression analysis enhanced the correlation coefficient of sand and weak rock to ranges 0.82-0.58 and 0.97-0.92 respectively. These results are higher than the previous results. A single value of geotechnical parameters is very difficult to determine because the properties of material vary from point to point in the way that, it depends on a set of conditions so geotechnical parameters (seismic waves velocity and dynamic modulus) were determined between an upper and lower limits. The results of statistical analysis of relationship between SPT N-value and Cone Penetration Test (tip resistance qc) for all available data show that a linear regression with zero intercept as best fit correlation. of r=0.77. This result is equivalent to previous work. The logarithmic regression gave the best fit for the correlation analysis between the pressuremeter modulus EPMT and N value by r=0.81. The relationship between the limit pressure PL and N value was shown that, the linear regression was the best fit. The best-fit regression indicated a logarithmic relationship between the pressuremeter modulus (EPMT) and limit pressure (PL), with r=0.81 and 0.66 respectively.
ملاك عبد اللطيف ابوعرقوب (2010)

Abstract

Natural gas has become an important source of energy in the world. Throughout the 19th century, natural gas was used almost exclusively as a source of light and its use remained localized because of lack of transport structures, making it difficult to transport large quantities of natural gas long distances. There was an important change in 1890 with the invention of leak-proof pipeline couplings, but transportation of natural gas to long distance customers did not become practical until the 1920s as a result of technological advances in pipelines. Moreover, it was only after World War II that the use of natural gas grew rapidly because of the development of pipeline networks and storage systems. Gas pipe lines are operated under steady state conditions. However, when transporting high temperature wet gas the gas getting cooled and heavy components condensate, Hence, pigs is usually are wanted to clean the pipe line to reduce pressure drop along the pipe In this study an existing pipeline was studied under steady and unsteady state. HYSYS and ProFES programs were utilized. Result show that gas temperature changes with time and distance. Results show that temperature and gas approach the ambient temperature at about 20 Km of pipe line length consequently, liquid phase volume fraction increase in first 20 Km of the pipe.
عدلي عمر احمد (2011)

Abstract

Normally the study and investigated of earth material from the view of their uses as embankment and backfill material has a great importance in earth woks. This research concerns the assessment of earth masses and their properties which related embankment and backfill suitability as well as providing a mixing methods to upgrade the unsuitable within the accepted standards. The objectives of this research could be briefed by the investigation of earth masses along the study area which is governed by the distribution of superficial deposits comprehensive laboratory testing of soil samples molding Andes properties classification testing proctor and California bearing ratio recognition of suit able and non suit able backfill soil enhancement of unsuitable soil by mixing with other suitable soil such as quarry dust provided by nearby quarry correlation analysis and economic feasibility the study area is located in east of Tripoli from Tajoura to Misurata . This study manly concluded that as long as the poorly graded soil (A3) is difficult to be compacted according to the engineering properties of such soil are enhanced certainly by mixing with good sailable materials such as quarry dust. This research also conduced that the compaction properties will be enhanced by mixing where the optimum moister content is needed at the increase of maximum dry density. This research provides procedure of mixing design and recommendations for the mixing to achieve better results.
عبد السلام محمد بحرون (2011)

Abstract

One of an important application the filtration system, whether filtering water or air. Cement plants in Libya which are located in residential areas, agricultural, or near water sources, so dust problem are solved by using innovative solutions in environmental dust collection. Dust collection system has proved. Highly effective especially after improving the mechanical properties of the candidate to add enhanced materials, this was an obvious performance of the filter. Carbon fiber has a global and multi-market increases mechanical properties in various industries. The addition of simple ratios of fiber carbon to polypropylene increases the tensile strength significantly, working to withstand the difficult conditions faced by the filter of high pressure and sometimes moisture, and other conditions that earlier discussed in this thesis. Addition of Talc has significant effect to improve the arrangement of atoms leading to nucleation effect. By using CF reinforce to PP to produce the appropriate filter. Fiber reinforced plastic are very costly but the ability to sustain a load without excessive deformation or failure. Specified filters for use in nearly any industrial application. By applying this design can minimize the negative impact caused by the industry and reduce these emissions to about 99%+ efficiency on 0.3-0.4 micron particulate.
فاطمة عمر حديد (2015)

Abstract

Recently more than 150 million tonnes of plastics were produced in the world. On the one hand, the consumption and production of polymers are increasing, on the other hand as landfill and incineration become more expensive and less accepted .The increasing amount of polymer wastes from them generates further mainly environmental problems. The recycling of plastic wastes is gaining increasing importance. Pyrolysis is one promising method for the treatment of mixed and contaminated plastic wastes. In this way the plastic wastes are converted into fuels or other valuable feedstock for the petrochemical industry. In present work catalytic cracking of waste plastics blend with HGO [Libyan gas oil supplied by the Zawia Oil Refinery Company boils in the range of 275-375Cº] was investigated using H-ZSM5and H-BETA. Reaction systems that were studied included high density polyethylene HDPE and polypropylene blend with HGO, reactions were carried out in one litre micro autoclave reactor under different conditions of weight, temperature and type of catalyst, The optimum conditions were 2.5% catalyst by weight of total feed stock, one hour, atmospheric presser and three temperatures selected 400Cº, 425Cº and 450Cº. The product distribution for the system [plastics and HGO] provided some good results high yield of liquid [gasoline] up to 210Cº, gases and small amount of heavy oils. Some analysis was used to qualify and quantify the product. The results from GC.MS analysis showed that the yield of gasoline (c5-c12) over H-ZSM5 higher than H-BETA. In case of 5%PP, 15%HDPE and 80%HGO over H-ZSM5 at 450Cº, 96% total conversion achieved. The result from TGA in the same case is 15% by weight. Also the theoretical calculations to quantify the produced gases after burring of waste plastic in rotary kiln reactor have been evaluated. it is found that the suitable ratio of CO:H2 to produce methanol is 7:1
بسمة محمود التونسي (2010)