المستودع الرقمي لـجامعة طرابلس

Abstract

In this thesis, we present a method for the design of multidimensional digital filters. This method is based on the use of genetic algorithm (GA). GA algorithm is proposed to optimize the coefficients of magnitude frequency response of digital filter design. GA algorithm is used to minimize a cost function representing the difference between the frequency response magnitudes of an ideal and obtained digital filters. Two types of filters namely, Finite Impulse Response (FIR) and Infinite Impulse Response (IIR) are implemented.The digital FIR filter exhibits a wide transition bands and ripples in the pass band which are considered as disadvantages in digital image processing. Therefore, the only way to obtain a steep transition FIR is to use high order which translates to high cost. An alternative way to avoid high cost filters is to use IIR digital filters. Such digital filters can provide steeper transition bands with lower order than equivalent FIR digital filters. Although FIR digital filters have the disadvantages of high cost in term of hardware realizations, they have the advantage of stability and linear phase. Since IIR digital filters have infinite impulse response, they are prone to unstability. Linear phase which is easy to obtain in FIR digital filters is hard to come by IIR digital filters. The low cost and fast filtering make the IIR digital filters attractive. The proposed GA is utilizing for the design of stable IIR filter with near linear phase constraints. Experimental results are presented for 1-D and 2-D digital IIR filter. From the magnitude-frequency response, the convergence of the proposed approach will be able to obtain global minima in a faster time.
ميسون محمد الزرقاني (2010)

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

Laboratory experiment are conducted in the summer years (2010) to study the impact of adding a source of organic carbon (sawdust) on inorganic nitrogen in the soil Mixing (500 grams) soil texture sandy silt with rates by addition of compost poultry rates (0 - 15-30-60 ton/ ha), as well as the rates of carbon source sawdust (0.5-1%), where then mixed well with each other in order to become homogeneous, and placed in the pot and repeated three times each addition , just as the number of experimental units each experiment (180 experimental units), and incubated at room temperature while maintaining the moisture at field capacity gravimetric way through the different incubation periods, which is set in weeks (0-2-4-8-16 week) by using statistical decomposition split plot twice ( split-split-plot design) and determing the differences moral between averages using Duncan to isolate averages at the level of moral (5%) and analyze the results using a table (ANOVA), and then estimate the degree of interaction of soil (pH) and organic matter and nitrogen mineral and total ratio of carbon to nitrogen (C/N Ratio) during different incubation periods, The results showed fluctuations in the degree of interaction through different incubation periods were (pH) the highest value for (8.4pH) at the time of incubation (4-8 weeks) and the lowest value (7.8pH) at the time of incubation (16 weeks), the organic matter Tests showed an increase in organic matter with increased rates of adding compost and sawdust at the beginning of the period of incubation and decreases organic matter gradually with increasing duration of incubation (16 weeks) As a result of decomposition of organic matter by micro-organisms, while nitrogen mineral available results show an increased nitrogen available at the beginning of the period of incubation with increased rates of added fertilizer and organic sawdust With increasing time incubation fluctuation in the amount of nitrogen available Result of the succession of microbial occur collections and increasing the proportion of (C/N),The Results show in the amount of total nitrogen per transaction At the beginning of the period of incubation and after two weeks of incubation Results show increasing the amount of total nitrogen at a rate (60 ton / ha) and over a period of incubation at (16 weeks) results showed a decrease in the value of total nitrogen when treatment (60 ton / ha) and average (0.5%) sawdust, either carbon to nitrogen (C/N Ratio) Tests showed that the high proportion of carbon to nitrogen, with the rate Add compost and the proportion of sawdust at the beginning of the period of incubation with the passage of time and increase the period of incubation results show low (C/N Ratio) for each transaction with time as a result of mineral nitrogen liberate when the incubation period (4 weeks) and an increase of the period of incubation results show an increase ratio (C/N Ratio) for each transaction.
محمد الطاهر الفيتوري سالم (2013)

Abstract

Laser surface treatment of materials is one of the most effective methods of improving properties and performance of metallic articles. This technique proved its capabilities and advantages in comparison with other methods of surface treatment As an example, it has been shown that the distortion caused by this type of treament is at least one order of magnitude smaller than by that due to other techniques. Moreeover, laser beam is capable of reaching practically any point of the surface whatever it is narrow or difficult to reach by other techniques. The current work investigates the possibility of improving certain mechanical properties of both technically pure aluminum and A1-4o/oSi alloy, using ruby laser of 3 xl 05 W/cm2 power density. The surface of the investigated materials has been impregnated by SiC particles of varying size ranges, with or without firrther alloying of the surface with Titanium powder addition to the impregnated mixture. The laser treatment included coating one surface of each specimen of SiC particles by means of a binder added at a certain ratio (with or without Ti additions to the mixture). The coated surface was then subjected to the laser beam, which melted a layer I OO-150Jilll thick. Due to hydrodynamic effects the melt mixes with SiC particles and dissolves some or all of the added Ti and rapidly solidifies forming a thin layer distinct in properties from the original surface. Two groups of specimens were used in this study. The first group was treated by impregnating SiC particles of one size range with or without Ti-additions. Various numbers of laser pulses have been applied increasmg in a geometrical progression (1-2-4-8 pulses). These specimens were used for the study of the effect of varying: 1) the chemical composition of the substrate materials ;2) the number of laser pulses :and 3) the effect of Ti additions to the impregnating mixture on the microstracture and microhardness of the treated zones. The specimens of the 2nd group were coated by a square network of laser treated zones each 1.5mm in diameter. These specimens have been used to study :1) the effect of the chemical composition of the substrate material ;2) the size of the SiC particles and 3) the effect of Ti addition to the mixture on the wear perfomance of the treated specimens. Identical specimens have been used to determine the solubility of Si into the aluminum phase during the test by means of x-ray diffraction. This dissolved Si is partly responsible for the increase ID microhardness and wear resistance of the investigated specimens. The results show the positive effect of the applied treatment on the properties and preformence of technically pure AI and A-4%Si alloy. The materials microhardness within the treated zones has been increased by a factor of 2.7 and 2.4 for pure Al and Al-4%Si substrates, respectively. The microstructure of the treated zones became more homogeneous and the penetration of SiC particles into them has been increased with increasing the number of the applied laser pulses. The wear resistance of pure Al has been increased by a factor of 73.6 due to laser assisted impregnation, while that of AI-4%Si by afactor of 42.5. Wear resistance was found to increase with I) Si addition to the base metal; 2) Ti addition to the impregnated mixture, and 3) increasing the SiC particle size. This thesis is a part of a wider study that deals with surface treatment of Al and AI-Si alloys undertaken in our laboratry. Such study proved how effective the laser alloying and impregnation of such alloys in improving some of their mechanical properties which are important in industrial application, especially in internal combustion engine design.
أسماء عبد الرزاق وهرة (2002)

Abstract

Libyan cities have experienced a period of rapid urban expansion in the past decades. Urban growth as an example has been the focus of urban researches for a long time. Due to the complexity of the urban growth process, it’s very difficult to model urban growth using traditional urban models. Recently, urban researches are keen on a new technology, Remote Sensing. Remote Sensing technique was applied in many aspects of life, due to ability of covering and representing the real world around us. In urban research, field researches set up many applications to simulate the urban phenomena such as sprawl process, landuse change trends, landcover...etc. Remote sensing technology helps to extract and organize the data about such phenomenon. In addition to understand their spatial relationships, and provides a powerful means to planners and decision makers for analyzing and information about a place or a phenomenon. This will have great impact on the quality of the decision-making. The study uses Spot 5 images, topographic maps which derived from aerial photographs for the year 1980. The remote sensing image interpretation and change detection to review the urban expansion for the study area in (1980 and 2009).Spot satellite image of 2009 and Landuse maps1980 will be used to derive information on urban land use in the study area. The visual interpretation is used to extract landuse. The mutual use of Remote Sensing (RS) and Geographic Information System (GIS) describes the overall physics changes of the study area. This effort can be considered as an application case in this field (RS-based town planning information system), where this thesis show how that system can be useful of using this technology and supporting the sector by developing a model that can support the process of planning and maintain what remained of the agricultural lands to prevent them from encroachment by the urban growth.
حسين علي أحمد زيدان (2010)

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)