Digital Repository for University of Tripoli

Abstract

The contribution of this thesis is to improve the understanding of flame dynamics in the gas turbine combustor. The dynamic of diffusion flame or the flicker of a flame, as they are called in the research community is an important physical parameter associated with the characteristics of a combustion process. The flicker frequency of a flame reflects its oscillation of radiation, pressure and other characteristics, and plays an important role in flame structure, radiation field and energy efficiency. In addition, flickering frequency could be an indication of flame instability. It is therefore important to be able to measure the flicker of a flame in order to achieve an in depth understanding of the fundamental aspects of combustion processes and to develop a technique suitable for advanced flame monitoring in electrical power generation, gas turbine, boiler, and etc... To understand the phenomena related to thermoacoustic, a simple Rijke-type tube combustor was built and studied. Extensive experimental results, as well as theoretical analyses related to the Rijke tube is presented in this project. The results, attributable to both the analyses and the experiments, help explain all the phenomena affecting the acoustic pressure in the combustor. The conclusion is that there are three separate yet related physical processes affecting the acoustic pressure in the tube. To understand this parameter, a simple system was built and studied. Extensive experimental results are presented in this project to measure a flicker signal. In order to begin to understand what flicker parameter is, it was necessary to collect and analyze the light signal produced by light cell from burner which operates on diffusion flame, the chosen method for data collection was a light data acquisition system, the acquired light signal was then analyzed with Lab VIEW software, the software’s main feature is that it was capable of defining the light signal in many parameters, the most important of which were: power spectrum, cross correlation and the light wave shape. The power spectrum gave a concise presentation of the main frequencies which constituted the flicker signals, and their relative amplitudes. this was very helpful in determining the frequency of the diffusion flame (flicker signal).flame height and flame lift off also have been studied in this project. Finally applied this technique and all this Procedures at alkhoms power plant gas turbine combustor and then we compare the results with other technique like CCD camera and Photomultiplier we option the same results with cheaper devices
محمد عمران محمد (2013)

Abstract

The DC motor drives one of the high performance drives that still in competition in industrial application, because of its high performance, robustness, and its lower cost compared with AC motor drives.Due to its majority applications, the separately excited DC motor driver is studied. In order to improve, three independent controller design using classical proportional - integral – derivative, linear quadratic regulator and artificial neural network are considered.The Performance of these controllers has been verified through simulation based on MATLAB/SIMULINK software tools. According to the obtained simulation results, it is found that, an artificial neural network can achieve a better transient and steady state response in comparing to the other two design method. Consequently, the superiority of ANN controller over conventional proportional - integral – derivative is demonstrated this shows the superiority of artificial neural network controller over conventional and linear quadratic regulator controllers.
.زينب إبراهيم علي (2014)

Abstract

The foreign investment has been effected by many variables, which may impact the foreign investments, such as: laws and legislation promulgated inside the State, in addition to the expenditure of State on its different sectors, for instance, most of foreign companies are seeking to invest their funds in the States grant distinguished taxes incentives for investment in the same. As a result of increasing interest of the foreign investment significance and attraction of capitals to invest inside advanced or underdeveloped States similarly, the researcher saw the necessity of recognizing the attitude of foreign investment in Libya, starts from establishment of Libyan stock market and the extent of the impact of attraction of such investments or not. This study has been subdivided into five chapters, including preamble, which represents the general framework of the study, whereas second chapter discusses the theoretical framework of stock markets and their development, third chapter discusses the concept and determinants of foreign investment, fourth chapter tackles the whole indicators and investment policies in the Libyan economy, whereas fifth chapter talks about the practical study, includes outcomes and recommendations.As well as, the researcher relied in his study on the descriptive analytical methodology, which depends on collection and analysis of data and information related to foreign investments during the study period.The researcher also relied on reports issued by the general board for privatization and investment in Libya, in addition to report os Libyan stock market, in relation with foreign investments within it, as well as, reports issued by the central bank of Libya, notwithstanding the difficulty of obtaining the data, in addition to its lack of organizational aspect.
عبد السلام جابر عبده عبد الجواد (2011)

Abstract

The increased amount of electromagnetic radiation in the environment has increased the common concern over the possible health risks of wireless devices (e.g. mobile phone ). However, to minimize the amount of energy absorbed by the user is an advantageous from the technical point of view, as well. The reduction of power absorbed by the user not only reduces any possible health hazards but also makes the antenna more efficient. In this master’s thesis, interaction between modern mobile phone antennas and user is studied by using numerical full-wave EM methods. The thesis aims at improving, understanding how mobile terminal antennas behave in the vicinity of the user and how different numerical EM methods can be used to solve the interaction problem. The results give valuable information for antenna designers in order to design antennas which have low interaction with the user as possible. Furthermore this master’s thesis introduces a simple optimization technique to enhance the performance of planar inverted F antenna (PIFA) one of common modern mobile phone antenna in vicinity of user and reduce its effect on health.
محمد على المنصورى (2008)

Abstract

The industrial renaissance of the General Arab countries and the Libyan Arab country to make a special request to the elements and lounges stereochemistry of metal accessories and urgent, this renaissance that accompanied the technological revolution represented by using a computer and the diversity of its programs and the expansion of research methods and knowledge in various disciplines imposed on the engineers and industrialists and Almquaoliyn various categories of specialists, and that Ioakpo this international scientific development to be desired and decent level before this data. Where highlights of this research shed light on the installations steric mineral reviewing the characteristics of the analysis and structural design and methods of the basic implementation and relations of reciprocity between them and listed in a simple way and classified according to their constituent elements, to provide those interested in this field, among the main outlines of which need them in this special geometric way. Our goal in this research to the definition of mineral spatial installations, the basics of analysis, design and construction of major roads for this type of installations. Which we hope to contribute to simplify the development and understanding of the specific platform for this type of construction.
نبيل موسى الدليمي (2014)

Abstract

The internal auditing concept developed from being a profession for auditing financial accounts of the institution to become a profession that supplies the administration will all information and advice that serve the aims of institution. As a result of paying attention to environment in recent years, the issue of preserving environment has become one of the basic issues which have great oftentimes. In addition, the environmental auditing has become one of the important factors in the system of taking care of environment because it shares in avoiding penalties and fines that may encounter as a result of violating environmental laws and criteria by the institution.Accordingly, the researcher chose the study subject which is represented by study mg the way of developing the internal auditing office to play its role in auditing the environmental performance of the institution. Consequently, this performance of the institution. Consequently, this matter necessitates that the internal auditing office should audit the environmental performance of the institution to generate more comprehensive view on the probable environmental risks at the institution level.
عبد الحميد عاشور محمد المجدوب (2011)

Abstract

The objective of this study is to formulate a drilling cost model which incorporates the drilling parameters, encountered during drilling operation of the petroleum well. This model is coupled with the selected drilling rate model proposed by Bourgoyne & Young, in order to predict the bit rotating time utilized in this model. The new drilling cost model was formulated using actual drilling data collected from thirteen wells selected in three oil fields in Sirte Basin (Ghani, Zenad, and Ed Dib).The drilling engineer can use drilling correlations in the planning stages of a well to help evaluate various drilling parameters encountered during drilling operations in order to update the proposal drilling plan and to evaluate any deviations from original projections. The gathered information will help selecting the best completion strategies as well as gaining experiences in the drilled area which will be the basis for the planning of future drilling activities in the area.
عزالدين أحمد أحمد (2009)

Abstract

The problem of the study is summarized in that the profession of the external audit in Libya, is largely still depends on the way of experimental audit, that depends on controlling samples that based on experience and personal assessment, when performing audit operation which makes using the style of analytical review in the case of applying the controlling inspection conducts to less effective results by its using, when applying statistical inspection. In addition application of analytical review without the affirmation of data quality which being used, as base for application weakens the confidence of the resulted indices thus: there is need for using statistical Inspection when performing analytical review in spite of the role that can be played by statistical inspection styles in increasing the effectiveness of the analytical review, its using or its application, necessarily requires the availability of group from baisc requirements that are necessary to be used under the present reality for the profession. The aim of the study represents in, highlight the nature of analytical review and studying the intellectual frame work of statistical inspection, its importance, and its reflections, upon analytical review in audit and determination of statistical inspection requirments when performing the procedures of analytical review in audit, and studying the extent of using statistical inspection, as tool to Improve the effectiveness of analytical review under the present reality for external audit profession in Libya. The study targeted two baisc categories they are: External auditors working through the private audit offices located at Tripoli area, and accounting department auditors. The obtained data from the questionaire were analysed by descriptive analysis style In order to test the study hypotheses: the study reached to the result that the present reality of external audit profession in Libya is not feasible to the using of statistical inspection, when performing the procedures of analytical review in audit, and that because of there is no availability of personal requirements material requirements, and technical requirements, with enough degree that enables using statistical inspection style as tool, to Improve the effectiveness of analytical review, in audit according to the results that the study reached to.According to outcomes, that were reached by the study it is recommended that auditors should take more care of analytical review, Statistical inspection and conjunction between them in order to escort modern developments in auditing, through reviewing professional issuences, modern scientific references, and taking more interest in conferences and scientific seminars in the field of accounting, and auditing ,and through preparing training courses, and programmes in auditing in order to qualify auditors.
عبد المنعم مفتاح الكراتي (2012)