المستودع الرقمي لـقسم الهندسة الميكانيكية والصناعية

Abstract

The aim of this study is to assess the wind energy potential and to compare Weibull and the Maximum Entropy Principle (MEP) distributions, with meteorological measured data. Dernah is selected site, which has good wind characteristics (seasonal, monthly and diurnal wind speed variations and wind direction variations), for possible wind energy applications. The data source is measured at an elevation of 40 m above the ground level for one year period (2003), and it is analyzed statistically. The functions of probability density and power density are calculated using the Weibull and MEP distributions. The Lagrangian multipliers of MEP distribution are estimated numerically at r values of 0 to 5 by using Newton Raphson, Simpson’s rule and Romberg’s methods. The MATLAB simulation is also applied for estimating Lagrangian multipliers. The verification of the results is also assessed by Maple software. The statistical analysis parameters based on wind speed and power density are used as the suitable judgment criterion for the distribution functions. It is found that for MEP distribution, the wind power (W/m2) 450, 395 and 407, are for the cold season, the hot season and for the year 2003, respectively. However, there is no significant difference of the presented peak values of the results in this study for Weibull and MEP distributions. Such result can be attributed to the fact that the average wind speeds were relatively high and the calm spells are about 7% in the year 2003 data.
جبريل يوسف الفيتوري (2010)

Abstract

The contribution of this thesis is to improve the understanding of acoustic dynamics in the audio duct with Helmholtz Resonator (HR). In this project, detail measurements of acoustic in a duct with HR induced loud–speaker at various frequencies have been carried out experimentally. Two-microphone technique have been used to measure the net acoustic power transmission in the duct downstream of HR along with the net acoustic power transmission in the duct without the HR. The acoustic wave signals are traveling in the duct as a plane wave, these waves are generated by a signal generator system with a know wave (sine wave). One of the microphone is located just before the neck–duct interface and the other microphone after the HR in the duct. Five type of necks ( perforated neck length 15cm, perforated neck length 10cm, cone–shape neck, Non- perforated neck length 15cm, Non-perforated neck length 10cm ) and three different material of the bottom wall of the cavity ( Teflon, water and cotton ) have been studied. The best results has a good advantage that by using (perforated neck length 15 cm and 4cm diameter because that reduction of noise has been reached 64% percentage and that value is the highest reduction from all experimenting.
إبراهيم فاضل عبد الحميد الزوي (2010)

Abstract

The contribution of this thesis is to improve the understanding of acoustic dynamics in the audio duct with HQ (Herschel-Quincke tube) is essentially a hollow side-tube that travels along a main-duct axis and attaches to the main-duct at each of the two ends of the tube. In this project the detailed measurements of acoustic in a duct with HQ induced by a loudspeaker at various frequencies have been carried out experimentally. Two microphones have been used to measure the net acoustic power transmission in the duct downstream of HQ and compared with the net acoustic power transmission in the duct without the HQ. Two types of HQ and three different ducts have been studied. The acoustic wave signals are traveling in the duct as a plane wave these waves are generated by a signal generating system with a known sinusoidal wave (sine wave). One of the microphones is located just before the HQ-duct interface and the other microphone after the HQ in the duct. Labview software is used to analyze the signals with a sampling rate of 44100s/sam and number of samples is 20000. This study makes an exhaustive understanding of power spectrum of two acoustic channels in the duct with and without HQ. The results show that there is a great potential for HQ tube system to attenuate the noise over conical and cylindrical sections. The sound attenuation on conical section with short HQ shows about 70% and that of cylindrical section a meager 47% at higher frequency. Further more the sound attenuation of cylindrical section with long HQ is occurred at low frequencies.
رضوان نجمي الكوني الشريف (2010)

Abstract

The static behavior of large deflection of plates is considered. The w-F governing equations for large deflection of plates are derived and Solved using Finite Element with Galerkin approach to calculate the static deflection and for parameter values which span the design space. An Incremental Iterative technique were used. The Galerkin Method was used to derive the element stiffness matrix and load victor. A three node- 18DOF Triangle Element was selected to calculate the nodal field variables. Two boundary conditions were considered, the simply supported and clamped plates. A well prepared program used for plates with small deflection,, Linear Problem,, was modified to handle the changes in the governing equations and apply the solution techniques. A good fit with previous published studies was found.
القاسم محمد كامور (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)

Most of organizations (both national and international) have struggled with many difficulties during the past decades due to many problems, creating a negative impact on the productivity and utilization levels of many institutions around the globe, and within Libya in particular. This paper presents the current role, relevance, trends and challenges with respect of quality management applications in educational field within Libya as a case study. It outlines an overview of the current state of art to show how in the face of growing global competitiveness quality at the levels of knower, knowing and known elements of educational system using unified field of all the laws of nature, are deriving the benefits of the quality techniques. The paper also investigates the current implementation levels of Total Quality Management (TQM) as a philosophy for improving the quality levels within some academic and training institutions within Libya. A survey methodology has been applied in this research where some findings from interesting case studies are presented to show the benefits of successful TQM implementations originally developed for manufacturing industry. The paper has also pointed to areas where senior managers within the surveyed organizations should take immediate actions to achieve effective and successful TQM implementations, thereby improving their position in this competitive marketplace. arabic 17 English 115
Rajab Abdallah Abdulqader Hokoma(1-2015)

فيما بعد arabic 201 English 0
رجب عبدالله عبدالقادر حكومة, علي الصويعي محمد البوزيدي, عبير المبروك عبدالغفار(6-2017)

شهدت مدينة طرابلس الكبرى قفزة نوعية في العديد من التعاقدات لتنفيذ مشاريع تنموية في البنى التحتية والاسكان وما يتطلب من مشاريع مرافقة إلا أنها في الآونة الاخيرة ومع بداية هذا العقد عانت أغلب تلك المشاريع من العديد من المشاكل، مما انعكس سلباً على كافة مراحل التنفيذ، لذلك تم القيام بهذه الدراسة هذه الدراسة للوقوف على أسباب التأخير في تلك المشاريع، وبالتالي العمل على إثراء المكتبة الليبية بالبحوث الميدانية التي تتناول موضوع أسباب التأخير في إكمال المشاريع الإنشائية، ويمكن أن تلفت الدراسة الحالية اهتمام الباحثين إلى معرفة الاسباب والتي أدت إلى التأخير في المشاريع، ودراسة كل سبب من ناحية ظروف حدوثه، وأهم النتائج المؤثرة سلبا على المشروعات، ونسق مساهمتها في التأخير، ومن خلال هذه الدراسة تم التعرف على الأسباب التي أدت للمساهمة في عرقلة تنفيذ المشاريع ببلدية طرابلس الكبرى، لأجل التركيز عليها مستقبلاً بهدف تفادي حدوثها. arabic 177 English 0
رجب عبدالله عبدالقادر حكومة, عبدالوهاب احمد دريبيكة(1-2019)