المستودع الرقمي لـكلية الهندسة

Abstract

Voice over IP (VoIP) uses the Internet Protocol (IP) to transmit voice as packets over an IP network, like the Internet, Intranets and Local Area Networks (LAN). Here the voice signal is digitized, compressed and converted to IP packets and then transmitted over the IP network. However, at the receiving end, some packets may be missed in its way due to network congestion. This packets loss degrades the quality of speech at the receiving end of a voice transmission system in the IP network. Since the voice transmission is a real time process, the receiver cannot request for retransmission of the missing packets. High speed networks provide real time variable bit rate service with packet loss requirements. The burstiness of the correlated traffic makes dynamic buffer management highly desirable to satisfy the Quality of Service (QoS) requirements. This thesis presents an algorithm to improve and optimize the Adaptive Buffer Allocation Scheme to deal with input traffic based on loss of consecutive packets in data streams and buffer occupancy levels. Buffer is designed to allow the input traffic to be partitioned into different priority classes, and based on the input traffic behavior it controls the threshold dynamically. This scheme allows input packets to enter into buffer if its occupancy level is less than the threshold value for priority of that packet. The threshold is dynamically varied in runtime based on packet loss behavior. The performance evaluation is carried out using simulation and is carried out for two and multiple priority classes of the input traffic "real time and non real time classes". The simulation results show that the Modified Adaptive Partial Buffer Sharing (ADPBS) has better performance than Adaptive Partial Buffer Sharing under the same traffic conditions.
اسماء احمد الكيش (2010)

Abstract

Wind turbines are the means of converting wind energy into electrical energy. It is not unexpected that certain brands of horizontal wind turbines are optimally designed for certain wind speed regimes prevailing at certain sites. It has been the objective of this study to find out whether it is possible to design a wind turbine that is more suitable for a site of lower annual mean wind speed such as the western coast of Libya. In achieving this objective, use was made of a typical wind turbine aerodynamic design and performance analysis procedure together with actual wind speed data recorded at the city of Misurata.Based on the annual wind energy yield obtained from different designs of wind turbines having different rated wind speeds and different blade design tip speed ratios, this study indicates that the decrease of the rated wind speed leads to a continuous increase of annual energy yield as well as an increase of the cost of the wind turbine. Therefore the optimum value of rated wind speed for this site may only be determined as a compromise between added wind energy yield and added cost. Moreover, for any given rated wind speed this study indicates that a blade design tip speed ratio equal to six seems to be the optimum value for the given site.
محمد على نايلي (2015)

Abstract

: In this study, a three dimensional computer code based on the so called SIMPLE algorithm (which stands for Semi-Implicit Method for Pressure-Linked Equations) developed by McGill University-Montréal-Canada is used for the numerical solution of a laminar fluid flow and heat transfer of impinging four jets in the presence of crossflow with constant temperature boundary condition on the impingement surface. The governing equations solved by the computer code are the continuity equation, three components of the momentum equation and the energy equation. The finite volume method is adopted for the discretisation of the governing equation. In the computer program, the finite difference equations are solved via the primitive pressure-velocity approach where the hybrid difference scheme, which is a combination of the central and upwind differences, is used to represent the convective and diffusive fluxes over the control volume surfaces. The results obtained show that in general, for multiple jets, the induced and imposed crossflow have significant effects on both the flow and temperature fields near the impingement surface. A strong crossflow deflects the jet and prevents it from impinging on the surface resulting in lower heat transfer rates and hence lower temperatures difference.The results also show that reducing the jet separation distances causes an increase of the temperature of the flow, and hence better cooling of impingement surface.
إبتسام عمارة (2008)

Boot contracting and its useability scope in implementing construction projects in LibyaThe development of construction projects is considered among the most important indicators of development and progress of society. Numerous project areas that have witnessed development in Libya in recent decades, including construction and building, whether infrastructure projects, productivity or investment projects. As the engineering projects department is one of the most important elements of the success of the project, and is therefore important to develop contractual aspects associated with the urban development stages in the country. Despite, the role posed by construction projects in our country, but they face through their various stages of implementation to a number of problems that may not be addressed in regulations and legislations currently in force, and this call to think of changes or additions to these systems, such as the proposal of new contractual patterns that contribute to the implementation of these projects in the best possible way. Therefore, this research aims to propose concession contracts, which are a range of patterns differ in application depending on the type of project contracted, and these contracts share the notion that they are projects owned but public authorities and funded from outside the general budget, the type of contract selected is the BOOT (Build, Operate, Own & Transfer) contract to be the topic of this study. The stage approached by Libya of the large urban development through the implementation of large construction projects requires the preparation of budgets and human resources, equipment, materials and machinery, and the question before us is whether the implementation requirements available to the general implementation bodies; that includes budgets or human work staffs of engineers, supervisors and workers and suppliers, as well as operators and administrative officials allows for the implementation of these projects? The importance of this research lies in the opening of a broad area both to domestic and foreign investments, and give the opportunity for the private sector to participate in the anticipated urban boom in the use of concession contracts (BOOT (Build, Operate, Own, Transfer)), and these promote the public owner of the project to grant the concession right to a private entity to implement the project and this entity is known as the concession authority, it implements the project and has temporarily ownership of it and operate it for a period of time known as concession period, and that is determined in the contract and at the end of the period the whole facility is delivered fully operational and without any expenses to the public authority the original owner of the project, and the financier could recover the costs of the implemented project through its operation and granting the good investment returns. This research adopts the methodology of the analysis of a sample of administrative contracts to identify the problems encountered in construction projects, causes and classification, and the study has been supported by information compiled by distributing a questionnaire in addition to interviews with the elements of the study sample that was represented in a group of engineers and experts who have been carefully selected to represent most of the public authorities the owners of the projects as well as advisory bodies, after the data collection through methods mentioned above, which is the practical side of the study, information was also obtained through the search in scientific reference sources concerning concession contracts, definition, use and features, etc. this is the theoretical side. It has been analyzed by statistical analysis methods and reach recommendations and proposals to help use concession contracts as a solution to some of the problems facing construction projects in Libya, also reach the preparation of a proposal for a principle concession contract model that can be used by stakeholders in their contracts, with the recommendation to keep research in this field to overcome some difficulties that might result from using this type of contract.
هند أمين شقليلة (2008)

It has become important for higher education institutions to seek accreditation of both types if they are to improve and to achieve continuous development in the performance of their mission and compete in the labor market or to satisfy the customer through the application of standards of academic quality. The accreditation has become a key demand of the Foundation for acquiring financial support and as a feedback to the continuous improvement in academic quality. It became clear to the researcher that there is a study problem which is summarized in the low level of graduates as a result of non-application of accreditation standards accurately, which results in non-application of quality management system effectively in the Faculty of Engineering, University of Tripoli, leading to damage to the technical and hence economic to certain institutions, and therefore The study hypothesis was developed which can be summarized in the problem described above. To make a field study the focus was on the Libyan Quality Assurance Center questionnaire. Three categories of faculty community were chosen representing the workers of the Faculty of Engineering, University of Tripoli, who are best to answer the questions in the questionnaire devoted to the field study. The categories are namely; teaching staff members who have sufficient experience which makes the researcher trust their responses as they are knowledgeable of all aspects of the administrative and financial issues of the faculty. The second categories are the engineers, and the third categories are the administrators. The answers of these three categories were studied using the gap analysis according to the qualification and accreditation standards required by the Libyan Quality Assurance Center. Statistical analysis and evaluation reports were prepared for the institution. Results showed marked distinction and preference for the first category’s answers (teaching staff members). This is due to the experience and the higher academic degree that this category has in comparison with the other two categories. On the light of these results test the hypothesis of the study was tested and proved. The acceptance of a null hypothesis being that the Faculty of Engineering, University of Tripoli will not get the accreditation because of the wide gap in the number of the topics which needs to be corrected. Therefore several points were extracted upon which some recommendations were reached represented in a number of requirements which should be available to provide a suitable environment for the application of academic quality standards for qualification and accreditation. These requirements include; the commitment of the faculty management to apply the criteria of academic quality for qualification and accreditation. The formation of a working group to improve the quality of faculty focusing on achieving the needs of the customers. Giving attention to training and development for employees of various levels and good planningwhich helps to apply the standards of academic quality. Also adding some procedures’ quality in the institution and spreading the culture of quality.
خالد امحمد محمد (2011)

أصبح الاهتمام بالتعليم والتدريب التقني والمهني كبيرا لما له من دور هام في زيادة مستوى الإنتاجية وتحسين القدرة التنافسية لمختلف أنواع وأشكال المنتجات مما يساهم في زيادة الدخل الوطني وتحسين مستوى معيشة الأفراد. وقد تزداد أهمية التعليم والتدريب التقني والمهني في ظل المتغيرات الدولية والتطورات التقنية والتكنولوجية السريعة التي يمر بها العالم وما ينتج عنها من تغيرات سريعة في المهن ووسائل وأساليب العمل الأمر الذي يتطلب اتخاذ الإجراءات المناسبة لتطوير منظومة التعليم التقني والتدريب المهني والفني باستمرار وفقا للمستجدات والتطورات العلمية من أجل توفير العمالة المدربة القادرة على التعامل مع التكنولوجيات الحديثة والحفاظ على التوازن بين مخرجات التعليم التقني والتدريب المهني والفني والاحتياجات الفعلية لسوق العمل الليبي.ولكي نتمكن من مواجهة تلك التحديات الآنية والمستقبلية، فإن مجتمعنا في حاجة ماسة وملحة لشباب وأيدي عاملة تتميز بالقدرة على العمل باستقلالية ويتمتع بقدرات إبداعية ورغبة قوية في العمل، ويستند إلى قاعدة من المعلومات والمهارات التي تتمشي مع المستويات العالمية المناظرة طبقا لحاجة أسواق العمل المختلفة.و ليس ثمة اختلاف على أن المدخل الرئيسي لأية محاولة تسعى لتحسين الأداء وضمان جودة المخرجات في التعليم التقني والتدريب المهني والفني يعتمد على مفهومي التقويم وقياس كفاءة وفاعلية النظام التعليمي والتدريبي. وبذلك نضمن إنجاز وتحقيق مستهدفات منظومة التعليم والتدريب المرحلية والإستراتيجية ومعالجة السلبيات والصعوبات التي قد تواجه هذه المنظومة. نتناول في هذه الدراسة تقييم لأداء مراكز التعليم التقني والتدريب المهني والفني في الجماهيرية والتي تحرص على أن تكون متميزة وتساهم في تطوير المجتمع المحلي وذلك من خلال التفاعل المستمر مع مختلف قطاعاته وتوفير الكفاءات المتخصصة لتطوير الاقتصاد الليبي . ولتقييم هذه المراكز تم تصميم واختبار استمارة استبيان للعاملين فيها (أمناء الأقسام، أعضاء هيئة التدريس, المدربون, المتعاونون، الفنيون, الإداريون) وذلك لتحليل إجابات وبيانات المستبينين لعمل الإحصاءات اللازمة لاختبار معايير محاور التقييم، ثم استخدام هذه النتائج في التحليل البيئي(swot) لهذه المراكز لتحديد نقاط القوة ومحاولة تعزيزها، ونقاط الضعف ومحاولة الحد منها والتغلب عليها.وقد أظهرت النتائج من خلال إجابة المستبينين بان المحور الخاص بضمان الجودة والتحسين المستمر هو نقطة الضعف لهذه المراكز .وان المحور الخاص بالشئون المالية هو نقطة قوة لهذه المراكز ،وهذا يعطى مؤشر بان الإمكانيات المادية المتاحة من قبل الجهات المعنية على مستوى جيد ويجب استغلالها بالشكل الأمثل.وخلاصة القول واعتمادا على نتائج هذه الدراسة فأن المؤسسات التعليمية/التدريبية التي تم دراستها تحتاج إلى تطوير وتحسين أداء العملية التعليمية /التدريبية بها كل حسب نتائج التحليل البيئي لها وبناء خططها الإستراتيجية والتنفيذية.

Abstract

Technical and vocational education and training plays a vital role in the economic development of any country, because it is expected to be the main supplier of skilled work force to the labour market; and hence improve productivity and competences, and which leads to an improved standard of living. Supplying the labour market with qualified work force that can contribute positively and effectually and perform the tasks expected from them in the varies economic sector of the country is not an easy task taking this consideration he changing needs in height of the festally changes and growing demands caused by globalization and modernization therefore, it is essential that the Libyan technical and vocational centres are assessed and evaluated based an their existing faculties and programs to explore whether the are capable of graduates technical staff that can meet the local labour market needs.This study is consumed with evaluating and assessing the current situation in the higher technical of vocational institutes in Libya through questionnaire specifically prepared to gage the generous management teaching and technical staff , administration staff and part time teaching staff. The data collected was analyzed using standard statistical methods such as swot analysis which gives clear ideas about the strengths, weakness, opportunities and treats. The results of this survey study shared that there is an urgent need to set up Quality assurance system to improve performance, and that the financial situation and tending of must institute is adequate.The study calculates that the highs technical and vocational institutes in Libya need a strategic plan to set up proper Quality assurance and accreditation system that can put forward standards and follow their implantation to improving the quality of graduates and enable them to contribute positively and effectively in the local and perhaps regional labour markets.
فيروز جمعه عمر ابوبريق (2011)

إن اعتماد أدوات السيطرة في ضبط الجودة هو السبيل الوحيد للوصول إلى النجاح وارتقاء سلّم القمة للوصول إلى التمايز في الأعمال، وبناءً على ذلك يأتي هذا البحث لتحليل أدوات السيطرة النوعية ( Quality control ) المطبقة في شركة الزاوية لتكرير النفط ولاسيما إدارة مصنع الزيوت، والتعرف على أنماط العمل الإداري في بيئة العمل الداخلية. إن اعتماد معايير وطرق القياس وإصدار المواصفات القياسية لمختلف المنتجات التي يعنى بإنتاجها مصنع الزيوت يسهم بتطوير ورفع الكفاءة الإنتاجية ومستوى الجودة للمنتجات من خلال فعاليات تأكيد الجودة ، وكذلك الحد من التالف من المنتج أو ذات الجودة المنخفضة من خلال فحص ومراقبة النوعية باعتماد معايير التحكم بالجودة من خلال أدوات السيطرة النوعية.ولقد وجد الباحث من خلال اطلاعه وزياراته المتكررة لبيئة العمل في مصنع الزيوت بقسم تصنيع العلب المعدنية وقسم التعبئة، ومن خلال المناقشات المستمرة أنّ هناك هدراً وتلفاً في الإنتاج، والذي يعزى لسبب رئيس وهو غياب دور وحدة السيطرة النوعية وغياب الأساليب الحديثة في ضبط الجودة، وعدم تطبيق تلك الأساليب في المصنع قيد البحث، كل ذلك دفع الباحث إلى دراسة تلك المعطيات.إنّ أهمية هذا البحث تكمن في تأكيده على أهمية استخدام أدوات السيطرة النوعية في عرض الواقع الفعلي لسير العمليات الإنتاجية، وكشف وتشخيص مواضع الخلل والعمل على علاجها وتفاديها مستقبلاً.وقد توصّل الباحث إلى جملة من النتائج ومن أهمّها: أوضح البحث عدم تطبيق أدوات للسيطرة النوعية على عملية الإنتاج وإنما تطبيق أساليب السيطرة والرقابة على زمن العمل.عدم وضوح مفهوم أدوات السيطرة النوعية لدى العاملين بالمصنع.أنّ الدورات التدريبية التي تعطى للمنتجين من حين إلى آخر هي دورات لاستمرار اكتساب الخبرات القديمة وليس دورات استخدام أدوات السيطرة النوعية.عدم وجود قسم متخصص بالسيطرة النوعية على الإنتاج بالمصنع.وأهم التوصيات التي توصل إليها الباحث هي:ضرورة إنشاء قسم متخصص بالسيطرة النوعية على الإنتاج بقسمي التصنيع والتعبئة في المصنع.التأكيد على إدارة مصنع خلط وتعبئة الزيوت بشركة الزاوية لتكرير النفط بضرورة تعيين عاملين ذو مؤهلات علمية جامعية قادرة على تطبيق أدوات السيطرة النوعية على الإنتاج.ضرورة إقامة دورات تدريبية متخصّصة بأساليب السيطرة النوعية وطرق استخدامها، بحيث تتضمن تلك الدورات مفهوم أدوات السيطرة النوعية لدى العاملين وبيان أهميتها.تشجيع العاملين بالمصنع على المشاركة بالدورات التدريبية المتخصصة بمجال السيطرة النوعية على الإنتاج من أجل تحسين جودة الإنتاج.
فتحي الطاهر شلغوم (2008)

التصوير الطبقي ذو المعاوقة الكهربائية (EIT) هو تقنية تسمح بإعادة بناء صور المقطع العرضي المتعلقة بالمعاوقة الكهربائية من خلال مجموعات مقاسه من سطحها، الدافع الرئيسي من تطوير التصوير الطبقي ذي المعاوقة الكهربائية(EIT)هواحتمالية تطبيقه في مجالات التصوير الطبية، وكما هو معروف فأن النسيج الحيوي له مدي معاوقة كهربائية واسع والعديد من الأحداث الفسيولوجية محسوبة بتغيرات المعاوقة الكهربائية، و موصلية نسيج جسم الإنسان فيها اختلافات كبيرة، لذا يجب أن تعطي صور الموصلية مقارنة عالية بين الأنسجة الناعمة. وتعتمد تقنية التصوير الطبقي ذي المعاوقة الكهربائية على إعادة بناء توزيع الموصلية في جسم الإنسان، وذلك من خلال القياسات الخارجية التي يتم قياسها عند تمرير التيار خلال المجسات الموجودة على الجسم والتيار المار، والجهد المقاس يعتمد على الموصلية المراد إيجادها، وتهدف كل خوارزمياتِ وإعادةَ البناء إلي تَقليل الأخطاءِ، والحصول على صور ممتازةِ. إعادة بناء الموصلية في التصوير الطبقي ذي المعاوقة الكهربائية (EIT) تعتبر مشكلة، وبشكل عملي تحل هده المشكلة ببعض طرق التنظيم أو الفرضيات المطبقة لتحسين نوعية الصورة.للحصول على أفضل بناء صورة ممكنه للتصوير الطبقي ذي المعاوقة الكهربائية تم في هذا العمل إجراء مقارنة بين العديد من طرق التنظيم وكانت معتمدة على تعديل النسبة بين أكبر وأصغر القيم الصغيرة والقريبة للصفر داخل مصفوفة الحساسية وتم تطبيق ذلك في طريقة جديدة.كما تم في هذا العمل أيضاً تطوير طريقة جديدة تتعلق بالتصوير الطبقي ذي المعاوقة الكهربائية وتسجيل الصورة و تم الحصول على المعلومات الكاملة في الصورة الجديدة.

Abstract

Electrical Impedance Tomography (EIT) is a technique which allowscross-section images related to the local electrical impedance within an object to be reconstructed from sets of measurements made on its surface. The main drive behind the development of Electrical Impedance Tomography (EIT) has been its possible application in medical imaging, as biological tissues are known to exhibit a wide range of electrical impedances and many physiological events are computed by electrical impedance changes. The conductivity of the human tissue has large variations so images of the conductivity distribution should give high contrast of soft tissues. In electrical impedance tomography (EIT) the conductivity distribution is reconstructed from measured boundary potential when current sources are applied to the boundary of the object. Both internal current paths and potential distribution depend on the unknown conductivity distribution. All considerations of the reconstruction algorithms aim to minimize the errors, and to obtain quality images.Reconstruction of the conductivity distribution in electrical impedance tomography (EIT) is an un-determined and ill-posed problem. Typically requiring simplifying assumption or regularization methods to improve image quality.To improve the system’s conditioning and to determine the best image reconstruction in electrical impedance tomography (EIT) several regularization methods in this work are compared, and based on modification of the ratio between the largest and the smallest non-zero singular value of the sensitivity matrix, a new method has been developed.Also in this work a new method concerning electrical impedance tomography image registration has been developed and the full information contained in the new image can be obtained.
زينب احمد العزابى (2008)