المستودع الرقمي لـجامعة طرابلس

Abstract

Pouring of concrete underwater is necessary in the implementation of most in-shore, and off-shore structures. The pouring of underwater concrete is considered as a challenge for engineers, even during the design stage or during implementation and supervision. This is due to the fact that many precautions must be taken for the success of casting process. The most important precaution is to protect the fresh concrete during the casting process from the water to avoid the risk of washout of cement past and segregation of aggregates. Concrete can be placed underwater successfully though good design of concrete mix, and through choosing the most suitable method for placing of concrete. There are new techniques for underwater concreting such as grouted aggregate which is known as two-stage concrete (TSC) method which, as the name implies, consists of filling a form work with the coarse aggregate and then injecting the grout to fill the voids through pumping tubes extended to the bottom of the form. The main objective of the thesis is to present the capability of pouring the concrete underwater by using (TSC) method. A laboratory model was prepared and visually investigated and tested by extracting core samples, performing compressive test, tensile test and using ultrasonic pulse velocity test. From the obtained results it has been observed that, it is possible to pour concrete underwater by using two stage concrete in successful way, and it is recommended to develop this research by using different water cement ratios and cement sand ratios to get the optimum mix design and also, different types of aggregates which are available in local quarries.
منال فاروق النجار (2010)

Abstract

Behavior of constant thickness circular plates under axisymmetric uniform loading and for different edge boundary conditions may be obtained analytically, but for the case of variable thickness and transverse shear effect is usually difficult to follow analytically. Since the numerical analysis has become an essential tool in engineering mechanics, where the use of numerical methods enables the engineer to expand his or her ability to solve practical design problems, where the engineer may now treat real shapes as distinct from the somewhat limited variety of shapes amenable to simple analytic solution. That is why developing an appropriate numerical analysis becomes a more suited procedure to solve such problems. The standard stiffness procedure of finite element method may encounter some difficulty in formulation when dealing with both cases of variable thickness and transverse shear effect. The usually followed procedure is to utilize ring elements of constant thickness and increase the number of elements to reach an accurate solution. Mixed finite element formulation utilizing curved ring element with linearly varying thickness as well as considering the shear effect has proved to be successful to obtain accurate results for shells of revolution with small number of elements, due to the fact that the mixed formulation allows for nodal values in the form of global displacement components (ur, uz) and bending moment (Mr, M) as field variables, where second order polynomials may be used allowing for shear deformation effect to be considered as a function of moments and does not require higher order polynomials.
ايناس عبدالمولي المصراتي (2009)

Abstract

An atomic bomb or any normal bomb may be exploded in the air or at or near the surface of the earth. The medium in which the bomb is burst determines to a large extent the relative magnitudes of the various damaging effects. The detonation of an atomic weapon releases a largeamount of energy in a fraction of a second. During this time the bombcomponents are volatilized into a sphere of hot compressed gas at a temperature of millions of degrees and a pressure of the order of hundredsof thousands of atmospheres. This phenomenon is characterized by an instantaneous and very rapid rise to a maximum pressure followed by a decline to sub-atmospheric pressure and then a gradual return to normal pressure. In this thesis the definitions and types of explosives and explosions are studied, effects of the different types of explosions are explained, transition of atomic air blast pressure from center of explosion to buildings are presented, determination of atomic air blast loading on buildings is studied as well.
أحمد عبدالرحيم سليمان (2008)

حيث تكمن أهمية الدراسة في إن دراسة اتجاهات مدراء المدارس نحو إقامة الأنشطة الرياضية الداخلية ومشاركة مدارسهم في الأنشطة الرياضية الخارجية لأنها تعتبر في غاية الأهمية، ومن خلال هذا يمكن التنبوء بإحداث تغيير في سلوكيات الذين يرون أن النشاط الرياضي عمل زائد عن الحاجة، وإلي ضرورة الاهتمام بالأنشطة. الرياضية الداخلية والخارجية حثي يمكن تحقيق مستوى أفضل من اللياقة البدنية والصحية للتلاميذ وإكسابهم المهارة الحركية التي تسمح لهم باستثمار وقت فراغهم. ونتائج هذه الدراسة سوف تمكننا من التعرف على الاتجاهات الموجودة لدى مدراء المدارس نحو الأنشطة الرياضية الداخلية والخارجية، فالاتجاهات الإيجابية تعني الميل الإيجابي نحو الاهتمام بالأنشطة الرياضية، وإن الاتجاهات السلبية الموجودة لدى مدراء المدارس تجعل الأنشطة الرياضية الداخلية والخارجية دائماً في هبوط مستمر. ومن خلال عمل الدارس كمدرس في احدي المدارس التي تعاني من هذا التقصير تجاه الأنشطة الرياضية، لاحظ عدم متابعة مدراء المدارس أو اهتمامهم بالأنشطة الرياضية الداخلية والخارجية بالمجال المدرسي في توجيه وتنشيط العملية التعليمية والتربوية للتلاميذ وإكسابهم القدرات الحركية والمهارية وإشباع حاجاتهم وميولهم وتشجيعهم والاهتمام بهم من قبل المدراء ومعلمي التربية البدنية والرياضية، حتى يمكن مساعدة الطلاب على النمو الشمولي المتزن من خلال التغلب على الدور السلبي نحو النشاط الرياضي، وبذلك يتاح لأكبر عدد من الطلاب المشاركة في الأنشطة الرياضية بكفاءة عالية .الاستنتاجات: في ضوء الأهداف وتساؤلات الدراسة والتحليل الإحصائي لإجابات العينة تم استخلاص الآتي:وجود مستوي جيد من الاتجاهات الإيجابية في رأي وفلسفة مدراء المدارس نحو الأنشطة الرياضية الداخلية والخارجية تمثلت بشكل عام وفقاً لإجابات العينة وهى كا لآتي:الأنشطة الرياضية تؤدي بشكل إيجابي إلي اكتساب صفات خلقية واجتماعية حميدة .كما أنها تعمل على اكتساب معلومات وثقافات رياضية حول أهمية الرياضة في التنمية الشاملة للنشءالأنشطة الرياضية تعمل على تنمية الانتماء وحب الوطن، كما أنها تعمل على اكتساب اتجاهات وميول واهتمامات إيجابية . الأنشطة الرياضية تساهم في تحسين الحالة القوامية واللياقة البدنية واستثمار أوقات الفراغ لدى التلاميذ. ضرورة الاهتمام بالأنشطة الرياضية واعتبارها جزءا مكملا أساسيا من المنهج الدراسي بالمدرسة.عدم رضا المدراء بنقص الإمكانات والأدوات والملاعب بالمدارس مما قلل من إقامة الأنشطة والمشاركة فيها بفاعلية .التأكيد على ضرورة أن تكون الأنشطة متنوعة وفاعلة إن توفرت كل الإمكانات خاصة البشرية المتخصصة لتنفيذها للاستفادة منها بشكل حقيقي .
المرغني ميلود مانع قنان (2015)

Abstrac The equivalence relation has many important uses in the development of Mathematics. Including what is known and some are used in research and new Studie The aim of this study is to highlight some of the applications of equivalence relations in important fields such as the development of a semi-metric space (seminorm) to a metric space (normed space) as well as some of the uses of equivalence relations in measure theory, particularly in the definition of important spaces such as. In addition, there are important applications in algebra particularly in group theory and matrices. As well as in information and rough sets. Equivalence relations may identify somewhat singular points and their Equivalence class as a single point in the quotient space. The importance of equivalence relations is unlimited. For instance, whenever an incomplete metric or normed space is constructed in applied or the theoretical science, the equivalence relations shows that there is a complete space which is the closure of the incomplete space. Precise statement and illustrations are included.
امل عبد الله طربان (2015)

Abstract

A technique for mixed–languages program is introduced to mix C and FORTRAN. programming languages. This technique enables the programmer to develop programs. composed of different code sections each written in either C or FORTRAN. Each. Section can access and use the variables decleared in other sections. The variables. Decleared in C sections can be used in FORTRAN sections. This process in which a data variable is declared in a program section of a certain. Language and used in another section of another language is given the name "Data Variable Emigration". A preprocessor is designed to read the mixed source program, separate the code. Sections in different files and determine the emigrated variables and define them by the syntax of the language they emigrated to. Then the preprocessor send the sections files to the compilers to get the object files and send these files to a common linker to produce one execution file.
رحاب عبد الله رجب بن عبد الله (2009)

Abstract

Applications of cooperative multicast communication techniques for emerging broadband multimedia services, such as Internet Protocol TV (IPTV), over WiMAX air interface have an important and attractive feature of reducing the network resource consumption, by broadcasting the data once to multiple users (e.g., TV channel group members) simultaneously independently of their number, using a common shared downlink channel. But users distributed around the cell face different channel conditions due to fading, user location, mobility, and other related characteristics. Several schemes were reported in the literature that attempt to introduce cooperative multicasting reliably and efficiently, some of which utilize subscribers with good-channel as relay agents (RA) to provide coverage for subscribers with bad-channel but fail to consider the huge amount of energy consumed in the process. In this thesis, we propose energy-efficient cooperative multicasting schemes by properly selecting RAs based on their location, channel condition and coverage. By exploiting the channel state information (CSI) and the location based service (LBS) techniques, protocol based on nearest neighbor, transmission distance and subscriber-subscriber interlink instantaneous CSI were proposed and implemented in order to achieve much improvement in the system performance. The number of RAs was varied in accordance to channel conditions and treated on a frame-per-frame basis. This approach considerably reduces the amount of energy consumed as proven by analysis and simulation models, providing a lower cost coverage solution with no dereliction in achieving high throughput for all group members.
سارة مفتاح الربيعي (2010)

Abstract

As user applications continue to drive network growth and evolution, demand to support different types of traffic is also increasing. Different types of applications with differing network requirements create a need for administrative policies mandating how individual applications are to be treated by the network. Network traffic from business-critical applications must be protected from other types of traffic. Requests from business-critical and delay-sensitive applications must be serviced with priority. The employment and enforcement of quality of service (QoS) policies within a network play an essential role in enabling network administrators and architects to meet networked application demands. QoS is a crucial element of any administrative policy that mandates how to handle application traffic on a network. Networks must provide secure, predictable, measurable, and, sometimes, guaranteed services. Network administrators and architects can better achieve this performance from network by managing delay, delay variation (Jitter), bandwidth provisioning, and packet loss parameters with quality of service (QoS) techniques. As the concept of converged network is being widely used today where all types of traffic are required to be sent and transmitted on the same wide area network (WAN) link. Hence different applications need to be differentiated and treated according to their sensitivity to business. QoS is the suitable answer and method to solve this issue and make sure that each traffic type will be treated differently using various mechanisms of QoS. In this research different types of traffic that represent different applications are generated in WAN and local area network (LAN) where various techniques of QoS are implemented. Network performance is indicated by capturing different parameters on real time such as, delay, jitter, packet loss, and bandwidth. Based on results obtained, a set of recommendations is concluded for each QoS mechanism highlighting the suitable traffic type for this technique to be used for along with appropriate network locations for this technique to be implemented.
نسرين عادل بن لطيف (2011)