The reduction of vibration properties for composite material (woven roving E-glass fiber plies in thermosetting polyester matrix) is investigated at the prediction time under varied combined temperatures (60 to -15) using three types of boundary conditions like (CFCF, CCCF, and CFCC). The vibration properties are the amplitude, natural frequency, dynamic elastic moduli (young modulus in x, y directions and shear modulus in 1, 2 plane) and damping factor. The natural frequency of a system is a function of its elastic properties, dimensions, and mass. The woven roving glass fiber has been especially engineered for polymer reinforcement; but the unsaturated thermosetting polyester is widely used, offering a good balance of vibration properties at moderate or ambient temperatures, and also at relatively low cost. The mismatch between matrix and fiber yarns gives a predominant role for the fiber's mechanics where the matrix is the area where most damage mechanisms develop. The free vibration test was carried out for (5, 10, 15, 20, 25, 30) minutes. The composite plate was exposed to (75) of thermal gradient for ten times in various times at different stages. The results were classified into experimental and finite element using software ANSYS Ver. 9.
التعريف بالبحث
اهمية البحث والحاجة اليه :.
اللغة وظيفة اساسية الا وهي التواصل ولقد زدادت الحاجة في هذا العصر الى تعلم اللغات والاحاطة بها اكثر من اي وقت مضى يوصفها الاساس الذي يعتمد عليه في تعلم المواد الاخرى .
فاللغة اداة التفكير ونشر الثقافة في بلدان كثيرة مثل بلاد الاندلس التي اشرقت منها الحضارة في ا
... Show MoreThe research aims to know the impact of using the strategy (think-tac-toe) in the achievement of Biology subject for female students of fourth grade scientific branch. The research sample consisted of 70female students the of fourth Grade scientific Branch . The students were divide randomly, equally to two groups, experimental and control group. the two groups are equaled in the variable ( intelligence, age, previous information, former achievement of biology subject ) and the strategy applied over the entire semester. built an achievement test and it has been the expense of validity, and the reliability and The psychometric properties, and the data were analyzed statistically by recourse to Statistical package SPSS, the results showed
... Show Moreمشكلة البحث
إن طرائق تدريس المواد الشرعية ما تزال تُدّرس بطرائق لا تتناسب مع ما توصل إليه البحث العلمي في الميدان التربوي في الوقت الحاضر ، وهذا مما سبب في وجود أزمة فكرية وعلمية في الأقسام التي تدرس المناهج الدينية .
على الرغم من الأهمية الكبيرة لمادة التلاوة ، إلا أن هناك مشكلة كثيرا ما يعاني منها مدرسو هذه المادة، وهي انصراف الطلبة عن حفظ النصوص القرآن
... Show MoreThis work studied the electrical and thermal surface conductivity enhancement of polymethylmethacrylate (PMMA) clouded by double-walled carbon nanotubes (DWCNTs) and multi-walled carbon nanotube (MWCNTs) by using pulsed Nd:YAG laser. Variable input factors are considered as the laser energy (or the relevant power), pulse duration and pulse repetition rate. Results indicated that the DWCNTs increased the PMMA’s surface electrical conductivity from 10-15 S/m to 0.813×103 S/m while the MWCNTs raised it to 0.14×103 S/m. Hence, the DWCNTs achieved an increase of almost 6 times than that for the MWCNTs. Moreover, the former increased the thermal conductivity of the surface by 8 times and the later by 5 times.
The research aims to identify the effect of applying administrative decentralization to an educational performance by assessing educational performance before and after the process of transferring powers from the federal government (the Iraqi Ministry of Education) to local governments (governorates) as well as identifying the appropriate central or decentralized administrative system to advance the educational reality and performance. To achieve the goal of the research, educational data was collected and analyzed, as well as the measurement of educational performance indicators and analysis during two phases, the first represents the stage of applying the central system and spanned between the academic year (2011-2012) and the
... Show More
Tax fraud is following different methods of tax evasion (bypassing the laws, instructions and regulations related to tax) by not showing the real taxable income by using laws, instructions and regulations improperly, and because of the weak basic role of forensic accounting in detecting and reducing tax fraud, the problem has become more influential on the state general tax income. The main objective of the research is to identify forensic accounting and the extent to how it can be applied in the General Tax Authority to assist forensic authorities in issuing judgments in fraud cases. To achieve the objectives of the research, the descriptive analytical approach was used to reach the topic of the research, and a questionnaire (co
... Show MoreThis paper presents the results of experimental investigations to predict the bearing capacity of square footing on geogrid-reinforced loose sand by performing model tests. The effects of several parameters were studied in order to study the general behavior of improving the soil by using the geogrid. These parameters include the eccentricity value, depth of first layer of reinforcement, and vertical spacing of reinforcement layers. The results of the experimental work indicated that there was an optimum reinforcement embedment depth at which the bearing capacity was the highest when single-layer reinforcement was used. The increase of (z/B) (vertical spacing of reinforcement layer/width of footing) above 1.5 has no effect on the re
... Show MoreThis research is an initial attempt to explore the reality of reform and its concept in Islam, and to describe the presence of educational practices in the Arab-Islamic heritage. The importance of this research lies in addressing a number of important issues related to the contemporary Islamic reform system. The research showed the need for authentic educational reform values that draw their reference from the origins of Islam. The research also emphasized the analysis of the reality of education in the Muslim world and the identification of its problems and the search for solutions through a quick and comprehensive look at the diverse contributions of Muslim thinkers to Islamic educational reform thought, and their active role in addressin
... Show More
(10)
(4)
