The nonlinear refractive index and the nonlinear absorption coefficient of unmodified and functional poly(methyl methacrylate) PMMA films were studied before and after the addition of the filler by the z-scan technique, using a Q-switched Nd:YAG laser at two wavelengths: 532 nm and 1064 nm, and at three input energies (13, 33 and 53) mJ. Both linear and nonlinear refractive indices and absorption coefficients of polymer films were studied by using UV-VIS spectrophotometer. The results show that the creation of functional PMMA from unmodified PMMA will increase the nonlinear optical properties in the functional PMMA/copper matrix more than in the unmodified PMMA/copper matrix. Hence, the functional PMMA appears promising as a useful third-order nonlinear material. The nonlinear refractive index is directly proportional to the input intensity and directly proportional to the increase in the concentration of the filler, while the nonlinear absorption coefficient is inversely proportional to the input energy and inversely proportional to the increase in the concentration of the filler. The nonlinear effect is more enhanced at the 532 nm wavelength than at 1064 nm..
بعد مرور عام واكثر على ظهور فيروس كورونا والعالم يواجه تسونامي تلك الجائحة التي تكاد تعصف بالوجود البشري برمته لذا اخذت البشرية على عاتقها مواصلة الجهود والابحاث للوصول الى علاج طبي يتم من خلاله مواجهة هذا الفيروس او التقليل من آثاره التي تهدد الحياة البشرية بالموت المباشر دون الاصابة، مما نتج عن تلك الجهود مجموعة من اللقاحات التي تبنتها الشركات العالمية المسؤولة الا ان الضرورة القصوى التي نتجت عنها تلك الل
... Show MoreThe cuneiform images need many processes in order to know their contents
and by using image enhancement to clarify the objects (symbols) founded in the
image. The Vector used for classifying the symbol called symbol structural vector
(SSV) it which is build from the information wedges in the symbol.
The experimental tests show insome numbersand various relevancy including
various drawings in online method. The results are high accuracy in this research,
and methods and algorithms programmed using a visual basic 6.0. In this research
more than one method was applied to extract information from the digital images
of cuneiform tablets, in order to identify most of signs of Sumerian cuneiform.
يدرس هذا البحث مشكلة اعتماد الجمهور العراقي على الصحف، باعتبارها إحدى وسائل الإعلام التقليدية، في تكوين معلوماته ومعرفته العامة. وهي دراسة وصفية اعتمدت المنهج الوصفي المسحي الذي يصور الظروف أو الاتجاهات الحالية للظاهرة قيد الدراسة ويحاول تفسيرها. استخدم الباحث الاستبانة في المقام الأول كأداة بحث، حيث تم تصميمها وتوزيعها على عينة مكونة من 150 باحثا قصديا من قراء وقراء الصحف. وينتهي الباحث بالنتائج التالية: إ
... Show Moreيتناول البحث الحماية المدنية للمستهلك في المرحلة السابقة على التعاقد الالكتروني
Abstract
One of the major components in an automobile engine is the throttle valve part. It is used to keep up with emissions and fuel efficiency low. Design a control system to the throttle valve is newly common requirement trend in automotive technology. The non-smoothness nonlinearity in throttle valve model are due to the friction model and the nonlinear spring, the uncertainty in system parameters and non-satisfying the matching condition are the main obstacles when designing a throttle plate controller.
In this work, the theory of the Integral Sliding Mode Control (ISMC) is utilized to design a robust controller for the Electronic Throttle Valve (ETV) system. From the first in
... Show Moreيأخذ هذا النوع من الدراسات اهميته في مجال الكتابة التاريخية لما لها من اهمية في بناء التراث الفكري الحضاري للامة العربية الاسلامية.
Chaotic systems have been proved to be useful and effective for cryptography. Through this work, a new Feistel cipher depend upon chaos systems and Feistel network structure with dynamic secret key size according to the message size have been proposed. Compared with the classical traditional ciphers like Feistel-based structure ciphers, Data Encryption Standards (DES), is the common example of Feistel-based ciphers, the process of confusion and diffusion, will contains the dynamical permutation choice boxes, dynamical substitution choice boxes, which will be generated once and hence, considered static,
While using chaotic maps, in the suggested system, called
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(4)
In the spreading of the Internet, mobile smart devices, and interactive websites such as YouTube, the educational video becomes more widespread and deliberative among users. The reasons for its spread are the prevalence of technologies, cheap cost, and easy to use. However, these products often lack to the distinction in video production. By following videos of an educational channel on YouTube, some comments found to discuss the lack of the content presented to motivate the learners, which lead to reduce the viewers of the videos. Therefore, there is an important decision to find general standards for the design and production of educational videos. A list of standards has been drawn up to help those interested in producing educational
... Show MoreThe theme of the Abbasid Caliph and their children great interest in the knowledge and effective not only in the history of civilization but in the history of the humanity and the sublime values. Their interest and care for the scholar ulamaa and rendering help and encouragement by their caliphs were keen for science and knowledge because whatever the scholars have a status they cannot give help without and knowledge and the practice of their role in the interest and the care
يعد الصراعات الدولية ظاهرةقديمة قدم البشرية وعلى المستوى الدولي وغالبا ما تكون الدول الصغرى هي الساحة لتصفية الصرااعت بين الدول الكبرى كما هو الحال في سوريا مما يؤدي لعدوم وجود امن انساني فيها