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In this research the mathematical model of surface electric currents induced on axisymmetric conductive body of revolution has been formulated and solved numerically by implementing the (MoM) method. Computer simulation was developed to solve the model numerically .The resulted radiation pattern was sketched Reduction of sidelobe and beamwidth thickness was achieved by increasing the number of a apertures and changing their corresponding interspaces.

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In this paper, the electromagnetic (EM) scattering fromconductingbodies of revolution coated by dielectric layer was calculated by using moment of method with Galerkin's approach, and applying the equivalence principle to determine the electric and magnetic currents on the surface.The mathematical analysis and the programs were checked to know the validity of the formulation by comparing our results with the published results. The computed results revealed the significant effect of the coated layer on the Radar cross section reduction with respect to the conducting body. Finally, this formulation was applied to study a proposed rocket which is more complex body than the previous shape, and calculate its radar cross section, and study of the effect of the dielectric constant and the thickness of the dielectric layer on the RCS.

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In this study, different methods were used for estimating location parameter and scale parameter for extreme value distribution, such as maximum likelihood estimation (MLE) , method of moment estimation (ME),and approximation estimators based on percentiles which is called white method in estimation, as the extreme value distribution is one of exponential distributions. Least squares estimation (OLS) was used, weighted least squares estimation (WLS), ridge regression estimation (Rig), and adjusted ridge regression estimation (ARig) were used. Two parameters for expected value to the percentile as estimation for distribution function were used .Several models from extreme value distribution were used for data generating , for different sample sizes (small, medium, and large).The results were obtained by using simulation technique, Programs written using MATLAB program were used. To compare the performance for the methods used in this study, the mean squared error criterion (MSE) and mean absolute squared error criterion (MAPE) for two parameters for the extreme value distribution were used as criterion to compare the performance for the methods . The results showing according to the two criterions (MSE &MAPE), that maximum likelihood estimation is the best of all of the others methods, following by the method of moment estimation . The adjusted ridge regression estimation method have best performance for the suggested parameter for expected value to the percentile which was used as estimation for distribution function.

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In this study, different methods were used for estimating shape parameter and scale parameter for Lomax distribution, which include method of moment estimation (MOM), and method of L-moment estimation (L-MOM) and method of probability weighted moments (PWM) for type- 1 and type- 2 (proposed) for unbiased and biased estimators. Several models used from the Lomax distribution for data generating, for different sample sizes (small, medium, and large). The results were obtained by using simulation technique; programs written by using MATLAB program were used. To compare the performance for the methods used in this study, the mean squared error criterion (MSE) and total derivation (TD) for two parameters for the Lomax distribution were used as criterion to compare the performance for the methods. The results showing according to the most of the criterions ,that methods of probability weighted moments (PWM) for type -1 (proposed) for unbiased and biased estimators have the same result which obtained by another methods were used in this study.

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في هذا البحث استخدمت طرائق العزوم لاشتقاق مقدرات معلمتي الشكل والقياس لتوزيع دالة القوى, التي تضمنه طريقة العزوم (MOM) والعزوم –L (L-MOM) والعزوم الاحتمالية الموزونة من النوع الأول (IPWM1) المتحيزة (U-IPWM1) وغير المتحيزة (B-IPWM1) والعزوم الاحتمالية الموزونة من النوع الثاني المقترح استخدامها (IPWM2(proposed.)) المتحيزة (U-IPWM2(proposed)) وغير المتحيزة (B-IPWM2(proposed)).تم استعمل عدة نماذج من توزيع دالة القوى لتوليد البيانات , لإحجام عينات مختلفة (الصغيرة والمتوسطة والكبيرة). استحصلت النتائج باستخدام أسلوب المحاكاة ببرامج مكتوبة ببرنامج Matlab. لمقارنة أداء الطرائق المستخدمة في هذا البحث, فقد اعتمد معيار متوسط مربع الخطأ (MSE) ومعيار الانحراف الكلي (TD) لمقدرات معلمتي توزيع دالة القوى كمعيار لمقارنة الأداء للطرائق المستخدمة. تبين نتائج البحث وفقا للمعيارين بان طريقة التقدير المقترحة للعزوم الاحتمالية الموزونة من النوع الثاني الافضل بين طرائق التقديرالمستخدمه , فعلى الرغم من إن طريقتي العزوم الاحتمالية الموزونة من النوع الأول والثاني أعطت نتائج متشابهة لتقدير معلمتي التوزيع ومعيار متوسط مربع الخطأ (MSE) ,إلا إن طريقة التقدير المقترحة للعزوم الاحتمالية الموزونة من النوع الثاني أعطت اقل قيمة لمعيار الانحراف الكلي (TD) مقارنة بكل طرائق التقدير المستخدمة في البحث, لكل العينات والحالات .

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