The main objectives of this thesis is oriented toward three directions: The first objective is to study fuzzy set theory with some basic properties related to the theory of variational problems.The second objective is to study variational problems with fuzzy functions, fuzzy condition and fuzzy boundaries by using different approaches for defuzzification, such as centroid method, α-cut method, centroid point and
In this thesis, we study the gamma distribution because it has many applications in life – testing, survival and reliability investigation that appear in medical studies of chronic diseases and industrial life – testing. Approximation to the mean and variance of moments method estimators is made theoretically by using Taylor series expansion approximated up to second partial derivatives. The maximum likelihood estimators are derived and compared with several estimators that proposed in the literature.
The main objective of this thesis is to study and solve the Volterra integral and integro-differential equation and some scientific models for real life problems. This objective may be divided into three sub objectives, as follows:
