Mathematics and Computer Applications - Sciene

 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:

This thesis developed three defuzzification approaches to convert the coefficients and the variables of the fuzzy linear programming problems (FLPP) into crisp (deterministic) linear programming problems (CLPP) and obtain the critical path with the optimal completion time for the different fuzzy network problems.The three defuzzification approaches are based respectively on the philosophies of probability density function, ranking measures and the program evaluation and review technique (PERT).Finally, the critical path method (CPM) has been used to compare its