in this research the chaocity of precipitation time series in daily, weekly and monthly scales in the pole-kohneh and ghourbaghestan stations located in qarah-soo watershed is investigated. in order to reassure about the absence of stochastic behavior of the time series, method of surrogate data is applied. thereafter, the aperiodicity of the time series is investigated using power spectrum ana...

We investigate the hard nonresonant excitation of the forced Duffing equation with a positive damping parameter E. Using the symbolic manipulation system MACSYMA, a computer algebra system. we derive the two term perturbation expansion by the method of multiple time scales. The resulting approximate solution is valid for small values of the coefficient e As the damping parameter e increases, th...

The accuracy of the National Research Council 2.1 m cesium beam frequency standard has been re-evaluated using the two NRC hydrogen masers as stable comparison standards. At the time of re-evaluation, the various uncertainties gave rise to an error limit of :!:3.8 x 10-12, with a most probable value of :!:1.5 x 10-12 if they were assumed to be random. Mter application of all corrections, the ag...

In this paper, we study the concept of generalized differentiability for fuzzy-valued functions on time scales. Usingthe derivative of the product of two functions, we provide solutions to first order linear fuzzy dynamic equations. Wepresent some examples to illustrate our results.

‎In this paper‎, ‎we develop the theory of hybrid differential‎ ‎equations on time scales‎. ‎An existence theorem for hybrid‎ ‎differential equations on time scales is given under Lipschitz ‎conditions‎. ‎Some fundamental fractional differential inequalities‎ ‎are also established which are utilized to prove the existence of‎ ‎extremal solutions‎. ‎Necessary tools are considered and the‎ ‎compa...