The proposed work is an attempt to investigate the stability of the nonlinear system by using a whale optimization algorithm as of one of the meta-heuristic optimization methods, and this investigation was conducted on a single inverted pendulum as a study model. The evaluation measures which were used in this article values of gain and sliding surface of the conventional sliding mode controller to illustrate the extent of the system`s stability. Furthermore, control action, the relationship between error and its derivative, desired, and actual position in addition to sliding response graphically showed the feasibility of the proposed solution. The attained results illustrated considerable improvement in the settling time and minimizing the impact of chattering behavior.

Most encryption techniques are deals with English language, but that deals with Arabic language are few. Therefore, many researchers interests with encryption ciphers that applied on text which wrote in Arabic language. This reason is behind this paper. In this paper, there are three cipher methods implemented together on Arabic text. Using more than one cipher method is increase the security of algorithm used. Each letter of plaintext is encrypted by a specified cipher method. Selection process of one of three cipher methods used in this work is done by controlling process that selects one cipher method to encrypt one letter of plaintext. The cipher methods that used in this paper are RSA, Playfair and Vignere. Each one of them has different basis mathematical model. This proposed encryption Arabic text method gives results better than previous related papers.