فهرست مطالب ouada

The combination of neural networks and fuzzy controllers is considered as the most efficient approach for different functions approximation, and indicates their ability to control nonlinear dynamical systems. This paper presents a hybrid control strategy called Neuro-Fuzzy Sliding Mode Control (NFSMC) based on the Brushless Doubly fed Induction Generator (BDFIG). This replaces the sliding surface of the control to exclude chattering phenomenon caused by the discontinuous control action. This technique offers attractive features, such as robustness to parameter variations. Simulations results of 2.5 KW BDFIG have been presented to validate the effectiveness and robustness of the proposed approach in the presence of uncertainties with respect to vector control (VC) and sliding mode control (SMC). We compare the static and dynamic characteristics of the three control techniques under the same operating conditions and in the same simulation configuration. The proposed controller schemes (NFSMC) are effective in reducing the ripple of active and reactive powers, effectively suppress sliding-mode chattering and the effects of parametric uncertainties not affecting system performance.

The present study investigated the existing relationship between computer assisted semen motility parameters and gametes motility duration, known to express semen quality and fertilizing capacity in fish. The objective was particularly to identify computer aided semen analysis (CASA) parameters that could be used as potential fertility predictors. Semen samples were collected from the beginning to the end of the spawning season of Barbus barbus callensis, a freshwater fish abundantly distributed throughout North Africa. Semen was simultaneously analyzed using optical microscopy including semen motility duration (SMD) measurement, by the aid of a computer-assisted semen analyzer. The measured CASA parameters were: straight line velocity (VSL), average path velocity (VAP), curvilinear velocity (VCL), beat cross frequency (BCF), amplitude of lateral head displacement (ALH), linearity and straightness. The results showed that motility duration evolved in a similar manner as several CASA parameters. Significant correlation coefficients expressed these relationships with r = 0.74, 0.32, 0.16 and 0.45 for VSL, VAP, VCL and BCF, respectively. No correlations were observed when studying relationships between motility duration, STR, LIN and ALH, with r = 0.08, 0.06 and 0.006, respectively. The present results showed that CASA motility parameters are strongly related to motility duration. VSL was revealed as the main parameter being highly correlated to motility duration (r = 0.74). This quantitatively and objectively measured parameter is revealed to be a useful indicator of semen quality and could serve as a potential indicator of fertility outputs in fish.