Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

NSGA-II Based Multi Objective Design Optimization of Resistive Superconducting Fault Current Limiters

Superconducting fault current limiters (SFCLs) are the devices that uses the superconducting properties of the materials to limit the fault current. In comparison to the conventional fault current limiters (FCLs), the SFCL has advantage that its current limiting property is inherent and no external controls are required. However, to achieve the exact current limiting ratings with other characteristics like quench time, recovery time, peak current etc. a design optimization is required. Since the whole characteristics of SFCL depends upon the superconducting material adopted, and the parameters of cooling systems. The parameters defining the behavior of these two entities are selected as optimization variables. Because in this work second-generation high temperature superconducting (HTS) material known as YBCO (Yttrium Barium Copper Oxide ) is considered. Hence, in this paper non-dominated Sorting GA (NSGA-II) optimization algorithm is adopted that exploits the 2G YBCO mathematical model relating its electrical and thermal characteristics and cooling system specifications to find the optimal parameters according to the requirements (or objectives) of resistive-SFCL. The simulation results show that the presented algorithm is able to achieve multiple design objectives (required for SFCL) simultaneously within the range of 5%.

Model Reference Control With Command Shaping for a Micro-Electromagnetic Actuator With Input Constraints

Model Reference Control is used to force a system to track the response of an assigned reference model, where the reference model is often designed to reflect the desired properties of the system. If a linear reference model is used, Model Reference Control has a linearizing effect for nonlinear plants, allowing it to be cascaded with linear controllers. Model Reference Control has been used to force nonlinear flexible systems to behave linearly such that input shaping can be used to limit residual vibration. However, when a system encounters saturation limits, the vibration limiting property of input shaping is degraded. This paper proposes Model Reference Control with an adaptive input shaping method to account for saturation by modifying the input shaper after saturation has been encountered. Simulations are presented to illustrate the effectiveness of this method in canceling residual vibration for a nonlinear electromagnetic actuator subject to input constraints.