Robust Model Reference Adaptive Intelligent Control

In this paper a Neural Network based Model Reference Adaptive Control scheme (NNMRAC) is proposed. In this scheme, the controller is designed by using parallel combination of the conventional Model Reference Adaptive Control (MRAC) scheme and Neural Network (NN) controller. In the conventional MRAC scheme, the controller is designed to realize plant output converging to reference model output based on the plant which is linear. This scheme is used to control linear plant effectively with unknown parameters. However, it is difficult for a nonlinear system to control the plant output in real time applications. In order to overcome the above limitations, the NN-MRAC scheme is proposed to improve the system performances. The control input of the plant is given by the sum of the MRAC output and NN controller output. The NN controller is used to compensate the nonlinearities and disturbances of the plant that are not taken into consideration in the conventional MRAC. The simulation results clearly show that the proposed NN-MRAC scheme have better steady state and transient performances than those of the current adaptive control schemes. Thus, the proposed NN-MRAC scheme named as Robust Model Reference Adaptive Intelligent Control (RMRAIC) is found to be extremely effective, efficient and useful in the field of control system.     

Study of a nonuniform heat source over a Riga plate using nth-order chemical reaction on Oldroyd-B nanofluid flow for two-dimensional motion

A variety of fluid models are proposed, due to the uncertain flow diversity and rheological features of non-Newtonian fluids, out of which, viscoelastic Oldroyd-B nanofluid is considered here with a nonuniform heat source over a Riga plate using an nth-order chemical reaction. The ever increasing demand for chemical reactions in hydrometallurgical, chemical, and biomedical industries necessitates studying the behavior of heat and mass transfer in the presence of chemical reaction; a few of its applications are manufacturing of glassware or ceramics, food processing, polymer production, particulate water inflows, dehydration and drying operations in the chemical industry, and numerous applications in agricultural fields and many branches of engineering and sciences. To solve the set of nonlinear DEs, which are found after applying a suitable transformation on the governing nonlinear PDEs, a robust numerical technique, such as the fourth-order Runge–Kutta method, is employed in the current motion problem. Also, the influences of all substantial thermophysical parameters are discussed graphically and analytically. Furthermore, the major outcomes of the results are: attenuation in the relaxation time leads to a rise in the fluid momentum significantly near the wall and the solutal profile retards with an enhanced Brownian motion that results in the retardation in the bounding surface thickness of the profile.     

Studies in Effect of Synthetic and Natural Microfibers on Properties of High-Density Polyethylene-Reinforced Composite

Natural fibers are now arising as one of the promising reinforcement components for fiber-reinforced polymer composites. A study has been conducted to optimize weight concentration of surface-treated and surface-untreated microfibers on the properties of high-density polyethylene composite. Polyethylene terephthalate and henequen microfibers in varying compositions, namely, 1, 3, 5, 8, 10, and 20?wt% were reinforced into high-density polyethylene matrix. These fibers were treated with coupling agent at 0.5?wt%. Vinyltrimethoxysilane-treated composite shows enhanced properties as compared to untreated microfiber composite. Rheological and morphological results reveal that addition of coupling agent improves dispersion and matrix fiber interactions.     

A technique to match highly similar 3D objects with an application to biomedical security

Multimedia Tools and Applications - Biometric technologies such as the face, fingerprint, and iris recognition have important utility in biomedical and healthcare applications. The use of...     

Mechanistic insights into efficient reversible hydrogen storage in ferrotitanium

Although FeTi is a well-known hydrogen storage material, producing FeTi on a commercial scale is quite challenging, and generally, one ends up with a multi-phase system consisting of Fe₂Ti and FeTi. As Fe₂Ti is inert towards hydrogen, it lowers the hydrogen storage efficacy of FeTi. However, there are some reports, which propose that the presence Fe₂Ti in FeTi, primarily on the surface is inevitable and it helps in activation of FeTi. Here, we report results of targeted experiments together with first-principles density functional theory (DFT) based calculations to investigate the hydrogen storage properties of FeTi vis-à-vis origin of inertness of Fe₂Ti towards hydrogen storage. The formation enthalpies, calculated using density functional theory, of FeTi–H system were found to be very close to the experimental values (?28.1 and ?33.72 kJ/mol H₂ for FeTiH and FeTiH₂ respectively), and that of Fe₂Ti–H systems was positive, indicating the inability to form stable intermetallic-hydrides. This corroborates well with the experimental observations, that the pure phase of Fe₂Ti cannot store hydrogen. Further, the Gibbs free energy for FeTiH and FeTiH₂ were evaluated at 298 K using first-principles quantum mechanics and statistical thermodynamics theories. The vibrational and electronic entropies were calculated using Debye theory of heat capacities. Gibbs free energy at 298 K for FeTiH and FeTiH₂ were found to be ?5.01 and ?3.52 kJ/mol of H₂, respectively. Our present study concludes that proper care must be taken to avoid or minimize the formation of Fe₂Ti during the production of FeTi.     

Reduced band gap & charge recombination rate in Se doped α-Bi2O3 leads to enhanced photoelectrochemical and photocatalytic performance: Theoretical & experimental insight

For better utilization of solar spectrum and complete redox of water for water splitting applications, it is required to have a semiconductor which is photoactive in visible region. In this study, we report theoretical and experimental investigations on morphological and opto-electronic modifications induced in α-Bi₂O₃ due to Selenium (Se) doping tested for photoelectrochemical (PEC) & photocatalytic properties. Density Functional Theory (DFT) calculations revealed band gap reduction and direct to indirect transitions in Se-doped α-Bi₂O_3. This reduction in band gap is attributed to hybridization of Se p & Bi s in valence band and Se d & Bi p orbital in conduction band. To support this finding experimentally, we synthesized Se-doped α-Bi₂O₃ using simple chemical precipitation method and measured its band gap using photoluminescence and UV–Vis spectroscopy. Experimental results also confirmed the reduction in band gap energy and recombination rate of charge carriers as compared to pristine α-Bi₂O₃ sample. PEC study of Se-doped α-Bi₂O₃ showed an increased photocurrent density, charge carrier density and lowered impedance, which indicates its efficient solar spectrum utilization and better hydrogen generation efficiency. Photocatalytic measurement also revealed higher rate of dye degradation with Se doped α-Bi₂O₃.