Scielo RSS <![CDATA[Journal of applied research and technology]]> vol. 14 num. 6 lang. es <![CDATA[SciELO Logo]]> <![CDATA[Diffusion behavior study of model diesel components in polymer membranes based on neural network for pattern recognition]]> Abstract: A neural network for a pattern recognition model is developed for the first time to predict the diffusion behavior of the model diesel components (dibenzothiophene and quinolone) in three different membranes of polyvinyl alcohol, polyvinyl chloride and polymethyl acrylate. The simulation results show that the excellent performance target parameter optimization area can be obtained and the effective desulfurization and denitrification agent can be found. Compared with the advanced molecular dynamic simulation method and verified by adsorption experiments, the simulation values are in good agreement with the experimental data and molecular dynamic simulation data. The results reveal that the polyvinyl chloride membrane can improve the diffusion selectivity of dibenzothiophene and it is selected as the most effective desulfurization agent, while the polyvinyl alcohol membrane is selected as the most effective denitrification agent to remove the nitrogen compounds. Development time and effort of screening desulfurization agent and denitrification agent tests are also reduced because the neural network for the pattern recognition model provides ready-made decisions. Therefore, the neural network for pattern recognition is a prospect and practicable theoretical method to research the diffusion behavior of model diesel components in polymer membranes. <![CDATA[Three dimensional (3D) percolation network structure: Key to form stable carbon nano grease]]> Abstract: Nano grease is found to be stable and homogeneous (wherein carbon nanotubes act as sole thickeners and oil is polyalphaolefin (PAO)). This is a good indication that three dimensional (3D) percolation network structures among carbon nanotubes (single wall and multi wall) play a crucial role in stabilization. To better understand this assumption and provide further evidence, some additional carbon nanomaterials, such as carbon nanofiber (CNF), graphene, fullerene (C60), Ni-coated single wall carbon nanotube (SWNT), are selected to make the grease. Unfortunately, CNF, graphene, fullerene (C60) and Ni-coated SWNT do not form stable greases as nanotubes do. In addition, SWNTs were mixed with CNF and Ni-coated SWNT respectively to see if stable grease could be formed. The results indicate that the CNF/SWNT did not form the stable grease, while Ni-coated SWNT/SWNT did. Inter molecular Van der Waals forces could reasonably explain these experimental results. Appropriate tube size (nanotube and nanofiber), stereo structure (nanotube, graphene and fullerene), surface energy (nanotube and Ni-coated nanotube) are critical factors that determine if Van der Waals forces could take effect or not. The scientific merit of this paper is that we understand in what manner stable greases are formed and what kinds of carbon materials are appropriate for acting as sole thickener. <![CDATA[A gradient descent control for output tracking of a class of non-minimum phase nonlinear systems]]> Abstract: In this paper we present a new approach to design the input control to track the output of a non-minimum phase nonlinear system. Therefore, a cascade control scheme that combines input-output feedback linearization and gradient descent control method is proposed. Therein, input-output feedback linearization forms the inner loop that compensates the nonlinearities in the input-output behavior, and gradient descent control forms the outer loop that is used to stabilize the internal dynamics. Exponential stability of the cascade-control scheme is provided using singular perturbation theory. Finally, numerical simulation results are presented to illustrate the effectiveness of the proposed cascade control scheme. <![CDATA[Design, construction and control of a SCARA manipulator with 6 degrees of freedom]]> Abstract: The design and implementation of a robot manipulator with 6 degrees of freedom (DOF), which constitutes a physical platform on which a variety of control techniques can be tested and studied, are presented. The robot has mechanical, electronic and control systems, and the intuitive graphic interface designed and implemented for it allows the user to easily command this robot and to generate trajectories for it. Materializing this work required the integration of knowledge in electronics, microcontroller programming, MatLab/Simulink programming, control systems, communication between PCs and microcontrollers, mechanics, assembly, etc. <![CDATA[Investigation and correction of error in impedance tube using intelligent techniques]]> Abstract: Errors arise in the measurement of sound absorption coefficient using impedance tube due to various factors. Minimizing the errors require additional hardware or proper calibration of certain components. This paper proposes a new intelligent error correction mechanism using mathematical modelling and soft computing paradigms. A low cost impedance tube is designed, developed and its performance is compared with a commercially available standard tube. A particle swarm optimization and neural network based system is developed to reduce the random and systematic errors in the developed impedance tube. The proposed system is tested using various porous and non-porous functional textile materials and the results are validated. A significant reduction in error is obtained at all frequency ranges with PSO based prediction method. <![CDATA[Kinetic studies of surface modification of lignocellulosic Delonix regia pods as sorbent for crude oil spill in water]]> Abstract: Acetylation method was used in the modification of Delonix regia pods (DRPs) as sorbent for crude oil cleanup in water. Fourier transform infra-red (FTIR) and scanning electron microscope (SEM) analysis were used to investigate the influence of acetylation and crude oil sorption on the sorbent (DRPs). Reaction conditions played significant roles on the extent of acetylation of DRPs. Temperatures of 303 K and 343 K were found to be the most suitable acetylation temperatures of DRPs. Intra-particle diffusion was the rate controlling mechanism for acetylating DRPs while the contributing mechanisms depend on the temperature of acetylation. The crude oil sorption capacity (OSC) of modified DRPs was significantly higher than that of unmodified DRPs. Physical and chemical reactions were faster in the crude oil sorption by modified DRPs than the unmodified while diffusion into the pores of the modified DRPs was slower than in the unmodified. Hydrophobic functional groups were enhanced by acetylation and crude oil molecules were adsorbed at these functional groups. Surface structure, pore sizes and fiber lengths of the sorbent were affected by acetylation and crude oil sorption. FTIR and SEM showed clear evidence of successful acetylation and crude oil sorption. Analysis of variance (ANOVA) was used to determine the statistical difference of weight percent gain (WPG) obtained from the acetylation of DRPs at different reaction parameters such as temperature and time. The OSC of modified and unmodified sorbents at various contact times, were also compared using ANOVA. <![CDATA[Application of poly(aspartic acid-citric acid) copolymer compound inhibitor as an effective and environmental agent against calcium phosphate in cooling water systems]]> Abstract: Poly(aspartic acid-citric acid) copolymer (PAC) is a new product of poly(carboxylic acid) scale inhibitor. The study aims to develop a "green" water treatment agent for calcium phosphate scale. The article compares the efficiency of three polymeric antiscalants, poly(aspartic acid-citric acid) copolymer (PAC), polymaleic acid (HPMA) and a compound inhibitor (PAC-HPMA), for calcium phosphate scale prevention under varying experimental conditions. Inhibitor concentration, calcium concentration, system pH, temperature and experimental time were varied to determine their influences on inhibitor performance by the static scale inhibition method. The copolymer (PAC) was characterized by FTIR, 1H NMR and 13C NMR. The compound inhibitor was applied in the actual circulating cooling water system. An atomic force microscope (AFM), X-ray powder diffraction (XRD) and a scale formation process analysis were used to explore the scale inhibition mechanism. The results showed that scale inhibition rates of PAC, HPMA and PAC-HPMA against Ca3(PO4)2 were, respectively, about 23%, 41.5% and 63% when the dosage was 8 mg/L in the experiment. The compound inhibitor showed the better inhibition performance than the above two kinds of monomers. Under the actual working conditions, the inhibition rate of compound inhibitor was close to 100% and completely met the actual application requirements of scale inhibitor in circulating cooling water systems. The main inhibition mechanism was the decomposition-chelation dispersion effect. The compound inhibitor can be used as an efficient "green" scale inhibitor for calcium phosphate.