Enhancing Synchrony in Chaotic Oscillators by Dynamic Relaying

In a chain of mutually coupled oscillators, the coupling threshold for synchronization between the outermost identical oscillators decreases when a type of impurity (in terms of parameter mismatch) is introduced in the inner oscillator(s). The outer oscillators interact indirectly via dynamic relaying, mediated by the inner oscillator(s). We confirm this enhancing of critical coupling in the chaotic regimes of R\"ossler system in absence of coupling delay and in Mackey-Glass system with delay coupling. The enhancing effect is experimentally verified in electronic circuit of R\"ossler oscillators.Comment: 4 pages, 9 figure

Examination of the Mechanical, Corrosion, and Tribological Behavior of Friction Stir Welded Aluminum Alloy AA8011

Aluminum alloy AA8011 is emerging as a promising material for modern engineering applications in which improved tensile strength, hardness, corrosion-resistance, and wear-resistance of materials are required. Typically, AA8011 alloys are utilized in air-conditioning ducts and heat exchanger fins in ships, leisure boats, luxury vessels, workboats, fishing vessels, and patrol boats. However, the conventional welding of AA8011 is a challenging procedure. In this context, this paper focuses on the development of an effective solid-state welding methodology for AA8011 alloy welding. The AA8011 alloy was friction stir welded by varying the tool rotation speed, traverse speed, and shoulder diameter. The microhardness, tensile strength, joint efficiency, elongation, corrosion rate, and wear rate of the friction stir welded specimens were compared with the base material. Fractography analysis was conducted after the tensile test and surface morphology analysis after corrosion and wear tests, using scanning electron microscopy. The compositional elements in the corroded and worn section of the specimens were analyzed using energy-dispersive X-ray spectroscopy. Based on the joint efficiency as a primary constraint, the optimum process parameters for friction stir welding of aluminum alloy AA8011 have been established as follows: tool rotation speed of 1200 rpm, tool traverse speed of 45 mm/min, and tool shoulder diameter of 21 mm

Synthesis of g-carbon nitride-Ag3PO4 nanohybrid using Okra plant extract and their photocatalytic activity for the degradation of fluorescein and crystal violet dyes

Development of eco-friendly efficient photo catalyst is an urgent need for waste water treatment in industry. A facile eco-friendly method is established to synthesize hybrid nanocomposite of g-C3N4/Ag3PO4 using Abelmoschus esculentus plant extract and used as highly efficient photo catalyst for degradation of textile toxins and pharmaceutical waste from industrial waste water. The synthesized catalysts have been characterized by FTIR, XRD, SEM, TEM and EDAX analysis. XRD peaks confirm the cubic phase of Ag3PO4, high crystallinity and purity of nanocomposite. SEM studies show nanocomposites with rough surface and irregular morphology. TEM reports confirm the spherical morphology of silver phosphate and it is evenly wrapped on the surface of graphene sheets. EDAX confirms the purity and presence of all elements in composite. Photo catalytic activity of catalyst has been investigated towards degradation of CV and Fluorescein dyes. The superior photo catalytic performance of g-C3N4/Ag3PO4 nanohybrid composite on CV and Fluorescein dye has been observed and compared with recent report of literature. The photo catalytic studies revealed that the synthesized catalyst is efficient and degrade 95% of Fluorescein and CV within 2 hours. Reusability of the catalyst has been evaluated and it reveals stability and recyclability of the catalyst. The mechanism of photo catalytic activity has also been discussed in detail

Synthesis of g-carbon nitride-Ag3PO4 nanohybrid using Okra plant extract and their photocatalytic activity for the degradation of fluorescein and crystal violet dyes

595-603Development of eco-friendly efficient photo catalyst is an urgent need for waste water treatment in industry. A facile eco-friendly method is established to synthesize hybrid nanocomposite of g-C3N4/Ag3PO4 using Abelmoschus esculentus plant extract and used as highly efficient photo catalyst for degradation of textile toxins and pharmaceutical waste from industrial waste water. The synthesized catalysts have been characterized by FTIR, XRD, SEM, TEM and EDAX analysis. XRD peaks confirm the cubic phase of Ag3PO4, high crystallinity and purity of nanocomposite. SEM studies show nanocomposites with rough surface and irregular morphology. TEM reports confirm the spherical morphology of silver phosphate and it is evenly wrapped on the surface of graphene sheets. EDAX confirms the purity and presence of all elements in composite. Photo catalytic activity of catalyst has been investigated towards degradation of CV and Fluorescein dyes. The superior photo catalytic performance of g-C3N4/Ag3PO4 nanohybrid composite on CV and Fluorescein dye has been observed and compared with recent report of literature. The photo catalytic studies revealed that the synthesized catalyst is efficient and degrade 95% of Fluorescein and CV within 2 hours. Reusability of the catalyst has been evaluated and it reveals stability and recyclability of the catalyst. The mechanism of photo catalytic activity has also been discussed in detail

Corrosion and Tribological Characteristics of FSPed Aluminum Alloy AA5052

Friction stir processing (FSP) is a solid-state and effective process for surface modification of aluminium alloys. In this study the AA5052 alloy, widely used in marine applications, has been subjected to FSP. The FSP trials have been carried out by altering the FSP process parameters (tool rotation speed, tool traverse speed, and shoulder diameter). The friction stir processed specimens have been characterised / tested for microstructure, microhardness, sliding wear, immersion corrosion, and electrochemical corrosion. The hybrid polynomial – radial basis function-based models have been developed to determine the relationship between the process parameters and the evaluated properties. Furthermore, the optimum parameters for obtaining high hardness, wear resistance, and corrosion resistance have been determined. Microstructure evaluation in the friction stir processed specimens has shown refinement and uniform dispersion of β particles throughout the α-Al matrix. The results show that the improvement in properties is a result of the homogeneous dispersion of secondary β phase particles in the matrix. Friction stir processing of AA5052 alloy has improved hardness by ~14.5%, wear resistance by ~83%, and corrosion resistance ~87%. The optimum process window for friction stir processing of AA5052 alloy is tool rotation speed between 500 rpm and 900 rpm, tool traverse speed between 10 mm/min and 30 mm/min, and tool shoulder diameter of 18 mm and 21 mm

Isolated/non-isolated quad-inverter configuration for multilevel symmetrical/asymmetrical dual six-phase star-winding converter

This article presents the developments of a novel isolated/non-isolated quad inverter configuration for multilevel dual six-phase (twelve-phase) star-winding converter. The modular circuit consists of four standard voltage source inverters (VSIs). Each VSI is incorporated with one bi-directional switch (MOSFET/IGBT) per phase and links with the neutral line through two capacitors which allows symmetrical and asymmetrical operations. A modified single carrier five-level modulation (MSCFM) algorithm is developed and modulates each 2-level VSI as a 5-level output multilevel inverter. The entire AC converter is numerically modeled using Matlab/PLECS simulation software and the predicted behavior of the system is analyzed and presented. Good agreement is obtained between these results and the theoretical analysis. Suitable applications for the converter include (low-voltage/high-current) medium power systems, electrical vehicles, AC tractions, and ‘More-Electric Aircraft’ propulsion systems

Adsorption modelling studies for the removal of Rose Bengal dye from aqueous solutions using a natural adsorbent perlite

604-611Modelling studies for the adsorptive eradication of a dye Rose Bengal dye in aqueous solutions using an adsorbent perlite have been exploited. A batch mode adsorption technique was performed to find the influence of contact time, strength of the Rose bengal dye, dosage of the perlite, pH and temperature. The equilibrium of the adsorption has been achieved only after the contact time of 40 min. The kinetic behaviour of the adsorption has been evaluated using the pseudo first-order as well as the second-order types. The achieved kinetic equation statistics of pseudo second-order kinetic equation has a close proximity with unity. Equilibrium adsorption values are obtained from the Freundlich and Langmuir isotherm. From the correlation data, Freundlich isotherm remains suited to describe the adsorption behaviour of Rose bengal dye on the perlite. From the experimental data, the thermodynamic parameters like ∆Ho, ∆So, and ∆Go are assessed. The calculated result was shown that the adsorption behaviour is exothermic as well as immediate in description. The dimensionless separation factor has been shown that perlite is the substitute to other adsorbents for the elimination of rose Bengal dye from the aqueous solution