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CdS microspheres composed of nanocrystals and their photocatalytic activity.
Rengaraj, Selvaraj,Jee, Sun Hee,Venkataraj, Selvaraj,Kim, Younghun,Vijayalakshmi, Selvaraj,Repo, Eveliina,Koistinen, Arto,Sillanp??, Mika American Scientific Publishers 2011 Journal of Nanoscience and Nanotechnology Vol.11 No.3
<P>A simple and template-free solution phase synthesis method has been developed for the preparation of novel CdS hollow microspheres using cadmium nitrate and thioacetamide precursors. In this manuscript, we demonstrate that process parameters such as the reaction time, precursor ratio, and reaction temperature strongly influence the morphology of the final product. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction (XRD), Raman spectroscopy, high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray diffraction (EDX) analysis, X-ray photoelectron spectroscopy (XPS), and UV-visible diffused reflectance spectroscopy (UV-DRS). XRD analysis confirmed the cubic structure of the CdS microspheres, which has also been further supported by Raman spectroscopy. The HR-SEM measurements revealed the spherical morphology of the CdS microspheres which has been evolved by the oriented aggregation of the primary CdS nanocrystals. The TEM measurements confirmed the hollow shell-like structure of the spheres; the formation of their hollow interiors can be explained by the Ostwald ripening mechanism. UV-DRS studies showed that the band gap of the CdS microspheres increased with increasing cadmium-nitrate-to-thioacetamide ratio. Furthermore, studies of photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading methyl tert-butyl ether (MTBE) in aqueous solution under visible-light illumination. These results suggest that CdS microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation.</P>
Embargo Nature of CuO-PANI Composite Against Corrosion of Mild Steel in Low pH Medium
Selvaraj, P. Kamatchi,Sivakumar, S.,Selvaraj, S. The Korean Electrochemical Society 2019 Journal of electrochemical science and technology Vol.10 No.2
Incorporation of CuO nanoparticles during the polymerization of aniline in the presence of ammonium peroxydisulphate as an oxidizing agent and sodium salt of dodecylbenzene sulphonic acid as dopant as well as surfactant yielded water soluble CuO-PANI composite. Comparison of recorded spectra like FTIR, XRD and SEM with reported one confirm the formation of the composite. Analysis by gravimetric method exposes that the synthesized composite is having resistivity against corrosion, with slight variation in efficiency on extending the time duration up to eight hours in strong acidic condition. OCP measurement, potentiodynamic polarization and EIS studies also confirms the suppression ability of composite against corrosion. Riskless working environment could be provided by the synthesized composite during industrial cleaning process.
Selvaraj, D. Edison,Mohanadasse, K.,Sugumaran, C. Pugazhendhi,Vijayaraj, R. The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.5
Nano composite materials were multi-constituent combinations of nano dimensional phases with distinct differences in structure, chemistry and properties. Nano particles were less likely to create large stress concentrations and thereby can avoid the compromise of the material ductility while improve other mechanical properties. Corona discharge was an electrical discharge. The ionization of a fluid surrounding a conductor was electrically energized. This discharge would occur when the strength of the electric field around the conductor was high enough to form a conductive region, but not high enough to cause electrical breakdown or arcing to nearby objects. This paper shows all the studies done on the preparation of nano fillers. Special attention has given to the ACSR transmission line conductor, TiO<sub>2</sub> nano fillers and also to the evaluation of corona resistance on dielectric materials discussed in detail. The measurement of the dielectric properties of the nano fillers and the parameters influencing them were also discussed in the paper. Corona discharge test reveals that in 0%N ACSR sample corona loss was directly proportional to the applied line voltage. No significant change in corona loss between 0%N and 1%N. When TiO<sub>2</sub> nano filler concentration was increased up to 10%N fine decrement in corona loss was found when compared to base ACSR conductor, corona loss was decreased by 40.67% in 10%N ACSR sample. It was also found from the surface conditions test that inorganic TiO<sub>2</sub> nano filler increases the key parameters like tensile strength and erosion depth.
Selvaraj, Seenivasan,Moon, Hee,Kim, Do-Heyoung Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.429 No.-
<P><B>Abstract</B></P> <P>Photo-electrochemical water splitting with hematite photo-anodes under solar irradiation has attracted considerable attention as regards the production of renewable hydrogen energy. However, many challenges remain unresolved, as the full contribution of the catalytic over-layers has not been fully realized. Herein, we incorporate uniform spinel nickel-ferrite over-layers in hematite photo-anodes to obtain an improved understanding of the associated intrinsic changes. We achieve a 1.5-mA/cm<SUP>2</SUP> photo-current density at 1.23V<SUB>RHE</SUB> (RHE: reversible hydrogen electrode) under one-sun illumination conditions, along with a negative shift of 200mV in the onset potential, for NiFe<SUB>2</SUB>O<SUB>4</SUB>-coated Sn-doped hematite photo-anodes. Fundamental electrochemical analyses clearly show that the shift in the onset potential is predominantly due to the enhanced photo-voltage development inside the hematite, rather than being purely caused by the interfacial kinetics. These insights reveal a new direction for fundamental research on photo-anodes towards fabrication of more efficient photo-anode systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spinel ferrite was evaluated for use as a high-performance photo-anode material. </LI> <LI> A nickel-ferrite over-layer was successfully formed on a 1-D hematite nanorod. </LI> <LI> Improved photo-electrochemical performance was achieved through an increase in the photo-voltage and a decrease in the kinetic over-potential. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
ON CERTAIN CLASSES OF MULTIVALENT FUNCTIONS INVOLVING A GENERALIZED DIFFERENTIAL OPERATOR
Selvaraj, Chellian,Selvakumaran, Kuppathai A. Korean Mathematical Society 2009 대한수학회보 Vol.46 No.5
Making use of a generalized differential operator we introduce some new subclasses of multivalent analytic functions in the open unit disk and investigate their inclusion relationships. Some integral preserving properties of these subclasses are also discussed.
Fault-tolerant SMC for Takagi–Sugeno fuzzy systems with time-varying delay and actuator saturation
Selvaraj, Palanisamy,Kaviarasan, Boomipalagan,Sakthivel, Rathinasamy,Karimi, Hamid Reza IET 2017 IET CONTROL THEORY AND APPLICATIONS Vol.11 No.8
<P>This study examines the problem of fault-tolerant sliding mode control (SMC) design subject to actuator saturation for a class of Takagi-Sugeno fuzzy systems with time-varying delay and external disturbances. Our main attention is to propose the fault-tolerant SMC such that for given any initial condition, the system trajectories are forced to reach the sliding surface within a finite time. On the basis of the SM surface and Lyapunov stability theorem, a new set of sufficient conditions in terms of linear matrix inequalities (LMIs) is established to not only guarantee the passivity and asymptotically stability of the resulting closed-loop system in the designed sliding surface, but also cover the issues of actuator saturation and performance constraints. Then, the desired gain matrix of the fault-tolerant SMC is obtained in respect of the previously established LMIs such that the reachability of the predefined sliding surface is ensured. It is worth pointing out that the obtained sufficient conditions can preserve the trade-off between the maximisation of admissible upper bound of time-varying delay and enlarging the estimation about the domain of attraction for the closed-loop system. Eventually, the effectiveness and robustness of the proposed control approach are demonstrated via simulation results.</P>
Selvaraj, D. Edison,Vijayaraj, R.,Sugumaran, C. Pugazhendhi The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.4
In the last decade it has been witnessed significant developments in the area of nano particles and nano scale fillers on electrical, thermal, and mechanical properties of polymeric materials such as resins, varnishes, enamel and bakelites. The electric and thermal properties were more important in the electrical equipments for both steady state and transient state conditions. This paper deals with the characterization of the electric and thermal properties of the pure varnish and zirconia (ZrO<sub>2</sub>) filler mixed varnish. The electric properties such as dielectric loss (tan δ), dielectric constant (ε), dielectric strength and partial discharge voltage were analyzed and detailed for different samples. It was observed that zirconia nano filler mixed varnish has the superior dielectric and thermal properties when compared to those of standard varnish. It has shown that at power frequency the 1wt% nano composite sample has the higher permittivity value when compared to other samples. It has been examined that the 1wt% sample was having higher inception and extinction voltages when compared to other samples. It has been observed that 1wt% sample has higher dielectric strength when compared with other samples. There has been an improvement of thermal property by adding few weight percent of zirconia nano fillers. There was not much variation in glass transition among the nano mixed composites. The weight loss was improved at 1wt% of the zirconia nano fillers.