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SENSITIVIY OF A NANOCANTILEVER-BASED MASS SENSOR
K. PRABAKAR,J. JAYAPANDIAN,A. K. TYAGI,C. S. SUNDAR,BALDEV RAJ 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2010 NANO Vol.5 No.1
In the present work, mass and position sensitivity of a nanocantilever is simulated using finite element analysis. Changes in resonant frequency of various modes of a polysilicon cantilever, with a gold coating of different thickness, area, and spatial distribution is simulated. It is found that for a uniform increase in gold coating thickness, torsional mode gives an order higher mass sensitivity than vertical bending and lateral bending modes. In other cases, sensitivity is highly dependent on the position of the coating and is explained on the basis of flexural rigidity. Apart from this, simulations were performed for a point mass (gold cube) loading at various positions along the length and width axis of the cantilever. Further, for localized mass loading, cantilever was tailored for enhanced sensitivity. It is found that by introducing a step discontinuity in thickness of the cantilever, the mass sensitivity increases by two orders of magnitude and it depends on the position of step from free end, step thickness, and step width.
Free vibration of anti-symmetric angle-ply plates with variable thickness
Javed, S.,Viswanathan, K.K.,Aziz, Z.A.,Prabakar, K. Applied Science Publishers ; Elsevier 2016 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.137 No.-
Free vibration of anti-symmetric angle-ply plates with variable thickness is analysed using spline function approximation including the effect of shear deformation. The equations of motion for the plate are derived using the theory of Yang, Norris and Stavsky. Assuming the solution in a separable form, a system of coupled differential equations in displacement and rotational functions are obtained and these functions are approximated by Bickley-type splines of order three. A generalised eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector of spline coefficients. Two and four layered plates consisting of two different materials and plies comprising of same as well as different materials for two different boundary conditions are analysed. The effect of material properties, ply orientation, number of lay ups, aspect ratio and coefficients of thickness variations on the frequency parameter are presented. The accuracy of the result is ascertained by convergence and comparative study.
Jeong, M. S.,Son, M. K.,Kim, S. K.,Park, S.,Prabakar, K.,Kim, H. J. SPRINGER SCIENCE AND BUSINESS MEDIA 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.3
Cadmium sulfide (CdS) quantum dots (QDs) were adsorbed on a titanium dioxide (TiO2) nanoporous film by successive ionic layer adsorption and reaction (SILAR) method with different adsorption times to study the influences of different SILAR adsorption times on CdS quantum dot-sensitized solar cells (QDSCs). The optical properties of CdS sensitized TiO2 films were studied by scanning electron microscopy and UV-Vis absorbance spectroscopy. The particle size of the CdS QDs was approximated using the effective mass approximation theory from the absorbance spectra. The photovoltaic characteristics of the CdS QDSCs were analyzed by I-V characteristics and electrochemical impedance spectroscopy under air mass 1.5 illumination. As a result, the particle size of the CdS QDs became larger and light harvesting was enhanced with increasing SILAR adsorption time. The maximum photovoltaic conversion efficiency of the CdS QDSCs (1.86%) was obtained at the SILAR adsorption time of 30 min with the highest short circuit current density and lowest charge transfer resistance.
Shin, I.,Seo, H.,Son, M.K.,Kim, J.K.,Prabakar, K.,Kim, H.J. Elsevier 2010 CURRENT APPLIED PHYSICS Vol.10 No.3
Dye-sensitized solar cell (DSC) consists of a TiO<SUB>2</SUB> nano film of the photo electrode, dye molecules on the surface of the TiO<SUB>2</SUB> film, an electrolyte layer and a counter electrode. Among these, the nano porous TiO<SUB>2</SUB> film plays an important role as the photo electrode in DSC because it adsorbs a large number of the dye molecules which provide electrons. Therefore, the condition of the TiO<SUB>2</SUB> film affects the cell performance such as current density (J<SUB>sc</SUB>), open circuit voltage (V<SUB>oc</SUB>) and fill factor (FF). The thickness of TiO<SUB>2</SUB> film is one of these conditions. Its variation influences on the internal impedances of DSC related to the electron transport. In this study, we analyzed the characteristics of DSC with the different thicknesses of TiO<SUB>2</SUB> film by using electrochemical impedance spectroscopy (EIS) in details. As a result, it was demonstrated that the variation of the TiO<SUB>2</SUB> thickness has an effect on the electron transport in the DSC. Finally, the TiO<SUB>2</SUB> thickness is optimized for the best performance of DSC.
Free vibration of layered cylindrical shells filled with fluid
Nurul Izyan, M. D.,Viswanathan, K. K.,Aziz, Z. A.,Prabakar, K. Springer Science + Business Media 2016 Applied mathematics and mechanics Vol.37 No.6
<P>The vibration of the layered cylindrical shells filled with a quiescent, incompressible, and inviscid fluid is analyzed. The governing equations of the cylindrical shells are derived by Love's approximation. The solutions of the displacement functions are assumed in a separable form to obtain a system of coupled differential equations in terms of the displacement functions. The displacement functions are approximated by Bickley-type splines. A generalized eigenvalue problem is obtained and solved numerically for the frequency parameter and an associated eigenvector of the spline coefficients. Two layered shells with three different types of materials under clamped-clamped (C-C) and simply supported (S-S) boundary conditions are considered. The variations of the frequency parameter with respect to the relative layer thickness, the length-to-radius ratio, the length-to-thickness ratio, and the circumferential node number are analyzed.</P>
Richard Prabakar, S.J.,Han, S.C.,Jeong, J.,Sohn, K.S.,Pyo, M. Elsevier Ltd 2017 Materials & Design Vol.118 No.-
<P>Herein is the first use of a CoSn(OH)(6)/graphene composites as a high-performance anode in lithium ion batteries (LIBs). CoSn(OH)(6) alone is found to be electrochemically active and to possess electrochemical properties that are superior to those displayed in its dehydrated form (CoSnO3). In contrast to the formation of 3Li(2)O in CoSnO3 during the first discharge (CoSnO3 + 6Lit(+) 6e(-) -> Co + Sn + 3Li(2)O), the production of 6 mol of LiOH in CoSn(OH)(6) (CoSn(OH)(6) + 6Li(+) + 6e(-) -> Co + Sn + 6LiOH) seems to provide nanometric Co/Sn particles with more efficient reversibility for the subsequent Li+-insertion/de-insertion via conversion/alloy reactions. The electrochemical performance of CoSn(OH)(6) is further improved when composited with graphenes. This is accomplished by electrostatically combining negatively charged Co2+/Sn2+-anchored graphene oxide (GO) with positively charged amine-functionalized graphene (GN) in a solution. The subsequent hydrothermal reaction produces CoSn(OH)(6) nanocubes that are tightly held by graphene sheets (GO/CS/GN). The GO/CS/GN delivers unprecedentedly high capacity and excellent cyclability (discharge capacities of 1475 mAh.g(-1) for the 100th charge/discharge (C/D) cycles at a 0.1 A.g(-1)). In contrast to the comparison materials (CoSnO3/graphene composites) the rate performance is also remarkable, delivering a capacity of 650 mAh.g(-1) at 2.0 at A.g(-1). (C) 2017 Published by Elsevier Ltd.</P>
Banyan Root Structured Mg-Doped ZnO Photoanode Dye-Sensitized Solar Cells
Raj, C. Justin,Prabakar, Kandasamy,Karthick, S. N.,Hemalatha, K. V.,Son, Min-Kyu,Kim, Hee-Je American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.6
<P>We report a peculiar banyan root like Mg-doped ZnO photoanode to result in high electron transport, retardation of interfacial charge recombination, improved light harvesting efficiency, and overall enhanced photovoltaic performance of dye-sensitized solar cells (DSSC). DSSC based on a 5 mol % Mg-doped ZnO electrode of very low thickness, ∼4 μm, gained an improved short-circuit current density of 9.98 mAcm<SUP>–2</SUP>, open-circuit photo voltage of 0.71 V, fill factor of 0.58, and overall conversion efficiency of 4.11% under 1 sun illumination.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-6/jp308847g/production/images/medium/jp-2012-08847g_0011.gif'></P>