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Optical soliton propagation in erbium-doped fibre with variable dispersion and nonlinear effects
Uthayakumar, A.,Mahalingam, A.,Han, Young-Geun,Lee, Sang Bae Taylor Francis 2006 JOURNAL OF MODERN OPTICS - Vol.53 No.11
<P> We propose a coupled system of generalized nonlinear Schrodinger and Maxwell-Bloch equations with variable coefficients which describes propagation of an optical soliton in an inhomogeneous nonlinear waveguide doped with two-level resonant atoms. The Lax pair of this model is derived using the Ablowitz-Kaup-Newell-Segur (AKNS) formalism. The one-soliton solution is constructed through a Darboux-Backlund transformation (BT). The coupled system is found to allow soliton propagation. We explain the soliton control by the effect of distributed amplification with varying group velocity dispersion, nonlinearity and gain or loss parameters.</P>
Precision Machining of an Aluminum Alloy Piston Reinforced with a Cast Iron Insert
Marimuthu Uthayakumar,Gopalakrishnan Prabhakaran,Sivanandham Aravindan,Jonna Venkata Sivaprasad 한국정밀공학회 2009 International Journal of Precision Engineering and Vol.10 No.1
Bimetallic pistons consisting of aluminum alloy reinforced with a cast iron (CI) insert are used to reduce the weight and improve the wear resistance of pistons. A major problem with machining such bimetallic pistons is producing the desired shape with minimal cutting forces and without damaging the bonding registry. The objective of this paper is to determine the optimal cutting parameters (cutting speed, feed, and depth of cut) for turning bimetallic pistons. When machining, we wish to obtain optimal values of the cutting forces and a better surface integrity while maintaining the required surface finish. Experiments were conducted following Taguchi’s parameter design approach using a cubic boron nitride tool for the machining. The results indicate that the process parameters affected the mean and variance of the cutting force at the Al-CI interface of the piston. The Al-CI interface was examined using an ultrasonic piston bond tester after machining to assure the bond quality. The surface roughness of the components was measured with a surface roughness tester. A mathematical model was developed using the Systat 12.0 software package to establish the relationship between the input quantities (speed, feed, and depth of cut) and the output data (cutting force). The output data of the mathematical model were compared with the experimental results. The results from the Taguchi robust design concept were compared with the results obtained from a nonconventional Genetic Algorithm optimization technique.
띠뚜말라이쿠마란,고태조,쿠르니아완렌디,Changping Li,M. Uthayakumar 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8
This study discusses the development of an Adaptive neuro–fuzzy inference system (ANFIS) model for determining the surface roughness (Ra) during machining of multidirectional woven fabric Carbon fiber reinforced plastics (CFRP) using Abrasive waterjet machining (AWM). Three variable input parameters—Jet pressure (JP), Traverse speed (TS), and Standoff distance (SOD)—were selected to assess the roughness of the CFRP along the traverse direction of the cut surface. The experimental results show that a lower JP deteriorated the finish by creating surface rupture. On the other hand, a poor surface finish was observed in the case of machining at higher TS and SOD. Further, the developed ANFIS model was used to validate the results and it was found that the predicted values were in good agreement with a 95 % confidence level. It was also evident that the ANFIS technique is helpful for better prediction of the experimental data with minimum error. Finally, the cut surface morphology was analyzed using a 3D non-contact surface profilometer and the results are discussed.
Kumaran, S. Thirumalai,Ko, Tae Jo,Uthayakumar, M.,Islam, Md. Mofizul Elsevier 2017 Journal of Alloys and Compounds Vol.724 No.-
<P><B>Abstract</B></P> <P>In the present work, two different carbon fiber-reinforced plastics (CFRP), namely, unidirectional (UD) and UD with a woven fabric surface, were selected in order to investigate the surface roughness as a result of machining with an abrasive water jet machine (AWJM). The experiments were conducted based on an L27 orthogonal array by varying the process parameters such as jet pressure (JP), traverse speed (TS), and standoff distance (SOD). Regression models were developed to predict the correlation between the input parameters and the surface roughness for each composite. The experimental results showed that increased pressure with lower TS and SOD produced a good surface finish on the composites. Very low roughness was achieved when machining the UD with woven fabric surface CFRP composite. The developed regression models indicated the significance of the design (at a 95% confidence level) with reduced error. The JP followed by the SOD were found to be the major parameters affecting the surface roughness. Finally, the deformation, delamination, and machined surface morphology were studied using a non-contact three-dimensional surface measurement system and scanning electron microscopy (SEM) images.</P>
Santhosh, Padmanabhan,Manesh, Kalayil Manian,Lee, Se-Hee,Uthayakumar, Sivaperumal,Gopalan, Anantha Iyengar,Lee, Kwang-Pill Royal Society of Chemistry 2011 The Analyst Vol.136 No.8
<P>In the present communication, a novel composite nanofibrous electrode is developed for the detection of superoxide anion (O<SUB>2</SUB>˙<SUP>−</SUP>) in phosphate buffered saline (PBS). The composite fiber electrode is fabricated by dispersing gold nanoparticles onto poly(methyl methacrylate) (PMMA)–polyaniline (PANI) core–shell electrospun nanofibers. The constructed architecture is proven to be a favorable environment for the immobilization of the enzyme, superoxide dismutase (SOD). Direct electron transfer is achieved between SOD and the electrode with an electron transfer rate constant of 8.93 s<SUP>−1</SUP>. At an applied potential of +300 mV, PMMA/PANI–Au<SUB>nano</SUB>/SOD–ESCFM shows highly sensitive detection of O<SUB>2</SUB>˙<SUP>−</SUP>. In addition to this, quantification of different activities of SOD is realized at PMMA/PANI–Au<SUB>nano</SUB>/SOD–ESCFM. These analytical features offer great potential for construction of the third-generation O<SUB>2</SUB>˙<SUP>−</SUP> biosensor.</P> <P>Graphic Abstract</P><P>A novel composite nanofibrous electrode is developed for the detection of superoxide anion in phosphate buffer saline. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0an00616e'> </P>
R.V. Mangalaraja,S. Ananthakumar,Kasimayan Uma,Romel M. Jiménez,S.Uthayakumar,Marta López,Carlos P. Camurri 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.1
An in-situ sulphated-combustion synthesis is reported to obtain gadolinium [Ce0.9Gd0.1O1.95] and samarium [Ce0.9Sm0.1O1.95]doped ceria electrolytes for solid oxide fuel cells (SOFCs). Nitrate precursors of cerium, gadolinium and samarium reactants were mixed homogenously with a citric acid fuel with an in-situ addition of 10 and 20 mol% ammonium sulphate [(NH4)2SO4]. The mixture was combusted at 500 oC and subsequently calcined at 700 oC. The influence of the sulphate addition on the morphology of ceria particles has been analyzed. It is seen that the in-situ SO42- ions highly favors the nucleation and growth of doped ceria electrolytes on a nanometer scale with an added advantage of improved crystallinity. TEM analysis indicates loosely agglomerated and nearly spherically shaped ceria nano particles with a maximum particle size of 20 nm.
Rotary ultrasonic machining of woven CFRP composite in a cryogenic environment
Thirumalai Kumaran, S.,Ko, Tae Jo,Li, Changping,Yu, Zhen,Uthayakumar, M. ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.698 No.-
<P><B>Abstract</B></P> <P>In the present study, rotary ultrasonic machining (RUM) was adopted to perform drilling of carbon fiber reinforced plastics (CFRP) in a cryogenic environment. An L27 orthogonal array was selected to conduct experiments by varying the spindle speed (denoted as N), feed rate (denoted as f), and ultrasonic power (denoted as P). The thrust force (denoted as Fz), exit burr area, and surface roughness (denoted as Ra) were measured to evaluate the machining performance. The influence of process parameters and the regression model were derived for each output quality response. Additionally, multi-objective optimization was performed using desirability analysis, and the predicted levels were used for confirmation. The results indicated that the feed rate (f) contributed more to the thrust force (Fz) by 45.85% and a maximum thrust force was recorded at 0.1 mm/rev. A decrease in spindle speed (N) was associated with an increase in feed rate (f) and ultrasonic power (P), and it resulted in minimum exit burr area. The influence of ultrasonic power (P) was highly significant in reducing burrs with a contribution of 52.45%. Conversely, the surface roughness (Ra) of the drill holes decreased at 3000 rpm, and this was attributed to the brittle fracture of the fibers at a lower temperature. Both N (30.88%) and f (30.83%) had an equal influence on producing a better surface finish in the drill holes. Furthermore, the predicted optimal settings were used to validate the results and were found to be within 95% confidence and prediction interval. Finally, the microscopic images of tool wear, burr formation, and drill hole surface morphology were analyzed and examined.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Prediction of regression model for RUM of CFRP in a cryogenic environment. </LI> <LI> Output responses such as thrust force, burr area and roughness are investigated. </LI> <LI> The adequacy of an ANOVA model is checked for each output response. </LI> <LI> Optimization is performed by desirability analysis and the results are validated. </LI> <LI> Tool wear, burr formation, and drill hole surface morphology are analyzed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>