Impact of heat treatment on mechanical and tribological properties of metal matrix composites of AA6082 T6 with Tin, Zinc and graphite

C. Ramesh,Mohanraj Chandran,K. Chellamuthu,A. Sivakumar 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1

In this research article, the metal matrix composite with AA6082 was formed with mono Tin (5 wt%), Zinc (5 wt%), graphite(5 wt%) and hybrid. The solution heat treatment process and quenching with water and solidification were carried out andresults were compared with AA6082 T6. The different analysis includes mechanical properties (Tensile strength, microhardness), metallurgical properties (SEM and EDX) and tribological property (friction and wear). Micro structure of heattreated AA6082 MMC found with lower defects and fine grain size. Hardness values of heat treated AA6082+Zinc(A6) andhybrid AA6082(A8) found higher than AA6082 T6. The ultimate tensile strength of heat treated AA6082+Zinc(A6) and hybridAA6082(A8) observed higher than AA6082 T6. The wear and friction rate also reduced with heat treated AA6082+Zinc andAA6082 hybrid metal matrix composites.

Atomically Resolved Mapping of Polarization and Electric Fields Across Ferroelectric/Oxide Interfaces by Z‐contrast Imaging

Chang, Hye Jung,Kalinin, Sergei V.,Morozovska, Anna N.,Huijben, Mark,Chu, Ying‐,Hao,Yu, Pu,Ramesh, Ramamoorthy,Eliseev, Evgeny A.,Svechnikov, George S.,Pennycook, Stephen J.,Borisevich, Albina Y WILEY‐VCH Verlag 2011 Advanced Materials Vol.23 No.21

<P><B>Direct atomic displacement mapping at ferroelectric interfaces</B> by aberration corrected scanning transmission electron microscopy(STEM) (a‐STEM image, b‐corresponding displacement profile) is combined with Landau‐Ginsburg‐Devonshire theory to obtain the complete interface electrostatics in real space, including separate estimates for the polarization and intrinsic interface charge contributions. </P>

EXPERIMENTAL STUDIES ON LOW PRESSURE SEMI-DIRECT FUEL INJECTION IN A TWO STROKE SPARK IGNITION ENGINE

M.LOGANATHAN,A.RAMESH 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.2

In this work a two-stroke scooter engine was modified to work with semi direct injection of gasoline at a pressure of 8 bar from an injector in the cylinder barrel pointed toward the cylinder head. The influence of injection timing, injection pressure, spark plug location and air-fuel ratio, on performance, emissions and combustion characteristics has been investigated. In addition, a comparison has been made with manifold injection of gasoline on the same engine at a given speed and various outputs. A significant reduction in HC emissions and fuel consumption with no adverse effects on NOx emissions and combustion stability was observed. A small drop in power and increase in CO emission were observed disadvantages of the new injection system. Injection timing was found to be the most important factor and a balance between reduction in shortcircuited fuel by late injection, and time for mixture preparation by advancing the injection, was found to be essential. In this work a two-stroke scooter engine was modified to work with semi direct injection of gasoline at a pressure of 8 bar from an injector in the cylinder barrel pointed toward the cylinder head. The influence of injection timing, injection pressure, spark plug location and air-fuel ratio, on performance, emissions and combustion characteristics has been investigated. In addition, a comparison has been made with manifold injection of gasoline on the same engine at a given speed and various outputs. A significant reduction in HC emissions and fuel consumption with no adverse effects on NOx emissions and combustion stability was observed. A small drop in power and increase in CO emission were observed disadvantages of the new injection system. Injection timing was found to be the most important factor and a balance between reduction in shortcircuited fuel by late injection, and time for mixture preparation by advancing the injection, was found to be essential.

Photochemical and biochemical responses of heliconia (Heliconia stricta ‘Iris’) to different light intensities in a humid coastal environment

K Nihad,Mukesh K. Berwal,K. Balachandra Hebbar,Ravi Bhat,A. Abdul Haris,S. V. Ramesh 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.6

A field experiment was conducted to evaluate the performance of heliconia (Heliconia stricta ‘Iris’) grown under four levels of photosynthetically active radiation (PAR) in a randomized block design. Photochemical and biochemical parameters were recorded to assess the physiological and biochemical changes in heliconia that accompany varying light intensities. The plants grown under the lowest PAR (30 to 35% of open condition) showed enhanced growth with a higher biomass accumulation, plant height, suckering habit, emergence of flowering shoots, inflorescence yield, and light use efficiency. The leaves exposed to high PAR (open condition) recorded reduction in chlorophyll content (60.8%), chlorophyll index (43.9%), and Fv/Fm (21.4%) compared to values for the leaves exposed to the lowest PAR (30 to 35%). Plant soluble sugars were reduced with the increasing PAR, whereas reducing sugar content was high under fully irradiated conditions but showed a decreasing trend with a reduction in PAR. Total phenolic content and malondialdehyde were lower at 30 to 35% PAR with a reduction in magnitude of 58.4% and 34.8%, respectively, compared to the open condition. Similarly, super oxide dismutase, peroxidase, and polyphenol oxidase activities in the leaf decreased 36.2%, 28.7%, and 23.3%, respectively, from the highest PAR (or open condition) in this range. Improved photochemical and biochemical activities of plants grown under lower light intensities resulted in production of quality inflorescences. Hence, Heliconia stricta ‘Iris’ can be recommended as an intercrop on coconut plantations where the light intensity is low (30 to 35%) for improving the livelihood of farmers.

Thermal evaluation of laser exposures in an<i>in vitro</i>retinal model by microthermal sensing

Choi, Tae Y.,Denton, Michael L.,Noojin, Gary D.,Estlack, Larry E.,Shrestha, Ramesh,Rockwell, Benjamin A.,Thomas, Robert,Kim, Dongsik SPIE - International Society for Optical Engineeri 2014 JOURNAL OF BIOMEDICAL OPTICS Vol.19 No.9

<P>A temperature detection system using a micropipette thermocouple sensor was developed for use within mammalian cells during laser exposure with an 8.6-μm beam at 532 nm. We have demonstrated the capability of measuring temperatures at a single-cell level in the microscale range by inserting micropipettebased thermal sensors of size ranging from 2 to 4 μm into the membrane of a live retinal pigment epithelium (RPE) cell subjected to a laser beam. We setup the treatment groups of 532-nm laser-irradiated single RPE cell and in situ temperature recordings were made over time. Thermal profiles are given for representative cells experiencing damage resulting from exposures of 0.2 to 2 s. The measured maximum temperature rise for each cell ranges from 39 to 73C; the RPE cells showed a signature of death for all the cases reported herein. In order to check the cell viability, real-time fluorescence microscopy was used to identify the transition of pigmented RPE cells between viable and damaged states due to laser exposure.</P>

An Asymptotic finite element method for singularly perturbed higher order ordinary differential equations of convection-diffusion type with discontinuous source term

A. Ramesh Babu,N. Ramanujam 한국전산응용수학회 2008 Journal of applied mathematics & informatics Vol.26 No.5

We consider singularly perturbed Boundary Value Problems (BVPs) for third and fourth order Ordinary Differential Equations(ODEs) of convection-diffusion type with discontinuous source term and a small positive parameter multiplying the highest derivative. Because of the type of Boundary Conditions(BCs) imposed on these equations these problems can be transformed into weakly coupled systems. In this system, the first equation does not have the small parameter but the second contains it. In this paper a computational method named as " An asymptotic finite element method " for solving these systems is presented. In this method we first find an zero order asymptotic approximation to the solution and then the system is decoupled by replacing the first component of the solution by this approximation in the second equation. Then the second equation is independently solved by a fitted mesh Finite Element Method (FEM). Numerical experiments support our theoritical results. We consider singularly perturbed Boundary Value Problems (BVPs) for third and fourth order Ordinary Differential Equations(ODEs) of convection-diffusion type with discontinuous source term and a small positive parameter multiplying the highest derivative. Because of the type of Boundary Conditions(BCs) imposed on these equations these problems can be transformed into weakly coupled systems. In this system, the first equation does not have the small parameter but the second contains it. In this paper a computational method named as " An asymptotic finite element method " for solving these systems is presented. In this method we first find an zero order asymptotic approximation to the solution and then the system is decoupled by replacing the first component of the solution by this approximation in the second equation. Then the second equation is independently solved by a fitted mesh Finite Element Method (FEM). Numerical experiments support our theoritical results.

Genomic Heterogeneity of Chicken Populations in India

Rajkumar, Ullengala,Gupta, B. Ramesh,Reddy, A. Rajasekhara Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.12

A comprehensive genome profiling study was undertaken based on automated genotyping and analysis of 20 microsatellite markers that involved 155 birds representing eight different populations. The distribution of microsatellite markers in each of these breeds helped us to decipher genetic heterogeneity, population genetic structure and evolutionary relationships of the present day chicken populations in India. All the microsatellite loci utilized for the analysis were polymorphic and reasonably informative. A total of 285 alleles were documented at 20 loci with a mean of 14.25 alleles/locus. A total of 103 alleles were found to be population/strain specific of which, only 30 per cent had a frequency of more than 10. The mean PIC values ranged from 0.39 for the locus ADL158 to 0.71 for loci MCW005 or ADL267 across the genomes and 0.55 in Dahlem Red to 0.71 in Desi (non-descript), among the populations. The overall mean expected and observed heterozygosity estimates for our populations were 0.68 and 0.64, respectively. The overall mean inbreeding coefficients (FIS) varied between -0.05 (Babcock) and 0.16 (Rhode Island Red). The pairwise FST estimates ranged from 0.06 between Aseel and Desi (non-descript) to 0.14 between Dahlem Red and Babcock. The Nei's genetic distance varied from 0.30 (WLH-IWD and WLH-IWF) to 0.80 (Dahlem Red and Babcock. Phylogenetic analysis grouped all the populations into two main clusters, representing i) the pure breeds, Dahlem Red and Rhode Island Red, and ii) the remaining six populations/strains. All the chicken populations studied were in the state of mild to moderate inbreeding except for commercial birds. A planned breeding is advised for purebreds to revive their genetic potential. High genetic diversity exists in Desi (non-descript), local birds, which can be exploited to genetically improve the birds suitable for backyard poultry.

An Explainable Deep Learning Approach for Oral Cancer Detection

Babu P. Ashok,Rai Anjani Kumar,Ramesh Janjhyam Venkata Naga,Nithyasri A.,Sangeetha S.,Kshirsagar Pravin R.,Rajendran A.,Rajaram A.,Dilipkumar S. 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

With a high death rate, oral cancer is a major worldwide health problem, particularly in low- and middle-income nations. Timely detection and diagnosis are crucial for efective prevention and treatment. To address this challenge, there is a growing need for automated detection systems to aid healthcare professionals. Regular dental examinations play a vital role in early detection. Transfer learning, which leverages knowledge from related domains, can enhance performance in target categories. This study presents a unique approach to the early detection and diagnosis of oral cancer that makes use of the exceptional sensory capabilities of the mouth. Deep neural networks, particularly those based on automated systems, are employed to identify intricate patterns associated with the disease. By combining various transfer learning approaches and conducting comparative analyses, an optimal learning rate is achieved. The categorization analysis of the reference results is presented in detail. Our preliminary fndings demonstrate that deep learning efectively addresses this challenging problem, with the Inception-V3 algorithm exhibiting superior accuracy compared to other algorithms.

Density Functional Theory Study on the Cross-Linking of Mussel Adhesive Proteins

Matin, Mohammad A.,Chitumalla, Ramesh Kumar,Lim, Manho,Gao, Xingfa,Jang, Joonkyung American Chemical Society 2015 The Journal of physical chemistry B Vol.119 No.17

<P>The water-resistant adhesion of mussel adhesive proteins (MAPs) to a wet surface requires a cross-linking step, where the catecholic ligands of MAPs coordinate to various transition-metal ions. Fe(III), among the range of metal ions, induces particularly strong cross-linking. The molecular details underlying this cross-linking mediated by transition-metal ions are largely unknown. Of particular interest is the metal–ligand binding energy, which is the molecular origin of the mechanical properties of cross-linked MAPs. Using density functional theory, this study examined the structures and binding energies of various trivalent metal ions (Ti–Ga) forming coordination complexes with a polymeric ligand similar to a MAP. These binding energies were 1 order of magnitude larger than the physisorption energy of a catechol molecule on a metallic surface. On the other hand, the coordination strength of Fe(III) with the ligand was not particularly strong compared to the other metal ions studied. Therefore, the strong cross-linking in the presence of Fe(III) is ascribed to its additional ability as an oxidant to induce covalent cross-linking of the catecholic groups of MAPs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2015/jpcbfk.2015.119.issue-17/acs.jpcb.5b01152/production/images/medium/jp-2015-011524_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b01152'>ACS Electronic Supporting Info</A></P>

Closed-Loop Transmit Diversity Techniques for Small Wireless Terminals and Their Performance Assessment in a Flat Fading Channel

Raqibul Mostafa,Ramesh C. Pallat,Uwe Ringel,Ashok A. Tikku,Jeffrey H. Reed 한국전자통신연구원 2012 ETRI Journal Vol.34 No.3

Closed-loop transmit diversity is considered an important technique for improving the link budget in the third generation and future wireless communication standards. This paper proposes several transmit diversity algorithms suitable for small wireless terminals and presents performance assessment in terms of average signal-to-noise ratio (SNR) and outage improvement,convergence, and complexity of operations. The algorithms presented herein are verified using data from measured indoor channels with variable antenna spacing and the results explained using measured radiation patterns for a two-element array. It is shown that for a two-element array, the best among the proposed techniques provides SNR improvement of about 3 dB in a tightly spaced array (inter-element spacing of 0.1wavelength at 2 GHz) typical of small wireless devices. Additionally, these techniques are shown to perform significantly better than a single antenna device in an indoor channel considering realistic values of latency and propagation errors. Closed-loop transmit diversity is considered an important technique for improving the link budget in the third generation and future wireless communication standards. This paper proposes several transmit diversity algorithms suitable for small wireless terminals and presents performance assessment in terms of average signal-to-noise ratio (SNR) and outage improvement,convergence, and complexity of operations. The algorithms presented herein are verified using data from measured indoor channels with variable antenna spacing and the results explained using measured radiation patterns for a two-element array. It is shown that for a two-element array, the best among the proposed techniques provides SNR improvement of about 3 dB in a tightly spaced array (inter-element spacing of 0.1wavelength at 2 GHz) typical of small wireless devices. Additionally, these techniques are shown to perform significantly better than a single antenna device in an indoor channel considering realistic values of latency and propagation errors.