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Analytical Models to Predict Power Harvesting with Piezoelectric Transducer
Raghava Raju Muppala,K. Padma Raju,Nam Mee Moon,Baek Ho Jung 한국전자파학회JEES 2008 Journal of Electromagnetic Engineering and Science Vol.8 No.1
Advances in low power design open the possibility to harvest energy from the environment to power electronic circuits. Electrical energy can be harvested from piezoelectric transducer. Piezoelectric materials can be used as mechanisms to transfer mechanical energy usually vibrating system into electrical energy that can be stored and used to power other devices. Micro- to milli-watts power can be generated from vibrating system. We developed definitive and analytical models to predict the power generated from a cantilever beam attached with piezoelectric transducer. Analytical models are pin-force method, enhanced pin-force method and Euler-Bernoulli method. Harmonic oscillations and random noise will be the two different forcing functions used to drive each system. It has been selected the best model for generating electric power based upon the analytical results obtained.
Sirangi, Subash,Jogam, Phanikanth,Nemali, Gandhi,Ajmeera, Ragan,Abbagani, Sadanandam,Raju, Vatsavaya S. The Korean Society of Plant Biotechnology 2020 JOURNAL OF PLANT BIOTECHNOLOGY Vol.47 No.4
The genetic diversity of two subpopulations of Corynandra chelidonii, one of terrestrial and the other of aquatic environments, was measured with molecular markers, such as start codon targeted (SCoT), inter simple sequence repeats (ISSR), and random amplification of polymorphic DNA (RAPD). The traditional morphological traits such as habitat, habit, leaf morphology, the colour of the sepals and petals, number of stamens, and seed morphology formed the base for their realization as two varieties, C. chelidonii var. pallae and C. chelidonii var. chelidonii. The polymorphism between the two variants was 100% with the primers SCoT-2 and OPA-1 and 4, while maximum polymorphism was detected with ISSR-2, SCoT-3, and OPA-3. The study used, for the first time, more than one molecular marker to assess the genetic variation underscoring the morphological variation in Corynandra chelidonii (L.f.) Cochrane & Iltis. The study justifies the recognition of the two subpopulations of Corynandra chelidonii from aquatic and terrestrial environments as two distinct varieties, C. chelidonii var. pallae (Reddy & Raju) V.S.Raju and C. chelidonii var. chelidonii, respectively, based on the traditional taxonomic evidence.
Sintering additives for SiC based on the reactivity: A review
Raju, Kati,Yoon, Dang-Hyok Elsevier 2016 CERAMICS INTERNATIONAL Vol.42 No.16
<P><B>Abstract</B></P> <P>Silicon carbide (SiC) is one of the most attractive materials for high temperature applications, being used in many areas, such as gas turbines, heat exchangers, and space shuttles, because of its excellent strength, oxidation resistance and chemical stability at high temperatures. Moreover, SiC and its composites are being considered as structural materials for advanced fission reactors and future fusion reactors owing to its additional low induced radioactivity under neutron irradiation conditions. On the other hand, pure SiC can only be densified by sintering at high temperatures and pressures because of its high covalent bonding nature and low self-diffusivity. Therefore, the addition of sintering additives is essential for enhancing the densification of SiC. This paper reviews the criteria for the selection of effective SiC sintering additives based on the Gibbs free energy to predict the reactivity between the sintering additive and SiC, particularly for liquid phase sintering at 1700–1900°C. The thermodynamic simulation was verified by offering the experimental results for various types of sintering additives, such as main group metals, metal oxides, and rare earth elements. This review suggests a guideline for the selection of sintering additives for SiC.</P>
Raju, K.,Muksin,Yoon, D.H. Ceramurgica ; Elsevier Science Ltd 2016 CERAMICS INTERNATIONAL Vol.42 No.14
This paper reports the effectiveness of a Ag-10wt% CuO braze filler for the joining of dense Ce<SUB>0.9</SUB>Gd<SUB>0.1</SUB>O<SUB>2-δ</SUB>-La<SUB>0.6</SUB>Sr<SUB>0.4</SUB>Co<SUB>0.2</SUB>Fe<SUB>0.8</SUB>O<SUB>3-δ</SUB> (GDC-LSCF) dual-phase ceramics for the oxygen transport membrane applications. Brazing was performed at 1050<SUP>o</SUP>C for 30min in air. The microstructure of the ceramic-filler-ceramic interfaces of the polished cross-sectional areas and the elemental distribution were examined. The results indicated that the Ag-10wt% CuO braze filler ensured reliable and compact joining without the formation of cracks and voids at the joining interface. The room temperature mechanical shear strengths were 59.3 and 40.2MPa for the as-brazed and isothermally aged joints at 800<SUP>o</SUP>C for 24h in air, respectively.
Raju, Arathy,Nair, Shantikumar V.,Lakshmanan, Vinoth-Kumar IET 2017 IET nanobiotechnology Vol.11 No.7
<P>Phytomedicine research received tremendous attention for novel therapeutic agent due to their safety and low cost. We assessed a novel nanoformulation of Biophytum sensitivum (BS), natural flavonoids for their improved efficacy and superior bioavailability against crude extract for prostate cancer cells (PC3). We prepared a nanomedicine of BS by nanoprecipitation method and size analysis via DLS and SEM revealed a range of 100-118nm and surface zeta potential as -9.77mV. FTIR was performed to evaluate functional for presence of carbonyl and aromatic rings, respectively. Human PC3 cells showed concentration at 0.5, 0.8, and 1mg/ml dependent cytotoxicity 22, 39, and 56% for 24h, whereas 43, 41, and 67% for 48h of BS nanomedicine compared with crude 11, 22, and 53% for 24h and 38, 31, and 60% for 48h, respectively. Haemocompatibility of BS nanomedicine at the concentration of 0.5, 0.8, and 1mg/ml did not show blood aggregation. Cellular uptake was confirmed using rhodamine-conjugated BS nanomedicine for 48h. Interestingly, BS nanomedicine 1 mg/ml decreases the nitrite productions in PC3 cells. Collectively, BS nanomedicine has the potential anti-cancer agents with biocompatible and enhanced efficacy can be beneficial for the treatment of prostate cancer</P>
Raju, G. Seeta Rama,Pavitra, E.,Bharat, L. Krishna,Rao, Gattupalli Manikya,Jeon, Tae-Joon,Huh, Yun Suk,Han, Young-Kyu Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.12
<P><B>Abstract</B></P> <P>Upconversion Sr<SUB>2</SUB>(Gd<SUB>.98-<I>x</I> </SUB>Er<SUB>.02</SUB>Yb<SUB> <I>x</I> </SUB>)<SUB>8</SUB>Si<SUB>6</SUB>O<SUB>26</SUB> (SGSO:2Er<SUP>3+</SUP>/<I>x</I>Yb<SUP>3+</SUP>) phosphor materials were synthesized using a citrate sol-gel process. X-ray diffraction patterns confirmed their hexagonal structure. Field emission scanning electron microscopy images of SGSO:2Er<SUP>3+</SUP>/<I>x</I>Yb<SUP>3+</SUP> phosphors depicted submicron particles. The enhanced upconversion luminescence properties of SGSO:2Er<SUP>3+</SUP>/<I>x</I>Yb<SUP>3+</SUP> phosphors were analysed as a function of Yb<SUP>3+</SUP> ion concentration and laser power. The energy transfer induced enhanced emission of the Er<SUP>3+</SUP>/ Yb<SUP>3+</SUP> ions co-doped SGSO phosphors was ascribed to multi-phonon relaxation. The calculated chromaticity coordinates of the SGSO:2Er<SUP>3+</SUP>/<I>x</I>Yb<SUP>3+</SUP> phosphors showed emissions could be tuned by changing Yb<SUP>3+</SUP> ion concentration. Optimized sample exhibited the chromaticity coordinate values near to the ultra-high definition television standard green emission coordinates.</P>
Joining of metal-ceramic using reactive air brazing for oxygen transport membrane applications
Raju, K.,Muksin,Kim, S.,Song, K.s.,Yu, J.H.,Yoon, D.H. Elsevier Ltd 2016 Materials & Design Vol.109 No.-
<P>This study examined the joining of dense Ce0.9Gd0.1O2 (-) (delta)-La0.6Sr0.4Co0.2Fe0.8O3 (-) (delta) (GDC-LSCF) ceramics to high temperature metal alloys for the fabrication of multilayered oxygen transport membrane (OTM) stacks. Reactive air brazing using a silver-based paste was performed at 1050 degrees C for 30 min in air to join GDC-LSCF/high temperature alloys, such as AISI 310S, Inconel 600 and Crofer 22 APU. The effects of the various filler materials, including CuO, GDC, LSCF, and GDC-LSCF mixture, in the Ag paste were also examined. The Ag-10 wt% CuO braze filler ensured in a reliable and compact joining without the formation of cracks and voids at the joining interface, while the addition of other ceramic fillers resulted in incomplete joining. Although none of the GDC-LSCF/metal alloy joints showed gas leakage at room temperature, the GDC-LSCF/Crofer joint only maintained the gas-tightness up to 800 degrees C under pressurized air up to 7 bars, which was explained by the microstructural rigidness of the oxide layer formed on the filler/alloy interface at high temperatures. This was supported by the minimal decrease in shear strength of the GDC-LSCF/Crofer joint, which was 91.1 and 88.3 MPa for the as-brazed and isothermally aged joint at 800 degrees C for 24 h in air, respectively. (C) 2016 Published by Elsevier Ltd.</P>