Experimental and Computational Studies on the Reentry Capsule Aerodynamics with a Flap

Senthil Kumar,J K Prasad,Kim H D 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5

Flow field around a typical reentry capsule has been investigated adopting experiments and computations. The reentry capsule has the flap which could be useful to obtain control force. All the studies have been made at a free stream Mach number of 2 and Reynolds number of 30 X 106. Experiments consisted of schlieren flow visualization and measurement of axial force only. Three dimensional computation has been made using FLUENT and adopting k-ω turbulence model. Effect of angle of attack and flap angle has been obtained. Based on present study, it is observed the flap increases the axial force.

UV-Blue Light Emission from ZnO Nanoparticles

Obuliraj Senthilkumar,Kazuki Yamauchi,Kasilingam Senthilkumar,Takahiro Yamamae,Yasuhisa Fujita,Naoki Nishimoto 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1

Gas evaporation was employed to prepare nitrogen-doped ZnO nanoparticles, which showed in- tense UV/blue emission (380 nm) at room temperature. The thin lms were deposited by dip coating with nanoparticles dispersed in isopropanol and water. The PL spectrum showed dominant acceptor bound excitons around 371 nm at low temperatures, which was due to the substitution of nitrogen acceptors in oxygen sites. Nitrogen doping was also conrmed from Raman spectroscopy, which showed a nitrogen-related local vibrational mode (LVMN) at 583 cm-1. Gas evaporation was employed to prepare nitrogen-doped ZnO nanoparticles, which showed in- tense UV/blue emission (380 nm) at room temperature. The thin lms were deposited by dip coating with nanoparticles dispersed in isopropanol and water. The PL spectrum showed dominant acceptor bound excitons around 371 nm at low temperatures, which was due to the substitution of nitrogen acceptors in oxygen sites. Nitrogen doping was also conrmed from Raman spectroscopy, which showed a nitrogen-related local vibrational mode (LVMN) at 583 cm-1.

Synergistic effect of quercetin and silver nanoparticles on HeLa cancer cells

Senthilkumar KALIMUTHU,Manivasagan PANCHANATHAN,Jayachandran VENKATESAN,Se-Kwon KIM 한국생물공학회 2013 한국생물공학회 학술대회 Vol.2013 No.10

Methyl Isocyanate and Carcinogenesis: Bridgeable Gaps in Scientific Knowledge

Senthilkumar, Chinnu Sugavanam,Sah, Nand Kishore,Ganesh, Narayanan Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

Methyl isocyanate may have a role in cancer etiology, although the link is unclear. There is evidence in the literature that it can induce cancer in animals but the carcinogenic potency is weak. Pheochromocytoma of adrenal medulla and acinar cell tumors of pancreas have been observed in methyl isocyanate exposed animals. Conversely, emerging data from population-based epidemiological studies are contradictory since there is no evidence of such cancers in methyl isocyanate exposed humans. Recently, we reported a high prevalence of breast and lung cancers in such a population in Bhopal. In vitro findings appearing in the latest scientific literature suggest that genomic instability is caused by methyl isocyanate analogs in lung, colon, kidney, ovary epithelial cells, and that hepatocytes may undergo oncogenic transformation, have obvious implications. The conflicting information prompted us to present this update over the last three decades on methyl isocyanate-induced cancers after an extensive literature search using PubMed. While the pertinent literature remains limited, with a scarcity of strong laboratory analyses and field-epidemiological investigations, our succinct review of animal and human epidemiological data including in vitro evidences, should hopefully provide more insight to researchers, toxicologists, and public health professionals concerned with validation of the carcinogenicity of methyl isocyanate in humans.

Investigations on PD Characteristics of Thermal aged Palm and Corn Oil for Power Transformer Insulation Applications

Senthilkumar, S.,Karthik, B.,Chandrasekar, S. The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

Partial discharge (PD) detection plays a major role in the life time assessment of liquid insulation in power transformers. Many research works are being carried out to replace conventional mineral oil insulation in transformers by vegetable oils. It is necessary to understand the PD characteristics of vegetable oils before recommending them as an alternate for mineral oil. In this paper, the breakdown strength and PD characteristics of palm and corn oil were investigated in both unaged and thermally aged conditions. Laboratory experiments were performed as per IEC test procedures. PD signals were measured using wide band detection system. Phase resolved PD pattern of vegetable oils and mineral oil were compared. Effect of increase in voltage stress on the PD pattern of palm and corn oil were studied. Time and frequency domain analysis of PD pulses at needle-plane electrode configuration was carried out. Statistical analysis of PD pattern i.e. skewness and shape parameter variations with respect to applied thermal stress were also carried out. From the results, it is observed that palm and corn oils have better breakdown strength and PD characteristics even under long-term thermal stress and hence they can be used for power transformer applications.

Understanding the molecular interaction and relaxation findings in amphiphilics on solution state using TDR

Senthilkumar P.,Vinoth K.,Maria Sylvester M.,Karunakaran D.J.S.Anand,Deshmukh Avadhut Ramrao,Hudge Pravin,Ganesh T.,Kumbharkhane A.C. 한국물리학회 2022 Current Applied Physics Vol.38 No.-

The dielectric behavior of stearic acid in 1,4-dioxane medium at various temperature 303 K–288 K and frequency regime (10 MHz–30 GHz) determined from the complex dielectric permittivity spectra obtained by Time Domain Reflectometry(TDR). In this frequency range, the dielectric study gives the electrostatic interaction as well as orientational polarizability of complex mixtures of long chain molecules significantly. Dielectric parameters were calculated from the complex spectra of the binary mixture by non linear least square fit method. The excess permittivity (εE), correlation factors were calculated for the binary system. Thermal parameters(ΔH-enthalpy, ΔS-entropy and ΔG-Gibbs free energy) were calculated and the direction of reaction is determined. The FTIR spectrum of the binary system recorded and the assignments are discussed. The FTIR spectral assignments confirm the molecular interactions.

Sodium-ion hybrid electrolyte battery for sustainable energy storage applications

Senthilkumar, S.T.,Abirami, Mari,Kim, Junsoo,Go, Wooseok,Hwang, Soo Min,Kim, Youngsik Elsevier 2017 Journal of Power Sources Vol.341 No.-

<P><B>Abstract</B></P> <P>Sustainable, safe, and low-cost energy storage systems are essential for large-scale electrical energy storage. Herein, we report a sodium (Na)-ion hybrid electrolyte battery with a replaceable cathode system, which is separated from the Na metal anode by a Na superionic conducting ceramic. By using a fast Na-ion-intercalating nickel hexacyanoferrate (NiHCF) cathode along with an eco-friendly seawater catholyte, we demonstrate good cycling performance with an average discharge voltage of 3.4 V and capacity retention >80% over 100 cycles and >60% over 200 cycle. Remarkably, such high capacity retention is observed for both the initial as well as replaced cathodes. Moreover, a Na-metal-free hybrid electrolyte battery containing hard carbon as the anode exhibits an energy density of ∼146 Wh kg<SUP>−1</SUP> at a current density of 10 mA g<SUP>−1</SUP>, which is comparable to that of lead-acid batteries and much higher than that of conventional aqueous Na-ion batteries. These results pave the way for further advances in sustainable energy storage technology.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel sodium-ion hybrid electrolyte battery is fabricated. </LI> <LI> Nickel hexacyanoferrate is prepared via a precipitation method for the cathode. </LI> <LI> Cathode part is an open system which enables a cathode replaceable. </LI> <LI> Seawater used as a low cost and eco-friendly catholyte. </LI> <LI> Both fresh and replaced cathode exhibit excellent electrochemical performances. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Performance characteristics of p-i-n hetero-junction organic photovoltaic cell with CuPc:F₄-TCNQ hole transport layer

Senthilkumar, N.,Park, S.,Kang, H.S.,Park, D.W.,Choe, Y. Korean Society of Industrial and Engineering Chemi 2011 Journal of industrial and engineering chemistry Vol.17 No.4

We have investigated the effect of strong p-type organic semiconductor F<SUB>4</SUB>-TCNQ-doped CuPc hole transport layer on the performance of p-i-n hetero-junction photovoltaic device from ITO/PEDOT:PSS/CuPc:F<SUB>4</SUB>-TCNQ (5wt%)/CuPc:C60 (blending ratio 1:1)/C60/BCP/LiF/Al, fabricated via vacuum deposition process and have evaluated the J-V characteristics such as short circuit current (J<SUB>sc</SUB>), open circuit voltage (V<SUB>oc</SUB>), fill factor (FF) and energy conversion efficiency (η<SUB>e</SUB>) of the device. By doping of F<SUB>4</SUB>-TCNQ into CuPc hole transport layer, absorption intensities in absorption spectra were increased, which supports that uniform dispersion of organic molecules in the hole transport layer with lowered value of surface roughness can be obtained. Eventually, current injection was enhanced through the layer, which comparatively improves the performance of the photovoltaic cell with energy conversion efficiency of 0.50% in this study.

Graphene oxide self-assembled with a cationic fullerene for high performance pseudo-capacitors

Senthilkumar, Krishnan,Prabakar, S. J. Richard,Park, Chunkuk,Jeong, Seok,Lah, Myoung Soo,Pyo, Myoungho The Royal Society of Chemistry 2016 Journal of Materials Chemistry A Vol.4 No.5

<▼1><P>Control of the microstructures of graphene oxide is realized by introducing a cationic fullerene, resulting in a high-performance pseudo-capacitor.</P></▼1><▼2><P>Control of the microstructures of graphene oxide (GO) is realized by introducing a cationic fullerene (CFU), resulting in a high-performance pseudo-capacitor. The strong electrostatic interaction between anionic GO and the CFU produces a self-assembled composite (GO/CFU), in which the CFU units intervene to form randomly stacked GO layers. The CFU acts as a spacer between GO layers, allowing a significant fraction of the oxygen-functional groups of GO to be redox-active. When tested as a pseudo-capacitor in 1.0 M H2SO4, the optimized GO/CFU composite delivers a capacitance of 357 F g<SUP>−1</SUP> at 0.4 A g<SUP>−1</SUP>, in contrast to 160 F g<SUP>−1</SUP> for GO alone, which is one of the greatest values reported for graphene composites with electro-inactive carbonaceous entities. The improvement in the capacitance by CFU incorporation is also evidenced at a high charge/discharge rate (285 and 137 F g<SUP>−1</SUP> at 5 A g<SUP>−1</SUP> for GO/CFU and GO, respectively). As a result, the GO/CFU composite delivers an energy density of 40 W h kg<SUP>−1</SUP> and a power density of 2793 W kg<SUP>−1</SUP> at 5 A g<SUP>−1</SUP>, in contrast to 19 W h kg<SUP>−1</SUP> and 2748 W kg<SUP>−1</SUP> for GO alone. During 5000 charge/discharge cycles at 5 A g<SUP>−1</SUP>, the capacitance of the GO/CFU composite increases slightly (4% increase in GO/CFU <I>vs.</I> 4% decrease in GO), which validates the effectiveness of a self-assembly strategy for high performance supercapacitor applications.</P></▼2>

Experimental investigation and optimization of machining parameters during machining of glass fibre reinforced epoxy based composite using desirability function analysis

Senthilkumar K.M,Kathiravan N,Girisha L,Sivaperumal M 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.4

In the recent years, mankind has established that the protection of the environment becomes a vital part in the discovery ofany engineering applications. Several engineering applications in the areas of agriculture, forestry, energy industries, havedeveloped several composite materials in place of other materials for its effectiveness. This work focuses on synthesis of acomposite material and the matrix material used in the research work was epoxy resin. Glass fibres were used as thereinforcement material for the preparation of the hybrid epoxy based composite. The epoxy used in this work is LB011 epoxyresin lapox B_11. The hardener used is Triethylenetetraamine (TETA). The composite laminates are prepared by varying theweight proportion of the glass fibres and tested for its mechanical properties. The composite laminate with high tensile strengthis selected for the investigation of machining properties of the composite laminate. Optimization of machining parameter arecarried out by a novel analysis called Desirability Function Analysis (DFA), which is an optimal tool considered for theproblems with multi objective optimization function.