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.

Potentiostatic activation of as-made graphene electrodes for high-rate performance in supercapacitors

Senthilkumar, K.,Jeong, S.,Lah, M.S.,Sohn, K.S.,Pyo, M. Elsevier Sequoia 2016 Journal of Power Sources Vol. No.

A thermally expanded graphene oxide (EGO) electrode is electrochemically activated to simultaneously introduce electrolyte-accessible mesopores and oxygen functional groups. The former is produced via O<SUB>2</SUB> evolution and the latter is incorporated by the intermediate hydroxyl radicals generated during the potentiostatic oxidation of H<SUB>2</SUB>O in 1 M H<SUB>2</SUB>SO<SUB>4</SUB> at 1.2 V (vs. Ag/AgCl). When applied as a supercapacitor, the potentiostatically treated EGO (EGO-PS) shows significant enhancement in an electric-double layer (EDL) process with a noticeable Faradaic reaction and delivers high capacitance at fast charge/discharge (C/D) rates (334 F g<SUP>-1</SUP> at 0.1 A g<SUP>-1</SUP> and 230 F g<SUP>-1</SUP> at 50 A g<SUP>-1</SUP>). In contrast to EGO-PS, EGO that is oxidized potentiodynamically (EGO-PD) shows negligible enhancement in EDL currents. EGO that is subjected to successive potential pulses also shows behaviors similar to EGO-PD, which indicates the importance of hydroxyl radical accumulation via a potentiostatic method for simultaneous functionalization and microstructural control of graphenes. The potentiostatic post-treatment presented here is a convenient post-treatment strategy that could be used to readily increase capacitance and simultaneously improve the high-rate performance of carbon-based electrodes.

Machining of CFRP/Ti6Al4V stacks under minimal quantity lubricating condition

Senthilkumar M.,Prabukarthi A.,Krishnaraj V. 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.8

Light weight and high strength materials like carbon fiber reinforce plastics (CFRP), Titanium alloys (Ti) and stacks (CFRP/Ti, CFRP/Al, CFRP/Al/Ti) are being extensively used in commercial aircraft. Drilling process on the aircraft components was carried out to facilitate the assembly process. Drilling operations are made under dry condition which leads to tool wear and poor hole quality. In this paper study on drilling of CFRP/Ti6Al4V stacks under minimum quantity lubrication (MQL) using LRT 30 oil with varying flow rate, spindle speed and feed rate have been carried out using three modified drill tool made of solid carbide (K 20) coated with TiAlN. The recital of the tools were evaluated based on hole quality, burr height, thrust force, chip formation and tool wear. It was found that TG1 tool performance was better by producing minimum burr height while drilling Ti. TG2 recital was better by producing minimum force and better hole quality.

Impact of Tobacco on Glutathione S Transferase Gene Loci of Indian Ethnics

Senthilkumar, K.P.,Thirumurugan, Ramasamy Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10

Background: Tobacco contains agents which generate various potent DNA adducts that can cause gene mutations. Production of DNA adducts may be neutralized by glutathione S transferase (GST) along with other phase I and phase II enzyme systems. The existence of null type of GST among the population increases the susceptibility to various disorders and diseases. The present study focuses on the impact of high tobacco usage and possible null type mutation in GST loci. Methods: Genotypes of GST were detected by multiplex polymerase chain reaction in unrelated 504 volunteers of high tobacco using natives of Gujarat. Allelic frequencies were calculated using Statistical Package for Social Studies-16 software. Hardy Weinberg Equilibrium (HWE) was calculated using Chi square test. Two sided Fisher's significance test was used to compare allelic frequencies of different populations. Results: The frequency of homozygous null genotype of GSTM1 and GSTT1 were 20% (95% CI 16.7-23.9) and 35.5% (95% CI 31.4-39.9) respectively. The GSTM1 and GSTT1 null allele frequency distribution in the Gujarat population was significantly deviating from HWE. GSTT1 null frequency of Gujaratians was significantly higher and different to all reported low tobacco using Indian ethnics, while GSTM1 was not differing significantly. Conclusion: Tobacco usage significantly influences the rate of mutation and frequency of GSTT1 and M1 null types among the habituates. The rate of mutation in GSTT1 loci was an undeviating response to the dose of tobacco usage among the population. This mutational impact of tobacco on GSTT1 postulates the possible gene - environment interaction and selection of null genotype among the subjects to prone them under susceptible status for various cancers and even worst to cure the population with GSTT1 dependent drugs.

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.

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.

Progressive muscle relaxation technique on anxiety and depression among persons affected by leprosy

Senthilkumar Ramasamy,Suganya Panneerselvam,Pitchaimani Govindharaj,Archana Kumar,Rashmi Nayak 한국운동재활학회 2018 JER Vol.14 No.3

Bhopal Methyl Isocyanate Affected Population and Cancer Susceptibility: Where Do We Stand Now?

Senthilkumar, Chinnu Sugavanam Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 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.