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.

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.

Highly porous graphitic carbon and Ni₂P₂O₇ for a high performance aqueous hybrid supercapacitor

Senthilkumar, Baskar,Khan, Ziyauddin,Park, Seungyoung,Kim, Kyoungho,Ko, Hyunhyub,Kim, Youngsik The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.43

<▼1><P>A high energy hybrid capacitor fabricated from highly porous graphitic carbon and novel electrode material Ni2P2O7 delivers a maximum energy density of 65 W h kg<SUP>−1</SUP> at a power density of 800 W kg<SUP>−1</SUP>, good rate capability and cycling stability in an aqueous Na-ion based electrolyte.</P></▼1><▼2><P>An aqueous Na-ion based hybrid capacitor has been successfully developed by using highly porous graphitic carbon (HPGC) derived from waste writing paper and a new electrode material as a negative and positive electrode, respectively. HPGC was prepared <I>via</I> hydrothermal carbonization and subsequent KOH activation of waste writing paper which showed a highly porous stacked sheet-like morphology with an exceptionally high BET specific surface area (1254 m<SUP>2</SUP> g<SUP>−1</SUP>). HPGC exhibited typical electrical double layer capacitor (EDLC) behavior with a high specific capacitance of 384 F g<SUP>−1</SUP> and good negative working potential (−1.0 V) in an aqueous electrolyte. On the other hand, Ni2P2O7 was synthesized by a simple co-precipitation technique and tested as a cathode material which delivered a maximum specific capacitance of 1893 F g<SUP>−1</SUP> at 2 A g<SUP>−1</SUP> current density. The fabricated HPGC‖Ni2P2O7 hybrid device displayed excellent cyclic stability up to 2000 cycles and delivered a maximum energy density of 65 W h kg<SUP>−1</SUP> at 800 W kg<SUP>−1</SUP> power density in a Na-ion based aqueous electrolyte.</P></▼2>

Flexible Electrospun PVdF-HFP/Ni/Co Membranes for Efficient and Highly Selective Enzyme Free Glucose Detection

Senthilkumar, Nangan,Babu, Kaliyamoorthy Justice,Gnana kumar, Georgepeter,Kim, Ae Rhan,Yoo, Dong Jin American Chemical Society 2014 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.53 No.25

<P>Highly selective and efficient nonenzymatic electrochemical glucose sensors were fabricated by using electrospun polyvinylidenefluoride-<I>co</I>-hexafluoropropylene (PVdF-HFP) composite nanofiber membranes. The homogeneous, smooth and strongly interconnected nanofibers were identified for the bare PVdF-HFP membrane and beads in the PVdF-HFP nanofibers were observed for the PVdF-HFP/Ni and PVdF-HFP/Ni/Co nanofiber membranes. The face-centered cubic structure of Ni nanoparticles doped in the PVdF-HFP nanofibers has not been altered, even after the alloy formation with Co. The electrochemical oxidation of glucose in an alkaline medium was chosen as a probe for the detection of glucose and was achieved through the fabricated nanofiber membranes. Among the fabricated nanofiber membranes, the PVdF-HFP/Ni/Co membrane exhibited an excellent sensing behavior toward glucose with the low limit of detection and linear range of 0.26 μM and 1 μM to 7 mM, respectively. Furthermore, the fabricated nanofiber membrane exhibited good selectivity, high stability and reproducibility, which promises its applications in nonenzymatic glucose sensors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/iecred/2014/iecred.2014.53.issue-25/ie500755m/production/images/medium/ie-2014-00755m_0016.gif'></P>

Direct vapor phase growth process and robust photoluminescence properties of large area MoS2 layers

Senthilkumar, V.,Tam, L. C.,Kim, Y. S.,Sim, Y.,Seong, M. J.,Jang, J. I. Springer Science + Business Media 2014 NANO RESEARCH Vol.7 No.12

만성 및 급성 염증 모델에서 강황추출물의 효과

Senthilkumar Anandakumar,Joshua Allan Joseph,Bharathi Bethapudi,Amit Agarwal,정은봉(Eun-Bong Jung) 한국식품영양과학회 2014 한국식품영양과학회지 Vol.43 No.4

본 연구에서는 강황 유래의 curcuminoids가 없는 다당체를 이용하여 급성 및 만성 염증 모델에서의 항염증 효과를 검증하고자 하였다. 급성염증에 대한 효과를 알아보기 위하여 carrageenan에 의한 족부종 유발과 xylene에 의한 귀부종 유발을 일으킨 모델을 이용하여 수행하였다. Carrageenan 에 의한 족부종 유발 실험에서 강황추출물과 관절염 치료제로 알려진 diclofenac sodium을 처리하였을 때는 부종의 증가도가 낮은 것으로 나타났다(P≤0.05). 또한 다른 급성염증 모델인 xylene application 마우스 모델에서도 대조군에 비하여 diclofenac sodium과 강황추출물(31.5, 63, 126 mg/kg)을 농도별로 경구투여 하였을 때 염증 억제율이 각각 78.13%, 68.75%, 62.50% 및 59.38%로 나타나 염증 억제율이 높은 것으로 나타났다(P≤0.05). 만성염증에 대한 효과를 알아보기 위한 cotton pellet 육아종 실험에서는 대조군과 비교하여 삼출물과 염증 육아종이 적게 발생된 것으로 나타났다(P≤0.05). 따라서 강황 유래의 다당체를 경구투여하였을 때 만성 및 급성 염증에 대한 저해활성이 있는 것으로 나타나 항염증 소재로서 개발 가능성이 있음을 제시하였다. Anti-inflammatory effects of turmeric (Curcuma longa L.) rich in polysaccharides, as well as free of curcuminoids and turmerones were investigated in acute and chronic inflammatory models. Activity against the acute phase of inflammation was evaluated in carrageenan-induced paw edema and xylene-induced ear edema models. The results showed that turmeric extract significantly decreased paw edema volume in the first and third hours after carrageenan injection (P≤0.05). Turmeric extract at all dose levels also significantly inhibited xylene-induced ear edema formation (P≤0.05). Activity against chronic inflammation was also evaluated in cotton pellet-induced granuloma model. Turmeric extract significantly (P≤0.05) decreased the weight of granuloma tissue on cotton pellets in a dose-dependent manner when compared to the vehicle control. Thus, the findings of the study suggest that turmeric extract in effective against both acute and chronic inflammation.

An Level Set Evolution Morphology Based Segmentation of Lung Nodules and False Nodule Elimination by 3D Centroid Shift and Frequency Domain DC Constant Analysis

Senthilkumar Krishnamurthy,Ganesh Narasimhan,Umamaheswari Rengasamy 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.10

A Level Set Evolution with Morphology (LSEM) based segmentation algorithm is proposed in this work to segment all the possible lung nodules from a series of CT scan images. All the segmented nodule candidates were not cancerous in nature. Initially the vessels and calcifications were also segmented as nodule candidates. The structural feature analysis was carried out to remove the vessels. The nodules with more centroid shift in the consecutive slices were eliminated since malignant nodule’s resultant position did not usually deviate. The calcifications were eliminated by frequency domain analysis. DC constant of nodule candidates were computed in frequency domain. The nodule candidates with high DC constant value could be the calcifications as the calcification patterns were homogeneous in nature. This algorithm was applied on a database of 40 patient cases with 58 malignant nodules. The algorithms proposed in this paper precisely detected 55 malignant nodules and failed to detect 3 with a sensitivity of 95%. Further, this algorithm correctly eliminated 778 tissue clusters that were initially segmented as nodules, however, 79 non-malignant tissue clusters were detected as malignant nodules. Therefore, the false positive of this algorithm was 1.98 per patient.

A comprehensive assessment on performance behavior of a CI engine using bio oil emulsions (PJSO10, KSO10 and CSO10) as fuels

Senthilkumar Masimalai,Venkatesan Kuppusamy 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

This paper aims at evaluating the performance of bio oils obtained from pyrolysis of three different biomass (namely Prosopis Julifloraseeds-PJS, Coconut shell-CS and Kiker seeds-KS) as fuels in a compression ignition engine. A single cylinder diesel engine developing apower output of 3.7 kW at 1500 rpm was used. A comparative study was made on the engine’s performance, emission and combustionbehavior of three bio oils by converting them into their emulsions. Bio oil emulsions (namely PJSO10-Prosopis Juliflora emulsion,CSO10-Coconut shell emulsion and KSO10-Kiker seed emulsion) were prepared by mixing 10% of bio oils in the presence of 3% of asurfactant (span 80) with 87% of diesel by volume. Emulsions were tested in a single cylinder diesel engine for their performance as fuel. Engine test results showed comparable performance with all the emulsions of bio oil as compared to BD (Base diesel). CSO10 indicatedthe brake thermal efficiency very close to BD at all power outputs among the tested emulsions. Considerable reduction in smoke andNOx emissions were observed with all the emulsions of bio oil as compared to BD at all power outputs. Cylinder peak pressure andmaximum rate of pressure rise indicated close values to BD at all power outputs with all the emulsions. Ignition delay was found ashigher with all the tested emulsions as compared to BD at all power outputs. From the experimental findings it was concluded that biooils obtained from Prosopis Juliflora seeds-PJS, Coconut shell-CS and Kiker seeds-KS can be used upto 10% by volume (without anymodifications in the engine) as partial replacement of diesel by making emulsions with diesel with comparable performance and considerablereduction in smoke and NOx emissions. Among the emulsions the best choice can be CSO10 for better thermal efficiency andreduced emissions.

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.