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.

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

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>

Push out tests on various shear connectors used for cold-formed steel composite beam

Senthilkumar Rajendran,Jayabalan Perumalsamy,Divya Mohanraj 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.3

Shear connectors are key elements that ensure integrity in a composite system. The primary purpose of a shear connector is to bring a high degree of interaction between composite elements. A wide variety of connectors are available for hot-rolled composite construction, connected to the beam through welding. However, with cold-formed members being very thin, welding of shear connectors is not desirable in cold-formed composite constructions. Shear connectors for cold-formed elements are limited in studies as well as in the market. Hence in this study, three different types of shear connectors, namely, single-channel, double channel, and self–tapping screw, were considered, and their performance assessed by the Push-out test as per Eurocode 4. The connection between channel shear connectors and the beam was made using self-tapping screws to avoid welding. The performance of the connectors was analyzed based on their ultimate capacity, characteristic capacity, ductility, and slippage during loading. Strength to weight ratio was also carried out to understand the proposed connectors' suitability for conventional ones. The results showed relatively higher initial stiffness and ductility for double channel connectors than other connectors. Also, self-tapping screws had a higher strength to weight ratio with low ductility.

NUMERICAL SOLUTION FOR ROBOT ARM PROBLEM USING LIMITING FORMULAS OF RK(7,8)

Senthilkumar, S. Korean Society of Computational and Applied Mathem 2008 Journal of applied mathematics & informatics Vol.26 No.3-4

The aim of this article is focused on providing numerical solutions for system of second order robot arm problem using the RK-eight stage seventh order limiting formulas. The parameters governing the arm model of a robot control problem have also been discussed through RK-eight stage seventh order limiting algorithm. The precised solution of the system of equations representing the arm model of a robot has been compared with the corresponding approximate solutions at different time intervals. Results and comparison show the efficiency of the numerical integration algorithm based on the absolute error between the exact and approximate solutions. Based on the numerical results a thorough comparison is carried out between the numerical algorithms.

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.

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.

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.

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.