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.

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

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.

GSTM1 and GSTT1 Allele Frequencies among Various Indian and non-Indian Ethnic Groups

Senthilkumar, K.P.,Thirumurugan, R. Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12

Background: Glutathione-S-transferase (GST) is an important phase II xenobiotic compound metabolizing enzyme family, involved in tolerance to a particular drug or susceptibility to a diseasec. This study focused the GSTM1 and T1 null allele frequency in the Gujarat population with a comparison across other Inter- and Intra-Indian ethnic groups to predict variation in the possible susceptible status. Methods: DNA was isolated by a salting out method and GSTM1 and T1 homozygous null genotypes were detected by multiplex polymerase chain reaction in 504 unrelated individuals. The genotype distribution of null alleles was compared with Indian and non Indian ethnics reported earlier in the literature using Fisher's test. Results: The frequencies of the homozygous null genotypes of GSTM1 and GSTT1 were 20% (95%CI 16.7-23.9) and 35.5% (95%CI 31.4-39.9) respectively. GSTM1 null frequency did not deviate from most other Indian ethnic groups but differed from the majority of those of non Indian ethnicity studied. The frequency of homozygous null type of GSTT1 was significantly higher and deviated from all Indian groups and a few of non Indian ethnicity. Conclusions: Gujarat ethnicity, possibly the most susceptible for GSTT1 dependent drug disposition and diseases regarding effects of pollution. Further, the results have implications for GSTT1 dependent drugs used for treatment, a serious problem which needs to be solved by physicians and clinical researchers.

Enterourachal Fistula as an Initial Presentation in Crohn Disease

Senthilkumar Sankararaman,Ramy Sabe,Thomas J. Sferra,Ali Salar Khalili 대한소아소화기영양학회 2019 Pediatric gastroenterology, hepatology & nutrition Vol.22 No.1

Crohn disease has a wide spectrum of clinical presentations and rarely can present with complications such as a bowel stricture or fistula. In this case report, we describe a 17-year-old male who presented with a history of recurrent anterior abdominal wall abscesses and dysuria. He was diagnosed with Crohn disease and also found to have a fistulous communication between the terminal ileum and a patent urachus. An ileocecectomy with primary anastomosis and complete resection of the abscess cavity was performed. He is on azathioprine for maintenance therapy and currently in remission. Clinicians should have a high index of suspicion for this complication in Crohn disease patients presenting with symptoms suggestive of urachal anomalies such as suprapubic abdominal pain, dysuria, umbilical discharge, and periumbilical mass.

Influence of Cryogenic Treatment on TiC nano powder in R600a & R290 Refrigerant used in Vapour Compression Refrigeration System

Senthilkumar D. 대한설비공학회 2019 International Journal of Air-Conditioning and Refr Vol.27 No.4

This paper is to study the performance of vapour compression refrigeration system using, hydrocarbon refrigerant (HCR) mixture (R600a & R290), hydrocarbon nanorefrigerant mixture (R600a & R290/TiC) and cryogenically treated hydrocarbon nanorefrigerant mixture (R600a & R290/ Cryo TiC). The COP of HCR (R600a & R290) system is 1.2960 whereas COP of R600a & R290/TiC nano refrigerant system is 1.5223. The TiC nano powder is cryogenically treated at -196°C for 24 hours. The treated TiC is dispersed in HCR mixture. Hence, the COP of R600a & R290- Cryo TiC system is further increased to 1.5801. The energy consumption of R600a & R290-TiC is reduced by 10.3% when compared with HCR. Further it is reduced by 12.69% with respect to Cryogenically treated refrigerant (R600a & R290/Cryo TiC) system. The COP is enhanced due to deep cryogenic of TiC nano powder .

RK- Methods for Robot Application problems

Senthilkumar, Sukumar,Lee, Malrey,Kwon, Tae-Kyu The Institute of Internet 2013 International journal of advanced smart convergenc Vol.2 No.1

The significance, is to introduce a novel way to employ the improved Runge-Kutta fifth order five stage method, here after called as Modified IRK(5,5) method, for system of second order robot arm problem and variations in angles at the joints in which parameters governing with two degrees of freedom which requires lesser number of function evaluations per time step as compared to the existing ones, in order to save time and spaceAn ultimate aim of this present paper is to solve application problem such as robot arm and initial value problems by applying Runge-Kutta fifth order five stage numerical techniques. The calculated output for robot arm coincides with exact solution which is found to be better, suitable and feasible for solving real time problems.

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.

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.