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Search Results: 1 - 10 of 35 matches for " Chamundeeswari Vinayagam "
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Comparative Analysis of Analog and Digital Controllers for Negative Output Superlift Luo Converter (NOSLC)  [PDF]
Chamundeeswari Vinayagam, Seyezhai Ramalingam
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78146
Abstract: This paper focuses on the comparative study of analog and digital control techniques for Negative Output Superlift Luo converter (NOSLC). NOSLC is a high gain converter in which the positive source voltage is converted into a negative load voltage. Though the negative load voltage is produced effectively, there is lot of non-linearities that affects the voltage level. To overcome this, analog controllers like Proportional-integral (PI), fuzzy PI and a sliding mode controller (SMC) were proposed for NOSLC. However PI controller does not respond to changes in operating point, fuzzy PI is based on the systematic approach and proved to be a trial and error oriented method and SMC brings an oscillation in the duty cycle. Therefore, to overcome these drawbacks, a digital control technique using PIC microcontroller is proposed in this paper which provides high versatility and programmability approach. Simulation studies are carried out in MATLAB and the performances of these controllers have been investigated for the proposed DC-DC converter. A prototype of the NOSLC converter is built by employing digital control and the results are verified experimentally.
An Approach towards Pulse Data Transmission Using Modified Negative Luo Converter (MNLC) for Telecoms  [PDF]
V. Chamundeeswari, Dr. R. Seyezhai
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.79234
Abstract: Telecom sectors generally operate at negative voltages to reduce the effect of corrosion caused in the metallic wire due to electrochemical reaction while communicating signals. To feed those lines and to have an effective digital data transmission, a power electronic converter referred as Modified Negative Luo Converter (MNLC) is proposed in this paper. MNLC is a high gain converter in which the output voltage increases in geometric progression. This paper portrays a novel concept of a 50 Hz pulse data transmission throughRLCG (Resistance-inductance-capacitance with a shunt conductance) transmission line using MNLC. Signal frequency of 50 Hz to be transmitted is anded with a high frequency pulse that charges and discharges MNLC and produces the boosted negative output voltage. The boosted output is again transmitted through the RLCG transmission line from which 50 Hz data pulse is retrieved at the output of the transmission line by comparing with a comparator signal. This sort of MNLC aided data transmission not only introduces less loss in its transmitted data but also overcomes various health hazards of conventional radio frequency (RF) communication. This technique also proves that any data bit stream can be transmitted and retrieved using the proposed high gain DC-DC converter. The simulation model of the proposed system is implemented in MATLAB for various switching frequencies with its prototype of the converter developed and the results are verified.
Image-guided biopsy of mammographic microcalcifications
R Vinayagam, P Gill
Breast Cancer Research , 2006, DOI: 10.1186/bcr1431
Abstract: Retrospective analysis of all stereotactic 14G core biopsies performed in a Breast Screening Unit over an 18-month period (January 2004–June 2005). Usage of department database, mammograms and case notes.Of 300 biopsies, 264 were performed by radiographers. All cases had specimen radiography. The calcium retrieval rate was 80% in early 2004 and 95% by the end of July 2005.The calcifications were classified into cluster, tiny cluster and scattered cluster, according to the mammographic appearances. In the negative biopsies they were 32%, 43% and 25%, respectively.The comparison between the radiologist opinion against the final core biopsy results shows 90% concordance with pathology for opinions 2 and 5, and 75% for opinions 3 and 4.Calcium retrieval rates for radiographers initially matched, then exceeded, those for radiologists. They also showed a steady improvement during the study period, rising to 95%. The cluster morphology did influence the calcium retrieval rate. There was a good concordance of radiology and pathology opinion.
The Adverse Impact of Maternal Obesity on Intrapartum and Perinatal Outcomes
Dimuthu Vinayagam,Edwin Chandraharan
ISRN Obstetrics and Gynecology , 2012, DOI: 10.5402/2012/939762
The Adverse Impact of Maternal Obesity on Intrapartum and Perinatal Outcomes
Dimuthu Vinayagam,Edwin Chandraharan
ISRN Obstetrics and Gynecology , 2012, DOI: 10.5402/2012/939762
Abstract: Background. Confidential enquiries into maternal deaths in the UK have repeatedly highlighted increased maternal morbidity and mortality associated with maternal obesity. Objective. To determine the impact of increased body mass index (BMI) on intrapartum outcomes. Materials and Methods. A retrospective case-control analysis of intrapartum outcomes of the study group (100 women), with a BMI above 40?kg/m2 (class III Obesity) at booking and a control group (100 women) with a booking BMI between 20 and 25?kg/m2 was performed. Results. A statistically significant increase in delivery by caesarean section (OR 2.32, 95% CI 1.26–4.29), minor and major postpartum haemorrhage (OR 5.93, 95% CI 2.34–11.98, OR 16.11, 95% CI 2.08–125.09, resp.), perineal trauma (OR 2.59, 95% CI 1.44–4.69), and fetal macrosomia (OR 3.11, 95% CI 1.25–7.79) was noted in the study group. Babies also had an increased risk of having a lower APGAR scores in the study group as compared to the control group (OR 3.09, 95% CI 1.07–8.94). Conclusion. Women with a BMI > 40?kg/m2 experience increased incidence of intrapartum complications and hence, input of skilled birth attendants during labour is essential to improve intrapartum outcomes. 1. Introduction There has been a staggering rise in the prevalence of obesity, both in the UK as well as worldwide. Obesity is a modern-day epidemic with implications across the whole of the healthcare services, not just maternity services. The worldwide prevalence has doubled in the past 30 years, with approximately 300 million women aged above 20 being classified as overweight [1]. Body Mass Index (BMI) is used as a universal method of classifying obesity. It is a simple index, calculated by dividing an individuals’ weight in kilograms by the square of their height in metres squared. UK prevalence rates for obesity in 2002 for females aged 16–24 and 25–34 was 11.3% and 20.9%, respectively [2]. In 2007, 24% of women aged above 16?yrs were classified as obese [3], indicating a significant rise. In 2010, 43 million children aged under 5 were classified as overweight [1] (BMI above 25) which has implications for the forthcoming generation of mothers. The predominant aetiology of obesity is an imbalance between the amount of calories consumed and amount expended. The sharp rise in the prevalence of obesity is multifactorial, and amongst others, the result of changes in dietary habits, sedentary lifestyles, and urbanisation. The health implications of obesity are severe; there is a clear and well-documented association between obesity and cardiovascular disease,
Power Quality Analysis in Microgrid: An Experimental Approach  [PDF]
Arangarajan Vinayagam, KSV Swarna, Sui Yang Khoo, Alex Stojcevski
Journal of Power and Energy Engineering (JPEE) , 2016, DOI: 10.4236/jpee.2016.44003
Abstract: Microgrid (MG) integrated with Distributed Generation (DG) provides several benefits like reliable, secure, and high efficient of energy supply, while minimizing power loss, deferring expansion of power distribution infrastructures, and reduced carbon emission of energy supply etc. to the communities. Despite of the several benefits, there are several challenges existing due to the integration of different characteristics and technology of DG sources in MG network. Power Quality (PQ) issue is one of the main technical challenges in MG power system. In order to provide improved PQ of energy supply, it is necessary to analyse and quantify the PQ level in MG network. This paper investigates the detail of PQ impacts in a real MG network carried out through an experimental analysis. Voltage and frequency variations/deviations are analysed in both on-grid and off-grid mode of MG operation at varying generation and varying load conditions. Similarly unbalance voltage and current level in neutral are estimated at unbalanced PV generation and uneven load distribution in MG network. Also current and voltage THD are estimated at different PV power level. Finally the results obtained from the analysis are compared to that of Australian network standard level.
Fractal dimensional surface analysis of AISI D2 Tool steel material with nanofluids in grinding process using atomic force microscopy
Prabhu, S.;Vinayagam, B. K.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2011, DOI: 10.1590/S1678-58782011000400009
Abstract: the surface analysis of nanomachined aisi d2 tool steel materials is measured using atomic force microscopy. the surface roughness and fractal dimensional analysis are the important factors in nano tribology and evaluating the quality of nanomachined surface. carbon nanotube increases the heat carrying capacity, thermal conductivity of the lubricating oil and thus prevents any damage to the work piece. the surface morphology of different machined surface was studied by fractal dimension analysis and roughness characterization was carried out. the results indicate that the fractal dimension changed according to the smoothness of the machined surface. the power spectrum density (psd) method based root mean square (rms) surface roughness was calculated for carbon nano tube based nanofluids in grinding process. the fractal dimension and roughness are decreased due to single wall carbon nano tube based nanofluids and smooth surface finish has been obtained.
An Analytical Window into the World of Ultracold Atoms
R. Radha,P. S. Vinayagam
Physics , 2015,
Abstract: We review the recent developments which had taken place in the domain of quasi one dimensional BECs from the viewpoint of integrability. To start with, we consider the dynamics of scalar BECs in a time independent harmonic trap and observe that the scattering length (SL) can be suitably manipulated either to compress the bright solitons to attain peak matter wave density without causing their explosion or to broaden the width of the condensates without diluting them. When the harmonic trap frequency becomes time dependent, we notice that one can stabilize the condensates in the confining domain while the density of the condensates continue to increase in the expulsive region. We also observe that the trap frequency and the temporal SL can be maneuvered to generate matter wave interference patterns indicating the coherent nature of the atoms in the condensates. We also notice that a small repulsive three body interaction when reinforced with attractive binary interaction can extend the region of stability of the condensates in the quasi-one dimensional regime. On the other hand, the investigation of two component BECs in a time dependent harmonic trap suggests that it is possible to switch matter wave energy from one mode to the other confirming the fact that vector BECs are long lived compared to scalar BECs. The Feshbach resonance management of vector BECs indicates that the two component BECs in a time dependent harmonic trap are more stable compared to the condensates in a time independent trap. The introduction of weak time dependent Rabi coupling rapidly compresses the bright solitons which however can be again stabilized through Feshbach resonance or by finetuning the Rabi coupling while the spatial coupling of vector BECs introduces a phase difference between the condensates which subsequently can be exploited to generate interference pattern in the bright or dark solitons.
Effect of hydroalcoholic extract of aerial parts of Leucas aspera (Willd.) link on inflammatory markers in complete freund′s adjuvant induced arthritic rats
Kripa K,Chamundeeswari D,Thanka J,Reddy C
International Journal of Green Pharmacy , 2010,
Abstract: The plant Leucas aspera is claimed to possess anti-inflammatory and anti-rheumatic potential by traditional practitioners. The aim of this study is to validate the traditional claim. The hydroalcoholic extract of aerial parts of L. aspera (HAELA) was orally tested at a dose of 100 mg/kg bodyweight for anti-arthritic effect in adjuvant-induced arthritic rats. Group I rats served as vehicle control group [0.2% carboxyl methyl cellulose (CMC) p.o.]. The test groups were injected with 0.1 ml of complete Freund′s adjuvant into the subplantar region of right hind paw. Group II animals served as disease control, while the group III and group IV arthritic rats were treated with standard drug diclofenac sodium (0.3 mg/kg) and HAELA (100 mg/kg) for 21 days. Activities of inflammatory markers such as tumour necrosis factor-α, C-reactive protein, interleukin-2, cathepsin D and antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were estimated in plasma/haemolysate and tissue of control and arthritic animals. Histopathological analysis of knee joints was also performed. Statistical analysis of the biochemical parameters was performed by one way analysis of variance (ANOVA) using SPSS software package. Results were expressed as mean±SEM for six rats in each group. P<0.05 was considered to be significant. HAELA showed significant anti-inflammatory (P<0.001) and antioxidant activity (P<0.001) at the specified dose. It did not show mortality up to 2000 mg/kg body weight. Histopathological studies confirmed cartilage regeneration and near normal joint in HAELA treated rats. It can thus be concluded that HAELA possesses significant antioxidant and anti-arthritic potential.
Cyclic contractions and fixed points in dislocated metric spaces
R. George,R. Rajagopalan,S. Vinayagam
International Journal of Mathematical Analysis , 2013,
Abstract: Fixed point theorems for various cyclic contractions are provedin dislocated metric space. Our result generalises many well known fixed pointtheorems.
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