Influence of SF₆/N₂ Gas Mixture Ratios on the Lightning Streamer Propagation Characteristics of 22 kV MV Circuit Breaker

Gandhi, R.,Chandrasekar, S.,Nagarajan, C. The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

In recent times, gas insulated medium voltage (MV) circuit breakers (CB) form a vital component in power system network, considering its advantages such as reduced size and safety margins. Gas insulation characteristics of circuit breakers are generally measured by lightning impulse (LI) test according to IEC standard 60060-1 as a factory routine test. Considering the environmental issues of $SF_6$ gas, many research works are being carried out towards the mixture of $SF_6$ gases for high voltage insulation applications. However, few reports are only available regarding the LI withstand and streamer propagation characteristics (at both positive and negative polarity of waveform) of $SF_6/N_2$ gas mixture insulated medium voltage circuit breakers. In this paper, positive and negative polarity LI tests are carried out on 22 kV medium voltage circuit breaker filled with $SF_6/N_2$ gas mixture at different gas pressures (1-5 bar) and at different gas mixture ratios. Important LI parameters such as breakdown voltage, streamer velocity, time to breakdown and acceleration voltage are evaluated with IEC standard LI ($1.2/50{\mu}s$) waveform. Weibull distribution analysis of LI breakdown voltage data is carried out and 50% probability breakdown voltage, scale parameter and shape parameter are evaluated. Results illustrate that the $25%SF_6+75%N_2$ gas filled insulation considerably enhances the LI withstand and breakdown strength of MV circuit breakers. LI breakdown voltage of circuit breaker under negative polarity shows higher value when compared with positive polarity. Results show that maintaining the gas pressure at 0.3 MPa (3 bar) with 10% $SF_6$ gas mixed with 90% $N_2$ will give optimum lighting impulse withstand performance of 22 kV MV circuit breaker.

Development and characterization of microemulsion based topical gel of essential oil of clove (Syzygium aromaticum) for superficial fungal infections

Gandhi Jeet,Suthar Disha,Patel Hetal,Shelat Pragna,Parejiya Punit 경희대학교 융합한의과학연구소 2021 Oriental Pharmacy and Experimental Medicine Vol.21 No.3

A widespread of superficial fungal infections deals with concerns related to current therapeutic regimen such as drug resistance and adverse events associated with the same which leads exploration of natural oils as an antifungal agent. The aim of present work is to the development of clove oil loaded microemulsion based gel for treatment of superficial fungal infections. The microemulsion based gel was prepared by phase titration method and optimized using D-optimal design considering globule size, drug permeation and drug retention on skin as critical quality attributes. The MIC and zone of inhibition of clove oil was found to be 2.2 mg/ml and 38 mm respectively. A pale to yellowish transparent microemulsion had a globule size, zeta-potential and PDI of 14.41 nm, 0.73 and 0.0113 respectively indicating a stable microemulsion. A clove oil loaded microemulsion based gel (CLMBG) with a pH of 6.27 and viscosity of 12.87 m.pas/sec exhibited a comparable texture profile to marketed preparation. The drug release of the CLMBG with a drug content of 102.6 ± 4% in acetate buffer pH 5.5 was 98.5 ± 0.35% ensuring complete drug release from the formulation. Ex-vivo drug permeation study and skin irritation study dictated the retention of drug at site of action and the formulation to be non-irritant. The antifungal study proved the formulation to have similar efficacy as the marketed product (clobet gel). The stability study indicated the product to be safe, efficacious and stable formulation. From the above results, it can be derived that clove oil loaded microemulsion based gel can be a promising alternative to current antifungal regimens.

Robustness of Selection Indices in Murrah Buffaloes

Gandhi, R.S.,Joshi, B.K. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.2

Data pertaining to first lactation records of 316 Murrah buffaloes, progeny of 47 sires, maintained at NDRI Farm for a period of 18 years were analysed to construct selection indices and to examine their robustness by changing the relative economic values of different economic traits. A total of 120 selection indices were constructed for three sets of relative economic values ( 40 for each set) considering different combinations of seven first lactation traits viz. age at first calving (AFC), first lactation 305 day or less milk yield (FLMY), first lactation length (FLL), first calving interval (FCI), milk yield per day of first lactation length (MY/FLL), milk yield per day of first calving interval (MY/FCI) and milk yield per day age at second calving (MY/ASC). The three sets of relative economic values were based on economic values of different traits, 1% standard deviation of different traits and regression of different traits on FLMY. The 'optimum' indices for the first two sets had five traits each namely AFC, FLMY, FLL, FCI and MY/ASC giving improvement in aggregate genotype of Rupees 269.11 and Rs. 174.88, respectively. The accuracy of selection from both indices was 70.79 and 69.39%, respectively. The 'best' selection index from the third set of data again had five traits (AFC, FLMY, FLL, FCI and MY/FLL) giving genetic gain of Rs. 124.16 and accuracy of selection of 71.81%. The critcal levels or break-even points for FLMY for varying levels of AFC and FCI estimated from the "optimum index" suggested the need of enhancement of present production level of the herd or reduction of AFC or FCI. It was concluded that economic values of various first lactation traits were the most appropriate to construct selection indices as compared to other criteria of assigning relative economic weights in Murrah buffaloes.

Analysis of material dependency in an elastic - plastic contact models using contact mechanics approach

Gandhi, V.C. Sathish,Kumaravelan, R.,Ramesh, S.,Sriram, K. Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.5

The study aims on the effect of material dependency in elastic- plastic contact models by contact analysis of sphere and flat contact model and wheel rail contact model by considering the material properties without friction. The various materials are selected for the analysis based on Young's modulus and yield strength ratio (E/Y). The simulation software 'ANSYS' is employed for this study. The sphere and flat contact model is considered as a flattening model, the stress and strain for different materials are estimated. The simulation of wheel-rail contact model is also performed and the results are compared with the flattening model. The comparative study has also been extended for finding out the mean contact pressure for different materials the E/Y values between 150 and 660. The results show that the elastic-plastic contact analysis for materials up to E/Y=296.6 is depend on the nature of material properties and also for this material the mean contact pressure to yield strength reaches 2.65.

Effect of packing materials on the decomposition of tetrafluoroethane in a packed-bed dielectric barrier discharge plasma reactor

Gandhi, M. S.,Mok, Y. S. Springer-Verlag 2015 International journal of environmental science and Vol.12 No.2

Effect of curcumin in the prevention of experimentally induced nephrolithiasis in rats by ethylene glycol and Vitamin D3

Gandhi, Chintan N,Balaraman, R Kyung Hee Oriental Medicine Research Center 2009 Oriental pharmacy and experimental medicine Vol.9 No.3

Curcumin (CMN) is known to have beneficial role in anorexia, coryza, cough, diabetic wounds, and hepatic disorders apart from its inherent antioxidant effects. Therefore, the present study was aimed to evaluate antioxidant effect of CMN in prevention of nephrolithiasis in rats-induced by ethylene glycol (EG) and Vitamin D3 (Vit. D3). Male Wistar rats (175 - 200 g) were randomized in groups like control, EG + Vit. D3 induced nephrolithiatiatic rats, CMN treated rats, CMN + EG + Vit. D3 treated rats, Vit. E + EG + Vit. D3 treated rats. Urine was collected weekly throughout the experimental protocol and estimated for calcium oxalate (CaO) count. After completion of experimental protocol serum was estimated for blood urea nitrogen and creatinine. Both the kidneys were excised and used to evaluate levels of biomarkers of oxidative stress and calcium oxalate crystal deposition by histopathological studies. Administration of EG and Vit. D3 to rats resulted in increased oxidative stress, hyperoxaluria and renal deposition of CaO crystals. Supplementation with CMN improves kidney function, reduces elevated oxidative stress, urinary oxalate level and renal deposition of CaO which shows its protective action in nephrolithiasis. The increased deposition of stone in the kidney and stone forming constituents of nephrolithiatic rats were effectively lowered by treatment of CMN.

Hesperidin improves warm ischemia/reperfusion-induced oxidative renal injury in rats

Gandhi, Chintan,Zalawadia, Rishit,Balaraman, R. Kyung Hee Oriental Medicine Research Center 2009 Oriental pharmacy and experimental medicine Vol.9 No.4

Ischemia/reperfusion injury, which is commonly seen in the field of renal surgery or transplantation, is a major cause of acute renal failure. Previous studies showed that antioxidant treatments attenuated renal ischemia/reperfusion injury. The objective of this study was to examine the role of hesperidin in modulating reactive oxygen species induced inflammation and apoptosis after renal ischemia/reperfusion injury. Rats were subjected to right nephrectomy, 15 days later 45 min of renal ischemia and 24 h reperfusion with or without treatment with hesperidin. Renal function, inflammation and apoptosis were compared at 24 h after reperfusion injury. Hesperidin improved the renal dysfunction and reduced inflammation and apoptosis after ischemia/reperfusion injury. In conclusion, hesperidin shows potent anti-apoptotic and antiinflammatory properties due to antioxidant property. These findings may have major implications in the treatment of human ischemic acute renal failure.

Synthesis of a novel hierarchical mesoporous organic–inorganic nanohybrid using polyhedral oligomericsilsesquioxane bricks

Gandhi, Sakthivel,Kumar, Prem,Thandavan, Kavitha,Jang, Kiwan,Shin, Dong-Soo,Vinu, Ajayan The Royal Society of Chemistry 2014 NEW JOURNAL OF CHEMISTRY Vol.38 No.7

<P>A successful method has been demonstrated for the synthesis of a mesoporous organic–inorganic nanohybrid using amine functionalized polyhedral oligomericsilsesquioxane (POSS) and pluronic polymer as a silica precursor and structure directing agent, respectively. The results confirmed the presence of porous structure, along with the high surface area and uniform pore size distribution which can be utilized for various applications namely catalysis, drug-delivery, <I>etc.</I></P> <P>Graphic Abstract</P><P>A novel mesoporous silica with high surface area and ordered porosity has been developed using <I>N</I>-methylamino POSS and dichloromethylsilane. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4nj00292j'> </P>

Laboratory Evaluation of Relative Toxicities of Some Insecticides Against Trichogramma chilonis (Hymenoptera: Trichogrammatidae) and Chrysoperla carnea (Neuroptera: Chrysopidae)

Gandhi Pandiyan Indira,Gunasekaran Kulaiyappa,Poonguzhali Selvaraj,Anandham Rangasamy,Kim Gil-Hah,Chung Keun-Yook,Sa Tong-Min Korean Society of Applied Entomology 2005 Journal of Asia-Pacific Entomology Vol.8 No.4

Laboratory experiment was conducted to compare the relative toxicity of biopesticides like Pseudomonas fluorescens strain pf1 and neem oil with imidacloprid, quinalphos, and endosulfan against an egg parasitoid, Trichogramma chilonis, and a predatory green lacewing, Chrysoperla carnea. Biopesticides were safer than chemical insecticides in minimizing harmful effects on development and behavior of two natural enemies. P. fluorescens treatment recorded high parasitism (${\thickapprox}73%$) and parasitoid egg development (${\thickapprox}72%$) of T. chilonis. It also gave high egg (${\thickapprox}75%$) development on C. carnea. Neem oil recorded 58.9 % parasitoid emecrgence, and 59.3 % parasitism, and 63.1 % egg hathability. Other chemical insecticides exhibited high damages on the natural enemies.

First Order Differential Subordinations for Carathéodory Functions

Gandhi, Shweta,Kumar, Sushil,Ravichandran, V. Department of Mathematics 2018 Kyungpook mathematical journal Vol.58 No.2

The well-known theory of differential subordination developed by Miller and Mocanu is applied to obtain several inclusions between $Carath{\acute{e}}odory$ functions and starlike functions. These inclusions provide sufficient conditions for normalized analytic functions to belong to certain class of Ma-Minda starlike functions.