Measurement of outgassing rates of Kevlar and S-Glass materials used in torque tubes of High Tc Superconducting (HTS) Motors

S. Thadela,B V A S Muralidhar,B Kalyani,U K Choudhury,S N Yadav,V. V. Rao 한국초전도.저온공학회 2018 한국초전도저온공학회논문지 Vol.20 No.4

Torque tubes in High Temperature Superconducting (HTS) motor transfer torque from superconducting field winding rotor to the room temperature shaft. It should have minimum heat conduction property for minimizing the load on cryo-refrigerator. Generally, these torque tubes are made with stainless steel material because of high strength, very low outgassing and low thermal contraction properties at cryogenic temperatures and vacuum conditions. With recent developments in composite materials, these torque tubes could be made of composites such as Kevlar and S-Glass, which have the required properties like high strength and low thermal conductivity at cryogenic temperatures, but with a reduced weight. Development and testing of torque tubes made of these composites for HTS motor are taken up at Bharat Heavy Electricals Limited (BHEL), Hyderabad in collaboration with Central Institute of Plastics and Engineering Technology (CIPET), Chennai and Indian Institute of Technology (IIT), Kharagpur. As these materials are subjected to vacuum, it is important to measure their outgassing rates under vacuum conditions before manufacturing prototype torque tubes. The present study focusses on the outgassing characteristics of Kevlar and S-Glass, using an Outgassing Measurement System (OMS), developed at IIT Kharagpur. The OMS facility works under vacuum environment, in which the test samples are exposed to vacuum conditions over a sufficient period of time. The outgassing measurements for the composite samples were obtained using pressure-rise technique. These studies are useful to quantify the outgassing rate of composite materials under vacuum conditions and to suggest them for manufacturing composite torque tubes used in HTS motors.

Measurement of outgassing rates of Kevlar and S-Glass materials used in torque tubes of High Tc Superconducting (HTS) Motors

Thadela, S.,Muralidhar, BVAS,Kalyani, B,Choudhury, UK,Yadav, SN,Rao, V.V. The Korean Society of Superconductivity and Cryoge 2018 한국초전도저온공학회논문지 Vol.20 No.4

Torque tubes in High Temperature Superconducting (HTS) motor transfer torque from superconducting field winding rotor to the room temperature shaft. It should have minimum heat conduction property for minimizing the load on cryo-refrigerator. Generally, these torque tubes are made with stainless steel material because of high strength, very low outgassing and low thermal contraction properties at cryogenic temperatures and vacuum conditions. With recent developments in composite materials, these torque tubes could be made of composites such as Kevlar and S-Glass, which have the required properties like high strength and low thermal conductivity at cryogenic temperatures, but with a reduced weight. Development and testing of torque tubes made of these composites for HTS motor are taken up at Bharat Heavy Electricals Limited (BHEL), Hyderabad in collaboration with Central Institute of Plastics and Engineering Technology (CIPET), Chennai and Indian Institute of Technology (IIT), Kharagpur. As these materials are subjected to vacuum, it is important to measure their outgassing rates under vacuum conditions before manufacturing prototype torque tubes. The present study focusses on the outgassing characteristics of Kevlar and S-Glass, using an Outgassing Measurement System (OMS), developed at IIT Kharagpur. The OMS facility works under vacuum environment, in which the test samples are exposed to vacuum conditions over a sufficient period of time. The outgassing measurements for the composite samples were obtained using pressure-rise technique. These studies are useful to quantify the outgassing rate of composite materials under vacuum conditions and to suggest them for manufacturing composite torque tubes used in HTS motors.

Anthelmintic activity of $Clerodendrum$ $viscosum$

Das, Jayanta Kumar,Choudhury, S.,Adhikary, S.,Das, B.,Samanta, S.,Mandal, S.C.,Dey, S.P. 경희한의학연구센터 2011 Oriental Pharmacy and Experimental Medicine Vol.11 No.2

The juice of the fresh leaves of $Clerodendrum$ $viscosum$ is widely used in the treatment of helminthiasis in folklore medicine. In this present study we have investigated the folklore claim methodically and scientifically. The ethanolic and aqueous extracts of leaves and roots of the plant are tested against $Pheretima$ $posthuma$ & $Ascardia$ $galli$ to ascertain their anthelmintic potential. All the extracts showed significant anthelmintic activity in dose dependent manner; the ethanolic extract of root at a dose of 200 mg/ml exhibited better anthelmintic activity than the reference drug, Piperazine citrate (10 mg/ml) against both type of worms.

Anthelmintic activity of Clerodendrum viscosum

Jayanta Kumar Das,S. Choudhury,S. Adhikary,B. Das,S. Samanta,S. C. Mandal,S. P. Dey 경희대학교 융합한의과학연구소 2011 Oriental Pharmacy and Experimental Medicine Vol.11 No.2

The juice of the fresh leaves of Clerodendrum viscosum is widely used in the treatment of helminthiasis in folklore medicine. In this present study we have investigated the folklore claim methodically and scientifically. The ethanolic and aqueous extracts of leaves and roots of the plant are tested against Pheretima posthuma & Ascardia galli to ascertain their anthelmintic potential. All the extracts showed significant anthelmintic activity in dose dependent manner; the ethanolic extract of root at a dose of 200 mg/ml exhibited better anthelmintic activity than the reference drug,Piperazine citrate (10 mg/ml) against both type of worms.

Total Cross Sections for Neutron Nucleus Scattering

S. V. Suryanarayana,H. Naik,S. Ganesan,S. Kailas,R. K. Choudhury,김귀년 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Ramsauer model is well known and widely applied to understand systematics of neutron nucleus total cross sections. In this work, we examined the role of nuclear effective radius parameter (r_0) on Ramsauer model fits of neutron total cross sections. We examined the Ramsauer model global analysis of the experimental neutron total cross sections reported by W. P. Abfalterer, F. B. Bateman, et. al., from 20 MeV to 550 MeV for nuclei ranging from Be to U. The global fits predict within ±8% deviation to data.It has been observed that a finer adjustment of r_0 parameter alone can give very good Ramsauer model description of neutron total scattering data within ±4% deviation. The required r_0 values for Ramsauer model fits are provided as a function of nuclear mass number. In optical model study, we have modified the real part of Koning-Deleroche potentials to fit the neutron total cross sections using SCAT2 code. The modified potentials have a different energy dependence beyond 200 MeV of neutron energy and fit the neutron total cross sections from C to Bi.

Evolution of a honeycomb network of precipitates in a hot-rolled commercial Mg-Y-Nd-Zr alloy

Choudhuri, D.,Meher, S.,Nag, S.,Dendge, N.,Hwang, J.Y.,Banerjee, R. Taylor Francis 2013 Philosophical magazine letters Vol.93 No.7

Effect of Dikegulac on Growth and Alkaloid Production in Catharanthus roseus(L.) G. DON.(Pink flowered)

Choudhury, S.,K. Gupta 한국식물학회 1998 Journal of Plant Biology Vol.41 No.3

Application of sodium-dikegulac reduced plant height with associated increase in branch and leaf number and root biomass in c. roseus (L.) G. DON. ChlorophyII content reduced significantly after first month of 100 and 250 ㎍/㎖ DK application. However, such reduction was replaced by significant rise after forth month in 250 ㎍/㎖ DK application and fifth month in 100 ㎍/㎖ DK application followed by appreciable decline only in 250 ㎍/㎖ DK treatment but 100 ㎍/㎖ DK maintained higher level till harvest. Total sugar content was significantly high during forth and fifth month stage of growth after DK application. Amino acid content was higher during third to fifth month in 100 ㎍/㎖ DK treatment and during third to forth month in 250 ㎍/㎖ DK treatment. Tryptophan, on the other hand showed higher content at the fifth month stage of growth after application of DK in both the concentrations. Leaf and root dry weight as well as total alkaloid content were highest in 100 ㎍/㎖ DK application. DK, therefore, appears to be a potential chemical for increasing biomass and alkaloid content in C. roseus.

FIXED POINTS OF GENERALIZED KANNAN TYPE MAPPINGS IN GENERALIZED MENGER SPACES

Choudhury, Binayak S.,Das, Krishnapada Korean Mathematical Society 2009 대한수학회논문집 Vol.24 No.4

Generalized Menger space introduced by the present authors is a generalization of Menger space as well as a probabilistic generalization of generalized metric space introduced by Branciari [Publ. Math. Debrecen 57 (2000), no. 1-2, 31-37]. In this paper we prove a Kannan type fixed point theorem in generalized Menger spaces. We also support our result by an example.

In-situ synthesis of vanadium pentoxide nanofibre/exfoliated graphene nanohybrid and its supercapacitor applications

Choudhury, Arup,Bonso, Jeliza S.,Wunch, Melissa,Yang, Kap Seung,Ferraris, John P.,Yang, Duck J. Elsevier 2015 Journal of Power Sources Vol.287 No.-

<P><B>Abstract</B></P> <P>A novel nanohybrid material composed of vanadium pentoxide nanofibres (VNFs) and exfoliated graphene were prepared by <I>in-situ</I> growth of VNFs onto graphene nanosheets, and explicated as electrode material for supercapacitor applications. The existence of non-covalent interactions between VNFs and graphene surfaces was confirmed by Raman and Fourier transform infrared (FTIR) spectroscopes. Morphological analysis of the nanohybrid revealed that the VNF layer uniformly grown on the graphene surfaces, producing high specific surface area and good electronic or ionic conducing path. High crystalline structure with small d-spacing of the VNFs on graphene was observed in X-ray diffraction (XRD) analysis. Compared to pristine VNF, the VNF/graphene nanohybrid exhibited higher specific capacitance of 218 F g<SUP>−1</SUP> at current density of 1 A g<SUP>−1</SUP>, higher energy density of 22 Wh kg<SUP>−1</SUP> and power density of 3594 W kg<SUP>−1</SUP>. Asymmetric supercapacitor devices were prepared using the Spectracarb 2225 activated carbon cloth and VNF/graphene nanohybrid as positive and negative electrode, respectively. The asymmetric device exhibited capacitance of 279 F g<SUP>−1</SUP> at 1 A g<SUP>−1</SUP>, energy density of 37.2 Wh kg<SUP>−1</SUP> and power density of 3743 W kg<SUP>−1</SUP>, which are comparable and or superior to reported asymmetric devices consisting of carbon material and metal oxide as electrode components.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Preparation of novel nanohybrid by <I>in-situ</I> growth of V<SUB>2</SUB>O<SUB>5</SUB> nanofibres on graphene. </LI> <LI> Electrochemical characterizations of the nanohybrid for supercapacitor application. </LI> <LI> Maximum capacitance observed for asymmetric devices. </LI> <LI> Energy density of asymmetric devices was 69% higher than that of symmetric device. </LI> </UL> </P>

INDUSTRIAL APPLICATIONS OF THREE COMPUTATIONAL FLUID DYNAMICS

S. E. Kim,D. Choudhury 대한기계학회 1992 International Conference on Fluid Machinery Vol.1 No.1