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.

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.

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.

Biochar Application to Soil and its Effect on Soil Health

S M Imamul Huq,M. Shahjahan Choudhury,M. Tanvir Ahmed Choudhury,Kishan Mahmud,Tazeen Fatima Khan,K Tahera Khan,Nadia Noor 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Total Cross Sections for Neutron Nucleus Scattering

Suryanarayana, S.V.,Naik, H.,Ganesan, S.,Kailas, S.,Choudhury, R. K.,Kim, Guinyun Korean Physical Society 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.2

Bioactivity of the methanol extract of Excoecaria agallocha Linn.(Euphorbiaceae)

Rajia, S.,Alamgir, M.,Shahriar, M.,Choudhuri, M.S.K. Kyung Hee Oriental Medicine Research Center 2006 Oriental pharmacy and experimental medicine Vol.6 No.2

The methanol extract and residual methanol fraction of Excoecaria agallocha L. (Euphorbiaceae) stem bark was investigated in this study by wheat rootlet and shoot growth inhibition, and antimicrobial bioassay. The methanol extract and residual methanol fraction showed high inhibitory effect on both the wheat rootlet (82-89%) and shoot growth (85-90%) compared to control. The methanol extract showed a better and dose related inhibition on both the rootlet and shoot growth compared to residual methanol fraction. The $IC_{50}$ value of methanol extract for rootlet and shoot were $2.88\;{\mu}g/ml$ and $2.32\;{\mu}g/ml$, and of residual methanol fraction for rootlet and shoot were $7.91\;{\mu}g/ml$ and $4.45\;{\mu}g/ml$. The methanol extract and residual methanol fraction did not show any antibacterial activity against the tested microorganisms of clinical isolates Escherichia coli, Staphylococcus aureous, Pseudomonas aeruginosa, Proteus vulgaris and Bacillus subtilis. The plant has the potential to be a source of novel cytotoxic compound(s).

Design and Construction of Nitrogen Liquefier

B. K, Choudhury,R. K. Sahoo,S. K. Sarangi 국제문화기술진흥원 2015 International Journal of Advanced Culture Technolo Vol.3 No.2

The design and construction of nitrogen liquefier begins with the process design of the cycle. The simulation of the cycles has been done using the software Aspen HYSYS. The compressor unit is available in the laboratory. Two number of high effectiveness, vacuum brazed aluminum plate fin heat exchangers are designed and fabricated. Turboexpander is designed and all of its components are fabricated. A suitable modification has been done with a precession needle valve to operate as a long stem JT valve. For separating the liquid, a phase separator is designed and fabricated. All the components are assembled inside a double walled cold box with pipes as per the process need. The necessary pressure, temperatureand other measuring instruments, valves and safety devices are mounted on the liquefier. After successful running of the liquefier, for the mass flow rate of 296 kg/hr for gaseous nitrogen, it is expected to deliver 17.44 lit/hr of liquid nitrogen.

A sensitive fluorescent probe for the polar solvation dynamics at protein-surfactant interfaces

Singh, P.,Choudhury, S.,Singha, S.,Jun, Y.,Chakraborty, S.,Sengupta, J.,Das, R.,Ahn, K. H.,Pal, S. Royal Society of Chemistry 2017 Physical chemistry chemical physics Vol.19 No.19

<P>Relaxation dynamics at the surface of biologically important macromolecules is important taking into account their functionality in molecular recognition. Over the years it has been shown that the solvation dynamics of a fluorescent probe at biomolecular surfaces and interfaces account for the relaxation dynamics of polar residues and associated water molecules. However, the sensitivity of the dynamics depends largely on the localization and exposure of the probe. For noncovalent fluorescent probes, localization at the region of interest in addition to surface exposure is an added challenge compared to the covalently attached probes at the biological interfaces. Here we have used a synthesized donor-acceptor type dipolar fluorophore, 6-acetyl-(2-((4-hydroxycyclohexyl)(methyl) amino) naphthalene) (ACYMAN), for the investigation of the solvation dynamics of a model protein-surfactant interface. A significant structural rearrangement of a model histone protein (H1) upon interaction with anionic surfactant sodium dodecyl sulphate (SDS) as revealed from the circular dichroism (CD) studies is nicely corroborated in the solvation dynamics of the probe at the interface. The polarization gated fluorescence anisotropy of the probe compared to that at the SDS micellar surface clearly reveals the localization of the probe at the protein-surfactant interface. We have also compared the sensitivity of ACYMAN with other solvation probes including coumarin 500 (C500) and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran (DCM). In comparison to ACYMAN, both C500 and DCM fail to probe the interfacial solvation dynamics of a model protein-surfactant interface. While C500 is found to be delocalized from the protein-surfactant interface, DCM becomes destabilized upon the formation of the interface (protein-surfactant complex). The timescales obtained from this novel probe have also been compared with other femtosecond resolved studies and molecular dynamics simulations.</P>

Wear behaviors of single-layer and multi-layer coated carbide inserts in high speed machining of hardened AISI 4340 steel

Satish Chinchanikar,S. K. Choudhury 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

Flank wear progression and wear mechanisms of uncoated, coated with PVD applied single-layer TiAlN, and CVD applied multi-layer MT-TiCN/Al2O3/TiN cemented carbide inserts were analyzed during dry turning of hardened AISI 4340 steel (35 HRC). Experimental observations indicate that by applying a coating to the uncoated insert the limiting cutting speed increase from 62 to 200 m/min, which further extends up-to 300-350 m/min when using multi-layer coating scheme. Relatively lower wear rate seen when using single-layer TiAlN coated inserts. However, after removal of the thin layer of coating the wear rate increase rapidly, subsequently dominates the wear rate of multi-layer coated inserts. Cutting forces; especially axial and radial components have also shown the similar behavior and increase rapidly when the tool failure occurs. Flank wear, crater wear and catastrophic failure are the dominant forms of tool wear. Digital microscope and SEM images coupled with elemental analysis (EDAX) have been taken at various stages of tool life for understanding the wear mechanisms.

Development and Testing of 2G High Temperature Superconducting (HTS) Field Coils for HTS Synchronous Machines

Muralidhar Bathula V. A. S.,Sharma D. K.,Choudhury U. K.,Rao V. V. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3

High temperature superconducting (HTS) synchronous machines are compact and light weight machines with higher torque to weight ratio, lower noise and better dynamic response for strategic and critical industrial applications. The development of HTS fi eld coil is one of the main technological challenges in realizing the HTS synchronous machines, as it involves the selection of HTS tape, winding technology, handling of the HTS tape while winding on a winding machine and testing of the developed HTS coil at desired cryogenic temperatures. With advancements in HTS tape technology, recent 2G HTS tapes are off ered with higher engineering current densities with respect to 1G HTS tapes even at higher magnetic fi elds. Hence, the replacement of 1G HTS fi eld coils of previously designed 200 kVA HTS synchronous machine with 2G HTS fi eld coils at the same operating cryo-temperature shows a potential to enhance its capacity to 350 kVA (more than 75% increase in machine output). In the present work the details of design, development and testing of a double pancake type 2G HTS fi eld coil are presented for capacity enhancement of earlier 1G based 200kVA HTS synchronous machine.