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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.
Acquisition, Processing and Image Generation System for Camera Data Onboard Spacecraft
C.V.R Subbaraya Sastry,G.S Narayan Rao,N Ramakrishna,V.K Hariharan International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.3
The primary goal of any communication spacecraft is to provide communication in variety of frequency bands based on mission requirements within the Indian mainland. Some of the spacecrafts operating in S-band utilizes a 6m or larger aperture Unfurlable Antenna (UFA for S-band links and provides coverage through five or more S-band spot beams over Indian mainland area. The Unfurlable antenna is larger than the satellite and so the antenna is stowed during launch. Upon reaching the orbit, the antenna is deployed using motors. The deployment status of any deployment mechanism will be monitored and verified by the telemetered values of micro-switch position before the start of deployment, during the deployment and after the completion of the total mechanism. In addition to these micro switches, a camera onboard will be used for capturing still images during primary and secondary deployments of UFA. The proposed checkout system is realized for validating the performance of the onboard camera as part of Integrated Spacecraft Testing (IST) conducted during payload checkout operations. It is designed for acquiring the payload data of onboard camera in real-time, followed by archiving, processing and generation of images in near real-time. This paper presents the architecture, design and implementation features of the acquisition, processing and Image generation system for Camera onboard spacecraft. Subsequently this system can be deployed in missions wherever similar requirement is envisaged.
Singh, V.,Sivaramaiah, G.,Mohapatra, M.,Rao, J. L.,Singh, N.,Pathak, M. S.,Singh, P. K.,Dhoble, S. J. Springer Science + Business Media 2017 Journal of Electronic Materials Vol.46 No.2
<P>GdAlO3 phosphor samples have been prepared by a solution combustion method. X-ray diffraction analysis revealed that the GdAlO3 phosphor stabilized in orthorhombic phase. The optical absorption spectrum showed bands due to Gd3+ ions as well as defect level in the host. The excitation spectrum exhibited a dominant band with maximum at 273 nm. Upon excitation at 273 nm, ultraviolet-B (UV-B) emission with maximum at 312 nm was observed from the undoped sample, being attributed to P-6(7/2) -> S-8(7/2) transition of Gd3+ ion. The UV-B emission was enhanced at liquid-nitrogen temperature (77 K), most probably due to increased ground-state population according to the Boltzmann distribution law. Electron spin resonance spectra of samples at both room and liquid-nitrogen temperature exhibited resonance signals at g ae 2, attributed to Gd3+ ions arranged with octahedral symmetry linked via oxygen bridges. Various magnetic and thermodynamic parameters for the phosphor system were evaluated by standard procedures. Correlation of these values with the optical properties suggested that the GdAlO3 phosphor can be effectively used as an UV-B light source for industrial applications at room temperature.</P>
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.
Chemically synthesized PbS Nano particulate thin films for a rapid NO<sub>2</sub> gas sensor
Burungale, Vishal V.,Devan, Rupesh S.,Pawar, Sachin A.,Harale, Namdev S.,Patil, Vithoba L.,Rao, V. K.,Ma, Yuan-Ron,Eun Ae, Jo,Kim, Jin H.,Patil, Pramod S. De Gruyter 2016 MATERIALS SCIENCE -WROCLAW- Vol.34 No.1
<P><B>Abstract</B></P><P>Rapid NO<SUB>2</SUB>gas sensor has been developed based on PbS nanoparticulate thin films synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR) method at different precursor concentrations. The structural and morphological properties were investigated by means of X-ray diffraction and field emission scanning electron microscope. NO<SUB>2</SUB>gas sensing properties of PbS thin films deposited at different concentrations were tested. PbS film with 0.25 M precursor concentration showed the highest sensitivity. In order to optimize the operating temperature, the sensitivity of the sensor to 50 ppm NO<SUB>2</SUB>gas was measured at different operating temperatures, from 50 to 200<SUP>°</SUP>C. The gas sensitivity increased with an increase in operating temperature and achieved the maximum value at 150<SUP>°</SUP>C, followed by a decrease in sensitivity with further increase of the operating temperature. The sensitivity was about 35 % for 50 ppm NO<SUB>2</SUB>at 150<SUP>°</SUP>C with rapid response time of 6 s. T90 and T10 recovery time was 97 s at this gas concentration.</P>
K. Sambasiva Rao,T. V. Beatriceveena,C. S. Angani,Lucky Agarwal 한국자기학회 2020 Journal of Magnetics Vol.25 No.3
Pulsed eddy current (PEC) testing is an electromagnetic nondestructive evaluation (NDE) technique which is used for detection and classification of flaws. This paper presents an approach for the extraction of novel timedomain flaw parameters viz. amplitude ratio (V1/V0) and time constant (τ) for detection and classification of different flaws. Experiments are carried out on stainless steel (SS-316) plate with artificial EDM notches whose width (1.0 mm & 3.0 mm) and depth (1.0 mm to 6.0 mm) varied. The proposed approach can classify both surface and sub-surface flaws in an 8.0 mm thick SS plate. The advantage of the proposed approach is that it doesn’t require a reference signal subtraction or signal processing methodologies for the detection and classification of flaws.
Kim, H.J.,Suh, S.M.,Rao, S.S.,Punnoose, D.,Tulasivarma, C.V.,Gopi, Chandu.V.V.M.,Kundakarla, N.,Ravi, S.,Durga, I.K. Elsevier Sequoia 2016 Journal of Electroanalytical Chemistry Vol.777 No.-
<P>To make quantum dot-sensitized solar cells (QDSSCs) more attractive, it is necessary for the power conversion efficiency (PCE) to be comparable to those of other emerging solar cells. Currently, copper sulfide (CuS) and nickel sulfide (NiS) are commonly used counter electrodes (CEs) in high-efficiency QDSSCs because of their low toxicity, environmental compatibility, and superior electrocatalytic activity in the presence of polysulfide electrolyte. For the first time, novel CuS/NiS electrodes were prepared by facile chemical bath deposition method. This article describes the effect of NiS layer on CuS film for preventing the recombination process to enhance the performance of QDSSCs. Under one sun illumination, the CE with the optimized CuS/NiS composite film exhibits higher short-circuit current density (J(sc)), open-circuit voltage (V-oc), and PCE of 12.47 mA cm(-2), 0.599 V, and 4.19%, respectively. These values are much higher than those of bare CuS (2.73%), NiS (1.82%), and Pt CEs (1.16%). This enhancement is mainly attributed to the improved surface morphology, higher sulfur atomic percentage with Cu vacancies, rapid electron transport, and lower electron recombination rate for the polysulfide electrolyte. Characterization with, cyclic voltammetry, and Tafel polarization was performed to study the reasons for efficient CE performance. (C) 2016 Elsevier B.V. All rights reserved.</P>
Latha, K. Lavanya,Rao, T.V.S.S.,Rao, J. V. Krishna,Jayaraj, S.,Reddy, N. Sivarami,Naik, S. Sankar Korean Society of Sericultural Science 2008 International Journal of Industrial Entomology Vol.17 No.2
A field study on self trap cropping system in controlling tukra mealy bug Maconellicoccus hirsutus Green) incidence on mulberry (Morus spp.; V-1 variety; $3'{\times}3'$ spacing) gardens was undertaken in selected sericulture farmers' mulberry gardens of Pydeti village (Parigi Mandal, Anantapur District, Andhra Pradesh, India). The study was conducted for three years (2004, 2005 and 2006). Four treatments (T0; control/no treatment, T1; self trap cropping rows with 10 row interval, T2; self trap cropping rows with 10 row interval and treating these rows only with 0.5% neem oil emulsion and T3; self trap cropping rows with 10 rows intervals and treating all the mulberry rows including self trap cropping rows with 0.5% neem oil emulsion) were considered. The results indicated that the incidence increased in T0 and T1 while the same suppressed in T2 and T3. The suppression (%) of tukra incidence between T2 and T3 was not significant. Hence, T2 only was recommended to farmers as its economical viable practice. The results are discussed based on the importance of tukra, its suppression and cost of treatment.
( K. Lavanya Latha ),( T. V. S. S. Rao ),( J. V. Krishna Rao ),( S. Jayaraj ),( N. Sivarami Reddy ),( S. Sankar Naik ) 한국잠사학회 2008 International Journal of Industrial Entomology Vol.17 No.2
A field study on self trap cropping system in controlling tukra mealy bug Maconellicoccus hirsutus Green) incidence on mulberry (Morus spp.; V-1 variety; 3`x3` spacing) gardens was undertaken in selected sericulture farmers` mulberry gardens of Pydeti village (Parigi Mandal, Anantapur District, Andhra Pradesh, India). The study was conducted for three years (2004, 2005 and 2006). Four treatments (T0; control/no treatment, T1; self trap cropping rows with 10 row interval, T2; self trap cropping rows with 10 row interval and treating these rows only with 0.5% neem oil emulsion and T3; self trap cropping rows with 10 rows intervals and treating all the mulberry rows including self trap cropping rows with 0.5% neem oil emulsion) were considered. The results indicated that the incidence increased in T0 and T1 while the same suppressed in T2 and T3. The suppression (%) of tukra incidence between T2 and T3 was not significant. Hence, T2 only was recommended to farmers as its economical viable practice. The results are discussed based on the importance of tukra, its suppression and cost of treatment.