The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in ASTROSAT, the first Indian Space Observatory. The UVIT instrument has two 375 mm telescopes: one for the far-ultraviolet (FUV) ...channel (1300-1800 ), and the other for the near-ultraviolet (NUV) channel (2000-3000 ) and the visible (VIS) channel (3200-5500 ). UVIT is primarily designed for simultaneous imaging in the two ultraviolet channels with spatial resolution better than 1 8, along with provisions for slit-less spectroscopy in the NUV and FUV channels. The results of in-orbit calibrations of UVIT are presented in this paper.
Results of the initial calibration of the Ultra-Violet Imaging Telescope (UVIT) were reported earlier by Tandon et al. The results reported earlier were based on the ground calibration as well as the ...first observations in orbit. Some additional data from the ground calibration and data from more in-orbit observations have been used to improve the results. In particular, extensive new data from in-orbit observations have been used to obtain (a) new photometric calibration that includes (i) zero points, (ii) flat fields, and (iii) saturation; (b) sensitivity variations; (c) spectral calibration for the near ultraviolet (NUV; 2000-3000 ) and far ultraviolet (FUV; 1300-1800 ) gratings; (d) point-spread function; and (e) astrometric calibration including distortion. Data acquired over the last three years show continued good performance of UVIT with no reduction in sensitivity in both UV channels.
We introduce the notion of quantum dissension for a three-qubit system as a measure of quantum correlations. We use three classically equivalent expressions of three-variable mutual information. ...Their differences are zero classically but not so in quantum domain. It generalizes the notion of quantum discord to a multipartite system. There can be multiple definitions of the dissension depending on the nature of projective measurements done on the subsystems. As an illustration, we explore the consequences of these multiple definitions and compare them for three-qubit pure and mixed GHZ and W states. We find that unlike discord, dissension can be negative. This is because measurement on a subsystem may enhance the correlations in the rest of the system. Furthermore, when we consider a bipartite split of the system, the dissension reduces to discord. This approach can pave a way to generalize the notion of quantum correlations in the multiparticle setting.
The proper identification of the existence of the boiling phenomena in a process from the trend of the Nukiyama pool-boiling curve (Q versus ∆T) is not appropriate as it does not always reveal right ...information. All the heating and cooling around the boiling point mimic the boiling behavior; however, these are not always actually a part of the boiling process. Therefore, the proper identification and discrimination among boiling methodologies need to be revealed as the information on the discussed issues are not available in the open literature. Hence, an attempt has been made to develop a condition describing the existence of boiling behavior in heating or quenching process and protocol to identify various boiling regimes. In the current work, the developed conditions (1/ St) are validated with various type of boiling processes and the protocol (i.e. based on the slope of h versus ∆T curve rather than boiling curve) is also valid for the identification of proper boiling regime.
The integrated microbial genomes and metagenomes (IMG/M) system provides support for comparative analysis of microbial community aggregate genomes (metagenomes) in a comprehensive integrated context. ...IMG/M integrates metagenome data sets with isolate microbial genomes from the IMG system. IMG/M's data content and analytical capabilities have been extended through regular updates since its first release in 2007. IMG/M is available at http://img.jgi.doe.gov/m. A companion IMG/M systems provide support for annotation and expert review of unpublished metagenomic data sets (IMG/M ER: http://img.jgi.doe.gov/mer).
We study absorption spectra and two photon absorption coefficient of expanded porphyrins (EPs) by the density matrix renormalization group (DMRG) technique. We employ the Pariser–Parr–Pople (PPP) ...Hamiltonian which includes long-range electron–electron interactions. We find that, in the 4n+2 EPs, there are two prominent low-lying one-photon excitations, while in 4n EPs, there is only one such excitation. We also find that 4n+2 EPs have large two-photon absorption cross sections compared to 4n EPs. The charge density rearrangement in the one-photon excited state is mostly at the pyrrole nitrogen site and at the meso carbon sites. In the two-photon states, the charge density rearrangement occurs mostly at the aza-ring sites. In the one-photon state, the C–C bond length in aza rings shows a tendency to become uniform. In the two-photon state, the bond distortions are on C–N bonds of the pyrrole ring and the adjoining C–C bonds which connect the pyrrole ring to the aza or meso carbon sites.
The objective of the current work is to enhance the spray cooling by changing the orientation of the nozzle with different additives (acetone, methanol, ethanol, benzene, n-hexane, tween 20 and salt) ...in water. The experiments are carried out by upward, downward and both upward and downward facing sprays. The optimization result depicts that the spray produced by upward facing spray gives higher heat flux than the downward facing spray and also cooling by both the upward and downward facing spray simultaneously produces better result than the individual. Further experiments with both upward and downward facing spray by using different coolants reveal that in case of cooling by ethanol (500 ppm) + water mixture, the maximum enhancement of surface heat flux (~2.57 MW/m
2
) and cooling rate (204 °C/s) is observed. However, the minimum surface heat flux is achieved in case of methanol (100 ppm) + water due to higher contact angle (71
0
) among all the considered coolants.
•Obligations in achieving high cooling rates by spray cooling are overcome.•Heat removal is enhanced by spray cooling with coolants-ethanol and tween20 in water.•Achieved CHF with Tween ...20-ethanol-water mixture is 1.6 times higher than pure water.•Maximum obtained cooling rate is 141°C/s in case of ethanol-water-Tween 20 mixture.
Spray cooling is an efficient cooling technology over conventional cooling methods such as jet cooling on run-out table. However, the achieved cooling rates are still not enough for some specific applications. The main obligation in achieving high cooling rates is the occurrence of film boiling phenomenon. In the absence of any information on the heat transfer augmentation techniques of spray cooling at very high initial surface temperatures (∼900°C), the present work deals with enhancement of spray cooling at the aforesaid initial temperature by using different coolants which enhance the heat removal rate by creating high heat transfer area and decreasing the stability of the vapour and liquid film on the hot plate. For the experimental investigation, spray cooling experiments were conducted at 900°C initial surface temperature on a 6mm thick AISI 304 steel plate (100×100mm) by using different coolants. The surface temperature and heat flux have been calculated using INTEMP software. For the understanding of heat transfer mechanism, the coolants properties at different concentrations and spray behavior at different flow rates were measured. The ethanol-water spray cooling demonstrates that the heat removal rate increases with increasing ethanol concentration by decreasing contact angle. The reduction in the contact angle results in increasing heat transfer area and decreasing the vapour-bubble coalescence rate. However, beyond ethanol concentration of 500ppm, the excessive occurrence of the foaming decreases the heat removal rate. Further, the heat transfer rate is tried to enhance by adding tween-20 surfactant which lowers the contact angle significantly with the controlled characteristics of foaming. In the case of ethanol-water-tween 20 mixture spray, the achieved critical heat flux (2.1MW/m2) is 1.6 times that of pure water (1.3MW/m2). Due to the above mentioned favorable conditions for fast cooling, a maximum cooling rate of 141°C/s is achieved.
The impact of global financial crisis (GFC) was well pervasive with no exception to Brazil, Russia, India, China and South Africa (BRICS) nations. Banking being the conduit to the market was affected ...severely in many economies including BRICS, where credit risk emanated from non-performing loans (NPL) was ascribed as the main cause of concern. With the help of The World Bank data set of pre-GFC and post-GFC, this article attempts to look into the credit risk testing practices of BRICS. The Chow’s F-test based on NPL shows no shift in the profitability of banking across all the five economies, whereas a shift in the capital adequacy ratio (CAR) of Russia, India and China in post-crisis years was visible. The BRICS though has different political set-ups follow the international practice of credit risk stress testing for assessing the resilience of their banking sector. Before the crisis, International Monetary Fund (IMF) assessed stress testing for credit risk was in place with BRICS (except India) and currently all the countries are conducting such tests, either independently by their own central banks or with the help of IMF. Bank-specific tests, however, were not found. While India and South Africa are conducting such tests regularly, other three economies are lacking behind. Most of the assessments adopt simulated scenario analysis as well as sensitivity tests for credit risk. While India has been conducting the tests at macro, sector and bank group levels, others are concentrating on macro-level and bank group level. Though variations in selecting variables are found across BRICS, it was found to be very insignificant. The cautions that came along with these tests were mostly found for next 1 to 2 years indicating the test lacuna in predicting bank crisis on a long term.
The significant reduction of Leidenfrost effect during the cooling of high carbon steel plate by different potential cooling methodologies does not assure their successful implementation in the fast ...quenching of high carbon steel plate due to the formation of oxide layer of comparatively low thermal conductivity on the quenching surface. Therefore, the role of oxide layer in case of different potential cooling methodologies needs to be addressed. In the present study, the effect of oxide layer on heat transfer rate in case of upward, downward, and both upward and downward facing spray with additives has been investigated by conducting and comparing the heat transfer cooling data of an AISI 1020 plate with the AISI 304 plate. The comparison clearly depicts that the formation of oxide layer during cooling significantly hinders the heat transfer rate in nucleate boiling regime; however, the reverse phenomenon is observed in transition boiling regime. Among all the coolants, the least effect of oxide layer on enhancement is obtained in case of NaCl (0.4 M)-added water spray due to the deposition of salt on the evaporating surface. The X-ray diffraction analysis and the thickness of the formed oxide layer clearly assert that the coolant depicting minimum oxidation characteristic is preferred.
Abbreviations: AISI: American iron and steel institute; OES: Optical emission spectrophotometer; CHF: Critical heat flux, MW/m
2
; IHF: Initial heat flux, MW/m
2
; T
CHF
: Temperature at which CHF is achieved, °C; Fps: Frames per second; XRD: X-Ray diffraction; k
1
: Thermal conductivity of steel plate, W/m °C; k
2
: Thermal conductivity of oxide layer, W/m °C; k
3
: Thermal conductivity of coolant, W/m °C; X: x-axis, mm; Y: y-axis, mm; Z: z-axis, mm
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Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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