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In this study, we extracted the amplitudes of the gravity waves (GWs)from the neutral densities measured in situ by the neutral gas and ion mass spectrometer aboard the Mars atmosphere and volatile evolution mission. The spatial and temporal variabilities of the GWs show that solar activity (the F10.7 cm solar flux corrected for a heliocentric distance of 1.66 AU), solar insolation, and the lower atmospheric dust are the dominant drivers of the GW variability in the thermosphere. We developed a methodology in which a linear regression analysis has been used to disentangle the complex variabilities of the GWs. The three dominant drivers could account for most of the variability in the GW amplitudes. Variability caused by the sources of GWs and the effects of winds and the global circulation in the mesosphere and lower thermosphere are the other factors that could not be addressed. The results of the present study show that for every 100 sfu increase in the solar activity, the GW amplitudes in the thermosphere decrease by ~9%. Solar insolation drives the diurnal, seasonal and latitudinal variations of ~9%, ~4% and ~6%, respectively. Using the historical data of the dust opacity and solar activity, we estimated the GW amplitudes of the Martian thermosphere from MY 24 to MY 35. The GW amplitudes were significantly reduced during the maximum of solar cycle 23 and were highest in the solar minimum. The global dust storms of MY 25, 28, and 34 lead to significant enhancements in the GW amplitudes., Comment: Accepted for publication in the astrophysical journal; 18 pages

The quality of assessment determines the quality of learning, and is characterized by validity, reliability and difficulty. Mastery of learning is generally represented by the difficulty levels of assessment items. A very large number of variables are identified in the literature to measure the difficulty level. These variables, which are not completely independent of one another, are categorized into learner dependent, learner independent, generic, non-generic and score based. This research proposes a model for predicting the difficulty level of assessment items in engineering courses using learner independent and generic variables. An ordinal regression model is developed for predicting the difficulty level, and uses six variables including three stimuli variables (item presentation, usage of technical notations and number of resources), two content related variables (number of concepts and procedures) and one task variable (number of conditions). Experimental results from three engineering courses provide around 80% accuracy in classification of items using the proposed model., Comment: 16 pages

We present the first results of eight Globular Clusters (GCs) from the AstroSat/UVIT Legacy Survey program GlobULeS based on the observations carried out in two FUV filters (F148W and F169M). The FUV-optical and FUV-FUV color-magnitude diagrams (CMDs) of GCs with the proper motion membership were constructed by combining the UVIT data with HST UV Globular Cluster Survey (HUGS) data for inner regions and Gaia Early Data Release (EDR3) for regions outside the HST's field. We detect sources as faint as F148W $\sim$ 23.5~mag which are classified based on their locations in CMDs by overlaying stellar evolutionary models. The CMDs of 8 GCs are combined with the previous UVIT studies of 3 GCs to create stacked FUV-optical CMDs to highlight the features/peculiarities found in the different evolutionary sequences. The FUV (F148W) detected stellar populations of 11 GCs comprises 2,816 Horizontal Branch (HB) stars (190 Extreme HB candidates), 46 post-HB (pHB), 221 Blue Straggler Stars (BSS), and 107 White Dwarf (WD) candidates. We note that the blue HB color extension obtained from F148W$-$G color and the number of FUV detected EHB candidates are strongly correlated with the maximum internal Helium (He) variation within each GC, suggesting that the FUV-optical plane is the most sensitive to He abundance variations in the HB. We discuss the potential science cases that will be addressed using these catalogues including HB morphologies, BSSs, pHB, and, WD stars., Comment: Accepted for publication in MNRAS; 24 pages, 20 Figures, 6 Tables

We use a genetic algorithm (GA) as a design aid for determining the optimal provisioning of entangled photon spectrum in flex-grid quantum networks with arbitrary numbers of channels and users. After introducing a general model for entanglement distribution based on frequency-polarization hyperentangled biphotons, we derive upper bounds on fidelity and entangled bit rate for networks comprising one-to-one user connections. Simple conditions based on user detector quality and link efficiencies are found that determine whether entanglement is possible. We successfully apply a GA to find optimal resource allocations in four different representative network scenarios and validate features of our model experimentally in a quantum local area network in deployed fiber. Our results show promise for the rapid design of large-scale entanglement distribution networks., Comment: 13 pages, 8 figures

The term robot generally refers to a machine that looks and works in a way similar to a human. The modern industry is rapidly shifting from manual control of systems to automation, in order to increase productivity and to deliver quality products. Computer-based systems, though feasible for improving quality and productivity, are inflexible to work with, and the cost of such systems is significantly high. This led to the swift adoption of automated systems to perform industrial tasks. One such task of industrial significance is of picking and placing objects from one place to another. The implementation of automation in pick and place tasks helps to improve efficiency of system and also the performance. In this paper, we propose to demonstrate the designing and working of an automated robotic arm with the Machine Learning approach. The work uses Machine Learning approach for object identification detection and traversal, which is adopted with Tensor flow package for better and accurate results.

We present the far-UV (FUV) photometry of images acquired with UVIT on AstroSat to probe the horizontal branch (HB) population of the Galactic globular cluster NGC 2298. UV-optical color-magnitude diagrams (CMDs) are constructed for member stars in combination with HST UV Globular Cluster Survey (HUGS) data for the central region and Gaia and ground-based photometric data for the outer region. Blue HB (BHB) sequence with a spread and four hot HB stars are detected in all FUV-optical CMDs and are compared with theoretical updated BaSTI isochrones and synthetic HB models with a range in helium abundance, suggesting that the hot HB stars are helium enhanced when compared to the BHB. The estimated effective temperature, radius, and luminosity of HB stars, using best SED fits, were compared with various HB models. BHB stars span a temperature range from 7,500-12,250 K. The three hot HB stars have 35,000-40,000 K, whereas one star has around 100,000K. We suggest the following evolutionary scenarios: two stars are likely to be the progeny of extreme HB (EHB) stars formed through an early hot-flasher scenario; one is likely to be an EHB star with probable helium enrichment, the hottest HB star is about to enter the WD cooling phase, could have evolved from BHB phase. Nevertheless, these are interesting spectroscopic targets to understand the late stages of evolution., Comment: 25 pages, 12 figures, 5 tables, Accepted for publication in ApJ

Over the last 5 years, UVIT has completed observations of more than 500 proposals with ~ 800 unique pointings. In addition, regular planned monitoring observations have been made and from their analysis various key parameters related to in orbit performance of UVIT have been quantified. The sensitivities of the UV channels have remained steady indicating no effect of potential molecular contamination confirming the adequacy of all the protocols implemented for avoiding contamination. The quality of the PSF through the years confirms adequacy of thermal control measures. The early calibrations obtained during the Performance Verification (PV) phase have been further revised for more subtle effects. These include flat fields and detector distortions with greater precision. The operations of UVIT have also evolved through in orbit experience, e.g. tweaking of operational sequencing, protocol for recovery from bright object detection (BOD) shutdowns, parameters for BOD thresholds, etc. Finally, some effects of charged particle hits on electronics led to opimised strategy for regular resetting. The Near-UV channel was lost in one of such operations. All the above in-orbit experiences are presented here., Comment: Accepted for publication in Journal of Astrophysics & Astronomy, 11 pages, 10 figures, 1 table

The spectral region between 1250 Angstroms - 3000 Angstroms contains important spectral lines to understand the morphological structures and evolution of planetary nebulae. This is the region sampled by UVIT through various filter bands both in the continuum and in emission lines (e.g. C IV, He I, Mg II etc.). We have mapped several planetary nebulae with different characteristics, ranging in morphology from bipolar to wide and diffuse, and in various states of ionization, comparing the UV with the x-ray morphologies wherever the x-ray images were also available. The major unanticipated discovery with UVIT has been the detection of previously undetected, cold, fluorescent, molecular hydrogen gas surrounding some planetary nebulae. This may be a possible solution to the missing mass problem. Here we present a review of our studies so far done (both published and on going) with UVIT., Comment: 28 pages, 21 figures, 1 table, accepted to J. Astrophys. Astr

We present the UV photometry of the globular cluster NGC 1261 using images acquired with the Ultraviolet Imaging Telescope (UVIT) on-board ASTROSAT. We performed PSF photometry on four near-UV (NUV) and two far-UV (FUV) images and constructed UV colour-magnitude diagrams (CMDs), in combination with HST, Gaia, and ground-based optical photometry for member stars. We detected the full horizontal branch (HB) in NUV, blue HB in the FUV and identified two extreme HB (EHB) stars. HB stars have a tight sequence in UV-optical CMDs well-fitted with isochrones generated (12.6 Gyr age, [Fe/H] = -1.27 metallicity) using updated BaSTI-IAC models. Effective temperatures (Teff), luminosities and radii of bright HB stars were estimated using spectral energy distribution. As we detect the complete sample of UV bright HB stars, the hot end of the HB distribution is found to terminate at the G-jump (Teff ~ 11500 K). The two EHB stars, fitted well with single spectra, have Teff= 31,000 K and a mass = 0.495Msun and follow the same Teff-Radius relation of the blue HB stars. We constrain the formation pathways of these EHB stars to extreme mass loss in the RGB phase (either due to rotation or enhanced Helium), OR early hot-flash scenario., Comment: 13 pages, 9 figures, 3 tables, Accepted for publication in MNRAS

We present the results obtained from the UV photometry of the globular cluster NGC 1261 using Far-UV (FUV) and Near-UV (NUV) images acquired with the Ultraviolet Imaging Telescope (UVIT) onboard the Astrosat satellite. We utilized the UVIT data combined with HST, GAIA, and ground-based optical photometric data to construct the different UV colour-magnitude diagrams (CMDs). We detected blue HB (BHB), and two extreme HB (EHB) stars in FUV, whereas full HB, i.e., red HB (RHB), BHB as well as EHB is detected in NUV CMDs. The 2 EHB stars, identified in both NUV and FUV, are confirmed members of the cluster. The HB stars form a tight sequence in UV-optical CMDs, which is almost aligned with Padova isochrones. This study sheds light on the significance of UV imaging to probe the HB morphology in GCs., Comment: 7 Pages, 4 Figures, Accepted for publication in JAA

We have detected CH$^{+}$ and CH molecular absorption lines from the young compact planetary nebula IC 4997 from high resolution optical spectra. A high-resolution infra-red (H and K bands) spectrum provides detection of H$_2$ emission lines amongst many other lines. The H$_2$ lines provide an excitation temperature of 2100 K which may result from UV fluorescence in the envelope or from shocks formed at the interface between an expanding outflow of ionized gas and the neutral envelope ejected when the star was on the AGB. It is suggested that the CH$^+$ may result from the endothermic reaction C + H$_2$ $\rightarrow$ CH$^+$ + H. Intriguingly, CH$^{+}$ and also CH show a higher expansion velocity than H$_{\rm 2}$ emission suggesting they may be part of the post-shocked gas., Comment: 12 pages, 2 tables, 6 figures, accepted for publication in Publications of the Astronomical Society of the Pacific (PASP)