6 research outputs found
Safe Human Robot-Interaction using Switched Model Reference Admittance Control
Physical Human-Robot Interaction (pHRI) task involves tight coupling between
safety constraints and compliance with human intentions. In this paper, a novel
switched model reference admittance controller is developed to maintain
compliance with the external force while upholding safety constraints in the
workspace for an n-link manipulator involved in pHRI. A switched reference
model is designed for the admittance controller to generate the reference
trajectory within the safe workspace. The stability analysis of the switched
reference model is carried out by an appropriate selection of the Common
Quadratic Lyapunov Function (CQLF) so that asymptotic convergence of the
trajectory tracking error is ensured. The efficacy of the proposed controller
is validated in simulation on a two-link robot manipulator
Assessment of the Level and Health Risk of Fluoride and Heavy Metals in Commercial Toothpastes in Bangladesh
Toothpaste is one of the daily essentials, and good quality control practices over it are very important to protect the oral public health from adverse effects. The current study aimed to assess the concentration of fluoride and heavy metals, physicochemical properties in ten different toothpaste samples in Bangladesh, followed by related health risk analysis. pH, moisture content, Fâ, As, Cu, Pb contents were measured by membrane electrode, thermogravimetric, SPADNS, HG-AAS, flame-AAS methods, respectively. The results were compared to the specification of the packet and Bangladesh Standard and Testing Institute (BSTI) standard. The physicochemical properties well-matched the formulation standard values. The moisture content was 27.18 ± 2.20 to 52.10 ± 5.01%, with 50% of the samples in permissible limit but the pH of all the samples (6.40-8.60) was within the standard limit. Available Fâ, Cu, Pb, and As content ranged from 803â1617, 2.78â13.10, 0.27â2.12, and 0.027â0.637 mg/Kg, respectively. Fâ content in 80% toothpaste did not meet the packet specification and was higher than BSTI standard, though heavy metals were within the BSTI limit. Hazard quotient (HQ) and HI (Hazard Index) analysis revealed that toothpaste safe from heavy metal related to health risk
In-orbit Performance of UVIT on ASTROSAT
We present the in-orbit performance and the first results from the
ultra-violet Imaging telescope (UVIT) on ASTROSAT. UVIT consists of two
identical 38cm coaligned telescopes, one for the FUV channel (130-180nm) and
the other for the NUV (200-300nm) and VIS (320-550nm) channels, with a field of
view of 28 . The FUV and the NUV detectors are operated in the high
gain photon counting mode whereas the VIS detector is operated in the low gain
integration mode. The FUV and NUV channels have filters and gratings, whereas
the VIS channel has filters. The ASTROSAT was launched on 28th September 2015.
The performance verification of UVIT was carried out after the opening of the
UVIT doors on 30th November 2015, till the end of March 2016 within the
allotted time of 50 days for calibration. All the on-board systems were found
to be working satisfactorily. During the PV phase, the UVIT observed several
calibration sources to characterise the instrument and a few objects to
demonstrate the capability of the UVIT. The resolution of the UVIT was found to
be about 1.4 - 1.7 in the FUV and NUV. The sensitivity in various
filters were calibrated using standard stars (white dwarfs), to estimate the
zero-point magnitudes as well as the flux conversion factor. The gratings were
also calibrated to estimate their resolution as well as effective area. The
sensitivity of the filters were found to be reduced up to 15\% with respect to
the ground calibrations. The sensitivity variation is monitored on a monthly
basis. UVIT is all set to roll out science results with its imaging capability
with good resolution and large field of view, capability to sample the UV
spectral region using different filters and capability to perform variability
studies in the UV.Comment: 10 pages, To appear in SPIE conference proceedings, SPIE conference
paper, 201
Molecular Docking and Dynamics Simulation of Natural Compounds from Betel Leaves (<em>Piper betle</em> L.) for Investigating the Potential Inhibition of Alpha-Amylase and Alpha-Glucosidase of Type 2 Diabetes
Piper betle L. is widely distributed and commonly used medicinally important herb. It can also be used as a medication for type 2 diabetes patients. In this study, compounds of P. betle were screened to investigate the inhibitory action of alpha-amylase and alpha-glucosidase against type 2 diabetes through molecular docking, molecular dynamics simulation, and ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis. The molecule apigenin-7-O-glucoside showed the highest binding affinity among 123 (one hundred twenty-three) tested compounds. This compound simultaneously bound with the two-target proteins alpha-amylase and alpha-glucosidase, with high molecular mechanics-generalized born surface area (MM/GBSA) values (ÎG Bind = â45.02 kcal molâ1 for alpha-amylase and â38.288 for alpha-glucosidase) compared with control inhibitor acarbose, which had binding affinities of â36.796 kcal molâ1 for alpha-amylase and â29.622 kcal molâ1 for alpha-glucosidase. The apigenin-7-O-glucoside was revealed to be the most stable molecule with the highest binding free energy through molecular dynamics simulation, indicating that it could compete with the inhibitorsâ native ligand. Based on ADMET analysis, this phytochemical exhibited a wide range of physicochemical, pharmacokinetic, and drug-like qualities and had no significant side effects, making them prospective drug candidates for type 2 diabetes. Additional in vitro, in vivo, and clinical investigations are needed to determine the precise efficacy of drugs
Search for intermediate-mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo
International audienceIntermediate-mass black holes (IMBHs) span the approximate mass range 100â105âMâ, between black holes (BHs) that formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass âŒ150âMâ providing direct evidence of IMBH formation. Here, we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modeled (matched filter) and model-independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass 200âMâ and effective aligned spin 0.8 at 0.056 Gpcâ3 yrâ1 (90% confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to 0.08 Gpcâ3 yrâ1.Key words: gravitational waves / stars: black holes / black hole physicsCorresponding author: W. Del Pozzo, e-mail: [email protected]â Deceased, August 2020