533 research outputs found
Design of Ultrafast All-Optical Pseudo Binary Random Sequence Generator, 4-bit Multiplier and Divider using 2 x 2 Silicon Micro-ring Resonators
All-optical devices are essential for next generation ultrafast,
ultralow-power and ultrahigh bandwidth information processing systems. Silicon
microring resonators (SiMRR) provide a versatile platform for all-optical
switching and CMOS-compatible computing, with added advantages of high
Q-factor, tunability, compactness, cascadability and scalability. A detailed
theoretical analysis of ultrafast all-optical switching 2 x 2 SiMRRs has been
carried out incorporating the effects of two photon absorption induced
free-carrier injection and thermo optic effect. The results have been used to
design simple and compact all-optical 3-bit and 4-bit pseudo-random binary
sequence generators and the first reported designs of all-optical 4 x 4-bit
multiplier and divider. The designs have been optimized for low-power,
ultrafast operation with high modulation depth, enabling logic operations at 45
Gbps.Comment: 13 pages, 4 figures. Submitted at Journal (Optik) for publicatio
Schr\"odinger Spectrum based Continuous Cuff-less Blood Pressure Estimation using Clinically Relevant Features from PPG Signal and its Second Derivative
The presented study aims to estimate blood pressure (BP) using
photoplethysmogram (PPG) signals while employing multiple machine learning
models. The study proposes a novel algorithm for signal reconstruction, which
utilizes the semi-classical signal analysis (SCSA) technique. The proposed
algorithm optimises the semi-classical constant and eliminates the trade-off
between complexity and accuracy in reconstruction. The reconstructed signals'
spectral features are extracted and incorporated with clinically relevant PPG
and its second derivative's (SDPPG) morphological features. The developed
method was assessed using a publicly available virtual in-silico dataset with
more than 4000 subjects, and the Multi-Parameter Intelligent Monitoring in
Intensive Care Units dataset. Results showed that the method attained a mean
absolute error of 5.37 and 2.96 mmHg for systolic and diastolic BP,
respectively, using the CatBoost supervisory algorithm. This approach met the
standards set by the Advancement of Medical Instrumentation, and achieved Grade
A for all BP categories in the British Hypertension Society protocol. The
proposed framework performs well even when applied to a combined database of
the MIMIC-III and the Queensland dataset. This study also evaluates the
proposed method's performance in a non-clinical setting with noisy and deformed
PPG signals, to validate the efficacy of the SCSA method. The noise stress
tests showed that the algorithm maintained its key feature detection, signal
reconstruction capability, and estimation accuracy up to a 10 dB SNR ratio. It
is believed that the proposed cuff-less BP estimation technique has the
potential to perform well on resource-constrained settings due to its
straightforward implementation approach.Comment: 16 pages, 8 figures, 8 tables, submitted to Biomedical Signal
Processing and Control, Elsevie
Galactic molecular clouds as sources of secondary positrons
Secondary positrons produced inside Galactic Molecular Clouds (GMCs) can
significantly contribute to the observed positron spectrum on Earth.
Multi-wavelength data of GMCs are particularly useful in building this model. A
very recent survey implemented the optical/IR dust extinction measurements to
trace 567 GMCs within 4 kpc of Earth, residing in the Galactic plane. We use
the updated catalog of GMCs reported in recent papers, distributed in the
Galactic plane, to find the secondary positrons produced in them in
interactions of cosmic rays with molecular hydrogen. Moreover, by analyzing the
\textit{Fermi}-LAT data, new GMCs have been discovered near the Galactic plane.
We also include some of these GMCs closest to the Earth, where cosmic ray
interactions produce secondaries. It has been speculated earlier that cosmic
rays may be reaccelerated in some GMCs. We select 7 GMCs out of 567 GMCs
recently reported, within 4 kpc of Earth, where reacceleration due to
magnetized turbulence is assumed. We include a hardened component of secondary
positrons produced from the interaction of reaccelerated CRs in those 7 GMCs.
We use publicly available code \texttt{DRAGON} for our simulation setup to
study CR propagation in the Galaxy and show that the observed positron spectrum
can be well explained in the energy range of 1 to 1000 GeV by our
self-consistent model.Comment: Proceedings of the 37th International Cosmic Ray Conference (ICRC
2021
- …