20 research outputs found
A Novel Loss Function Utilizing Wasserstein Distance to Reduce Subject-Dependent Noise for Generalizable Models in Affective Computing
Emotions are an essential part of human behavior that can impact thinking,
decision-making, and communication skills. Thus, the ability to accurately
monitor and identify emotions can be useful in many human-centered applications
such as behavioral training, tracking emotional well-being, and development of
human-computer interfaces. The correlation between patterns in physiological
data and affective states has allowed for the utilization of deep learning
techniques which can accurately detect the affective states of a person.
However, the generalisability of existing models is often limited by the
subject-dependent noise in the physiological data due to variations in a
subject's reactions to stimuli. Hence, we propose a novel cost function that
employs Optimal Transport Theory, specifically Wasserstein Distance, to scale
the importance of subject-dependent data such that higher importance is
assigned to patterns in data that are common across all participants while
decreasing the importance of patterns that result from subject-dependent noise.
The performance of the proposed cost function is demonstrated through an
autoencoder with a multi-class classifier attached to the latent space and
trained simultaneously to detect different affective states. An autoencoder
with a state-of-the-art loss function i.e., Mean Squared Error, is used as a
baseline for comparison with our model across four different commonly used
datasets. Centroid and minimum distance between different classes are used as a
metrics to indicate the separation between different classes in the latent
space. An average increase of 14.75% and 17.75% (from benchmark to proposed
loss function) was found for minimum and centroid euclidean distance
respectively over all datasets.Comment: 9 page
Redefining Super-Resolution: Fine-mesh PDE predictions without classical simulations
In Computational Fluid Dynamics (CFD), coarse mesh simulations offer
computational efficiency but often lack precision. Applying conventional
super-resolution to these simulations poses a significant challenge due to the
fundamental contrast between downsampling high-resolution images and
authentically emulating low-resolution physics. The former method conserves
more of the underlying physics, surpassing the usual constraints of real-world
scenarios. We propose a novel definition of super-resolution tailored for
PDE-based problems. Instead of simply downsampling from a high-resolution
dataset, we use coarse-grid simulated data as our input and predict fine-grid
simulated outcomes. Employing a physics-infused UNet upscaling method, we
demonstrate its efficacy across various 2D-CFD problems such as discontinuity
detection in Burger's equation, Methane combustion, and fouling in Industrial
heat exchangers. Our method enables the generation of fine-mesh solutions
bypassing traditional simulation, ensuring considerable computational saving
and fidelity to the original ground truth outcomes. Through diverse boundary
conditions during training, we further establish the robustness of our method,
paving the way for its broad applications in engineering and scientific CFD
solvers.Comment: Accepted at Machine Learning and the Physical Sciences Workshop,
NeurIPS 202
Ultrafast Green Single Photon Emission from an InGaN Quantum Dot-in-a-GaN Nanowire at Room Temperature
In recent years, there has been a growing demand for room-temperature visible
single-photon emission from InGaN nanowire-quantum-dots (NWQDs) due to its
potential in developing quantum computing, sensing, and communication
technologies. Despite various approaches explored for growing InGaN quantum
dots on top of nanowires (NWs), achieving the emission of a single photon at
room temperature with sensible efficiency remains a challenge. This challenge
is primarily attributed to difficulties in accomplishing the radial confinement
limit and the inherent giant built-in potential of the NWQD. In this report, we
have employed a novel Plasma Assisted Molecular Beam Epitaxy (PAMBE) growth
approach to reduce the diameter of the QD to the excitonic Bohr radius of
InGaN, thereby achieving strong lateral confinement. Additionally, we have
successfully suppressed the strong built-in potential by reducing the QD
diameter. Toward the end of the report, we have demonstrated single-photon
emission ( = 561 nm) at room-temperature from the NWQD and measured
the second-order correlation function as 0.11, which is notably low
compared to other reported findings. Furthermore, the lifetime of carriers in
the QD is determined to be 775 ps, inferring a high operational speed of the
devices
Investigation of Magnesium Silicate as an Effective Gate Dielectric for AlGaN/GaN Metal Oxide High Electron Mobility Transistors (MOSHEMT)
In this study, a 6 nm layer of Magnesium Silicate (Mg-Silicate) was deposited
on AlGaN/GaN heterostructure by sputtering of multiple stacks of MgO and
SiO, followed by rapid thermal annealing in a nitrogen (N)
environment. The X-ray photoelectron spectroscopy (XPS) analysis confirmed the
stoichiometric Mg-Silicate (MgSiO) after being annealed at a temperature
of 850 C for 70 seconds. Atomic force microscopy (AFM) was employed to
measure the root mean square (RMS) roughness (2.20 nm) of the Mg-Silicate. A
significant reduction in reverse leakage current, by a factor of three orders
of magnitude, was noted for the Mg-Silicate/AlGaN/GaN metal-oxide-semiconductor
(MOS) diode in comparison to the Schottky diode. The dielectric constant of
Mg-Silicate() and the interface density of states
(D) with AlGaN were approximated at 6.6 and 2.0
10 cmeV respectively, utilizing capacitance-voltage (CV)
characteristics