11 research outputs found
Localization Uncertainty Estimation for Anchor-Free Object Detection
Since many safety-critical systems, such as surgical robots and autonomous
driving cars, are in unstable environments with sensor noise and incomplete
data, it is desirable for object detectors to take into account the confidence
of localization prediction. There are three limitations of the prior
uncertainty estimation methods for anchor-based object detection. 1) They model
the uncertainty based on object properties having different characteristics,
such as location (center point) and scale (width, height). 2) they model a box
offset and ground-truth as Gaussian distribution and Dirac delta distribution,
which leads to the model misspecification problem. Because the Dirac delta
distribution is not exactly represented as Gaussian, i.e., for any and
. 3) Since anchor-based methods are sensitive to hyper-parameters of
anchor, the localization uncertainty modeling is also sensitive to these
parameters. Therefore, we propose a new localization uncertainty estimation
method called Gaussian-FCOS for anchor-free object detection. Our method
captures the uncertainty based on four directions of box offsets~(left, right,
top, bottom) that have similar properties, which enables to capture which
direction is uncertain and provide a quantitative value in range~[0, 1]. To
this end, we design a new uncertainty loss, negative power log-likelihood loss,
to measure uncertainty by weighting IoU to the likelihood loss, which
alleviates the model misspecification problem. Experiments on COCO datasets
demonstrate that our Gaussian-FCOS reduces false positives and finds more
missing-objects by mitigating over-confidence scores with the estimated
uncertainty. We hope Gaussian-FCOS serves as a crucial component for the
reliability-required task
Edge-carboxylated graphene nanoplatelets as oxygen-rich metal-free cathodes for organic dye-sensitized solar cells
Edge-carboxylated graphene nanoplatelets (ECGnPs) were synthesized by the simple, efficient and eco-friendly ball-milling of graphite in the presence of dry ice and used as oxygen-rich metal-free counter electrodes (CEs) in organic dye-sensitized solar cells (DSSCs), for the first time. The resultant ECGnPs are soluble in many polar solvents including 2-propanol due to the polar nature of numerous carboxylic acids at edges, allowing an electrostatic spray (e-spray) to be deposited on fluorine-doped SnO2 (FTO)/glass substrates. The ECGnP-CE exhibited profound improvements in the electrochemical stability for the Co(bpy)3 2+/3+ redox couple compared to the platinum (Pt)-CE. The charge transfer resistance (RCT), related to the interface between an electrolyte and a CE, was significantly reduced to 0.87 ?? cm2, much lower than those of (Pt)-CE (2.19 ?? cm 2), PEDOT:PSS-CE (2.63 ?? cm2) and reduced graphene oxide (rGO)-CE (1.21 ?? cm2). The DSSC based on the JK-303-sensitizer and ECGnP-CE displayed a higher photovoltaic performance (FF, Jsc, and ??, 74.4%, 14.07 mA cm-2 and 9.31%) than those with the Pt-CE (71.6%, 13.69 mA cm-2 and 8.67%), PEDOT:PSS (68.7%, 13.68 mA cm-2 and 8.25%) and rGO-CE (72.9%, 13.88 mA cm-2 and 8.94%).close3
Stochastic fluctuation and transport of tokamak edge plasmas with the resonant magnetic perturbation field
We present that a statistical method known as the complexity-entropy analysis is useful to characterize a state of plasma turbulence and flux in the resonant magnetic perturbation (RMP) edge localized mode (ELM) control experiment. The stochastic pedestal top temperature fluctuation in the RMP ELM suppression phase is distinguished from the chaotic fluctuation in the natural ELM-free phase. It is discussed that the stochastic temperature fluctuation can be originated from the narrow layer of the field penetration on the pedestal top. The forced magnetic island can emit the resonant drift wave of comparable sizes (relatively low-k) in the RMP ELM suppression phase, and it can result in the generation of stochastic higher wavenumber fluctuations coupled to tangled fields around the island. The analysis of the ion saturation current measurement around the major outer striking point on the divertor shows that it also becomes more stochastic as the stronger plasma response to the RMP field is expected. © 2022 Author(s).11Nsciescopu
Stochastic fluctuation and transport of tokamak edge plasmas with the resonant magnetic perturbation field
We present that a statistical method known as the complexity???entropy analysis is useful to characterize a state of plasma turbulence and flux in the resonant magnetic perturbation (RMP) edge localized mode (ELM) control experiment. The stochastic pedestal top temperature fluctuation in the RMP ELM suppression phase is distinguished from the chaotic fluctuation in the natural ELM-free phase. It is discussed that the stochastic temperature fluctuation can be originated from the narrow layer of the field penetration on the pedestal top. The forced magnetic island can emit the resonant drift wave of comparable sizes (relatively low-k) in the RMP ELM suppression phase, and it can result in the generation of stochastic higher wavenumber fluctuations coupled to tangled fields around the island. The analysis of the ion saturation current measurement around the major outer striking point on the divertor shows that it also becomes more stochastic as the stronger plasma response to the RMP field is expected.
I. INTRODUCTIO