835 research outputs found
Dynamic Modeling and Control System Design for Shape Memory Alloy Actuators
Shape memory alloy (SMA) is a type of smart material which remembers its original state. It is light weight and small, and known to provide high contraction force with low noise. Its application has wide range from robotics to medical science. One of its potential applications in space is a supporting system of membrane structure that can be used as synthetic aperture radar (SAR) antenna to achieve high flatness. It exhibits nonlinear phenomena called hysteresis when it's electrically heated. Hysteresis is a nonlinear phenomenon that refers to the dependence of a physical system on the environment. Hysteresis in SMA causes a major difficulty in control system design. Un-modeled or poorly modeled hysteresis introduces inaccuracy in tracking and the performance of the system. Experimental test bench is constructed for one set of SMA actuators that resembles the membrane structure's supporting system. Hysteresis is obtained by running open loop test with the test bench. Dynamic model of the SMA wires is developed using classical Preisach model and modified Maxwell model. Then the inverse model is implemented in feed-forward loop to compensate for nonlinear hysteresis. Simple feedback controllers are added to correct the modeling errors. Experimental results reveal that the error is significantly reduced when comparing feedback controller with hybrid feedback and feed-forward controller
Domain Reduction Strategy for Non Line of Sight Imaging
This paper presents a novel optimization-based method for non-line-of-sight
(NLOS) imaging that aims to reconstruct hidden scenes under various setups. Our
method is built upon the observation that photons returning from each point in
hidden volumes can be independently computed if the interactions between hidden
surfaces are trivially ignored. We model the generalized light propagation
function to accurately represent the transients as a linear combination of
these functions. Moreover, our proposed method includes a domain reduction
procedure to exclude empty areas of the hidden volumes from the set of
propagation functions, thereby improving computational efficiency of the
optimization. We demonstrate the effectiveness of the method in various NLOS
scenarios, including non-planar relay wall, sparse scanning patterns, confocal
and non-confocal, and surface geometry reconstruction. Experiments conducted on
both synthetic and real-world data clearly support the superiority and the
efficiency of the proposed method in general NLOS scenarios
Thiol-linked peroxidase activity of human ceruloplasmin
AbstractHuman ceruloplasmin exhibited different antioxidant effects according to the electron donors in a metal-catalyzed oxidation system. Purified ceruloplasmin did not play a significant role in the protection of DNA strand breaks in the ascorbate/Fe3+/O2 system. However, when ascorbates were replaced with a thiol-reducing equivalent such as dithiothreitol, DNA strand breaks were significantly prevented by the same amount of ceruloplasmin. Ceruloplasmin did not catalyze the decomposition of H2O2 in the absence of reduced glutathione. On the contrary, ceruloplasmin showed a potent peroxidase ability to destroy H2O2 in the presence of reduced glutathione. In conclusion, the removal of H2O2 by human ceruloplasmin is not simply stoichiometric but thiol-dependent
EPINET: A Fully-Convolutional Neural Network Using Epipolar Geometry for Depth from Light Field Images
Light field cameras capture both the spatial and the angular properties of
light rays in space. Due to its property, one can compute the depth from light
fields in uncontrolled lighting environments, which is a big advantage over
active sensing devices. Depth computed from light fields can be used for many
applications including 3D modelling and refocusing. However, light field images
from hand-held cameras have very narrow baselines with noise, making the depth
estimation difficult. any approaches have been proposed to overcome these
limitations for the light field depth estimation, but there is a clear
trade-off between the accuracy and the speed in these methods. In this paper,
we introduce a fast and accurate light field depth estimation method based on a
fully-convolutional neural network. Our network is designed by considering the
light field geometry and we also overcome the lack of training data by
proposing light field specific data augmentation methods. We achieved the top
rank in the HCI 4D Light Field Benchmark on most metrics, and we also
demonstrate the effectiveness of the proposed method on real-world light-field
images.Comment: Accepted to CVPR 2018, Total 10 page
Attribution of the 2015 record high sea surface temperatures over the central equatorial Pacific and tropical Indian Ocean
This study assessed the anthropogenic contribution to the 2015 record-breaking high sea surface temperatures (SSTs) observed in the central equatorial Pacific and tropical Indian Ocean. Considering a close link between extreme warm events in these regions, we conducted a joint attribution analysis using a fraction of attributable risk approach. Probability of occurrence of such extreme anomalies and long-term trends for the two oceanic regions were compared between CMIP5 multi-model simulations with and without anthropogenic forcing. Results show that the excessive warming in both regions is well beyond the range of natural variability and robustly attributable to human activities due to greenhouse gas increase. We further explored associated mechanisms including the Bjerknes feedback and background anthropogenic warming. It is concluded that background warming was the main contribution to the 2015 extreme SST event over the central equatorial Pacific Ocean on a developing El Niño condition, which in turn induced the extreme SST event over the tropical Indian Ocean through the atmospheric bridge effect.113Ysciescopu
The Alzheimer's Disease-Associated R47H Variant of TREM2 Has an Altered Glycosylation Pattern and Protein Stability
Pure Sensory Deficit at the T4 Sensory Level as an Isolated Manifestation of Lateral Medullary Infarction
In rare cases restricted sensory deficits along the somatotopic topography of the spinothalamic tract can develop from a lateral medullary infarction. To our knowledge, isolated dermatomal sensory deficit as a single manifestation of a lateral medullary infarction has not been reported previously. A 58-year-old man presenting with sudden left-sided paresthesia complained of sensory deficit of pain and temperature below the left T4 sensory level without other neurologic deficits. Diffuse- and T2-weighted magnetic resonance imaging (MRI) of the brain showed high signal intensities in the right lower medulla oblongata, whereas thoracic-spine MRI and somatosensory evoked potentials produced normal findings
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