265 research outputs found
A Fault-Tolerant Emergency-Aware Access Control Scheme for Cyber-Physical Systems
Access control is an issue of paramount importance in cyber-physical systems
(CPS). In this paper, an access control scheme, namely FEAC, is presented for
CPS. FEAC can not only provide the ability to control access to data in normal
situations, but also adaptively assign emergency-role and permissions to
specific subjects and inform subjects without explicit access requests to
handle emergency situations in a proactive manner. In FEAC, emergency-group and
emergency-dependency are introduced. Emergencies are processed in sequence
within the group and in parallel among groups. A priority and dependency model
called PD-AGM is used to select optimal response-action execution path aiming
to eliminate all emergencies that occurred within the system. Fault-tolerant
access control polices are used to address failure in emergency management. A
case study of the hospital medical care application shows the effectiveness of
FEAC
DeepICP: An End-to-End Deep Neural Network for 3D Point Cloud Registration
We present DeepICP - a novel end-to-end learning-based 3D point cloud
registration framework that achieves comparable registration accuracy to prior
state-of-the-art geometric methods. Different from other keypoint based methods
where a RANSAC procedure is usually needed, we implement the use of various
deep neural network structures to establish an end-to-end trainable network.
Our keypoint detector is trained through this end-to-end structure and enables
the system to avoid the inference of dynamic objects, leverages the help of
sufficiently salient features on stationary objects, and as a result, achieves
high robustness. Rather than searching the corresponding points among existing
points, the key contribution is that we innovatively generate them based on
learned matching probabilities among a group of candidates, which can boost the
registration accuracy. Our loss function incorporates both the local similarity
and the global geometric constraints to ensure all above network designs can
converge towards the right direction. We comprehensively validate the
effectiveness of our approach using both the KITTI dataset and the
Apollo-SouthBay dataset. Results demonstrate that our method achieves
comparable or better performance than the state-of-the-art geometry-based
methods. Detailed ablation and visualization analysis are included to further
illustrate the behavior and insights of our network. The low registration error
and high robustness of our method makes it attractive for substantial
applications relying on the point cloud registration task.Comment: 10 pages, 6 figures, 3 tables, typos corrected, experimental results
updated, accepted by ICCV 201
Plasmonic nano-resonator enhanced one-photon luminescence from single gold nanorods
Strong Stokes and anti-Stokes one-photon luminescence from single gold
nanorods is measured in experiments. It is found that the intensity and
polarization of the Stokes and anti-Stokes emissions are in strong correlation.
Our experimental observation discovered a coherent process in light emission
from single gold nanorods. We present a theoretical mode, based on the concept
of cavity resonance, for consistently understanding both Stokes and anti-Stokes
photoluminescence. Our theory is in good agreement of all our measurements.Comment: 14 pages, 7 figures, 2 table
Environmental correlates of sedentary behaviors and physical activity in Chinese preschool children:A cross-sectional study
Objective: This cross-sectional study examined environmental correlates of sedentary behavior (SB) and physical activity (PA) in preschool children in the urban area of Tianjin, China. Methods: Data were collected from the Physical Activity and Health in Tianjin Chinese Children study, involving healthy children 3â6 years old and their families. In all children (n = 980), leisure-time SB (LTSB) and leisure-time PA (LTPA) were reported in min/day by parents. In a subgroup (n = 134), overall sedentary time, light PA, and moderate-to-vigorous PA (MVPA) were objectively measured using ActiGraph accelerometry (âĽ3 days, âĽ10 h/day). Environmental correlates were collected using a questionnaire that included home and neighborhood characteristics (e.g., traffic safety, presence of physical activity facilities) and children's behaviors. Potential correlates were identified using linear regression analysis. Results: Multiple linear regression analysis showed that âhaving grandparents as primary caregiversâ (βs and 95% confidence intervals (95%CIs) for overall sedentary time: 29.7 (2.1â57.2); LTSB (ln): 0.19 (0.11â0.28)) and âhaving a television (for LTSB (ln): 0.13 (0.00â0.25)) or computer (for LTSB (ln): 0.13 (0.03â0.23)) in the child's bedroomâ were both associated with higher SB. Furthermore, âhaving grandparents as primary caregiversâ was associated with less MVPA (β (95%CI): â7.6 (â14.1 to â1.2)), and âactive commuting to school by walkingâ correlated with more MVPA (β (95%CI): 9.8 (2.2â17.4)). The path model showed that âmore neighborhood PA facilities close to homeâ was indirectly related to higher LTPA (ln), which was partly mediated by âoutdoor playâ (path coefficients (95%CI): 0.005 (0.002â0.008)) and âgoing to these facilities more oftenâ (path coefficients (95%CI): 0.013 (0.008â0.018)). Traffic safety was not a correlate. Conclusion: Family structure and media exposure in the home maybe important factors in shaping preschoolersâ PA patterns. Built environmental correlates could indirectly influence preschoolersâ LTPA through parental help with engaging in active behaviors
Directional Enhanced Probe for Side-Illumination Tip Enhanced Spectroscopy
We demonstrate a high-performance apertureless near-field probe made of a
tapered metal tip with a set of periodic shallow grooves near the apex. The
spontaneous emission from a single emitter near the tip is investigated
systematically for the side-illumination tip enhanced spectroscopy (TES). In
contrast with the bare tapered metal tip in conventional side-illumination TES,
the corrugated probe not only enhances strongly local excitation field but also
concentrates the emission directivity, which leads to high collection
efficiency and signal-to-noise ratio. In particular, we propose an asymmetric
TES tip based on two coupling nanorods with different length at the apex to
realize unidirectional enhanced emission rate from a single emitter.
Interestingly, we find that the radiation pattern is sensitive to the emission
wavelength and the emitter positions respective to the apex, which can result
in an increase of signal-to-noise ratio by suppressing undesired signal. The
proposed asymmetrical corrugated probe opens up a broad range of practical
applications, e.g. increasing the detection efficiency of tip enhanced
spectroscopy at the single-molecule level
Nonlinear Analysis of Dynamic Stability and the Prediction of Wing Rock
Nonlinear analysis of dynamic stability for a delta wing in rolling motion at high angles of attack is presented based on a modeled differential equation for wing rolling motion. A method for determining the aerodynamic coef cients up to third-order approximation in the modeled equation, which are functions of the amplitude of wing rolling oscillation at a xed high angle of attack, is proposed by use of the Fourier expansion approach. Using the modeled equations of motion combined with the aerodynamic coef cients determined by the conical Eulerian computations of supersonic ow past a forced rolling delta wing, we predicted the rock motion of a delta wing that was set into a free-to-roll motion. The results were compared with those obtained by direct coupling calculations based on solving the unsteady ow equations and the wing motion equations simultaneously, which proved to be in fairly good agreement with each other. A numerical investigation of active control technique of the wing rock was also performed by use of the present method
Hybrid Metal-Dielectric Plasmonic Zero Mode Waveguide for Enhanced Single Molecule Detection
We fabricated hybrid metal-dielectric nanoantennas and measured their optical
response at three different wavelengths. The nanostructure is fabricated on a
bilayer film formed by the sequential deposition of silicon and gold on a
transparent substrate. The optical characterization is done via fluorescence
measurements. We characterized the fluorescence enhancement, as well as the
lifetime and detection volume reduction for each wavelength. We observe that
the hybrid metal-dielectric nanoantennas behave as enhanced Zero Mode
Waveguides in the near-infrared spectral region. Their detection volume is such
that they can perform enhanced single-molecule detection at tens of microM.
However, a wavelength blue-shift of 40 nm dramatically decreases the
performance of the nanoantennas. We compared their behavior with that of a
golden ZMW, and we verified that the dielectric silicon layer improves the
design. We interpreted the experimental observations with the help of numerical
simulations. In addition, the simulations showed that the field enhancement of
the structure highly depends on the incoming beam: tightly focused beams yield
lower field enhancements than plane-waves
- âŚ