508 research outputs found
Polarization Beam Splitter Based on Self-Collimation of a Hybrid Photonic Crystal
A photonic crystal polarization beam splitter based on photonic band gap and self-collimation effects is designed for optical communication wavelengths. The photonic crystal structure consists of a polarization-insensitive self-collimation region and a splitting region. TM- and TE-polarized waves propagate without diffraction in the self-collimation region, whereas they split by 90 degrees in the splitting region. Efficiency of more than 75% for TM- and TE-polarized light is obtained for a polarization beam splitter size of only 17 ÎĽm x 17 ÎĽm in a wavelength interval of 60 nm including 1.55 ÎĽm
Deep Multi-Modal Classification of Intraductal Papillary Mucinous Neoplasms (IPMN) with Canonical Correlation Analysis
Pancreatic cancer has the poorest prognosis among all cancer types.
Intraductal Papillary Mucinous Neoplasms (IPMNs) are radiographically
identifiable precursors to pancreatic cancer; hence, early detection and
precise risk assessment of IPMN are vital. In this work, we propose a
Convolutional Neural Network (CNN) based computer aided diagnosis (CAD) system
to perform IPMN diagnosis and risk assessment by utilizing multi-modal MRI. In
our proposed approach, we use minimum and maximum intensity projections to ease
the annotation variations among different slices and type of MRIs. Then, we
present a CNN to obtain deep feature representation corresponding to each MRI
modality (T1-weighted and T2-weighted). At the final step, we employ canonical
correlation analysis (CCA) to perform a fusion operation at the feature level,
leading to discriminative canonical correlation features. Extracted features
are used for classification. Our results indicate significant improvements over
other potential approaches to solve this important problem. The proposed
approach doesn't require explicit sample balancing in cases of imbalance
between positive and negative examples. To the best of our knowledge, our study
is the first to automatically diagnose IPMN using multi-modal MRI.Comment: Accepted for publication in IEEE International Symposium on
Biomedical Imaging (ISBI) 201
Moving object detection using adaptive subband decomposition and fractional lower order statistics in video sequences
Cataloged from PDF version of article.In this paper, a moving object detection method in video sequences is described. In the 3rst step, the camera motion is
eliminated using motion compensation. An adaptive subband decomposition structure is then used to analyze the motion
compensated image. In the “low–high” and “high–low” subimages moving objects appear as outliers and they are detected
using a statistical detection test based on fractional lower-order statistics. It turns out that the distribution of the subimage
pixels is almost Gaussian in general. On the other hand, at the object boundaries the distribution of the pixels in the subimages
deviates from Gaussianity due to the existence of outliers. By detecting the regions containing outliers the boundaries of the
moving objects are estimated. Simulation examples are presented.
(C) 2002 Elsevier Science B.V. All rights reserved
Sustainable manufacturing of new construction material from alkali activation of volcanic tuff
The current climate emergency leads to reduction of virgin raw material extraction and promotes circular economy. In this framework, alkali activation of unemployed fraction of grey tuff, combined with glass waste, provides a range of sustainable construction materials. For the sake of sustainability, tuff powder was subjected to rapid attack (30 min), operated by a 'weak' alkaline solution (3 M NaOH), and then left to dry at low temperature (75 degrees C) for 72 h. The addition of Triton X-100 surfactant was considered to obtain foams starting from slurries with different liquid-to-solid ratio. A thermal treatment was applied to selected samples, at low temperature (700 degrees C). Despite the 'mild' activation conditions, all products survived after immersion in boiling water or acid solution, already in the unfired state, according to the formation of a multiphasic gel. The strength-to density ratio, especially for foams, in both unfired and fired form, compares well with that of already existing construction materials (e.g. it could exceed 5 MPa cm3/g)
Optoelectronic cooling of mechanical modes in a semiconductor nanomembrane
Optical cavity cooling of mechanical resonators has recently become a
research frontier. The cooling has been realized with a metal-coated silicon
microlever via photo-thermal force and subsequently with dielectric objects via
radiation pressure. Here we report cavity cooling with a crystalline
semiconductor membrane via a new mechanism, in which the cooling force arises
from the interaction between the photo-induced electron-hole pairs and the
mechanical modes through the deformation potential coupling. The optoelectronic
mechanism is so efficient as to cool a mode down to 4 K from room temperature
with just 50 uW of light and a cavity with a finesse of 10 consisting of a
standard mirror and the sub-wavelength-thick semiconductor membrane itself. The
laser-cooled narrow-band phonon bath realized with semiconductor mechanical
resonators may open up a new avenue for photonics and spintronics devices.Comment: 5 pages, 4 figure
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