151,599 research outputs found
Experimental Assessment of ‘subgrid’ scale Probability Density Function Models for Large Eddy Simulation
Filtered density functions (FDFs) of mixture fraction are quantified by analyzing
experimental data obtained from two-dimensional planar laser-induced fluorescence scalar
measurements in the isothermal swirling flow of a combustor operating at a Reynolds number of
28,662 for three different swirl numbers (0.3, 0.58 and 1.07). Two-dimensional filtering using a
box filter was performed on the measured scalar to obtain the filtered variables used for
presumed FDF for Large Eddy Simulations (LES). A dependant variable
from the measured scalar, which was a pre-computed temperature, was integrated over the
experimentally obtained FDF as well as over the presumed beta or top-hat FDFs and a relative
error in temperature prediction was calculated. The experimentally measured FDFs depended on
swirl numbers and axial and radial positions in the flow. The FDFs were unimodal in the regions
of low variance and bimodal in the regions of high variance. The influence of the filter spatial dimension on the measured FDF was evaluated and consequences for subgrid modeling for LES discussed
Guided Filtering based Pyramidal Stereo Matching for Unrectified Images
Stereo matching deals with recovering quantitative
depth information from a set of input images, based on the visual
disparity between corresponding points. Generally most of the
algorithms assume that the processed images are rectified. As
robotics becomes popular, conducting stereo matching in the
context of cloth manipulation, such as obtaining the disparity
map of the garments from the two cameras of the cloth folding
robot, is useful and challenging. This is resulted from the fact of
the high efficiency, accuracy and low memory requirement under
the usage of high resolution images in order to capture the details
(e.g. cloth wrinkles) for the given application (e.g. cloth folding).
Meanwhile, the images can be unrectified. Therefore, we propose
to adapt guided filtering algorithm into the pyramidical stereo
matching framework that works directly for unrectified images.
To evaluate the proposed unrectified stereo matching in terms of
accuracy, we present three datasets that are suited to especially
the characteristics of the task of cloth manipulations. By com-
paring the proposed algorithm with two baseline algorithms on
those three datasets, we demonstrate that our proposed approach
is accurate, efficient and requires low memory. This also shows
that rather than relying on image rectification, directly applying
stereo matching through the unrectified images can be also quite
effective and meanwhile efficien
OMCat: Catalogue of Serendipitous Sources Detected with the XMM-Newton Optical Monitor
The Optical Monitor Catalogue of serendipitous sources (OMCat) contains
entries for every source detected in the publicly available XMM-Newton Optical
Monitor (OM) images taken in either the imaging or ``fast'' modes. Since the OM
is coaligned and records data simultaneously with the X-ray telescopes on
XMM-Newton, it typically produces images in one or more near-UV/optical bands
for every pointing of the observatory. As of the beginning of 2006, the public
archive had covered roughly 0.5% of the sky in 2950 fields.
The OMCat is not dominated by sources previously undetected at other
wavelengths; the bulk of objects have optical counterparts. However, the OMCat
can be used to extend optical or X-ray spectral energy distributions for known
objects into the ultraviolet, to study at higher angular resolution objects
detected with GALEX, or to find high-Galactic-latitude objects of interest for
UV spectroscopy.Comment: 25 pages, 22 figures, submitted to PAS
Deformable Part Models are Convolutional Neural Networks
Deformable part models (DPMs) and convolutional neural networks (CNNs) are
two widely used tools for visual recognition. They are typically viewed as
distinct approaches: DPMs are graphical models (Markov random fields), while
CNNs are "black-box" non-linear classifiers. In this paper, we show that a DPM
can be formulated as a CNN, thus providing a novel synthesis of the two ideas.
Our construction involves unrolling the DPM inference algorithm and mapping
each step to an equivalent (and at times novel) CNN layer. From this
perspective, it becomes natural to replace the standard image features used in
DPM with a learned feature extractor. We call the resulting model DeepPyramid
DPM and experimentally validate it on PASCAL VOC. DeepPyramid DPM significantly
outperforms DPMs based on histograms of oriented gradients features (HOG) and
slightly outperforms a comparable version of the recently introduced R-CNN
detection system, while running an order of magnitude faster
A Deep Pyramid Deformable Part Model for Face Detection
We present a face detection algorithm based on Deformable Part Models and
deep pyramidal features. The proposed method called DP2MFD is able to detect
faces of various sizes and poses in unconstrained conditions. It reduces the
gap in training and testing of DPM on deep features by adding a normalization
layer to the deep convolutional neural network (CNN). Extensive experiments on
four publicly available unconstrained face detection datasets show that our
method is able to capture the meaningful structure of faces and performs
significantly better than many competitive face detection algorithms
Multiparameter vision testing apparatus
Compact vision testing apparatus is described for testing a large number of physiological characteristics of the eyes and visual system of a human subject. The head of the subject is inserted into a viewing port at one end of a light-tight housing containing various optical assemblies. Visual acuity and other refractive characteristics and ocular muscle balance characteristics of the eyes of the subject are tested by means of a retractable phoroptor assembly carried near the viewing port and a film cassette unit carried in the rearward portion of the housing (the latter selectively providing a variety of different visual targets which are viewed through the optical system of the phoroptor assembly). The visual dark adaptation characteristics and absolute brightness threshold of the subject are tested by means of a projector assembly which selectively projects one or both of a variable intensity fixation target and a variable intensity adaptation test field onto a viewing screen located near the top of the housing
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