220 research outputs found
Incorporating appliance usage patterns for non-intrusive load monitoring and load forecasting
This paper proposes a novel Non-Intrusive Load
Monitoring (NILM) method which incorporates appliance usage
patterns (AUPs) to improve performance of active load identi-
fication and forecasting. In the first stage, the AUPs of a given
residence were learnt using a spectral decomposition based standard
NILM algorithm. Then, learnt AUPs were utilized to bias
the priori probabilities of the appliances through a specifically
constructed fuzzy system. The AUPs contain likelihood measures
for each appliance to be active at the present instant based on
the recent activity/inactivity of appliances and the time of day.
Hence, the priori probabilities determined through the AUPs
increase the active load identification accuracy of the NILM
algorithm. The proposed method was successfully tested for
two standard databases containing real household measurements
in USA and Germany. The proposed method demonstrates an
improvement in active load estimation when applied to the
aforementioned databases as the proposed method augments the
smart meter readings with the behavioral trends obtained from
AUPs. Furthermore, a residential power consumption forecasting
mechanism, which can predict the total active power demand of
an aggregated set of houses, five minutes ahead of real time, was
successfully formulated and implemented utilizing the proposed
AUP based technique
The automated detection of proliferative diabetic retinopathy using dual ensemble classification
Objective: Diabetic retinopathy (DR) is a retinal vascular disease that is caused by complications of diabetes. Proliferative diabetic retinopathy (PDR) is the advanced stage of the disease which carries a high risk of severe visual impairment. This stage is characterized by the growth of abnormal new vessels. We aim to develop a method for the automated detection of new vessels from retinal images.
Methods: This method is based on a dual classification approach. Two vessel segmentation approaches are applied to create two separate binary vessel maps which each hold vital information. Local morphology, gradient and intensity features are measured using each binary vessel map to produce two separate 21-D feature vectors. Independent classification is performed for each feature vector using an ensemble system of bagged decision trees. These two independent outcomes are then combined to a produce a final decision.
Results: Sensitivity and specificity results using a dataset of 60 images are 1.0000 and 0.9500 on a per image basis.
Conclusions: The described automated system is capable of detecting the presence of new vessels
Pixel-z: Studying Substructure and Stellar Populations in Galaxies out to z~3 using Pixel Colors I. Systematics
We perform a pixel-by-pixel analysis of 467 galaxies in the GOODS-VIMOS
survey to study systematic effects in extracting properties of stellar
populations (age, dust, metallicity and SFR) from pixel colors using the
pixel-z method. The systematics studied include the effect of the input stellar
population synthesis model, passband limitations and differences between
individual SED fits to pixels and global SED-fitting to a galaxy's colors. We
find that with optical-only colors, the systematic errors due to differences
among the models are well constrained. The largest impact on the age and SFR
e-folding time estimates in the pixels arises from differences between the
Maraston models and the Bruzual&Charlot models, when optical colors are used.
This results in systematic differences larger than the 2{\sigma} uncertainties
in over 10 percent of all pixels in the galaxy sample. The effect of
restricting the available passbands is more severe. In 26 percent of pixels in
the full sample, passband limitations result in systematic biases in the age
estimates which are larger than the 2{\sigma} uncertainties. Systematic effects
from model differences are reexamined using Near-IR colors for a subsample of
46 galaxies in the GOODS-NICMOS survey. For z > 1, the observed optical/NIR
colors span the rest frame UV-optical SED, and the use of different models does
not significantly bias the estimates of the stellar population parameters
compared to using optical-only colors. We then illustrate how pixel-z can be
applied robustly to make detailed studies of substructure in high redshift
galaxies such as (a) radial gradients of age, SFR, sSFR and dust and (b) the
distribution of these properties within subcomponents such as spiral arms and
clumps. Finally, we show preliminary results from the CANDELS survey
illustrating how the new HST/WFC3 data can be exploited to probe substructure
in z~1-3 galaxies.Comment: 37 pages, 21 figures, submitted to Ap
Combining Fine- and Coarse-Grained Classifiers for Diabetic Retinopathy Detection
Visual artefacts of early diabetic retinopathy in retinal fundus images are
usually small in size, inconspicuous, and scattered all over retina. Detecting
diabetic retinopathy requires physicians to look at the whole image and fixate
on some specific regions to locate potential biomarkers of the disease.
Therefore, getting inspiration from ophthalmologist, we propose to combine
coarse-grained classifiers that detect discriminating features from the whole
images, with a recent breed of fine-grained classifiers that discover and pay
particular attention to pathologically significant regions. To evaluate the
performance of this proposed ensemble, we used publicly available EyePACS and
Messidor datasets. Extensive experimentation for binary, ternary and quaternary
classification shows that this ensemble largely outperforms individual image
classifiers as well as most of the published works in most training setups for
diabetic retinopathy detection. Furthermore, the performance of fine-grained
classifiers is found notably superior than coarse-grained image classifiers
encouraging the development of task-oriented fine-grained classifiers modelled
after specialist ophthalmologists.Comment: Pages 12, Figures
Incorporating spatial information for microaneurysm detection in retinal images
The presence of microaneurysms(MAs) in retinal images is a pathognomonic sign of Diabetic Retinopathy (DR). This is one of the leading causes of blindness in the working population worldwide. This paper introduces a novel algorithm that combines information from spatial views of the retina for the purpose of MA detection. Most published research in the literature has addressed the problem of detecting MAs from single retinal images. This work proposes the incorporation of information from two spatial views during the detection process. The algorithm is evaluated using 160 images from 40 patients seen as part of a UK diabetic eye screening programme which contained 207 MAs. An improvement in performance compared to detection from an algorithm that relies on a single image is shown as an increase of 2% ROC score, hence demonstrating the potential of this method
Planck's Dusty GEMS: Gravitationally lensed high-redshift galaxies discovered with the Planck survey
We present an analysis of 11 bright far-IR/submm sources discovered through a
combination of the Planck survey and follow-up Herschel-SPIRE imaging. Each
source has a redshift z=2.2-3.6 obtained through a blind redshift search with
EMIR at the IRAM 30-m telescope. Interferometry obtained at IRAM and the SMA,
and optical/near-infrared imaging obtained at the CFHT and the VLT reveal
morphologies consistent with strongly gravitationally lensed sources.
Additional photometry was obtained with JCMT/SCUBA-2 and IRAM/GISMO at 850 um
and 2 mm, respectively. All objects are bright, isolated point sources in the
18 arcsec beam of SPIRE at 250 um, with spectral energy distributions peaking
either near the 350 um or the 500 um bands of SPIRE, and with apparent
far-infrared luminosities of up to 3x10^14 L_sun. Their morphologies and sizes,
CO line widths and luminosities, dust temperatures, and far-infrared
luminosities provide additional empirical evidence that these are strongly
gravitationally lensed high-redshift galaxies. We discuss their dust masses and
temperatures, and use additional WISE 22-um photometry and template fitting to
rule out a significant contribution of AGN heating to the total infrared
luminosity. Six sources are detected in FIRST at 1.4 GHz. Four have flux
densities brighter than expected from the local far-infrared-radio correlation,
but in the range previously found for high-z submm galaxies, one has a deficit
of FIR emission, and 6 are consistent with the local correlation. The global
dust-to-gas ratios and star-formation efficiencies of our sources are
predominantly in the range expected from massive, metal-rich, intense,
high-redshift starbursts. An extensive multi-wavelength follow-up programme is
being carried out to further characterize these sources and the intense
star-formation within them.Comment: A&A accepte
The Structures of Distant Galaxies V: The Evolution of Galaxy Structure in Stellar Mass at z < 1
Galaxy structure and morphology is nearly always studied using the light
originating from stars, however ideally one is interested in measuring
structure using the stellar mass distribution. Not only does stellar mass trace
out the underlying distribution of matter, it also minimises the effects of
star formation and dust on the appearance and structure of a galaxy. We present
in this paper a study of the stellar mass distributions and structures of
galaxies at z<1 as found within the GOODS fields. We use pixel by pixel
K-corrections to construct stellar mass and mass-to-light ratio maps of 560
galaxies of known morphology at magnitudes z_{850}<24. We measure structural
and size parameters using these stellar mass maps, as well as on ACS BViz band
imaging. This includes investigating the structural CAS-Gini-M_{20} parameters
and half-light radius for each galaxy. We compare structural parameters and
half-light radii in the ACS z_{850}-band and stellar mass maps, finding no
systematic bias introduced by measuring galaxy sizes in z_{850}. We furthermore
investigate relations between structural parameters in the ACS BViz bands and
stellar mass maps, and compare our result to previous morphological studies.
Combinations of various parameters in stellar mass generally reveal clear
separations between early and late type morphologies, but cannot easily
distinguish between star formation and dynamically disturbed systems. We also
show that while ellipticals and early-type spirals have fairly constant CAS
values at z<1 we find a tendency for late-type spiral and peculiar
morphological types to have a higher A(M_{*}) at higher redshift. We argue that
this, and the large fraction of peculiars that appear spiral-like in stellar
mass maps, are possible evidence for either an active bulge formation in some
late-type disks at z<1 or the presence of minor merger events.Comment: 27 pages, MNRAS in pres
Retinal Vascular Tortuosity and Diameter Associations with Adiposity and Components of Body Composition.
OBJECTIVE: The aim of this study was to assess whether adiposity or body composition relates to microvascular characteristics of the retina, indicative of cardiometabolic function. METHODS: A fully automated QUARTZ software processed retinal images from 68,550 UK Biobank participants (aged 40-69 years). Differences in retinal vessel diameter and tortuosity with body composition measures from the Tanita analyzer were obtained by using multilevel regression analyses adjusted for age, sex, ethnicity, clinic, smoking, and Townsend deprivation index. RESULTS: Venular tortuosity and diameter increased by approximately 2% (P < 10-300 ) and 0.6 μm (P < 10-6 ), respectively, per SD increase in BMI, waist circumference index, waist-hip ratio, total body fat mass index, and fat-free mass index (FFMI). Venular associations with adiposity persisted after adjustment for FFMI, whereas associations with FFMI were weakened by FMI adjustment. Arteriolar diameter (not tortuosity) narrowing with FFMI was independent of adiposity (-0.6 μm; -0.7 to -0.4 μm per SD increment of FFMI), while adiposity associations with arteriolar diameter were largely nonsignificant after adjustment for FFMI. CONCLUSIONS: This demonstrates, on an unprecedented scale, that venular tortuosity and diameter are more strongly associated with adiposity, whereas arteriolar diameter relates more strongly to fat-free mass. Different attributes of the retinal microvasculature may reflect distinct roles of body composition and fatness on the cardiometabolic system
The redshift distribution of dusty star forming galaxies from the SPT survey
We use the Atacama Large Millimeter/submillimeter Array (ALMA) in Cycle 1 to
determine spectroscopic redshifts of high-redshift dusty star-forming galaxies
(DSFGs) selected by their 1.4mm continuum emission in the South Pole Telescope
(SPT) survey. We present ALMA 3mm spectral scans between 84-114GHz for 15
galaxies and targeted ALMA 1mm observations for an additional eight sources.
Our observations yield 30 new line detections from CO, [CI] , [NII] , H_2O and
NH_3. We further present APEX [CII] and CO mid-J observations for seven sources
for which only a single line was detected in spectral-scan data from ALMA Cycle
0 or Cycle 1. We combine the new observations with previously published and new
mm/submm line and photometric data of the SPT-selected DSFGs to study their
redshift distribution. The combined data yield 39 spectroscopic redshifts from
molecular lines, a success rate of >85%. Our sample represents the largest data
set of its kind today and has the highest spectroscopic completeness among all
redshift surveys of high-z DSFGs. The median of the redshift distribution is
z=3.9+/-0.4, and the highest-redshift source in our sample is at z=5.8. We
discuss how the selection of our sources affects the redshift distribution,
focusing on source brightness, selection wavelength, and strong gravitational
lensing. We correct for the effect of gravitational lensing and find the
redshift distribution for 1.4mm-selected sources with a median redshift of
z=3.1+/-0.3. Comparing to redshift distributions selected at shorter
wavelengths from the literature, we show that selection wavelength affects the
shape of the redshift distribution
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