116,453 research outputs found
High resolution fire hazard index based on satellite images
In December 2015, after 3 year of activity, the FP7 project PREFER (Space-based Information Support for Prevention and REcovery of Forest Fires Emergency in the MediteRranean Area) came to an end. The project was designed to respond to the need to improve the use of satellite images in applications related to the emergency services, in particular, to forest fires. The project aimed at developing, validating and demonstrating information products based on optical and SAR (Synthetic Aperture Radar) imagery for supporting the prevention of forest fires and the recovery/damage assessment of burnt area. The present paper presents an improved version of one of the products developed under the PREFER project, which is the Daily Fire Hazard Index (DFHI)
Stereo and ToF Data Fusion by Learning from Synthetic Data
Time-of-Flight (ToF) sensors and stereo vision systems are both capable of acquiring depth information but they have complementary characteristics and issues. A more accurate representation of the scene geometry can be obtained by fusing the two depth sources. In this paper we present a novel framework for data fusion where the contribution of the two depth sources is controlled by confidence measures that are jointly estimated using a Convolutional Neural Network. The two depth sources are fused enforcing the local consistency of depth data, taking into account the estimated confidence information. The deep network is trained using a synthetic dataset and we show how the classifier is able to generalize to different data, obtaining reliable estimations not only on synthetic data but also on real world scenes. Experimental results show that the proposed approach increases the accuracy of the depth estimation on both synthetic and real data and that it is able to outperform state-of-the-art methods
Laser Based Mid-Infrared Spectroscopic Imaging – Exploring a Novel Method for Application in Cancer Diagnosis
A number of biomedical studies have shown that mid-infrared spectroscopic images can provide
both morphological and biochemical information that can be used for the diagnosis of cancer. Whilst
this technique has shown great potential it has yet to be employed by the medical profession. By
replacing the conventional broadband thermal source employed in modern FTIR spectrometers with
high-brightness, broadly tuneable laser based sources (QCLs and OPGs) we aim to solve one of the
main obstacles to the transfer of this technology to the medical arena; namely poor signal to noise
ratios at high spatial resolutions and short image acquisition times. In this thesis we take the first
steps towards developing the optimum experimental configuration, the data processing algorithms
and the spectroscopic image contrast and enhancement methods needed to utilise these high
intensity laser based sources. We show that a QCL system is better suited to providing numerical
absorbance values (biochemical information) than an OPG system primarily due to the QCL pulse
stability. We also discuss practical protocols for the application of spectroscopic imaging to cancer
diagnosis and present our spectroscopic imaging results from our laser based spectroscopic imaging
experiments of oesophageal cancer tissue
Quantified HI Morphology I: Multi-Wavelengths Analysis of the THINGS Galaxies
Galaxy evolution is driven to a large extent by interactions and mergers with
other galaxies and the gas in galaxies is extremely sensitive to the
interactions. One method to measure such interactions uses the quantified
morphology of galaxy images. Well-established parameters are Concentration,
Asymmetry, Smoothness, Gini, and M20 of a galaxy image. Thus far, the
application of this technique has mostly been restricted to restframe
ultra-violet and optical images. However, with the new radio observatories
being commissioned (MeerKAT, ASKAP, EVLA, WSRT/APERTIF, and ultimately SKA), a
new window on the neutral atomic hydrogen gas (HI) morphology of a large
numbers of galaxies will open up. The quantified morphology of gas disks of
spirals can be an alternative indicator of the level and frequency of
interaction. The HI in galaxies is typically spatially more extended and more
sensitive to low-mass or weak interactions. In this paper, we explore six
morphological parameters calculated over the extent of the stellar (optical)
disk and the extent of the gas disk for a range of wavelengths spanning UV,
Optical, Near- and Far-Infrared and 21 cm (HI) of 28 galaxies from The HI
Nearby Galaxy Survey (THINGS). Though the THINGS sample is small and contains
only a single ongoing interaction, it spans both non-interacting and
post-interacting galaxies with a wealth of multi-wavelength data. We find that
the choice of area for the computation of the morphological parameters is less
of an issue than the wavelength at which they are measured. The signal of
interaction is as good in the HI as in any of the other wavelengths in which
morphology has been used to trace the interaction rate to date, mostly
star-formation dominated ones (near- and far-ultraviolet). The Asymmetry and
M20 parameters are the ones which show the most promise as tracers of
interaction in 21 cm line observations.Comment: 16 pages, 11 figure, table 1, accepted by MNRAS, appendix not
include
Characterizing Magnetohydrodynamic Turbulence in the Small Magellanic Cloud
We investigate the nature and spatial variations of turbulence in the Small
Magellanic Cloud (SMC) by applying several statistical methods on the neutral
hydrogen (HI) column density image of the SMC and a database of isothermal
numerical simulations. By using the 3rd and 4th statistical moments we derive
the spatial distribution of the sonic Mach number (M_s) across the SMC. We find
that about 90% of the HI in the SMC is subsonic or transonic. However, edges of
the SMC `bar' have M_s=4 and may be tracing shearing or turbulent flows. Using
numerical simulations we also investigate how the slope of the spatial power
spectrum depends on both sonic and Alfven Mach numbers. This allows us to gauge
the Alfven Mach number of the SMC and conclude that its gas pressure dominates
over the magnetic pressure. The super-Alfvenic nature of the HI gas in the SMC
is also highlighted by the bispectrum, a three-point correlation function which
characterizes the level of non-Gaussianity in wave modes. We find that the
bispectrum of the SMC HI column density displays similar large-scale
correlations as numerical simulations, however it has localized enhancements of
correlations. In addition, we find a break in correlations at a scale of 160
pc. This may be caused by numerous expanding shells of a similar size
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