A Detail Based Method for Linear Full Reference Image Quality Prediction

In this paper, a novel Full Reference method is proposed for image quality assessment, using the combination of two separate metrics to measure the perceptually distinct impact of detail losses and of spurious details. To this purpose, the gradient of the impaired image is locally decomposed as a predicted version of the original gradient, plus a gradient residual. It is assumed that the detail attenuation identifies the detail loss, whereas the gradient residuals describe the spurious details. It turns out that the perceptual impact of detail losses is roughly linear with the loss of the positional Fisher information, while the perceptual impact of the spurious details is roughly proportional to a logarithmic measure of the signal to residual ratio. The affine combination of these two metrics forms a new index strongly correlated with the empirical Differential Mean Opinion Score (DMOS) for a significant class of image impairments, as verified for three independent popular databases. The method allowed alignment and merging of DMOS data coming from these different databases to a common DMOS scale by affine transformations. Unexpectedly, the DMOS scale setting is possible by the analysis of a single image affected by additive noise.Comment: 15 pages, 9 figures. Copyright notice: The paper has been accepted for publication on the IEEE Trans. on Image Processing on 19/09/2017 and the copyright has been transferred to the IEE

Space Time MUSIC: Consistent Signal Subspace Estimation for Wide-band Sensor Arrays

Wide-band Direction of Arrival (DOA) estimation with sensor arrays is an essential task in sonar, radar, acoustics, biomedical and multimedia applications. Many state of the art wide-band DOA estimators coherently process frequency binned array outputs by approximate Maximum Likelihood, Weighted Subspace Fitting or focusing techniques. This paper shows that bin signals obtained by filter-bank approaches do not obey the finite rank narrow-band array model, because spectral leakage and the change of the array response with frequency within the bin create \emph{ghost sources} dependent on the particular realization of the source process. Therefore, existing DOA estimators based on binning cannot claim consistency even with the perfect knowledge of the array response. In this work, a more realistic array model with a finite length of the sensor impulse responses is assumed, which still has finite rank under a space-time formulation. It is shown that signal subspaces at arbitrary frequencies can be consistently recovered under mild conditions by applying MUSIC-type (ST-MUSIC) estimators to the dominant eigenvectors of the wide-band space-time sensor cross-correlation matrix. A novel Maximum Likelihood based ST-MUSIC subspace estimate is developed in order to recover consistency. The number of sources active at each frequency are estimated by Information Theoretic Criteria. The sample ST-MUSIC subspaces can be fed to any subspace fitting DOA estimator at single or multiple frequencies. Simulations confirm that the new technique clearly outperforms binning approaches at sufficiently high signal to noise ratio, when model mismatches exceed the noise floor.Comment: 15 pages, 10 figures. Accepted in a revised form by the IEEE Trans. on Signal Processing on 12 February 1918. @IEEE201

Viscous corrections to the resistance of nano-junctions: a dispersion relation approach

It is well known that the viscosity of a homogeneous electron liquid diverges in the limits of zero frequency and zero temperature. A nanojunction breaks translational invariance and necessarily cuts off this divergence. However, the estimate of the ensuing viscosity is far from trivial. Here, we propose an approach based on a Kramers-Kr\"onig dispersion relation, which connects the zero-frequency viscosity, $\eta(0)$, to the high-frequency shear modulus, $\mu_{\infty}$, of the electron liquid via $\eta(0) =\mu_{\infty} \tau$, with $\tau$ the junction-specific momentum relaxation time. By making use of a simple formula derived from time-dependent current-density functional theory we then estimate the many-body contributions to the resistance for an integrable junction potential and find that these viscous effects may be much larger than previously suggested for junctions of low conductance.Comment: 6 pages, 5 figures, Revised versio

Microbial Challenges to Extending Usage of Rio Grande River Water

Despite its critical role in agriculture and potable water supply for the region, few studies have evaluated the microbial quality of the Rio Grande River, especially for the parasites Cryptosporidium and Giardia. Cryptosporidium and Giardia cause diarrheal illness and have been responsible for numerous waterborne and foodborne disease outbreaks. Cryptosporidiosis, the disease caused by Cryptosporidium, may be fatal in people with weakened immune systems and there is currently no effective treatment for the disease. During the irrigation season, water is released from upstream reservoirs and the river water is used by El Paso as a potable supply. During the non-irrigation season (October through February), river flows are comprised of agricultural return flows and wastewater treatment plant effluents. Due to recent drought conditions in the region, winter return flows in the El Paso area are largely wastewater effluents. Our monitoring results revealed that winter return flows contain 5 and 100 times higher average levels of Cryptosporidium and Giardia, respectively, than irrigation season river water. Recently, research has been proposed to evaluate the use of winter return flows for potable supply and irrigation. Conventional filtration and disinfection followed by nanofiltration or reverse osmosis have been proposed for treatment of the water to remove total dissolved solids and microorganisms. Besides Cryptosporidium and Giardia, viruses may also be present in wastewater effluents. Therefore, in addition to chemical quality issues, these microbial water quality challenges must be overcome before this underutilized water resource can be put to beneficial use

Predicting the Blur Visual Discomfort for Natural Scenes by the Loss of Positional Information

The perception of the blur due to accommodation failures, insufficient optical correction or imperfect image reproduction is a common source of visual discomfort, usually attributed to an anomalous and annoying distribution of the image spectrum in the spatial frequency domain. In the present paper, this discomfort is attributed to a loss of the localization accuracy of the observed patterns. It is assumed, as a starting perceptual principle, that the visual system is optimally adapted to pattern localization in a natural environment. Thus, since the best possible accuracy of the image patterns localization is indicated by the positional Fisher Information, it is argued that the blur discomfort is strictly related to a loss of this information. Following this concept, a receptive field functional model, tuned to common features of natural scenes, is adopted to predict the visual discomfort. It is a complex-valued operator, orientation-selective both in the space domain and in the spatial frequency domain. Starting from the case of Gaussian blur, the analysis is extended to a generic type of blur by applying a positional Fisher Information equivalence criterion. Out-of-focus blur and astigmatic blur are presented as significant examples. The validity of the proposed model is verified by comparing its predictions with subjective ratings. The model fits linearly with the experiments reported in independent databases, based on different protocols and settings.Comment: 12 pages, 8 figures, article submitted to Vision Research (Elsevier) Journal in July 202

Predicting blur visual discomfort for natural scenes by the loss of positional information

The perception of blur due to accommodation failures, insufficient optical correction or imperfect image reproduction is a common source of visual discomfort, usually attributed to an anomalous and annoying distribution of the image spectrum in the spatial frequency domain. In the present paper, this discomfort is related to a loss of the localization accuracy of the observed patterns. It is assumed, as a starting perceptual principle, that the visual system is optimally adapted to pattern localization in a natural environment. Thus, since the best possible accuracy of the image patterns localization is indicated by the positional Fisher Information, it is argued that blur discomfort is strictly related to a loss of this information. Following this concept, a receptive field functional model is adopted to predict the visual discomfort. It is a complex-valued operator, orientation-selective both in the space domain and in the spatial frequency domain. Starting from the case of Gaussian blur, the analysis is extended to a generic type of blur by applying a positional Fisher Information equivalence criterion. Out-of-focus blur and astigmatic blur are presented as significant examples. The validity of the proposed model is verified by comparing its predictions with subjective ratings. The model fits linearly with the experiments reported in independent databases, based on different protocols and settings

Microstructure evolution and mechanical properties of hot deformed Mg9Al1Zn samples containing a friction stir processed zone

During the last decade, FSP of magnesium alloys has become more popular due to the potential microstructure refinement of their eutectic phases, and interest has increased around the AZ1 that is one of the most commercially used magnesium alloys. In this work, high pressure die cast AZ91 plates were tensile tested at high temperatures after friction stir processing (FSP), with the stirred region in the middle of the gauge length. Samples deformed at 350 °C revealed an increment of ductility that was doubled as compared to those deformed at 300 °C and a strengthening of the nugget was measured by Vickers microhardness (HV). The correlation of HV average values to local grain size confirmed the validity of the Hall–Petch type equation where stress is replaced by hardness. X-rays diffraction and electrical conductivity highlighted the potential increment of solute atoms in solid solution during FSP. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) investigations performed on as-FSPed and hot deformed samples determined MgAlZn and AlMn particles type evolution through statistical analysis that supported mechanical properties and the strengthening mechanisms. Keywords: AZ91, Friction stir processing, Mechanical properties, Microstructure, SEM, TE

Turning earthworms into moonworms: Earthworms colonization of lunar regolith as a bioengineering approach supporting future crop growth in space

The earthworms beneficial effects on soils may be promising to improve lunar soil fertility, enabling the use of local substrates for space farming. Herein, we investigated the effects of the lunar regolith simulant (LHS-1) at different concentrations in cow manure mixtures on the survival and fitness of Eisenia fetida. During 14 and 60-day experiments, although E. fetida showed an increased mortality with LHS-1 alone, most of the population survived. More numerous tunnels were observed when exposed to the higher concentrations of LHS-1 (poor in nutrients for earthworms). This may be related to an increased mobility for food search. The cocoons production was not affected by different substrate treatments, except for the highest concentration of LHS-1. No effects of different LHS-1 concentrations on the amount of ingested substrate were recorded. This study shows that E. fetida can potentially colonize lunar regolith representing a future valuable biological tool for supporting crops growth on the Moon

Measurements of vehicle pollutants in a high-traffic urban area by a multiwavelength dial approach: Correlation between two different motor vehicle pollutants

The development and improvement of monitoring techniques to measure the concentration of pollutants in the atmosphere are a starting point to guarantee high levels of human health and environmental safety. The combination of lidar and dial techniques, by measuring backscattering signals and reconstructing the map of their concentrations, can be used to provide detailed information about the presence of aerosols, particulate and pollutions. Moreover, by using a multiwavelength approach, it is possible to increase the measurement accuracy and reliability. In this work, the dial approach is used to monitor the pollution in a very congested urban area with high trac. In order to provide a validation of the results, correlation analyses between the measured pollutants was performed. A new lidar analysis method, based on the least-square minimization technique, was introduced and demonstrated to work properly. The dial capability to detect polluted areas was shown—and by correlation analysis—also the possibility to identify the source of pollutions can be performed