Numerical treatment of two‐parameter singularly perturbed parabolic convection diffusion problems with non‐smooth data

[EN]In the present work, we consider a parabolic convection-diffusion-reaction problem where the diffusion and convection terms are multiplied by two small parameters, respectively. In addition, we assume that the convection coefficient and the source term of the partial differential equation have a jump discontinuity. The presence of perturbation parameters leads to the boundary and interior layers phenomenawhose appropriate numerical approximation is themain goal of this paper. We have developed a uniform numerical method, which converges almost linearly in space and time on a piecewise uniform space adaptive Shishkin-type mesh and uniform mesh in time. Error tables based on several examples show the convergence of the numerical solutions. In addition, several numerical simulations are presented to show the effectiveness of resolving layer behavior and their locations

RECODIS : Resilient communication services protecting end-user applications from disaster-based failures

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Nucleon-Nucleon interaction, charge symmetry breaking and renormalization

We study the interplay between charge symmetry breaking and renormalization in the NN system for s-waves. We find a set of universality relations which disentangle explicitly the known long distance dynamics from low energy parameters and extend them to the Coulomb case. We analyze within such an approach the One-Boson-Exchange potential and the theoretical conditions which allow to relate the proton-neutron, proton-proton and neutron-neutron scattering observables without the introduction of extra new parameters and providing good phenomenological success.Comment: 15 pages, 6 figure

Degradation of Organics in a Glow Discharge Under Martian Conditions

The primary objective of this project is to understand the consequences of glow electrical discharges on the chemistry and biology of Mars. The possibility was raised some time ago that the absence of organic material and carbonaceous matter in the Martian soil samples studied by the VikinG Landers might be due in part to an intrinsic atmospheric mechanism such as glow discharge. The high probability for dust interactions during Martian dust storms and dust devils, combined with the cold, dry climate of Mars most likely results in airborne dust that is highly charged. Such high electrostatic potentials generated during dust storms on Earth are not permitted in the low-pressure CO2 environment on Mars; therefore electrostatic energy released in the form of glow discharges is a highly likely phenomenon. Since glow discharge methods are used for cleaning and sterilizing surfaces throughout industry, the idea that dust in the Martian atmosphere undergoes a cleaning action many times over geologic time scales appears to be a plausible one

Imaging Tests for Predicting the Presence of Difficult Airway in Head and Neck Cancer Patients Undergoing Otorhinolaryngological Surgery

Patients with head and neck cancers represent a challenge for the surgical team from many points of view, but, especially, the surgical moment where greater stress generated corresponds to the perioperative management of the airway, because in many occasions we can face unexpected situations, most of the time, incidental findings can hinder ventilation and endotracheal intubation. Gutierrez et al., in 2018, decided to study four tomography measures and their correlation in anesthesia records with airway management difficulties. Material and methods: A retrospective, observational study was carried out in 104 patients operated by head and neck cancers over a period of 36 months, only in those with access to tomographic records. Four tomographic measurements were considered and were statistically related to the extreme degrees of visualization of the glottis (Cormack III–IV) and the presence of the physical examination of Mallampati III–IV. Results: After performing a multivariate model in the group of extreme degrees of visualization of the glottis, the results were not statistically significant (p > 0.05; 95% CI: 0.030–2.31: EPI/PPW, 0.018–1.37 TB/PPW). In the Mallampati III–IV group, in the multivariate model only the VC/PPW showed clinically significant results (p < 0.05; 95% CI: 0.104–8.53). Conclusions: Tomographic measurements and the physical examination predictors could represent a useful guide in the prediction of the difficult airway in these patients

Visual vs auditory augmented reality for indoor guidance

Indoor navigation systems are not widely used due to the lack of effective indoor tracking technology. Augmented Reality (AR) is a natural medium for presenting information in indoor navigation tools. However, augmenting the environment with visual stimuli may not always be the most appropriate method to guide users, e.g., when they are performing some other visual task or they suffer from visual impairments. This paper presents an AR app to support visual and auditory stimuli that we have developed for indoor guidance. A study (N=20) confirms that the participants reached the target when using two types of stimuli, visual and auditory. The AR visual stimuli outperformed the auditory stimuli in terms of time and overall distance travelled. However, the auditory stimuli forced the participants to pay more attention, and this resulted in better memorization of the route. These performance outcomes were independent of gender and age. Therefore, in addition to being easy to use, auditory stimuli promote route retention and show potential in situations in which vision cannot be used as the primary sensory channel or when spatial memory retention is important. We also found that perceived physical and mental efforts affect the subjective perception about the AR guidance app

A New Hydrogen Sensor Based on a Pt/GaAs Schottky Diode

4 páginas, 7 figuras, 1 tabla.-- PACS: 82.45.Jn; 07.07.Df; 85.30.Hi.A new hydrogen-sensitive detector based on a Pt/GaAs Schottky diode has been fabricated. The devices have beencharacterized by dark current-voltage and capacitance-voltage measurements, as a function of temperature and gas phasecomposition. At 150°C, the detection limit for hydrogen is 6 ppm in a nitrogen environment and 200 ppm in air.Peer reviewe

Characterizing the Performance of the Wheel Electrostatic Spectrometer

A Wheel Electrostatic Spectrometer has been developed as a surveying tool to be incorporated into a Martian rover design. Electrostatic sensors with various protruding cover insulators are embedded into a prototype rover wheel. When these insulators come into contact with a surface, a charge develops on the cover insulator through tribocharging. A charge spectrum is created by analyzing the accumulated charge on each of the dissimilar cover insulators. This charge spectrum can be used to determine differences in Martian regolith properties. In this study, we analyzed the repeatability of the measurements for this sensor package and found that the sensor repeatability lies within one standard deviation of the noise in the signal. In addition, we tested the need for neutralizing the surface charge on the cover insulators and discovered a need to discharge the sensor cover insulators after each revolution. Future work includes an electronics redesign to reduce noise and a Martian pressure static elimination tool that can be used to neutralize the charge on the sensor cover insulators after each wheel revolution

Mars Dust: Characterization of Particle Size and Electrostatic Charge Distribution

Some of the latest pictures of Mars surface sent by NASA's Spirit rover in early January, 2004, show very cohesive, "mud-like" dust layers. Significant amounts of dust clouds are present in the atmosphere of Mars [1-4]. NASA spacecraft missions to Mars confirmed hypotheses from telescopic work that changes observed in the planet's surface markings are caused by wind-driven redistribution of dust. In these dust storms, particles with a wide range of diameters (less than 1 micrometer to 50 micrometers) are a serious problem to solar cells, spacecraft, and spacesuits. Dust storms may cover the entire planet for an extended period of time [5]. It is highly probable that the particles are charged electrostatically by triboelectrification and by UV irradiation