A novel on-board Unit to accelerate the penetration of ITS services

In-vehicle connectivity has experienced a big expansion in recent years. Car manufacturers have mainly proposed OBU-based solutions, but these solutions do not take full advantage of the opportunities of inter-vehicle peer-to-peer communications. In this paper we introduce GRCBox, a novel architecture that allows OEM user-devices to directly communicate when located in neighboring vehicles. In this paper we also describe EYES, an application we developed to illustrate the type of novel applications that can be implemented on top of the GRCBox. EYES is an ITS overtaking assistance system that provides the driver with real-time video fed from the vehicle located in front. Finally, we evaluated the GRCbox and the EYES application and showed that, for device-to-device communication, the performance of the GRCBox architecture is comparable to an infrastructure network, introducing a negligible impact

Messiah: An ITS drive safety application

This article describes a novel safety application based on the open source navigation software OsmAnd, which runs on the Android platform. The application offers vehicles with "smart navigation", and maintains a network of the vehicles that use our application. The process of network creation and maintenance is important as our application enables vehicles to communicate with one another to exchange useful information. The main function of the application is to inform vehicles of relevant vehicles approaching, termed as "administrative vehicles" in this article, and include ambulances, police cars and fire brigades. Based on the received information, our application notifies the driver, who can now take navigation decisions based on it. While developing the application, problems were found when attempting to create an Ad-hoc network. A solution to the problem of managing the Ad-hoc network has been proposed and is under development

Higgs-Stoponium Mixing Near the Stop-Antistop Threshold

Supersymmetric extensions of the standard model contain additional heavy neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This system exhibits interesting field theoretic phenomena when the Higgs mass is close to the stop-antistop production threshold. Existing work in the literature has examined the digluon-to-diphoton cross section near threshold and has focused on enhancements in the cross section that might arise either from the perturbative contributions to the Higgs-to-digluon and Higgs-to-diphoton form factors or from mixing of the Higgs boson with stoponium states. Near threshold, enhancements in the relevant amplitudes that go as inverse powers of the stop-antistop relative velocity require resummations of perturbation theory and/or nonperturbative treatments. We present a complete formulation of threshold effects at leading order in the stop-antistop relative velocity in terms of nonrelativistic effective field theory. We give detailed numerical calculations for the case in which the stop-antistop Green's function is modeled with a Coulomb-Schr\"odinger Green's function. We find several general effects that do not appear in a purely perturbative treatment. Higgs-stop-antistop mixing effects displace physical masses from the threshold region, thereby rendering the perturbative threshold enhancements inoperative. In the case of large Higgs-stop-antistop couplings, the displacement of a physical state above threshold substantially increases its width, owing to its decay width to a stop-antistop pair, and greatly reduces its contribution to the cross section.Comment: 45 pages, 13 figures, minor corrections, references added, figures 2--5 updated, version published in Phys. Rev.

Phase transition in conservative diffusive contact processes

We determine the phase diagrams of conservative diffusive contact processes by means of numerical simulations. These models are versions of the ordinary diffusive single-creation, pair-creation and triplet-creation contact processes in which the particle number is conserved. The transition between the frozen and active states was determined by studying the system in the subcritical regime and the nature of the transition, whether continuous or first order, was determined by looking at the fractal dimension of the critical cluster. For the single-creation model the transition remains continuous for any diffusion rate. For pair- and triplet-creation models, however, the transition becomes first order for high enough diffusion rate. Our results indicate that in the limit of infinite diffusion rate the jump in density equals 2/3 for the pair-creation model and 5/6 for the triplet-creation model

Cosmology with Varying Constants

The idea of possible time or space variations of the `fundamental' constants of nature, although not new, is only now beginning to be actively considered by large numbers of researchers in the particle physics, cosmology and astrophysics communities. This revival is mostly due to the claims of possible detection of such variations, in various different contexts and by several groups. Here, I present the current theoretical motivations and expectations for such variations, review the current observational status, and discuss the impact of a possible confirmation of these results in our views of cosmology and physics as a whole.Comment: 14 pages, no figures. Essay to appear in Phil. Trans. Roy. Soc. Lond. A Triennial Series (Christmas 2002 Issue

Electron microscopy study of CeOx–Pd/α-Al2O3 catalysts for methane dry reforming

We have investigated the interaction between Pd and Ce in a 0.47 wt % CeOx–Pd 1 wt %/ -Al2O3 catalyst that is used in the reforming reaction of CH4 with CO2. The freshly reduced catalyst was characterized by various electron microscopy techniques, such as elemental mapping, Z-contrast imaging, and electron energy-loss spectroscopy to understand the role of Ce on a microscopic scale. The high spatial resolution elemental mapping indicates that CeOx is located in close proximity of the palladium nanoparticles. High-resolution lattice images and energy-loss spectra obtained in the vicinity of the Pd particles show an anisotropic distribution of CeOx crystallites limited to the interface region between Pd and the substrate but not covering the surface of the Pd nanoparticles. Energy-loss near edge fine structure of Pd M edges reveals that the Pd nanoparticles are not oxidized.Fil: Moreno, M. S.. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Wang, Feiya. National Institute for Nanotechnology; CanadáFil: Malac, M.. National Institute for Nanotechnology; CanadáFil: Kasama, T.. University of Cambridge; Reino UnidoFil: Gigola, Carlos Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Costilla, Ignacio Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Sánchez, M. D.. Universidad Nacional del Sur. Departamento de Física; Argentin

Hydration and anomalous solubility of the Bell-Lavis model as solvent

We address the investigation of the solvation properties of the minimal orientational model for water, originally proposed by Bell and Lavis. The model presents two liquid phases separated by a critical line. The difference between the two phases is the presence of structure in the liquid of lower density, described through orientational order of particles. We have considered the effect of small inert solute on the solvent thermodynamic phases. Solute stabilizes the structure of solvent, by the organization of solvent particles around solute particles, at low temperatures. Thus, even at very high densities, the solution presents clusters of structured water particles surrounding solute inert particles, in a region in which pure solvent would be free of structure. Solute intercalates with solvent, a feature which has been suggested by experimental and atomistic simulation data. Examination of solute solubility has yielded a minimum in that property, which may be associated with the minimum found for noble gases. We have obtained a line of minimum solubility (TmS) across the phase diagram, accompanying the line of maximum in density (TMD). This coincidence is easily explained for non-interacting solute and it is in agreement with earlier results in the literature. We give a simple argument which suggests that interacting solute would dislocate TmS to higher temperatures

Remarks on the Racetrack Scheme

There are only a small number of ideas for stabilizing the moduli of string theory. One of the most appealing of these is the racetrack mechanism, in which a delicate interplay between two strongly interacting gauge groups fixes the value of the coupling constant. In this note, we explore this scenario. We find that quite generally, some number of discrete tunings are required in order that the mechanism yield a small gauge coupling. Even then, there is no sense in which a weak coupling approximation is valid. On the other hand, certain holomorphic quantities can be computed, so such a scheme is in principle predictive. Searching for models which realize this mechanism is thus of great interest. We also remark on cosmology in these schemes.Comment: 20 pp, latex, discussion of calculability modifie