Time filter

Source Type

Lamía, Greece

Aliferis G.,Aristotle University of Thessaloniki | Kofinas G.,University of Aegean | Zarikas V.,ATEI of Central Greece
Physical Review D - Particles, Fields, Gravitation and Cosmology

A novel cosmological scenario, capable of generating the observed baryon number at the electroweak scale for very small charge parity violating angles, is presented. The proposed mechanism can be applied in conventional Friedmann-Robertson-Walker cosmology, but becomes extremely efficient due to accretion in the context of early cosmic expansion with high-energy modifications. Assuming that our Universe is a Randall-Sundrum brane, baryon asymmetry can easily be produced by Hawking radiation of very small primordial black holes. The Hawking radiation reheats a spherical region around every black hole to a high temperature and the electroweak symmetry is restored there. A domain wall is formed separating the region with the symmetric vacuum from the asymmetric region where electroweak baryogenesis takes place. First order phase transition is not needed. The black hole's lifetime is prolonged due to accretion, resulting in strong efficiency of the baryon producing mechanism. The black hole mass range allowed by the mechanism includes masses that are energetically favored to be produced from interactions around the higher dimensional Planck scale. © 2015 American Physical Society. Source

Kofinas G.,University of Aegean | Zarikas V.,ATEI of Central Greece | Zarikas V.,Aristotle University of Thessaloniki
Journal of Cosmology and Astroparticle Physics

New general spherically symmetric solutions have been derived with a cosmological "constant" Λ as a source. This Λ term is not constant but it satisfies the properties of the asymptotically safe gravity at the ultraviolet fixed point. The importance of these solutions comes from the fact that they may describe the near to the centre region of black hole spacetimes as this is modified by the Renormalization Group scaling behaviour of the fields. The consistent set of field equations which respect the Bianchi identities is derived and solved. One of the solutions (with conventional sign of temporal-radial metric components) is timelike geodesically complete, and although there is still a curvature divergent origin, this is never approachable by an infalling massive particle which is reflected at a finite distance due to the repulsive origin. Another family of solutions (of both signatures) range from a finite radius outwards, they cannot be extended to the centre of spherical symmetry, and the curvature invariants are finite at the minimum radius. Source

Zarikas V.,ATEI of Central Greece | Chrysikos T.,University of Patras | Anagnostou K.E.,ATEI of Central Greece | Kotsopoulos S.,University of Patras | And 7 more authors.
10th International Conference, ELEKTRO 2014 - Proceedings

The present work describes the telemetric wireless communication system of a measuring station, implemented at the hot water source place. The telemetric unit of the measuring station collects continuously data of various physicochemical factors. The integrated systems is able to continuously measure, process and transmit via a radio transmitter data regarding radon, OPR, conductivity, water temperature and PH. An additional unit receives and stores data in convenient form for data analysis. The second part of the work presents a statistical study of the transmitted data with a novel general linear model analysis that selects the best fitting polynomial model for future prediction. © 2014 IEEE. Source

Zarikas V.,ATEI of Central Greece | Chrysikos T.,University of Patras | Anagnostou K.E.,ATEI of Central Greece | Kotsopoulos S.,University of Patras | And 7 more authors.

An implemented communication wireless telemetric system is presented. It has been built to serve as a measuring station at Thermopiles hot springs. The present work analyzes the method applying several models for adjusting and optimizing the functions of the system. The system also includes a unit that receives and stores data in an appropriate form, ready to be used for statistics. Data of critical physicochemical parameters are continuously measured, processed and transmitted over a wireless link. Path loss is investigated in order to ensure reliable signal reception. In the examined case study of low SNR region with the integrated in the open field sensors, missing data can be a common occurrence. The development of a mathematical technique, based on best prediction, for mitigating the missing values problem is of great significance in establishing a reliable system of wireless telemetry. A novel technique for handling missing values is proposed. An algorithm that evaluates missing values for imputation has been developed, based on a new general linear model analysis for prediction. The full detailed code, is explained and applied on the data that have been captured by the measuring station. Source

Discover hidden collaborations