Radar methods for determining the thickness of dielectric layers

This paper describes two methods, the amplitude method and the method based on geometric optics. The methods were applied to practical data obtained by georadar tests. As a result, the refractive index and thickness of the investigated planar layered medium were calculated. When using the amplitude method, the refractive index of the investigated medium is 1.3, the thickness is 0.11 m. When using the method based on geometric optics, the refractive index of the investigated medium is 1.43, the thickness is 0.102 m. After comparing the results of these methods, it was found that the error of the amplitude method is higher than that of the geometrical optics method

An algorithm for prioritizing the maintenance of power transformers

This report presents an algorithm that takes into account power transformer (PT) technical conditions and their potential for failure risk assessment to help determine maintenance precedence. The technical condition integrated index is assessed through the weighted average of condition indexes determined by the results of PT traditional and special control methods. Each control type index is the three-dimensional space vector where the coordinates are next: X - damage seriousness, Y - damage development speed, Z - damage development duration. The traditional control method defect identification and coordinate determination are carried out by an expert system without any specialist participation. Risk failure assessment includes: damages of suppliers and to consumers of electricity; transformer design features; lifetime; ES transformer unit (system) failure potential. The PT unit failure potentials were calculated using the flows of failures and damage statistics of 350 reliable facts of PT damage accumulated by the ES for 20 years of operation. Firstly, priority ranking for serviceable transformer operational activities are excluded from the sample. Then there are calculated coordinates on each of the remaining transformers. It coordinates the points, which are marked by the PT plane. The plane includes three zones: additional scheduled inspections and emergency repairs. The ES ranks PT by the distance from the origin within each zone. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Space-borne Observations of Atmospheric Pre-Earthquake Signals in Seismically Active Areas: Case Study for Greece 2008-2009

We are conducting theoretical studies and practical validation of atm osphere/ionosphere phenomena preceding major earthquakes. Our approach is based on monitoring of two physical parameters from space: outgoi ng long-wavelength radiation (OLR) on the top of the atmosphere and e lectron and electron density variations in the ionosphere via GPS Tot al Electron Content (GPS/TEC). We retrospectively analyzed the temporal and spatial variations of OLR an GPS/TEC parameters characterizing the state of the atmosphere and ionosphere several days before four m ajor earthquakes (M>6) in Greece for 2008-2009: M6.9 of 02.12.08, M6. 2 02.20.08; M6.4 of 06.08.08 and M6.4 of 07.01.09.We found anomalous behavior before all of these events (over land and sea) over regions o f maximum stress. We expect that our analysis reveal the underlying p hysics of pre-earthquake signals associated with some of the largest earthquakes in Greece

Fundamental insight into the effect of carbodiimide crosslinking on cellular recognition of collagen-based scaffolds

Research on the development of collagen constructs is extremely important in the field of tissue engineering. Collagen scaffolds for numerous tissue engineering applications are frequently crosslinked with 1-ethyl-3-(3-dimethylaminopropyl-carbodiimide hydrochloride (EDC) in the presence of N-hydroxy-succinimide (NHS). Despite producing scaffolds with good biocompatibility and low cellular toxicity the influence of EDC/NHS crosslinking on the cell interactive properties of collagen has been overlooked. Here we have extensively studied the interaction of model cell lines with collagen I-based materials after crosslinking with different ratios of EDC in relation to the number of carboxylic acid residues on collagen. Divalent cation-dependent cell adhesion, via integrins α$_{1}$β$_{1}$, α$_{2}$β$_{1}$, α$_{10}$β$_{1}$ and α$_{11}$β$_{1}$, were sensitive to EDC crosslinking. With increasing EDC concentration, this was replaced with cation-independent adhesion. These results were replicated using purified recombinant I domains derived from integrin α$_{1}$ and α$_{2}$ subunits. Integrin α$_{2}$β$_{1}$-mediated cell spreading, apoptosis and proliferation were all heavily influenced by EDC crosslinking of collagen. Data from this rigorous study provides an exciting new insight that EDC/NHS crosslinking is utilising the same carboxylic side chain chemistry that is vital for native-like integrin-mediated cell interactions. Due to the ubiquitous usage of EDC/NHS crosslinked collagen for biomaterials fabrication this data is essential to have a full understanding in order to ensure optimized collagen-based material performance.This work was supported by the British Heart Foundation (Grant NH/11/1/28922, RG/15/4/31268, SP/15/7/31561 and RG/09/003/27122) and the ERC Advanced Grant 320598 3D-E. D. V. Bax is funded by the Peoples Programme of the EU 7th Framework Programme (RAE no: PIIF-GA-2013-624904) and was supported by an EPSRC IKC Proof of Concept Award

The Intrinsic Dimensionality of Attractiveness: A Study in Face Profiles

The study of human attractiveness with pattern analysis techniques is an emerging research field. One still largely unresolved problem is which are the facial features relevant to attractiveness, how they combine together, and the number of independent parameters required for describing and identifying harmonious faces. In this paper, we present a first study about this problem, applied to face profiles. First, according to several empirical results, we hypothesize the existence of two well separated manifolds of attractive and unattractive face profiles. Then, we analyze with manifold learning techniques their intrinsic dimensionality. Finally, we show that the profile data can be reduced, with various techniques, to the intrinsic dimensions, largely without loosing their ability to discriminate between attractive and unattractive face

Phase Transitions in a Forest-Fire Model

We investigate a forest-fire model with the density of empty sites as control parameter. The model exhibits three phases, separated by one first-order phase transition and one 'mixed' phase transition which shows critical behavior on only one side and hysteresis. The critical behavior is found to be that of the self-organized critical forest-fire model [B. Drossel and F. Schwabl, Phys. Rev. Lett. 69, 1629 (1992)], whereas in the adjacent phase one finds the spiral waves of the Bak et al. forest-fire model [P. Bak, K. Chen and C. Tang, Phys. Lett. A 147, 297 (1990)]. In the third phase one observes clustering of trees with the fire burning at the edges of the clusters. The relation between the density distribution in the spiral state and the percolation threshold is explained and the implications for stationary states with spiral waves in arbitrary excitable systems are discussed. Furthermore, we comment on the possibility of mapping self-organized critical systems onto 'ordinary' critical systems.Comment: 30 pages RevTeX, 9 PostScript figures (Figs. 1,2,4 are of reduced quality), to appear in Phys. Rev.

Detecting the (Quasi-)Two-Body Decays of τ\tau Leptons in Short-Baseline Neutrino Oscillation Experiments

Novel detector schemes are proposed for the short-baseline neutrino experiments of next generation, aimed at exploring the large-$\Delta m^2$ domain of \omutau oscillations in the appearance mode. These schemes emphasize good spectrometry for charged particles and for electromagnetic showers and efficient reconstruction of \ypi_gg decays. The basic elements are a sequence of relatively thin emulsion targets, immersed in magnetic field and interspersed with electronic trackers, and a fine-grained electromagnetic calorimeter built of lead glass. These elements act as an integral whole in reconstructing the electromagnetic showers. This conceptual scheme shows good performance in identifying the $\tau$ (quasi-)two-body decays by their characteristic kinematics and in selecting the electronic decays of the $\tau$.Comment: 34 pages, 8 figure

Observation of a baryon resonance with positive strangeness in K+ collisions with Xe nuclei

The status of our investigation of low-energy $K^+$Xe collisions in the Xenon bubble chamber DIANA is reported. In the charge-exchange reaction $K^+Xe \to K^0 p Xe'$ the spectrum of $K^0 p$ effective mass shows a resonant enhancement with $M = 1539 \pm 2$ MeV/c$^2$ and $\Gamma \le 9 MeV/c$^2$. The statistical significance of the enhancement is near$4.4\sigma$. The mass and width of the observed resonance are consistent with expectations for the lightest member of the anti-decuplet of exotic pentaquark baryons, as predicted in the framework of the chiral soliton model.Comment: 9 pages, 4 figure