Sofia University

About: Sofia University is a education organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Large Hadron Collider & Laser. The organization has 8533 authors who have published 15730 publications receiving 306320 citations. The organization is also known as: University of Sofia & BFUS.

Neural Networks for Online Classification of Hand and Finger Movements Using Surface EMG signals

Abstract: Myoelectric signals (MES) are the electrical manifestation of muscular contractions and they can be used to create myoelectric prosthesis which are able to function with the amputee's muscle movements. This signal recorded at the surface of the skin of the forearm has been exploited to provide recognition of the movement of the hand and finger Movements of healthy subject. The objective of the paper is to describe the identification procedure, based on EMG patterns of forearm activity using various Neural Networks methods and to make a comparison between different intelligent computational methods of identification, which are used in this work. Then an online algorithm for movement identification and classification that utilises the trained Neural Networks is presented.

Event activity dependence of Υ(nS) production in √sNN = 5.02 TeV pPb and √s = 2.76 TeV pp collisions

Abstract: The production of Y(1S), Y(2S), and Y(3S) is investigated in pPb and pp collisions at centre-of-mass energies per nucleon pair of 5.02 TeV and 2.76 TeV, respectively. The datasets correspond to integrated luminosities of about 31 inverse nanobarns (pPb) and 5.4 inverse picobarns (pp), collected in 2013 by the CMS experiment at the LHC. Upsilons that decay into muons are reconstructed within the rapidity interval abs(y[CM]) , are found to rise with both measures of the event activity in pp and pPb. In both collision systems, the ratios of the excited to the ground state cross sections, Y(nS)/Y(1S), are found to decrease with the charged-particle multiplicity, while as a function of the transverse energy the variation is less pronounced. The event activity integrated double ratios, [Y(nS)/Y(1S)][pPb] / [Y(nS)/Y(1S)][pp], are also measured and found to be 0.83 +/- 0.05 (stat.) +/- 0.05 (syst.) and 0.71 +/- 0.08 (stat.) +/- 0.09 (syst.) for Y(2S) and Y(3S), respectively.

Water Chemistry on Model Ceria and Pt/Ceria Catalysts

Abstract: We have studied the interaction of water with stoichiometric CeO2(111)/Cu(111), partially reduced CeO2–x/Cu(111), and Pt/CeO2/Cu(111) model catalysts by means of synchrotron–radiation photoelectron spectroscopy (SRPES), resonant photoemission spectroscopy (RPES) at the Ce 4d edge, infrared reflection absorption spectroscopy (IRAS), and density functional (DF) calculations. The principal species formed during adsorption of water at 160 K on CeO2(111) films is chemisorbed molecular water. On the surface of CeO2–x water partially dissociates yielding hydroxyl groups. By use of core-level PES, differentiation between chemisorbed water and hydroxyl groups is complicated by the overlap of the corresponding spectral features. Nevertheless, we determined three characteristic indicators for OH groups on ceria: (i) the presence of 1π and 3σ states in valence band (VB) PES; (ii) an increase of the binding energy (BE) separation between the O 1s spectral components of lattice oxygen and OH/H2O; (iii) an increase of t...

Pultrusion of a flax/polypropylene yarn

Abstract: The present work reports the pultrusion of a flax reinforced polypropylene commingled yarn containing discontinuous flax and polypropylene fibers. This was the first attempt to pultrude this material. Rectangular cross-sectional profiles have been successfully produced using a self-designed pultrusion line. In a series of experiments carried out with yarns of two different flax fiber contents, the pultrusion parameters were varied. In particular, the preheating and die temperatures and also the pulling speed, which are the most relevant parameters regarding the potential future pultrusion of natural fiber composite profiles at industrial scale. A complete characterization of each profile was conducted in order to examine the influence of processing parameters on the profile quality. The mechanical properties were evaluated by performing three point bending as well as Charpy impact tests.