Rational permutation groups containing a full cycle

A finite group whose irreducible complex characters are rational valued is called a rational group. Thus, G is a rational group if and only if N (G) (aOE (c) x >)/C (G) (aOE (c) x >) a parts per thousand OE Aut(aOE (c) x >) for every x a G. For example, all symmetric groups and their Sylow 2-subgroups are rational groups. Structure of rational groups have been studied extensively, but the general classification of rational groups has not been able to be done up to now. In this paper, we show that a full symmetric group of prime degree does not have any rational transitive proper subgroup and that a rational doubly transitive permutation group containing a full cycle is the full symmetric group. We also obtain several results related to the study of rational groups. (C) 2013 Mathematical Institute Slovak Academy of Science

Temperature and Weight Dependence of Free Volumes in Conducting Composite Polymer Using Positron Annihilation Techniques

Polyvinylidene fluoride-co-hexafluoropropylene (PVdF-co-HFP) with conducting polyaniline (PAni) was studied to measure free-volume intensity (I(3)), orthopositronium (o-Ps) lifetime (tau(3)), and Doppler momentum distribution parameters (S and W) as a function of temperature varying from 273 to 373 K and PAni weight percentage varying from 1 %-20 % using the techniques of Positron Annihilation Lifetime Spectroscopy (PALS) and Doppler Broadening Annihilation Radiation (DBAR). It has been observed that the free-volume intensity and the o-Ps lifetime increased sharply with PAni weight percentage up to 4 % after which decreased slowly. DBAR momentum distribution parameters behaved similarly as well and it's assumed that in the studied samples one-type defect was to exist. The thermal expansion coefficient also as a function of PAni weight was extracted from PALS data

A photogrammetric system design to determine the load-deflection behaviors of materials in civil engineering

WOS: 000296596400011This paper defines a photogrammetric system developed to automatically measure displacements at a large number of points on structural elements in static or quasi-static load experiments. The system consists of hardware and software. Basically, the hardware component includes online image acquisition system with three charge coupled device (CCD) cameras and the software comprises the photogrammetric processing of the obtained image data. The computational approach of the system involves initially determining the camera calibration parameters, then calculating three-dimensional (3D) object coordinates of signalized points on the test object during the load test. The measurements are performed in near real-time (<1 s), continuously for previously defined time periods or for a single measurement session after every loading by user intervention. For testing purposes, the system was used in the unconfined compression tests on different cohesive soil samples and load tests on a steel beam. Sub-millimeter object point precision was obtained for the 3D object coordinates in all the measurement sessions of both experiments. The axial deformations of cohesive soil samples were measured with a dial gauge and the comparison of the results obtained from both measurement systems indicated that the proposed photogrammetric system is sufficiently reliable and accurate to monitor the deflection behavior of materials under loading conditions

Rational permutation groups containing a full cycle

A finite group whose irreducible complex characters are rational valued is called a rational group. Thus, G is a rational group if and only if N (G) (aOE (c) x >)/C (G) (aOE (c) x >) a parts per thousand OE Aut(aOE (c) x >) for every x a G. For example, all symmetric groups and their Sylow 2-subgroups are rational groups. Structure of rational groups have been studied extensively, but the general classification of rational groups has not been able to be done up to now. In this paper, we show that a full symmetric group of prime degree does not have any rational transitive proper subgroup and that a rational doubly transitive permutation group containing a full cycle is the full symmetric group. We also obtain several results related to the study of rational groups. (C) 2013 Mathematical Institute Slovak Academy of Science

Improved direct methanol fuel cell performance of layer-by-layer assembled composite and catalyst containing membranes

The development of composite membranes and catalyst containing membranes (CCMs) with low methanol permittivity attracts a great deal of research attention for achieving higher performance in direct methanol fuel cells (DMFCs). Here, the fabrication and DMFC performance of composite and catalyst containing membranes (CCM) via layer-by-layer (lbl) technique are demonstrated. lbl composite and catalyst containing membrane based membrane-electrode assemblies (MEAs) show quite impressive cell performance. While the single cell performances of lbl composite membrane based MEAs are found to be in the range of 19.5 and 22 mW cm(-2), DMFC performance of MEA obtained from Pt containing self-assembled 10 bilayer of polyallylamine hydrochloride and polyvinylsulfonic acid, (PAH/PVS-H+)(10-pt), is found to be 24 mW cm(-2). This performance is nearly 65.5% higher compared to pure Nafion((R)) 112 based MEA. Inductive coupling plasma-mass spectroscopy (ICP-MS) result shows that Pt particles incorporate inside lbl multilayers with a loading of 0.28 mu gcm(-2). From the analyses of the performance evaluations, it is emphasized that the use of thin lbl catalyst containing membranes can be possible and quite promising in DMFC applications instead of thicker membranes due to their improved methanol barrier properties as well as proton conductivity. (c) 2013 Elsevier Ltd. All rights reserved

Influence of LbL surface modification on oxygen cross-over in self-assembled thin composite membranes

The paper is concerned with the investigation of oxygen transport in layer-by-layer (LbL) self assembly of polystyrene sulfonic acid sodium salt (PSS) and polyallylamine hydrochloride (PAH) on Nafion membrane depending on the number of deposited bilayers, ion type within the multilayers and temperature. It is observed from SEM analysis that the polyelectrolyte layers growth on each side of Nafion membrane regularly. The oxygen permeability (P-O2) of (PAH-PSS) 20 is 691 cm(3)/(m(2) day bar) at 25 degrees C while P-O2 of pristine Nafion is 2329 cm(3)/(m(2) day bar) at the same temperature. This significant reduction (70.3%) in gas permeability can be explained by the formation of LbL multilayers which both restrict the mobility of gas through the polymer matrix and adjust gas solubility properties in conjunction with ion-dipole interaction between the polar phase of Nafion and the secondary ammonium groups of PAH. (PAH/PSS)(20)-Na+ and (PAH/PSS)(20)-H+ exhibit 64.4% and 52.3% reduction in oxygen permittivity at 25 degrees C in comparison with the pristine Nafion (R) 117, respectively, while the proton conductivities of these membranes are 106.9 and 136.9 mS/cm. Promisingly, it is found that the membrane selectivity values (Phi) of all multilayered membranes in both H+ and Na+ form are much higher than that of perfluorosulfonated ionomer. The thickness of deposited bilayers dominates the diffusion and solubility properties of oxygen through the composite membrane while the major effect of surface hydrophilicity is not observed on oxygen permeability. (C) 2011 Elsevier B. V. All rights reserved