Quantum spin chains with regularly alternating bonds and fields

We consider the spin-1/2 XY chain in a transverse field with regularly varying exchange interactions and on-site fields. In two limiting cases of the isotropic XX and extremely anisotropic (Ising) exchange interaction the thermodynamic quantities are calculated rigorously with the help of continued fractions. We discuss peculiarities of the low-temperature magnetic properties and a possibility of the spin-Peierls instability.Comment: Presented at 11-th Czech and Slovak Conference on Magnetism, Ko\v{s}ice, 20-23 August 200

Interfacial bond behaviour of GFRP bar in self-compacting fiber reinforced concrete

In an ongoing research project, discrete steel fibers are being used in a self-compacting concrete (SFRSCC) to replace completely steel stirrups for pre-fabricated beams reinforced longitudinally with pre-stressed glass fiber reinforced polymer (GFRP) and steel bars. To take the advantages of the non-corrodible character and high tensile strength of GFRP bars, the minimum SFRSCC cover needs to be determined in order to assure the adequate bond performance between these bars and the surrounding SFRSCC. Since bond of the longitudinal bars has a relevant impact on the cracking behavior of RC elements (crack opening and crack spacing), an extensive experimental program composed of pullout bending tests was carried out where the influence of the following parameters was assessed in terms of bond behavior: GFRP bar diameter, surface characteristics of the GFRP bars, bond length, SFRSCC cover thickness. The local bond law was derived from inverse analysis and it was used to define the slip mode of the constitutive law adopted for interface finite elements. These interface finite elements were used to assess the crack opening and crack spacing on SFRSCC beams flexurally reinforced with GFRP bars. This paper resumes the experimental program, describes the strategy to derive the local bond law and presents and discusses the numerical simulations

Thermodynamic properties of spin-1/2 transverse XY chain with Dzyaloshinskii-Moriya interaction: Exact solution for correlated Lorentzian disorder

We extend the consideration of the spin-1/2 transverse XY chain with correlated Lorentzian disorder (Phys. Rev. B {\bf 55,} 14298 (1997)) for the case of additional Dzyaloshinskii-Moriya interspin interaction. It is shown how the averaged density of states can be calculated exactly. Results are presented for the density of states and the transverse magnetization.Comment: 2 figure

The Domination Number of Grids

In this paper, we conclude the calculation of the domination number of all $n\times m$ grid graphs. Indeed, we prove Chang's conjecture saying that for every $16\le n\le m$, $\gamma(G_{n,m})=\lfloor\frac{(n+2)(m+2)}{5}\rfloor -4$.Comment: 12 pages, 4 figure

Influence of grease formulation on rolling bearings friction torque

lubricated with polymer greases at constant temperature. The tested greases were formulated with the same base oil (PAO) but different thickener content (polypropylene). The friction torque in rolling bearings produced by these greases was measured and the coefficients of friction under boundary and full film lubrication were numerically calculated through the approximation of the SKF friction torque model to the experimental results.The authors gratefully acknowledge the funding supported by: • National Funds through Fundação para a Ciência e a Tecnologia (FCT) under the projects PTDC/EME-PME/122271/2010 and EXCL/SEM-PRO/0103/2012; • COMPETE and National Funds through Fundação para a Ciência e a Tecnologia (FCT) under the project Incentivo/EME/LA0022/2014; • QREN: NORTE-07-0124-FEDER-000009 - Applied Mechanics and Product Development; without whom this work would not be possible

Scaling limits of a tagged particle in the exclusion process with variable diffusion coefficient

We prove a law of large numbers and a central limit theorem for a tagged particle in a symmetric simple exclusion process in the one-dimensional lattice with variable diffusion coefficient. The scaling limits are obtained from a similar result for the current through -1/2 for a zero-range process with bond disorder. For the CLT, we prove convergence to a fractional Brownian motion of Hurst exponent 1/4.Comment: 9 page

Characterization of suspension poly(vinyl chloride) resins and narrow polystyrene standards by size exclusion chromatography with multiple detectors: Online right angle laser-light scattering and differential viscometric detectors

This work reports the utilization of a multi-detector size chromatography for the characterization of poly(vinyl chloride) (PVC) resins prepared by suspension polymerization in the range of temperatures between 21 and 75 °C. The chromatography equipment offers the possibility of analyzing the samples in terms of their absolute molecular mass using a combination of three detectors (TriSEC): right angle light scattering (RALLS), a differential viscometer (DV) and refractive index (RI). The PVC resins were fully characterized concerning the molecular weight distribution (MWD), its dependence with intrinsic viscosity ([eta]) and molecular sizes (radius of gyration, Rg and hydrodynamic radius, Rh). Additionally, it is also presented the characterization of polystyrene narrow standards serving as reference polymers.http://www.sciencedirect.com/science/article/B6TWW-4HHGNVH-4/1/170871b80274a89470f2a790d3ed999

Application of GIS in potential beekeeping assessment: Case study of Montesinho Natural Park (Portugal)

Planners require solutions that address routine work needs and seems essential to improving efficiency and productivity. There are a great number of different factors related to beekeeper activity as well the quality and productivity of different bee products. The spatial analysis is a powerful tool for overlap and relates various levels of information on a map, and consequently a very useful for beekeeping activity planning. This work proposes and applies a methodology to potential beekeeping assessment in Montesinho Natural Park, a region in the northwest of Portugal. The beekeeping potential maps were developed with the following data sources: legal standards, vegetation, land use, topography, water resources, roads, electromagnetic fields, and some honey physico-chemical analysis. The design and implementation of spatial analysis model based on Geographic Information System (GIS) to beekeeping planning activities has already been described by Anjos et al (2014). Spatial analysis techniques allows to define the potential beekeeper map supporting the beekeeper management in this region. Anjos O, Silva G, Roque N, Fernandez P, 2014. GIS based analysis to support the beekeeping planning. Book of abstracts of the International Symposium on Bee Products 3rd edition – Annual meeting of the International Honey Commission (IHC), Faculty of medicine, University of Rijeka, p:6