OPERATING PROPERTIES OF EPOXY COMPOSITIONS UNDER THE INFLUENCE OF ABSORPTION-ACTIVE ENVIRONMENT

e article examines the effect of providing the necessary physical, mechanical and operational characteristics of the road pavement material from cement concrete intended for highways. Studies carried out in this area have shown that the technical, economic and operational characteristics of such coatings are largely due to the rational choice of the material composition. In the author's proposed work, a study was made of the effect of durability under compression (fck.cube) and on bending (fctk) and abrasion (G). Changes in these characteristics are achieved by introducing into the cement concrete plasticizer (Dynamon Easy 11), filler (microsilica) and polypropylene fiber (MAPEFIBRE NS 12/ NS 18). The obtained researches made it possible to draw a conclusion that, with rational selection, the composition significantly increases the physico-mechanical and operational characteristics of the material of the pavement from cement concrete

Highly resolved WRF-BEP/BEM simulations over Barcelona urban area with LCZ

Unidad de excelencia María de Maeztu CEX2019-000940-MThis study evaluates the performance of urban schemes integrated in the Weather Research and Forecasting model (WRF) using Local Climate Zones (LCZ) as land use classification. We applied two multi-layer urban schemes: 1) Building Effect Parameterization (BEP) and 2) Building Energy Model coupled with BEP (BEP + BEM), over the Metropolitan Area of Barcelona (MAB) at 1km2 horizontal resolution for July 2016. These two simulations were compared with observations and a standard WRF simulation (BULK approach). Corine Land Cover 2012 provides background information for the entire simulation domain, while the LCZ covers MAB classifying the land cover into 10 classes according to urban morphology and thermal properties. BULK and multi-layer urban scheme experiments present a similar general error trend: overestimation of relative humidity and planetary boundary layer height and underestimation of temperature. Although BEP has the best correlation with observations, this is the scheme with the highest value of bias and RMSE for temperature and relative humidity, in particular during the night/morning. On the other hand, BEP + BEM performed with the minimum RMSE associated for temperature and relative humidity in the entire domain. BEP + BEM has shown to be more sensitive than the other schemes over locations where the land use in the model grid differs to the real one, which is a common consequent limitation of horizontal model resolution. This study also suggests that depending on the synoptic condition the scheme accuracy on determining PBLH might change considerably

On the validity of the reduced Salpeter equation

We adapt a general method to solve both the full and reduced Salpeter equations and systematically explore the conditions under which these two equations give equivalent results in meson dynamics. The effects of constituent mass, angular momentum state, type of interaction, and the nature of confinement are all considered in an effort to clearly delineate the range of validity of the reduced Salpeter approximations. We find that for $J\not{\hspace*{-1.0mm}=}0$ the solutions are strikingly similar for all constituent masses. For zero angular momentum states the full and reduced Salpeter equations give different results for small quark mass especially with a large additive constant coordinate space potential. We also show that $\frac{1}{m}$ corrections to heavy-light energy levels can be accurately computed with the reduced equation.Comment: Latex (uses epsf macro), 24 pages of text, 12 postscript figures included. Slightly revised version, to appear in Phys. Rev.

Bethe--Salpeter equation in QCD

We extend to regular QCD the derivation of a confining $q \bar{q}$ Bethe--Salpeter equation previously given for the simplest model of scalar QCD in which quarks are treated as spinless particles. We start from the same assumptions on the Wilson loop integral already adopted in the derivation of a semirelativistic heavy quark potential. We show that, by standard approximations, an effective meson squared mass operator can be obtained from our BS kernel and that, from this, by ${1\over m^2}$ expansion the corresponding Wilson loop potential can be reobtained, spin--dependent and velocity--dependent terms included. We also show that, on the contrary, neglecting spin--dependent terms, relativistic flux tube model is reproduced.Comment: 23 pages, revte

Confining Bethe--Salpeter equation in QCD

We derive a confining $q \bar{q}$ Bethe--Salpeter equation starting from the same assumptions on the Wilson loop integral already adopted in the derivation of a semirelativistic heavy quark potential. We show that, by standard approximations, an effective meson squared mass operator can be obtained from our BS kernel and that, from this, by ${1\over m^2}$ expansion, the corresponding Wilson loop potential is recovered, spin--dependent and velocity--dependent terms included. We also show, that, on the contrary, neglecting spin--dependent terms, relativistic flux tube model is reproduced.Comment: 5 pages, Latex, talk given at the workshop CONFINEMENT95, 22-24 March, Osak

On the instantaneous Bethe-Salpeter equation

We present a systematic algebraic and numerical investigation of the instantaneous Bethe-Salpeter equation. Emphasis is placed on confining interaction kernels of the Lorentz scalar, time component vector, and full vector types. We explore stability of the solutions and Regge behavior for each of these interactions, and conclude that only time component vector confinement leads to normal Regge structure and stable solutions.Comment: Latex (uses epsf macro), 26 pages of text, 12 postscript figures included

QCDOC: A 10-teraflops scale computer for lattice QCD

The architecture of a new class of computers, optimized for lattice QCD calculations, is described. An individual node is based on a single integrated circuit containing a PowerPC 32-bit integer processor with a 1 Gflops 64-bit IEEE floating point unit, 4 Mbyte of memory, 8 Gbit/sec nearest-neighbor communications and additional control and diagnostic circuitry. The machine's name, QCDOC, derives from ``QCD On a Chip''.Comment: Lattice 2000 (machines) 8 pages, 4 figure

A consistent derivation of the quark--antiquark and three quark potentials in a Wilson loop context

In this paper we give a new derivation of the quark-antiquark potential in the Wilson loop context. This makes more explicit the approximations involved and enables an immediate extension to the three-quark case. In the $q\overline{q}$ case we find the same semirelativistic potential obtained in preceding papers but for a question of ordering. In the $3q$ case we find a spin dependent potential identical to that already derived in the literature from the ad hoc and non correct assumption of scalar confinement. Furthermore we obtain the correct form of the spin independent potential up to the $1/m^2$ order.Comment: 30 pages, Revtex (3 figures available as hard copies only), IFUM 452/F