A well simulator for homogeneous reservoirs based on formulations of the isogeometric boundary element method

The development of a simulator for homogeneous reservoirs with application in producer wells (represented by a sink) and the aquifer analysis is obtained by combining the Boundary Element Method (BEM), the Isogeometric Formulation using NURBS (Non Uniform Rational B-Spline) as shape functions, and also the Axisymmetric Formulation. The Isogeometric Formulation makes the discretization of geometric model (mesh generation), which is the step of numerical analysis that is more time consuming for the engineer, be no longer necessary, since the same functions that describe the geometry also approximate the field variables in the BEM. In other words, the same discretization used in the geometric model, generated in CAD (Computer Aided Design) modeling programs, also is used by the BEM. The oil and water reservoirs, as simplified models for validation of the new mathematical methodology, can be fully represented by the analysis of a plane passing through the axis of rotational (axial) symmetry. The dimension of the problem is reduced from three to two dimensions: radial and axial directions only, and all variables in the circumferential direction are assumed to be constant. When the geometry and the problem variables are both axisymmetric, then the problem is considered fully axisymmetric. The isogeometric and axisymmetric formulations are coupled to obtain the well simulator for the single and double phase case, i.e. one or two incompressible fluids inside the reservoir. The determination of boundary conditions for the model, including the analysis of fluids interface movement, is also presented. The final code is a new tool for the analysis of gas/water coning phenomenon and quick drawdown problem in homogeneous reservoirs, as validation models. Validation of the results is carried out by comparing with others numerical methods and analytical results

Bayesian analysis in the estimation of genetic correlations between visual scores and reproductive traits in Nelore cattle using linear-threshold models

Estimaram-se as correlações genéticas entre os escores visuais e as características reprodutivas, utilizando a estatística bayesiana sob modelo animal linear-limiar, em bovinos da raça Nelore. Foram estudadas características categóricas morfológicas, avaliadas visualmente aos oito, 15 e 22 meses de idade; e características contínuas de perímetro escrotal padronizado aos 365 e 450 dias de idade, além da idade ao primeiro parto. As estimativas de correlações genéticas foram de sentido favorável à seleção, apresentando magnitudes moderadas, sugerindo que a seleção de animais para um biótipo desejável pode levar a animais com maior fertilidade e precocidade sexual. As estimativas de correlação genética para o perímetro escrotal padronizado aos 450 dias e a idade ao primeiro parto com as características morfológicas avaliadas aos 22 meses de idade foram maiores do que as obtidas entre as características de escores visuais avaliadas aos oito e 15 meses de idade. A utilização de escores visuais como critério de seleção trará progresso genético também para as características reprodutivas.The genetic correlations between visual scores and reproductive traits, using the bayesian statistic under the linear-threshold animal model, in bovines of the Nelore breed were estimated. Categorical morphological traits were also evaluated at eight, 15, and 22 month-old, concerning musculature, physical structure, conformation and sacrum, the escrotal circumferences measured at the ages of 365 and 450-day-old, and the age at first calving. The estimates of genetic correlations were moderates, suggesting that the selection of animals with better morphological conformation may lead to animals more precocious and with greater fertility. The estimates of genetic correlation concerning the escrotal circumference at 450 day-old and the age at first calving with the evaluated visual scores at 22 month-old were higher than the ones obtained between visual scores at eight and 15 month-old. The use of these visual scores as a criterion of selection may also bring genetic progress to the reproductive traits

New hadrons as ultra-high energy cosmic rays

Ultra-high energy cosmic ray (UHECR) protons produced by uniformly distributed astrophysical sources contradict the energy spectrum measured by both the AGASA and HiRes experiments, assuming the small scale clustering of UHECR observed by AGASA is caused by point-like sources. In that case, the small number of sources leads to a sharp exponential cutoff at the energy E<10^{20} eV in the UHECR spectrum. New hadrons with mass 1.5-3 GeV can solve this cutoff problem. For the first time we discuss the production of such hadrons in proton collisions with infrared/optical photons in astrophysical sources. This production mechanism, in contrast to proton-proton collisions, requires the acceleration of protons only to energies E<10^{21} eV. The diffuse gamma-ray and neutrino fluxes in this model obey all existing experimental limits. We predict large UHE neutrino fluxes well above the sensitivity of the next generation of high-energy neutrino experiments. As an example we study hadrons containing a light bottom squark. These models can be tested by accelerator experiments, UHECR observatories and neutrino telescopes.Comment: 17 pages, revtex style; v2: shortened, as to appear in PR