Aptidão agrícola das terras do Brasil: potencial de terras e análise dos principais métodos de avaliação.

O conhecimento da aptidão de terras e fator de grande importância para propiciar o uso adequado da oferta ambiental e, sobretudo, evitar possível sobreutilização dos recursos naturais. Fundamentalmente, este estudo foi realizado com o objetivo de oferecer uma visão sinóptica sobre o potencial agrícola e disponibilidade das terras do Brasil, bem como apresentar uma analise critica sobre os principais métodos e sistemas de avaliação da aptidão das terras. Este documento e o resultado da consolidação dos estudos básicos para o planejamento agrícola das terras de cada Estado da Federação, realizadas pelo Ministério da Agricultura, através da Secretaria Nacional de Planejamento - SUPLAN - entre 1977 e 1980. Não obstante o nível generalizado dos dados utilizados, foram interpretados os mais atualizados levantamentos de solos realizados no pais. O estudo fornece subsidio para projetar e dimensionar a oferta potencial de terras para atender a uma demanda, também projetada, de produtos agrícolas. O método utilizado foi o "sistema de avaliação da aptidão agrícola das terras", preconizado pela EMBRAPA Solos, no qual são adotados três níveis de manejo (níveis de tecnologia), visando diagnosticar o comportamento das terras em níveis operacionais distintos.bitstream/item/36134/1/Aptidao-agricula.pd

A parameter for quantitative analysis of plasticity induced crack closure

Numerical models have been successfully developed to predict plasticity induced crack closure (PICC). However, despite the large research effort a full understanding of the links between physical parameters, residual plastic wake and PICC has not been achieved yet. The plastic extension of material behind crack tip, Δyp, obtained by the integration of vertical plastic deformation perpendicularly to crack flank, is proposed here to quantify the residual plastic field. The values of Δyp and PICC were obtained numerically in a M(T) specimen using the finite element method. An excellent correlation was found between PICC and Δyp which indicates that this parameter controls the phenomenon, and can be used to quantify the effect of physical parameters. An empirical model was developed to predict PICC assuming that the residual plastic field is a set of vertical plastic wedges, that the linear superposition principle applies and that the influence of a particular wedge exponentially decreases with distance to crack tip. The model was applied successfully to predict PICC for different residual plastic fields which provided an additional validation of Δyp as the parameter controlling PICC

Simulation of crack growth in residual stress fields of pre-fatigued T-welded joints repaired by tungsten inert gas: a 3D approach

In this article, a three-dimensional finite element model (FEM) is used to predict the crack growth at the weld toe of a pre-fatigued T-joint that was repaired with a remelting technique. The numerical models were developed using the MSC.Marc software. Fatigue life is estimated by integrating the Paris-Erdogan law. The stress intensity factors are obtained by the virtual crack closure technique (VCCT). The T-welded joints, made of S355 steel, are obtained by covered electrode process and pre-cracked by fatigue. These welded joints were repaired by TIG dressing. The stress field generated by this dressing technique was estimated using a FEM model, presented in authors’ previous works. For the crack growth was used the VCCT three-dimensional model recently presented by the authors to predict the effect of overloads. The pre-existence of an elliptical crack at the weld toe, with a depth of 0.5 mm was considered. It is also studied the growth of pre-existing cracks which have been poorly repaired. It was observed that the TIG dressing produce residual compression stress fields on the weld toe that causes a delay in crack growth. The obtained results are compared with experimental ones. The fatigue’s lives obtained by simulations with the numerical model presented in this paper allows to evaluate the application conditions of TIG remelting technique in the repair of pre-cracked welded joints.info:eu-repo/semantics/publishedVersio

Melhoramento genético, registro e proteção de cultivares de Coffea canephora para o Estado de Rondônia.

O melhoramento genético do Coffea canephora objetivando a seleção de genótipos de ‘Conilon’ e ‘Robusta’ mais produtivos, tolerantes aos principais patógenos e adaptados às condições edafoclimáticas da região é de grande importância para impactar a cadeia produtiva do café no Estado de Rondônia. Tão importante quanto a obtenção da cultivar, é o seu registro e/ou proteção. Todas essas etapas fazem parte do processo de desenvolvimento e lançamento da cultivar, para que a mesma seja disponibilizada aos agricultores.bitstream/item/57882/1/doc143-cafe.pd

Discriminating among the theoretical origins of new heavy Majorana neutrinos at the CERN LHC

A study on the possibility of distinguishing new heavy Majorana neutrino models at LHC energies is presented. The experimental confirmation of standard neutrinos with non-zero mass and the theoretical possibility of lepton number violation find a natural explanation when new heavy Majorana neutrinos exist. These new neutrinos appear in models with new right-handed singlets, in new doublets of some grand unified theories and left-right symmetrical models. It is expected that signals of new particles can be found at the CERN high-energy hadron collider (LHC). We present signatures and distributions that can indicate the theoretical origin of these new particles. The single and pair production of heavy Majorana neutrinos are calculated and the model dependence is discussed. Same-sign dileptons in the final state provide a clear signal for the Majorana nature of heavy neutrinos, since there is lepton number violation. Mass bounds on heavy Majorana neutrinos allowing model discrimination are estimated for three different LHC luminosities.Comment: 7 pages, 5 figure