The determination of friction-coefficients of water in small iron pipes

This thesis was undertaken to determine accurately the coefficients of friction of water, flowing at varying velocities in small iron pipes and elbows. It was the intention to obtain the condition of pipes and elbows similar to that met with in general practice --Introduction, page 1

Is Brazilian rice immune to shocks?

This paper aimed to analyze the behavior of the Brazilian rice market in the face of exogenous shocks. Therefore, time series of exports, imports and prices received by farmers in Brazil from January 1997 to October 2019 were used to estimate the fractional differentiation parameter Gaussian Semiparametric Estimator (GSE), based on the frequency domain Whittle Function. Brazilian rice market is persistent to external shocks, with the presence of long memory in exports, imports and prices received by farmers

Silica grain catalysis of methanol formation

The specific catalytic effect of a silica grain on the formation of methanol via the sequential addition of H atoms to CO adsorbed on the surface is investigated. A negatively charged defect on a siliceous edingtonite surface is found to reduce the gas phase barriers for the H + COads and H + H2C=O-ads reactions by 770 and 399 K, respectively, when compared to the same reactions in the gas phase. The catalytic effect of negatively charged surface sites could also be applicable to the hydrogenation of other adsorbed unsaturated species. However, the activation energies on the surface defect are still too large (1150 and 2230 K) for CH3OH to form efficiently at 10-20 K in the interstellar medium via a classical mechanism. It is therefore suggested that quantum mechanical tunnelling through the activation barrier is required for these hydrogen addition reactions to proceed at such temperatures. The calculations show that because the adsorption energies of CO and H2C=O on the negatively charged defect are substantial, CH3OH may form efficiently during the warm-up period in star-forming regions

Dichotomy between urban and rural areas: statistical data may not reveal the synergy between these two existing spaces.

An analysis of several indicators, socio-economic and environmental, through the Dashboard of Sustainability is possible to tell which category has the highest rate of farmer sustainability, whether smallholders or monoculture. However, the secondary data available in Brazil today does not support a thorough analysis of the participation of each actor and to which the interconnection between the actors and their synergy in local economic activity. Since, given the narrowing between urban and rural, the statistical data available are not able to demonstrate the extent to which gives the rural-urban dichotomy. Thus, it is relevant to point out and discuss ways to provide consistent statistical data and be, in fact, able to demonstrate the local reality of a region within the welfare actors.ICAS 2013

Melhorias na gestão da propriedade rural: uma atualização do caso da bacia leiteira oeste Goiano frente ao cenário contemporâneo.

O objetivo deste artigo é identificar as deficiências na transferência de informações para pequenos produtores de leite. O acesso a informação é fator de desenvolvimento e crescimento de uma nação, sua carência inviabiliza a gestão de qualquer negócio. Atualmente, a quantidade de informação disponível é significativa, embora nem sempre a informação necessária seja recebida corretamente pelo usuário. As estratégias de transferência da informação são direcionadas principalmente para identificar qual e que tipo de informação poderá ajudar a atingir o objetivo proposto; a quem deverá ser entregue a informação e quais tecnologias deverão ser utilizadas. Mas a preocupação com a forma e com o momento adequado de apresentação da informação em relação a cada tipo de cultura é uma das estratégias mais importantes em qualquer processo de transferência. Os produtores de leite, por exemplo, possuem uma cultura que os diferencia de outras. O método utilizado para o levantamento dos dados foi o estudo de caso. Os dados da pesquisa realizada pelo Sebrae Goiás para o Projeto de Desenvolvimento Lácteo da Bacia Leiteira Oeste Goiano foram analisados e os resultados evidenciam carência de informação adequada aos produtores de leite. Como solução apresenta-se a metodologia chamada de "Treino e Visita" (T&V) que tem como característica a interatividade. O sistema consiste exatamente no fortalecimento das relações entre o técnico (a assistência técnica), a informação (a pesquisa agropecuária) e os produtores.Organizadores: Josealdo Tonholo e Vanusa Leitoguinho de Sá

Avaliação econômica de sistemas de produção de arroz irrigado em regiões selecionadas do Rio Grande do Sul, safras 2007/2008 a 2009/2010.

O presente trabalho objetivou o levantamento e avaliação da viabilidade dos Sistemas de produção modais de arroz irrigado praticados na Fronteira Oeste e na região Sul do RS

First-principles study of the polar O-terminated ZnO surface in thermodynamic equilibrium with oxygen and hydrogen

Using density-functional theory in combination with a thermodynamic formalism we calculate the relative stability of various structural models of the polar O-terminated (000-1)-O surface of ZnO. Model surfaces with different concentrations of oxygen vacancies and hydrogen adatoms are considered. Assuming that the surfaces are in thermodynamic equilibrium with an O2 and H2 gas phase we determine a phase diagram of the lowest-energy surface structures. For a wide range of temperatures and pressures we find that hydrogen will be adsorbed at the surface, preferentially with a coverage of 1/2 monolayer. At high temperatures and low pressures the hydrogen can be removed and a structure with 1/4 of the surface oxygen atoms missing becomes the most stable one. The clean, defect-free surface can only exist in an oxygen-rich environment with a very low hydrogen partial pressure. However, since we find that the dissociative adsorption of molecular hydrogen and water (if also the Zn-terminated surface is present) is energetically very preferable, it is very unlikely that a clean, defect-free (000-1)-O surface can be observed in experiment.Comment: 10 pages, 4 postscript figures. Uses REVTEX and epsf macro