Tecnologias de aplicação de agrotóxicosPesquisas mostram que os avanços nas tecnologias de aplicação têm proporcionado melhor condução da calda ao alvo, em grande parte por diminuição da deriva, muitas vezes provocada pela necessidade de utilizar gotas pequenas, que apresentam melhor penetração no dossel das culturas. O desenvolvimento de novas tecnologias de aplicação de agrotóxicos visa à redução da contaminação ambiental, da deriva, do volume de calda, com aumento da segurança do aplicador e melhoria da deposição da calda, para melhor qualidade da pulverização. Palavras Pesticide application technologiesResearch has shown that progress in spraying technology has provided better delivery of the spray solution to the target, mostly by minimizing off-target drift, which is many times caused by the need of using small droplets, once they have better penetration in crop canopy. The development of new pesticide application technologies aim to reduce environmental contamination, off-target drift and spray volume, by improving the sprayer safety and spray deposition and consequently the spraying quality.
Resumo A concentração gravítica corresponde a uma das mais antigas e importantes formas de processamento mineral, sendo utilizada para beneficiar uma grande variedade de minérios. Neste contexto, a melhor maneira de investigar e prever resultados de processos gravíticos é a chamada "curva de lavabilidade". Estas curvas apresentam a distribuição das partículas de um dado um material segundo as suas densidades e são construídas a partir de dados experimentais obtidos nos denominados testes de flutua-afunda. Para a realização destes testes são utilizados líquidos com diferentes densidades, os quais correspondem a substâncias muito tóxicas, voláteis, de difícil manuseio e, na maioria dos casos, muito caras. Além disto, por não existirem líquidos com densidades muito elevadas, os mesmos não podem ser usados no fracionamento de sulfetos ou óxidos metálicos, o que restringe o uso das curvas de lavabilidade a materiais leves. Pensando nisto, procedeu-se ao desenvolvimento do presente trabalho, cujo objetivo é apresentar uma nova metodologia para a construção das curvas de lavabilidade a partir da análise de imagens digitais. Com esta metodologia será possível construir curvas de lavabilidade de uma maneira mais rápida e segura, além de tornar possível a aplicação desta ferramenta para minérios que possuam partículas com densidades mais elevadas. Palavras-chave: Beneficiamento mineral; Separação gravítica; Curvas de lavabilidade; Análise de imagens digitais. DETERMINATION OF WASHABILITY CURVES USING DIGITAL IMAGE ANALISYS Abstract The gravity concentration corresponds to one of the oldest and most important techniques of mineral processing and it is used to process a large variety of ores. In this context, the best way of investigating and predicting results of gravity concentration processes is "washability curve". This curve shows the distribution of particles of a given material according to their densities and it is constructed from experimental data obtained under ideal conditions in so-called sink-float tests. For performing these tests dense liquids with different densities are used, which correspond to very toxic, volatile, unwieldy and, in most cases, very expensive substances. Furthermore, because there are no dense liquids with very high densities, they cannot be used in fractionation of sulfides or metal oxides, which restricts the use of washability curves to lightweight materials. With this in mind, this work was developed. The objective here is to present a new methodology for the construction of the washability curves from digital image analysis. With this method it will be possible to build washability curves in a more quickly and safely way, making possible the application of this tool for ores having particles with higher densities.
ABSTRACT. The heavy traffic of machines in no-tillage systems causes problems as soil compaction and loss of crops productivity. The objective of this paper is to evaluate the productivity of soybeans in reference to furrow openers and the levels of soil compaction in two crops. The experiment was conducted on Rhodic Hapludox by tracing random blocks with subdivided parcels. The soil bulk density levels were laid out in the parcels (1.16, 1.20, 1.22, and 1.26 Mg m -3) and the furrowers in the sub-parcels (double disc and shanks). The resistance to penetration, depth of the furrow, mobilized soil area, final plant stands, height of plants, mean number of beans by pod, 1,000 bean mass, number of pods per plant and productivity of the culture were evaluated. The resistance to penetration increased with the levels of soil compaction regardless of the farming year and up to a depth of 0.20 m. In the first crop, higher productivity with the use of the shank was observed. In the second crop, the use of the shank resulted in an increase in depth of the furrow, mobilized soil, height of the plants and final stand of the plants, but this did not indicate an increase in productivity.
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