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Search Results: 1 - 10 of 205123 matches for " Kléber P.;Guerra "
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Desempenho de um trator agrícola equipado com pneus radiais e diagonais com três níveis de lastros líquidos
Monteiro, Leonardo de A.;Lan?as, Kléber P.;Guerra, Saulo P. S.;
Engenharia Agrícola , 2011, DOI: 10.1590/S0100-69162011000300015
Abstract: the correct use of tires, as for its construction type as for internal pressure calibration and the optimal weighting for each load condition are factors that impact significantly on their performance. this study aimed to compare the performance of a tractor equipped with radial tires and bias ply tires in three conditions of liquid ballast (0%, 40% and 75% water), three surface conditions of a dystrophic red alfisol (firm surface, tillage surface and surface with corn residues coverage) and three theoretical traveling speeds (4 km h-1, 5 km h-1 and 7 km h-1), as indicated at the tractor display, related to the gear boxes b1, b2 and c1. the best tractor's performance, equipped with bias ply tire happened at 75% water in the tires and it had provide a higher traveling speed, lower slippage, lower fuel consumption per hour and higher drawbar pull power. the radial tires with the best performance happened at 40% water in tires and it has provided a higher traveling speed, lower slippage, lower fuel consumption per hour, lower specific fuel consumption and higher drawbar pull power bar.
UMEB - Unidade Móvel para Ensaio da Barra de Tra??o
Gabriel Filho, Antonio;Lan?as, Kléber P.;Guerra, Saulo P.;Paula, Cristiano A.;Monteiro, Leonardo A.;
Engenharia Agrícola , 2008, DOI: 10.1590/S0100-69162008000400018
Abstract: a "mobile drawbar test unit - umeb" was developed at fca/unesp, botucatu -sp, brazil, to evaluate tractor performance in agricultural soil. the umeb was built from a road trailer adapted to serve as load car used in draw bar tractor test. its total mass is 10,500 kg sustained by a group of six pneumatic wheels. field test showed that the umeb generated traction force up to 35 kn, keeping it constant in different soil surface conditions, even when the forward speed changes.
Resistência do solo à penetra??o, após o tráfego com dois tipos de pneus utilizando-se um equipamento para ensaio dinamico
Nagaoka, Alberto K.;Lan?as, Kléber P.;Castro Neto, Pedro;Lopes, Afonso;Guerra, Saulo P. S.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2003, DOI: 10.1590/S1415-43662003000200034
Abstract: the main objective of this research was to evaluate the soil cone index results as a function of tyre type (radial and bias tyres) and tyre load using a single wheel testing equipment and verifying the effect on the layers after tyre traffic. this equipment was projected for linking at the rear of a tractor and was activated by the power with the purpose of testing individual tyre under field conditions and constituted of a mechanical transmission box and electronic instruments of measurement. this study was conducted at the agricultural tyre testing center - nempa of rural engineering department, faculty of agronomic sciences, unesp, botucatu, sp. the data obtained were analyzed considering a random block experimental design in split plot with tyre in the main plot (radial and bias tyres) and tyre load (10.000 n, 13.000 n, 16.000 n and 19.000 n) in the split plots with five repetitions. the radial tyre showed advantage in relation to bias tyre showing small cone index values. the highest loads provoked largest cone index values and its increments in the layers of 0 to 10 cm and 10 to 20 cm.
Avalia??o do contato pneu-solo em três modelos de pneus agrícolas
Mazetto, Flávio R.;Lan?as, Kléber P.;Nagaoka, Alberto K.;Castro Neto, Pedro;Guerra, Saulo P. S.;
Engenharia Agrícola , 2004, DOI: 10.1590/S0100-69162004000300028
Abstract: the aim of this study was to evaluate the tire/ground contact areas, tire elastic deformation, cone index and foot printed on the ground of tire models. the experiment was done in 12 treatments and four repetitions with three tire models: bias ply, radial and bias belt. the tires were inflated with right inflation pressures and four radial loads were applied on the wheels: 5; 10; 15 and 20 kn, simulating what happens in the field. the agricultural tire tests were carried out at sao paulo state university, botucatu - sp, brazil, using a hydraulic press over the soil bin. the contact area and elastic deformation results showed highest values for bias belt tire. the soil sinkage of bias belt tire was smaller than other pneumatic tires. the radial and bias belt tires exercised smaller cone index than bias ply tire.
Influência da altura das garras dos pneus de um trator em área de plantio direto
Gabriel Filho, Antonio;Monteiro, Leonardo A.;Lan?as, Kléber P.;Guerra, Saulo P. S.;Jesuino, Paulo R.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2010, DOI: 10.1590/S1415-43662010001000015
Abstract: this work was carried out to evaluate the performance of a farm tractor fitted with two sets of tires with high lugs and another set of tires with tallow lugs in straw without tillage (corn straw). the travel speeds used were approximately 4, 5, 6 and 7 km h-1 and a constant pulling force of 25 kn was fixed. tractor traction, forward speed, slip and consumption of fuel were measured and drawbar power, the ratio between the consumption and power and traction coefficient were calculated. it was observed that the tractor performance was similar to high and low lug tire conditions, in an area covered with corn straw.
Agrega??o de ume nitossolo vermelho distroférrico sob sistemas de plantio direto, preparo convencional e mata nativa
Assis, Renato L. de;Lan?as, Kléber P.;
Engenharia Agrícola , 2010, DOI: 10.1590/S0100-69162010000100006
Abstract: this study aimed to evaluate the effect of time since the adoption of the no-till system, in comparison with a native forest area and a conventional tillage area, using the distribution of soil aggregates in a distroferric red nitosol. treatments were as follows: native forest (nf), conventional tillage (ct), no-till for one year (nt1), no-till for four years (nt4), no-till for five years (nt5), and no-till for 12 years (nt12). aggregate samples were collected randomly within each treatment at depths of 0-5 and 10-15 cm. after sifting the aggregates in water they were separated into the following aggregate classes > 2 mm; < 2 mm; 2-1 mm, and < 1 mm. the adoption time in the no-till system favored soil aggregation. the mean weighted diameter (mwd) of the soil aggregates and the percentage of aggregates greater than 2 mm increased with adoption time in the no-till system at the 0-5 cm depth. the nf and nt12 treatments had higher mwd values in the 0-5 cm layer. ct had the highest percentage of aggregates smaller than 1 mm.
Avalia??o da resistência do solo à penetra??o em diferentes solos com a varia??o do teor de água
Assis, Renato L. de;Lazarini, Gilmar D.;Lan?as, Kléber P.;Cargnelutti Filho, Alberto;
Engenharia Agrícola , 2009, DOI: 10.1590/S0100-69162009000400006
Abstract: as human population and demand for food grow, new technologies have emerged to increase productivity and reduce production costs. if these technologies on the one hand have increased production and reduced costs, on the other hand the intense traffic of machinery and tractors have modified the soil structure, causing compaction and compromising agricultural productivity. in this study we relate soil moisture to soil resistance to penetration in four soil types under four moisture conditions, using a hydraulic-electronic penetrometer containing a dgps navigation system. the results showed there were changes in the friction conditions between the cone and the soil as moisture increased, facilitating rod penetration and making the soil more plastic due to the lubricating action among its particles. the highest values of soil resistance to penetration were detected around the soil shrinkage limit. there was a negative correlation between cone index and moisture. the best fit for all soils was provided by a decreasing linear function, with high coefficients of determination. under higher soil moisture conditions, soil resistance to penetration values can be considered not to prevent root growth. soil type also had a significant impact on cone index results.
Consumo de combustível de um trator em fun??o do tipo de pneu, da lastragem e da velocidade de trabalho
Lopes, Afonso;Lan?as, Kléber P.;Furlani, Carlos E. A.;Nagaoka, Alberto K.;Castro Neto, Pedro;Grotta, Danilo Cesar C.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2003, DOI: 10.1590/S1415-43662003000200033
Abstract: the objective of this study was to compare the consumption of fuel of the fwd agricultural tractor, equipped with three types of tyres (bias ply, radial and low pressure), with and without tyre water ballasting, operating in four forward speeds. the research was carried out at fcav/unesp, sp, brazil, the soil was tilled using a chisel plow. a tractor with 89 kw (121 hp) engine power equipped with fwd was used in the experiment, and the tyres used had the following characteristics: radial (front: 14.9r26 and rear: 620/75r30), bias ply (front: 14.9-26 and rear: 23.1-30) and low pressure (front: 500/60-26.5 and rear: 700/55-34). the experiment was conducted in a completely randomized block design (3x2x4), with a total of 24 treatments and three replications. the results evidenced advantages for the tractor equipped with radial tyres. the ballasting condition with water in the tyres showed lower specific consumption. it was also observed that the increase of the forward speed reduced the specific consumption.
Sobre a Pesquisa Qualitativa na Modelagem Matemática em Educa??o Matemática
Klüber, Tiago Emanuel;Burak, Dionísio;
Bolema: Boletim de Educa??o Matemática , 2012, DOI: 10.1590/S0103-636X2012000300007
Abstract: research on mathematical modelling in mathematics education has been carried out in brazil for over three decades. in this period of time, it's possible to confirm that the qualitative research approach is predominant. in this context, we make explicit some meanings of qualitative research in mathematical modelling in mathematics education in brazil. some meanings are unraveled using a phenomenological approach to the question: how does qualitative research show itself in mathematical modelling in mathematics education? papers published in the iii international seminar for research in mathematics education - sipem, held in 2006, provide the basis for the discussion. the interpretations point to fragilities with respect to the usage of qualitative approach, mainly a lack of detailed descriptions of the procedures of the analysis, which need to be more broadly debated in order to contribute to progress in research in mathematical modelling in mathematics education.
A fenomenologia e suas contribui es para a Educa o Matemática
Tiago Emanuel Klüber,Dionísio Burak
Práxis Educativa , 2008,
Abstract: This paper intends to present our understanding in relation the phenomenology and its possibility of use as method of qualitative research. From this understanding, it presents some interpretations about its application to the Mathematics Education research field.
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