Papers by Alessandro Rodrigues
Revista Brasileira de Fruticultura, 2010
RESUMO -A produção de uvas de mesa é uma importante atividade econômica no Estado de São Paulo. A... more RESUMO -A produção de uvas de mesa é uma importante atividade econômica no Estado de São Paulo. A região de Porto Feliz, em clima Cwa, apresenta grande número de agricultores familiares dedicados a esta atividade. Condições climáticas e manejo da cultura durante a fase de amadurecimento determinam a qualidade dos bagos, sendo o uso de fitorreguladores uma ferramenta útil para o ajustamento de atributos da qualidade. Avaliaram-se sete concentrações de ethephon, aplicadas por imersão dos cachos no início da mudança de coloração dos bagos, sobre a qualidade de uva 'Rubi', durante os ciclos de 2007 e de 2008, em propriedade comercial localizada em Porto Feliz-SP. Os atributos de qualidade avaliados foram a coloração de bagos, teor de sólidos solúveis totais e desbagoamento pós-colheita, sendo determinado também o índice de velocidade de desbagoamento. Os dados coletados foram submetidos à análise de variância e de regressão. Em 2007, observaram-se maiores coloração e teor de sólidos solúveis totais, associados às maiores temperaturas registradas no período entre o início de maturação e a colheita. O uso de ethephon, independentemente da concentração utilizada, promoveu coloração mais avermelhada dos bagos de 'Rubi' nas duas safras. Não houve efeito do uso do ethephon sobre o teor de sólidos solúveis totais. Não foi possível inferir sobre o efeito do etephon no desbagoamento em função do elevado coeficiente de variação. Estudos básicos para avaliar o efeito de fatores climáticos, nutricionais e de manejo do vinhedo são necessários no desenvolvimento de coloração dos bagos da cultivar 'Rubi' em clima tropical. Termos para indexação: coloração, regulador de crescimento vegetal, sólidos solúveis, Vitis vinifera L.
Rendimento de uva 'Niagara Rosada' submetida à redução de área foliar
Revista Brasileira de Fruticultura, 2010
RESUMO-O objetivo deste trabalho foi verificar o efeito da perda da área foliar da videira, no pe... more RESUMO-O objetivo deste trabalho foi verificar o efeito da perda da área foliar da videira, no período compreendido entre a colheita ea queda natural das folhas, sobre o rendimento das safras futuras. Após colheita realizada em 15-12-2005, selecionaram-se plantas que ...
Citrus Research & Technology, 2013
Desenvolvimento do pessegueiro 'Flordaprince' sob duas intensidades de poda verde
Bragantia, 2009
'Flordaprince' peach [Prunus persica (L.) Batsch] was submitted to two levels of green pruning in... more 'Flordaprince' peach [Prunus persica (L.) Batsch] was submitted to two levels of green pruning intensity (mild and renewal), 45 days after harvest, with the objective of evaluating its effects on plant development, production, fruit quality and soluble carbohydrates in roots and branches. The experiment was carried out at University of São Paulo, Piracicaba, Brazil, in the 2003/2004 season. The experimental designed was entirely randomized, with two treatments and twelve replicates. Experimental unit comprised two plants at the 3,0 m x 1,2 m spacing and was conducted in central leader system. Biometric data collected were: effective flowering, sprouting, shoot length after green and winter pruning, quality and production of fruits, and soluble carbohydrates in roots and branches. Renewal pruning leads to lower soluble carbohydrate concentrations in the roots during dormancy. Renewal pruning also decreases fruit retention and Brix, even though it increases individual fruit weight. Green pruning intensities do not influence soluble carbohydrates concentration in branches, fruit growth or shoot growth after winter pruning. Soluble carbohydrate concentrations are always higher in the roots.
Intensidade de poda verde em pessegueiro para controle da ferrugem Tranzschelia discolor (Fuckel) Tranzschel e Litvinov
Revista Brasileira De Fruticultura, 2008
Rust [Tranzschelia discolor (Fuckel) Tranzschel and Litvinov] control in peach [Prunus persica (L... more Rust [Tranzschelia discolor (Fuckel) Tranzschel and Litvinov] control in peach [Prunus persica (L.) Batsch] cultivar 'Flordaprince' was evaluated through the use of two green pruning levels performed 45 days after harvest: light pruning and renovation pruning. Experimental works were conducted at University of São Paulo, Piracicaba-SP, Brazil, from November 2004 to January 2005. Experimental design was completely randomized with two treatments and 12 replicates. Experimental unit was comprised of two plants under central leader's system in a high density orchard (2777 trees ha-1). Incidence (% of diseased leaves) and severity (% of lesioned leaf area) were evaluated weekly from 33 to 81 days after green pruning in four shoots per experimental unit. Data were submitted to Fisher's Exact Test (rust incidence) and Wilcoxon's Test (rust severity). Rust lesions increased with leaf age regardless of pruning level. Rust incidence and severity were, respectively, 81, 95% of diseased leaves and 1,43% of lesioned leaf area, 81 days after green pruning. Renovation pruning did not decrease rust leaf lesions in 'Flordaprince' peach from 40 to 81 days after green pruning.
International Journal of Biometeorology, 2012
Plant growth and development are proportional to biological time, or the thermal time of the spec... more Plant growth and development are proportional to biological time, or the thermal time of the species, which can be defined as the integral of the temperature over time between the lower and upper temperature developmental thresholds. The objective of this study was to investigate the efficiency of the growing degree-day (GDD) approach for vines of the 'Niagara Rosada' cultivar pruned in winter and summer seasons, and physiological phases (mobilisation and reserve accumulation) in a humid subtropical region. The experiment was carried out on 13-year-old plants in Piracicaba, São Paulo State-Brazil, evaluating 24 production cycles, 12 from the winter pruning, and 12 from the summer pruning. The statistical design was comprised of randomised blocks, using the pruning dates as treatment: (summer). Comparison of the mean values of GDD among pruning dates was evaluated by the Tukey test, and comparison between pruning seasons was made by the F test for orthogonal contrasts, both at the 5% probability level. The results showed good agreement between the values of GDD required to complete the cycle from the winter pruning until harvest when compared with other studies performed with the same cultivar grown in the Southern and Southeastern regions of Brazil. However, there was a consistent statistical difference between GDD computed for winter and summer pruning, which allowed us to conclude that this biometeorological index is not sufficient to distinguish vines pruned in different seasons and physiological phases applied in humid subtropical climates.
Desenvolvimento do pessegueiro 'Flordaprince' sob duas intensidades de poda verde
Bragantia, 2009
'Flordaprince' peach [Prunus persica (L.) Batsch] was submitted to two le... more 'Flordaprince' peach [Prunus persica (L.) Batsch] was submitted to two levels of green pruning intensity (mild and renewal), 45 days after harvest, with the objective of evaluating its effects on plant development, production, fruit quality and soluble carbohydrates in roots and branches. The experiment was carried out at University of São Paulo, Piracicaba, Brazil, in the 2003/2004 season. The experimental designed was entirely randomized, with two treatments and twelve replicates. Experimental unit comprised two plants at the 3,0 m x 1,2 m spacing and was conducted in central leader system. Biometric data collected were: effective flowering, sprouting, shoot length after green and winter pruning, quality and production of fruits, and soluble carbohydrates in roots and branches. Renewal pruning leads to lower soluble carbohydrate concentrations in the roots during dormancy. Renewal pruning also decreases fruit retention and Brix, even though it increases individual fruit weight. Green pruning intensities do not influence soluble carbohydrates concentration in branches, fruit growth or shoot growth after winter pruning. Soluble carbohydrate concentrations are always higher in the roots.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2007
This paper presents specific cutting energy measurements as a function of the cutting speed and t... more This paper presents specific cutting energy measurements as a function of the cutting speed and tool cutting edge geometry. The experimental work was carried out on a vertical CNC machining center with 7,500 rpm spindle rotation and 7.5 kW power. Hardened steels ASTM H13 (50 HRC) were machined at conventional cutting speed and high-speed cutting (HSC). TiN coated carbides with seven different geometries of chip breaker were applied on dry tests. A special milling tool holder with only one cutting edge was developed and the machining forces needed to calculate the specific cutting energy were recorded using a piezoelectric 4-component dynamometer. Workpiece roughness and chip formation process were also evaluated. The results showed that the specific cutting energy decreased 15.5% when cutting speed was increased up to 700%. An increase of 1° in tool chip breaker chamfer angle lead to a reduction in the specific cutting energy about 13.7% and 28.6% when machining at HSC and conventional cutting speed respectively. Furthermore the workpiece roughness values evaluated in all test conditions were very low, closer to those of typical grinding operations (~0.20 µm). Probable adiabatic shear occurred on chip segmentation at HSC.
The International Journal of Advanced Manufacturing Technology, 2014
During micromachining, the interaction between the cutting tool and the workpiece material may ca... more During micromachining, the interaction between the cutting tool and the workpiece material may cause damages on the machined surface related to material deformation. It would be interesting that the workpiece microstructure suits the scale of the cutting parameters. Very little has been investigated on how a metallurgically modified material responds to microcutting. This research evaluated the effect of an ultrafine-grained material in the micromilling of grooves. Dual-phase low-carbon steel (ferrite-pearlite) was submitted to warm rolling for grain refinement (from 11-to 0.7-μm size of ferrite grains). The effect of tool cutting edge radius (r e ), feed per tooth (f t ), tool diameter, and speed cutting upon surface roughness and burr formation during end-milling of the original material and the modified one was evaluated. The ultrafine-grained material showed better results of surface finishing and presence of burrs when compared to the original dual-phase material. The metallurgical modification of lowcarbon steels by grain refinement favored for micromachining of grooves, making it possible to extend applications of this class of steels.
Fundamentals, Methods and Applications, 2012
This research estimated the temperature field in the cutting zone and compared it to the experime... more This research estimated the temperature field in the cutting zone and compared it to the experimental results when machining AISI 5135 steel applied in the automotive industry. The simulation was performed by employing ABAQUS/Explicit R version 6.10-1 which uses a finite element method for spatial discretization of momentum equation and an explicit integration scheme for discretization relative to time. Through this numerical technique various machining parameters can be predicted such as force and temperature. A 2D orthogonal cutting has been modeled using Arbitrary Lagrangian-Eulerian (ALE formulation). The thermo-viscoplastic behavior of the workpiece material is modeled by Johnson-Cook constitutive work flow stress model. The numerical results presented a good agreement to the experimental ones validating them by an error of only ∼ 3%.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2010
This paper presents a study on the influence of milling condition on workpiece surface integrity ... more This paper presents a study on the influence of milling condition on workpiece surface integrity focusing on hardness and roughness. The experimental work was carried out on a CNC machining center considering roughing and finishing operations. A 25 mm diameter endmill with two cemented carbide inserts coated with TiN layer were used for end milling operation. Low carbon alloyed steel Cr-Mo forged at 1200 °C was used as workpiece on the tests. Two kinds of workpiece conditions were considered, i.e. air cooled after hot forging and normalized at 950 °C for 2 h. The results showed that finishing operation was able to significantly decrease the roughness by at least 46% without changing the hardness. On the other hand, roughing operation caused an increase in hardness statistically significant by about 6%. The machined surface presented deformed regions within feed marks, which directly affected the roughness. Surface finish behavior seems to correlate to the chip ratio given the decrease of 25% for roughing condition, which damaged the chip formation. The material removal rate for finishing operation 41% greater than roughing condition demonstrated to be favorable to the heat dissipation and minimized the effect on material hardness.
Materials Research, 2014
Grain size refinement is one of the most efficient strengthening mechanisms applied to modern Hig... more Grain size refinement is one of the most efficient strengthening mechanisms applied to modern High-Strength Low-Alloy steels (HSLA) because yield strength and toughness are both improved. This paper discusses the distribution of carbides by using transmission electron microscopy (TEM) in a low-carbon steel with ultrafine grained (UFG) ferrite. Fine cementite particles were formed during water quenching due to the auto-tempering of highly distorted martensite. Other fine particles observed under the same condition were nucleated due to the presence of carbide formers such as niobium, titanium and vanadium. TEM analysis showed that cementite particles underwent Ostwald ripening during warm rolling but they were still able to inhibit ferrite grain growth, which was maintained 1µm size approximately.
Journal of Materials Processing Technology, 2008
The present work shows an experimental and theoretical study on heat flow when end milling, at hi... more The present work shows an experimental and theoretical study on heat flow when end milling, at high-speed, hardened steels applied to moulds and dies. AISI H13 and AISI D2 steels were machined with two types of ball nose end mills: coated with (TiAl)N and tipped with PcBN. The workpiece geometry was designed to simulate tool–workpiece interaction in real situations found in mould industries, in which complex surfaces and thin walls are commonly machined. The compressed and cold air cooling systems were compared to dry machining. Results indicated a relatively small temperature variation, with higher range when machining AISI D2 with PcBN-tipped end mill. All cooling systems used demonstrated good capacity to remove heat from the machined surface, especially the cold air. Compressed air was the most indicated to keep workpiece at relatively stable temperature. A theoretical model was also proposed to estimate the energy transferred to the workpiece (Q ) and the average convection coefficient (h¯) for the cooling systems used. The model used a FEM simulation and a steepest decent method to find the best values for both variables.
Journal of The Brazilian Society of Mechanical Sciences and Engineering, 2010
This paper presents a study on the influence of milling condition on workpiece surface integrity ... more This paper presents a study on the influence of milling condition on workpiece surface integrity focusing on hardness and roughness. The experimental work was carried out on a CNC machining center considering roughing and finishing operations. A 25 mm diameter endmill with two cemented carbide inserts coated with TiN layer were used for end milling operation. Low carbon alloyed steel Cr-Mo forged at 1200 ºC was used as workpiece on the tests. Two kinds of workpiece conditions were considered, i.e. air cooled after hot forging and normalized at 950 ºC for 2 h. The results showed that finishing operation was able to significantly decrease the roughness by at least 46% without changing the hardness. On the other hand, roughing operation caused an increase in hardness statistically significant by about 6%. The machined surface presented deformed regions within feed marks, which directly affected the roughness. Surface finish behavior seems to correlate to the chip ratio given the decrease of 25% for roughing condition, which damaged the chip formation. The material removal rate for finishing operation 41% greater than roughing condition demonstrated to be favorable to the heat dissipation and minimized the effect on material hardness.
Applied Thermal Engineering, 2014
Proposed thermal models are simple and sensitive to the machining conditions. Models were validat... more Proposed thermal models are simple and sensitive to the machining conditions. Models were validated by other methods applied to solve direct-inverse problems. Methods may be used for any part materials, conditions and machining processes. 3D model approaches global one when uses mean workpiece temperature. Methods can also be extended to analyze cutting fluid performance.
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Papers by Alessandro Rodrigues