Fernando da Silva Barbosa

Níveis de salinidade e manejo da fertirrigação sobre características da berinjela cultivada em ambiente protegido

Objetivou-se estudar os efeitos de diferentes niveis de salinidade do solo sobre as variaveis fenologicas e de producao da berinjela, cultivada em vasos e em ambiente protegido. O estudo foi conduzido na area experimental do Departamento de Engenharia de Biossistemas da ESALQ/USP, Piracicaba, SP. Os tratamentos foram compostos da combinacao de dois fatores: 6 niveis de salinidade inicial do solo (S1 = 1,3; S2 = 2,4; S3 = 3,6; S4 = 4,5; S5 = 5,6 e S6 = 6,4 dS m-1) e dois manejos de fertirrigacao: com controle da condutividade eletrica da solucao do solo (M1), e o tradicional (M2), obedecendo a curva de absorcao de nutrientes da cultura. O delineamento estatistico adotado foi o de blocos casualizados completos, com quatro repeticoes, arranjados no esquema fatorial 6 x 2. Os resultados revelaram que os niveis de salinidade do solo afetaram diretamente as variaveis, producao de materia seca, producao de frutos e indice de area foliar das plantas. Verificou-se que a reducao media na producao da cultura da berinjela, em estufa, foi da ordem de 8,65% para o incremento de 1 dS m-1 na salinidade do solo, acima da salinidade limiar, que foi de 1,71 dS m-1.

Drought resistance of sugar-cane crop for different levels of water availability in the soil

Soil water availability is the main cause of reduced productivity, and the early development period most sensitive to water deficit. This study aimed to evaluate the drought resistance of the varieties of sugar-cane RB867515 and SP81-3250 during the early development using different levels of water deficit on four soil depths. The experiment was conducted at the Department of Biosystems at Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP) in a greenhouse in soil classified as Oxisol, sandy loam texture (Series Sertaozinho). Once exhausted the level of available water in the soil, the dry strength of the studied strains are relatively low. Water balance with values less than -13 mm cause a significant decrease in the final population of plants, regardless of the variety, and values below -35 mm, leads to the death of all plants.

Discrete LQG/LTR control augmented by integrators applied to a 2-DOF helicopter

Linear Quadratic Gaussian (LQR) controller and Kalman Filter (KF) both are robust when acting separately, but this property is lost if using them together. Therefore, a Loop Transfer Recovery (LTR) is made aiming to recover this robustness. This same statement is valid for discrete time LQG/LTR, and this work presents its application in a 2-DOF helicopter. The complete mathematical modeling is developed using Lagranges method and the system is linearized around the operating point. Digital LQG/LTR control project is made along with integrator insertion to the plant inputs. This helicopter is an interesting plant, allowing the study of many subjects, such as Kalman Filters, sensor fusion, modeling techniques and classical control. Simulation and practical results are presented, showing the controller effectiveness.

Discrete time LQG/LTR applied to a practical quadruple tank system

Discrete time robust linear quadratic Gaussian controller with loop transfer recovery (LQG/LTR) considering the augmented system with the addition of backward Euler integrator at controller output is applied to a practical quadruple tank system. The plant developed in this work is a benchmark of a multivariable two-input-two-output (TITO) system with coupled channels, frequently used in academic works, mainly due to its versatility for generating minimum phase or non-minimum phase systems and to the coupled channels characteristic. For the LQG/LTR controller, the singular values of the open loop transfer function are matched in the frequency range from zero up to the Nyquist rate using the same approach considered for continuous time system design. Simulation and practical experiments are performed in order to validate the controller design considering set-point tracking and disturbance rejection. It is possible to observe that the resulting controller performs very well tracking step and sinusoidal inputs and rejecting sinusoidal disturbances. Practical and simulated results are very similar to each other.

Water Productivity into Biomass and Energy for 24 Brazilian Sugarcane Varieties Under Drip Irrigation

Abstract: The purpose of this study was to evaluate the water productivity (PA) into biomass, sugar and energy for 24 brazilian sugarcane varieties under drip irrigation, subjected to full and deficit irrigation treatments during growing stage. Two experiments were established under greenhouse conditions at the Biosystems Engineering Department, ESALQ/USP, Piracicaba, SP. Experiment 1: ten varieties on a clay soil (RB835054, RB855453, RB855536, RB925211, RB867515, SP89-1115, SP81-3250, CTC14, CTC8 e CTC6) and Experiment 2: fourteen varieties on a sandy-loam soil (RB925345, RB855156, RB966928, RB72454, RB92579, IACSP95-5000, Caiana, SP83-2847, SP90-3414, SP79-1011, CTC17, CTC15, CTC9 e CTC2). In both experiments it was adopted two irrigation treatments: T100 - full irrigation with 100% crop evapotranspiration replacement, maintaining soil moisture near field capacity, and T70 - irrigation with 70% of water depth applied to T100 treatment. Irrigation treatments were initiated at 101 days of crop cycle, corresponding to the end of tillering and the beginning of intense stalk growth phase (first ratoon). It was observed variation in the water productivity into fresh stalk biomass (PABFC) from 16.22 to 29.21 kg m-3, according of the varieties and irrigation treatments applied. The highest values were observed for varieties CTC6, CTC14, RB867515, SP81-3250 and RB92579, under full irrigation treatment (T100), and CTC6, CTC14 and SP90-3414, under deficit irrigation treatment (T70). Water productivity into sugar (PABATR) ranged from 1.95 to 3.84 kg m-3, highest values were observed for varieties CTC6 and RB92579 (T100), as well as RB835054 e RB966928 (T70). Water productivity into total energy (PAETOT) varied from 101.17 to 174.65 MJ m-3, with highest values for varieties:SP81-3250, CTC6, CTC17 and RB92579 (T100 treatment), as well as SP90-3414, SP81-3250 and CTC6 (T70 treatment).