Danos de lagartas de Elasmopalpus lignosellus no feijoeiro.

Elasmopalpus lignosellus (Zeller), conhecida como lagarta elasmo, é considerada uma das principais pragas de diversas culturas, causando danos elevados no feijoeiro em períodos de estiagem. Foi avaliado nesse trabalho o dano da lagarta de diferentes idades no feijoeiro no estágio de folhas primárias: 1) lagartas de um dia; 2) lagartas de três dias; 3) lagartas de cinco dias; 4) lagartas de sete dias; 5) lagartas de nove dias; 6) testemunha (sem inseto).Resumo

Danos de lagartas de Elasmopalpus lignosellus no feijoeiro.

Foi avaliado nesse trabalho o dano da lagarta de diferentes idades no feijoeiro no estágio de folhas primárias: 1) lagartas de um dia; 2) lagartas de três dias; 3) lagartas de cinco dias; 4) lagartas de sete dias; 5) lagartas de nove dias; 6) testemunha (sem inseto). Dez sementes da cv. Pérola foram semeadas em Latossolo vermelho escuro contido em vaso de plástico preto (12,5 cm altura, 16 cm diâmetro) em 24/08/2010

Avaliação do escurecimento e endurecimento de genótipos de feijão carioca durante armazenamento.

o objetivo deste trabalho foi avaliar se existe variação entre tempo de cocção e coloração de diferentes genótipos durante o armazenamento, a fim de se identificar cultivares mais estáveis em relação a estas características.CONAFE

Predicting Thermoelectric Power Plants Diesel/Heavy Fuel Oil Engine Fuel Consumption Using Univariate Forecasting and XGBoost Machine Learning Models

Monitoring and controlling thermoelectric power plants (TPPs) operational parameters have become essential to ensure system reliability, especially in emergencies. Due to system complexity, operating parameters control is often performed based on technical know-how and simplified analytical models that can result in limited observations. An alternative to this task is using time series forecasting methods that seek to generalize system characteristics based on past information. However, the analysis of these techniques on large diesel/HFO engines used in Brazilian power plants under the dispatch regime has not yet been well-explored. Therefore, given the complex characteristics of engine fuel consumption during power generation, this work aimed to investigate patterns generalization abilities when linear and nonlinear univariate forecasting models are used on a representative database related to an engine-driven generator used in a TPP located in Pernambuco, Brazil. Fuel consumption predictions based on artificial neural networks were directly compared to XGBoost regressor adaptation to perform this task as an alternative with lower computational cost. AR and ARIMA linear models were applied as a benchmark, and the PSO optimizer was used as an alternative during model adjustment. In summary, it was possible to observe that AR and ARIMA-PSO had similar performances in operations and lower error distributions during full-load power output with normal error frequency distribution of −0.03 ± 3.55 and 0.03 ± 3.78 kg/h, respectively. Despite their similarities, ARIMA-PSO achieved better adherence in capturing load adjustment periods. On the other hand, the nonlinear approaches NAR and XGBoost showed significantly better performance, achieving mean absolute error reductions of 42.37% and 30.30%, respectively, when compared with the best linear model. XGBoost modeling was 8.7 times computationally faster than NAR during training. The nonlinear models were better at capturing disturbances related to fuel consumption ramp, shut-down, and sudden fluctuations steps, despite being inferior in forecasting at full-load, especially XGBoost due to its high sensitivity with slight fuel consumption variations

Possible chiral phase transition in two-dimensional solid 3^3He

We study a spin system with two- and four-spin exchange interactions on the triangular lattice, which is a possible model for the nuclear magnetism of solid $^3$He layers. It is found that a novel spin structure with scalar chiral order appears if the four-spin interaction is dominant. Ground-state properties are studied using the spin-wave approximation. A phase transition concerning the scalar chirality occurs at a finite temperature, even though the dimensionality of the system is two and the interaction has isotropic spin symmetry. Critical properties of this transition are studied with Monte Carlo simulations in the classical limit.Comment: 4 pages, Revtex, 4 figures, to appear in Phys.Rev.Let

Magnetization plateau in a two-dimensional multiple-spin exchange model

We study a multiple-spin exchange model on a triangular lattice, which is a possible model for low-density solid 3He films. Due to strong competitions between ferromagnetic three-spin exchange and antiferromagnetic four-spin one, the ground states are highly degenerate in the classical limit. At least 2^{L/2}-fold degeneracy exists on the L*L triangular lattice except for the SO(3) symmetry. In the magnetization process, we found a plateau at m/m_{sat}=1/2, in which the ground state is "uuud state" (a collinear state with four sublattices). The 1/2-plateau appears due to the strong four-spin exchange interaction. This plateau survives against both quantum and thermal fluctuations. Under a magnetic field which realizes the "uuud" ordered state, a phase transition occurs at a finite temperature. We predict that low-density solid 3He thin films may show the 1/2-plateau in the magnetization process. Experimental observation of the plateau will verify strength of the four-spin exchange. It is also discussed that this magnetization plateau can be understood as an insulating-conducting transition in a particle picture.Comment: 10 pages, RevTeX, 12 figures, added a reference and corrected typos, to be published in Phys.Rev.B (01 APR 99

Efeito de câmara simuladora de radiação solar sobre cor e tempo de cocção de grãos de feijão carioca.

O objetivo do trabalho foi analisar o efeito da câmara simuladora de radiação solar sobre as características de cor e tempo de cocção de feijão carioca.CONAFE