Influence of reaction heat on time dependent processes in a chemically reacting binary mixture

In this paper we study time dependent problems, like the propagation of sound waves or the behavior of small local wave disturbances induced by spontaneous internal fluctuations, in a binary mixture undergoing a chemical reaction of type A+A= B+B. The study is developed at the hydrodynamic Euler level, in a chemical regime of fast reactive process in which the chemical reaction is close to its final equilibrium state. The hydrodynamic state of the mixture is described by the balance equations for the mass densities of both constituents A and B, together with the conservation laws for the momentum and total energy of the mixture. The progress of the chemical reaction is specified by an Arrhenius-type reaction rate which defines the net balance between production and consumption of each constituent. Assuming that the considered time dependent problems induce weak macroscopic deviations, the hydrodynamic equations are linearized through a normal mode expansion of the state variables around the equilibrium state. From the dispersion relation of the normal modes, we determine the free and forced phase velocities as well as the attenuation coefficients of the waves. We show that the dispersion and absorption of these waves depend explicitly on the heat of the chemical reaction, the concentrations of the constituents and the activation energy through the exponential factor of Arrhenius law.Fundação para a Ciência e a Tecnologia, Brazilian Research Council (CNPq

Manual de perdas pós-colheita em frutos e hortaliças.

Produção e perdas de frutos e hortaliças no Brasil. Perdas: definição, tipos e causas. Alguns aspectos envolvidos no controle das perdas: pré-colheita; colheita; pós-colheita; embalagem; transporte; armazenamento. Aspectos de mercado.bitstream/item/33932/1/1997-DOC-0027.pd

Spectral distribution of scattered light from a chemical relaxation system

The aim of this work is to describe the light scattering spectra of a quaternary reacting gas mixture from the macroscopic field equations derived from the kinetic BGK-type model proposed by the authors in a previous paper. The study is developed in a hydrodynamic regime for which the system of the field equations of constituent number densities, momentum and temperature of the mixture is closed by the constitutive equations for rate of reaction, diffusion velocities, pressure tensor and heat flux vector. The spontaneous Rayleigh-Brillouin scattering is calculated from the constituent density perturbations of the linearized field equations, and its line shape is drawn for two different mixtures of the Hydrogen-Chlorine system showing the induced chemical reaction effect.Brazilian Research Council (CNPq)Universidade do Minho. Centro de Matemática(CMat)Fundação para a Ciência e a Tecnologia (FCT) - FCT-PTDC/MAT/68615/2006Italian National Project GNFM 2009/1

A kinetic model for chemical reactions without barriers : transport coefficients and eigenmodes

The kinetic model of the Boltzmann equation proposed in the work of Kremer and Soares 2009 for a binary mixture undergoing chemical reactions of symmetric type which occur without activation energy is revisited here, with the aim of investigating in detail the transport properties of the reactive mixture and the influence of the reaction process on the transport coefficients. Accordingly, the non-equilibrium solution of the Boltzmann equation is determined through an expansion in Sonine polynomials up to the first order, using the Chapman-Enskog method, in a chemical regime for which the reaction process is close to its final equilibrium state. The non-equilibrium deviations are explicitly calculated for what concerns the thermal-diffusion ratio and coefficients of shear viscosity, diffusion and thermal conductivity. The theoretical and formal analysis developed in the present paper is complemented with some numerical simulations performed for different concentrations of reactants and products of the reaction as well as for both exothermic and endothermic chemical processes. The results reveal that chemical reactions without energy barrier can induce an appreciable influence on the transport properties of the mixture. Oppositely to the case of reactions with activation energy, the coefficients of shear viscosity and thermal conductivity become larger than those of an inert mixture when the reactions are exothermic. An application of the non-barrier model and its detailed transport picture is included in this paper, in order to investigate the dynamics of the local perturbations on the constituent number densities, and velocity and temperature of the whole mixture, induced by spontaneous internal fluctuations. It is shown that for the longitudinal disturbances there exist two hydrodynamic sound modes, one purely diffusive hydrodynamic mode and one kinetic mode.This paper is partially supported by the Brazilian Research Council (CNPq), by Minho University Mathematics Centre (CMAT-FCT) and by Project FCT-PTDC/MAT/68615/2006

Aumento da vida de prateleira de goiaba utilizando tratamento com radiação ionizante.

bitstream/item/75833/1/ct38-2000.pd

\u3cem\u3eBrachiaria Spp.\u3c/em\u3e (Syn. \u3cem\u3eUrochloa Spp.\u3c/em\u3e) CV. Mulato Ii (Convert HD364) Mass Production Under Continuous Grazing in the Water/Dry Transition Period

In the transition period between the rainy and dry seasons there is decreased water, temperature and luminosity, reducing forage production and quality. Because of this variability in forage mass production, it is essential to quantify forage mass for use in planning and decision making about pastures management. The objective was to evaluate Brachiaria spp. (Syn. Urochloa spp.) cv. Mulato II (Convert HD364) growth, biomass production managed under continuous grazing with steers fed with protein supplement feed in-trough and on-ground during the seasonal transition period. The experiment was carried out in the Beef Cattle Sector of Jatai Federal University (UFJ), Brazil, from March to June 2020, in a completely randomized design, using 18 male Nellore steers at 24 months of age, with two animals per paddock. Variance analysis was performed by SAS software using the GLM procedure and time repeated measures with significance set to P \u3c 0.05. There was no significant difference between way of supplementation. In the rainy/drought transition period, Convert-grass produced 7,622 kg DM/ha and 1,995 kg DM/ha of leaf mass. The pelleted protein supplement can be used both in-trough or with onground because the method of feeding did not change the forage offered but the canopy was undergrazed which could biased the responses to the supply method evaluated

Análise morfológica de farinhas de arroz cruz e submetidas à torração em micro-ondas.

Objetivou-se avaliar o efeito da umidificação, em diferentes proporções, seguida de torra em micro-ondas, em diferentes tempos, na morfologia de farinhas de arroz oriundas de grãos quebrados da cv. IRGA 417. Foram realizadas microscopia eletrônica de varredura em farinhas de arroz pouco torrada (10 min de torra e umidade ajustada para 14,3 g (100g)- 1), muito torrada (22 min e 18,7 g (100g)-1) e farinha com torração intermediária (15 min e 18,7 g (100g)-1) e também na amostra crua de farinhas de arroz da cv. IRGA 417. Foram avaliadas os resultados em 2000x. As micrografias mostraram pequena diferença estrutural entre as farinhas torradas e a farinha crua. Não havendo diferenças na morfologia das farinhas de arroz da cv. IRGA 417 torradas em diferentes tempos em micro-ondas.Edição dos anais do 20º Congresso Brasileiro de Nutrição e III Ibero-Americano de Nutrição, 2012

Predicting Transportation Modes of GPS Trajectories using Feature Engineering and Noise Removal

Understanding transportation mode from GPS (Global Positioning System) traces is an essential topic in the data mobility domain. In this paper, a framework is proposed to predict transportation modes. This framework follows a sequence of five steps: (i) data preparation, where GPS points are grouped in trajectory samples; (ii) point features generation; (iii) trajectory features extraction; (iv) noise removal; (v) normalization. We show that the extraction of the new point features: bearing rate, the rate of rate of change of the bearing rate and the global and local trajectory features, like medians and percentiles enables many classifiers to achieve high accuracy (96.5%) and f1 (96.3%) scores. We also show that the noise removal task affects the performance of all the models tested. Finally, the empirical tests where we compare this work against state-of-art transportation mode prediction strategies show that our framework is competitive and outperforms most of them.Comment: 6 page

Levantamento Aéreo Expedito (LAE).

bitstream/CNPF-2009-09/42643/1/Doc157.pdf1 CD-ROM