An optimization model for combined selecting,planting and harvesting sugarcane varieties

The problem of selecting sugarcane varieties has been widely discussed due to its computational complexity and its great impact for the sugar and ethanol industry. This paper proposes a new integrated mathematical programming model to deal with the selection of sugarcane varieties to be planted and the determination of the optimal period for planting and harvesting in order to increase production in the sugarcane industry. The proposed model optimizes the production of sugarcane and improves the quality of biomass whilst satisfying the main constraints imposed by sugarcane companies. The problem is modelled as an integer linear program and solved using an exact method to generate optimal solutions for small and medium problems. For large problems, metaheuristic approaches based on Genetic Algorithm and Variable Neighbourhood Search are proposed. According to the results, the proposed methodology provides sugarcane company managers with decision support in selecting the most suitable varieties and in determining the best period to plant and harvest their sugarcane.

     

Remediation of copper ions from aqueous solution using hybrid magadiite: kinetics,isotherm and mechanism of removal

Research on Chemical Intermediates - This paper deals with the potential use of hybrid magadiite composite as an alternative adsorbent for the removal of copper ions. Na-magadiite was synthesized...     

Chaotic behavior analysis based on corner bifurcations

In this paper, a mathematical analysis in order to generate a chaotic behavior for bounded piecewise smooth systems of dimension three submitted to one of its specific bifurcations, namely the corner one, is proposed. This study is based on period doubling method.     

Local solutions to a model of piezoelectric materials

A local existence theorem is proved for a non‐linear coupled system modelling the electromechanical motion of a one‐dimensional piezoelectric body with domain switching. The system is composed by a heat equation describing the behaviour of the number of electric dipoles and by a wave equation governing the dynamic of the electric displacement. The main coupling in the system appears in the time‐dependent velocity of the waves depending on the number of electric dipoles. The proof of the result relies on a time decay estimate satisfied by the number of electric dipoles and an uniform estimate of the solution of the regularized wave equation. Copyright © 2004 John Wiley & Sons, Ltd.     

Luminescence-Driven Electronic Structure Determination in a Textbook Dimeric DyIII-Based Single-Molecule Magnet

A textbook dysprosium dinuclear complex based on acetylacetone ligands, [Dy₂(acac)₄(μ₂-acac)₂(H₂O)₂], has been synthesized and fully characterized. This simple dimeric lanthanide complex shows well-resolved solid-state luminescence and behaves as a single-molecule magnet under zero DC field. A seminal crystal-field approach is used to marry both magnetism and luminescence in the frame of an energetic picture.     

Thermal decomposition of calcium oxalate: beyond appearances

The goal of this study is twofold: to take a fresh look at the decomposition of calcium oxalate and to warn users of thermogravimetric analysis against the hasty interpretation of results obtained. Since the pioneer work of Duval 70 years ago, the scientific community has agreed unanimously as to the decomposition of anhydrous calcium oxalate (CaC₂O₄) into calcium carbonate (CaCO₃) and CO gas, and that of the calcium carbonate into calcium oxide (CaO), and CO₂ gas. We will demonstrate how these reactions, simple in appearance, in fact result from a succession of reactive phenomena involving numerous constituents both solid (CaCO₃, free carbon) and gaseous (CO₂ and CO) produced by intermediary reactions. The mass losses evaluated in the two distinct domains correspond closely to the molar masses of CO and CO₂, respectively. The simple mathematical calculation of that mass loss has simply concealed the existence of other reactions, and, most particularly the Boudouard reaction and that of solid phases between CaCO₃ and C. It just goes to show that appearances can be deceiving.

     

Synthesis and Diels-Alder reactivity of ortho-carbazolequinones

Oxidation of 2- and 3-hydroxycarbazoles with Frémy's salt gave the corresponding ortho-carbazolequinones. These molecules react as carbodienophiles in Diels-Alder reaction with 1-acetoxy-1,3-butadiene and 1,3-cyclopentadiene to provide the novel benzocarbazolequinone structures 15, 16, 18 and 19.     

A general route to synthesize supported isolated oxide and mixed-oxide nanoclusters at sizes below 5 nm

A simple and efficient route to prepare supported nanocrystalline oxides is presented. The synthesis procedure, i.e. in situ autocombustion of a glycine complex, allows the production of nanocrystals in a porous matrix presenting larger pore size. An example of successful formation of 2-5 nm nanocrystals is given for a single oxide (Fe(2)O(3)), a mixed-oxide structure (LaCoO(3) perovskite-type) and a nickel-doped oxide.     

Interval propagation and search on directed acyclic graphs for numerical constraint solving

The fundamentals of interval analysis on directed acyclic graphs (DAGs) for global optimization and constraint propagation have recently been proposed in Schichl and Neumaier (J. Global Optim. 33, 541–562, 2005). For representing numerical problems, the authors use DAGs whose nodes are subexpressions and whose directed edges are computational flows. Compared to tree-based representations [Benhamou et al. Proceedings of the International Conference on Logic Programming (ICLP’99), pp. 230–244. Las Cruces, USA (1999)], DAGs offer the essential advantage of more accurately handling the influence of subexpressions shared by several constraints on the overall system during propagation. In this paper we show how interval constraint propagation and search on DAGs can be made practical and efficient by: (1) flexibly choosing the nodes on which propagations must be performed, and (2) working with partial subgraphs of the initial DAG rather than with the entire graph. We propose a new interval constraint propagation technique which exploits the influence of subexpressions on all the constraints together rather than on individual constraints. We then show how the new propagation technique can be integrated into branch-and-prune search to solve numerical constraint satisfaction problems. This algorithm is able to outperform its obvious contenders, as shown by the experiments.     

Biotreatment on Cellulose Fluff Pulp: Quaternary Ammonium Salts Finish and Grafting with β-cyclodextrin

For its potential performances to be expanded, cellulose needs to be processed in different ways. Therefore, an object of the present work was to provide a chemical modification of cellulose through: a specific finish with two quaternary ammonium salts (namely Aliquat 336 and Aliquat 1529, respectively). Chemical grafting of β-cyclodextrin derivative (β-CD) onto fibers followed by the inclusion of benzoic acid in the grafted CD cavities as a probe chemical. Physicochemical properties and performances of the untreated and treated fibers have been determined with infrared spectra, microscopy, swelling measurements, antimicrobial finishing tests, and dye adsorption. Our results show that cellulose fibers can be efficiently modified with no significant changes in its structural and surface properties; the treated fibers show an attractive behavior in swelling, dye adsorption and antibacterial activity.