Emergence of synchronicity in a self-organizing spiking neuron network: an approach via genetic algorithms

Based on the Theory of Neuronal Group Selection (TNGS), we have investigated the emergence of synchronicity in a network composed of spiking neurons via genetic algorithm. The TNGS establishes that a neuronal group is the most basic unit in the cortical area of the brain and, as a rule, it is not formed by a single neuron, but by a cluster of tightly coupled neural cells which fire and oscillate in synchrony at a predefined frequency. Thus, this paper describes a method of tuning the parameters of the Izhikevich spiking neuron model through genetic algorithm in order to enable the self-organization of the neural network. Computational experiments were performed considering a network composed of neurons of the same type and another composed of neurons of different types.     

The Use of Duo-Functional PVC Film for Conservation of Minimally Processed Apples

Several conservation strategies regarding minimally processed vegetables (MPV) are applied keep organoleptic features and quality, in particular the use of active packaging to slow down enzymatic browning reactions and microbial growth. Based on such context, polyvinyl chloride (PVC) films with antimicrobial and antibrowning properties—due to the addition of a mix of additives (MA) that comprise pure (KM) and encapsulated (EKM) potassium metabisulfite—are the core of the current study to find out their influence on the quality parameters applied to minimally processed apples. The sol–gel method was used in the encapsulation process and the PVC films were prepared by applying 0.1 (w/w; F01), 1.0 (w/w; F1), and 2.0 (w/w; F2) of MA (KM and EKM), as well as the use of control film, for industrial extrusion processing. The EKM was chemically and morphologically characterized and the mechanical properties of the films were set. Minimally processed apples were prepared and packed in films for 20 days. The prepared packages were stored at different temperatures and evaluated for color variations as well as for chemical and microbiological quality. The encapsulation process increased the additive's thermal resistance. It also preserved the main characteristics of the additives that were incorporated into the process. It did not interfere in the machinability conditions of the films. The outcomes showed satisfactory effects regarding the maintenance of color and microbiological qualities. The F2 film could show toxicological safety for the minimally processed apples for 10 days at 8 °C. Therefore, duofunctional films are a good alternative for minimally processed apples storage.     

Failure Analysis and Mechanical Performance Evaluation of a Cast Aluminum Hybrid-Iron Golf Club Hosel

This article details the failure analysis of a commercial golf club hybrid-iron that fractured through the hosel during normal use. The golf club hosel was manufactured from a cast aluminum alloy, and the optical analysis revealed casting pores up to 20% through the hosel thickness. Mechanical properties of the aluminum alloy were determined for material characterization and used to construct a finite element model to analyze the performance of the material under failure conditions. In addition, a full structural scale experiment was conducted to determine the failure strength.     

Action of andiroba oil (Carapa guianensis) on Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi‐engorged females: Morphophysiological evaluation of reproductive system

Because of the increasing medical‐veterinary importance of ticks, the development of alternative control methods, less aggressive to the host and the environment has become the target of several researches. In this sense, the present study analyzed the action of different concentrations (5, 10, and 20%) of andiroba seed oil (Carapa guianensis) on the reproductive system of Rhipicephalus sanguineus females, through histochemical techniques and the quantification of the reproductive efficiency index. The results showed that andiroba oil is a potent natural agent, able to cause several changes in the oocytes of this species, impairing the reproductive success, once this natural product induces great physiological changes in the oocytes in all development stages, such as drastic reduction in proteins, polysaccharides, and lipids in these cells, and these components are essential for the viability of the embryo. In addition, it was observed that this product stimulate the oviposition, mainly at the concentration of 20%. This higher production of eggs represents a defense mechanism developed by the organism in order to ensure the reproductive success of the species, even in the presence of the toxic agent. However, the results obtained suggested that the laid eggs would not be viable, due to the great changes undergone by the oocytes. Thus, the present study showed that the use of this vegetal product would be an alternative way to control the ticks, bringing benefits similar to the ones obtained through the use of synthetic acaricides; however, with less damage to nontarget organisms and the environment as well. Microsc. Res. Tech., 2012. © 2012 Wiley Periodicals, Inc.     

QACO_Alpha applied to the nuclear reactor core fuel reload optimization

The nuclear reload optimization is an important issue to nuclear engineering. It consists on maximizing the length of the operation cycle of the power plant. The aim is to find a configuration of the fresh fuel assemblies and remnants in order to keep the power plant running at full power by the largest time as possible.Quantum-inspired evolutionary algorithms are optimization tools based in artificial intelligence developed to simulate the quantum processing in classical computers. In this work is introduced one of these tools, which adds quantum concepts to the biological metaphor of collective learning of the real ants, named QACO_Alpha. It uses mechanisms developed in order to avoid premature convergence problems like a pheromone evaporation step besides a new updating method.To show its effectiveness, QACO_Alpha was applied to the optimization of 7th cycle of Angra 1. Experimental results were confronted to that obtained with other optimization methods, qualifying QACO_Alpha as a valid optimization tool for this kind of problem.     

Desorption isotherms and thermodynamic properties of sweet corn cultivars (Zea mays L.)

The desorption isotherms and thermodynamic properties of two cultivars of sweet corn were obtained during the drying process of these products. The isotherms were determined by a dynamic method for various temperature and humidity conditions. Equilibrium moisture content (X_eq) data were correlated by the Guggenheim–Anderson–de Boer model and an artificial neural network (ANN) model. These models were fitted to the experimental data. The X_eq for corn grain increased with an increase in the relative humidity at fixed temperature and decreased with an increase in temperature at a constant relative humidity. The experimental data were analysed by a thermodynamic approach to obtain the isosteric heat of desorption (ΔH), differential entropy (ΔS), activation energy (E_a) and Gibbs free energy (ΔG). The ΔH and ΔS increased with a decrease in moisture content, while ΔG decreased exponentially with an increase in X_eq. The Arrhenius equation was used to obtain E_a values, with Supersweet corn having higher E_a.     

In situ and ex situ spectroscopic study of poly(3-hexylthiophene) electrochemically synthesized

In this work, poly(3-hexylthiophene) (P3HT) film was synthesized electrochemically in non-aqueous media through the oxidation of the 3-hexylthiophene monomer using a standard three-electrode cell in acetonitrile with 0.100 mol L^?1 LiClO₄. The polymeric thick film was deposited on platinum plates for best quality control of the process. Cyclic voltammetry of this material showed two bands of oxidation and two bands of reduction attributed to radical cation and dication segments in the polymer chain. These were characterized by reflectance and Raman spectra, of the reduced (chemically de-doped) and oxidized (electrochemically doped) films. The generated film was subjected to anodic potentials of 1.00 and 1.45 V and characterized by an in situ Raman technique, which indicated the stabilization of the radical cation segments. In addition Raman ex situ spectra of as-prepared film was obtained. The increase in the irradiation time of the sample was enough to alter the nature of the constituent species of the oxidized film, preferably favoring the aromatic chains, together with the dication segments. Photoluminescence spectra showed a larger contribution of dication than radical cation segments for the chemically de-doped sample and under this condition showed good stability, even with variation in laser power. SEM images of P3HT film with indication of the thickness and spherical shape of the sample studied were obtained. Aided by these data it was possible to verify the Stokes shift and ionization potential (I _p), electron affinity (E.A.) and energy gap (E _g) parameters.     

Using finite element modeling to examine the temperature distribution in quasi-constrained high-pressure torsion

Processing by quasi-constrained high-pressure torsion (HPT) is important for achieving substantial grain refinement in bulk solids, but very little information is available at present on the rise in temperature that occurs in the HPT specimens during the processing operation. This problem was addressed by using finite element modeling with an analytical component to evaluate the thermal characteristics in quasi-constrained HPT. The analysis incorporates the effects of various parameters, including the material strength, the rotation rate, the applied pressure and the volume of the anvils. The calculations show that the temperature rise varies directly with the material strength and the rotation rate, but depends only slightly on the applied pressure. Using this analysis, a normalized master curve is constructed that may be used to predict the rise in temperature during HPT processing. It is demonstrated that the predictions from this curve are in good agreement with experimental data for three different materials.     

Influence of the relative amounts of crystalline and amorphous phases on the mechanical properties of polyamide-6 nanocomposites

The relative amounts of amorphous and crystalline γ- and α-phases in polyamide-6 nanocomposites, estimated from the deconvolution of X-ray diffraction peaks using Gaussian functions, correlates with their mechanical, thermomechanical, and barrier properties. The incorporation of organoclay platelets (Cloisite 15A and 30B) induced the crystallization of the polymer in the γ form at expense of the amorphous phase, such that 1–2 wt % of Cloisite is enough to enhance the mechanical and the thermomechanical properties. However, higher nanofiller loads were necessary to achieve good barrier effects, because this property is mainly dependent on the tortuous path permeation mechanism of the gas molecules through the nanocomposite films. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Adaptation for tandem cold mill models

The ideal conditions for the operation of tandem cold mills are connected to a set of references generated by models and used by dynamic regulators. Aiming at the optimization of the friction and yield stress coefficients an adaptation algorithm is proposed in this paper. Experimental results obtained from an industrial cold rolling mill are presented.