Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Chaotic oscillators have been implemented with a wide variety of discrete electronic devices and quite fewrealizations using integrated circuit technology. This article describes the synchronization of two chaotic oscillatorsalready fabricated with complementary metal-oxide-semiconductor (CMOS) integrated circuit technology of 0.5umand generating 3- and 5-scrolls. In order to attain the synchronization, we use a master-slave topology withunidirectional coupling. Within this context, a system parameter iterates until the correlation coefficient computedbetween the chaotic signals generated by the master and slave systems approximates to unity. For the followingparameter, its value depends on the standard deviations from the individual signals contrary to previous one. Bycombining those statistical relationships according to the number of system parameters, we can synchronizeintegrated chaotic oscillators. Theoretical model simulations of two chaotic oscillators generating 3- and 5-scrolls,and experimental results for two integrated 3-scroll chaotic oscillators validate this approach. Stability and erroranalysis are also included.

The growing importance of cooperation among organizations, as a result of globalization, current market opportunitiesand technological advances, encourages organizations to dynamically establish inter-organizational collaborations.These collaborations are carried out by executing collaborative business processes among the organizations. In thiswork we propose an agent-based software architecture for managing inter-organizational collaborations. Two types ofagents are provided: the Collaboration Administrator Agent and the Process Administrator Agent. The former allowsorganizations setting up collaborations. The latter allows organizations executing collaborative business processes. AColored Petri Net model specifying the role, which an organization fulfills in a collaborative process, is used to carryout the behavior of the Process Administrator Agent that represents the organization. Planning and execution of theactions of the Process Administrator Agents are driven by a Colored Petri Net machine embedded to them. Thus,Process Administrator Agents do not require to have defined at design-time the protocols they can support. Inaddition, we propose a model-driven development method for generating Colored Petri Net models from acollaborative process model defined as interaction protocol. Finally, an implementation of the agent-based softwarearchitecture and methods based on model-driven development are presented.

Background subtraction models based on mixture of Gaussians have been extensively used for detecting objects inmotion in a wide variety of computer vision applications. However, background subtraction modeling is still an openproblem particularly in video scenes with drastic illumination changes and dynamic backgrounds (complexbackgrounds). The purpose of the present work is focused on increasing the robustness of background subtractionmodels to complex environments. For this, we proposed the following enhancements: a) redefine the modeldistribution parameters involved in the detection of moving objects (distribution weight, mean and variance), b)improve pixel classification (background/foreground) and variable update mechanism by a new time-space dependentlearning-rate parameter, and c) replace the pixel-based modeling currently used in the literature by a new space-timeregion-based model that eliminates the noise effect caused by drastic changes in illumination. Our proposed schemecan be implemented on any state of the art background subtraction scheme based on mixture of Gaussians toimprove its resilient to complex backgrounds. Experimental results show excellent noise removal and object motiondetection properties under complex environments.

To effectively control and treat river water pollution, it is very critical to establish a water quality predictionsystem. Combined Principal Component Analysis (PCA), Genetic Algorithm (GA) and Back Propagation NeuralNetwork (BPNN), a hybrid intelligent algorithm is designed to predict river water quality. Firstly, PCA is used toreduce data dimensionality. 23 water quality index factors can be compressed into 15 aggregative indices. PCAimproved effectively the training speed of follow-up algorithms. Then, GA optimizes the parameters of BPNN.The average prediction rates of non-polluted and polluted water quality are 88.9% and 93.1% respectively, theglobal prediction rate is approximately 91%. The water quality prediction system based on the combination ofNeural Networks and Genetic Algorithms can accurately predict water quality and provide useful support for realtimeearly warning systems.

This paper presents an algorithm of simultaneous localization and mapping (SLAM) with a scanning laser range finderand radiofrequency identification technology (RFID) to include landmarks of an object or place within a generatedmap. For the testing phase was used of simulation software Anykode’s Marilou and was used to build a virtual mobilerobot with the features of the Pionner 3-AT, including a Hokuyo URG-04X scanning laser range finder and anInnovations RFID ID-12 reader. Validation of results was carried out with the cycle closure process to obtain theaverage error of the navigation path, resulting on an error of less than 50mm.

This paper presents three approaches dealing with the feedback control of nonlinear analytic systems. The first onetreats the optimal control resolution for a control-affine nonlinear system using the State Dependant Riccati Equation(SDRE) method. It aims to solve a nonlinear optimal control problem through a Riccati equation that depends on thestate. The second approach treats a procedure of constructing an analytic expression of a nonlinear state feedbacksolution of an optimal regulation problem with the help of Kronecker tensor notations. The third one deals with theglobal asymptotic stabilization of the nonlinear polynomial systems. The designed state feedback control law stabilizesquadratically the studied systems. Our main contribution in this paper is to carry out a stability analysis for this kind ofsystems and to develop new sufficient conditions of stability. A numerical-simulation-based comparison of the threemethods is finally performed.

Recently, several mathematical models have been developed to study and explain the way information isprocessed in the brain. The models published account for a myriad of perspectives from single neuron segments toneural networks, and lately, with the use of supercomputing facilities, to the study of whole environments of nucleiinteracting for massive stimuli and processing. Some of the most complex neural structures -and also moststudied- are basal ganglia nuclei in the brain; amongst which we can find the Neostriatum. Currently, just a fewpapers about high scale biological-based computational modeling of this region have been published. It has beendemonstrated that the Basal Ganglia region contains functions related to learning and decision making based onrules of the action-selection type, which are of particular interest for the machine autonomous-learning field. Thisknowledge could be clearly transferred between areas of research. The present work proposes a model ofinformation processing, by integrating knowledge generated from widely accepted experiments in both morphologyand biophysics, through integrating theories such as the compartmental electrical model, the Rall’s cable equation,and the Hodking-Huxley particle potential regulations, among others. Additionally, the leaky integrator framework isincorporated in an adapted function. This was accomplished through a computational environment prepared forhigh scale neural simulation which delivers data output equivalent to that from the original model, and that can notonly be analyzed as a Bayesian problem, but also successfully compared to the biological specimen.

This study investigated the coagulation potential of Moringa oleifera seed powder (SP) or its seed aqueous extract(SAE) on pH, electrical conductivity (EC) and heavy metals of sewage water after 1, 3 and 6 h contact time. Afteroptimizing, 2 g L-1 moringa SP, 40 mL L-1 SAE and 20 mg L-1 of alum alone or in combination were evaluated. MoringaSP was more effective than SAE and its combination to decrease EC and maintenance of pH of treated or untreatedsewage water. Moringa SAE was more effective than SP or their combination to decrease Lead (Pb) and Chromium(Cr) load from sewage water. Naturally occurring amino acids in moringa seeds might increased the metal binding anddecreased heavy metals load with maximum desorption on SP. Nonetheless, use of Moringa oleifera SP or its SAEcan be inexpensive and alternative coagulant of sewage water treatment.

Assuming that the thermo-creep response of the material is governed by Norton’s law, an analytical solution ispresented for the calculation of time-dependent creep stresses and displacements of homogeneous thick-walledcylindrical pressure vessels. For the stress analysis in a homogeneous pressure vessel, having material creepbehavior, the solutions of the stresses at a time equal to zero (i.e. the initial stress state) are needed. Thiscorresponds to the solution of materials with linear elastic behavior. Therefore, using equations of equilibrium, stressstrainand strain-displacement, a differential equation for displacement is obtained and then the stresses at a timeequal to zero are calculated. Using Norton’s law in the multi-axial form in conjunction with the above-mentionedequations in the rate form, the radial displacement rate is obtained and then the radial, circumferential and axial creepstress rates are calculated. When the stress rates are known, the stresses at any time are calculated iteratively. Theanalytical solution is obtained for the conditions of plane strain and plane stress. The thermal loading is as follows:inner surface is exposed to a uniform heat flux, and the outer surface is exposed to an airstream. The heat conductionequation for the one-dimensional problem in polar coordinates is used to obtain temperature distribution in thecylinder. The pressure, inner radius and outer radius are considered constant. Material properties are considered asconstant. Following this, profiles are plotted for the radial displacements, radial stress, circumferential stress and axialstress as a function of radial direction and time.

This paper is concerned with determining the optimal common production cycle policy for a multi-item economicproduction quantity (EPQ) model with scrap, rework and multiple deliveries. The classic EPQ model considers theoptimal replenishment quantity of single product under a perfect production assumption and a continuous inventoryissuing policy. However, in real life production planning, manufacturing firms often plan to have multiple productsmade in turn on a single machine in order to maximize the machine utilization. Also, dealing with random defectiveitems during the production run seems to be an inevitable task, and the multi-delivery policy is commonly adopted fordistributing finished items to customers. In this study, we assume a portion of nonconforming items is scrap and theother portion of them can be reworked and repaired in the same production cycle with additional cost. The objective isto determine an optimal common production cycle time that minimizes the long-run average cost per unit time for sucha specific multi-item EPQ model with scrap, rework and multi-delivery policy. Mathematical modeling and analysis isused and a closed-form optimal common cycle time for multi-item production planning is obtained. A numericalexample is provided to demonstrate the practical usage of research result.