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

It has been shown that, at least in simulated scenarios of variability decomposition in size and frequency, the waythese components are measured largely determines the shape of their relationships. This study aims to build on thisspecific finding and tests how these measures of variability components behave on real data. Moreover, gettingadvantage of the type of available data, several models are setup to assess amplification on such variabilitycomponents, and to evaluate the impact of the product type on both: amplification and component variabilitybehaviors. We do this by performing model assessment with the traditional un-weighted C.V. measure, and thenreplicating the same evaluation with the recently proposed ADV measure.

This paper describes the integration and implementation of a satellite flight simulator based on an air bearingsystem, which was designed and instrumented in our laboratory to evaluate and to perform research in the field ofAttitude Determination and Control Systems for satellites, using the hardware-in-the-loop technique. The satelliteflight simulator considers two main blocks: an instrumented mobile platform and an external computer executingcostume-made Matlab® software. The first block is an air bearing system containing an FPGA based on-boardcomputer with capabilities to integrate digital architectures for data acquisition from inertial navigation sensors,control of actuators and communications data handling. The second block is an external personal computer, whichruns in parallel Matlab® based algorithms for attitude determination and control. Both blocks are linked by meansof radio modems. The paper also presents the analysis of the satellite flight simulator dynamics in order to obtainits movement equation which allows a better understanding of the satellite flight simulator behavior. In addition, thepaper shows experimental results about the automated tracking of the satellite flight simulator based a virtualreality model developed in Matlab®. It also depicts two different versions of FPGA based on-board computersdeveloped in-house to integrate embedded and polymorphic digital architectures for spacecrafts applications.Finally, the paper shows successful experimental results for an attitude control test using the satellite flightsimulator based on a linear control law.

The zones design occurs when small areas or basic geographic units (BGU) must be grouped into acceptable zonesunder the requirements imposed by the case study. These requirements can be the generation of intra-connectedand/or compact zones or with the same amount of habitants, clients, communication means, public services, etc. Inthis second point to design a territory, the selection and adaptation of a clustering method capable of generatingcompact groups while keeping balance in the number of objects that form each group is required.The classic partitioning stands out (also known as classification by partition among the clustering or classificationmethods [1]). Its properties are very useful to create compact groups.An interesting property of the classification by partitions resides in its capability to group different kinds of data.When working with geographical data, such as the BGU, the partitioning around medoids algorithms have givensatisfactory results when the instances are small and only the objective of distances minimization is optimized. Inthe presence of additional restrictions, the K-medoids algorithms, present weaknesses in regard to the optimalityand feasibility of the solutions.In this work we expose 2 variants of partitioning around medoids for geographical data with balance restrictions overthe number of objects within each group keeping the optimality and feasibility of the solution. The first algorithmconsiders the ideas of k-meoids and extends it with a recursive constructive function to find balanced solutions. Thesecond algorithm searches for solutions taking into account a balance between compactness and the cardinality of thegroups (multiobjective). Different tests are presented for different numbers of groups and they are compared withsome results obtained with Lagrange Relaxation. This kind of grouping is needed to solve aggregation for TerritorialDesign problems.

The main objective of the construction of a robot station presented in this article is to allow the students to design andproduce a feasible-to-build mechatronic device using robust, low-cost components. It is a tool for students to gainexperience integrating different mechatronic fields of knowledge, as well as practicing the procedures needed tosuccessfully accomplish their own design. The project starts by describing the target requirements to be achieved bythe prototype robot, these requirements will serve as the guideline for the design and further manufacture and testingof the system. The sub-assemblies of the mechanism are analyzed, main technical areas and their processes arediscussed individually emphasizing the methods and materials used, then results are presented along with somepractical recommendations to extend the scope of the project and improve the performance of the prototype robot. Ithas been especially important to maintain the didactical approach and design the platform with affordable componentsthat can be easily obtained; this is also true for the tools and software used. The article is also intended to introducethe student to industrial design methodology, allowing for different manufacturing processes and robot architectures tobe incorporated for the specific scope of the project and the available tools and facilities.

The generalized Shiryayev sequential probability ratio test (SSPRT) is applied to linear dynamic systems for singlefault isolation and estimation. The algorithm turns out to be the multiple model (MM) algorithm considering all thepossible model trajectories. In real application, this algorithm must be approximated due to its increasing computationcomplexity and the unknown parameters of the fault severeness. The Gaussian mixture reduction is employed toaddress the problem of computation complexity. The unknown parameters are estimated in real time by modelaugmentation based on maximum likelihood estimation (MLE) or expectation. Hence, the system state estimation,fault identification and estimation can be fulfilled simultaneously by a multiple model algorithm incorporating these twotechniques. The performance of the proposed algorithm is demonstrated by Monte Carlo simulation. Although ouralgorithm is developed under the assumption of single fault, it can be generalized to deal with the case of (infrequent)sequential multiple faults. The case of simultaneous faults is more complicated and will be considered in future work.

This paper addresses the design, simulation, commissioning and testing of an electrodynamometer (ED) to assessthe dynamic performance of Electric Vehicles (EV). The EV-ED system is comprised of two electric machines coupledmechanically. The traction machine is a 7.75 kW Permanent Magnet Synchronous Motor which is controlled by meansof a vector control and it is coupled mechanically to a similar machine which is used as a mechanical load. The loadmachine was fed by two DC/AC converters connected by the DC bus allowing bidirectional power flow. Theelectrodynamometer was controlled by means of a National Instruments electronic board and Labview software.Several load profiles and inertias were programmed to emulate an Electric Vehicle (EV). The traction machine drivewas implemented with a PP75T120 Powerex Inverter. PWM generation and control strategy were implemented on aMC56F8357 Freescale Digital Signal Controller (DSC). The speed control of the traction machine was validated fordifferent driving cycles. Matlab/Simulink simulations of the machine control and electrodynamometer along withexperimental results illustrating the response of the machine control under the characteristic load profile of an EV arepresented and analyzed. Traction and regenerative breaking stages are analyzed and discussed broadly.

A new class of applications can now be envisaged with the emergence of both mobile ad hoc computing andubiquitous computing, which imposes a number of new unsolved challenges. Examples of such applications includeautomatic car control systems and air traffic control systems. Applications of such kind have real-time constraints andare characterised by being highly mobile and proactive, i.e. able to operate without human intervention. Moreover, thiskind of applications requires multiple-source multicasting. However, current approaches mainly focus on offeringsupport for continuous flows in low mobile environments where single-source multicasting is assumed. In this paper,we present the QoSMMANET (QoS Management in Mobile Ad hoc Networks) framework, which offers QoS supportfor real-time event systems in highly mobile ad hoc environments. Our approach is validated by a number ofexperiments carried out in the ns-2 network simulator.

In this article we propose a collaborative logistics framework for a Port Logistics Chain (PLC) based on the principlesof Supply Chain Management (SCM) that rely on stakeholders integration and collaboration, providing a referencemodel for the inland coordination of the PLC. A comprehensive literature review was conducted, analyzing severalcases in which SCM practices have been implemented as well as studies related to port development, governance,coordination and best practices associated. This background information was used to identify current gaps in logisticsmanagement practices and potential scopes of intervention within the PLC to suggest a redesign process andconfigure new structures under a collaborative scheme, following the guidelines of SCM.

In this work, vibration analysis of rolling element bearings (REBs) defects is studied. The REBs are the most widelyused mechanical parts in rotating machinery under high load and high rotational speeds. When the defect in arolling element comes into contact with another element surface, an impact force is generated which is resulting inan impulsive response of the bearing. A defect at any element of the REB transmits to all other elements such asouter race, inner race, ball and, train cage of the bearing. The defect in rolling elements may lead to seriouscatastrophic consequences resulting in costly downtime. For this purpose, the vibration analysis technique which isa reliable and accurately detecting defect in the bearing elements is used. The vibration data captured and used fordetermination and validation is composed from four different defects states of the REB -outer raceway defect, innerraceway defect, ball defect, and combination of the bearing elements defect- and one representing normal state ofthe bearing for four different running speeds with two load levels. The results obtained from the experiments haveillustrated and explained.

This paper treats the estimation of the state of a nonlinear system with unknown input. The nonlinear system isdescribed by a multimodel with unknown function of activation but depending only on the state. The method of designof the multiobserver is described by using the second method of Lyapunov and their candidate functions. Thesufficient obtained stability conditions are expressed in terms of Linear Matrix Inequalities (LMI) and are obtained firstusing the Lyapunov quadratic functions and secondly by using Lyapunov polyquadratic functions. This latter techniqueseems to be less conservative and less constraining than the first. Illustrative examples are presented in this paper.