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Latin America Transactions, IEEE (Revista IEEE America Latina)

Issue 1 • Date March 2010

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Displaying Results 1 - 15 of 15
  • Channel Reliability for Turbo DS/CDMA Systems under Rayleigh Fading and Multiple Access Interference

    Publication Year: 2010 , Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    This work proposes a general equation for the channel reliability (Lc) of turbo code in DS/CDMA systems under flat fading channels and multiple access interference. The proposed reliability equation is suitable for prediction under low, medium as well high signal-noise ratio (SNR) operation system. The channel reliability equation was established as a function of system loading and SNR from fitting of Monte-Carlo simulation (MCS) performance results. View full abstract»

    Open Access
  • Moving Average Hybrid Filter to the Enhancing Ultrasound Image Processing

    Publication Year: 2010 , Page(s): 9 - 16
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1493 KB)  

    In this work, we present a novel technique for ultrasound image processing. The development is carried out trough of the finite impulse response filter (FIR) and the Taylor polynomial approximation. Here, we showed the generic form of the Moving Average Hybrid filter (MAH) to the enhancing ultrasound imaging. Finally, we present any evaluations qualitative and quantitative to the improvement of MAH filter. View full abstract»

    Open Access
  • Platform for evaluation of control strategies of functional stimulators through the EMG of the same stimulated muscle

    Publication Year: 2010 , Page(s): 17 - 22
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1021 KB)  

    The development of a platform for the evaluation of control algorithms of functional stimulators commanded by the surface electromyogram of the same electro-stimulated muscle is described. It is conformed by a stage of conditioning and other processing. The first carries out the removal of the electrical stimulus artifact and the amplification and filtering of the signal. The second stage provides a processing environment for the implementation of algorithms and allows the creation of a control signal to the stimulator. The prototype was tested with simulated and real signals, evaluating the removal of the artifact, signal amplification, the frequency response of the filters, adquisition and storage of data. The results showed good performance of the artifact's suppressor, very good SNR of the signal conditioned and high reliability in storing the digitized data, obtaining a suitable tool for rapid assessment of algorithms. View full abstract»

    Open Access
  • Using Random Restart Hill Climbing Algorithm for Minimization of component Assembly Time Printed Circuit Boards

    Publication Year: 2010 , Page(s): 23 - 29
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (734 KB)  

    This paper presents an heuristic for minimization of the mounting time of components in a printed circuit board using the random restart hill climbing method. The mounting problem is divided in four different and interrelated sub problems: definition of the mounting sequence in the printed circuit board, definition of the distribution of the components in the magazines, definition of the capture sequence, definition of the nozzles sequence. The random restart hill climbing method is used in two different times. In a first time to make a global optimization of the mounting sequence and of the distribution sequence in the magazines. In a second time, to optimize the mounting sequence and the capture sequence in each capture-mounting sequence cycle. The results show that the mounting time simulated in a real machine is better for the minimized sequence proposed by the heuristic than for others sequences proposed in the literature. View full abstract»

    Open Access
  • Widely Linear Adaptive Equalization of Digital Communication Channel

    Publication Year: 2010 , Page(s): 30 - 37
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (591 KB)  

    In this paper, we employ the widely linear adaptive processing technique in digital communication channel equalization. We present two new techniques for supervised and unsupervised equalization. In the supervised technique the multi-split transform is aggregated to the widely linear processing, using a power normalized and time-varying step-size LMS algorithm. The unsupervised technique consists of a widely linear adaptive prediction-error filter using the time-varying step-size LMS algorithm proposed by Kwong and Johnston. We show that this technique can invert non-minimum phase channels. The main advantages of the proposed equalizers are the low computational complexity and better performance in terms of convergence rate and accuracy, when compared to the conventional equalization techniques. Simulation results show that the widely linear equalizers have a good performance. View full abstract»

    Open Access
  • A New Approach to Remuneration of Ancillary Services Provided by Generation Agents in Brazil

    Publication Year: 2010 , Page(s): 38 - 44
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (474 KB)  

    The restructuring of electrical sector based on the market resulted in the separation of generation, transmission and distribution agents and in the operation costs discrimination. This process lead to the necessity to separate the different services provided by the agents with the objective of organize by function and to define methodologies to identify who offers and who uses these services, as well as methodologies of remuneration to same ones. In this way, the present work presenting studies and methodologies to remunerate some Ancillary Services, such as: Black-start, Active Power Reserve, Special Protection Systems and Reactive Power Support. The studies and methodologies proposed were accomplished starting from the Ancillary Services provided by large Brazilian generation agents. View full abstract»

    Open Access
  • Evolution of oscillograph - How did Chesf transform data into information?

    Publication Year: 2010 , Page(s): 45 - 50
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (836 KB)  

    A brief historical review of the implementation of the oscillographic network of Companhia Hidro Eletrica do Sao Francisco (CHESF), which considers the influence of technological advances in all stages of the process, from design to the current configuration of the network is presented. Some problems and their solutions implemented deserved attention, with an emphasis on software of oscillographic analysis that resulted from a Project of Research and Development developed by the Federal University of Campina Grande (UFCG). View full abstract»

    Open Access
  • Fuzzy Control System for Voltage Regulation In Power Transformers

    Publication Year: 2010 , Page(s): 51 - 57
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (839 KB)  

    A fuzzy control strategy for voltage regulation in electric power distribution systems is introduced in this article. This real-time controller would act on power transformers equipped with under-load tap changers. The fuzzy system was employed to turn the voltage-control relays into adaptive devices. The scope of the present study has been limited to the power distribution substation, and both the voltage measurements and control actions are carried out on the secondary bus. The capacity of fuzzy systems to handle approximate data, together with their unique ability to interpret qualitative information, make it possible to design voltage control strategies that satisfy both the requirements of the Brazilian regulatory bodies and the real concerns of the electric power distribution companies. A prototype based on the fuzzy control strategy proposed in this paper has also been implemented for validation purposes and its experimental results were highly satisfactory. View full abstract»

    Open Access
  • Influence of the Operational Constraint in the Active Transmission Losses Allocation Via Lagrange Multipliers

    Publication Year: 2010 , Page(s): 58 - 64
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (458 KB)  

    This paper presents an approach for the active transmission losses allocation between the agents of the system. The approach uses the primal and dual variable information of the Optimal Power Flow in the losses allocation strategy. The allocation coefficients are determined via Lagrange multipliers. The paper emphasizes the necessity to consider the operational constraints and parameters of the systems in the problem solution. An example, for a 3-bus system is presented in details, as well as a comparative test with the main allocation methods. Case studies on the IEEE 14-bus systems are carried out to verify the influence of the constraints and parameters of the system in the losses allocation. View full abstract»

    Open Access
  • Neural Network-Based Approach for Identification of the Harmonic Content of a Nonlinear Load in a Single-Phase System

    Publication Year: 2010 , Page(s): 65 - 73
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (718 KB)  

    In this paper an alternative method based on artificial neural networks is presented to determine harmonic components in the load current of a single-phase electric power system with nonlinear loads, whose parameters can vary so much in reason of the loads characteristic behaviors as because of the human intervention. The first six components in the load current are determined using the information contained in the time-varying waveforms. The effectiveness of this method is verified by using it in a single-phase active power filter with selective compensation of the current drained by an AC controller. The proposed method is compared with the fast Fourier transform. View full abstract»

    Open Access
  • Accounting Management Based on Quality of Service for Heterogeneous Mobile Communications Networks

    Publication Year: 2010 , Page(s): 74 - 81
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1284 KB)  

    Service Accounting Management within the new heterogeneous advanced mobile communications networks environment will be one of the great challenges to resolve from the point of view of service providers. The objective will be to maximize resource utilization and the economic benefits obtained. In the near future, service providers may make use of a combination of different technologies access to offer users a wide variety of innovative services, characterized by the demand for different requirements of quality of service (QoS). Furthermore, users can select appropriate to your preferences service provider. Within this scenario, service accounting management will become an effective tool that allows meet the demands of users and maximize the profits of providers. In this article we present a proposal for charging based on QoS that allows increase the level of satisfaction of the user at a first instance, maximizing the level of provided CdS, and a second instance implementing adaptable price strategies at the level of offered QoS management. These strategies allow service providers to maximize obtained profits. View full abstract»

    Open Access
  • Analysis and Implementation Hardware-Software of Rijndael Encryption

    Publication Year: 2010 , Page(s): 82 - 87
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    By means of this study We have optimized the performance of the cryptographic algorithm Rijndael in a low cost hardware/software system, in a FPGA Spartan3e board of Xilinx with a MicroBlaze soft-processor. After the study of its execution in six systems with different configurations, the hardware bits rotation of MicroBlaze's optimizes the process of coding and deciphered, and the combination with the implementation of a coprocesador with a Galois field multiplier optimizes the key expansion. View full abstract»

    Open Access
  • Clustering Method for Social Network Annotations

    Publication Year: 2010 , Page(s): 88 - 93
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    Folksonomies are a widely used tool of collaboratively creating and managing tags to annotate and categorize Internet resources (Web 2.0). The process of annotation and tag management by users of social networks is extremely easy and simple; however, it involves serious problems of navigation and search unlike what happens with taxonomies, thesauri and ontologies. The use of fuzzy similarity measures allows the correct identification of syntactic variations when tag lengths are greater or equal than five symbols, been inadequate for smaller length tags. This article presents a method that combines both fuzzy similarity and cosine measures in order to provide a proper classification of tags even with smaller tag lengths. This method allows the proper classification of the 95% of the syntactic variations of tags analyzed in the experiments. View full abstract»

    Open Access
  • Identifying potential coupling sources in the x86 instruction set

    Publication Year: 2010 , Page(s): 94 - 100
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (867 KB)  

    Computer languages design is a fundamental subject in Computer Science and instruction sets are not an exception. Considering concurrency, and particularly superscalar processing, an important fact is to identify those characteristics of the instruction set architecture that may cause extra code coupling. Because of its current extended use, the x86 instruction set was chosen for analysis. We present a study of the use distribution of architectonic registers, including implicit usage, taken from execution traces of a test bench. Then we identify as potential coupling sources the implicit and dedicated use of certain registers, condition codes utilization and some mechanisms of effective memory address computation. View full abstract»

    Open Access
  • Reducing the Setup of a Tubettes Machine

    Publication Year: 2010 , Page(s): 101 - 106
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (828 KB)  

    This manuscript deals with the manufacturing process of tubettes (tubes made by gluing strips of paper), whose preparation of tubettes machine occupies a considerable portion of production time. The paper strips are packed in paper reels and some of them may be used between one and making another tubettes. Two mathematical models for the minimization of change reels are shown. The results obtained by simulations with the solver Xpress-MP were better than those used by the company, with reductions of up to 37% in the number of changes. View full abstract»

    Open Access

Aims & Scope

IEEE Region 9 provides IEEE Latin America Transactions to enable the publication of non-published and technically excellent papers from Latin American engineers, in Spanish or Portuguese languages.

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