Página 9 dos resultados de 473 itens digitais encontrados em 0.032 segundos

Influence of the Operational Constraints in the Active Transmission Losses Allocation via Lagrange Multipliers

BELATI, E. A.; SOUZA, A. M. de; COSTA, G. R. M. da
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
Português
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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.

A New Approach for Video Adaptation through Overlay Services Networks

KOPP, S.; SILVEIRA, R. M.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
Português
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Video adaptation is an extensively explored content providing technique aimed at appropriately suiting several usage scenarios featured by different network requirements and constraints, user`s terminal and preferences. However, its usage in high-demand video distribution systems, such as CNDs, has been badly approached, ignoring several aspects of optimization of network use. To address such deficiencies, this paper presents an approach for implementing the adaptation service by exploring the concept of overlay services networks. As a result of demonstrate the benefits of this proposal, it is made a comparison of this proposed adaptation service with other strategies of video adaptation.

Proposal of a High-Level Language for Writing Self Modifying Programs

SILVA, S. R. B. da; JOSÉ NETO, J.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
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This paper proposes a simple high-level programming language, endowed with resources that help encoding self-modifying programs. With this purpose, a conventional imperative language syntax (not explicitly stated in this paper) is incremented with special commands and statements forming an adaptive layer specially designed with focus on the dynamical changes to be applied to the code at run-time. The resulting language allows programmers to easily specify dynamic changes to their own program`s code. Such a language succeeds to allow programmers to effortless describe the dynamic logic of their adaptive applications. In this paper, we describe the most important aspects of the design and implementation of such a language. A small example is finally presented for illustration purposes.

Electric Power Forecasting Methodologies of Some South American Countries: A Comparative Analysis

Huayllas, Tesoro Elena Del Carpio; Ramos, Dorel Soares
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
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In this paper, a comparative analysis of the long-term electric power forecasting methodologies used in some South American countries, is presented. The purpose of this study is to compare and observe if such methodologies have some similarities, and also examine the behavior of the results when they are applied to the Brazilian electric market. The abovementioned power forecasts were performed regarding the main four consumption classes (residential, industrial, commercial and rural) which are responsible for approximately 90% of the national consumption. The tool used in this analysis was the SAS (c) program. The outcome of this study allowed identifying various methodological similarities, mainly those related to the econometric variables used by these methods. This fact strongly conditioned the comparative results obtained.

Comparison Between Voltage Control Structures of Synchronous Machines

MOTA, D. S.; GOLDEMBERG, C.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
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This paper compares the behaviour of two different control structures of automatic voltage regulators of synchronous machines equipped with static excitation systems. These systems have a fully controlled thyristor bridge that supplies DC current to the rotor winding. The rectifier bridge is fed by the stator terminals through a step-down transformer. The first control structure, named ""Direct Control"", has a single proportional-integral (PI) regulator that compares stator voltage setpoint with measured voltage and acts directly on the thyristor bridge`s firing angle. This control structure is usually employed in commercial excitation systems for hydrogenerators. The second structure, named ""Cascade Control"", was inspired on control loops of commercial DC motor drives. Such drives employ two PIs in a cascade arrangement, the external PI deals with the motor speed while the internal one regulates the armature current. In the adaptation proposed, the external PI compares setpoint with the actual stator voltage and produces the setpoint to the internal PI-loop which controls the field current.

Improvements on the Porter`s Stemming Algorithm for Portuguese

SOARES, M. V. B.; PRATI, R. C.; MONARD, M. C.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
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The amount of textual information digitally stored is growing every day. However, our capability of processing and analyzing that information is not growing at the same pace. To overcome this limitation, it is important to develop semiautomatic processes to extract relevant knowledge from textual information, such as the text mining process. One of the main and most expensive stages of the text mining process is the text pre-processing stage, where the unstructured text should be transformed to structured format such as an attribute-value table. The stemming process, i.e. linguistics normalization, is usually used to find the attributes of this table. However, the stemming process is strongly dependent on the language in which the original textual information is given. Furthermore, for most languages, the stemming algorithms proposed in the literature are computationally expensive. In this work, several improvements of the well know Porter stemming algorithm for the Portuguese language, which explore the characteristics of this language, are proposed. Experimental results show that the proposed algorithm executes in far less time without affecting the quality of the generated stems.

Scheduling Grid Applications with Software Requirements

CHAVES, C. G.; BATISTA, D. M.; FONSECA, N. L. S. da
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
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The aim of task scheduling is to minimize the makespan of applications, exploiting the best possible way to use shared resources. Applications have requirements which call for customized environments for their execution. One way to provide such environments is to use virtualization on demand. This paper presents two schedulers based on integer linear programming which schedule virtual machines (VMs) in grid resources and tasks on these VMs. The schedulers differ from previous work by the joint scheduling of tasks and VMs and by considering the impact of the available bandwidth on the quality of the schedule. Experiments show the efficacy of the schedulers in scenarios with different network configurations.

Robust Hybrid Mechanisms for Scheduling of Grid Tasks

Curi, R. L.; Batista, D. M.; Fonseca, N. L. S. da
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY
Tipo: Artigo de Revista Científica
Português
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This paper proposes three new hybrid mechanisms for the scheduling of grid tasks, which integrate reactive and proactive approaches. They differ by the scheduler used to define the initial schedule of an application and by the scheduler used to reschedule the application. The mechanisms are compared to reactive and proactive mechanisms. Results show that hybrid approach produces performance close to that of the reactive mechanisms, but demanding less migrations.

Design of a Comb Generator for High Capacity Coherent-WDM Systems

Simoes, F. D.; Pataca, D. M.; Rocha, M. L.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY
Tipo: Artigo de Revista Científica
Português
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This paper presents a theoretical model developed for estimating the power, the optical signal to noise ratio and the number of generated carriers in a comb generator, having as a reference the minimum optical signal do noise ratio at the receiver input, for a given fiber link. Based on the recirculating frequency shifting technique, the generator relies on the use of coherent and orthogonal multi-carriers (Coherent-WDM) that makes use of a single laser source (seed) for feeding high capacity (above 100 Gb/s) systems. The theoretical model has been validated by an experimental demonstration, where 23 comb lines with an optical signal to noise ratio ranging from 25 to 33 dB, in a spectral window of similar to 3.5 nm, are obtained.

Riverbed: A Novel User-Steered Image Segmentation Method Based on Optimum Boundary Tracking

Miranda, Paulo A. V.; Falcao, Alexandre Xavier; Spina, Thiago V.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY
Tipo: Artigo de Revista Científica
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This paper presents an optimum user-steered boundary tracking approach for image segmentation, which simulates the behavior of water flowing through a riverbed. The riverbed approach was devised using the image foresting transform with a never-exploited connectivity function. We analyze its properties in the derived image graphs and discuss its theoretical relation with other popular methods such as live wire and graph cuts. Several experiments show that riverbed can significantly reduce the number of user interactions (anchor points), as compared to live wire for objects with complex shapes. This paper also includes a discussion about how to combine different methods in order to take advantage of their complementary strengths.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [09/16428-4, 07/52015-0, 09/11908-8, 11/01434-9]; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Conselho Nacional de Desenvolvimento Cientiacute; Conselho Nacional de Desenvolvimento Cientiacute; fico e Tecnologico (CNPq) [481556/2009-5, 201732/2007-6, 302617/2007-8]; fico e Tecnologico (CNPq)

Introduction to the Software-defined Radio Approach

Selva, André F. B.; Reis, André L. G.; Lenzi, Karlo G.; Meloni, Luis Geraldo Pedroso; Barbin, Silvio Ernesto
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY
Tipo: Artigo de Revista Científica
Português
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Telecommunications have been in constant evolution during past decades. Among the technological innovations, the use of digital technologies is very relevant. Digital communication systems have proven their efficiency and brought a new element in the chain of signal transmitting and receiving, the digital processor. This device offers to new radio equipments the flexibility of a programmable system. Nowadays, the behavior of a communication system can be modified by simply changing its software. This gave rising to a new radio model called Software Defined Radio (or Software-Defined Radio - SDR). In this new model, one moves to the software the task to set radio behavior, leaving to hardware only the implementation of RF front-end. Thus, the radio is no longer static, defined by their circuits and becomes a dynamic element, which may change their operating characteristics, such as bandwidth, modulation, coding rate, even modified during runtime according to software configuration. This article aims to present the use of GNU Radio software, an open-source solution for SDR specific applications, as a tool for development configurable digital radio.

Java Cryptographic Library for Smartphones

Okida, C.; Goya, D.; Terada, R.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY
Tipo: Artigo de Revista Científica
Português
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A JME-compliant cryptographic library for mobile application development is introduced in this paper. The library allows cryptographic protocols implementation over elliptic curves with different security levels and offers symmetric and asymmetric bilinear pairings operations, as Tate, Weil, and Ate pairings.

Rigid and non-rigid point-based medical image registration

Parra, Nestor Andres
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
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The primary goal of this dissertation is to develop point-based rigid and non-rigid image registration methods that have better accuracy than existing methods. We first present point-based PoIRe, which provides the framework for point-based global rigid registrations. It allows a choice of different search strategies including (a) branch-and-bound, (b) probabilistic hill-climbing, and (c) a novel hybrid method that takes advantage of the best characteristics of the other two methods. We use a robust similarity measure that is insensitive to noise, which is often introduced during feature extraction. We show the robustness of PoIRe using it to register images obtained with an electronic portal imaging device (EPID), which have large amounts of scatter and low contrast. To evaluate PoIRe we used (a) simulated images and (b) images with fiducial markers; PoIRe was extensively tested with 2D EPID images and images generated by 3D Computer Tomography (CT) and Magnetic Resonance (MR) images. PoIRe was also evaluated using benchmark data sets from the blind retrospective evaluation project (RIRE). We show that PoIRe is better than existing methods such as Iterative Closest Point (ICP) and methods based on mutual information. ^ We also present a novel point-based local non-rigid shape registration algorithm. We extend the robust similarity measure used in PoIRe to non-rigid registrations adapting it to a free form deformation (FFD) model and making it robust to local minima...

The acquisition, signal processing and analysis of epicardial surface electrograms from rabbit heart

Kim, Steven Jon
Fonte: Universidade Rice Publicador: Universidade Rice
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The activation sequence on the epicardial surface of the in vivo rabbit ventricle has been recorded and analyzed under conditions of normal sinus rhythm and controlled hemodynamic load. Data for the analysis was gathered sequentially using a personal computer $PC$-based 32-channel data acquisition system that was connected via a switching system to pressure and flow transducers and an epicardial sock containing 120 electrodes arranged in cylindrical coordinates of 8 rows and 15 columns. The adequacy of temporal and two-dimensional spatial sampling was analyzed, providing the theoretical basis for the application of (1) various digital signal processing methods for conditioning the data, and (2) a Fourier method for constructing high resolution epicardial isopotential and isochronal contour maps. These maps provide a useful tool for analyzing the spatial and temporal aspects of ventricular epicardial activation. Observed patterns of excitation were compared and found to correlate with the results of anatomical studies of the specialized conduction system.

Remote control of a robotic arm through speaker-dependent, isolated-word speech recognition

Atkinson, William Thomas
Fonte: Universidade Rice Publicador: Universidade Rice
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The focus of this thesis is the remote control of a six degree-of-freedom mid-range industrial robot arm through the use of speech recognition. The robot arm is controlled through speaker-dependent, isolated-word speech recognition. Template matching techniques are used to interpret verbal input and make the robot arm perform a desired task. The user inputs one- or two-word commands to interact verbally with the robot. The verbal input is matched against a vocabulary of known commands for recognition. Once the command is interpreted, the corresponding subroutine is run and the robot arm performs the task. The movement of the arm, to include the manipulation of its gripper, is accomplished in discrete increments. The program is designed to allow for multiple users and it can be modified to perform robotic control for other tasks.

Modeling process scheduling and system software in multiprocessors

Debbad, Vijay Kumar
Fonte: Universidade Rice Publicador: Universidade Rice
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This thesis presents new techniques for simulating multiprogramming and interrupt servicing in an execution driven simulation environment. We have incorporated these techniques into the Rice Parallel Processing Testbed (RPPT), a powerful tool for simulating and analyzing parallel computer systems and algorithms. A new approach for modeling system software overheads on the RPPT is also described. As part of this study, we validate the RPPT against a distributed system running the V operating system and outline possible applications of the system. The model of the distributed system makes use of the new interrupt and timeslicing capabilities of RPPT, and the capability to assign priorities to processes. The implementation of a separate operating system module for the architecture is shown to be effective in the correct simulation of the software overheads and in the logical division of the simulation environment.

Fault detection and fault tolerance methods for robotics

Visinsky, Monica Lynn
Fonte: Universidade Rice Publicador: Universidade Rice
Português
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517.20062%
Fault tolerance is increasingly important in modern autonomous or industrial robots. The ability to detect and tolerate failures allows robots to effectively cope with internal failures and continue performing designated tasks without the need for immediate human intervention. To support these fault tolerant capabilities, methods of detecting and isolating failures must be perfected. This thesis presents new fault detection algorithms which detect failures in robot components using analytical redundancy relations. The robot components critical to fault detection are revealed using an extended fault tree analysis. The thesis validates the algorithms using a simulated robot failure testbed. An intelligent fault tolerance framework is proposed in which a fault tree database and the detection algorithms work together to detect and tolerate sensor or motor failures in a robot system. Future work will expand the detection and tolerance routines and embed the framework into a more flexible expert system package.

IDM - A New Parallel Methodology to Calculate the Determinant of Matrices of the Order n, with Computational Complexity O(n)

Menezes, Marlim Pereira; Pereira, Carlos Eduardo de Morais; Sato, Liria Matsumoto
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY
Tipo: Artigo de Revista Científica
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This paper presents a new parallel methodology for calculating the determinant of matrices of the order n, with computational complexity O(n), using the Gauss-Jordan Elimination Method and Chio's Rule as references. We intend to present our step-by-step methodology using clear mathematical language, where we will demonstrate how to calculate the determinant of a matrix of the order n in an analytical format. We will also present a computational model with one sequential algorithm and one parallel algorithm using a pseudo-code.

GeoHealth: A Georeferenced System for Health Data Analysis in Primary Care

Sa, J. H. G.; Rebelo, M. S.; Brentani, A.; Grisi, S.; Gutierrez, M. A.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY
Tipo: Artigo de Revista Científica
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The Primary Care Information System (SIAB) concentrates basic healthcare information from all different regions of Brazil. The information is collected by primary care teams on a paper-based procedure that degrades the quality of information provided to the healthcare authorities and slows down the process of decision making. To overcome these problems we propose a new data gathering application that uses a mobile device connected to a 3G network and a GPS to be used by the primary care teams for collecting the families' data. A prototype was developed in which a digital version of one SIAB form is made available at the mobile device. The prototype was tested in a basic healthcare unit located in a suburb of Sao Paulo. The results obtained so far have shown that the proposed process is a better alternative for data collecting at primary care, both in terms of data quality and lower deployment time to health care authorities.

Multifunctional Three-Dimensional Nanoelectronic Networks for Smart Materials and Cyborg Tissues

Dai, Xiaochuan
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation; text Formato: application/pdf
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Nanomaterials provide unique opportunities at the interface between nanoelectronics and biology. “Bottom-up” synthesized nanowire(NW) with defined functionality can be assembled and enabled into three-dimensional(3D) flexible nanoelectronic networks. The micro- to nanoscale electronic units blur the distinction between electronics and cells/tissue in terms of length scale and mechanical stiffness. These unconventional 3D nanoelectronic networks can thus provide a path towards truly seamless integration of non-living electronics and living systems. In this thesis, I will introduce a general method for fabricating 3D macroporous NW nanoelectronic networks and their integration with hydrogel, elastomer and living tissues, with an emphasis on the realization of two-way communication between active nanoelectronics and the passive or living systems in which they are embedded. First, fabrication of 3D macroporous NW nanoelectronic networks will be described. Examples showing hundreds of individually addressable, multifunctional nanodevices fully distributed and interconnected throughout 3D networks will be illustrated. Proof-of-concept studies of macroporous nanoelectronic networks embedded through hydrogels and polymers demonstrate the ability for dynamically mapping pH gradients and strain fields. Second...