Recursos de colección

Repositório Comum (25.334 recursos)

É um repositório para instituições de ensino e investigação produtoras de literatura científica cuja dimensão ainda não justifica a criação de um repositório próprio. Permite integrar instituições, grupos ou indivíduos na infra-estrutura do projecto, nomeadamente através das pesquisas do Portal RCAAP e da B-On.

IPS - ESTS – DEE - Comunicações em congressos

Mostrando recursos 1 - 20 de 21

  1. Robot localization from minimalist inertial data using a Hidden Markov Model

    Abreu, António
    Hidden Markov Models (HMM) are applied to interoceptive data (in this case the sense of rotation by way of a gyroscope) acquired by a moving wheeled robot when contouring an indoor environment. We demonstrate the soundness of HMM to solve the problem of robot localization in a topological model of the environment, particularly the kidnapped robot problem and position tracking. In this approach, the environment topology is described by the sequence of movements a robot executes when contouring the environment. Movements are described in a fuzzy domain using distance traveled and curvature as features.

  2. Implementation of a low cost data acquisition board for photovoltaic arrays analysis and diagnostic

    Sousa, Sérgio; Onofre, Maicon; Antunes, Tiago; Branco, Cláudio; Maia, José; Inacio-Rocha, Jose; Pires, V. Fernão
    Testing PV modules are one of the important procedures to ensure the conformity with the standards and quality of this equipment’s. To implement some of the PV modules tests a data acquisition system is required. This paper presents the design and implementation of a data acquisition system for photovoltaic systems. The developed system is characterized by a low cost board based on a microcontroller. The description of the hardware as well an application to test its performance is presented. The developed system can be used for reading, storing and analyzing information from several photovoltaic systems. Experimental tests are presented to...

  3. A Network and Repository for Online Laboratory based on Ontology

    Saliah-Hassane, Hamadou; Correia, Raúl Cordeiro; Fonseca, José Manuel
    Our propose is to build a network of virtual laboratories and also use it as a global repository of online laboratory’s and experiences. This set of virtual and online laboratories can be “stored” in an “virtual closet”, and also the system will allow us to build new experiences and online laboratories, and store them is this “virtual closet”. With the drawing of this new standard we pretend define methods for storing and retrieving learning objects for remote laboratories. The objective of this standard is also define methods for linking learning objects to design and implement smart learning environments for remote...

  4. Ontology: a support structure for a V-Labs Network, the Euronet - Lab

    Correia, Raúl Cordeiro; Fonseca, José Manuel; Donnellan, Andrew
    This paper presents work on the establishment of a virtual laboratories network, based on the concept of Virtual Closet that will contain all the elements and parts required to build the different experiences available in a vlabs network (that we call Euronet-Lab). To build this complex network it is necessary to find an adequate support. The large database of v-labs and independent elements that can integrate this structure allows the “recycling” of elements for purposes diverse from those they were originally created. This means to “re-use” the same element several times in different scenarios. In order to do this, it...

  5. Euronet Lab, A Cloud V-Lab Enviroment

    Correia, Raúl Cordeiro; Fonseca, José Manuel
    In this paper we present a proposal for the creation of a European V-labs web space. In its essence it would result in an open online laboratory, with a primarily practical nature. In this laboratory students will have the opportunity to develop skills in the “know-how-to-do” area, enabling them to conduct a series of practical experiences in “try-out” philosophy that will substantiate and consolidate all knowledge that the students acquired in lectures. It is quite possible that these resources aren’t available in all universities and institutions, specifically in the university where the student is. This environment provides substance to the...

  6. The use of an ontology as support of a virtual lab and remote labs network Euronet - Lab

    Correia, Raúl Cordeiro; Fonseca, José Manuel; Donnellan, Andrew
    Our propose is to build a network of virtual laboratories, based in a Virtual Closet that will contain all the elements and parts that are needed to build the various experiences available in a v-labs network (that we call Euronet-Lab). To build this complex network we need to find a system that supports effectively this structure. This probably will be a enormous database of v-labs and independent elements, where will be possible sometimes to “recycle” some of the elements. This means “re-use” the same element several times in many experiences. To do this is necessary to have a structure that...

  7. Euronet Lab : a Cloud Based Laboratory Environment

    Correia, Raúl Cordeiro; Fonseca, José Manuel; Donnellan, Andrew
    A large number of virtual and remote labs connected to the internet is already available nowadays. However, they usually are isolated and independent systems, unable to cooperate and complement each other. This lack of interconnection and interoperability leads, consequently, to the duplication of efforts in order to develop what could be easily shared and reused. Therefore, the integration of different platforms can speed up the development of virtual labs and downsize the barriers of using complementary systems that would represent an unachievable development task. In this paper one presents a proposal for the implementation of an open system that will be...

  8. Road Motion Control Electric Vehicle with Speed and Torque Observer

    Foito, Daniel; Gaspar, Manuel; Pires, V. Fernão
    This paper presents an electric vehicle (EV) with two independent rear wheel drives and with an electric differential system. A model of the vehicle dynamic model is presented. The electric differential was implemented assuring that, in straight right trajectory, the two wheels drives roll exactly at same velocity and, in curve, the difference between the two velocities assure a vehicle trajectory. A speed and torque observer for DC motor was also proposed and simulated. Analysis and simulation results of the proposed system are presented.

  9. An Adaptive PID Speed Controller for an 8/6 Switched Reluctance Machine

    Rafael, Silviano; Santos, P. J.; Pires, A. J.
    This paper presents a classical controller with parameters adaptation capability, in an automatic way. This controller is based on a PID where a parameters adaptation algorithm is used and applied to the switched reluctance motor (SRM) speed control. This PID design do not require any kind of adjustment or calibration from the operator. The parameters adaptation algorithm implemented is based on one fuzzy system with a Takagi-Sugeno inference mechanism with some simplifications. These simplifications had the goal to select the parameters adaptation algorithm contributing for a fast controller response. The developed adaptive PID algorithm was modelled and simulated.

  10. Load forecasting, the importance of the probability “tails” in the definition of the input vector

    Santos, P. J.; Rafael, Silviano; Pires, A. J.
    The load forecast is part of the global management of the electrical networks, namely at the transport and distribution levels. This type of methodologies allows to the system operator, to establish and take some important decisions concerning to the mix production and network management, with the minimum of discretionarity. The load forecast in particularly the peak load forecast, represents an important economic improvement in the global electrical systems. Also in certain circumstances, allow reducing the contribution of the non-renewable units, in the daily mixing production. The regressive methodologies specially the artificial neural networks, are normally used in this type of...

  11. Fast and secure automatic retrieval of data from multi-vendor devices - The portuguese experience

    Louro, Miguel; Guisado, Jaime; Fortunato, Carlos; Cura, Carlos; Antunes, Bruno; Areias, Miguel; Grossinho, Miguel; Pereira, Luís Pinto; Pimenta, Fernando
    Nowadays protection systems generate large amounts of useful data. The most important of which are the oscillographic records, because they allow: fault location estimation; validation of relay settings; validation of coordination among protections. This important information traditionally resided in the protection units and could only be retrieved through vendor proprietary software. Retrieving this information could be conducted in two ways: a specialized technician had to physically go to the substation (expensive solution); by use of a slow analog modem with a tendency to breakdown (especially in remote areas exposed to lightning strikes) and a high probability to stop working due...

  12. Distribution automation on LV and MV using distributed intelligence

    Melo, Francisco; Cândido, Carlos; Fortunato, Carlos; Silva, Nuno; Campos, Filipe; Reis, Paulo
    Nowadays, the electrical energy distribution network is considered to be a critical infrastructure in industrially developed societies. Its protection regarding safety and security threats is increasing awareness and concern.The fact that this infrastructure is geographically spread across large areas brings difficult technological challenges for fault management (real-time prevention, detection, precise location and isolation of anomalies). The distribution automation and fault location in the distribution network is a key task for any operator. Distribution Automation (DA) and electric network monitoring and sensing can reduce outage and repair times, optimise voltage profiles and improve asset management. Advanced DA processes real-time information from...

  13. A current differential line protection using a synchronous reference frame approach

    Martins, L. Sousa; Fortunato, Carlos; Pires, V. Fernão
    This paper presents a new approach for a current differential protection of the transmission lines. This approach is based on the Park transformation or ABC-dqo transformation. Using the ABC-dqo transformation the three phase quantities are transformed into a synchronous rotating reference frame. In this way, the line currents of the three phase system are measured and transformed into three dc components. So, immunity to problems such as sampling misalignment and time delay of the communication channel will be improved. Several test results are presented in order to show the effectiveness of the proposed approach.

  14. A power amplifier system for testing of distance relay operating characteristic

    Marçal, Rui; Rodrigues, Ricardo; Fortunato, Carlos; Martins, L. Sousa; Pires, V. Fernão
    This paper describes a power amplifier system for testing of distance relay operating characteristic. This power amplifier is based on two three phase inverters with a neutral wire. The output power currents and voltages are controlled by a sliding mode controller. A developed matlab/simulink digital simulator generates the test signals. This test signals are converted in current and voltage references using a microcontroller to connect the digital simulator to the power converter amplifier. Experimental results from a laboratory prototype are presented and discussed.

  15. Transmission lines protection based on the current eigenvalues differential concept

    Pires, V. Fernão; Guerreiro, M.; Fortunato, Carlos; Martins, L. Sousa
    This work presents a new approach for a current differential protection of the transmission lines. The proposed approach is based on the Clarke-Concordia transformation and principal component analysis. First the acquired current signals are transformed into “αβo” components by applying the Clarke-Concordia transformation. This allows obtaining typical patterns. To identify these patterns a principal component analysis is performed. Several tests under different fault conditions were performed. The obtained results allow verifying the effectiveness of the proposed approach.

  16. Energy and quality of service management in wireless multimedia sensor networks

    Pereira, Paulo; Gonçalves, José; Grilo, António; Fortunato, Carlos; Nunes, Mário; Casaca, Augusto
    Sensor networks are composed of resource constrained nodes that capture data from the environment, preprocess it and then transmit it to a sink node. This paper presents a scenario for monitoring an electricity distribution network, an energy analysis of the used sensor nodes and an intelligent energy and quality of service (QoS) manager. This manager continuously adapts the provided QoS according to the energy level of the nodes.

  17. A wireless sensors suite for Smart Grid applications

    Grilo, António; Sarmento, Helena; Nunes, Mário; Gonçalves, José; Pereira, Paulo; Casaca, Augusto; Fortunato, Carlos
    This paper presents a demonstrator of a Wireless Sensor and Actuator Network (WSAN) for Smart Grid applications, developed in the context of project WSAN4CIP. This WSAN is formed by WSAN nodes equipped with sensors and a wireless radio interface, which monitor key parameters of power grid equipments belonging to the Medium Voltage (MV) and Low Voltage (LV) segments. The measurements are reported to the SCADA system and constitute the basis of both safety and security services to improve the power grid distribution dependability. This paper describes the hardware of the sensor nodes and presents the respective performance results, attesting the...

  18. A wireless sensors suite for Smart Grid applications

    Grilo, António; Sarmento, Helena; Nunes, Mário; Gonçalves, José; Pereira, Paulo; Casaca, Augusto; Fortunato, Carlos
    This paper presents a demonstrator of a Wireless Sensor and Actuator Network (WSAN) for Smart Grid applications, developed in the context of project WSAN4CIP. This WSAN is formed by WSAN nodes equipped with sensors and a wireless radio interface, which monitor key parameters of power grid equipments belonging to the Medium Voltage (MV) and Low Voltage (LV) segments. The measurements are reported to the SCADA system and constitute the basis of both safety and security services to improve the power grid distribution dependability. This paper describes the hardware of the sensor nodes and presents the respective performance results, attesting the...

  19. Current differential line protection using a pattern recognition method

    Pires, V. Fernão; Fortunato, Carlos
    This paper presents a new approach to a numerical current differential protection for the transmission lines. The current differential algorithm uses a pattern recognition method. First the acquired current signals are transformed into “dqo” components by applying the Park transformation. The transformed currents will originate typical patterns according the fault type. Using a pattern recognition algorithm the different faulty conditions are identified. Several tests under different fault conditions were performed. The obtained results allow verifying the effectiveness of the proposed approach.

  20. Fault location in an electrical energy distribution infrastructure with a wireless sensor network

    Fortunato, Carlos; Casaca, Augusto; Grilo, António; Santos, Miguel
    This paper presents a detailed analysis of the applicability of wireless systems in the localization of faults in the energy distribution network. The hardware and software architectures of the envisaged sensor solution will also be described and finally, the integration of this system into Smart Grids will be discussed in terms of automatic fault analysis. A pilot system has been tested in a subset of the Portuguese energy distribution infrastructure operated by EDP Energias de Portugal. It presents a new approach to a fault locator system for the power network. The purpose is to obtain faster and more reliable information...

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