Navegando por Assunto "Sistemas embarcados"

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
Desenvolvimento, implementação e testes de um sistema de comunicação sem fio heterogêneo para acesso à serviços: aplicações na telemedicina e domótica
(Universidade Federal do Pará, 2011-01-31) SATO, Roberto Masanori Vale; CASTRO, Agostinho Luiz da Silva; http://lattes.cnpq.br/2798180168487751
In the last 20 years, economy and technology have evolved in many directions and into new areas. Many of these developments have created opportunities that are being considered in the conception of future communication networks. These new possibilities are related to, specially, use the internet to access services and include: mobility, low cost technologies, growth and jobs (over the Internet it is possible to participate in each business process and production) services, education (opportunity for people to grow and thrive), entertainment (virtual worlds for entertainment, shopping and games), a high traffic volume (text, voice, images, video). As a result, the Internet has become, like electricity or water, a public good. With almost 2 billion of users (about 28% of world population), the Internet is becoming, increasingly, a pervasive infrastructure providing anywhere and anytime connectivity and services. This world of the Internet current is the result of successive changes that have occurred since its inception and became the communications infrastructure of critical importance. In terms of communication technologies, mobile wireless systems have a special place because of its exceptional propagation in the last decade and, along with the Internet, has allowed the emergence of smart devices, the introduction of new innovative services and demand for an environment that supports innovation and creativity. However, the various network standards to support, mainly to access to last mile are disadvantages to the user's perspective, because it has to enable these networks (to contract the services) and often to have specific terminals to access them. The idea of a single standard for these networks did not achieve satisfactory results and a solution points for the integration of these networks to provide unique and transparent access to the user. This paper therefore presents an embedded solution for integrating wireless communications standards such heterogeneous IEEE 802.15.4 ZigBee, IEEE 802.20 GSM / GPRS and Wi-Fi IEEE 802.2. This heterogeneity of wireless technologies enables a user moving through your local or remote terminal access applications and services in the transparent way. Performance evaluation of the solution was performed using two types of services: home automation and telemedicine. The results indicated that the proposed solution can integrate and provide services with safety and reliability.
Acesso aberto (Open Access)
Investigação experimental de estratégias de identificação e controle LPV aplicadas ao amortecimento de oscilações eletromecânicas em sistemas elétricos de potência
(Universidade Federal do Pará, 2012-06-29) NOGUEIRA, Fabrício Gonzalez; BARREIROS, José Augusto Lima; http://lattes.cnpq.br/1246564618922453; BARRA JUNIOR, Walter; http://lattes.cnpq.br/0492699174212608
In this thesis is performed an experimental investigation of the performance of a LPV (linear parameter varying) control strategy applied to damp electromechanical oscillations in electric power systems. The study was performed in a 10kVA electric power system, which is configured as a single machine connected to an infinite bus. Furthermore, were also performed field tests on a generating unit of Tucurui Hydroelectric Power Plant. Firstly, a set of routines for the analysis and synthesis of LPV damping controllers were developed and tested computationally, along with routines for the identification of LPV models of the plant. The coefficients of the LPV damping controller, in this case a power system stabilizer (PSS), depends on the value of a variable representative of the system operating condition (scheduling parameter), which in this study, were the terminal active power (P) and reactive power (Q) of the generating unit. For control ends, the dynamics of the plant was represented by an ARX LPV model, which was estimated from experimental data collected in the plant for a wide range of operating conditions. From the LPV model of the plant, the values of the parameters of the LPV controller were determined via an optimization problem, in the form of a parameterized LMI (PLMI). The solution of PLMI is obtained from a relaxation via sum-of-squares decomposition. The LPV PSS was designed to ensure stability and performance for a wide range of operating conditions of the plant, which is generally not possible to obtain with conventional fixed parameter controllers. The LPV PSS control law was implemented in an embedded system based on a digital signal controller. The experimental results showed an excellent performance of the LPV PSS on the damping of the electromechanical oscillations both in the 10kVA electric microgenerator system, and in the Tucurui generating unit.
Acesso aberto (Open Access)
Proposta e avaliação de um sistema assistivo para auxílio da pessoa com deficiência visual na seleção de produtos
(Universidade Federal do Pará, 2019-05-24) SILVA, Andrei Luiz Demetrio e; MERLIN, Bruno; http://lattes.cnpq.br/7336467549495208; FÜLBER, Heleno; http://lattes.cnpq.br/5018616409948511
The act of making purchases is seen as a simple task for most people. However, for someone with visual impairment it can mean something complex or even impossible to realize without the help of others. In order to overcome this barrier and enable the realization of the selection of products in an autonomous way by the visually impaired, the proposed system was developed. Using a microcontroller interconnected to a radio frequency sensor and an audio reproducer, an embedded system (coupled to a glove) was built, which together with a database query service made possible its implantation. Its use was evaluated by two groups of participants through the accomplishment of a case study set in a supermarket. The first group consisted only of visually impaired, while the second group was blind sighted participants, who were blindfolded to simulate newly acquired blindness. With the accomplishment of this work, it was possible for people with visual impairment to perform a product selection process autonomously, reaching a mean assertiveness index of 92.5%.
Acesso aberto (Open Access)
Sistema de aquisição de dados para monitoramento de malha de terra energizada
(Universidade Federal do Pará, 2015-11-18) SOUSA, Kleiber Tenório de; TOSTES, Maria Emilia de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
The good performance of grounding system in substations and generating plants is an essential condition for their operation according with established quality standards. Therefore a continuous monitoring system for grounding grid is an important tool to aid technical teams to identify failed zones that depreciate the Power Systems operation. Some traditional measuring methods in grounding grids need the power system shutdown. However the concession contracts allow penalties for the unavailability of generation and transmission facilities. Therefore the constant adoption of grounding grid evaluation without the plant shutdown is important. Having these specifications as target this Dissertation presents an embedded system development for voltage and current measurement. Another proposed system component is the software to manage the measuring network and organize the collected information in a database to produce grounding system operation reports. An important aspect of the system is the adoption of wireless network technology to data transfer between each measuring instrument and a web server installed in the power plant operation center. The experimentally obtained results reinforce the system contribution and encourage new developments.
Acesso aberto (Open Access)
Sistema embarcado para monitoramento de harpia (Harpia harpyja)
(Universidade Federal do Pará, 2012-07-04) PANTOJA, Breno Ramos; MANTOVANI, Jose Eduardo; http://lattes.cnpq.br/1714283455902751; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
This Master Thesis consists of an integrated monitoring system for tracking the Harpy Eagle (Harpia harpyja), a species found in Amazon Rainforest, Cerrado and Atlantic Forest. This monitoring system can be divided in three stages: collection, storage and data transmission. The first stage embraces that collection sensors that aim at detecting the presence of birds in the nest, with the support of a camera for video capturing. The second stage executes the data pre-processing and storage. In the third stage, data transmission is performed via the Brazilian System of Ambient Data Collection (SBCDA). This work implemented some of the designed modules, building an incomplete prototype for monitoring. Techniques for embedded systems are also analyzed and the developed detector is evaluated.