Engenharia Elétrica

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http://repositorio.ufes.br/handle/10/17617

Programa de Pós-Graduação em Engenharia Elétrica

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URL do programa: https://engenhariaeletrica.ufes.br/pt-br/pos-graduacao/PPGEE

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A brain-computer interface architecture based on motor mental tasks and music imagery
(Universidade Federal do Espírito Santo, 2013-08-30) Benevides, Alessandro Botti; Bastos Filho, Teodiano Freire; Sarcinelli Filho, Mário; Ferreira, André; Frizera Neto, Anselmo; Conci, Aura; Tierra Criollo, Carlos Julio
This present research proposes a Brain-Computer Interface (BCI) architecture adapted to motor mental tasks and music imagery. For that purpose the statistical properties of the electroencephalographic signal (EEG) were studied, such as its probability distribution function, stationarity, correlation and signal-to-noise ratio (SNR), in order to obtain a minimal empirical and well-founded parameter system for online classification. Stationarity tests were used to estimate the length of the time windows and a minimum length of 1.28 s was obtained. Four algorithms for artifact reduction were tested: threshold analysis, EEG filtering and two Independent Component Analysis (ICA) algorithms. This analysis concluded that the algorithm fastICA is suitable for online artifact removal. The feature extraction used the Power Spectral Density (PSD) and three methods were tested for automatic selection of features in order to have a training step independent of the mental task paradigm, with the best performance obtained with the Kullback-Leibler symmetric divergence method. For the classification, the Linear Discriminant Analysis (LDA) was used and a step of reclassification is suggested. A study of four motor mental tasks and a non-motor related mental task is performed by comparing their periodograms, Event-Related desynchronization/synchronization (ERD/ERS) and SNR. The mental tasks are the imagination of either movement of right and left hands, both feet, rotation of a cube and sound imagery. The EEG SNR was estimated by a comparison with the correlation between the ongoing average and the final ERD/ERS curve, in which we concluded that the mental task of sound imagery would need approximately five times more epochs than the motor-related mental tasks. The ERD/ERS could be measured even for frequencies near 100 Hz, but in absolute amplitudes, the energy variation at 100 Hz was one thousand times smaller than for 10 Hz, which implies that there is a small probability of online detection for BCI applications in high frequency. Thus, most of the usable information for online processing and BCIs corresponds to the α/µ band (low frequency). Finally, the ERD/ERS scalp maps show that the main difference between the sound imagery task and the motor-related mentaltasks is the absence of ERD at the µ band, in the central electrodes, and the presence of ERD at the αband in the temporal and lateral-frontal electrodes, which correspond tothe auditory cortex, the Wernickes area and the Brocas area.
A Control Structure for a Bidirectional DC-AC Converter with Power Quality Support Functions
(Universidade Federal do Espírito Santo, 2022-12-02) Ribeiro, Laila Sindra; Simonetti, Domingos Savio Lyrio; https://orcid.org/0000000159202932; http://lattes.cnpq.br/1107005171102255; https://orcid.org/; http://lattes.cnpq.br/; Encarnacao, Lucas Frizera; https://orcid.org/0000000261627697; http://lattes.cnpq.br/5578918284508758; Reis, Fernando Soares dos; https://orcid.org/; http://lattes.cnpq.br/
abstract
A Estabilidade Transiente de Sistemas Elétricos na Presença de Geradores Síncronos Virtuais: Metodologias de Análise e Controles Adaptativos
(Universidade Federal do Espírito Santo, 2020-11-16) Carletti, Daniel; Encarnacao, Lucas Frizera; https://orcid.org/0000000261627697; http://lattes.cnpq.br/5578918284508758; https://orcid.org/000000027903200X; http://lattes.cnpq.br/; Simonetti, Domingos Savio Lyrio; https://orcid.org/0000000159202932; http://lattes.cnpq.br/1107005171102255; Aredes, Mauricio; https://orcid.org/; http://lattes.cnpq.br/; Medina, Augusto Cesar Rueda; https://orcid.org/0000000242913153; http://lattes.cnpq.br/7397584412509839; Santos, Walbermark Marques dos; https://orcid.org/0000000298716028; http://lattes.cnpq.br/5558697161842579
The dynamic stability assessment of electrical power systems is an activity of utmost importance to guarantee the energy delivery to consumers in a safe and stable way. The study of transient stability, which deals with maintaining the generation plants i
A fairness-focused spectrum assignment algorithm for elastic optical networks
(Universidade Federal do Espírito Santo, 2016-09-27) Tessinari, Rodrigo Stange; Garcia, Anilton Salles; Waldman, Hélio; Martins, Joberto Sérgio Barbosa; Resendo, Leandro Colombi; Segatto, Marcelo Eduardo Vieira; Paiva, Marcia Helena Moreira
In the past few years, Elastic Optical Networking (EON) emerged as the next generation core network technology, intended to surpass Wavelength-Division Multiplexing (WDM) weaknesses and limitations. WDM is the most successful and widely used technology in the backbone of the optical networks. However, in recent years Internet traffic in the core network has been doubling almost every two years, and predictions indicate that it will continue to exhibit exponential growth due to emerging applications such as high-definition and real-time video communications. To keep pace with the always greater demand for bandwidth, EON relies on Optical Orthogonal Frequency Division Multiplexing (OOFDM) and advanced modulation technologies which enhance spectral efficiency and flexibility. OOFDM allows the aggregation of multiple sub-carriers to form super-channels, thus changing the paradigm of the network from fixed-size WDM channels to variable-sized EON channels that can reduce spectrum waste up to 60%. EON presents several other benefits such as high spectral and energy efficiency and flexible bandwidth adaptation over time. Despite all benefits, no technology is perfect, and the added EON efficiency and flexibility comes at the price of increased complexity and new problems, such as spectrum fragmentation and service unfairness. A considerable amount of work has been done on both fragmentation and unfairness problems, introducing a broad range of solutions, which raises the following question: "how to compare existent solutions and how to identify which one is better suited for the required scenario?" In this context, it is presented the first contribution of this Doctoral Thesis, ElasticO++, an Elastic Optical Network Simulation Framework for OMNeT++. ElasticO++ is a framework created to enable testing a whole range of routing, modulation, spectrum assignment, defragmentation algorithms, parameters, and topologies. At present, the proposed framework is the first software available capable of working with fragmentation and defragmentation in dynamic network scenarios. The flexibility offered on the proposed tool allows both academia and industry to develop new algorithms and techniques for Elastic Optical Networks. The second contribution of this Doctoral Thesis is the Zone-Based Spectrum Assignment Algorithm. The proposed algorithm is an attempt to solve the unfairness and fragmentation problems, taking advantage of the spectrum management concept. In this Doctoral Thesis, it is presented two versions of the technique: the static version and the dynamic version. The static version is intended to be used in cases where the information regarding the nature of the network traffic is known beforehand, whereas the dynamic version was developed as a solution in cases in which absolutely no information is known.
A Human-Machine Interface Based on Eye Tracking for Controlling and Monitoring a Smart Home Using the Internet of Things
(Universidade Federal do Espírito Santo, 2019-02-20) Bissoli, Alexandre Luís Cardoso; Encarnação, Lucas Frizera; Bastos Filho, Teodiano Freire; Adams, Kimberly; Krishnan, Sridhar; Villa Parra, Ana Cecilia; Ferreira, André
People with severe disabilities may have difficulties when interacting with their home devices, due to the limitations inherent to their disability. Simple home activities may be even impossible for this group of people. Although many works have been devoted to proposing new assistive technologies to improve the lives of people with disabilities, some studies have found that the abandonment of such technologies is quite high. In this sense, this work presents a new and useful assistive system based on eye tracking for controlling and monitoring a smart home based on internet of things, which was developed following concepts of user-centered design and usability. With this system, a person with severe disabilities was able to control everyday equipment of her residence, such as lamps, television, fan and radio. In addition, her caregiver was able to monitor remotely, by internet, her use of the system in real time. Additionally, the user interface developed here has some functionalities that allowed improving the usability of the system as a whole. The experiments were divided into two steps. In the first step, the assistive system was assembled in an actual home, where tests were conducted with 29 participants without disabilities (group of able-bodied participants). In the second step, the system was tested with online monitoring, for seven days, by a person with severe disability (end-user), in her own home, not only to increase convenience and comfort, but also so that the system could be tested where it would in fact be used. At the end of both steps, all the participants answered the SUS questionnaire, which showed that both the group of able-bodied participants and the person with severe disabilities evaluated the assistive system with a mean of 89.9 and 92.5, respectively.Keywords:Human-Machine Interface (HMI); Human-Computer Interaction (HCI); Smart Home; Eye Tracking; Assistive Technology; Usability Evaluation; User-Centered Design (UCD); Home Automation; Internet of Things (IoT).
A methodology for cloud robotics implementation based on open-source software : from human-robot interaction to autonomous applications
(Universidade Federal do Espírito Santo, 2020-11-26) Mello, Ricardo Carminati de; Neto, Anselmo Frizera; https://orcid.org/0000000206873967; http://lattes.cnpq.br/8928890008799265; https://orcid.org/0000000304204273; http://lattes.cnpq.br/; Ribeiro, Moises Renato Nunes; https://orcid.org/0000000291492391; http://lattes.cnpq.br/1005553714687743; Siqueira, Adriano Almeida Goncalves; https://orcid.org/; http://lattes.cnpq.br/; Garcia, Carlos Andres Cifuentes; https://orcid.org/; http://lattes.cnpq.br/; Diaz, Camilo Arturo Rodriguez; https://orcid.org/0000000196575076; http://lattes.cnpq.br/2410092083336272; Lima, Eduardo Rocon de; http://lattes.cnpq.br/6623746131086816
The advent of the cloud robotics paradigm has the potential to unleash a whole new generation of smart robotic devices by allowing robots to communicate with each other and with remote computing platforms to share experiences, sensor data, and to offload
A novel approach of independent brain-computer interface based on SSVEP
(Universidade Federal do Espírito Santo, 2016-09-01) Tello, Richard Junior Manuel Godinez; Ferreira, André; Müller, Sandra Mara Torres; Bastos Filho, Teodiano Freire; Ciarelli, Patrick Marques; Lima, Eduardo Roncon de; Sá, Antônio Maurício Miranda de
Over the past ten years, Brain Computer Interfaces (BCIs) based on Steady- State Visual Evoked Potentials (SSVEP) have attracted the attention of many researchers due to the promissory results and the high accuracy rates achieved. This type of BCI provides to people with severe neuromotor difficulties the possibility to communicate with the world around them using visual attention modulation to blinking lights at a given frequency. This thesis aiming at developing a new approach of Independent BCI, in which users are not required to perform neuromuscular tasks to select visual targets, a feature that distinguishes it from traditional SSVEP-BCIs. Thus, people with severe motor disabilities as Amyotrophic Lateral Sclerosis (ALS) have a new alternative channel to communicate with the world around them using brain signals. Several contributions were done in this thesis, such as: improvement of the feature extractor called Multivariate Synchronization Index (MSI) for detecting evoked potentials; development of a new method for detecting evoked potentials through correlating multidimensional models (tensors); a first study on the influence of colored stimuli in SSVEPs detection using LEDs; the development of the concept of Compressive sensing applied to SSVEPs; and, finally, the development of a novel independent BCI under an approach named Figure-Ground Perception (FGP)
A novel cascaded multilevel converter topology based on three-phase cells
(Universidade Federal do Espírito Santo, 2021-08-24) Camargo, Renner Sartorio; Encarnacao, Lucas Frizera; https://orcid.org/0000000261627697; http://lattes.cnpq.br/5578918284508758; https://orcid.org/; http://lattes.cnpq.br/; Rolim, Luis Guilherme Barbosa; https://orcid.org/; http://lattes.cnpq.br/; Simonetti, Domingos Savio Lyrio; https://orcid.org/0000000159202932; http://lattes.cnpq.br/1107005171102255; Aredes, Mauricio; https://orcid.org/; http://lattes.cnpq.br/; Nunes, Weder Totola; Santos, Walbermark Marques dos; https://orcid.org/0000000298716028; http://lattes.cnpq.br/5558697161842579; Peña, Emilio José Bueno
Due to the structural characteristics of modern electrical grids, composed mainly of an energy matrix that is very diverse and sparse, and by electrical loads that demand high power levels, maintaining electrical energy within the quality standards define
A novel stimulation paradigm for a brain-computer interface based on SSVEP
(Universidade Federal do Espírito Santo, 2015-11-30) Atencio, Anibal Cotrina; Ferreira, André; Bastos Filho,Teodiano Freire; Frizera Neto, Anselmo; Sarcinelli Filho, Mario; Krohling, Renato Antônio; Sá, Antonio Mauricio Ferreira Leite Miranda de
Brain-computer interfaces (BCIs) are systems that provide a direct connection between users’ brain signals and a computer, generating an alternative channel of communication that does not involve the traditional way as muscles and nerves. They help to restore or replace useful functions of people with paralysis. For instance, BCI systems based on SSVEP (SSVEP-BCI) present a set of stimuli flickering at different frequencies to the users, detect which stimulus is being gazed and associate this information to commands that can be used to control a robotic wheelchair, an exoskeleton, or a speller. Nowadays, SSVEP-BCIs are being widely used due to the high SNR of their response that is achieved when the target stimulus is brought to the center of the user’s field of view. Paradoxically, it is their main disadvantage because bringing a stimulus to the center of the field of view demands muscular activity making them not suitably for paralyzed people who cannot control their head, neck and/or eyeball movements for redirecting their gaze. In optical systems, the range of distance near the point of focus where objects are perceived sharp is referred as Depth-of-field; objects outside this region are defocused and blurred. The mechanism of the visual system that adjusts the eye focal length for focusing does not demand neck, head and/or eyeball movements. Furthermore, ophthalmology studies state that the amplitude and the latency of visual evoked potentials are affected by defocusing. In this context, this Thesis proposes a novel SSVEP-BCI paradigm, in which two stimuli are presented together in the center of the user’s field of view but at different distances from him, ensuring that if one stimulus is focused on, the other one is non-focused, and vice versa; with the aim of providing an alternative way of sending commands through a stimuli selection by a focusing mechanism. In this sense, first, a model of VEP generation for two stimuli is introduced and the hypothesis that distinguishable SSVEP can be elicited by the focused stimulus, regardless of the non-focused stimulus is also present, is tested by employing the SFT-based ORD. Next, a demodulation method based in LPF and HPF is proposed for the case in that two stimuli are present in the field of view; and spatial-temporal retinal response for flickering stimuli is described by using PSF and NPSF functions. Finally, CCA, PSDA, LASSO with EEG signals re-referenced at Pz and CAR are employed to detect the SSVEP pattern. Accuracy rate, Kappa coefficient, AUC, and ITR are used to evaluate the detection performance. As a result of the hypothesis test, the absence of evoked potentials due to a focused stimulus, when a non-focused stimulus is also present was rejected in most of the cases. In SSVEP detection experiments, an average accuracy rate of 0.93 was achieved for a time window of 7s and for eight healthy subjects who were asked to focus on just one stimulus at a time.
A rede de média tensão como meio de transporte de dados em redes smart grid
(Universidade Federal do Espírito Santo, 2015-12-11) Castor, Leonardo Ribas Martins; Silva, Jair Adriano Lima; Segatto, Marcelo Eduardo Vieira; Garcia, Anilton Salles; Souza, Flávio Rabello de
The main purpose of any company is to increase its production with reduced operating costs and in the Oil & Gas industry is not different. In this scenario industrial automation plays a key role, maximizing operational safety and production efficiency. The use of human resources in order to operating, monitoring and controlling productionś processes is intense on this field, which is, yet, a serious drawback for this kind of company. Systems communications as part of the productionś automation contribute for reducing the operative expenditure and at same time provide efficient and reliable data traffic. The Oil & Gas industry has used fibre optics and wireless communications systems as last mile network solutions. However, these networks are implemented with high costs and at long time. More recently, the technology of data transmission over power line grid, called PLC, has becomes economically and technically a more interesting solution related to others technologies. As the onshore oil wells are already covered by the medium voltage power line grid, the reduced installationś costs for a PLC data network makes the project mre attractive. Additionally, the new PLC system use modern techniques, such as, adaptative coding and modulation, multiple access protocols, QoS, etc, for ensuring robustness, better use of signal power and greater privacy of data transmitted. In contrast, its performance depends on the communication channel condition based on transmission multipath, frequency selectivity, impulsive noise, RF interference, and others. This work was developed under a real scenario of Smart Grid conception. Through a three-phase medium voltage grid, supervisory, control and video surveillance information in oil production process have been transported to the remote operation center located at SM-8, São Mateus. It was obtained upstream and downstream speeds of 60 Mbps approximately in the physical layer through a multipath PLC channel with 322 m long without repeater. In a multipath stretch of 2 km long, a 3 Mbps ethernet traffic composed by automation data and high-definition images, was transported in a real-time frame to their servers without errors.
A socially assistive robot as a therapeutic tool for applied behavior analysis therapy in children with autism spectrum disorder through dynamically modulated serious games
(Universidade Federal do Espírito Santo, 2024-10-07) Freitas, Éberte Valter da Silva; Bastos Filho, Teodiano Freire; https://orcid.org/0000-0002-1185-2773; Caldeira, Eliete Maria; Cuadros, Marco Antonio de Souza Leite; Valadão, Carlos Torturella; Vasquez, Luiz Fernando Guerrero
This work presents the programming/adaptation of the Socially Assistive Robot (SAR) called Mobile Autonomous Robot for Interaction with Autistics and Trisomy 21 (MARIA T21) to be able to carry out interventions, according to the Applied Behavior Analysis (ABA) therapy, applied to Children with Autism Spectrum Disorder (ASD), Serious Games (SGs), which are projected by MARIA T21, with difficulty modulation dynamics, are used as part of this therapy thus creating a motivating and facilitating effect for children and therapists. The SGs were developed in Unity 3D, using C Sharp language (C#), and modulated according to the child’s performance, eye attention level, and user’s facial emotion, being integrated into the robot through the Robot Operating System (ROS). The child-Robot Interaction (CRI) protocol followed in this research was carried out in a child’s psychotherapy room at the APAE (Association of Parents and Friends of Excepcional People for the acronym in Portuguese) of Vitoria in Espirito Santo state (Brazil), which was instrumented with four video cameras and supervised by a group of researchers. The sample consisted of 18 children with a conclusive diagnosis of ASD, 3 girls and 15 boys, aged 5 to 9 years and presence of stereotyped movements of eyes and/or hands and/or feet. The experiments were separated into three modules for which SGs or specific therapeutic dynamics were applied, namely: Cognitive Module, Physical Module and Functional Module. The first one brings together the games and dynamics applied by MARIA T21 focused on the development and improvement of cognitive learning skills, whereas the physical module brings SGs for motor evaluation and correction, that can be used for physical and postural strengthening by a physiotherapist. Finally, the functional module has applications of SGs and Occupational Therapy dynamics in order to work on the so-called Activities of Daily Living (ADLs) and encourage autonomy in those assisted. In addition to the data recorded by MARIA T21, two evaluation scales– Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) and System Usability Scale (SUS)– were applied for each module, and another for the degree of acceptance of the robot in therapy by the child. The results obtained so far enable the use MARIA T21 as an ABA therapeutic tool. In addition, the SGs are capable of dynamically modulating their difficulty, providing greater user adherence and continued attention in the optimal learning zone of the ABA bibliography while carrying out the activities. The technology embedded in the robot has also enabled the identification and quantification of characteristics and parameters, such as the presence and recurrence of stereotypies and postural dysregulations, placing the robot as an innovative and promising tool to assist health professionals in the early diagnosis, conduction and follow-up of therapies.
Adaptação dos modelos de Markov para um sistema de segmentação e classificação de sinais de eletrocardiograma
(Universidade Federal do Espírito Santo, 2006-04-03) Müller, Sandra Mara Torres; Andreão, Rodrigo Varejão; Bastos Filho, Teodiano Freire; Sarcinelli Filho, Mário; Resende Junior, Fernando Gil Vianna; Salles, Evandro Ottoni Teatini
In this work three incremental adaptation methods for the hidden Markov models (HMM) are studied and implemented, which are based on the Expectation-Maximization (EM), Segmental k-Means and Maximum a Posteriori (MAP) algorithms. These methods, already used in the speech recognition field, are applied here in the electrocardiogram (ECG) segmentation problem. For that, it was used an ECG analysis system able to segment and classify cardiac diseases, like premature ventricular contraction (PVC) and ischemia. The use of these methods allow us to adjust the models to the signal fluctuations commonly met during ambulatory recording. The methods can also be implemented for other kinds of biomedical signals, like electroencephalogram (EEG).
Adaptive x-ray tomography image reconstruction
(Universidade Federal do Espírito Santo, 2019-08-08) Wirtti, Tiago Tadeu; Salles, Evandro Ottoni Teatini; https://orcid.org/0000000282873045; http://lattes.cnpq.br/5893731382102675; https://orcid.org/ 0000-0003-0731-6326 ; http://lattes.cnpq.br/3414259707581590; Filho, Mario Sarcinelli; https://orcid.org/0000000276968996; http://lattes.cnpq.br/3459331011913021; Andreao, Rodrigo Varejao; https://orcid.org/0000000268005700; http://lattes.cnpq.br/5589662366089944; Pinto, Luiz Alberto; https://orcid.org/; http://lattes.cnpq.br/; Kim, Hae Yong
In X-ray tomography image reconstruction, one of the most successful approaches involves a statistical modeling with l2 norm function for fidelity regularized by a functional with lp norm, 1 < p < 2, with p ∈ R. Among them stands out, for its results and computational performance, a technique that reconstructs an image by alternating minimization for (i) solving the l2 norm fidelity term by Simultaneous Algebraic Reconstruction Technique (SART) and (ii) constraining the regularization term, defined by a Discrete Gradient Transform (DGT) sparse transformation, using Total Variation (TV) minimization. This work proposes an improvement to the reconstruction process by adding a Bilateral Edge preserving (BEP) regularization term to the objective function, resulting in a three-step method. BEP is a noise reduction framework and has the purpose of adaptively eliminating noise in the initial phase of reconstruction process. BEP improves optimization of the f idelity term and, as a consequence, improves the result of DGT minimization by total variation. Regular dosage experiments shown favorable results compared to classical methods, such as Filtred Backprojection (FBP), and more modern ones, such as l2 norm optimization by using SART, and the l2 norm SART solution regularized by l1 norm TV optimization of DGT (SART+DGT), especially with the Structural Similarity Index Measurement (SSIM) metric. Although not so prominent in the case of regular dosing reconstruction, Peak Signal-to-noise Ratio (PSNR) results are consistent with those of SSIM. For low dosage, the quality of the reconstruction worsens for all methods, but is markedly lower for the FBP and SART methods. In this context of limited number of projections (low dosage), the reconstructions with the method here proposed presents better defined edges, in addition to better contrast and less artifacts in surfaces of regular intensity (low intensity variation). These results are generally obtained with a smaller number of steps compared to the other iterative methods implemented in this Thesis. However, this behavior (of the proposed method) depends on the parameterization of the lp norm, 1 ≤ p ≤ 2, used in the BEP stage. It is experimentally shown that by varying the norm during the reconstruction process it is possible to keep the proposed method stable over a sufficiently large number of iteractions. It is also graphically shown that the method converge, meaning that the SSIM and PSNR metrics can be continuously improved by a sufficiently large number of iteractions. For reconstructions with a limited number of projections (low-dose reconstruction), the proposed method can achieve higher PSNR and SSIM results because it can better control the noise in the initial processing phase.
Adequação ao requisito cintilação em sistemas de comunicação via luz visível mediante uso de sinais OFDM com envoltória constante
(Universidade Federal do Espírito Santo, 2018-09-21) Neves, José Luís Costa; Segatto, Marcelo Eduardo Vieira; Silva, Jair Adriano Lima; Nunes, Reginaldo Barbosa; Pereira, Esequiel da Veiga; Pontes, Maria José
The scarcity of electromagnetic spectrum has been a problem in the development of new wireless applications. To solve this problem, visible light communication has emerged as a promising and complementary technology to radiofrequency due to its advantages such as green technology, unlicensed spectrum, low power consumption, high privacy protection and resistance to electromagnetic interference . Allied to this, because it is a technology that uses light emitting diodes for data transmission, also guaranteeing the lighting function, it allows its use in di erent types of environments. Orthogonal frequency division multiplexing (OFDM) in visible light communication systems has been attractive because of its ability to combat intersymbol interference and ensuring high data rates. However, OFDM signals have large amplitude uctuations, resulting in high peak-to-average power ratio (PAPR) and therefore can degrade the quality of the illumination due to Flicker light. Flickering light is harmful to vision and causes eye fatigue, seizures, headache, malaise, and other problems. The present work presents a simulation and experimental study that evaluates the performance of the OFDM transmission technique that transmits signals with constant envelope (CE-OFDM) in a communication system via visible light, by means of the adequacy of the Flickering requirements. The CE-OFDM system is based on the phase modulation of an electric carrier and reduces the PAPR parameter to 3 dB. The results obtained in the line-of-sight channel using a bandwidth of 5 MHz showed that, by adapting the icker requirements and considering the mapping levels 4, 16 and 64-QAM, the CE-OFDM system presents a upper performance than those presented by the conventional OFDM and ACO-OFDM systems. The results also showed that, in the presence of non-linearities introduced by the LED, the CE-OFDM system presents greater robustness.
Admittance control of a robotic knee orthosis based on motion intention through sEMG of trunk muscles
(Universidade Federal do Espírito Santo, 2017-12-04) Parra, Ana Cecilia Villa; Frizera Neto, Anselmo; Bastos Filho, Teodiano Freire; Ferreira, Andre; Caldeira, Eliete Maria de Oliveira; Rocon, Eduardo; Bó, Antonio Padilha Lanari
The population that requires devices for motion improvement has increased considerably, due to aging and neurological impairments. Robotic devices, such as robotic orthosis, have greatly advanced with the objective of improving both the mobility and quality of life of people. Clinical researches remark that these devices, working in constant interaction with the neuromuscular and skeletal human system, improves functional compensation and rehabilitation. Hence, the users become an active part of the training/rehabilitation, facilitating their involvement and improving their neural plasticity. For this purpose, control approaches based on motion intention have been presented as a novel control framework for robotic devices. This work presents the development of a novel robotic knee exoskeleton controlled by motion intention based on sEMG, which uses admittance modulation to assist people with reduced mobility and improve their locomotion. For recognition of the lower-limb motion intention, sEMG signals from trunk are used, which implies a new approach to control robotic assistive devices. The control system developed here includes a stage for human-motion intention recognition (HMIR) system, which is based on techniques to classify motion classes related to knee joint. The motion classes that are taken into account are: stand-up, sit-down, knee flexionextension, walking, rest in stand-up position and rest sit-down position. For translation of the users intention to a desired state for the robotic knee exoskeleton, the system includes a finite state machine, in addition to admittance, velocity and trajectory controllers, which has also the function of stopping the movement according to the users intention. This work also proposes a method for on-line knee impedance modulation, which generates variable gains through the gait cycle for stance control during gait. The proposed HMIR system showed, in off-line analysis, an accuracy between 76% to 83% to recognize motion intention of lower-limb muscles, and 71% to 77% for trunk. Experimental on-line results of the controller showed that the admittance controller proposed here offers knee support in 50% of the gait cycle, and assists correctly the motion classes. A positive effect of the controller on users regarding safety during gait was also found, with a score of 4 in a scale of 5. Thus the robotic knee exoskeleton introduced here is an alternative method to empower knee movements using motion intention based on sEMG signals from lower limb and trunk muscles.
Algoritmo de calibração de magnetômetros triaxiais utilizando ajuste de quádrica por distância algébrica
(Universidade Federal do Espírito Santo, 2017-08-22) Mucciaccia, Sérgio Silva; Salles, Evandro Ottoni Teatini; Frizera Neto, Anselmo; Ciarelli, Patrick Marques; Nogueira, Samuel Lourenço
The measurements obtained from magnetometers are sensitive to disturbances and errors, requiring a calibration method that can considerably improve accuracy. The ellipsoid fitting is one of the most widely used methods for magnetometer calibration, but most algorithms use iterative methods, causing runtime and convergence problems. As an alternative, a direct algorithm based on the method of least squares using the algebraic distance metric is proposed. This present work presents an algorithm of calibration of magnetometers and its use in a system of calibration and fusion of data of magnetometers, accelerometers and gyroscopes based on a Kalman filter forming an inertial sensor able to obtain its orientation in the space. Computational simulations and tests with real data show that the calibration algorithm eliminates almost all the linear errors while performing much faster than traditional algorithms. Measurements of a magnetometer calibrated with the proposed algorithm are used in conjunction with measurements from accelerometers and gyroscopes to form an inertial measurement unit (IMU) using a simple Kalman filter. The complete system worked as expected and the test results indicate that the magnetometer calibration algorithm is suitable for use in an IMU being more than ten times faster than traditional algorithms and presenting similar accuracy
Algoritmos Evolutivos Aplicados em Projetos de Redes Ópticas Passivas
(Universidade Federal do Espírito Santo, 2019-08-23) Silva, David Moscon Inacio; Rocha, Helder Roberto de Oliveira; https://orcid.org/000000016215664X; http://lattes.cnpq.br/8801325729735529; https://orcid.org/; http://lattes.cnpq.br/; Moraes, Renato Elias Nunes de; https://orcid.org/; http://lattes.cnpq.br/; Nunes, Reginaldo Barbosa; https://orcid.org/; http://lattes.cnpq.br/
tba
Alocação de Recursos de uma Rede Óptica Passiva BS-OFDMA-PON usando Otimização Multiobjetivo
(Universidade Federal do Espírito Santo, 2020-12-18) Flores, Jardel Terci; Rocha, Helder Roberto de Oliveira; https://orcid.org/000000016215664X; http://lattes.cnpq.br/8801325729735529; https://orcid.org/; http://lattes.cnpq.br/; Coura, Daniel Jose Custodio; https://orcid.org/0000000221347981; http://lattes.cnpq.br/5570995348839001; Nunes, Reginaldo Barbosa; https://orcid.org/; http://lattes.cnpq.br/
With the growing demand for Internet traffic by users and the increased need for transmission rate by applications, it is necessary to use bandwidth efficiently and economically in optical networks, which plays an important role in improving service deliv
Alocação de Recursos em Redes de Sensores IoT Híbrida ZigBee e LoRa
(Universidade Federal do Espírito Santo, 2020-12-21) Santos, Willian Garcia Viega dos; Segatto, Marcelo Eduardo Vieira; https://orcid.org/000000034083992X; http://lattes.cnpq.br/2379169013108798; https://orcid.org/; http://lattes.cnpq.br/; Munaro, Celso Jose; https://orcid.org/0000000222977395; http://lattes.cnpq.br/5929530967371970; Lima, Fabio de Oliveira; https://orcid.org/; http://lattes.cnpq.br/
With the growth in the number of devices on IoT networks, the requirements for communication reliability and efficient use of energy are increasing. In this work, a hybrid network topology for IoT sensors is proposed, using the mesh and star topologies. T
Alocação de Recursos em um fronthaul Óptico com functional split Recomendado para o 5G
(Universidade Federal do Espírito Santo, 2020-06-30) Amaral, Murilo Porto; Silva, Jair Adriano Lima; https://orcid.org/000000032567184X; http://lattes.cnpq.br/3099010533644898; https://orcid.org/; http://lattes.cnpq.br/; Garcia, Anilton Salles; https://orcid.org/; http://lattes.cnpq.br/1029501009628001; Dalarmelina, Carlos Alberto; https://orcid.org/; http://lattes.cnpq.br/
It is presented in this dissertation the application of functional split technic applied in an access network section model, tested on a dynamic optical fronthaul simulator developed fot the 5G technology. The adjustment made by selecting a level of the f

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