Xisto Lucas Travassos

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Verified

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• PhD
• Associate Professor at Universidade Federal de Santa Catarina

With the advances of Radio Access Networks, the Open RAN introduced the concept of virtualization and openness to the mobile network elements. These characteristics allow multi-vendor implementations in commercial out-of-shelf hardware with open radio interfaces beyond flexibility and scalability, permitting bringing the data processing to the netw...

COVID-19, an infectious disease caused by the virus SARS-CoV-2, has become a global pandemic and has been classified as a Public Health Emergency of International Concern. Considering vaccines as an effective action to shorten viral transmission and to reduce mortality, stakeholders have worked together to develop vaccines, which played a vital rol...

Objective: This study aims to develop and empirically test a derivation of the Technology Acceptance Model (TAM) on the acceptance of electric vehicles (EV). Theoretical Approach/Method: The analysis was based on an original theoretical model adapted from the TAM, a theory based on information systems that models how users start to accept and use a...

Digital transformation is increasingly essential for enhancing efficiency and data security. This study explores the impacts that Artificial Intelligence (AI) may have on the control of public procurement under the New Bidding Law. A systematic review of the literature on AI and public agencies was conducted. The findings indicate that the use of A...

COVID-19, an infectious disease caused by the virus SARS-CoV-2, has become a global pandemic and has been classified as a Public Health Emergency of International Concern. Considering vaccines as an effective action to shorten viral transmission and to reduce mortality, stakeholders have worked together to develop vaccines, which played a vital rol...

Electronic Lab Notebooks (ELNs) have seen a significant rise in research laboratories. However, realizing the benefits of ELNs requires the active participation of employees within an organization. This study aims to identify the factors contributing to resistance towards adopting an ELN, specifically eLabFTW. A semistructured questionnaire, valida...

The milk food production chain is present throughout the country and has undergone many changes over time. It is extremely important to know and understand the current scenario of milk production, identifying the potential, limits and needs of this sector. The aim of this work is to research the family milk production chain in the state of Rio de J...

The automotive industry has always relied on innovation to drive its growth, with Ford Motor Company at the forefront of this transformation. Today, digital transformation is a key focus, with technologies such as AI, big data, and blockchain being used to improve personalized user experiences, develop connected and autonomous vehicles, optimize su...

The automotive industry has always relied on innovation to drive its growth, with Ford Motor Company at the forefront of this transformation. Today, digital transformation is a key focus, with technologies such as AI, big data, and blockchain being used to improve personalized user experiences, develop connected and autonomous vehicles, optimize su...

The automotive industry has always relied on innovation to drive its growth, with Ford Motor Company at the forefront of this transformation. Today, digital transformation is a key focus, with technologies such as AI, big data, and blockchain being used to improve personalized user experiences, develop connected and autonomous vehicles, optimize su...

The upholding of a Quality Management System (QMS) during situations requiring emergency changes is challenging for organizations. Change management may help ensure these changes are carried out in ways that, while achieving their objectives, promote the appropriate improvements in each context. In a QMS, according to ISO IEC 17025:2017, the change...

The pandemic caused by the SARS-CoV-2 virus, a new strain identified in humans and the etiologic agent of Covid-19 represents a health threat to humanity. There are currently seven members of this viral family, known to infect humans, with the potential to cause severe respiratory diseases. In order to meet this demand, the development of an effect...

Most of the electricity generated in Brazil still comes from hydroelectric plants. In 2021, the country reached a critical hydrological scenario due to low capacities in the reservoirs. Although the installed wind power capacity in Brazil has expanded considerably in recent years, wind generation in the country is limited to the onshore type. This...

The Paris Agreement was signed to reduce greenhouse gas emissions, and Brazil is committed to increasing renewable energy participation in the electrical matrix. This study aims to evaluate how wind energy fulfils the goals determined in the agreement. Through a systematic literature review, 10 relevant studies were identified and together with the...

Microwave technology has many current applications. It is very useful for food processing, including domestic cooking and warming-up and industrial heating and drying. It heats faster than conventional applications; however, in most cases result in non-uniform temperature distribution. Adequate cavity and equipment designs can reduce the impact of...

This paper presents proposals for technological solutions to previously detect violence among passengers of a shared autonomous transport mode. By analyzing the Design Science Research method and the conjectural behavior of the population, the problem contextualization about the safety of public transport can be determined in terms of violence. So,...

The use of renewable sources for electricity generation has as main benefits the preservation of natural resources, security in the distribution of electricity and the reduction of greenhouse gas emissions. Research has shown that the participation of wind in the Brazilian electrical matrix has increased considerably in recent years, despite the ex...

This study aimed to review the production of patent documents related to assistive technology on adapted vehicles for people with disabilities. The technological prospection was carried out through a search on the Espacenet database, resulting in 277 patents whose data we organized into charts. The results show that the total number of patents file...

This paper presents a radiofrequency electromagnetic field exposure assessment carried out in an observatory open for general public, where there are multiple radio and television transmitters in the surrounding area. An uncertainty evaluation is presented, considering that the main broadcast stations reduced their transmitted power to comply with...

RF-EMF exposure assessment carried out in an observatory open for general public visits, where there are multiple RF sources in the surrounding area. Fields at some points of interest have exceeded the ICNIRP exposure limits for the general public and, to comply with normative limits, relevant stations reduced their radiated power. Nevertheless, th...

The present paper aims to model some of the lightning strikes effects on a composite material modeled through numerical simulation. The simulation is based on the finite-difference time-domain (FDTD) method which allows the analysis of the electromagnetic and thermal effects related to the problem. The thermal distribution is evaluated based on res...

In this paper, UHF RFID tag antennas (902-928cMHz) are evaluated in order to find the structures that provide both easier impedance matching to a specific circuit (microchip) and acceptable performance for coffee sacks monitoring in a supply chain. Folded dipole, meander-line, patch and slot antennas surrounded by a box having the same properties o...

This paper presents a radiofrequency electromagnetic field exposure assessment carried out in an observatory open for general public, where there are multiple radio and television transmitters in the surrounding area. An uncertainty evaluation is presented, considering that the main broadcast stations reduced their transmitted power to comply with...

Composite materials have diverse engineering applications including the automotive, energy and aerospace industries. In manufacturing aircraft structures, the material is expected to endure atmospheric discharges. The present paper aims to model some of the effects of lightning strikes on a composite materials modeled through numerical simulation....

The present paper aims to model some of the effects of lightning strikes on a composite material modeled through numerical simulation. The simulation is based on the finite-difference time-domain (FDTD) method which allows the analysis of the electromagnetic and thermal effects related to the problem. The thermal distribution is evaluated based on...

An antenna can be considered as a two-port transducer system characterized by a transfer function that can be frequency-dependent and may have a non-linear phase response. The performance of this complex device is critical for time or frequency-domain ground penetrating radar (GPR) systems. We recently published a framework for GPR antenna design a...

Na última década, a indústria mundial tem passado por rápidas e profundas mudanças induzidas pela introdução de novas tecnologias digitais. Essa mudança de paradigma é denominada quarta revolução industrial ou “Indústria 4.0”. Os impactos dessas mudanças nas relações de trabalho e no sistema de educação são inevitáveis. O 1º Workshop Internacional:...

Atualmente são ressaltadas as vantagens da cooperação entre organizações para alavancar o desenvolvimento de setores econômicos. Esse contexto vêm sendo explicitado cada vez mais, dado a acontecimentos causados pela rapidez das mudanças societárias, derivadas muitas delas da evolução das tecnologias da informação, como a Internet. No Brasil, existe...

Resumo: Este estudo de caso trata dos fatores de sucesso e melhores práticas na gestão de projetos em desenvolvimento de produtos por uma montadora de veículos com unidades no Brasil. Seu objetivo é identificar o grau de aderência das práticas da montadora às melhores práticas em gestão de projetos a partir de quatro dimensões-chave-estrutura organ...

Ground Penetrating Radar is a multidisciplinary Nondestructive Evaluation technique that requires knowledge of electromagnetic wave propagation, material properties and antenna theory. Under some circumstances this tool may require auxiliary algorithms to improve the interpretation of the collected data. Detection, location and definition of target...

—Ground Penetrating Radar is a complex nondestructive evaluation technique where the antenna is the most critical part. The antenna is responsible for transmission and reception of waves at the proper level and frequencies defined in the GPR system specifications. Important GPR features such as resolution and penetration depth depend on its charact...

This article presents a parameters investigation of microstrip antenna substrate produced by niobium pentoxide (Nb2O5) powder metallurgy. Theoretical studies and experimental measurements of the substrate electrical properties were performed. The niobium pentoxide compaction pressure and the sintering temperature were studied in order to determine...

This paper presents RF-EMF exposure assessment carried out in an observatory recently opened for general public visitation, where there are many RF sources in the surrounding area. Some points of interest have exceeded the ICNIRP exposure limits for the general public and, to accomplish with normative limits in the far field region, relevant statio...

Este artigo tem como objetivo apresentar uma análise realizada sobre o nível de implantação do processo de autoavaliação nas faculdades privadas de Salvador na visão dos coordenadores da CPA. Para tanto, realizou-se uma pesquisa com 14 faculdades privadas de Salvador, utilizando como instrumento de coleta de dados, o questionário, com questões mist...

Among the intended and unintended interferences, some sources can be physically identified such as those produced by power lines (TL). To mitigate the TL frequency spectrum, this work aims to identify the bandwidth that best represents the spectral responses of the insulators using statistical signal processing approaches. The normality and correla...

In the pharmaceutical industry, value is being destroyed through longer product development times. Given that patent lives are (normally) fixed at 20 years, the double hit of increasing time to market is evident – higher R&D costs and less time at market before generic competitors are able to be released into the marketplace. The Policy implication...

In the pharmaceutical industry, value is being destroyed through longer product development times. Given that patent lives are (normally) fixed at 20 years, the double hit of increasing time to market is evident – higher R&D costs and less time at market before generic competitors are able to be released into the marketplace. The Policy implication...

This paper presents a prediction algorithm for features detection in Ground Penetrating Radar (GPR) based surveys. Based on signal processing and soft-computing techniques, the coupled use of principal-component analysis and neural networks enables a definition of an efficient method for analyzing GPR electromagnetic data. To guarantee a low error...

The purpose of this study is to describe a methodology to assess the financial viability of radio frequency identification (RFID) applications and the main contributions of this technology. The impact of RFID technology on supply chain processes was assessed using an Internal Rate of Return analysis. An extensive, six-month discussion and refinemen...

This paper presents a methodology for the integration of RFID technology into microcomputer assembly companies. Such a technology enables inventory control, tracking of parts/products and customer satisfaction. The methodology was developed to identify and evaluate the production process in an assembly company and to apply the process FMEA to evalu...

This paper discusses research activities for innovative industry in the state of Bahia under the theme of Environmental Management through the course of professional master. We describe several lines of research initiated and influenced by demand from industry in Bahia, especially in the role of the student graduate professional master's program in...

Este artigo tem como objetivo fazer uma proposta de aplicacao da tecnologia RFID – Radio Frequency Identification (Identificacao por Radiofrequencia), em empresas montadoras de microcomputadores, para o controle de estoque e rastreabilidade de insumos/produtos. Para justificar a vantagem da aplicacao da tecnologia RFID, utilizou-se a Analise dos Mo...

The market of logistic operators in the segment of parcel delivery in Brazil has grown considerably in the last few years. This growth is caused mainly by e-commerce transactions. Companies that excel in this business offer services that enable traceability of objects and near real-time availability of information to customers. This research aims t...

This paper aims to analyze the frequency of occurrence of different forms of communication in nonspeaking children during activities with digital games. The participants in this study were three children with multiple disabilities, whose limitations were due to cerebral palsy. All the children had severe oral communication disabilities. Three digit...

Na perspectiva da Tecnologia Assistiva e de sua aplicação no contexto da Comunicação Alternativa, os jogos digitais podem ser produzidos e aplicados em atividades lúdicas junto às crianças com transtorno severo da fala com o intuito de ampliar a comunicação e, consequentemente, contribuir para a promoção do desenvolvimento infantil. Diante desses p...

This paper describes some efforts to design more efficient analysis for the GPR raw-data interpretation. Such analysis requires algorithms by which problems having complex scattering properties can be solved as accurately and as quickly as possible. This specification is difficult to achieve when dealing with iteratively solved algorithms characte...

Ground Penetrating Radar systems have been successfully used to access concrete structures conditions. Moreover, inclusions in concrete can be discriminated by simple models based on traces obtained by GPR. In this work, concrete blocks with different inclusions were probed in controlled conditions. Some features were extracted from Ascans of this...

Industrial organizations have increasingly sought to optimize the resources needed for the manufacture of its products from the competition, in order to maintain their profit margins. The search for balance of resources and balanced distribution of tasks in various types of industrial environments is called balancing. When adjustments are made and...

This paper presents a numerical procedure to calculate the time-domain response of thin-wire antennas over Debye media. The method is based in an expansion of the electric-field integral-equation in the time-domain (EFIE-TD), which accounts for the Debye media by using a reflection-coefficient approach. Resulting extended integral equation is subse...

To increase car passenger safety, the Brazilian National Traffic Council (CONTRAN) released Resolution 221, which defines the maximum passenger and driver biomechanical criteria in the event of a vehicle frontal impact. The vehicle maximum allowed biomechanical injury criteria will be enforced from January 2012 for new vehicles and in January 2014...

This paper presents a numerical procedure to calculate the time-domain response of thin-wire antennas over Debye media. The method is based in an expansion of the electricfield integral-equation in the time-domain (EFIETD), which accounts for the Debye media by using a reflection-coefficient approach. Resulting extended integral equation is subsequ...

Este capítulo apresenta uma metodologia para modelagem computacional do controle não destrutivo eletromagnético para estruturas de concreto para aprimoramento dos componentes do sistema e da detecção de falhas e inclusões. O concreto é o principal material de construção de grandes estruturas como pontes, estradas e centrais elétricas. Normalmente t...

This paper presents several applications of multiobjective optimization to antenna design, emphasizing the main general steps in this process. Specifications of antennas usually involve many conflicting objectives related to directivity, impedance matching, cross-polarization, and frequency range. These requirements induce multiobjective problems,...

This paper presents optimization problem formulations to design meander-line antennas for passive UHF radio frequency identification tags based on given specifications of input impedance, frequency range, and geometric constraints. In this application, there is a need for directive transponders to select properly the target tag, which in turn must...

The current work studies the relevance of features in time- and frequency-domain given a scattered Ground Penetrating Radar (GPR) wave. This wave is used to identify inclusions, such as reinforcement bars and fissures, in concrete structures. The right choice of features is fundamental to the design of intelligent machines to support the detection,...

This paper presents several applications of multiobjective optimization to antenna design, emphasizing the main general steps in this process. Specifications of antennas usually involve many conflicting objectives, related to directivity, impedance matching, cross-polarization and frequency range. These requirements induces multiobjective problems,...

This paper presents optimization problem formulations to design meander-line antennas for passive radio frequency identification tags based on given specifications of input impedance, frequency range and geometric constraints. In this application, there is a need for directive transponders to select properly the target tag, which must be ideally is...

Abstract—his paper studies the relevance of features in time-and frequency-domain given a scattered Ground Penetrating Radar (GPR) wave. This wave is used to identify inclusions, such as reinforment bars and fissures, in concrete structures. The right choice of features is fundamental to the design of intelligent machines to support the detection,...

This paper applies the minimum gradient method (MGM) to denoise signals in engineering problems. The MGM is a novel technique based on the complexity control, which defines the learning as a bi-objective problem in such a way to find the best trade-off between the empirical risk and the machine complexity. A neural network trained with this method...

In order to maximize the performance of subsurface radar investigations, there exists a vast range of algorithms that can be applied to the data obtained to find the target's location and reflectivity. Minimizing the data computing time becomes the primary issue in choosing one algorithm over another. In this work, three imaging methods are used to...

This paper applies artificial neural networks (ANNs) trained with a multiobjective algorithm to preprocess the ground penetrating radar data obtained from a finite-difference time-domain (FDTD) model. This preprocessing aims at improving the target's reflected wave signal-to-noise ratio (SNR). Once trained, the NN behaves as an adaptive filter whic...

This paper aims at detecting and characterizing inclusions in concrete structures by inverting ground-penetrating radar (GPR) data. First, the signal is preprocessed using the principal component analysis (PCA) and then used to train an artificial neural network (ANN). The GPR data consists of 1200 time steps. Using PCA, the data can be compressed...

This paper investigates the characterization of inclusions in concrete structures, including the number of inclusions, their geometries, and electromagnetic properties. To solve this problem, a two phase algorithm that combines matched-filter-based reverse-time (MFBRT) migration algorithm with the particle swarm optimization (PSO) is employed. The...

Recent developments in ground-penetrating radar (GPR) models have brought about complex electromagnetic fields due to the fine variations of structures. Therefore, it has become necessary to use more accurate analysis including environmental characteristics, antennas, and interpretation of the raw data in three-dimensional space. Such analyses requ...

Concrete is the most common building material and accounts for a large part of the systems that are necessary for a country to operate smoothly including buildings, roads, and bridges. Nondestructive testing is one of the techniques that can be used to assess the structural condition. It provides nonperceptible information that conventional techniq...

In order to resolve closely spaced targets in a planar surface normal to the beam, the antenna used in the radar assessment of concrete structures should have a narrow beam width which means a higher directivity. To optimize the field pattern of an antenna it was implemented a procedure that unifies multi-objective genetic algorithms (MGA) and a mo...

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Antennas are one of the most critical parts in ground penetrating radar (GPR) systems. They substantially determine the quality of the obtained GPR raw data [1]. For work on concrete two main types of antenna are used, generally described as either dipoles that operate in close proximity to the material to be surveyed or TEM horns that operate at l...

The non-destructive inspection of concrete structures using radar techniques is increasingly being recognised as an effective way of gathering information. The numerical simulation of this type of inspection may help to minimise the overall cost of an investigation and to increase the likelihood of carrying out fully effective maintenance and repai...

To be effective a perfectly matched layer (PML) must be reflectionless to all impinging waves over a broad band of frequencies whilst not overly increasing the computational burden. This can be difficult to achieve as one must find a balance between the discretization error, the number of PML layers and the reflection coefficient. This work present...

In order to resolve closely spaced targets in a planar surface normal to the beam, the antenna used in the radar assessment of concrete structures should have a narrow beam width which means a higher directivity. This work presents a procedure to optimize the field pattern of a bow-tie antenna using multi-objective genetic algorithms in conjunction...

This paper addresses the problem of inverting Ground Penetrating Radar (GPR) data, to find the buried inclusions characteristics depth and radii considering a non- homogenous host media by using neural networks (NN). The aim is the detection and characterization of inclusions in concrete structures. A novel asynchronous model is proposed to the NN...

We are investigating the radar as a non-destructive technique to detect early-stage flaws and reinforcement in concrete structures. In this paper, we simulate the ground-penetrating radar (GPR) assessment of concrete structures using three-dimensional (3D) finite-difference time-domain (FDTD). The discussion focuses on the evaluation of the perform...

Le béton est un des matériaux de construction principaux dans les grandes infrastructures telles les routes, les ponts et les centrales électriques. Pour évaluer l'évolution du béton dans ces structures, le contrôle non destructif est une des techniques les plus répandues. Elle fournit des informations non perceptibles a l'oeil humain ce que ne per...