Rafael Timoteo de Sousa Junior

University of Brasília | UnB · Department of Electrical Engineering

The trust is always present implicitly in the protocols based on cooperation, in particular, between the entities involved in routing operations in Ad hoc networks. Indeed, as the wireless range of such nodes is limited, the nodes mutually cooperate with their neighbors in order to extend the remote nodes and the entire network. In our work, we are...

Accurate attitude estimation is crucial for Unmanned Aerial Vehicles (UAVs) in order to facilitate automated activities such as landing or trajectory tracking. Recently antenna array based communication systems have been installed in UAVs. This array structure can also be applied for attitude estimation by computing the line-of-sight (LOS) path bet...

In This work we propose a new distributed intrusion detection system (IDS) designed for mobile ad hoc network (MANET) environments. The complete distribution of the intrusion detection process is the salient feature of our proposition: distribution is not restricted to data collection but also applied to execution of the detection algorithm and ale...

ntrusion detection systems (IDS) are essential com- ponents in a secure network environment, allowing for early detection of malicious activities and attacks. By employing information provided by an IDS it is possible to apply appropriate countermeasures and mitigate attacks that would otherwise seriously undermine network security. However, curren...

This paper proposes an application programming interface (API) for accessing services within the internet of things (IoT) through both REST and SOAP protocols. This API provides methods and procedures to allow its usage for performing IoT control and event monitoring operations. In order to encompass devices diversity, the proposed API introduces a...

User behavior anomaly detection has been a successful measure contributing to cybersecurity. Much of the related literature addresses this issue without considering the individualization of users when analyzing logs generated by network and system protection devices. This paper presents WEAPON, an architecture for the detection of behavior anomalie...

The process of identifying and managing Information and Communication Technology (ICT) risks has become a concern and a challenge for public and private organizations. In this context, risk management methodologies within the Brazilian Federal Public Administration organizations have become indispensable to help the managers of these organizations...

Passive optical networks (PONs) are an important and interesting technology for broadband access as a result of the growing demand for bandwidth over the past 10 years. An arduous and complex step in the design of such networks involves determining the placement of equipment, optical fiber cables and several other parameters relevant to the proper...

As impressões digitais se configuram em uma das biometrias mais utilizadas na distinção de pessoas. Tal fato se baseia em importantes características que apresentam: estabilidade após o desenvolvimento completo, fácil classificação dos padrões de desenhos, coleta pouco invasiva e singularidade ao longo da vida de um indivíduo. Neste estudo, foram m...

Organic compounds have been employed in developing new green energy solutions with good cost-efficiency compromise, such as photovoltaics. The light-harvesting process in these applications is a crucial feature that still needs improvements. Here, we studied natural dyes to propose an alternative for enhancing the light-harvesting capability of pho...

Recently, a new two-dimensional carbon allotrope named biphenylene network (BPN) was experimentally realized. The BPN structure consists of four-, six-, and eight-membered rings of sp2-hybridized carbon atoms. In this work, we carried out fully-atomistic reactive (ReaxFF) molecular dynamics simulations to study the mechanical properties and fractur...

Fingerprints do not repeat, varying from region to region on the same fingerprint and from person to person. Using this morphological exclusivity in the individualization of people is considered one of the most reliable methods of identification worldwide. Many populations have been studied with respect to sex determination from fingerprints. In th...

Automatized scalable healthcare support solutions allow real-time 24/7 health monitoring of patients, prioritizing medical treatment according to health conditions, reducing medical appointments in clinics and hospitals, and enabling easy exchange of information among healthcare professionals. With recent health safety guidelines due to the COVID-1...

Managing and evolving a chatbot’s content is a laborious process and there is still a lack of standardization. In this context of standardization, the absence of a management process can lead to bad user experiences with a chatbot. This work proposes the Chatbot Management Process, a methodology for content management on chatbot systems. The propos...

Resource efficiency and survivability are critical concerns in elastic optical networks (EONs) with virtualization. In this paper, we investigate some important aspects in network survivability design against single-link failure under dedicated protection and bandwidth squeezing schemes when multiple virtual topologies are employed. We propose a li...

Information security incidents currently affect organizations worldwide. In 2021, thousands of companies suffered cyber attacks, resulting in billions of dollars in losses. Most of these events result from known vulnerabilities in information assets. However, several heterogeneous databases and sources host information about those flaws, turning th...

A jurisprudence search system is a solution that makes available to its users a set of decisions made by public bodies on the recurring understanding as a way of understanding the law. In the similarity of legal decisions, jurisprudence seeks subsidies that provide stability, uniformity, and some predictability in the analysis of a case decided. Th...

Carbon nano-onions (CNO) are multilayered fullerenes. They exhibit good electrical conductivity and large surface area, being of interest for several optoelectronic applications. However, it is still an open question what synthesis routes can be used to convert them into diamonds. Here, we used fully atomistic reactive (ReaxFF) molecular dynamics s...

Recently, a new two-dimensional carbon allotrope, named biphenylene network (BPN) was experimentally realized. The BPN structure is composed of four-, six-, and eight-membered rings of sp$^2$-hybridized carbon atoms. In this work, we carried out fully-atomistic reactive (ReaxFF) molecular dynamics simulations to study the thermomechanical propertie...

This paper aims to show how creating a risk plan can be solved with the help of the constructivist multicriteria method. A case study using Multicriteria Decision Aid Constructivist (MCDA-C) was applied, with cybersecurity framework’s controls as a reference. The study was conducted in a large Brazilian bank in Brazil. The relevance of this work is...

Carbon nano-onions (CNO) are multi-shell fullerenes. In the present work, we used fully atomistic reactive (ReaxFF) molecular dynamics simulations to study the dynamics and structural transformations of CNO structures under high-velocity impacts against a fixed and rigid substrate. We considered single and multi-shell CNO (up to six shells) and at...

Brazilian organizations must comply with the Brazilian General Data Protection Law (LGPD) and this need must be carried out in harmony with legacy systems and in the new systems developed and used by organizations. In this article we present an overview of the LGPD implementation process by public and private organizations in Brazil. We conducted a...

Organic semiconductors have been widely employed in developing new green energy solutions with good cost-efficiency compromise, such as Organic Photovoltaics (OPVs). The light-harvesting process in OPVs is a crucial aspect, which still needs improvements. In this context, the Dye-sensitized solar cells (DSSCs) have arisen as a technically and econo...

The development of a software application involves several challenges related to usability and these challenges need to be observed by the teams throughout the development process. The different forms of interaction, between users and the system, increasingly demand adaptation of human behavior. Thus, usability is an important issue, which depends...

The management practicality and economy offered by the various technological solutions based on cloud computing have attracted many organizations, which have chosen to migrate services to the cloud, despite the numerous challenges arising from this migration. Cloud storage services are emerging as a relevant solution to meet the legal requirements...

As smart devices have become commonly used to access internet banking applications, these devices constitute appealing targets for fraudsters. Impersonation attacks are an essential concern for internet banking providers. Therefore, user authentication countermeasures based on biometrics, whether physiological or behavioral, have been developed, in...

Porous graphene (PG) forms a class of graphene-related materials with nanoporous architectures. Their unique atomic arrangements present interconnected networks with high surface area and high pore volume. Some remarkable PG properties, such as high mechanical strength and good thermal stability, have been widely studied. However, their electrical...

The structural similarity between hexagonal boron nitride (h-BN) and graphene nanoribbons allows forming heterojunctions with small chain stress. The insulation nature of the former and the quasi-metallic property of the latter make them attractive for flat optoelectronics. Recently, shapes of graphene and h-BN domains were precisely controlled, cr...

Social media has become a relevant information source for several decision-making processes and for the definition of business strategies. As various sentiment analysis techniques are used to transform collected data into intelligence information, the sentiment classifiers used in these collection environments must be carefully studied and observed...

Document and process digitalization is considered an essential factor for sustainable cities as it facilitates socio-economic interaction and contributes to climate-friendly urban environments and societies. Since digital documents are vulnerable to illegitimate modifications and forgery, there is a risk of these documents being rejected as untrust...

The importance of analyzing data on public health, especially on notifications of disease cases, can play an important role in the overall improvement of the framework for combating epidemics. This type of study proved to be extremely influential during the COVID-19 pandemic, which demanded rapid and specific actions for the management of different...

The COVID-19 pandemic brought some challenges to humanity, such as the need to reduce the circulation of people while still meeting basic needs such as food, health care and education. People with commodities or who belong to risk groups needed to isolate themselves and the world saw several new technologies and business models being launched in a...

Since the rising of graphene, boron nitride monolayers have been deeply studied due to their structural similarity with the former. A hexagonal graphene-like boron-carbon-nitrogen (h-BCN) monolayer was synthesized recently using bis-BN cyclohexane (B2N2C2H12) as a precursor molecule. Herein, we investigated the electronic and structural properties...

The electronic and structural properties of Janus MoSSe/MoX2 (X=S,Se) in-plane heterojunctions, endowed with single-atom vacancies, were studied using density functional theory calculations. The stability of these structures was verified from cohesion energy calculations. Results showed that single-atom vacancies induce the appearance of flat midga...

This paper proposes and evaluates the deployment of an end-to-end, secure, private cloud-based, distributed solution, for users to work, access and share files from their home offices. The solution aims to help corporate and government IT teams to deliver an extended and more secure experience for employees working from home. In this work, NextClou...

O cenário é comum na TI das organizações: de um lado, o time de desenvolvimento, preocupado exclusivamente em entregar aplicações em períodos cada vez menores, sem se preocupar com questões como infraestrutura de TI e o ambiente necessário para dar estabilidade aos softwares desenvolvidos. De outro, o setor de operações que, com os olhos fixos na i...

With a large number of IoT devices currently and growing, it is of great importance to orchestrate them so that all exercises are fully functioning. This project focuses on the creation of low-cost IoT middleware capable of decentralizing responsibilities, processing, and decision making in a network. This work addresses the construction of an IoT...

Pandemic situations require analysis, rapid decision making by managers and constant monitoring of the effectiveness of collective health-related approaches. These works can be more efficient with the help of clearer and more representative views of the data, as well as with the application of other measures and projections of epidemiological natur...

Distributed Denial of Service (DDoS) attacks are one of the most important security threats, since multiple compromised systems perform massive attacks over a victim, overwhelming its bandwidth and/or resources. Such attacks can be detected, for example, by using supervised machine learning based solutions previously trained on large DDoS attack da...

DDoS attacks against distributed networks of IoT devices and applications are increasing. In this scenario, countermeasures must also use distributed security means. This paper proposes a distributed architecture of an intrusion detection system for IoT networks using smart contracts in blockchain. The proposed architecture supports interaction mec...

Realizing fundamental cryptographic primitives with unconditional security is a central topic in information-theoretic cryptography. These primitives can be realized based on physical assumptions, such as the existence of noisy channels, an upper bound on the storage capacity, or the laws of quantum mechanics. Palmieri and Pereira [1] demonstrated...

Enhancing security, privacy, and interoperability of biometric networks and protocols has been a challenge for many research works for many years. The several proposed approaches still need to integrate these three characteristics while showing security evidence for biometric applications. Therefore, this paper proposes a probabilistic scheme to en...

The electronic and structural properties of Janus MoSSe/MoX$_2$ (X=S,Se) in-plane heterojunctions, endowed with single-atom vacancies, were studied using density functional theory calculations. The stability of these structures was verified from cohesion energy calculations. Results showed that single-atom vacancies induce the appearance of flat mi...

A phishing attack is a threat based on fraudulent communication, usually by e-mail, where the cybercriminals, impersonating a trusted person or organization, try to lure and coax a target. Phishing detection approaches that obtain highly representational features from the text of these e-mails are a suitable strategy to counter these threats since...

The structural similarity between hexagonal boron nitride (h-BN) and graphene nanoribbons allows for the formation of heterojunctions with small chain stress. The combination of the insulation nature of the former and the quasi-metallic property of the latter makes this kind of heterostructure particularly interesting for flat optoelectronics. Rece...

Since the rising of graphene, boron nitride monolayers have been deeply studied due to their structural similarity with the former. A hexagonal graphene-like boron-carbon-nitrogen (h-BCN) monolayer was synthesized recently using bis-BN cyclohexane (B2N2C2H12) as a precursor molecule. Herein, we investigated the electronic and structural properties...

In stock markets, investors adopt different strategies to identify a sequence of profitable investment decisions to maximize their profits. To support the decision of investors, machine learning (ML) software is being applied. In particular, deep learning (DL) approaches are attractive since the stock market parameter presents a highly non-linear b...