Search

The main objective of this paper is to Identify which macroe conomic factors and industrial indexes influenced the total Brazilian banking spread between March 2011 and March 2015. This paper considers subclassification of industrial activities in Brazil. Monthly time series data were used in multivariate linear regression models using Eviews (7.0). Eighteen variables were considered as candidates to be determinants. Variables which positively influenced bank spread are; Default, IPIs (Industrial Production Indexes) for capital goods, intermediate goods, du rable consumer goods, semi-durable and non-durable goods, the Selic, GDP, unemployment rate and EMBI +. Variables which influence negatively are; Consumer and general consumer goods IPIs, IPCA, the balance of the loan portfolio and the retail sales index. A p-value of 05% was considered. The main conclusion of this work is that the progress of industry, job creation and consumption can reduce bank spread. Keywords: Credit. Bank spread. Macroeconomics. Industrial Production Indexes. Finance., Comment: in Portuguese langauge. Keywords: Credit. Bank spread. Macroeconomics. Industrial Production Indexes. Finance

A new system, called SELA -- Auditing Electronic System, has been developed to be applied to the Brazilian Electronic Voting Machine. The SELA was designed to use open hardware and software, making it widely known by society. The security of the auditing process is guaranteed by the application of a Fingerprint Algorithm, a Hash Function. This system is robust and requires minimal modifications to the Electronic Voting Machine. In this paper, SELA is described, and its use during the election process is analyzed. A comparison between SELA and the use of thermal printers as a secondary voting record system is also presented. The authors recommend a pilot implementation of SELA for the 2002 Brazilian Elections., Comment: 7 pages, in Portuguese language, 3 figures, prototype

Women and gender-diverse people represent an important constituency in the food value chain. Among all working women globally, about one in three works upstream in the food value chain. These women face increasing barriers to safety, recognition and advancement. Yet very little about their experiences has been documented. In the limited instances where the women who power global supply chains have been put into focus, most have concentrated on the experiences of women workers in the apparel sector., Through desktop research, one-on-one interviews with local organizations, case studies and workshops, this paper provides information and guidance on how investors, who are well-positioned to encourage companies to advance gender equity upstream in company supply chains, can help reshape this narrative and encourage companies to act.

In this paper, we propose the replication of scientific experiments, with the participation of the general public, as one of the possible strategies to confront science deniers. Using the social media of the Federal University of Lavras (UFLA), the project entitled : The Magic of Physics and the Universe, invited the public to reproduce the experiment carried out by the Greek Eratosthenes over 2,100 years ago, which he proved that the Earth is spherical. We present a report of this experience to suggest that it is possible for citizens to experience scientific knowledge and observe the phenomena in a simple way, in order to develop a critical interpretation of false information that circulates in society. This proposal distinctively geeks to deconstruct the denial of the Earth's curvature through direct and collective participation of citizens in Eratosthenes' experiment, which permit more reflection on how the scientific method used to study this subject works., Comment: This article is written in Portuguese

This paper analyzes the redistributive impacts of indirect taxation reforms in Brazil inspired by PEC 45/2019, particularly in the version that led to EC 132/2023. Comparisons are made between the current system and the simulated reforms, considering the distribution of the tax burden among families in different income classes, as well as the impact on poverty and inequality indicators. The simulations are conducted based on the combination of effective tax rates that apply to goods and services consumed by households, using nationally representative microdata from family budgets., Comment: in Portuguese language

This study aims to discuss the impacts of a low-cost airline on the air transport market and, especially, to present the most recent findings from specialized literature in the field. To this end, various works on this topic, published since 2015, were selected and analyzed. From this analysis, it was possible to categorize the main topics discussed in the papers into five groups: (i) the impacts of a low-cost airline on competing airlines; (ii) impacts on airports; (iii) general impacts on the demand for air transport; (iv) effects on passengers' choice process; and (v) general effects on a geographical region., Comment: This article is written in Portuguese

The conservation of tropical forests is a current subject of social and ecological relevance due to their crucial role in the global ecosystem. Unfortunately, millions of hectares are deforested and degraded each year. Therefore, government or private initiatives are needed for monitoring tropical forests. In this sense, this work proposes a novel framework, which uses of distribution estimation algorithm (UMDA) to select spectral bands from Landsat-8 that yield a better representation of deforestation areas to guide a semantic segmentation architecture called DeepLabv3+. In performed experiments, it was possible to find several compositions that reach balanced accuracy superior to 90% in segment classification tasks. Furthermore, the best composition (651) found by UMDA algorithm fed the DeepLabv3+ architecture and surpassed in efficiency and effectiveness all compositions compared in this work., Comment: in Portuguese language. Best Paper Award at the Workshop of Undergraduate Works (WUW), SIBGRAPI 2023

This paper presents a comparative analysis of three routing strategies in opportunistic quantum networks. Quantum communication networks face unique challenges, such as the fragility of qubits and the need to create and maintain pairs of entangled states for reliable transmission. In this context, efficient and reliable routing is crucial to maximize the fidelity of the established routes, minimize the creation of new entangled pairs, and reduce the need for route recalculation. The routing strategies are compared based on the fidelity of the chosen routes, the number of entangled pairs created, and the number of route recalculations. The results obtained provide valuable information for the design and optimization of opportunistic quantum networks, contributing to advances in the efficiency and reliability of quantum communications., Comment: XIII Confer\^encia Nacional em Comunica\c{c}\~oes, Redes e Seguran\c{c}a da Informa\c{c}\~ao, in Portuguese language

Training machine learning models for predicting stock market share prices is an active area of research since the automatization of trading such papers was available in real time. While most of the work in this field of research is done by training Neural networks based on past prices of stock shares, in this work, we use iFeel 2.0 platform to extract 19 sentiment features from posts obtained from microblog platform Twitter that mention the company Petrobras. Then, we used those features to train XBoot models to predict future stock prices for the referred company. Later, we simulated the trading of Petrobras' shares based on the model's outputs and determined the gain of R$88,82 (net) in a 250-day period when compared to a 100 random models' average performance., Comment: in Portuguese language, Presented at: 1o Semin\'ario de Ci\^encia de Dados do IFSP. Campinas: 2023

This study presents a comprehensive methodology for modeling and forecasting the historical time series of fire spots detected by the AQUA_M-T satellite in the Amazon, Brazil. The approach utilizes a mixed Recurrent Neural Network (RNN) model, combining Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) architectures to predict monthly accumulations of daily detected fire spots. A summary of the data revealed a consistent seasonality over time, with annual maximum and minimum fire spot values tending to repeat at the same periods each year. The primary objective is to verify whether the forecasts capture this inherent seasonality through rigorous statistical analysis. The methodology involved careful data preparation, model configuration, and training using cross-validation with two seeds, ensuring that the data generalizes well to the test and validation sets, and confirming the convergence of the model parameters. The results indicate that the mixed LSTM and GRU model offers improved accuracy in forecasting 12 months ahead, demonstrating its effectiveness in capturing complex temporal patterns and modeling the observed time series. This research significantly contributes to the application of deep learning techniques in environmental monitoring, specifically in fire spot forecasting. In addition to improving forecast accuracy, the proposed approach highlights the potential for adaptation to other time series forecasting challenges, opening new avenues for research and development in machine learning and natural phenomenon prediction. Keywords: Time Series Forecasting, Recurrent Neural Networks, Deep Learning., Comment: 16 pages, in Portuguese language, 24 figures

The importance of implementing unitarity constraints in meson spectroscopy is very briefly outlined for Portuguese students of engineering sciences and therefore non-experts in the field. After explaining the profound differences between meson spectroscopy and atomic spectroscopy, attention is paid to the shortcomings of standard Breit-Wigner parametrisations in the case of broad and/or overlapping resonances. Finally, the manifestly unitary Resonance-Spectrum-Expansion model, which lies at the heart of a recent invited review paper by the present authors, is graphically presented, together with a simple yet typical application to the long-controversial $K_0^\star(700)$ resonance., Comment: in Portuguese. Invited paper for the first new edition (no. 504) of the students journal "T\'{e}cnica" published on 3 November 2021 by the "Associa\c{c}\~{a}o dos Estudantes do Instituto Superior T\'{e}cnico" of IST in Lisbon, Portugal. Article is in Portuguese language, with an English abstract; 4 pages, 5 figures. Link to published version: https://www.paperturn-view.com/?pid=MTk197448&p=25&v=1.1

In this article, we present several apparent paradoxes of special relativity and their respective solutions. These paradoxes have appeared since the advent of relativity in 1905, and in fact they are never paradoxes. From a didactic point of view, paradoxes are an excellent learning tool. They lead the student to confront, and abandon, several central concepts of Galilean theory, such as simultaneity and rigidity of extended bodies. In particular, we review a new and simple solution to the twin paradox, recently found by one of the present authors [1]. It does not need to consider reference accelerators or light signals, which are the solutions presented in the literature., Comment: in Portuguese language, paper accepted for publication in Revista Brasileira do Ensino de F\'isica

Recent works have demonstrated how Linear Parameter Varying Model Predictive Control (LPV MPC) algorithms are able to control nonlinear systems with precision and reduced computational load. Specifically, these schemes achieve comparable performances to state-of-the-art nonlinear MPCs, while requiring the solution of only one quadratic programming problem (thus being real-time capable). In this tutorial paper, we provide a step-by-step overview of how to implement such LPV MPC algorithms, covering from modelling to stability aspects. For illustration purposes, we consider a realistic implementation for a gas-lift petroleoum extraction process, comparing the LPV approach with the becnhmark nonlinear MPC software CasADi., Comment: Main text in portuguese, submitted to the 2023 Simp\'osio Brasileiro de Automa\c{c}\~ao Inteligente (SBAI 2023)

The purpose of this paper (which, in many passages, I take the liberty of writing in the first person singular for bringing a personal experience) is to show how teachers of Physics and Mathematics in Basic Education can teach, through a simple and playful activity, the rules of signs that are related to basic arithmetic operations involving positive and negative numbers. How? By using a ruler, or any other object that can be interpreted as a number line, and a flat mirror. By the way, as the justification of why this method works is physical and mathematical, this paper provides a succinct review on the formation of images by flat and spherical mirrors since some teachers of Mathematics may (just as a possibility) not know how it happens. Lastly, given the interdisciplinary nature of this activity, some additional considerations are also presented regarding how these teachers can use it to instigate the students to observe how Physics and Mathematics, together, are part of everyday life for all of us., Comment: 35 pages, 16 figures (this paper was purposely/exceptionally written in portuguese)

Society is changing, has always changed, and will keep changing. However, changes are becoming faster and what used to happen between generations, now happens in the same generation. Computing Science is one of the reasons for this speed and permeates, basically, every other knowledge area. This paper (written in Portugu\^es) describes, briefly, the worldwide initiatives to introduce Computing Science teaching in schools. As the paper's main conclusion, it is essential to introduce Computing Science and Computational Thinking for kids before they enter into a university., Comment: 9 pages, in Portuguese. Published as a chapter in the book "Desafios da Educa\c{c}\~ao T\'ecnico-Cient\'ifica no Ensino M\'edio". 1ed.Rio de Janeiro: Academia Brasileira de Ci\^encias, 2018

Application services often support mobile and web applications with REST interfaces, implemented using a set of distributed components that interact with each other. This approach allows services to have high availability and performance at a lower cost than a monolithic system. However, the existence of multiple components makes the development process of these systems more complex and therefore susceptible to errors. In this paper, we present JepREST, a system that automates the use of Jepsen libraries to test the correctness of distributed applications that provide a REST interface. Based on a service interface specification, JepREST generates and executes a set of tests with multiple clients performing operations concurrently, subsequently verifying if the system behaviour is linearizable. The preliminary evaluation shows that JepREST simplifies the testing of REST applications., Comment: in Portuguese language

We present the second part of a series of papers proposing a novel teaching sequence for Particle Physics in high school. The topic of the present work is Nuclear Physics. The goal of the sequence is to approach the subject in a way as to stimulate scientific literacy, from a perspective involving Science, Technology, Society and Environment (STSE). We evaluate the potentialities and effectiveness of the material proposed here, allied to a dialogical approach by the teacher, by analyzing the presence of scientific literacy and engagement indicators during interventions applied to a public school in Esp\'irito Santo, Brazil., Comment: 31 figures, in portuguese

Currently, transport planning has changed its paradigm from projects oriented to guarantee service levels to projects oriented to guarantee accessibility to opportunities. In this context, a number of studies and tools aimed at calculating accessibility are being made available, however these tools depend on job location data that are not always easily accessible. Thus, this work proposes the creation of a database with the locations of formal jobs in Brazilian cities. The method uses the RAIS jobs database and the CNEFE street faces database to infer the location of jobs in urban regions from the zip code and the number of non-residential addresses on street faces. As a result, jobs can be located more accurately in large and medium-sized cities and approximately in single zip code cities. Finally, the databases are made available openly so that researchers and planning professionals can easily apply accessibility analyzes throughout the national territory., Comment: 9 pages, in Portuguese language, 3 figures, 1 table, Data presentation paper

In this paper, we present the Quantum Information Software Developer Kit - Qiskit, for teaching quantum computing to undergraduate students, with basic knowledge of quantum mechanics postulates. We focus on presenting the construction of the programs on any common laptop or desktop computer and their execution on real quantum processors through the remote access to the quantum hardware available on the IBM Quantum Experience platform. The codes are made available throughout the text so that readers, even with little experience in scientific computing, can reproduce them and adopt the methods discussed in this paper to address their own quantum computing projects. The results presented are in agreement with theoretical predictions and show the effectiveness of the Qiskit package as a robust classroom working tool for the introduction of applied concepts of quantum computing and quantum information theory., Comment: This is a didactic text written in Portuguese by undergraduate physics students under the supervision of Professor Clebson Cruz. This paper summarizes the class notes, activities, and projects developed by students of the Applied Quantum Computing course at the Federal University of Western Bahia - Brazil

Non-linear dynamics is not a usually covered topic in undergraduate physics courses. However, its importance within classical mechanics and the general theory of dynamical systems is unquestionable. In this work we show that this subject can be included in the schedule of an introductory classical mechanics course without the need to develop a robust theory of chaotic dynamics. To do this, we take as examples conservative non-linear oscillators subject to time-dependent periodic forces. By introducing the concept of stroboscopic maps we show that it is possible to visualize the appearance of chaos in these systems. We also address the example of the forced simple pendulum applying the same treatment. Finally, we briefly comment on the more general theory of chaos in conservative Hamiltonian systems., Comment: 14 pages, 16 figures. Accepted for publication in "Revista Brasileira de Ensino de F\'isica". Written in Portuguese

Under extreme conditions of temperature and pressure, it is believed that quarks and gluons (particles that mediate the interaction between quarks) can be "free" in a given volume. This hypothetical phase of matter is called plasma of quarks and gluons, QGP for its acronym in English. It is speculated that it existed in the first moments after the \textit{Big Bang} and that it exists inside N\^eutron stars due to the enormous energy density in these places. These conditions of very high temperature and energy density can be reproduced in the laboratory with the collision of heavy ions in an ultra-relativistic regime in accelerators such as the RHIC and the LHC. However, due to the extremely short duration of the QGP phase after the collision, we were unable to directly observe the plasma, only the so-called \textit{final observables}, such as the particles generated by this set of quarks, gluons and energy and the distribution of momentum of these particles. Therefore, mathematical modeling is an essential tool in understanding the behavior of the system, for example, to have an idea of the value of viscosities in this phase., Comment: 9 pages, in Portuguese language

The covariance of the d'Alembert equation for acoustic phenomena, described by mechanical waves in one or three spatial dimensions, under Galilean transformations, is demonstrated without the need to abandon the hypothesis that time is absolute in Classical Mechanics. This is true only if and only if the phase velocity of sound depends on the velocity of the observer. On the other hand, it is also shown that the same d'Alembert equation is covariant under Lorentz transformations if and only if the phase velocity of light does not depend on the observer., Comment: 11 pages, in Portuguese

The Pythagorean Theorem is one of the oldest, more famous and more useful theorems of Mathematics, and possibly the one that has had the most impact in the evolution of this and other sciences. In this article, we look at it from different perpectives, some of them uncommon. We recall some of its history, some well known applications and generalizations, other less known ones, and show it still has many surprising facets which are usually ignored. (O Teorema de Pit\'agoras (TP) \'e um dos mais antigos, famosos e \'uteis teoremas da Matem\'atica, e possivelmente o que maior impacto teve na evolu\c{c}\~ao desta e outras ci\^encias. Neste artigo, vamos olhar para este velho conhecido de diferentes perspectivas, algumas pouco usuais. Iremos lembrar um pouco da sua hist\'oria, algumas aplica\c{c}\~oes e generaliza\c{c}\~oes bem conhecidas, outras nem tanto, e ver que ele guarda muitas facetas surpreendentes e geralmente ignoradas.), Comment: in Portuguese language

Considering a pair of genomes, the goal of rearrangement distance problems is to estimate how distant these genomes are from each other based on genome rearrangements. Seminal works in genome rearrangements assumed that both genomes being compared have the same set of genes (balanced genomes) and, furthermore, only the relative order of genes and their orientations, when they are known, are used in the mathematical representation of the genomes. In this case, the genomes are represented as permutations, originating the Sorting Permutations by Rearrangements problems. The main problems of Sorting Permutations by Rearrangements considered DCJs, reversals, transpositions, or the combination of both reversals and transpositions, and these problems have their complexity known. Besides these problems, other ones were studied involving the combination of transpositions with one or more of the following rearrangements: transreversals, revrevs, and reversals. Although there are approximation results for these problems, their complexity remained open. Some of the results of this thesis are the complexity proofs for these problems. Furthermore, we present a new 1.375-approximation algorithm, which has better time complexity, for the Sorting Permutations by Transpositions. When considering unbalanced genomes, it is necessary to use insertions and deletions to transform one genome into another. In this thesis, we studied Rearrangement Distance problems on unbalanced genomes considering only gene order and their orientations (when they are known), as well as Intergenic Rearrangement Distance problems, which incorporate the information regarding the size distribution of intergenic regions, besides the use of gene order and their orientations (when they are known). We present complexity proofs and approximation algorithms for problems that include reversals and transpositions., Comment: PhD Dissertation, in Portuguese, presented at the Institute of Computing - Unicamp in March 2024

Linguistic ambiguity continues to represent a significant challenge for natural language processing (NLP) systems, notwithstanding the advancements in architectures such as Transformers and BERT. Inspired by the recent success of instructional models like ChatGPT and Gemini (In 2023, the artificial intelligence was called Bard.), this study aims to analyze and discuss linguistic ambiguity within these models, focusing on three types prevalent in Brazilian Portuguese: semantic, syntactic, and lexical ambiguity. We create a corpus comprising 120 sentences, both ambiguous and unambiguous, for classification, explanation, and disambiguation. The models capability to generate ambiguous sentences was also explored by soliciting sets of sentences for each type of ambiguity. The results underwent qualitative analysis, drawing on recognized linguistic references, and quantitative assessment based on the accuracy of the responses obtained. It was evidenced that even the most sophisticated models, such as ChatGPT and Gemini, exhibit errors and deficiencies in their responses, with explanations often providing inconsistent. Furthermore, the accuracy peaked at 49.58 percent, indicating the need for descriptive studies for supervised learning., Comment: in Portuguese language, 16 p\'aginas, 5 p\'aginas de ap\^endice e 4 imagens

Introduction and Objective. Assuming the need to rethink Education and its function as an element of social transformation and generator of a profound ethical change and promoter of other ways of being on planet Earth, this study seeks to understand the possible dialogues between Earth Pedagogy and Astrobiology in the construction and proposition of continuing education processes for science teachers. Methodology. A mini-course was promoted aimed at teachers and an attempt was made to report the construction process of the training process and, using Content Analysis, to analyze the contributions pointed out by the participants to their training and teaching practice. Results and Conclusion. The dialogue between knowledge in the continuing education of teachers contributes with fundamental elements to teaching practice, covering cognitive, emotional, individual and collective aspects, as well as highlighting the role of the university in promoting initiatives that bring Education and Complexity together., Comment: This article is written in Portuguese

In this work we study the dynamics in an apocalypse where the individuals can temporarily become zombies, returning to the living state again or die. We describe this dynamics using a modified version of the epidemic SIS model. The zombies can die when in contact with a terminator, which is part of the living people. To define the possible interactions we use an Erd\"{o}s-R\`{e}nyi network and we calculate how the absorbing and active phase of the original SIS model is influenced by the average network degree. We also use the component and domain distribution of the network to understand how this influence occurs., Comment: 8 pages, in Portuguese, 10 figures, conference paper

This paper presents our efforts to build a robust ASR model for the shared task Automatic Speech Recognition for spontaneous and prepared speech & Speech Emotion Recognition in Portuguese (SE&R 2022). The goal of the challenge is to advance the ASR research for the Portuguese language, considering prepared and spontaneous speech in different dialects. Our method consist on fine-tuning an ASR model in a domain-specific approach, applying gain normalization and selective noise insertion. The proposed method improved over the strong baseline provided on the test set in 3 of the 4 tracks available, Comment: Proceedings of the First Workshop on Automatic Speech Recognition for Spontaneous and Prepared Speech & Speech Emotion Recognition in Portuguese (SE&R 2022), co-located with PROPOR 2022

In this paper we describe one of the most promising platforms for the construction of a universal quantum computer, which consists of a chain of $N$ ions trapped in a harmonic potential, whose internal states work out as qubits, and are coupled to collective vibrational modes of the chain. From such coupling, it is possible to build interactions between different ions of the chain, that is, qubit-qubit interactions that, together with individual operations on the ions, allow building a quantum computer as first proposed by Cirac and Zoller in the 1990s [Phys. Rev. Lett. 74, 4091 (1995)]. Here we discuss from the physics involved in trapping ions in electromagnetic potentials to the Hamiltonian engineering needed to generate a universal set of logic gates, fundamental for the execution of more complex quantum algorithms. Finally, we present the current state of the art of quantum computing in trapped ion systems, highlighting recent advances made by companies and government projects that use such architecture, such as IonQ and AQTION., Comment: 18 pages, in Portuguese language, 8 figures

In the research on FANETs (Flying Ad-Hoc Networks) and distributed coordination of UAVs (Unmanned Aerial Vehicles), also known as drones, there are many studies that validate their proposals through simulations. Simulations are important, but beyond them, there is also a need for real-world tests to validate the proposals and enhance results. However, field experiments involving drones and FANETs are not trivial, and this work aims to share experiences and results obtained during the construction of a testbed actively used in comparing simulations and field tests., Comment: in Portuguese language

We propose a physical mechanism for fine-tuning the phase of a domain wall around the equilibrium directions involving the application of an external field and a spin polarized current in opposite directions. In this way, the position of the domain wall remains unchanged, but its phase can be slightly modified around the initial equilibrium positions, applying the external field/current smoothly. We point out a few applications to which this fine tuning may lead., Comment: Written in portuguese. Submited to Revista Brasileira de Ensino de Fisica on March 15 2024

Blockchain technology has emerged as a necessity for the decentralization of payment methods and transactions, but it has brought with it many properties of distributed systems that have made it a crucial technology for overcoming some of society's challenges, especially in the context of decentralizing services, transparency of information, availability, and security. Its architecture and communication methods, although possessing some complex nuances to understand, particularly for the lay audience in the field of distributed systems, protocols, and computer networks. In this article, we will explore some topics of distributed systems related to blockchain technology., Comment: in Portuguese language

The growing interaction between traditional knowledge and formal sciences emerges as a relevant field of research. In this perspective, the aim of this article is to investigate the intersections between Physics and traditional knowledge in the ceramics practices of Vila Cuera, in Bragan\c{c}a, state of Para. Using an ethnographic approach, complemented by qualitative analysis, we realize that ceramists use their sensitive intuition and, masterfully, apply thermodynamic principles in the production of handmade ceramics. The results highlight the value of Ethnophysics, underlining that, long before the formal structuring of science as we know it, traditional societies already practiced and understood natural phenomena in tune with contemporary physical principles. We conclude that there is an inherent link between Physics and traditional knowledge with regard to the traditional ceramics practice, grounded on empirical observations and ancestral wisdom, that dialogues with science in a complementary relationship. The study highlights the importance of valuing and recognizing the knowledge of traditional populations by highlighting the knowledge doings of cultures and institutionalized science., Comment: in Portuguese

Since the development of lasers, we have continuously sought to advance techniques and theory to obtain beams with a high degree of coherence, as natural light sources provide incoherent light. However, there are applications where it is advantageous to use partially coherent (PC) beams in a controlled manner, such as in propagation through turbulent media. To generate a PC beam in the laboratory or in simulations, specific theories and methods are required. In this article, we provide an introduction to PC beam theory, describing how to generate them through modal decompositions and a step-by-step guide for simulating and analyzing beam generation inspired by experiments. To illustrate the methods, we present Gaussian Schell-Model beams as an example., Comment: 12 pages, in Portuguese language, 11 figures

In this study, we will address some topics related to the privatization of airports in the scientific literature, in an attempt to provide an answer to the following question: does the privatization of airports bring positive results? Firstly, we turn our attention to the motivations leading to privatization, considering the two main parties involved, the government and the private sector. After all, the success of such a decision will be relative to the reasons that justify it. In a second moment, we will consider the regulatory issue, whose influence on the airport's financial performance is consolidated in the literature. In the third part, we address the main documented results of privatization, with special attention to productive efficiency, whose improvement is the most popular motivation for privatization., Comment: This article is written in Portuguese

This work focuses on trying to understand how the construction of an airline's network is made. For this purpose, the case of Azul was studied, investigating which and how factors affect the decision of this airline to enter domestic routes, in addition to analyzing how the merger of Azul with the regional airline Trip affected the company's network planning. For this, an academic study was conducted using an econometric model to understand the airline's entry model. The results show that Azul's business model is based on connecting new destinations, not yet served by its competitors, to one of its hubs, and consistently avoiding routes or airports dominated by other airlines. Regarding the effects of the merger, the results suggest that Azul moved away from its original entry model, based on JetBlue, to a model more oriented towards regional aviation, entering shorter routes and regional airports., Comment: This article is written in Portuguese

In recent years, the topic of global warming and greenhouse gas emissions has been increasingly in the media. This theme has raised various flags, showing concern for the future and seeking alternatives for a more sustainable life over the years. When studying greenhouse gas emissions, one of the main emitters of such gases is the burning of fuels, in which transport vehicles that depend on gas and oil are included. In this respect, air transport through aircraft is one of the sources emitting such gases. Aiming to reduce gas emissions, one of the ways to do this is by reducing fuel consumption; for this, aircraft would have to be more efficient, or the offer and demand for flights would be reduced. However, what if aircraft fuel consumption were taxed? What would be the effects of this on air transport? Could this be one of the alternatives to reduce emissions? To understand this relationship between taxation and a possible reduction in fuel consumption, a study was developed by the Aeronautics Institute of Technology (ITA), using an econometric model to understand how demand would be affected by changes in airfares. In addition, a simulation of possible environmental taxes on the values of air tickets was carried out to analyze the demand response and to get an idea if this taxation would really solve the emission problems., Comment: This article is written in Portuguese

The exploration of existing commercial opportunities has been increasing the share of commercial (non-aeronautical) revenues in the total revenues of airports worldwide. These revenues, also called commercial, non-aeronautical, or non-tariff revenues, come from rentals, duty-free shops, food and beverage sales, parking, advertising, etc. In other words, everything that is not the main business of the airport. Consequently, the dependence on commercial revenues has also become increasingly important, and airport managers are interested in understanding how to improve their financial results with this new revenue source, as it not only improves financial outcomes but also optimizes passengers' time and money consumption options at airports. Therefore, this chapter seeks to discuss the main determinants of commercial revenues at national airports, analyzing the possible impacts of the behavior of passengers from low-cost carriers (LCC) on these revenues, combined with other determining factors., Comment: This article is written in Portuguese

This study addresses the growing standardization of airline fleets, highlighting that frequent passengers are more likely to fly on the same aircraft model more often. The objective is to analyze the fleet management of airlines and the impact of a reduced variety of models on company operations. The benefits of standardization, such as operational efficiency, and the risks, such as vulnerability to specific model failures, are discussed. The work reviews international scientific literature on the subject, identifying consensus and disagreements that suggest areas for future research. It also includes a study on the Brazilian market, examining how standardization affects operational costs and profitability in terms of model, family, and aircraft manufacturer. Furthermore, the relationship between fleet standardization and the business model of the companies is investigated, concluding that the advantages of standardization are not exclusive to low-cost companies but can also be leveraged by other airlines., Comment: This article is written in Portuguese

This study explores the approaches used by airlines in setting flight times. It highlights the need to balance operational and strategic factors, such as optimizing the use of resources - including aircraft, crew, and fuel - and managing the risks related to delays and congestion. The work details a national analysis focused on domestic flights, investigating the factors that influence companies to adjust scheduled flight times and the impact of this practice on punctuality. The results indicate that decisions about flight time are influenced by both operational and strategic aspects, being affected by competition and the sector's policies on punctuality and slot allocation. Furthermore, it was found that adding extra time is an effective strategy for reducing delays, although it may conceal system deficiencies., Comment: This article is written in Portuguese

This work presents an analysis of recent literature examining factors that influence flight times in Brazil, with special attention to the impact of new technology implementations, specifically Performance-Based Navigation (PBN). PBN procedures began to be implemented in Brazilian airspace in 2009 and represent a new concept of air navigation, using satellites to create 3D flight routes that are shorter and more precise, potentially reducing the distances flown and consequently flight times and delays. Flight times depend on various factors, such as the size and complexity of the origin and destination airports, weather conditions, aircraft models, and how full the flights are. Therefore, to assess the impact of the new procedures, the variation in this set of factors must be taken into account. The results found in the literature suggest that Performance-Based Navigation had a positive impact, reducing flight times by about 1-2%, representing a saving of tens of thousands of flight hours from the beginning of implementations in 2009 until the end of 2018., Comment: This article is written in Portuguese

Flight delays are a reality in the modern air industry worldwide. However, studies in the literature have investigated the competitive determinants of delays arising from factors originating at the airport and along the route separately. This work aims to present a national study that used a unifying approach from the literature, considering the local and global effects of competition on delays. The analysis took into account a phenomenon known as the "internalization of externalities" of airport congestion. Furthermore, it discusses the relationship between quality and competition on the route and the impacts of the entry of a low-cost carrier (LCC) on the delays of incumbent airlines in the Brazilian air market. The literature suggests that there is evidence of congestion internalization at Brazilian airports, in parallel with competition for quality at the route level. Additionally, the potential competition caused by the presence of the LCC leads to a global effect that suggests the existence of impacts other than prices on routes where it has not entered., Comment: This article is written in Portuguese

This study discusses the literature on the convergence of business models of airlines in Brazilian air transport, focusing on the formation of flight networks. Initially, it analyzes the determinants of the network formation patterns of the "fundamental" business models (archetypes) of airlines in the first years after the sector's deregulation. Then, it discusses how the business models of Brazilian companies resemble these patterns. The literature highlights convergences between the network formation strategies of full-service companies in relation to older low-cost companies, in addition to business model redirections after mergers and acquisitions., Comment: This article is written in Portuguese