Repositório UFSCar

O Repositório Institucional da UFSCar (RI UFSCar) é um sistema de informação que visa armazenar, preservar, organizar e disseminar amplamente a produção intelectual dos diversos setores e segmentos da comunidade da UFSCar, provendo o acesso aberto à informação produzida na instituição e registrada como científica, tecnológica, didática, artístico-cultural e técnico-administrativa.

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Caracterização e estimativa de propriedades físico-mecânicas das madeiras de Eucalyptus pellita F.Muell e Pinus oocarpa Schiede ex Schltdl: com o uso da reflexão difusa de infravermelho próximo (NIR)
(Universidade Federal de São Carlos, 2026-08-14) Andrade, Juraci de Andrade; Lima, Israel Luiz; http://lattes.cnpq.br/0285299583699735; https://orcid.org/0000-0002-4868-6414; Longui, Eduardo Luiz; http://lattes.cnpq.br/9268347207438461; https://orcid.org/0000-0002-7610-9147; http://lattes.cnpq.br/6819901760726396; https://orcid.org/0000-0002-8306-4514; Longui, Eduardo Luiz; Freitas, Miguel Luiz Menezes; Zanata, Marcelo; http://lattes.cnpq.br/9268347207438461; http://lattes.cnpq.br/8536113635924828; http://lattes.cnpq.br/2679501421960303; https://orcid.org/0000-0002-7610-9147; https://orcid.org/0000-0001-8882-0908; https://orcid.org/0000-0003-0124-187X
The genera Eucalyptus and Pinus comprise numerous species widely cultivated in reforestation programs for various commercial purposes. Many of these species exhibit high productivity, rapid growth, adaptability to diverse soil and climatic conditions, and excellent wood quality, making them essential sources of raw material for industries such as sawmilling, pulp and paper, steel production, wood-based panels, and bioenergy. However, studies on the wood quality of Eucalyptus pellita and Pinus oocarpa from mature plantations remain limited. Therefore, this study aimed to characterize the physical and mechanical properties of wood from Eucalyptus pellita and Pinus oocarpa plantations aged 31 and 48 years, respectively. Twelve trees of each species were felled, and a 1-m-long log was collected from the base of each tree to obtain samples for the evaluation of physical and mechanical properties. Significant differences were observed between the two species in terms of their physical and mechanical wood properties, which are critical for industrial and structural applications. Eucalyptus pellita wood exhibited higher basic density and lower porosity, characteristics that are desirable for applications requiring high strength and durability. In contrast, Pinus oocarpa wood showed greater shrinkage and higher porosity. Although these characteristics may limit its performance under variable environmental conditions, they may be advantageous for applications requiring lightweight materials. Overall, the results indicate that, despite the higher density and shear strength of Eucalyptus pellita, Pinus oocarpa wood exhibits greater stiffness and porosity, characteristics that should be considered when selecting the most suitable material for specific applications. The observed properties also highlight the importance of selecting wood with low technological variability when manufacturing products that must meet specific quality standards.
Estimação de dados faltantes em séries temporais de irradiação solar: uma abordagem baseada em aprendizado de máquina
(Universidade Federal de São Carlos, 2026-04-06) Santos, Gustavo Silvestre dos; Fernandes, Ricardo Augusto Souza; http://lattes.cnpq.br/0880243208789454; https://orcid.org/0000-0003-2361-6505; http://lattes.cnpq.br/4449311747364885; https://orcid.org/0009-0005-7692-2356; Fernandes, Ricardo Augusto Souza; Montagnoli, Arlindo Neto; Ferrari, Ricardo José; Rabêlo, Ricardo de Andrade Lira; Nogueira, Samuel Lourenço; Palito, Thamyres Tamulla Cavalcante; http://lattes.cnpq.br/0880243208789454; http://lattes.cnpq.br/2903750902988624; http://lattes.cnpq.br/8460861175344306; http://lattes.cnpq.br/2263553634422386; http://lattes.cnpq.br/2287847504423307; http://lattes.cnpq.br/0882441206072709; https://orcid.org/0000-0003-2361-6505; https://orcid.org/0000-0002-4095-3602; https://orcid.org/0000-0003-1197-2553; https://orcid.org/0000-0003-1482-6404; https://orcid.org/0000-0002-3342-7436
This Master’s thesis investigates missing data imputation in solar irradiance time series using machine learning-based approaches. Missing values pose a major challenge for analyses and applications in meteorology and solar energy, where data continuity and quality are essential for climate forecasting and photovoltaic system planning and operation. This study evaluates and compares statistical methods and machine learning models, including Multivariate Imputation by Chained Equations, Autoencoders, Long Short-Term Memory, and Transformers, applied to meteorological data provided by the National Institute of Meteorology. The methodology includes a characterization of missingness patterns and an analysis based on bioclimatic zones, which supports the selection of stations of interest and the incorporation of spatial and climatic context into the imputation process. Experiments were conducted under a controlled masking protocol with evaluation restricted to the missing positions, and results were compared against classical baselines such as linear interpolation. Overall, the findings indicate that models capable of capturing temporal dependencies and leveraging neighborhood information achieve higher robustness, particularly under longer contiguous gaps.
Entre uso e regulamentação: o celular na dinâmica escolar pelo olhar de estudantes e professores.
(Universidade Federal de São Carlos, 2026-06-25) Koga, Lucas Yuri Soares; Freitas, Denise de; http://lattes.cnpq.br/3330976062026878; https://orcid.org/0000-0003-1575-3243; http://lattes.cnpq.br/5571502835134526; https://orcid.org/0009-0008-4121-9136; Carnio, Michel Pisa; Abib, Maria Lucia Vital dos Santos; http://lattes.cnpq.br/0198207700485715; http://lattes.cnpq.br/2193127515795962; https://orcid.org/0000-0003-0429-7633; https://orcid.org/0000-0001-9337-0067
This study examines the perspectives of students and teachers in elementary and secondary education on the impacts of cell phone use and bans in the school environment, considering their implications for pedagogical, social, and professional experiences. Set against the backdrop of the transformations brought about by digital culture, the study seeks to understand the role of cell phones as a mediating factor in relationships within the daily school life and in the learning process. The methodology combines an extensive literature review with the collection of qualitative data, including questionnaires and semi-structured interviews conducted with students and teachers. The analysis links participants’ statements to the educational debate on digital technologies and the challenges posed by their presence in the school context. The results indicate that, although students and teachers recognize that reducing screen time would contribute to improvements in quality of life and interpersonal relationships, both perceive themselves as dependent on the use of these devices, highlighting that the cell phone plays a strong role as an identity prosthesis and that recognition of the benefits of disconnection does not translate into effective behavioral change. It was also found that there is a pedagogical use by default, in which the device compensates for the precarious state of public infrastructure, and that the integration of the device into teaching work has increased algorithmic surveillance and the platformization of daily routines. It can therefore be concluded that the central issue does not lie in the presence or absence of cell phones in schools, but in the way contemporary society has shaped its relationship with digital technologies. The development of a healthier and more democratic digital culture depends on shared responsibility among families, schools, and the government. It is the government’s responsibility to critically monitor the social impacts of the attention economy designed to capture and retain users’ focus and to promote public policies that prioritize collective well-being, without this effort resulting in the expansion of surveillance mechanisms, platformization, and the precariousness of teaching work. Families and schools, in turn, must work in coordination to educate individuals capable of developing balanced habits and a critical understanding of the uses of digital technologies. In this context, educational policies must take on the urgent role of facilitating the development of a critical, ethical, and humane relationship with new technologies.
Armazenamento de hidrogênio em compósito Mg-Fe produzido por reofundição e limagem
(Universidade Federal de São Carlos, 2026-07-30) Santos, Carlos Vinicius de Paes; Leiva, Daniel Rodrigo; http://lattes.cnpq.br/6576844591900987; http://lattes.cnpq.br/8708708385584665; Leiva, Daniel Rodrigo; Mazzer, Eric Marchezini; Koga, Guilherme Yuuki; Andreani, Gisele Ferreira de Lima; Barros Neto, João Rodrigues de; http://lattes.cnpq.br/6576844591900987; http://lattes.cnpq.br/7273276940567054; http://lattes.cnpq.br/0933095081175012; http://lattes.cnpq.br/9313100199075545; http://lattes.cnpq.br/2493866954666651
One way to enable the use of renewable energy would be to produce hydrogen to act as an energy carrier. However, its storage is a challenge. An alternative would be to store it in a solid state using metal hydrides. Among the hydrides, MgH2 presents excellent gravimetric capacity and cyclability. However, its slow kinetics, associated with operating temperatures >300°C, limit its application. To overcome these limitations, additives are used along with processing techniques. Iron is already employed, showing remarkable performance depending on how it is incorporated. In this research, a magnesium composite with 8% at. Fe was synthesized by rheocasting. The ingot was characterized to verify the iron distribution, and the selected region was processed by manual and rotary filing. Part of the filings was exposed to air; the remainder was ground for 30, 60, and 120 minutes. The materials were characterized by XRD, SEM, DSC, TG, volumetric tests in a Sieverts-type apparatus, and TEM. Fe was heterogeneously distributed throughout the ingot, with the lower region having the highest content (average of ~10.42% wt. Fe). The material containing Fe exhibited superior kinetics and a negligible incubation period when compared to Mg; furthermore, it showed resistance to air exposure. The addition of graphite provided further improvement in kinetics, reaching a transformed fraction of approximately 0.4 in 120 minutes. The apparent activation energy was 160.91 kJ/mol and 135.65 kJ/mol for rotary-processed and manually processed Mg, respectively. For the material containing Fe, the apparent activation energy was 125.91 kJ/mol and 123.88 kJ/mol for rotary-processed and manually processed material, respectively. Therefore, the addition of Fe reduced the apparent activation energy of MgH2 desorption by ~23%.
Movimento lógico-histórico e currículo de Ensino Médio: entre a implementação e a concreticidade
(Universidade Federal de São Carlos, 2026-08-13) Lima, Wilson Francisco da Rocha; Sousa, Maria do Carmo de; http://lattes.cnpq.br/6637658562543505; http://lattes.cnpq.br/3420534562917526; https://orcid.org/0009-0003-0295-1299; Moura, Manoel Oriosvaldo de; Dias, Marisa da Silva; Ciríaco, Klinger Teodoro; Anunciato, Rosa Maria Moraes; http://lattes.cnpq.br/3536854228318246; http://lattes.cnpq.br/4508251745364291; http://lattes.cnpq.br/2947929641568853; http://lattes.cnpq.br/3064136997342775
Following the 2016 coup d’état, the reform of Brazilian upper secondary education was approved through Law No. 13,415/2017. Its implementation began in 2022 and imposed a new organization of pedagogical work, proposing approaches centered on the development of skills and competencies and reducing the workload allocated to areas of theoretical knowledge within the so-called general basic education, while introducing elective curricular units and knowledge pathways that constitute the so-called formative itineraries. In this qualitative doctoral research, grounded in historical-dialectical materialism, we sought to approach an answer to the following question: how can the study of curriculum from the perspective of the logical-historical movement contribute to pedagogical praxis in the context of educational reforms? We therefore established the following specific objectives: to analyze the logical-historical movement of the Brazilian upper secondary education curriculum, identifying the human needs that have historically driven the organization of this educational stage; and to promote a teacher education process from the perspective of the logical-historical movement and analyze participants’ manifestations regarding the New Upper Secondary Education curriculum and their pedagogical practices, seeking to understand the contradictions manifested in the logical-historical movement of the curriculum and in pedagogical praxis. We argue that the curriculum may achieve concreteness insofar as teachers understand its logical-historical movement. The formative actions developed with teachers took place within a public school in the Federal District of Brazil during the first semester of 2024, with the aim of collectively reflecting on the teaching and learning process and the changes required by the New Upper Secondary Education reform. Through records made by the researcher in a journal and transcripts of audio recordings of participants’ statements during the course, we constructed scenes of the phenomenon under study. The analysis of these scenes shows how teachers working within the New Upper Secondary Education framework express their understanding of the new curriculum and of the teaching-learning process, while also providing elements for discussing teacher education from the perspective of the logical-historical movement in the context of curriculum implementation. The results indicate that the contradictions existing within the dialectics of the logical-historical movement of the curriculum, throughout its implementation process, may conceal essential elements of pedagogical activity, leading the educational process, within an atmosphere of regularity and immediacy, toward a state of pseudoconcreteness. In this sense, teacher education organized from the perspective of the logical-historical movement can contribute to the destruction of curricular pseudoconcreteness and to the movement toward concreteness by enabling the apprehension of the contradictions and historical determinations that constitute the curriculum and of the ways in which it is realized in pedagogical activity.