Principais Coleções do Repositório
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dissertação
Dissulfeto de dialila no controle de Meloidogyne incognita em alface e (R)-carvona no manejo de plantas daninhas.
(Universidade Federal de Lavras, 2026-07-24) Correia, João Paulo; Oliveira, Denilson Ferreira de; https://orcid.org/0000-0001-9326-8716; Terra, Willian César; https://orcid.org/0000-0002-7683-6790; Salgado, Sônia Maria de Lima; https://orcid.org/0000-0003-0306-1725; Moreira, Silvino Intra; https://orcid.org/0000-0003-4693-8806
Lettuce (Lactuca sativa L.) is a vegetable crop of considerable socioeconomic importance in Brazilian agriculture. However, its production faces significant challenges, particularly damage caused by plant-parasitic nematodes, specifically Meloidogyne incognita, and competition from weeds. Given the absence of registered chemical nematicides for lettuce and the need to reduce dependence on conventional synthetic inputs, this study evaluated the efficacy of compounds derived from Allium sativum (diallyl disulfide, DADS) and Menthaspp. (R)-carvone) as alternative management strategies. The experiments were conducted at the Center for Development and Technology Transfer (CDTT/UFLA), located in Ijaci, Minas Gerais, Brazil. A randomized complete block design was adopted, consisting of four treatments with six replicates: diallyl disulfide (DADS), (R)-carvone, an untreated control (water), and a commercial metam sodium-based product. Evaluations were performed 45 days after treatment application and included the number of M. incognita eggs per gram of root, as well as the fresh biomass of shoots and roots. For weed assessment, soil samples were collected from the experimental plots, homogenized, and placed under greenhouse conditions for subsequent species identification and analysis of diversity indices (ShannonWiener, Richness, and Evenness). The results demonstrated that DADS exhibited nematicidal activity, significantly reducing the number of eggs per gram of root (by 48% to 65%), with performance statistically comparable to that of the commercial product. In contrast, (R)-carvone did not provide significant nematode control, remaining statistically similar to the untreated control. Regarding plant growth parameters, metam sodium promoted the greatest increases in shoot and root fresh biomass. Although DADS and (R)-carvone produced intermediate results, both significantly outperformed the untreated control. In weed management, metam sodium inhibited seed germination by more than 99% and significantly reduced all diversity indices. (R)-Carvone reduced weed germination by 71.36%, whereas DADS achieved a 43.65% reduction, without significantly altering the diversity of the weed community relative to the untreated control. These findings indicate that DADS represents a promising alternative for the management of M. incognita, while (R)-carvone stands out for its high herbicidal potential, supporting the use of plant-derived compounds as sustainable tools for the integrated management of lettuce crops.
dissertação
Discurso da violência contra as mulheres: uma análise de processos enunciativos em posts do Instagram
(Universidade Federal de Lavras, 2026-06-30) Santos, Angelita Pereira dos; Cano, Márcio Rogério de Oliveira; https://orcid.org/0000-0001-5502-6951; Silva, Luciana Soares da; https://orcid.org/0000-0001-5145-8503; Santos, Záira Bomfante dos; https://orcid.org/0000-0002-6162-8489
During the transition from the feudal system to capitalism in Europe, as well as in the structuring of society in colonial and imperial Brazil, it is evident that women’s history was marked by various types of violence. These women’s lives were governed by the imposition of the patriarchal system, the state, and the Church, which dictated norms of behavior and control over the body. In the current context, women still face various forms of violence. In this regard, the focus of this research is the discourse of violence against women present on social media, specifically on Instagram. The general objective is to analyze the process by which the discourse on violence against women is constructed, examining the representations of the work of subalternized and privileged groups produced on social media, specifically in Instagram posts. Our specific objectives are: (1) to analyze the subject that emerges in the enunciation of the discourse on violence against women and (2) to study the historicity that shapes the effects of meaning in this discourse. Regarding the theoretical framework, our research draws on the studies by Orlandi (2005), Courtine (2009), and Pêcheux (1995) on Discourse Analysis to understand the notions of the subject, the socio-historical conditions of discourse production, and their relationship with utterances in terms of meaning and historicity. Furthermore, it engages with studies in the Humanities: Federici (2023), Del Priore (2014; 2020), Lélia Gonzalez (2020), Gramsci (2024), Spivak (2010), Bourdieu (2012), among others. The methodology draws on the theoretical and methodological contributions specific to Discourse Analysis, from which we utilize the categories of subject and historicity to analyze our corpus. The analyses indicate that the statements evoke different subjects and historicity in a discourse of violence against women when it comes to representations of the labor of subalternized and privileged groups.
dissertação
Uso de aprendizagem de máquina e otimização multiobjetivo para estimar energia potencial de aerogeradores
(Universidade Federal de Lavras, 2026-07-13) Brito, Durval Camargo Rangel de Souza; Barbosa, Bruno Henrique Groenner; https://orcid.org/0000-0002-7579-5763; Lacerda, Wilian Soares; https://orcid.org/0000-0001-8378-9745; Ferreira, Silvia Costa; https://orcid.org/0000-0002-3454-8862; Santos, Caio dos; https://orcid.org/0000-0002-3423-6690
The global energy transition has driven the growth of wind energy, particularly in Brazil, where it accounts for 12.8% of the national electricity mix. The efficient operation of wind farms requires sophisticated strategies to maximize energy extraction, given the inherent intermittency of the wind resource and the operational challenges of field environments. This work proposes an artificial-intelligence-based methodology for estimating the potential energy of wind turbines, using exclusively meteorological data from met masts and operational data from SCADA systems. The approach integrates multimodal data filtering and multi-objective optimization via NSGA-II for the simultaneous selection of data sources, meteorological variables, and machine learning model hyperparameters, exploring the trade-off between predictive accuracy and operational complexity. The methodology was validated on two GE 2.5 MW wind turbines located in Xique-Xique, Bahia, under distinct operational conditions: W301, operating under relatively free-stream wind, and W310, subject to pronounced wake effects. The dataset comprises 31 SCADA variables and meteorological measurements from 8 nearby met masts, totaling 51,564 samples collected between January 2024 and January 2025. Data filtering yielded 65% of usable samples for W301 and 63.5% for W310, removing periods of shutdowns, curtailments, and degraded operation. The NSGA-II algorithm revealed a consistent geospatial hierarchy in source selection, autonomously converging to three-met-mast configurations covering inflow conditions, intermediate flow evolution, and local conditions near the target turbine. For W301, optimized models achieved R 2 of 0.984 (XGBoost) and 0.982 (MLP), compared to 0.973 for the reference model. For W310, gains were even more expressive, with R 2 of 0.973 and 0.972 against 0.933 for the baseline, demonstrating that the methodology delivers proportionally greater value under complex operational conditions. Applying the final models to the complete historical dataset enabled estimation of energy losses between 4.7% and 6.5% of the available potential, with direct implications for maintenance planning and contractual negotiations. The proposed approach overcomes limitations of traditional methods based on IEC 61400-12-1, providing estimates of the true physical potential of the turbine without embedding operational restrictions as normal behavior.
tese
Parametrização das operações de filtração e retrolavagem de um filtro de areia comercial
(Universidade Federal de Lavras, 2026-03-06) Passos, Mádilo Lages Vieira; Freire, Evelise Roman Corbalan Gois; https://orcid.org0000-0003-0245-6055; Deus, Fábio Ponciano de; https://orcid.org/0000-0003-2495-1612; Baptista, Victor Buono da Silva; https://orcid.org/0000-0002-5355-5427; Oliveira, Luiz Fernando Coutinho de; https://orcid.org/0000-0001-5260-3258; Ribeiro, Maycon Diego; https://orcid.org/00000-0002-9311-5944; Barbosa, Eduardo Augusto Agnellos; https://orcid.org/00000-0002-1393-4166
The sand filter has two independent but complementary modes of operation, known as filtration and backwashing. Studies show that a range of factors interfere with these operations, making correct use of the equipment difficult. Thus, divided into two general parts, this research addresses technical and scientific aspects regarding the definition of filtration and backwash parameters for a Hidrosolo commercial sand filter model FA07. The first part presents a general introduction to the topic under study with the objectives and hypotheses. The second part consists of three scientific articles. In the first article, the objective was to use artificial neural networks to model pressure loss and filtration removal efficiency. Experimental tests covered three grain sizes of silica sand (fine, medium, and coarse) and four filtration rates (20, 40, 60, and 75 m h⁻¹). Three artificial neural networks (ANN1, ANN2, and ANN3) were built to define the duration of the filtration cycle, the pressure loss, and the filtered volume. ANN1 was based on modeling the pressure loss through the filter, while ANN2 and ANN3 were based on suspended solids in the effluent. The variables used were the filtration rate, the filtered volume, grain size, suspended solids, and pressure loss. ANN1 performed well with a 5-4-1 architecture. Increasing the filtration rate reduced the duration of the filtration cycle, while increasing grain size prolonged it. Networks ANN2 and ANN3 performed unsatisfactorily and were therefore discarded. In the second article, the objective was to evaluate the influence of the drainage system’s constructive design on the hydraulic behavior of the backwash process. Two filter bed heights were used (0.15 and 0.30 m) and three drain models: cylindrical drain — corresponding to the manufacturer’s original model; conical; and a proposed drain — corresponding to the result of development using computational fluid dynamics. Bed expansion was similar between the original and proposed drains for both bed heights. The greatest bed expansion efficiency was observed for the conical drain at the 0.15 m height. The proposed drain showed lower pressure loss with an empty filter, but values were similar when filled with sand. The minimum fluidization velocity was the same for the original and proposed drains (18.0 m h–1 ), and higher for the conical drain (24.0 m h–1 ). In the third article, the aim was to evaluate the influence of the drainage system's constructive design, the backwash duration, and the expansion of the filter layer on the layer's cleaning efficiency. Two levels of filter bed expansion (25% and 50%), three backwash durations (three, eight, and fifteen minutes), and two drainage system designs were evaluated: 1) cylindrical drain; and 2) proposed drain. The proposed drain model outperformed the original model, especially at 25% expansion. Overall, 50% expansion provided better performance for both drain models, with the proposed drain standing out. Cleaning efficiency was lower in regions near the filter walls, regardless of the drain model, the layer expansion level, or the backwash duration. In general, there was a trend of increased total bed cleaning efficiency with longer backwash duration. The turbidity behavior of the backwash water showed that the greatest variation occurs in the first minutes of the backwash, indicating that most solids are removed at the beginning of the process. Finally, the proposed drain had lower water and energy consumption, with higher efficiency rates compared to the commercial model
dissertação
Marcadores moleculares aplicados à certificação de cruzamentos, análise de pureza varietal e resistência à ferrugem em cafeeiro
(Universidade Federal de Lavras, 2026-03-26) Zaldivar, Norma Edith Zelaya; Gonçálves, Flávia Maria Avelar; https://orcid.org/0000-0003-4652-1824; Souza, Lucimara Cruz de; https://orcid.org/0000-0001-5795-7960; Silva Júnior, Adelson Lemes da; https://orcid.org/0000-0003-0940-8398; Botelho, César Elias; https://orcid.org/0000-0001-6143-9875; Gonçalves, Flávia Maria Avela; https://orcid.org/0000-0003-4652-1824; Souza, Lucimara Cruz de; https://orcid.org/0000-0001-5795-7960
The genetic improvement of Coffea arabica through controlled hybridizations constitutes a fundamental strategy for the development of cultivars with superior agronomic traits. In this context, the verification of varietal purity of parental lines and the certification of molecular markers stands out as an efficient tool for these purposes, enabling the genetic validation of genotypes. In addition, marker-assisted selection (MAS) has been widely employed to accelerate the incorporation of resistance genes, especially against coffee leaf rust, caused by Hemileia vastatrix. This study was divided into two articles, whose objectives were to validate varietal purity and certify crosses among C. arabica cultivars, as well as to select resistant plants using molecular markers. In the article, genomic DNA was extracted from 11 parental lines and their F1 hybrids using the CTAB (cetyltrimethylammonium bromide) method, with modifications. Initially, 31 SSR (Simple Sequence Repeat) markers and five SCAR (Sequence Characterized Amplified Region) markers were screened to evaluate polymorphism among the parental lines of each cross. The primers CaEST-002, CaEST-029, CaEST-071, CaEST’-072, AJ254, SSRCa87, CM101, CaRHv10, and S235 demonstrated discriminatory capacity to differentiate molecular profiles among the parental lines of three crosses and were selected for subsequent analyses. Subsequently, to certify varietal purity, plants from each parental line were compared with previously characterized coffee plants of known genetic identity. Plants resulting from varietal mixture or contamination were identified in five of the evaluated parental lines and were discarded from further analyses. Cross certification was performed for the parental combinations Catiguá MG2’ (G12) × ‘Topázio MG1190’ (G3), ‘Villa Sarchi’ (G22) × ‘MGS Paraíso 2’ (G9), and ‘Sarchimor 8840’ (G10) × ‘IPR100’ (G6). Seventeen hybrids and one self-fertilized plant were identified in the cross between G12 x G3. In the second article, marker-assisted selection (MAS), linked to a QTL located on linkage group 2 (LG2) of C. arabica, associated with resistance to races I and II, and pathotype 001 of H. vastatrix. Through this analysis, 23 homozygous resistant plants and 15 heterozygous plants were identified and considered in the selection, as they carried the resistance allele. The results obtained in this study highlight the importance of integrating molecular tools into coffee breeding. Certification ensured the genetic identity of the populations obtained, guaranteeing reliability in generation advancement. In parallel, MAS enabled the early identification of plants carrying resistance alleles, increasing the efficiency of the selection process