Navegando por Assunto "Statistical analysis"

Agora exibindo 1 - 3 de 3

Acesso aberto (Open Access)
Análise de propagação de ondas eletromagnéticas na faixa de microondas em ambiente indoor com método 3D FDTD e FDTD 2D modificado
(Universidade Federal do Pará, 2012-03-08) RIBEIRO, Dionisio Raony de Souza; DMITRIEV, Victor Alexandrovich; http://lattes.cnpq.br/3139536479960191
This work presents tools of low computing cost and good accuracy to characterize the electromagnetic microwave propagation in indoor environments. It was studied the Finite- Difference Time-Domain (FDTD) method applied to model the propagation in these environments. The study deals with the implementing of a new approach of this method which converses a 3D problem in a 2D one. It is presented a comparative study between the two formulation of the method regarding accuracy, speed and the requirement of computing resources. To apply the 3D formulation, a software was written in FORTRAN with the FDTD 3D parallelized by the MPI library. Then, a cluster with Beowulf architecture was set up run the routine. After the validation of the modified FDTD method, it is applied to characterize an indoor environment regarding its losses. This data was used to obtain the statistical distribution of the parameter n of propagation loss of the environment. The contribution of this work lays on the fact that the researched literature do not present the modified FDTD 2D method applied to indoor environments and the use of simulated data to statistical analysis.
Acesso aberto (Open Access)
Avaliação de parâmetros da qualidade do ar em um município amazônico do Estado do Pará
(Universidade Federal do Pará, 2025-02-21) ROSÁRIO, Abimael Silva do; MENDONÇA, Neyson Martins; http://lattes.cnpq.br/7534816053779593
This study evaluated the air quality in Barcarena, Pará, Brazil, throughout 2023, focusing on monitoring particulate matter concentrations (PM2.5, PM10, and TSP) at two points (P01 and P02) near an industrial complex with activities such as ore beneficiation and shipment, agricultural fertilizer storage and bagging, and grain shipment. These points were strategically chosen due to their location within the influence zone of various enterprises and the prevailing wind direction in the region. Samples were collected using High-Volume Samplers (HVS) over 24-hour periods, following guidelines from the Air Quality Technical Guide and CONAMA Resolution No. 491/2018. Collected data underwent descriptive and multivariate statistical analysis using Minitab Statistical software to determine PM2.5, PM10, and TSP concentrations and calculate the Air Quality Index (AQI). Results showed PM2.5, PM10, and TSP concentrations complied with the intermediate standards (PI-1) of CONAMA Resolution No. 491/2018 and the stricter limits of CONAMA Resolution No. 506/2024. The AQI for PM2.5 and PM10 was classified as "N1 - Good" throughout the study period, indicating no harmful effects on human health. Additionally, the study conducted a cost analysis of air quality monitoring campaigns, considering supplies, labor, and equipment, using ORÇAFASCIO software for budget development. This study contributes to air quality monitoring in areas with intense industrial activity, providing relevant data for environmental management and public health. Furthermore, the cost analysis offers valuable insights for planning and decision-making in similar projects.
Acesso aberto (Open Access)
Mapeamento geoquímico por sedimentos de corrente da bacia hidrográfica do Rio Capim-Pa: definição de valores de baseline geoquímico e aplicação de índices ambientais
(Universidade Federal do Pará, 2025-01-16) SERRA, Julio Richard Furtado; MARQUES, Eduardo Duarte; http://lattes.cnpq.br/8256609331887637; HTTPS://ORCID.ORG/0000-0003-1133-9408; KÜTTER, Vinicius Tavares; http://lattes.cnpq.br/6652786694334612; https://orcid.org/0000-0001-7295-6800
Geochemical mapping plays a key role in both mineral prospecting and environmental studies. Initially used to identify geochemical anomalies associated with mineral deposits, these studies have gained relevance in the field of environmental geochemistry, enabling the monitoring of soil, water, and sediment quality. The Geological Survey of Brazil (SGB) conducts geochemical survey projects across the national territory. One such project, carried out between 2009 and 2012, called "Multi-use Geochemistry," covered the Capim River Watershed (CRW) area and generated a geochemical sediment dataset for the region. The objective of this research was to use this available data to create multielemental geochemical maps and define baseline geochemical values, particularly for potentially toxic elements. The survey included the collection of 276 stream sediment samples with a sampling density of approximately one sample every 150 km². The samples were processed in the laboratory for analysis by ICP-OES and ICP-MS with hydride generation for Hg. In total, 52 elements were analyzed (Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Ge, Hf, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pd, Pb, Pt, Rb, Re, S, Sb, Sc, Se, Sn, Sr, Ta, Te, Th, Ti, U, V, W, Y, Zn, and Zr). For statistical treatment, statistical summaries were calculated along with box plots, histograms, and normal probability curves using log-transformed data for univariate statistics; Spearman correlation for bivariate statistics; and factor analysis (FA) to define multielemental associations in multivariate statistics. Three methods were applied to calculate the geochemical baseline (BG), including the Median ± 2*Median Absolute Deviation (mMAD), Tukey's Inner Fence (TIF), and Percentiles (98, 95, 90, 75). The results revealed important geochemical distribution trends, with a particular focus on potentially toxic elements. In total, 28 elements (Ag, Al, Ba, Bi, Ce, Co, Cr, Cu, Fe, Ga, Hf, Hg, La, Mo, Nb, Ni, Pb, Rb, Sc, Sn, Sr, Th, Ti, U, V, Y, Zn, and Zr) underwent more complex statistical tests, while 24 elements were not tested due to ≥30% of the data being below the detection limit. Correlation analyses showed that there were 7 correlations with significance values greater than 0.65 and 6 acceptable correlations with values between 0.575 and 0.65. It was observed that Cr levels exceeded the values stipulated by the resolution in all three methods analyzed: TIF (73.11 mg.kg⁻¹), mMAD (46.76 mg.kg⁻¹), and 98th Percentile (43.00 mg.kg⁻¹). In the lithological unit analysis, Cr anomalies were most pronounced for the siliciclastic rocks of the Barreiras Formation, with TIF (182.94 mg.kg⁻¹), mMAD (90.88 mg.kg⁻¹), and Percentiles 98th (66.28 mg.kg⁻¹), 95th (62.20 mg.kg⁻¹), 90th (52.60 mg.kg⁻¹), and 75th (40.52 mg.kg⁻¹), as well as in Lateritic Covers with TIF (81.76 mg.kg⁻¹) and mMAD (46.49 mg.kg⁻¹). The mMAD method was considered the most conservative and robust, without overestimating the upper limit values. Factor analysis allowed the identification of 7 factors, and along with the spatial mapping of the scores, it was possible to identify the geochemical associations, which primarily reflect the geological influence in these sediments, with lateritic terrains, iron oxyhydroxides, and aluminossilicatic clastic rocks being the main factors responsible for the distribution of the elements. Geochemical and environmental indices were calculated, such as the Enrichment Factor, Contamination Factor, Modified Contamination Degree, and Potential Ecological Risk Index. These indices indicated that, in several microbasins, there are signs of geological sources, but they mainly point to the northern, western, and southwestern areas of the CRW as the most contaminated. These approaches enabled the identification of contaminated areas, especially related to Cr, Cu, Hg, Ni, and Pb, whose concentrations exceeded the limits established by CONAMA Resolution 454/2012 at several points in the basin. However, it is worth noting that the normative uses reference values for total sediment, and the results of the present work are overestimated compared to this standard. Nevertheless, the use of environmental indices must be done with caution, as there are limitations that, when analyzed in isolation, may provide information not entirely aligned with local reality, either overestimating or underestimating data. It is important to highlight that, despite presenting higher concentrations of these elements, the values found are still lower than those found in geochemical provinces with mineralizations. This indicates a strong influence of superficial geochemical processes in the adsorption of Cr, Cu, Ni, and other potentially toxic metals in iron oxyhydroxides. Furthermore, the study reaffirms the use of the mMAD method as the most robust and suitable for defining baselines and the use of geochemical distribution maps as an essential tool for territorial management.