Navegando por Assunto "Processamento de dados"

Agora exibindo 1 - 6 de 6

Acesso aberto (Open Access)
Análise de parâmetros da função característica de Hamilton
(Universidade Federal do Pará, 1998) TAVARES, Isabel Cristina; SÖLLNER, Walter Franz
The velocity analysis is a fundamental process in reflexion seismic, where the stacking velocity as well the zero offset traveltime are sufficient for determining the geological model for media with flat layers. On the other hand the Hamilton formalism uses the same parameters (velocity and zero offset traveltime) for determining the characteristic function for that kind of model. For a three-dimensional heterogeneous geological model with arbitrarily curved surfaces, the characteristic function is defined by nine parameters. This thesis aims at determining the characteristic function through the analysis of parameters using times slices in traveltime function, both in the CMP and zero offset ensemble. This analysis is done by the observation the behavior of each parameters during the fitting between the calculated characteristic function and the traveltime function obtained from the data survey.
Acesso aberto (Open Access)
Aplicabilidade de um sistema de baixo custo para o monitoramento de dados meteoceanográficos na zona costeira Amazônica
(Universidade Federal do Pará, 2025-04-23) SOTÃO, Daniel da Silva; ROSÁRIO, Renan Peixoto; http://lattes.cnpq.br/8003860457518342; https://orcid.org/0000-0003-2913-0514
This study aimed to develop, implement, and validate a low-cost Continuous Monitoring Prototype (CMP) to collect meteoceanographic data in the Amazon Coastal Zone (ACZ), a region vulnerable to climate change and lacking environmental data. The system, built with an ESP32 microcontroller, integrates sensors for air temperature and relative humidity (HDC1080 and AM2302), atmospheric pressure (BMP280 and MS5611), water temperature (DS18B20), tide level (HC-SR04), precipitation, and wind speed and direction. Sensor validation was performed by comparing the collected data with reference equipment: a CICLUS PRO weather station (CWS) and a Sonlist Levelogger 5 LTC recorder (CTDlog). The CMP conducted four joint test campaigns with the CWS and CTDlog, totaling 56,221 records. Linear regression was applied to develop calibration equations for each sensor. Calibration quality was assessed using the coefficient of determination (R²), root mean square error (RMSE), Pearson correlation coefficient, and residual analysis. The HDC1080 and AM2302 sensors showed excellent performance for temperature measurement, with R² > 0.9, RMSE < 0.2 °C, mean absolute residual (MAE) < 0.12 °C, and very strong Pearson correlation (r ≥ 0.9). However, they exhibited instability in relative humidity measurements (R² ≈ 0.64; RMSE ≈ 3.46%; MAE ≈ 2.52%). The performance of the BMP280 and MS5611 pressure sensors was initially affected by internal heating, but after thermal compensation, they achieved R² values between 0.88 and 0.99, RMSE from 0.17 to 0.45 hPa, and MAE from 0.11 to 0.34 hPa, with the BMP280 showing superior performance. The DS18B20 water temperature sensor showed very strong correlation, with R² ≈ 0.94, RMSE ≈ 0.036 °C, and MAE ≈ 0.021 °C, proving highly promising. The HCSR04 sensor stood out as the most accurate, with R² ≈ 0.99, RMSE ≈ 2.6 cm, and MAE ≈ 1.9 cm. Precipitation and wind sensors presented inconsistencies and require further testing. The total production cost of the CMP was BRL 952.75, representing savings of 86.19% compared to the CWS (BRL 6,897.00) and 96.14% compared to the CTDlog (BRL 24,677.29). When compared to equivalent equipment, the CMP achieved at least 66.33% cost reduction compared to basic stations and 87.3% compared to lower-cost temperature and water level recorders. The CMP proved to be a viable, economical, and replicable solution for continuous environmental monitoring in the ACZ, with the potential to fill existing gaps in observation networks, although improvements are still needed to enhance its long-term performance.
Acesso aberto (Open Access)
Detecção de refletores sísmicos por rede neural discreta
(Universidade Federal do Pará, 1999) FERREIRA, Alexandre Beltrão; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926; LEITE, Lourenildo Williame Barbosa; http://lattes.cnpq.br/8588738536047617
The artificial neural networks have proven to be a powerful technique in solving a wide variety of optimization problems. In this work, we develop a new recurrent network, with no self-feedback loops, and no hidden neurons, for seismic signal processing, where this neural network gives the true polarity, reflectors location and magnitude estimations. The main characteristic of this neural network is the use of a type of activation function which permits three possible states of neurons, to estimate the position of the seismic reflectors in such way to reproduce its true polarities. The basic idea of this new neural network type, denominated here by discrete neural network (DNN), is to relate a cost function, that describes the geophysical problem, with the Liapunov function, that describes the neural network dynamics. In this way, the dynamics of the network leads to a local minimization of the Liapunov function, and will consequently lead to a minimization of the cost function. Thus, with a convenient output signal codification of the neural network a geophysical problem solution is obtained. The operational evaluation of this neural network architecture is performed with synthetic data obtained through the simple convolutional model and seismic ray theory, and its behavior explained with additive noise in the data with minimum, maximum and mixed phase time source pulses.
Acesso aberto (Open Access)
Marcação e atenuação de múltiplas de superfície livre, processamento e imageamento em dados sísmicos marinhos
(Universidade Federal do Pará, 2012) CARNEIRO, Raimundo Nonato Colares; LEITE, Lourenildo Williame Barbosa; http://lattes.cnpq.br/8588738536047617
The present research aimed to the analysis and mitigation of multiple free surface, processing and imaging of marine seismic data to obtain useful images migrated to the geological interpretation focused on oil exploration. Attention has been paid to the systematic study of multiple unobstructed view of the prediction filter based on the theory of communication in order to better apply the filter deconvolution WH predictive, in processing stage subsequent to the NMO correction, although other methods may be considered as competitive. The identification and attenuation of multiple reflections in real seismic data remains a major challenge in seismic data processing, since they are considered as noise. However, this noise being classified as coherent, several techniques have been developed aiming at mitigation to avoid cascading errors in the later stages such as processing, scheduling events, tomographic inversion, imaging, and finally the geological interpretation of the images obtained. Another aspect in this study was to establish a flowchart of processing, imaging and attenuation of multiple free surface of a central step. Migrated sections were obtained in time and depth where it allows the interpretation. The development of this research was preformed with CWP/SU and MatLab packages.
Acesso aberto (Open Access)
Melhoramento da resolução para camadas delgadas de perfilagens existentes em áreas específicas de produção-exploração
(Universidade Federal do Pará, 1990-11-28) AIZMAN, Luiz; EVANS, Hilton Bernard
In well Iogging, there is a great interest in techniques that enhance the vertical resolution of the tool responses. In this work we develop a technique that enhances the vertical resolution of the logs obtained with the induction logging tool named in the bibliography 6FF40, by means of an algorithm that makes use of estimative methods through the least square technique. This method makes possible the processing of a set of recorded data in a computationaly efficient way. This algorithm requires only the values assumed as tool coeficients and an estimative for the noise present in the recorded data. As an ilustration we used intervals of a log run in an area where the 6FF40 tool is known to have poor vertical resolution. In order to verify the efficiency of the used algorithm, the processed logs were correlated with the gamma-ray and with the spherically focused log of the well 7-LOR-18-RN, which have a better vertical resolution, confirming the enhanced resolution in thin layers that could not be easily recognized on the previously log. The algorithm was also tested with synthetic data demonstrating its efficiency in calculating more representative values for Rt.
Acesso aberto (Open Access)
Um software de reconhecimento de voz para português brasileiro
(Universidade Federal do Pará, 2010-06-17) SILVA, Carlos Patrick Alves da; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
This work describes a speech recognition software for Brazilian Portuguese. The main objective is to build a system for large vocabulary continuous speech recognition, able to be used in real-time applications. The concepts, characteristics and all steps needed for the construction of such systems are presented. Several resources were produced and made available: acoustic and language models, new voice and text corpora. The text corpus has been built through the extraction and automatic formatting of text from newspapers on the Internet. In addition, two voice corpora were produced, one based on audiobooks and another specifically developed to simulate real-time tests. This work also proposes the use of speaker adaptation techniques for solving the acoustic mismatch problem between speech corpora. Finally, an application programming interface is presented in order to facilitate using the open-source Julius speech decoder. Performance tests are also presented, comparing the developed system with a commercial software.