Artigos Científicos - FACFIS/ICEN

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/3216

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Agora exibindo 1 - 19 de 19

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Aprendizagem de eletromagnetismo via programação e computação simbólica
(2002-06) ALVES, Danilo Teixeira; AMARAL, Jair Vaz do; MEDEIROS NETO, João Felipe de; CHEB-TERRAB, Edgardo Salomon
We describe an experience in using programming in Maple as a student's tool for the learning of introductory electromagnetic theory. We believe that this paper can be of use for those interested in using computers as a pedagogical tool.
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The Linear Potential Propagator via Wave Function Expansion
(2002-09) NASSAR, Antônio Boulhosa; BASSALO, José Maria Filardo; ALENCAR, Paulo de Tarso Santos; LOPES, José Luiz Magalhães; OLIVEIRA, José I. F. de; CATTANI, Mauro Sérgio Dorsa
We evaluate the quantum propagator for the motion of a particle in a linear potential via a recently developped formalism [A.B. Nassar et al., Phys. Rev. E56, 1230, (1997)]. In this formalism, the propagator comes about as a type of expansion of the wave function over the space of the initial velocities.
Acesso aberto (Open Access)
Dye incorporation in polyphosphate gels: synthesis and theoretical calculations
(2003-06) DEL NERO, Jordan; GALEMBECK, André; SILVA, Sidicleia Bezerra Costa; SILVA, José Augusto Pereira da
In this work we described theoretical calculations on the electronic structure and optical properties of the dyes crystal violet and malachite green based in semiempirical methods (Parametric Method 3 and Intermediate Neglect of Differential Overlap / Spectroscopic - Configuration Interaction) and the synthesis of a new hybrid material based upon the incorporation of these dyes in an aluminum polyphosphate gel network. The samples are nearly transparent, free-standing thick films. The optical properties of the entrapped dyes are sensitive to chemical changes within the matrix caused either by gel aging or external stimulli such as exposition to acidic and basic vapors that can percolate within the matrix. Our theoretical modeling is in good agreement with the experimental results for the dyes.
Acesso aberto (Open Access)
Modeling of alkynes: synthesis and theoretical properties
(2003-06) ROSSETO, Renato; TORRES, José Celso; DEL NERO, Jordan
In this paper we present the synthesis and simulation of alkynes derivatives. Semiempirical calculations were carried out for the ground and first excited states, including the spectroscopic properties of the absorption and emission (fluorescence and phosphorescence) spectra by INDO/S-CI and DNdM-INDO/S-CI methods with geometries fully optimized by PM3/CI. The fact that the theoretical spectra are in accord with the experimental absorption spectra gives us a new possible approach on how structure modifications could affect the non-linear optical properties of alkynes.
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Wheeler, Tiomno e a Física brasileira
(2003-12) BASSALO, José Maria Filardo; FREIRE JUNIOR, Olival
This paper analyzes the relationships between the American physicist, John Archibald Wheeler, and the Brazilian physicist Jayme Tiomno. It enlarges Tiomno's image as one of the most gifted theoretical physicist of his generation and it reveals that the losses of the Brazilian science, due to the military government (1964-1985), were more meaningful than what one usually admits.
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Electric charge rotating around a black hole
(2005-12) CASTIÑEIRAS RODRÍGUEZ, Jorge; CRISPINO, Luís Carlos Bassalo; FIGUEIRA, Rodrigo Murta de Andrade; MATSAS, George Emanuel Avraam
We consider an electric charge rotating around a Schwarzschild black hole. We compute, using quantum field theory in curved spacetime at the tree level, the power emitted by the rotating charge minimally coupled to the Maxwell field. We also compute how much of the radiation emitted by the swirling charge is absorbed by the black hole.
Acesso aberto (Open Access)
Scalar source in circular motion interacting with massive klein-gordon field in Minkowski spacetime
(2005-12) CRISPINO, Luís Carlos Bassalo; MEIRA FILHO, Damião Pedro
We analyze the scalar radiation emitted by a source in uniform circular motion in Minkowski spacetime interacting with a massive Klein-Gordon field. We assume the source rotating around a central object due to a Newtonian force. By considering the canonical quantization of this field, we use perturbation theory to compute the radiation emitted at the tree level. Regarding the initial state of the field as being the Minkowski vacuum, we compute the emission amplitude for the rotating source, assuming it as being minimally coupled to the massive Klein-Gordon field. We then compute the power emitted by the swirling source as a function of its angular velocity, as measured by asymptotic static observers.
Acesso aberto (Open Access)
Characterization of Buriti (Mauritia flexuosa L.) oil by absorption and emission spectroscopies
(2005-12) ALBUQUERQUE, Marcos Lázaro de Souza; SILVA, Ilde Guedes da; ALCANTARA JUNIOR, Petrus Agrippino de; MOREIRA, Sanclayton Geraldo Carneiro; BARBOSA NETO, Newton Martins; CORRÊA, Daniel Souza; ZILIO, Sérgio Carlos
Oil samples obtained from Buriti (Mauritia flexuosa L.) palm tree fruits were characterized by absorption and emission spectroscopies. The absorption spectrum was recorded in the range from 300 to 2000 nm, while the emission spectrum was analyzed between 400 and 800 nm, where several bands were observed. To better understand these complex spectra, we recorded both absorption and emission spectra of its major components. By correlating these data, we present a discussion on the possible origin of the bands observed.
Acesso aberto (Open Access)
Sir William Thomsom e a instalação do cabo telegráfico submarino entre Pernambuco e o Pará
(2007) BASSALO, José Maria Filardo; CRISPINO, Luís Carlos Bassalo
In this paper we report the participation of Sir William Thomson in the installation of the submarine telegraph cable between Pernambuco and Pará by the Western and Brazilian Telegraph Company in August and September of 1873.
Acesso aberto (Open Access)
Determinação da velocidade e sentido do fluxo de águas subterrâneas utilizando radioisótopos pela técnica do poço único
(2008-06) NERY, José Reinaldo Cardoso; FERREIRA, Leopoldino dos Santos; MOURA, Helyelson Paredes
Radioisotope methodology through the single-well technique have been used with the objective of determining velocity and direction of groundwater flow with radioactive tracers in boreholes located at Universidade Federal do Pará (UFPA), Belém-PA, Brazil, next to Guamá river. We used radiotracer iodine-131 and data was acquired by means of espectrometric system with radiation detectors. The application of this technique to determine jointly velocity and direction of flow, despite not usual, appeared to be a good alternative for further practical applications.
Acesso aberto (Open Access)
Análise de metodologia baseada no sistema de ensino individualizado de Keller aplicada em um curso introdutório de eletromagnetismo
(2011-03) ALVES, Danilo Teixeira; SOUZA, Sandro Aléssio Vidal de; PEREIRA FILHO, Silvio Carlos Ferreira; ELIAS, Walace de Sousa
One of individualized teaching methods used and documented in the 70's was Fred Keller's Personalized System of Instruction (PSI). Several papers about this methodology were published, providing an extensive empirical evidence of PSI's positive results. Nonetheless its employment has declined staring in the 80's. Among the reasons for this decline, we may emphasize the greater effort required to the development of such courses using this methodology as compared to other methodologies and the provisioning of a systematic feedback on students' performance, as well as the criticisms on Keller's behaviorist approach. Despite being critical to learning, the stimulus to student's active posture, respect for individual learning rhythm, the formative assessments and the provisioning of systematic feedback to students still take place outside the classroom. One strategy to counter such deficiencies is individualized instruction. In this paper, we propose several modifications to Keller's SPI seeking a feasible methodology to be applied in an introductory course of electromagnetism for students of Physics of Universidade Federal do Pará. Among these modifications, we highlight: (i) the use of weekly assessments, but not in every lecture; (ii) the correction of assessments and feedback providing made by teachers and not teaching assistants; and (iii) the partial maintenance of the expositive classes. Despite the modifications inserted, based on an evaluation which included measurable benchmarks, we have indications that the application of this methodology yielded several of those positive results common to the implementation of Keller's SPI.
Acesso aberto (Open Access)
Inversion method for obtaining electrical parameters for soil in the rural region in Brazil
(2015-06) OLIVEIRA, Rômulo Augusto Nascimento de; MAGNO, Fátima Nazaré Baraúna; SOUZA, João Furtado de; COZZOLINO, Klaus; CAVALCANTE, Gervásio Protásio dos Santos
This paper presents an inversion methodology through weighted least squares to obtain the electrical parameters for the soil of a typical mid-western region in Brazil using the model based in the formalism of the parabolic equations to calculate the electric field intensity received. To validate this methodology, the results of the radio signal measurement campaign conducted in six radial routes leaving the city of Brasilia, Federal District, where the transmitter was located, were used. The measurements were compared to computer simulations and, thus, the optimal values for the electric conductivity and relative permittivity for the soil of the region could be estimated. Finally, a quantitative analysis of these parameters was performed with the values found in the literature, which demonstrated the effectiveness of the proposed methodology.
Acesso aberto (Open Access)
Medindo a velocidade do som utilizando figuras de Lissajous
(Universidade Federal do Pará, 2015-09) MAGNO, Fátima Nazaré Baraúna; SOUZA, João Furtado de; PEREZ, Silvana
There are several techniques to obtain the sound velocity in air, from the very simple ones, which use the relation between distances and time, until the more sophisticated ones, associated with oscillatory phenomena. In this work we propose an experimental aparathus which involves the Lissajous figures and ressonance tubes. The physical phenomena that appear in the process allow the student to observe and understand several ondulatory processes, as well as the superposition principle and can be applied to engenier and physics undergraduate students.
Acesso aberto (Open Access)
Cálculo de velocidades em acidentes de trânsito: um software para investigação em física forense
(Universidade Federal do Pará, 2015-12) GURGEL, Walldiney Pedra; GOMES, Luiz Moreira; FERREIRA, Fernanda Carla Lima; GESTER, Rodrigo do Monte
In this paper we present and evaluate the Speed Calculations software for Traffic Accidents (SCTA). This application is designed for forensic studies and follows a protocol that allows the expert in crime scene analysis, even one that has no knowledge of physics, to estimate vehicle speeds involved in collisions and pedestrian accidents. SCTA uses basic concepts of classical mechanics, employs different coefficients of friction and takes into account the damage and the characteristics of the vehicles involved. This allows to determine the speeds in various accident situations. The software follows an open source philosophy, allowing implementation of new accident scenarios. Finally, as input data, SCTA needs only a few measurements performed by an expert. This avoids unnecessary scene observation and, optimizes and ensures reliability of forensic expertise.
Acesso aberto (Open Access)
Explorando história da ciência na Amazônia: o Museu Interativo da Física
(Universidade Federal do Pará, 2016-08) CALDAS, Jocasta; LIMA, Marcelo Costa de; CRISPINO, Luís Carlos Bassalo
In 2008, professors and students of the Physics Department of the Federal University of Pará realized a pioneering initiative for the dissemination of the History of Science in the Brazilian Amazonia. This initiative, named Physics Interactive Museum, started to act in partnership with the Amazonian community, its governmental organizations, other universities, state and municipal schools of the Pará State aiming to collaborate with the enhancement of the quality of science education in the region. We present the activities of the Physics Interactive Museum and the impact of its participation in the dissemination of History of Science in the Brazilian Amazonia.
Acesso aberto (Open Access)
Divulgação científica na Amazônia: o laboratório de demonstrações da UFPA
(Universidade Federal do Pará, 2017-01) CALDAS, Jocasta; CRISPINO, Luís Carlos Bassalo
Science communication has a key role in democratizing the access to knowledge. In the last decades, many scientific diffusion initiatives emerged and developed in a process of expansion of institutions and investments. In the Brazilian Amazonia, the number of science communication actions is far less than what would be necessary to satisfactorily contemplate its vast territorial extension. The Demonstrations Laboratory of the Federal University of Pará, founded in 2004, has acted as a science center aiming the advancement of scientific literacy in the Brazilian Amazonia, as well as the dissemination and popularization of science and technology. We present the activities of this Demonstrations Laboratory over more than a decade of operation and the impact of its educational and science communication actions carried out in the Brazilian Amazonia.
Acesso aberto (Open Access)
Sobre a representação mecânica das forças elétrica, magnética e galvânica, de William Thomson: uma leitura comentada
(Universidade Federal do Pará, 2017-03) LIMA, Marcelo Costa de; COSTA, R. S.
We present and comment the homonimous article originally published by William Thomson, in 1847, in which the author explores the analogy between the estates of deformation in an elastic solid and the configurations of Faraday's lines of force. In this article Thomson has introduced for the first time the magnetic potential vector, associated in this context with rotational deformations in the solid. We present as well, the historical context in which Thomson's original paper has been conceived.
Acesso aberto (Open Access)
Expedição norte-americana e iconografia inédita de Sobral em 1919
(Universidade Federal do Pará, 2017-06) CRISPINO, Luís Carlos Bassalo; LIMA, Marcelo Costa de
We report on the observations in Brazil related to the total solar eclipse of May 29th, 1919, giving emphasis to the less known expedition organized by the Carnegie Institution, leaded in Brazil by the American Daniel Maynard Wise. We exhibit a selection of unpublished photographies obtained by Wise during his stay in Brazil.
Acesso aberto (Open Access)
O estudo do movimento browniano com material de baixo custo
(Universidade Federal do Pará, 2017-07) PEREZ, Silvana; MAIA, Noel das Chagas; NASCIMENTO, Cristovão Silva; CASTRO, Bárbara Fernandes do Nascimento
The study of Brownian motion is seen in modern physics disciplines of undergraduate courses in physics, following a theoretical or laboratory approach, in this case usually involving reasonably sophisticated equipment. This work describes a proposal for the implementation of the experiment in high school, designed and developed by students of the last semester of the night course of licentiate in Physics of the Federal University of Para, as part of the activities of a discipline of Statistical Physics. The ease of assembly of the experiment, combined with the use of computational technologies to analyze the results, makes the technique easily implemented in high school, enabling the student to discuss historical aspects of the development of atomic models, as well as to perform the experimental measurement of the number of Avogrado, usually seen in Chemistry, in a mechanized way.

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