10 resultados para Empirical Mode Decomposition, vibration-based analysis, damage detection, signal decomposition

em Universidade Federal do Rio Grande do Norte(UFRN)


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The seismic processing technique has the main objective to provide adequate picture of geological structures from subsurface of sedimentary basins. Among the key steps of this process is the enhancement of seismic reflections by filtering unwanted signals, called seismic noise, the improvement of signals of interest and the application of imaging procedures. The seismic noise may appear random or coherent. This dissertation will present a technique to attenuate coherent noise, such as ground roll and multiple reflections, based on Empirical Mode Decomposition method. This method will be applied to decompose the seismic trace into Intrinsic Mode Functions. These functions have the properties of being symmetric, with local mean equals zero and the same number of zero-crossing and extremes. The developed technique was tested on synthetic and real data, and the results were considered encouraging

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The seismic processing technique has the main objective to provide adequate picture of geological structures from subsurface of sedimentary basins. Among the key steps of this process is the enhancement of seismic reflections by filtering unwanted signals, called seismic noise, the improvement of signals of interest and the application of imaging procedures. The seismic noise may appear random or coherent. This dissertation will present a technique to attenuate coherent noise, such as ground roll and multiple reflections, based on Empirical Mode Decomposition method. This method will be applied to decompose the seismic trace into Intrinsic Mode Functions. These functions have the properties of being symmetric, with local mean equals zero and the same number of zero-crossing and extremes. The developed technique was tested on synthetic and real data, and the results were considered encouraging

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The objective of this Doctoral Thesis was monitoring, in trimestral scale, the coastal morphology of the Northeastern coast sections of Rio Grande do Norte State, in Brazil, which is an area of Potiguar Basin influenced by the oil industry activities. The studied sections compose coastal areas with intense sedimentary erosion and high environmental sensitivity to the oil spill. In order to achieve the general objective of this study, the work has been systematized in four steps. The first one refers to the evaluation of the geomorphological data acquisition methodologies used on Digital Elevation Model (DEM) of sandy beaches. The data has been obtained from Soledade beach, located on the Northeastern coast of Rio Grande Norte. The second step has been centered on the increasing of the reference geodetic infrastructure to accomplish the geodetic survey of the studied area by implanting a station in Corta Cachorro Barrier Island and by conducting monitoring geodetic surveys to understand the beach system based on the Coastline (CL) and on DEM multitemporal analysis. The third phase has been related to the usage of the methodology developed by Santos; Amaro (2011) and Santos et al. (2012) for the surveying, processing, representation, integration and analysis of Coastlines from sandy coast, which have been obtained through geodetic techniques of positioning, morphological change analysis and sediment transport. The fourth stage represents the innovation of surveys in coastal environment by using the Terrestrial Laser Scanning (TLS), based on Light Detection and Ranging (LiDAR), to evaluate a highly eroded section on Soledade beach where the oil industry structures are located. The evaluation has been achieved through high-precision DEM and accuracy during the modeling of the coast morphology changes. The result analysis of the integrated study about the spatial and temporal interrelations of the intense coastal processes in areas of building cycles and destruction of beaches has allowed identifying the causes and consequences of the intense coastal erosion in exposed beach sections and in barrier islands

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The changes that have taken place in the organizational environment in recent decades have led to new performance measurement systems being proposed, given the inadequacy of traditional models. The Balanced Scorecard (BSC) emerged as an instrument to translate financial and non-financial assets into real values for all interested parties in the organization, allowing the introduction of strategies to achieve the desired goals. Research shows that most errors committed with the use of this method are related to the implementation process. Thus, the aim of this dissertation is to analyze the process of building and implementing the BSC in an organization. This empirical exploratory study is based on the classic case study method, which enables the researcher to work with a set of evidence, including direct observation, interviews and document analysis. The results show that the use of BSC in the company investigated posed problems during the process of building and implementing the method. These problems were caused mainly by the lack of involvement on the part of upper management and the team s scant knowledge of Balanced Scorecard. One of the gains obtained from adopting the system was the introduction and/or consolidation of a culture of strategic planning and participative management. The continuous implementation phase was highlighted in the monitoring program, created by the organization in an attempt to reverse existing problems, using the BSC as a third generation strategic management system, which led to significant gains, better use of the system and stronger management practices

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This research aims to identify the process of appropriation of audio visual (in digital video) for collective symbolic production (participatory video practice that expresses popular culture) in a socio-cultural context where the minorities are. Therefore, we based this study on the students‟ experience of the film and video workshops held by Cinema para Todos (Culture Point Cine for All), in Natal, RN. Culture Point is the basis of the project Programa Nacional de Cultura, Educação e Cidadania Cultura Viva (National Program of Culture, Education and Citizenship - Living Culture) of the Brazilian Ministry of Culture. In 2010, the Cine for All developed three film and video workshops in the state of Rio Grande do Norte (Northeastern of Brazil), in the municipalities of Açu, Lajes and São Gonçalo do Amarante, within a public policy project of socio-cultural inclusion. These three workshops are the focus of this empirical investigation. To support the analysis of this research we consider that the spaces of workshops are sites of the social practices origin, assuming they show the development of the changes of actions that generate new practices. In this socio-cultural context the students as interlocutors process the communicative culture mediation, where come from the logics of action (using digital video) to become a mediatic practice (video auto ethnographic). With the overall goal set and the field of investigative action delimited we considered the methodology of case study suitable for the observation of the object, because it is a phenomenon of modernity, occurring in a context of real life and with little or no control over events. Participant observation and interviews was also applied to this case study. The analytical theoretical support comes from the notion of mediation by Jesús Martín-Barbero and the concept of habitus by Pierre Bourdieu. The research found that a new way of communicating has been developing by this social group, and this reflects the technological change experienced by them. The auto ethnographic videos, short movies, reveal an allegorical trial of the mainstream media, because while they use the mainstream format, they rework the aesthetic, but without revising the history, in fact they proposing to retell the history of themselves full of colorful details and with richness of their forgotten popular culture.

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The literature has shown a relation between periodontics and the removable partial denture (RPD), with progressive destruction observed in the support structures. The aim of this study was to clinically assess periodontal condition in users of removal partial denture (RPD), and compare right abutments teeth, indirect abutments and controls before installation and after 1 year, in addition to comparing tooth-supported and tooth mucosa-supported abutments. A total of 50 patients, 32 women and 18 men, mean age of 45 years, took part in the study. The patients were examined by a single examiner at prosthesis installation and after 3, 6, 9 and 12 months. The following were verified at each examination: Probe Depth (PD), Plaque Index (PI), Gingival Index (GI), the amount of Keratinized Mucosa (KM), Gingival Recession (GR) and Dental Mobility (DM); in addition patients received oral hygiene orientation, accompanied by prophylaxis, periodontal scaling and root planing (PSRP), when necessary. Analysis of Variance (ANOVA) with Tukey-Kramer post test was used to assess the dependent variables (PD, PI, KM, GR) of the three groups over time while Friedman s test was used for GI. To assess the outcomes of prosthesis type in the right abutment group, a confidence interval-based analysis was performed. The results showed that the control group was the least compromised in all the variables studied. With respect to development of the groups over time, it was verified that the measures for GR, PD, GI and KM increased from initial examination to 1 year of use in all the groups, but only PI showed a significant increase. There was a non-discriminatory low prevalence of dental mobility. The tooth mucosa-supported prosthesis had significantly higher values for GR, GI and PI and significantly lower ones for KM when compared to tooth-supported. Over time, both types of prostheses showed no significant differences from initial to final examination for the variables GR, PD, KM and GI, with PI significant only for tooth-supported. The results showed that the teeth most involved in RPD design had greater potential of periodontal damage, probably because of greater dental biofilm accumulation. Abutments elements adjacent to the free extremities had less favorable periodontal condition than those adjacent to interpolated spaces, but the use of RPD did not worsen the initial condition

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This study arises in the context of physics teacher training and aims, from the speech of the teacher trainer, identify possible pedagogical models and characterize thinking styles present in the course of licentiate in physics of IFRN using the epistemology of Ludwik Fleck. We classify our research as qualitative with an empirical nature, and for the analysis we chose the discursive textual analysis - DTA (MORAES, 2003). The locus of our research will be the licentiate in physics at the Federal Institute of Education, Science and Technology of Rio Grande do Norte - IFRN, Natal-Central Campus and the research subjects, a group of teacher trainers of this course. We interviewed ten teachers, being six from the group dedicated to physics and four from the group dedicated to didactics and pedagogy. From this design, we performed data acquisition consisted of: 1) semi-structured interview, 2) document analysis. On the data analysis, with the support of pedagogical trends that were observed in our study based on the perception of the similarities and differences between the ideas presented by teachers about: education and teaching; ideal teaching practice, teacher's role, learning conceptions, and according to the student and on the ideological thinking of these former teachers on the professional profile of graduates, we noted subsidies to identify evidences of the presence of three distinct thinking styles that interrelate with each other in a considerably intense way. The relevance of the study is presented in the understanding of thinking styles that participate in the dynamics of the course of teacher training in physics, and by consequence, elucidation of a problem pointed out a priori as motivating the research: the difficulty of communicative interaction on educational practices among teacher trainers. We bring Fleck's epistemology as a motivating possibility of dialogue and negotiation, setting thus an instrument of real change, towards the significance of teacher training in physics.

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Analogous to sunspots and solar photospheric faculae, which visibility is modulated by stellar rotation, stellar active regions consist of cool spots and bright faculae caused by the magnetic field of the star. Such starspots are now well established as major tracers used to estimate the stellar rotation period, but their dynamic behavior may also be used to analyze other relevant phenomena such as the presence of magnetic activity and its cycles. To calculate the stellar rotation period, identify the presence of active regions and investigate if the star exhibits or not differential rotation, we apply two methods: a wavelet analysis and a spot model. The wavelet procedure is also applied here to study pulsation in order to identify specific signatures of this particular stellar variability for different types of pulsating variable stars. The wavelet transform has been used as a powerful tool for treating several problems in astrophysics. In this work, we show that the time-frequency analysis of stellar light curves using the wavelet transform is a practical tool for identifying rotation, magnetic activity, and pulsation signatures. We present the wavelet spectral composition and multiscale variations of the time series for four classes of stars: targets dominated by magnetic activity, stars with transiting planets, those with binary transits, and pulsating stars. We applied the Morlet wavelet (6th order), which offers high time and frequency resolution. By applying the wavelet transform to the signal, we obtain the wavelet local and global power spectra. The first is interpreted as energy distribution of the signal in time-frequency space, and the second is obtained by time integration of the local map. Since the wavelet transform is a useful mathematical tool for nonstationary signals, this technique applied to Kepler and CoRoT light curves allows us to clearly identify particular signatures for different phenomena. In particular, patterns were identified for the temporal evolution of the rotation period and other periodicity due to active regions affecting these light curves. In addition, a beat-pattern vii signature in the local wavelet map of pulsating stars over the entire time span was also detected. The second method is based on starspots detection during transits of an extrasolar planet orbiting its host star. As a planet eclipses its parent star, we can detect physical phenomena on the surface of the star. If a dark spot on the disk of the star is partially or totally eclipsed, the integrated stellar luminosity will increase slightly. By analyzing the transit light curve it is possible to infer the physical properties of starspots, such as size, intensity, position and temperature. By detecting the same spot on consecutive transits, it is possible to obtain additional information such as the stellar rotation period in the planetary transit latitude, differential rotation, and magnetic activity cycles. Transit observations of CoRoT-18 and Kepler-17 were used to implement this model.

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This work appears as a reflection on the oral modality of the language in the teaching of Portuguese Language from textbooks proposed for the elementary school. It has as main aim to analyze the textbooks for the Youth and Adult Education - EJA (6th and 7th grade), the collection "It is time to learn", specifically in regard to educational activities focusing on oral proposals in their constituent units. It is a process of reflection with a view to submitting suggestions arising from the discussions held, given the fact that the writing mode has been identified by some scholars, between these Marcuschi (2005), as the most privileged in the classroom and in most manuals that guide the teaching of Portuguese Language. In this work, we start from a broader vision from the principles of dialogic pedagogy by Paulo Freire perspectives towards pedagogical practices that favor the development of linguistic and discursive student skills. In this sense, we emphasize the formation of a critical subject, who can argue and defend points of view, using oral or written language, in various social situations. In this view, this paper set up aims to identify, describe and interpret the activities proposed to the oral modality of Portuguese Language, from interactional theoretical bases, based on authors as Marcuschi (2005, 2010), Fávero, Andrade and Aquino (1999) Schneuwly and Dolz (2004), Antunes (2009), among others. In addition, the objective was to suggest other educational activities, as a way of expanding the existing ones, in order that addressed more efficiently, to aspects of orality been proposed and aspects of formal oral genres. Methodologically, it is a qualitative research, in which, from the teaching materials used in the classroom, there was a reflection on the orality and the oral teaching of the Portuguese language and has been proposed an expansion of activities one oral mode. In this reflection, analysis of the results revealed that the books investigated, used in Portuguese classes in EJA, include in their proposals orality as an object and teaching axis. However, we appoint the need to expand the teaching proposals with the existing activities in order to give greater emphasis to important aspects of orality already prioritized, and also to address to the formal public genres. In seeking to make suggestions and educational proposals that integrate with existing, we postulated the most effective development for oral skills for the EJA student, in Freire's perspective, as also we thought in a way to provide subsidies which could guide teachers of the Portuguese Language area at the fundamental level of education.

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The objective of this Doctoral Thesis was monitoring, in trimestral scale, the coastal morphology of the Northeastern coast sections of Rio Grande do Norte State, in Brazil, which is an area of Potiguar Basin influenced by the oil industry activities. The studied sections compose coastal areas with intense sedimentary erosion and high environmental sensitivity to the oil spill. In order to achieve the general objective of this study, the work has been systematized in four steps. The first one refers to the evaluation of the geomorphological data acquisition methodologies used on Digital Elevation Model (DEM) of sandy beaches. The data has been obtained from Soledade beach, located on the Northeastern coast of Rio Grande Norte. The second step has been centered on the increasing of the reference geodetic infrastructure to accomplish the geodetic survey of the studied area by implanting a station in Corta Cachorro Barrier Island and by conducting monitoring geodetic surveys to understand the beach system based on the Coastline (CL) and on DEM multitemporal analysis. The third phase has been related to the usage of the methodology developed by Santos; Amaro (2011) and Santos et al. (2012) for the surveying, processing, representation, integration and analysis of Coastlines from sandy coast, which have been obtained through geodetic techniques of positioning, morphological change analysis and sediment transport. The fourth stage represents the innovation of surveys in coastal environment by using the Terrestrial Laser Scanning (TLS), based on Light Detection and Ranging (LiDAR), to evaluate a highly eroded section on Soledade beach where the oil industry structures are located. The evaluation has been achieved through high-precision DEM and accuracy during the modeling of the coast morphology changes. The result analysis of the integrated study about the spatial and temporal interrelations of the intense coastal processes in areas of building cycles and destruction of beaches has allowed identifying the causes and consequences of the intense coastal erosion in exposed beach sections and in barrier islands