Teses e Dissertações

URI Permanente desta comunidade

http://repositorio.ufes.br/handle/10/17332

Nesta comunidade encontram-se todas as teses e dissertações depositadas no repositório da Universidade Federal do Espirito Santo

Navegar

Agora exibindo 1 - 20 de 13026

Analise comparativa de algumas estruturas de filtros digitais de segunda ordem imunes a ciclos limite
(Universidade Federal do Espírito Santo, 1994-08-19) Simmer, Ana Cristina Staut; Orientador1; Sarcinelli Filho, Mário
This work is a comparative study of the relative output roundoff noise variance performance for some second-order state-space structures, as a function of the filter bandwidth. The addressed second-order structures are used as building blocks for realizing lowpass, highpass, bandpass and bandreject digital filters. In this sense, this study complements a recent one, which just investigated the lowpass filter case. In both studies only narrow-band digital filters are discussed, regarding the well known good performance of the state-space structures in those cases. In order to compare the output roundoff noise performance for all spectra, new firstorder spectral transformations, derived from the well known transformations due to Constantinides, are developed, for varying the filter bandwidth of a parallel-form prototype filter. All this effort is justified by the importance of knowing the performance of the structures which are suitable for a desired application, what represents a significative contribution to the problem of designing digital filters.
Uma interface gráfica de usuário para projeto e implementação de filtros digitais com processador dedicado
(Universidade Federal do Espírito Santo, 1996-06-19) Machado, Arnaldo Cordeiro; Schneebeli, Hans Jorg Andreas; Sarcinelli Filho, Mário; Coradine, Luis Claudius; Pequeno, Mauro Cavalcante
This work describes a software platform developed in order to support the design and DSP-based implementation of digital filters. It is a WINDOWS program designed to run on a personal computer containing a DSP board. A card based on the 16-bit fixed point Texas Instruments TMS320C25 chip is used, which is attached to the ISA PC bus. The developed software is specially designed to accomplish three main features: the filter design task, restricted to the PC microprocessor, the real-time synchronous filter algorithm, running exclusively on the DSP, and the necessary information exchanging between both processors, and between the PC computer and the user, in order either to load filter parameters or to check for the filter input/output signals. In addition, the user may edit/view text files containing the filter transfer function or network coefficients, or edit/compile/debug files that contain assembly code for the DSP.
A utilização da violência na atividade policial: da insanidade coletiva à loucura solitária
(Universidade Federal do Espírito Santo, 1998-07-28) Cavassani, Sonia Maria Correa; Souza, Lídio de; Bretas, Marcos Luiz; Menandro, Paulo Rogério Meira
The literature about the police activities have emphasized a complex relationship between society and the police, detaching a historically working discriminatory and regulated by violent method, indicating direct involvement of the police activities to the interests of the domination class. In this context is unusual if it analyzes the conception of the police themselves. This work had the purpose to identify, through collected information together with the civil police, conceptions about the utilization of violent methods, the police functions, discriminatory working, the reasons for the ingress and the remaining in the institution, as well conceptions about the causes of the police getting sick and the relationship with other cops that have been already sick. The sample, was organized by 60 agents and investigators from the police department both male and female, classified into two groups: Gl: 30 people with medicai license, originated from mind’s disturbing, and Gll: 30 people without medicai license. The data were collected by organized questionary from highlighting the topics already mentioned. It was found significant difference statistically between the two groups of people considering most of the subject that had been approached. The results show a scission accentuated among cops followers and against of utilization of violence and consequently organization of reciprocai out-groups building a complex game of relations inter-groups ruled by the exclusion. The process for becoming sick, lived by some cops reflect with high rank of fidelity of the stress originated not only form the kind of work done, but mainly the opposition of conceptions about what must be the police institution and their method of work.
Sobre o projeto de filtros digitais de segunda ordem imunes a ciclos limite
(Universidade Federal do Espírito Santo, 1998-12-30) Camponêz, Marcelo Oliveira; Sarcinelli Filho, Mário; Calmon, Luiz de Calazans; Mota, Francisco das Chagas
A set of three constant-input limit cycle-free state-space second-order digital filtersections were proposed in a paper of 1986, to be used as building blocks for cascade orparallel higher order filter design. They were called structure type I, structure type II (which isentirely identical to the first one) and structure type III, by the authors who proposed them.Those structures are different from other constant-input limit cycle-free second-orderbuilding blocks in the sense that they are computationally less complex. As showed in thepaper that introduced it, the structure type I is also a low roundoff noise one, when comparedto the minimum noise structure designed under L∞ scaling. Unfortunately, because thestructure type III is slightly more complex than the structure type I (its demands three two-input adders more to be computed), its synthesis procedure and noise performance were notaddressed in the initial paper. However, it was demonstrated later, that the structure type IIIpresents relative output roundoff noise variances lower than the structure type I for the case ofL2 scaled lowpass filters.Then, in this work, the structure type III is revised, and new strategies for designing itare proposed. Under proper design, it is showed that the relative output roundoff noisevariance is minimal. Both L2 and L∞ scaling are here discussed. Examples are shown tosupport the results presented.Finally, in order to stress the good noise performance of the structure type III designedaccording to the strategies here discussed, it is compared to the noise performance of someother filter structures known in the literature. The conclusion is that the new structure type IIIhere proposed is a good candidate for being the building block to implement high ordernarrowband filters.
Sistema de visão para robôs móveis: uma aplicação ao reconhecimento de referências geométricas
(Universidade Federal do Espírito Santo, 1999-02-26) Freitas, Roger Alex de Castro; Sarcinelli Filho, Mário; Bastos Filho, Teodiano Freire; Almeida, Ailson Rosetti de; Rillo, Márcio
The availability of sensorial data is an important issue for the navigation systemof autonomous mobile robots. The robot needs information about its surroundingenvironment in order to make a decision on what to do when it faces an obstacle. Insome cases, it not only does need to detect the presence of the obstacle but also torecognize it. This way, it is necessary that the onboard sensing system be much morespecialized. For an agent-based controlled autonomous mobile robot, a sensing systemthat combines ultrasonic sensors and artificial vision is here addressed. It makesavailable information about the type of obstacle detected in the trajectory of the robot, aswell as the distance from the detected object to the robot. This external sensing systemis also able to avoid the generation of redundant and unnecessary information, besidesnot demanding too much computational effort to process the acquired images onboardthe robot
Formulação do método dos elementos de contorno com dupla reciprocidade usando elementos de ordem superior aplicada a problemas de campo escalar generalizado
(Universidade Federal do Espírito Santo, 1999-03-12) Bulcão, André; Loeffler Neto, Carlos Friedrich; Oliveira, Paulo César
The formulation and application of the Boundary Element Method to problems embodied by the so called Scalar Field Theory are presented. In the formulation, it is used the Dual Reciprocity Technique to treat domain integrals for which traditional procedures can not transform the integral equation into an algebraic equation linear system, only involving variables along the boundary. The Scalar Field Theory is widely applied to several Engineering areas, such as: Thermosciences, Fluid mechanics, Solid Mechanics, Electromagnetism, Corrosion, among others. In the presented applications, the problems are physically interpreted mainly though Heat Transfer and Solid Mechanics. Besides, several analysis of problems ruled by Laplaceís, Poissonís and Diffusion Equations are presented. Basically, aiming to estimate the Boundary Element Method performance, certain parameters - which influence its results, such as the refinement level used in the discretizations - are varied and different boundary element types are considered. For such, the obtained numerical solutions are compared with the analytical ones, or even with those originated by the application of other numerical methods. In some cases, it is drawn a parallel between the performance of the Boundary Element method with the Finite Element Method, or either with the Finite Volume Method.
Uma contribuição ao estudo do processo de projeto de empreendimentos em construção metálica: uma visão segundo a nova filosofia de produção.
(Universidade Federal do Espírito Santo, 2000-06-19) Moraes, Flavia Rosindo de; Gama, João Luiz Calmon Nogueira da; Heineck, Luiz Fernando Mählmann; Oliveira, Marcel Olivier Ferreira de
Steel construction first appeared in Brazil 50 years ago, but only in the last fifteen years has it been rediscovered by contractors and professionals that have become more interested in this kind of building technology. There are many factors which regulate steel construction development, but incentives are growing in order to increase the steel consumption in civil construction, because this consumption is lower than others countries. Talking about the industrialization of construction, the integrated design is very important and the New Production Philosophy (lean production) is a good reference theory for the design process improvement. Thus, the design process improvement is fundamental to enhance production process efficiency. The characteristics of the product are defined by the design and these characteristics influence production costs. This study starts with an exploratory research, looking through the definition of the case study focus. Aspects like market, costs, technology, planning, productivity, standards, design, waste, quality, labour and problematic topics about steel construction were examined and deficiencies in the design stage were noted. After this, the study investigates two design processes of steel construction projects, analyzing then in accordance with the New Production Philosophy. Finally, this study suggests some actions and policies for improving the design process in steel projects.
"Menina não entra": um estudo da segregação sexual na interação ludica de crianças de 8 e 9 anos
(Universidade Federal do Espírito Santo, 2000-11-24) Souza, Fabrício de; Rodrigues, Maria Margarida Pereira; 1º membro da banca
Influência do cobre na ductilidade a quente dos aços
(Universidade Federal do Espírito Santo, 2001-02-16) Pauli, Evandro Armini de; Cominelli, Oswaldo Guilherme; Macedo, Marcelo Camargo Severo de; Alé, Ricardo Miranda; Furtado, Henrique
The influence of different additions of Cu and cooling rate on the hot ductility of steels have been examined, in the temperature range 750 a 950°C, at low strain rate of 2x10-3 s -1 . The effect of increasing Cu level has been found negligible to samples tested at high cooling rate. Samples tested to low cooling rate were more sensible to the Cu level variation, those having high Cu showing impairment in the hot ductility. Cu rich phases have been found in all testing conditions apart from a single one of low Cu and fast cooling rate where no Cu rich phases have been found. Those Cu rich phases apparently have little or no effect on the hot ductility of steels investigated.
Estudantes de medicina e suas atitudes em relação à AIDS
(Universidade Federal do Espírito Santo, 2001-05-28) Frauches, Diana de Oliveira; Rodrigues, Maria Margarida Pereira; Enumo, Sônia Regina Fiorim; Leal, Eroltildes Maria
The attitudes of professional health workers towards AIDS may cause deviations in technical behavior and evaluating students' attitudes while they are still in graduate schools may allow eventual actions before practice starts, thus avoiding the establishment of negative attitudes. Based on the fact that attitudes knowledge, affection and evaluation have their origins in social life and are largely shared, and considering that the attitudes towards AIDS may be related to professional training, in addition to existing controversies about the influence of gender, a probabilistic sample of 176 medical students, arranged according to sex and insertion in the course, was selected from the first and last college years, belonging to both two medical schools located in Espirito Santo, Brazil. The Scale of Attitudes towards AIDS (AAS), developed by Shrum, Turner and Bruce, was adapted and applied to the studied population distributed in groups according to school and insertion in the course. The results were analyzed using statistics non-parametric tests. The freshmen attitudes from both medical schools were similar. In one of the schools, the tolerance increased among the last year students in comparison with the first year students, while it decreased in the other school, with growth of the variegation of the scores. The "religion" and "knowing HIV/AIDS people" variables, that were considered too, didn't produce significant differences. Also there were not significant differences between gender in the first year group. It is discussed the adjustment of AAS to be used in our environment. The proposal of further studies to know the pedagogical projects and culture of the schools were this research took place is considered, as well as the role of gender in the students' attitudes towards AIDS.
Adolescentes com diabetes Mellitus tipo 1 :seu cotidiano e enfrentamento da doença
(Universidade Federal do Espírito Santo, 2001-08-23) Santos, Jocimara Ribeiro dos; Enumo, Sônia Regina Fiorim; Menandro, Paulo Rogério Meira; Günther, Isolda de Araújo
The adolescence period has been studied under different approaches, and there are divergences about its universality. It is known, however that the physical transformations of puberty also cause psychosocial changes. This redefinition of roles, thoughts and attitudes can be quite influenced by the existence of a chronic disease as Diabetes Mellitus Type 1, which has the incidence of 1 or 2 in each hundred adolescents. They may have their daily routine altered. With the aim to describe and analyze how Diabetes Mellitus Type 1 affect adolescents’ coping and organize their daily routines, a comparison was made between adolescents with and without the disease. This research was undertaken with 15 adolescents (6 male and 9 female, with their age ranging from 12 to 20 years) enrolled in the Vitória’s public health Diabetes Mellitus Bearers Attendance Programs. The subjects were submitted to the collective and individual application of Daily Activities Map (DAM), (Menandro, Menandro & Oliveira, 1999) and to a closed/open individual interview, about coping. The DAM was applied collectively to 224 young adolescents without disease (122 girls and 102 boys, their age ranging from 12 to 20 years), students from Medium and Fundamental levels, from public schools in greater Vitória/ ES, for a comparative comparison. The data obtained from DAM were analysed through quantitatively and qualitatively analyzed, intending a differentiated evaluation of the author’s proposal; the interviews were content analysis. The data revealed that activities more accomplished by the adolescents were: activities directed to themselves, activities inside their home, pleasant ones, social ones, and that it involved action and control to alcohol consume. The activities more accomplished inside the house were: attending television programs and listening to some music. Despite the joet that Diabetes Mellitus Type 1 affected adolescents, pointing some difficulties in relation to the disease, they didn’t have their routine modified because of the disease. The results indicated that the adolescents with diabetes do not differentiate, in a significant way, from those without the disease.
Caracterização gravimétrica e comercial dos resíduos sólidos urbanos recolhidos em Postos de Entrega Voluntaria do sistema de Coleta Seletiva da Prefeitura Municipal de Vitória-ES
(Universidade Federal do Espírito Santo, 2001-12-13) Laignier, Irene Thomé Rabello; Braga, Florindo dos Santos; 1º membro da banca
This work aimed to characterize the dry and solid urban waste comercialized by Usina de Lixo de Vitória – ES composed of Voluntary Delivery Offices (Postos de Entrega Voluntária - PEV), implemented by the city of Vitória, capital of Espírito Santo. Fieldwork was developed along with the practical techniques of collect, transportation and a process of selection for later recovery used by the existent system, under tecno-scientific criteria. From the analysis of the results it is concluded that the waste from the PEVs of selective collect had in its composition 38% paper, 19% glass, 13%, plastic and 8% ferrousand non-ferrous metals and 22% discards and the utilization index of the recycle materials taken in the PEVs was about 77%. The acts of vandalism against PEVs are not very significative. Laterly was stimated the number of users that utilize the system of selective collect to dispose the recycle materials that they own produce. Finally was established a relationship between the locations of these collectors and their own filling in level. Because it is the first avaliation of this kind of collect, in the state of ES, hopefully that the results taken, come to contribute for a management and planning in case of expansion of the selective collect in Vitória or even in the implementation of this kind of collect in the other cities.
As expectativas do ter e o fracasso do ser: representações sociais de adolescência e suicídio entre adolescentes
(Universidade Federal do Espírito Santo, 2002-08-13) Silva, Priscilla de Oliveira Martins; Almeida, Ângela Maria de Oliveira; Trindade, Zeide Araujo; Menandro, Paulo Rogério Meira; Queiroz, Sávio Silveira de
The present work aims to discuss a phenomenon which has been occured often among the adolescent population: the suicide. In the scientific literature there are a few studies that understands that phenomenon in a psychossociological approach, the majority of the studies are focused on the sociological, psychological and psychiatrically approaches. Based on the Theory of Social Representation we analyze the meaning of adolescence and suicide among adolescents and verify the possible relations between these two themes. 360 adolescents of 14 to 23 years old participated in this research; 180 (90 female and 90 male) that live in a urban area and that study in a private school which is located in a neighborhood considered of a high-middle class and high class, and 180 (90 female and 90 male) that live in a rural area and that study in a agrotecnical public school. The results pointed out that the way each group represent the suicide depends on the way they live their adolescence. To the urban area group the social representation of adolescence is configured in two main themes: -party on? and support. The first one means the peer socialization and the second one the parental support. The main concern to this group is being alone. Therefore, the risk factors related to suicide are family problems such as: parental divorce, maltreatment, parental neglect, among others; and problems in relating with others, that can be related to self steam, psychiatric syndromes, among others. The rural area group represents adolescence as a quick transition to adulthood, thus, they are concerned with professional market reality, and not only with loneliness. Therefore the risk factors to these adolescents are the mentioned to the group that live in a urban area and social problems such as: unemployment, low wages, financial difficulties, among others. From the results we conclude that, to have a good adolescent health treatment is indispensable knowing better the adolescents‘ fears, life projects, beliefs, social context in order to provide a effective group of action on that way.
As expectativas do ter e o fracasso do ser: representações sociais de adolescência e suicídio entre adolescentes
(Universidade Federal do Espírito Santo, 2002-08-13) Martins, Priscilla de Oliveira; Almeida, Ângela Maria de Oliveira; Trindade, Zeidi Araújo; Menandro, Paulo Rogério Meira; Queiroz, Sávio Silveira de
The present work aims to discuss a phenomenon which has been occured often among the adolescent population: the suicide. In the scientific literature there are a few studies that understands that phenomenon in a psychossociological approach, the majority of the studies are focused on the sociological, psychological and psychiatrically approaches. Based on the Theory of Social Representation we analyze the meaning of adolescence and suicide among adolescents and verify the possible relations between these two themes. 360 adolescents of 14 to 23 years old participated in this research; 180 (90 female and 90 male) that live in a urban area and that study in a private school which is located in a neighborhood considered of a high-middle class and high class, and 180 (90 female and 90 male) that live in a rural area and that study in a agrotecnical public school. The results pointed out that the way each group represent the suicide depends on the way they live their adolescence. To the urban area group the social representation of adolescence is configured in two main themes: -party on? and support. The first one means the peer socialization and the second one the parental support. The main concern to this group is being alone. Therefore, the risk factors related to suicide are family problems such as: parental divorce, maltreatment, parental neglect, among others; and problems in relating with others, that can be related to self steam, psychiatric syndromes, among others. The rural area group represents adolescence as a quick transition to adulthood, thus, they are concerned with professional market reality, and not only with loneliness. Therefore the risk factors to these adolescents are the mentioned to the group that live in a urban area and social problems such as: unemployment, low wages, financial difficulties, among others. From the results we conclude that, to have a good adolescent health treatment is indispensable knowing better the adolescents fears, life projects, beliefs, social context in order to provide a effective group of action on that way
Controle de robôs móveis por fusão de sinais de controle usando filtro de informação descentralizado
(Universidade Federal do Espírito Santo, 2002-08-14) Freire, Eduardo Oliveira; Bastos Filho,Teodiano Freire; Sarcinelli Filho, Mário; Carelli, Ricardo; Schneebeli, Hansjörg Andreas; Nasisi, Oscar; Salles, José Leandro Felix; Bergerman, Marcel
This thesis proposes an alternative approach to deal with the problem of mobile robot navigation, which is called fusion of control signals. The proposed technique has presented good results when a robot has to execute relatively complex tasks, like it is shown in the experiments here presented. The technique is developed with basis on the decentralised information filter, whose equations are here derived from the equations of the decentralised Kalman filter and the information filter. Motion controllers available in the literature and others introduced here for the first time are used to produce the control signals that are fused using a decentralised information filter in order to produce the overall output signal to be sent to the actuators. A stability analysis of the proposed architecture is also addressed.
Análise dos estágios iniciais da corrosão de aço-carbono e aço patinável expostos em ambiente marinho-industrial e rural
(Universidade Federal do Espírito Santo, 2002-09-02) Oliveira, Luciano Sacramento de; Queiroz, Rogério Silveira de; Macêdo, Marcelo Camargo Severo de; Larica, Carlos; Bastos, Ivan Napoleão
ASTM A36 and ASTM A242 steel samples were exposed for 4 months in marineindustrial and rural sites. The meteorological conditions and the SO2, SO4 -2, Cl- and TSP concentrations were evaluated during all the research period. The corrosion products were characterized by x-ray difractometry and Mössbauer spectroscopy. The samples exposed in rural environment showed g-FeOOH and g-Fe2O3, while samples exposed in marine-industrial environment showed a-FeOOH and g-FeOOH. Corrosion rates and thickness losses were determined through mass loss essay. ASTM A36 mass loss was larger than ASTM A242 mass loss. Simple linear regressions were performed for mass loss in function of time and multiple linear regressions were performed in order to produce equations for corrosion rates in function of environmental parameters for ASTM A36 and ASTM A242 steels. It was verified that Cl- and SO4 -2 ions were the more influent factors in corrosion of samples exposed in marine- industrial environment. There must be a competitive adsortion process between Cl- and SO4 -2 ions for marineindustrial environment. For samples exposed in rural environment, it was verified that pollutants probably don t influence linearly their corrosion rates. Therefore, meteorological factors as humidity must be more important to corrosion of steel exposed in this environment.
Análise do comportamento dos pilares mistos considerando a utilização de conectores de cisalhamento
(Universidade Federal do Espírito Santo, 2002-09-08) Bianchi, Flavia Regina; Sá, Pedro Augusto Cesar Oliveira de; Coelho, Luiz Herkenhoff; Menandro, Fernando César Meira; Rodrigues, Francisco Carlos
The steel-concrete composite structures are systems that involve the interaction of structural steel components with concrete elements to resist external forces. This interaction between steel and concrete should be guaranteed to ensure that loads are supported. As such, adhesion tensions between the concrete and the steel should not be exceeded. In cases where they are, the use of shearing connectors becomes necessary. The influence of the use of shearing connectors in composite columns is greatly undervalued in the majority of scientific papers, with its use recommended only in situations of high vibration. In this paper, the behavior of composite columns is analyzed with the use of shearing connectors taken into consideration through numerical analysis using Ansys programming and based on the finite element method. To achieve this, an ideal model that reflects the situation was adopted permitting as study of the element, the load, and the contour conditions adequate for usage. Composite columns with and without shearing connectors were modeled. A load was applied to each model with varying eccentricity to create an interaction curve defining the moment of flexion in function of normal force. From the interactive curves that were constructed, the importance of the use of shearing connectors was analyzed. This analysis compares results to data supplied by EUROCODE 4(1994) and the influence of different values for maximum adhesion tension of the last load of the composite column.
Geração energética e processos tecnológicos sustentáveis : impasses e alternativas para o Brasil
(Universidade Federal do Espírito Santo, 2002-10-28) Bragato, Cláudia Guio; Dalcomuni, Sonia Maria; Arthmar, Rogério; Almeida, Luciana Togeiro de
The following research approaches the interaction between the technological paradigm subjacent to the Brazilian energetic power nucleus and environment, centralising on the electricity generation centre, in a sustainable growth perspective. One searches to think over whether the Brazilian power supply crisis noticed in April 2001 and consequent actions and as well as quests for solutions to the resolution of the same, tends to solve or block the sector development and the Brazilian economy in a perspective of economic growth associated to social equity and environmental protection, according to what s been prioritised by sustainable development concept. Hence, the technological options for currently used powergenerating techniques and those in discussion are analysed regarding its positive and negative aspects in terms of generating environmental external influences. Technological innovation is focused as an alternative capable of changing the hydrocarbon paradigm predominant in the world power supply generation. One does a historical rescue of the sector development, also approaching the main reforms on the Brazilian electric institutional sector up to the current configuration aimed at knowing the new sector agents involved in the regulatory process, integration, and support. Through the analysis of internal or external conditioners, one can figure their capability of contributing or delaying the adoption of a sustainable trajectory for the national electric sector. The achieved conclusion is, despite worrying on maintaining its energetic nucleus clean, Brazil, at a first moment, provided the acquiring of a Priority Thermoelectric Program , that even though having a complementary character to the actual generating park, will be able to contribute to an energetic dependence on a pollutant fossil combustible, amongst other existent possibilities, without ensuring the inexistence of the future supply crisis. The transformation in concepts, as well as society values will indeed contribute for the restructuring of global energetic economy, boosting the renewable sources portion within the world energetic nucleus and will allow humanity economic progress growth, facing a wider continuing power demand in the future.
Navegação reativa de robôs móveis com base no fluxo óptico
(Universidade Federal do Espírito Santo, 2002-12-11) Caldeira, Eliete Maria de Oliveira; Schneebeli, Hans Jorg Andreas; Sarcinelli Filho, Mário; Campos, Mário Fernando Montenegro; Rillo, Márcio; Bastos Filho, Teodiano Freire; Salles, Evandro Ottoni Teatini
This Ph. D. Thesis proposes to perform the navigation of mobile robots using a sensing system completely based on the optical flow which is calculated from a sequence of two images acquired by a camera fixed onboard the robot. To check the feasibility of using the proposed sensing system, a control system is designed to give the robot the capability of reacting to environmental changes, while executing the wander behavior with obstacle avoidance. The control system uses only data coming from the visual sensing system based on the optical flow. No modification is required to the robot’s environment, such as adding suitable textures or adjusting illumination. The optical flow is calculated considering that images are acquired when the robot is moving ahead with a null angular velocity. Then, a segmentation algorithm based on the optical flow field is proposed and implemented to detect distinct objects present in the scene. The distance from the robot to each object is then estimated based on the time to impact calculated from the optical flow field. The control system uses the time to impact corresponding to each object to determine a new direction to be followed by the robot. It then sends to the robot actuators the suitable commands to change the robot’s orientation. Both the sensing and control systems are implemented onboard a Pioneer 2-DX mobile robot and are used in a set of experiments, and the results show that the navigation system implemented presents very good performance.
Um novo perfil interpolante aplicado ao método de volumes finitos em situações une e bidimensionais
(Universidade Federal do Espírito Santo, 2002-12-17) Santório, Carlos Alexandre; Oliveira, Paulo César; Loeffler Neto, Carlos Friedrich; Mansur, Webe
In this report, a new scheme of discretization for the method of finite bulks, called FLEX which was proposed for a simulation of problems ruled by differential equations as type of elliptic and hyperbolic. Its performance was appraised through tests from the literature of numeric methods and through tests developed for all the report. The new scheme showed features of convergence and compatible and comparable stabilities to the traditional schemes of Central Difference, Power Law and Flux-Spline . Its accuracy appeared to depend on the type de physical problem. Physical problems ruled by differential partial elliptic equations implied convectiondiffusion which owns a distribution of the variable flux like one purpose by the FLEX scheme which showed a solution with the level of the error minor, in comparison with the remaining schemes. In the traditional problems case of this class, where there isn t the presence with this specific featuring the results proved to be intermediaries. To hyperbolic problems even with a poor discretization within limits of finite difference to the transient term the new scheme appeared interesting features for a simulation of this kind of phenomena in the same sense to non-refined mails to converge to the solution of reference in the rate greater than the others two schemes which were mentioned here and used in the comparison.

Navegar

Navegando Teses e Dissertações por Data de Publicação

Resultados por página

Opções de Ordenação