Mestrado em Modelagem e Otimização - PPGMO

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https://repositorio.ufcat.edu.br/handle/tede/40

O Mestrado em Modelagem e Otimização tem um papel essencial no desenvolvimento de novas tecnologias. Atualmente, se faz muito intensamente o uso de modelos matemáticos, simulações avançadas e sofisticados desenvolvimentos computacionais na pesquisa científica em geral.

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Técnicas de aprendizado profundo aplicadas ao monitoramento de integridade estrutural por impedância eletromecânica
(Universidade Federal de Goiás, 2021-07-12) Rezende, Stanley Washington Ferreira de; Moura Júnior, José dos Reis Vieira de; https://orcid.org/0000-0002-8701-8355; http://lattes.cnpq.br/2479225716217997; Moura Júnior, José dos Reis Vieira de; Rabelo, Marcos Napoleão; Lima, William Júnio de
In this work, a study of structural health monitoring (SHM) techniques is carried out, with a primary focus on the application of the eletromechanical impedance-based SHM method to characterize structural failures in mechanical systems. This methodology generally combines modern sensors with intelligent algorithms to identify the presence of damage, observing changes in the monitored signals and correlating them with physical phenomena. However, when these variations are sufficiently complex, it becomes necessary to apply more sophisticated techniques, capable of abstracting information pertinent to the condition of structural health. In this sense, innovative machine learning tools (especially Artificial Neural Networks - RNA) have been gaining prominence, being extensively investigated to avoid errors in structural prognosis and focusing mainly on vibration analysis. Therefore, the present work aims to contribute to the SHM area, providing an improvement of the electromechanical impedance technique in terms of structural health analysis, associating it with two neural architectures (CNN and LSTM) to facilitate the decision-making process. Thus, this contribution presents a bibliographical review of some of the main concepts associated with this theme, such as intelligent materials, evaluation methods, the electromechanical impedance-based method itself, the concepts associated with machine learning techniques and the artificial neural networks used. Then, four experimental tests were investigated, employing a combination of the impedance-based method with the respective CNN and LSTM architectures for the identification and/or prediction of structural failures. Thus, it was possible to validate the proposed methodologies, verifying the sensitivity of the networks to some environmental influences (such as temperature and humidity conditions) and operational (operating speed and unbalanced) influences of the mechanical systems under study. As a result, both proposed methodologies are efficient in terms of the structural health monitoring, allowing an optimization of the structural diagnosis.
Modelagem com aprendizado de máquina aplicada aos sistemas de monitoramento de integridade estrutural
(Universidade Federal de Goiás, 2021-03-25) Barella, Bruno Pereira; Cunha, Márcio José da; https://orcid.org/0000-0002-4173-8031; http://lattes.cnpq.br/5012626154282569; Moura Júnior, José dos Reis Vieira de; https://orcid.org/0000-0002-8701-8355; http://lattes.cnpq.br/2479225716217997; Moura Júnior, José dos Reis Vieira de; Cunha, Márcio José da; Costa, Vaston Gonçalves da; Gallo, Carlos Alberto
Structural Health Monitoring (SHM) using the electromechanical impedance method focuses on the development of systems responsible for monitoring the integrity of structures, such as, aerospace fuselage and metallic structures. Therefore, the use of computational tools and resources are essential. The identification, location, quantification of damage or even the prediction of the useful life of mechanical systems plays a fundamental role in ensuring the financial and public safety. That way, the use of machine learning tools is possible to perform such functions due to their high ability to identify patterns without needing to compensate for natural effects such as loading and temperature, which often act on mechanical structures. Thus, three possible approaches were applied for the development of models to be used in structural health monitoring systems, which are: anomalies detection, multi classification of damage and mass variation regression. To develop the approaches, an experiment was carried out simulating the structural damage produced by the surface machining process in a aluminum beam exposed to thermal variations between 10 ◦ C and 40 ◦ C. Systems that use machine learning have models developed with unique specifications intrinsic to the problem and, for their development, it is necessary to use tools and methods capable of performing their functions with high reliability and precision. In this sense, the main concepts of structural integrity monitoring techniques and the characteristics of intelligent materials used as sensors were presented. Subsequently, the electromechanical impedance method was approached with the essential concepts for its understanding, as well as the main systems available for collecting impedance signatures and the commonly used statistical models. Then, the common concepts and resources in the artificial intelligence field were presented, as well as tools for the analysis, interpretation and evaluation of models. Finally, a system was deployed containing the anomalie detection approach by means of a monitoring application, using the resources of containerization and cloud computing.
Atividade síncrona em redes complexas: uma abordagem matemática para estudos sobre epilepsia
(Universidade Federal de Goiás, 2021-02-22) Oliveira, Jonas Ferreira de; Abud, Celso Vieira; http://lattes.cnpq.br/5634231159637601; Abud, Celso Vieira; Macau, Elbert Einstein Nehrer; Lobato, Fran Sérgio
Synchronization in complex networks is a phenomenon present in several complex systems, ranging from neurological to electrical and mechanical to social. The most successful archetype in describing the emergence of this collective behavior in complex systems is provided by Kuramoto model. Neurological disorders such as epilepsy can be abstracted mathematically as synchronous activities in complex networks. Epilepsy is a neural disorder related to the intense synchronous neural activities due to the increase of blood flow in the cerebral cortex, causing seizures followed by fainting. Seizures can be prevented by antiepileptic drugs that fend off the emergence of synchrony in neural networks. However, about a third of medicated patients experience seizures again. Thus, the importance of studies on the recognition of synchronous patterns associated with the disorder is justified. This work does not claim to be an ultimate in the modeling of such a complex neural disorder. Therefore, the objective is to investigate which are the most influential areas of the cerebral cortex and how they influence the dynamics of synchronization associated with epilepsy. To this end, a feline's cerebral cortex was modeled as a complex network and, in order to study synchronization, Kuramoto model was used to govern of the dynamics between the areas of the cortex. The Hypertext Induced Topic Search (HITS) algorithm was used to classify pages web, in order to identify the most influential nodes in the feline cerebral cortex network. Metrics concerning the characteristics of the feline neural network and its most influential nodes, were obtained. Regarding the dynamics and measures of global, mesoscopic and microscopic synchrony, results were obtained for a scenario using the original network and two other scenarios, in which it was considered a disturbance, in order to simulate the action of an antiepileptic drug, the disturbance reduced the intensity of connections of a group containing random nodes and the group with nodes chosen by the HITS algorithm by 50%. Finally, it was found that the applied disturbance lagged the global, microscopic and mesoscopic levels of the network.
Determinação de parâmetros ótimos da equação intensidade, duração e frequência de chuvas utilizando otimização heurística
(Universidade Federal de Goiás, 2020-03-24) Santos Neto, Erivan de Paula; Sarmento, Antover Panazzolo; http://lattes.cnpq.br/4025685702530313; Sarmento, Antover Panazzolo; Rabelo, Marcos Napoleão; Rodrigues, Rafael de Ávila
Considering that the intensity, duration and frequency curves (IDF curves) are scarce and in some cases outdated for the State of Goiás, the present work aims to elaborate an algorithm capable of treating the rainfall data, coming from INMET rain gauges, and, later, through the use of heuristic algorithms, to create a program capable of determining the parameters $K$, $a$, $b$ and $c$ through the rainfall disaggregation method. The probabilistic distribution used was the Gumbel distribution, which was evaluated through the Kolmogorov-Smirnov adherence test. Then, the algorithms: genetic, ant colony, particle swarm, flower pollination and differential evolution were used to determine the parameters. Subsequently, an adjustment test was performed using the adjusted determination coefficient, Wilmott's concordance index, and the confidence coefficient to measure the performance of the proposed models. The results obtained showed that the algorithms are able to solve the problem effectively, with emphasis on the flower pollination algorithm and the differential evolution algorithm, which presented a low standard deviation and high processing speed. Regarding the adjusted determination coefficient, Willmott's concordance index and the confidence coefficient, none of them presented values lower than 0.9945, 0.9950 and 0.9923, respectively. Thus, the model and the parameters obtained effectively describe the rain data for the analyzed cities, receiving an optimal performance rating. Finally, it is concluded that the tool elaborated in this work fulfills the proposed objective, serving not only as a practical calculation tool, but also as study material.
Propriedades de escala em um modelo com comportamento coletivo
(Universidade Federal de Goiás, 2020-04-06) Silva, Jaqueline Garcia; Abud, Celso Vieira; http://lattes.cnpq.br/5634231159637601; Abud, Celso Vieira; Lobato, Fran Sérgio; Assis, Paulo Eduardo Gonçalves de
Developed for modeling the synchronization phenomenon, the Kuramoto model consists of a system of N-coupled oscillators with randomly distributed natural frequencies whose dynamics is described by a set of differential equations. Variations in number of oscillators and randomness imposed by distribution of natural frequencies induce changes in the synchronization process. In this work, a scale analysis on the number of oscillators and the dispersion parameter of natural frequencies of Normal, Cauchy-Lorentz and Laplace distributions was performed. It is shown in both cases that the synchronization, measured by the order parameter, obeys specifics scaling functions and, therefore, the number of oscillators and the order parameters are scalar invariants, i.e., they do not change qualitatively the synchronization. The proposed methodology can aid in the analysis of other parameters or models.
Otimização do tratamento de água cinza associando soluções aquosas de moringa oleifera e sulfato de alumínio
(Universidade Federal de Goiás, 2019-09-02) Rodrigues, Karen Campos; Sarmento, Antover Panazzolo; http://lattes.cnpq.br/4025685702530313; Paula, Heber Martins de; http://lattes.cnpq.br/6511292268901783; Paula, Heber Martins de; Abud, Celso Vieira; Ilha, Marina Sangoi de Oliveira
Given the growing demand for water in the world, approaches and/or actions are needed in order to reduce the consume and increase the demand, the water reuse is a viable alternative to increase the non-potable water demand in residences. The objective of this job is optimize the greywater treatment, from the washing machine, through the association of aluminium sulphate and Moringa oleifera seeds solutions. For this it was performed an experiment with the greywater from washing machine of a residence, dividing in 4 studies. It was realized the Study 1 of characterization of the flakes formed for each studied solution, which are Moringa oleifera extracted in aqueous calcium nitrate, aqueous calcium nitrate and aluminium sulphate. The Study 2 consisted in the jar-test experiment for each coagulant separately. Study 3 was later performed, which jar-test experiments for the association between aluminum sulphate and Moringa oleifera, with the combinations made through Central Composite Rotational Design as experimental planning. The data of this test was evaluated by the Response Surface Methodology. Lastly, in the Study 4 was made the desirability analysis, aiming to determine the optimal dosage for each coagulant. The parameters evaluated in the experiment was the pH, turbidity, sludge volume generated and total dissolved solids. The results of this study indicate that with the treatment that use the lower dosages of coagulant, being 20 ml L -1 of Moringa oleifera extracted in calcium nitrate and 1 ml L -1 of aluminium sulphate, is viable the greywater reuse, after the treatment, in toilet flush. It's still possible the water reuse in activities like car wash and other uses that require direct contact with the water, as long as added the steps of filtration, to reduce the total dissolved solids, and chlorination. For this coagulants dosages, the turbidity removal was 96,22%, the pH varied of 7,2 to 6,8, the total dissolved solids content was elevated of 360 mg L -1 to 589 mg L -1 , the chlorine content was reduced of 0,54 mg L -1 to 0,10 mg L -1 and the sludge volume generated was 48,7 cm3. The association of aluminum sulphate with Moringa oleifera extracted in aqueous calcium nitrate it is viable for coagulation treatment of greywater from washing machine, in order to reduce the dosages of each coagulant and attend standards criteria.
Uma contribuição ao estudo da guapeva (Pouteria Gardneriana Radlk): procedimento experimental, modelagem matemática e pós-processamento
(Universidade Federal de Goiás, 2019-08-12) Barbosa, Thaís Alves; Arruda, Edu Barbosa; http://lattes.cnpq.br/5969496186215144; Lobato, Fran Sérgio; http://lattes.cnpq.br/7640108116459444; Lobato, Fran Sérgio; Arruda, Edu Barbosa; Arouca, Fábio de Oliveira; Borges, Romes Antônio; Siqueira, Ana Paula Silva
The cerrado is configured with one of largest biomes in terms of representativeness and diversity in Brazilian territory. A wide variety of fruits and that presents applicability in different areas, as agriculture and medicine, can be found. Among these, the guapeva presents a large potential due to sweet taste, nutritional and bioactive, and applications in medicine field. Despite these characteristics, few studies considering this fruit can be found in the literature. In this contribution, this work aims to contribute in study of guapeva in terms of drying operation and characterization of produced flour with the bark of this fruit. For this purpose, a tunnel type dryer, in which experiments are performed to determine the parameters associated with the guapeva drying kinetic and parameters associated with the phenomenological model (effective moisture diffusivity and effective thermal conductivity). In this case, two inverse problems were proposed and solved by using the Differential Evolution algorithm. From the results obtained it was possible to observe a good concordance between the experimental and predicted results. In relation to physical-chemical analysis of the flour produced, it was possible to observe a good nutritional quality in comparison with other commercial flours. In this context, the product resulting from the drying process is configured as an alternative, from the nutritional point of view, to traditional products found in market.
Análise estática e dinâmica de pórticos planos com o uso da formulação corrotacional
(Universidade Federal de Goiás, 2018-10-22) Cunha, João Paulo Favoretto Braz da; Silva, Wellington Andrade da; http://lattes.cnpq.br/2449347153075493; Silva, Wellington Andrade da; Borges, Romes Antônio; Ribeiro, Paulo Marcelo Vieira
This research presents a survey of the corrotational kinematic description applied to the Finite Element Method for 2D beam element, based on the Euler-Benoulli beam hypothesis, with the purpose to handle the effects of geometric non-linearity in the behavior of structures. In order to complete this survey two Matlab\textregistered programs were implemented in the finite element method based on the kinematic description presented in this research. The first one was to static analysis, denominated PPNLG, and the second one to dynamic analysis, denominated PPNLD . In relation of the field of static analysis, the method of load displacement control was the cylindrical arch length method. To the dynamic analysis, the method used to solve the systems of nonlinear differential equations was the implicit direct integration method of Newmark. Both programs were successfully validated when comparing the results obtained in numerical examples with the results obtained by other bibliographies.
Projeto de sistemas de engenharia usando o Whale Optimization Algorithm
(Universidade Federal de Goiás, 2018-12-10) Mundim Filho, Ozanan Garcia; Lobato, Fran Sérgio; http://lattes.cnpq.br/7640108116459444; Lobato, Fran Sérgio; Abud, Celso Vieira; Souza, Davi Leonardo de
The formulation and solution of optimization problems configures a research line of great applicability, with emphasis in engineering systems design. Traditionally, the solution of these problems can be found by considering classical and metaheuristics methods. As an example of this last class we can cite a recent bio-inspired technique, the Whale Optimization Algorithm (WOA). This evolutive strategy consists in generating candidates to solve optimization problems through simulation of movements of humpback whales in search for food. However, this recent optimization technique requires new studies in order to improve its performance in problems more complex. Therefore, the present contribution aims to propose the Adaptive Whale Optimization Algorithm (AWOA), that consists in updating the internal parameters of WOA considering the concept of convergence rate and a cognitive social operator as alternative to generate potential candidates. The methodology is applied to mathematical problems and to engineering systems design. The results obtained demonstrate that the AWOA presented good performance in relation to WOA, but without increasing considerably the computational cost when compared to other evolutionary strategies.
Desenvolvimento de um algoritmo de otimização evolutivo auto-adaptativo para a resolução de problemas de otimização com variáveis mistas
(Universidade Federal de Goiás, 2018-12-10) Carvalho, Camila Campos; Lobato, Fran Sérgio; http://lattes.cnpq.br/7640108116459444; Lobato, Fran Sérgio; Abud, Celso Vieira; Souza, Davi Leonardo de
In last decades, evolutionary algorithm have been received considerable attention in different fields of science and engineering, with emphasis in engineering systems design. Despite at the large number of applications, these algorithms consider that parameters are constant during the search process, which may result in a search less efficient in design space. In addition, realistic problems are more complex in relation to the nature of project variables involved, i.e., these problems may present mixed variables (real (or continuous), integer, binary and discrete). In this contribution, it is proposed a new strategy to update the Firefly Algorithm (FA) parameters, as well as a new methodology to generate candidates. It is also proposed a strategy for the treatment of problems with mixed variables. An analysis of the parametric sensitivity is performed to understand how the choice of the values of each parameter of the FA could influence the method optimization process and still compromise the quality of the solution. The results obtained with the application of proposed methodology in mixed and real problems demonstrate that the performance of FA can be improved, in terms of convergence and computational cost, in relation to canonical algorithm.
Problema de carregamento em um único contêiner: abordagem exata e restrições práticas
(Universidade Federal de Goiás, 2018-11-27) Nascimento, Oliviana Xavier do; Queiroz, Thiago Alves de; http://lattes.cnpq.br/8041183668335400; Queiroz, Thiago Alves de; Junqueira, Leonardo; Silva, Sérgio Francisco da
This work presents an approach to solve the single container loading problem. The goal is to decide which items should be loaded inside the container in order to maximize the packed value. The approach is divided into two steps. The approach integrates integer programming and constraint programming models within an iterative scope. In addition, thirteen practical constraints are considered. These constraints are used to ensure complete shipment of items from the same customer, separation of conflicting items, priority conditions, vertical and horizontal cargo stability, items’ fragility, multi-drop situations, load balancing, that the resulting packing can be separated by cuts that go from one side to the other of the container without items being fragmented during the cutting, manual loading, separation of different customer’s items within the container, grouping of items and that items can be packed in different orientations. Mathematical formulations are developed for each one of them. The formulations are the main contribution of this research since there is a gap in the literature with respect to works that present mathematical formulations to practical constraints in the studied problem. Other contributions are the integration of integer programming and constraint programming models, the presentation of a new relaxation of integer programming to the problem, a new cut, and constraints for the reduction of symmetries. Instances from the literature are solved. The results showed that the largest losses of container’s volume are for the complete shipment constraint, while the smallest losses of container’s volume are for the grouping of items. The largest runtimes happen for the cargo vertical stability. The results also showed that the proposed relaxation, the constraints for symmetries breaking and the cut bring contributions with respect to the computational time and the number of instances solved to optimality.
Análise analítica e numérica de vigas casteladas com diferentes padrões geométricos
(Universidade Federal de Goiás, 2018-10-22) Melo, Pedro Henrique Pedrosa de; Silva, Wellington Andrade da; http://buscatextual.cnpq.br/buscatextual/ visualizacv.do?id=K4750483A1; Silva, Wellington Andrade da; Borges, Romes Antonio; Ferreira, Maurício Pina
The present paper deals with the main subjects related to castellated steel beams, initially showing a brief review of the history of emergence and use of the world, highlighting the characteristics that favored the growth of use and the difficulties of its use. The main failure modes are characterized, highlighting the analytical procedures available in the literature to circumvent them, in order to propose a calculation procedure for the design. The proposed procedure is evaluated through the experimental result of four surveys. The work also presents numerical modeling, using Finite Element Method (FEM), for beams available in the technical literature, in order to complement the analysis of beam behavior during loading and to verify the validity of the proposed numerical model, mainly in relation to the analysis criteria adopted in the numerical model, such as von Mises stress distribution, isotropic hardening and tensile stress behavior of the steel using the multilinear graph, also available in the technical literature. The validity allows the proposed beams, with Anglo-Saxon geometry, Litzka and Peiner, to have reliability of analysis of the model, and for the proposed loading the Anglo-Saxon beam obtained greater resistance, mainly due to the small distance between the holes and also the lowest overall width of the aperture. The results of the numerical models, via MEF, showed good precision when compared to the experimental results, showing that MEF is an extremely useful tool for nonlinear analysis, provided the model is properly calibrated. Another important result is the resistance values presented by the proposed analytical procedure, which presents a good approximation to the actual values of the experiment and also the resistance values obtained in the proposed numerical models, and can be adopted for the practical dimensioning of these beams.
Análise numérica de métodos empíricos do estudo da condutividade hidráulica
(Universidade Federal de Goiás, 2018-09-28) Gonçalves Filho, José Carlos Campos; Rabelo, Marcos Napoleão; http://lattes.cnpq.br/0067281135180613; Rabelo, Marcos Napoleão; Santos Filho, Tercio Alberto dos; Santee, Donald Mark
In the context of Agronomic and Environmental Sciences, the hydraulic conductivity K (µ) as a function of the humidity (µ) and granulometry, is especially important for the study and solution of practical problems related to irrigation, drainage , leaching of nutrients and pollutants, slope stability, problems related to soil compaction in general. Studies will be carried out that stipulate the hydraulic conductivity K (µ) from the particle size distribution and moisture content for certain types of soil, with the particle diameter as the main parameter to obtain the same. One of the advantages in this methodology is the reduction of laboratorial costs and the reduced time when compared to tests to obtain these physical indexes. The state of the art in empirical validation has produced numerical models for simulation description of physical indices. Using experimental methodologies, we will use these models for the validation and subsequent analysis of results for soils obtained at UFCat. The first part of the work will be devoted to the study of statistical models, which relate the behavior of the hydraulic coef cient with the soil granulometry. For this part of the work, the main referencewill be the article (SALARASHAYERI; SIOSEMARDE, 2012). The models that will be used in this dissertation were obtained in (SALARASHAYERI; SIOSEMARDE, 2012), where the authors, through 25 samples of sandy soil extracted characteristics of the hydraulic conductivity. In the present case, laboratory tests have shown that the characteristic of the analyzed soil approaches a clayey behavior see (GONçALVES-FILHO et al., 2017b), (GONçALVES-FILHO et al., 2017a). To overcome this problem we will use the graphs generated from experimental analyzes made by means of humidity sensors, to calibrate statistical models. In the second part of the work, a study will be done, through models that relate the hydraulic coef cient to the soil moisture. For this part the reference (GENUCHTEN, 1980) will be used. In (GENUCHTEN, 1980), analytical models describing the relationship between hydraulic coefIcient, moisture and piezometric level were obtained. The theoretical models will be validated by comparing the theoretical curves and the experimental data acquired through sensors. As a complementary part of the work, numerical simulations will be done to analyze the behavior of the hydraulic coefIcient, with the different models approached.
Aplicação dos mapas auto-organizáveis associado ao monitoramento da integridade estrutural baseado na impedância eletromecânica
(Universidade Federal de Goiás, 2018-07-04) Durval, Michael dos Santos; Mora Júnior, José dos Reis Vieira de; http://lattes.cnpq.br/2479225716217997; Tsuruta, Karina Mayumi; Stoppa, Marcelo Henrique; Moura Júnior, José dos Reis Vieira de
Structural Health Monitoring (SHM) is a very cost-effective technique to reduce costs, increase life-cycle, and improve the performance of engineering structures. The impedancebased methodology uses the electromechanical behavior of piezoelectric materials (PZTs) to detect structural anomalies and damages. This technique uses high frequencies and excites the local modes, thus providing the monitoring of any change of the structural mechanical impedance in the region of influence of PZT. From the variation of the impedance signals, it can be concluded whether or not there is a damage. Artificial neural networks (RNA) are part of a broad concept called artificial systems. The foundation of neural networks is associated with the functioning of the human brain, which after training has the ability to perform associations. This science has great applicability in the solution of artificial intelligence problems, through the modeling of systems that use connections that make it possible to simulate the human nervous system. This work uses Kohonen’s self-organizing maps (SOM) associated to SHM based on electromechanical impedance for the detection and classification of damages in an aluminum beam. Based on the system under analysis, the network was trained to five different failure and severity positions. Through the neural network model of self-organizing maps, the network provided 30 maps as answers to the training and learning process. With this, it was realized qualitatively based on the concentration of energy of the maps that the grouping and classification of the different conditions of damages in which the engineering structure was submitted, happened with success. In order to establish a quantitative analysis proving the potential of the SOM network, the Hamming distance formula was applied, in which the results confirmed its accuracy.
Dimensionamento de equipes de trabalho por meio de modelos probabilísticos
(Universidade Federal de Goiás, 2018-05-18) Freitas, Christiano Michel Fernandes; Moura Júnior, José dos Reis Vieira de; http://lattes.cnpq.br/2479225716217997; Moura Júnior, José dos Reis Vieira de; Rabelo, Marcos Napoleão; Soares, Júlio Cesar Valandro
This work proposes the modeling of a production system with three manufacturing units, in order to allow the optimal dimensioning of maintainers and the accomplishment of a sensitivity analysis that allows to evaluate the reliability of the obtained results. A Quasi-Birthand- Death (QBD) process is used to model the productive units, and through infinitesimal generators, the input probabilities for the developed code are obtained. Organizations usually define their supporter teams empirically, which can compromise organizational strategies. Thus, the code offers assistance in the decision making of these professionals. Thus, three production units X, Y and Z were modeled and the minimum dimensioning of maintainers that each unit had to be performed. Thus, the X unit with two maintainers provides a 70% probability of remaining in operation, the Y unit with three provides 76%, and finally, the Y unit with only one maintainer allows an 80% chance of remaining in operation. Bymeans of the sensitivity analysis, it was noticed thatwhen disturbing the infinitesimal generator the values of probability of operation tend to approximate to 100% whereas a maintainer is added, however, when the fourth maintainer is added, there is little variation in the system. However,when the system is stressed by the growth of the randomvariable t, the reliability of the results tends to decrease, whereas with a maintainer, the probability of functioning falls considerably over time, and in contrast, with four maintainers, the permanence of operating state tends to be distant.
Um estudo comparativo entre soluções aplicadas a um problema de flow line misto
(Universidade Federal de Goiás, 2018-05-17) Martins, Jeferson Silva; Moura Júnior, José dos Reis Vieira de; http://lattes.cnpq.br/2479225716217997; Moura Júnior, José dos Reis Vieira de; Fuchigami, Hélio Yochiriro; Queiroz, Thiago Alves de
This paper presents the Mixed-Model Flow Line problem for Production Scheduling. Production problems have been vastly studied given their usability in all kind of assembly lines and its production in the industry worldwide. The problem processes jobs grouped by families in stations of machines seeking for the best sequencing the families can provide to be produced in the processing time (Makespan). In this work, a bibliographic review was performed to support the study, looking different methods and problems that encompass the Mixed-Model Flow Line in the literature showing its importance towards the industrial and scientific environment. The Mixed-Model Flow Line problem was solved through optimization techniques: An integer lienar programming inGUROBI, Lagrangian Relaxation and Genetic Algorithm. The processing times and demands are randomly generated for each instance. Finally, the results obtained in the techniques used for the problem were compared to each other.
Estudo e caracterização de componentes confeccionados por manufatura aditiva
(Universidade Federal de Goiás, 2018-04-02) Rezende, Stéfany Mayara Ferreira de; Stoppa, Marcelo Henrique; http://lattes.cnpq.br/1532505326645535; Pituba, José Júlio de Cerqueira; Santee, Donald Mark
There are several techniques used for the manufacture of three-dimensional models, but due to their ease of use, material extrusion has been widely applied in speciﬁc areas, since such as engineering as personal use. Such factors indicate that in the coming years many of the everyday plastic products commonly produced by conventional methods will be replaced by home printed objects in order to minimize costs and customization. Thus, knowing the inﬂuence of the process parameters is fundamental for the good performance of the products made by this technology. Thus, this work is dedicated to the study of the mechanical properties of parts constructed by material extrusion and the inﬂuence of parameters of the material and the printing process on the ﬁnal characteristics of the produced object. A brief review of the literature is carried out in order to know the mechanical properties already identiﬁed and which methods are most used. It has been identiﬁed that the mechanical properties of the printed pieces are signiﬁcantly affected by the printing orientation and airgap parameters. An experimental approach is used, aiming to evaluate the inﬂuence of parameters, shape and ﬁll percentage, on the mechanical strength of the made objects. In addition, an initial and introductory study was carried out in order to analyze the functional characteristics of a prosthesis made by additive manufacture. The accomplishment of the same, aims to identify the limitations of the device and to provide future improvements.
Uso das cadeias de Markov associado ao monitoramento da integridade estrutural baseado em impedância eletromecânica
(Universidade Federal de Goiás, 2018-05-02) Bento, João Paulo Moreira; Moura Júnior, José dos Reis Vieira de; http://lattes.cnpq.br/2479225716217997; Steffen Júnior, Valder; Borges, Romes Antônio
There are several problems that can occur in components exposed to constant use and subjected to wear among the different types of structural components. Thus, in the last years it has been developed techniques able to monitor the health of the structures. In the last decades many non-destructive techniques have started to be used, among them we can mention the method of electromechanical impedance. This work proposes to present in the bibliographic review some basic concepts related to the main topics related to SHM (Structural Health Monitoring), such as smart materials, the different techniques, damage metrics and impedance analyzers. It will also be approached some techniques of classic optimization (random search) and bioinspired (bee colony algorithm and ant colony algorithm) that can be used to perform electromechanical impedance signals between damaged and non-damaged structures. Finally, it is presented the subject of Markov chains, a stochastic process, which a future state depends only on the present state and not on the other past states. The dissertation proposal is a case study (LEGO System) that aims to apply the concepts of electromechanical impedance, optimization and Markov chains for the monitoring of structural health in a defined system, and with this result, be able to provide data for a possible failure prediction. Concluding, it can realize the potentiality of the Markov chains associated to the electromechanical impedance method for monitoring and predicting future states.
Sistema robótico do tipo exoesqueleto para reabilitação de membro superior
(Universidade Federal de Goiás, 2018-03-29) Ferreira, Eliezer Pires; Stoppa, Marcelo Henrique; http://lattes.cnpq.br/1532505326645535; Rabelo, Marcos Napoleão; Silva, Fernando Kennedy da; Costa, Vaston Gonçalves da; Pituba, José Julio de Cerqueira
Factors that cause loss of total or partial movement of upper limbs are common as neuropathies (diseases graves in the nerve), myopathies (diseases affecting the muscle), trauma and stroke. Even so, motor and functional patients return after the stroke, patients still advanced functional mobility difficulties that enable personal care and normal life. In many cases, a loss of movement can be reversed, or at least minimized, through rehabilitation exercises, but very slowly and almost always costly. The high price of assistive technology equipment from inactive communities for people with disabilities, especially in underdeveloped countries. Aiming for a superior limb rehabilitation, this paper presents a model and development of an upper limb exoskeleton prototype with two degrees of freedom, low cost, with a structure made of printer 3D. The study presents several existing models, and exhibits a mathematical model of an exoskeleton for flexion and extension movements, with simulation and subsequent prototyping.
Modelagem e simulação de dispositivo manual auxiliar para mobilidade de cadeirantes com paraplegia por lesão medular
(Universidade Federal de Goiás, 2018-02-23) Lino, Sémebber Silva; Rabelo, Marcos Napoleão; http://lattes.cnpq.br/0067281135180613; Stoppa, Marcelo Henrique; http://lattes.cnpq.br/1532505326645535; Stoppa, Marcelo Henrique; Costa, Vaston Gonçalves da; Espinosa, José Waldo Martinez; Moura Júnior, José dos Reis Vieira de; Bittar, Thiago Jabur
Extension or flexion movements of the body in a healthy individual are routine physical activity in daily life, necessary for its autonomy and independence.Injuries to the spinal cord and brain are the main causes of paraplegia, which makes it impossible for human locomotion with autonomy. The use of a wheelchair will help them into your daily horizontal mobility. But the possibility of using an orthotic device to allow it to increase the amplitude of the movements of extension or flexion will help in maintaining your bone density, improving your blood circulation and enlargement of muscle tone, involving tension in muscles, arteries and other tissues organic well as excessive involuntary reflex. Therefore, this study aims to present a mathematical model to describe the trajectory of nodes corresponding to the movable joints and upper extremity of a low cost orthosestic device, of the exoskeleton type, to be coupled in the wheelchair, using computer simulation to determine the variation of positions and velocities of these joints associated with the articulations of the hip and lower limbs of the paraplegic wheelchair user, when performing extension or flexion movements of the body segments, besides the simulation of a prototype developed in CAD. As for the main results of the research, first, there is the trajectory of the nodes with respect the mobile joints and upper end using the representation of Denavit-Hartenberg, generated graphically by numerical and computer simulation, in order to validate and make feasible the mechanical construction of the device. Then, as the variation of the positions and velocities of motor gasket associated with the user’s knee joint device, has its graphical representation plucked by multistep interactive Runge-Kuta 4th Order, using the Lagrange equations for numerical and computational simulation of the transmission system drive, with the application of a torque on the crank of the robotic mechanism proposed, thus confirming its usability, reliability and security. Finally, the development of a 3D virtual prototype device CAD. Therefore, the preparation and provision of this manual orthotic device developed to assist in the vertical mobility of the paraplegic with spinal cord injury, will improve physical, psychological health, functional independence and daily well-being, and helping them in their autonomy to support on the feet.

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