Adilson Rodrigues da Costa

A multi-objective green UAV routing problem

Introduce a new time-dependent UAV heterogeneous fleet routing problem.Consider several objective functions and respect drones operational requirements.Design a MILP model in order to find sets of non-dominated solutions.Consider a model able to tackle multi-layer scenarios with package exchanging points.Integrate UAV into the new concepts of mini/microgrid systems inside smart cities. This paper introduces an Unmanned Aerial Vehicle (UAV) heterogeneous fleet routing problem, dealing with vehicles limited autonomy by considering multiple charging stations and respecting operational requirements. A green routing problem is designed for overcoming difficulties that exist as a result of limited vehicle driving range. Due to the large amount of drones emerging in the society, UAVs use and efficiency should be optimized. In particular, these kinds of vehicles have been recently used for delivering and collecting products. Here, we design a new real-time routing problem, in which different types of drones can collect and deliver packages. These aerial vehicles are able to collect more than one deliverable at the same time if it fits their maximum capacity. Inspired by a multi-criteria view of real systems, seven different objective functions are considered and sought to be minimized using a Mixed-Integer Linear Programming (MILP) model solved by a matheuristic algorithm. The latter filters the non-dominated solutions from the pool of solutions found in the branch-and-bound optimization tree, using a black-box dynamic search algorithm. A case of study, considering a bi-layer scenario, is presented in order to validate the proposal, which showed to be able to provide good quality solutions for supporting decision making.

Discontinuity Detection in the Shield Metal Arc Welding Process

This work proposes a new methodology for the detection of discontinuities in the weld bead applied in Shielded Metal Arc Welding (SMAW) processes. The detection system is based on two sensors—a microphone and piezoelectric—that acquire acoustic emissions generated during the welding. The feature vectors extracted from the sensor dataset are used to construct classifier models. The approaches based on Artificial Neural Network (ANN) and Support Vector Machine (SVM) classifiers are able to identify with a high accuracy the three proposed weld bead classes: desirable weld bead, shrinkage cavity and burn through discontinuities. Experimental results illustrate the system’s high accuracy, greater than 90% for each class. A novel Hierarchical Support Vector Machine (HSVM) structure is proposed to make feasible the use of this system in industrial environments. This approach presented 96.6% overall accuracy. Given the simplicity of the equipment involved, this system can be applied in the metal transformation industries.

Texturização por Laser ND: YAG e comportamento tribológico de um recobrimento de cromo

A regular spaced array (texture) consisting of holes produced by pulsed Nd:YAG laser was designed in order to improve lubricant conditions of chromium eletro deposited layer upon mild steel. This surface textured was designed so that any hole behaves as an additional lubricant reservoir in boundary lubricant conditions. Metallographic and topographic analysis were performed and an analitical interpretation was proposed to describe tribological behaviour of this laser patterned (regular holes distribuition) and conventional (no laser treated) coatings. Tribological tests were performed accordingly to pin-on-disc procedure. A relevant increase in scuffing resistance was observed for texture coating: three times compared with conventional eletro deposited chromium layer. Better behaviour in wear tests (loss of mass) was also observed.

Evolução das cores RGB : uma ferramenta digital para monitorar mudanças visuais em pigmentos irradiados por pulsos de laser infravermelho.

Oxidos de ferro (goethita e hematita) pulverizados foram irradiados com pulsos laser objetivando verificar o resultado da interacao desses pos com a radiacao infravermelha concentrada em pulsos de curta duracao e altamente energeticos. Esses experimentos se justificam diante da utilizacao desses pos, em obras de arte, como pigmentos, desde as epocas mais remotas. Na atualidade, tornou-se frequente recorrer a pulsos laser como ferramenta de limpeza de obras de arte, o que justifica a necessidade do desenvolvimento de conhecimentos relacionados a interacao laser-pigmentos. Evitar danos as obras de arte, recentes ou nao, e uma exigencia inevitavel. Os resultados mostraram que os pulsos laser Nd:YAG fornecem energia suficiente para promover, instantaneamente, mudancas quimicas e estruturais nos pigmentos minerais estudados. Material vitrificado (amorfo) foi identificado nas amostras irradiadas e sua formacao deveu-se a solidificacao ultra-rapida ocorrida no locais onde a energia disponibilizada pelos pulsos laser foi suficiente para fundir as particulas do po. Em consequencia das mudancas quimicas e estruturais induzidas, houve alteracao da cor original do material irradiado. Essas alteracoes cromaticas foram quantificadas por intermedio de um metodo desenvolvido para tal finalidade e que e baseado na variacao da intensidade das componentes RGB das cores digitais.

Validation of a simplified computer simulation method for plastic forming of metals by conventional tensile tests

This work was developed in order to validate a simplified computer simulation method for application in the drawing processes. The results of tensile tests on AISI 1004, AISI 1020 steel and copper were compared to those of computer simulations performed using the Deform-3DTM software. Each specimen was assumed to be an elasto-plastic material and was meshed with 50,000 finite elements. Youngs modulus and Poissons ratio were the only material properties considered in the elastic region; the parameters of Hollomon’s equation were used in the plastic region up to constriction. A strain rate of 1x10-3 s-1 was applied during the simulations. In the plastic region, up to the point of constriction, the curves obtained from the simulations showed reasonable correspondence to those determined from physical testing. However, the former diverged from the latter in the elastic and elastic-plastic transition regions. This divergence indicates that microstructural factors may have a greater influence in the transition region than in the plastic region. Moreover, the correlation obtained in the plastic region indicates that the proposed method has the potential to be applied in drawing processes.

Soldagem do aço inoxidável AISI 316 com laser à fibra de alta potência: influência dos parâmetros operacionais na micro dureza e na susceptibilidade à corrosão eletrolítica dos cordões de solda

This paper addresses an evaluation of the influence of operational parameters used in the AISI 316 stainless steels laser welding process. The results of the welding experiments performed with parameters adjusted to a variety of situations were evaluated taking into account the power density available and the interaction time of the laser beam with the base metal. These evaluations were based on the results of microhardness and the electrolytic corrosion tests of the solders, assisted by the macrography of the weld bead. It was sought to emphasize correlations between selected operating parameters and the results obtained with weld beads, measuring their width and depth. It was concluded that the proper choice of operating parameters is fundamental to the guarantee of quality of the weld beads. Besides that, a quick method of evaluation of weld beads susceptibility was validated.

Abrasive Wear: Design of Experiment (DOE) for Determining the Wear on Crowns Used by Drilling Companies for Mineral Surveys

Currently companies seek performance improvement for equipment and components, and an important factor that influences performance is wear. The objective of this study was to demonstrate the applicability of a methodology that was developed using literature, field research, brainstorming, optical microscopy, statistical analysis.Wear tests for drilling crown samplesfor the production process were performed. - The crown’s chemical composition was analyzed to see if it was appropriate for the soil’s mineral lithology. Having done this, a statistical analysis was made. using Minitab 16 software, specifically applying DOE (2Kfactorial) technique. With the statistical result, a prototype was produced and subjected to a wear test for analysis of material loss compared to crowns having a better performance.Thus, the conclusion reached was that the planning process improves withthis experimental probing, which helps to identify and correct controllable factors.

Desenvolvimento de modelo de seleção de materiais metálicos aplicando uma abordagem logística - o caso de empresas do setor minerometalúrgico.

Logistics has become a decisive process for the survival of companies. Logistic aspects are responsible for the flow of materials and information from the supplier to the consumer, and have a direct impact on the performance of companies, as well as on the costs of the products and services they offer. This is enough to justify the addition of logistic aspects as tools for analysis and material selection. This work aims at presenting the development of a model for the selection of metallic material, which considers the logistic aspects on the decision process. For this reason, we have used an adaptation of the PERT net (Program Evaluation and Review Technique), relating indicators of variables from material selection with those from logistics. For the purpose of validation, we then implemented the model and presented it to experts of the mining-metallurgical sector. These experts had previously reported a lack of management systems that support the selection process relating to material and logistic information. As a result, they considered the proposed model to be an important instrument for undertaking managerial decisions.

Caracterização microestrutural de um provável fragmento do meteorito Itutinga.

O Museu de Ciencia e Tecnica da Escola de Minas da Universidade Federal de Ouro Preto possui um fragmento de meteorito metalico com 110,76g denominado Itumirim, encontrado proximo a Itutinga, cidade do interior de Minas Gerais, distante 228km de Belo Horizonte. Realizando-se analises ao microscopio eletronico de varredura (MEV), determinou-se a classificacao estrutural do fragmento Itumirim como octaedrito medio, Om. As fases mineralogicas presentes foram determinadas recorrendo-se as analises com o detector de energia dispersiva de raios X (EDS) acoplado ao MEV e com o espectrometro Mossbauer miniaturizado, MIMOS II. Esses resultados somados a correlacao existente entre classificacao estrutural e quimica permitiram classificar o fragmento Itumirim como pertencente ao grupo IIIAB, a mesma classificacao do meteorito Itutinga.

Influence of texturing by laser Nd:YAG in the tribological behavior of a chromium electro-plated coating on carbon steel

A regular spaced array (texture) consisting of holes produced by pulsed Nd:YAG laser, being designed in order to improve lubricant conditions of chromium electro deposited layer upon mild steel. This textured surface was designed so that any hole behaves as an additional lubricant reservoir under boundary lubricant conditions. Metallographic and topographic analysis were performed and it was proposed an analytical interpretation to describe tribological behavior of this laser pattern of regular holes distribution, for the conventional (no laser treated) coating. Tribological tests were performed according to pin-on-disc procedure. A relevant increase in scuffing resistance was observed for texture coating: three times higher when compared with conventional electro plated chromium layer. Better behavior in wear test (loss mass) was observed.A regular spaced array (texture) consisting of holes produced by pulsed Nd:YAG laser, being designed in order to improve lubricant conditions of chromium electro deposited layer upon mild steel. This textured surface was designed so that any hole behaves as an additional lubricant reservoir under boundary lubricant conditions. Metallographic and topographic analysis were performed and it was proposed an analytical interpretation to describe tribological behavior of this laser pattern of regular holes distribution, for the conventional (no laser treated) coating. Tribological tests were performed according to pin-on-disc procedure. A relevant increase in scuffing resistance was observed for texture coating: three times higher when compared with conventional electro plated chromium layer. Better behavior in wear test (loss mass) was observed.