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Industrial equipment is usually high in cost. Design engineering needs to specify fuses that have the role of protecting the main parts of the equipment. The aim of this work is to identify the reason that led to a high number of fractures in mechanical fuses of a rolling mill and suggest improvements to fix the problem. Two components were analyzed: one that failed and one that was used inside the equipment but did not fail. According to their datasheet, the components are made of quenched and tempered type 4140 (UNS G41400) steel. Chemical analysis of the fuse was performed using x-ray fluorescence. Microstructural and fractographic aspects were investigated by optical and scanning electron microscopy. The existence of surface cracks is investigated by liquid penetrant test. Tensile analyses in the component are made using analytical and numerical methods. Numeric analyses are performed by the finite element method. The chemical analysis is in agreement with that expected for type 4140. The fractographic analysis shows intergranular brittle fracture. No surface cracks are found by the liquid penetrant, and no evidence of fatigue mechanism fracture is found the fractographic analysis. All results indicate that the component fractured due to the action of overload. By comparing the numerical and analytical methods, it is possible to identify that the stress concentration in the fuse analyzed results has a value of 9.44% lower when the analytical method is used. It is possible to conclude that the analytical method causes an error in the design, which was not covered by the safety factor because mechanical fuses did not use a safety factor in their projects. Increasing the radius of stress concentration can compensate the error, without requiring dimensional changes in the component. A new component is manufactured according to this concept, which is in operation without any issues.

EXEMPLIFYING THE USE OF MACRO ELEMENTAL MAPPING BY XRF (MA-XRF) SCANNING IN FORENSIC INVESTIGATION OF ARTWORKS. This work exemplifies the potential of employing macro elemental mapping by XRF (MA-XRF) scanning in the forensic investigation of artworks. The results of the investigation of two artworks of different styles and periods are presented and discussed. The images provided by MA-XRF scanning have information about the elemental distribution, which is related to pigments used in the artwork. These images bring different information such as: if there are underlying paintings; if a given pigment was used for the purpose of restoration or in the creation. Therefore, through the images, it is possible to obtain information, which refers to the process of creating the artwork and the history of conservation and restoration. Through the results, it was possible to verify that the two artworks are probably false because they present anachronistic pigments with the supposed period of creation. The analyzes were performed using a portable MA-XRF scanning system, and in addition to presenting the utility of the instrument in these investigations, the work also presents possibilities to explore the MA-XRF data through multivariate statistical analysis and image correlation.

This work aims to characterize the elemental concentrations of two banana types gold and silver. In both were analyze in the pulp and peel by X-Ray Fluorescence technique. The results showed that the elements in both types are more concentrated in the peel than in the pulp. In addition, it was also observed that the normalization of the peel and pulp concentrations for the elements K, Fe, Zn, Br, Rb, and Sr is higher in the silver banana compared to the gold banana. The results indicate that banana peels can be used to supplement nutritional deficiencies. The work also demonstrates the potential that X-Ray Fluorescence has in investigation of elemental composition of foods. As the technique has easy instrumentation and data interpretation, it can be implemented as a routine in the investigation of the elemental composition of foods. In addition, the technique has the advantage of carrying out in situ analyzes by portable instruments. These in situ investigations can even be applied to make quality control of bananas at the time of harvest. Este trabajo tiene como objetivo caracterizar las concentraciones elementales de dos tipos de banano, oro y plata. Ambos tipos fueron analizados, en la pulpa y en la piel, mediante la técnica de Fluorescencia de Rayos X. Los resultados mostraron que los elementos en ambos tipos de banano están más concentrados en la piel que en la pulpa. Además, también se observó que la normalización de las concentraciones de cáscara y pulpa para los elementos K, Fe, Zn, Br, Rb y Sr es mayor en el banano plateado que en el banano dorado. Los resultados indican que las cáscaras de plátano se pueden utilizar para suplir las deficiencias nutricionales. El trabajo también demuestra el potencial que tiene la fluorescencia de rayos X en la investigación de la composición elemental de los alimentos. Debido a su fácil instrumentación e interpretación de datos, la técnica se puede implementar de forma rutinaria en la investigación de la composición elemental de los alimentos. Además, la técnica tiene la ventaja de realizar análisis in situ utilizando instrumentos portátiles. Estas investigaciones in situ pueden incluso aplicarse para controlar la calidad de los bananos en el momento de la cosecha. Este trabalho tem como objetivo caracterizar as concentrações elementares de dois tipos de banana, ouro e prata. Ambos os tipos foram analisados, na polpa e na casca, pela técnica de Fluorescência de Raios-X. Os resultados mostraram que os elementos de ambos os tipos de banana estão mais concentrados na casca do que na polpa. Além disso, também foi observado que a normalização das concentrações de casca e polpa para os elementos K, Fe, Zn, Br, Rb e Sr é maior na banana prata em relação à banana ouro. Os resultados indicam que as cascas de banana podem ser utilizadas para suprir deficiências nutricionais. O trabalho também demonstra o potencial que a Fluorescência de Raios-X tem na investigação da composição elementar de alimentos. Por possuir fácil instrumentação e interpretação dos dados, a técnica pode ser implementada rotineiramente na investigação da composição elementar dos alimentos. Além disso, a técnica tem a vantagem de realizar análises in situ por instrumentos portáteis. Essas investigações in situ podem até ser aplicadas para fazer o controle de qualidade da banana na época da colheita.

Neste trabalho apresentamos uma atividade de baixo custo que visa a investigação da força de arrasto, que atua na geometria de um disco, através das oscilações amortecidas de um sistema massa-mola. Utilizando discos de papelão de diferentes raios e controlando a massa do sistema oscilatório, mantendo-a fixa, estudamos a influência da variação exclusiva da magnitude da força de arrasto na dinâmica desse sistema, por meio da variação do raio do disco, mantendo todos os outros parâmetros acessíveis do sistema fixos. A técnica de vídeo-análise é utilizada para rastrear o movimento do sistema, levando o estudante a investigar e a extrair conclusões acerca da dependência funcional da força de atrito viscosa com o raio do disco, bem como a obter a constante elástica da mola e uma estimativa para a espessura dos discos. In this work we present a low-cost activity that aims to investigate the drag force, which acts on the geometry of a disc, through the damped oscillations of a mass-spring system. Using cardboard disks of different radii and controlling the mass of the oscillatory system, keeping it fixed, we studied the influence of the exclusive variation of the magnitude of the drag force on the dynamics of this system, by varying the radius of the disk, keeping all the others fixed system accessible parameters. The video analysis technique is used to track the movement of the system, leading the student to investigate and draw conclusions about the functional dependence of the viscous frictional force with the radius of the disk, as well as to obtain the spring elastic constant and an estimate for the thickness of the disks.

In this work, a painting suspected of counterfeiting was analyzed using the synchrotron-based scanning macro X-ray fluorescence (MA-XRF) technique. The canvas has erasures including a signature erasure; however, some visible numbers indicate that the artwork may be from the 17th century. Through the studies' elemental maps, Cl-K and Ca-K were observed, which allowed us to reconstruct the signature present in the painting. Elemental maps of Ba-K, Ti-K, Fe-K, Zn-K, and Pb-K were also obtained from the painting, which made possible to visualize how the pigments based on these elements were used in the creative composition of the painting. In addition to the signature region, a region of the painting with dimensions of approximately 120 mm × 120 mm was investigated by synchrotron radiation induced MA-XRF, while keeping a high spatial resolution and elemental sensitivity. The measurements were carried out at the D09B micro-XRF beamline of the Brazilian Synchrotron Light Laboratory (LNLS), part of the Brazilian Center of Research in Energy and Materials, in Campinas Brazil. The painting was also investigated by SEM-EDS, and FTIR techniques. Those results, in addition to the supporting elemental maps, allowed additional information to be obtained, such as the binders used on the painting.

Resumo Neste trabalho realizamos uma abordagem didática de aspectos relacionados ao geomagnetismo e como esses aspectos podem ser influenciados pela ação do vento solar. A carência de textos didáticos que promovam explicações em termos de conceitos de física básica foi a principal motivação para esse trabalho. Iniciamos com uma discussão histórica sobre o estudo do magnetismo que culminou na conhecida teoria do dínamo para explicar a origem do campo magnético terrestre, na qual mostramos a possiblidade de abordar este assunto em cursos de eletricidade e magnetismo. Apresentamos também dois cenários para a magnetosfera terrestre, com o intuito de modelar a interação do vento solar com a magnetosfera, em que representamos tal interação por meio da superposição dos campos de dois dipolos magnéticos. A seguir mostramos a possiblidade de discutir o movimento das cargas provenientes do vento solar ao redor da Terra, na região da magnetosfera, utilizando a segunda lei de Newton e a força de Lorentz, discutindo assim a formação de anéis de cargas em movimento e dos cinturões de Van Allen. Finalmente apresentamos um simples argumento, baseado no modelo apresentado, para a deformação da magnetosfera, para explicar a limitação na quantidade de anéis e cinturões que envolvem o nosso planeta. Abstract In this work we perform a pedagogic approach to aspects related to geomagnetism and how they can be influenced by the action of the solar wind. The lack of didactic textbooks that promote explanations in terms of basic physics concepts is the main motivation for this work. We begin with a historical discussion about the study of the magnetism that culminated in the well-known dynamo theory which explains the origin of the Earth's magnetic field, where we show the possibility to treat this subject in classes of electricity and magnetism. We also present two scenarios for the Earth's magnetosphere, in order to model the interaction of the solar wind with the magnetosphere, where we represent such action by superposing the fields of two magnetic dipoles. After we show the possibility of discussing the movement of charges coming from the solar wind around the Earth, in the region of the magnetosphere, using Newton's second law and the Lorentz force, where we discuss the formation of moving charged rings and the well known Van Allen belts. Finally, we present a simple argument based on the presented model, for the deformation of the magnetosphere, to explain the limitation in the amount of rings and belts that surround our planet.

In this paper, a European black Japanned piece of furniture (dated to approximately 1860) was analyzed by XRF, Raman spectroscopy and FT-IR techniques. The analyses detected pigments such as vermilion/cinnabar [HgS], Massicot [PbO], lamp black [C] and green earth [K[(Al,FeIII),(FeII,Mg)](AlSi3,Si4)O10(OH)2], which were possibly dissolved in gum arabic. The analyses also determined that the metallic ornaments consist of a brass alloy with traces of gold and that gold was also used in some golden regions of the polychrome. The results obtained assisted restorers in choosing suitable intervening procedures and contributed to a better understanding of the cupboard manufacturing process.

The experiment was carried out in the Experimental Area of ​​the Plant Genetic Improvement Sector of the Agricultural Sciences Center of the Federal University of Alagoas (SMGP-CECA-UFAL), in the year 2013, where periods of control and weed coexistence of sweet potatoes were evaluated. The experimental design was carried out in randomized blocks in the 3 x 14 factorial scheme with three replications, with three sweet potato genotypes in 14 periods of interference, and distributed in seven control periods (0, 10, 20, 30, 40, 50 and 60 days after planting - DAP), from which the weeds were controlled, and seven coexistence periods, from which the weeds coexisted with the crop. The evaluations consisted of sweet potato genotype shoot samplings at 30, 60, 90, and 120 days after planting (DAP), using one working area plant per plot in each evaluation stage. In the determination of the leaf area, a mechanical integrator was used, and to obtain the shoot dry mass, the material was taken to a forced air circulation oven at 65 ºC for 72 h, with subsequent weighing. According to the results, it can be observed that, in the coexisting treatments, there was a significant reduction in the shoot growth rates, in comparison to the treatments in which the weeds were controlled, especially the reduction of the leaf area at 120 DAP, where clone 6 and Sergipana showed a reduction of 89.0% and 88.0%, respectively. As for Clone 14, this reduction occurred at 90 DAP, at about 52.0%, which was less expressive, whereas in relation to the shoot dry mass, clones 6, 14, and the Sergipana variety showed a reduction at 120 DAP of 86%, 51%, and 46%, respectively.

In this paper, nine beads from excavations in the Valongo Wharf, located in the harbor area of Rio de Janeiro, Brazil that were utilized as ornaments by Africans and Afrodescendants during the 19th century were analyzed by Raman and X-Ray Fluorescence (XRF) spectroscopy. All samples in the analysis showed Raman spectra with two bands of maximum intensity around 1000 and 500 cm−1 related to the maximum stretching (νmax) and bending mode (δ), respectively, of the tetrahedral network of the SiO4 present in the glass matrix. However, there is variation in the intensity and position of the bands that are directly associated with the burning process and the raw material utilized in the manufacture of the beads. Based on the polymerization index (Ip = A500/A1000), it is possible to relate these two parameters. By establishing a correlation among the Ip and the νmax band, the beads were classified into groups. The results reveal that the beads’ base paste exhibits differences, allowing their classification into groups according to the manufacturing process. Based on the combination of the elemental characterization and Raman spectroscopy results, it was also possible to conclude that European and Asian countries are the possible origins of the beads.

In this study, twenty samples of clay smoking pipes excavated in an 18km(2) area between the Macacu and Caceribu rivers, in the municipality of Itaboraí, Rio de Janeiro, Brazil were analyzed by FT-IR technique. The samples, excavated in different archeological sites of the region, are dated between the seventeenth and the nineteenth centuries and are part of the material culture left by Africans and African descendants that lived in the complex. FT-IR analyses and complementary SEM-EDS studies showed that the clay paste used in the manufacture of smoking pipes, mostly handcrafted, is composed of quartz, feldspar, phyllosilicates and iron oxides. Multivariate statistical tests (PCA) were applied to FT-IR data to assess the interactions between the archeological sites. The results indicated that one archeological site - Macacu IV - is greatly related to the other sites. The results obtained have helped archeologists and anthropologists in better understanding the manufacturing process employed in ancient ceramic artifacts produced during the period of colonial Brazil.

In this study, samples were taken from the sculpture of Our Lady of Sorrows and analyzed by Raman spectroscopy and FT-IR. This sculpture has been dated to the early eighteenth century. Samples were also examined using optical microscopy and Energy Dispersive Spectroscopy (EDS). Based on chemical analysis, the pigments vermilion [HgS], massicot [PbO] and azurite [Cu3(CO3)2(OH)2]were found in the sculpture polychrome. The results indicate that the green polychrome of the sculpture's mantle comes from the blending of massicot and azurite. Because the literature reports that the mantle of the Our Lady of Sorrows sculpture is blue, the mixing of these pigments results from a production error. The results also indicate the presence of Au in the sculpture, which indicates the originality of the piece. The results from this study helped restorers to choose the appropriate procedures for intervening in the sculpture and contributed to the knowledge about the manufacturing process of Brazilian baroque sculptures.

In the present paper we have conducted studies on seismological properties using worldwide data of deep earthquakes (depth larger than 70 km), considering events with magnitude greater than or equal to 4.5. This work is an extension of a previous study using a similar approach, for shallow events. We have addressed the problem under the perspective of complex networks, using a time window model to build the networks for deep earthquakes. These networks present scale-free and small-world features, contributing to strengthen the use of the time window model to construct epicenters networks. The results for deep events were analyzed using Nonextensive Statistical Mechanics and they corroborate with those found for the shallow ones, since the connectivity distribution for deep earthquakes also follows a q -exponential distribution and the scaling behavior is present. Our findings reinforce the idea of long-range correlations between earthquakes and the criticality of the seismological system.

This work presents a study of the influence of the field size of an epithermal neutron beam on the dose distribution in treatments with boron neutron capture therapy using an anthropomorphic voxel-based simulator. To calculate the doses in the tissues and organs of the head, the Monte Carlo N-Particle radiation transport code is used. The results suggest the possibility of using a beam of 6 cm in diameter for the treatment of tumours in the frontal lobe and parietal regions. With a beam of 10 cm in diameter, we could treat tumours located in the frontal lobe, parietal lobe and thalamus. The work also shows that the contribution of the secondary components (gamma rays, fast and thermal neutrons) in the calculation of the total dose can result in up to 15% of the dose in the tumour tissue, 68% of the dose in the healthy brain tissue and 87% of the dose in the non-cephalic regions.

The understanding of long-distance relations between seismic activities has for long been of interest to seismologists and geologists. In this paper we have used data from the worldwide earthquake catalog for the period between 1972 and 2011 to generate a network of sites around the world for earthquakes with magnitude m ≥ 4.5 in the Richter scale. After the network construction, we have analyzed the results under two viewpoints. First, in contrast to previous works, which have considered just small areas, we showed that the best fitting for networks of seismic events is not a pure power law, but a power law with exponential cutoff; we also have found that the global network presents small-world properties. Second, we have found that the time intervals between successive earthquakes have a cumulative probability distribution well fitted by nontraditional functional forms. The implications of our results are significant because they seem to indicate that seisms around the world are not independent. In this paper we provide evidence to support this argument.

In this work we study the influence of considering partial sets of earthquakes data has on the temporal and spatial probability distributions of earthquakes, using data from the California region between 2003 and 2016, with different thresholds for magnitude and depth of hypocenters. For this we have considered sequences of earthquakes where we have “jump”, or pulled, a given fixed number of actually sequential earthquakes. Through the concepts of Non-Extensive Statistical Mechanics for the time interval between earthquakes, we have found that the increase of the jump between earthquakes forming the sequence, affects the non-extensive characteristic of the system in the temporal probability distribution, denoted by a change in the value of the entropic index q , for relatively small jump sizes. However, for the distance between earthquakes, we observe that the increase of jumps lets untouched the non-extensive characteristic of the system, keeping the entropic index values q approximately constant. This analysis allows not just to show the robustness of the Non-Extensive Statistical Mechanics treatments for the study of earthquakes, but also their limits of applicability with respect to jumps or data loss. At the same time, it is a very useful test for memory effects and long-range interactions.

In this work, microsamples extracted from a Saint John the Evangelist polychrome sculpture, dating from the beginning of the eighteenth century and found in Rio de Janeiro, Brazil, were analyzed with micro-XRF and complimentary X-ray Fluorescence (XRF) techniques, Raman Spectroscopy, and Optic Microscopy (OM). As a result of the study, the pigments azurite [2CuCO3·Cu(OH)2], massicot [PbO], vermilion [HgS], calcite [CaCO3] and gypsum [CaSO4.2H2O] were characterized. Through the images obtained by the microelemental mapping, it was verified that some tonalities were produced by pigment mixing, i.e., the green polychrome on the sculpture resulted from a mix of azurite and massicot. In addition to the characterization of the materials used in the sculpture, numerical iterations were implemented using Python programming language to perform correlations between the elemental maps, the values of which were validated by the results of the study.

In this paper we focus on the statistical distribution of time intervals between geomagnetic reversals. Recently the Tsallis distribution was pointed out as a possible alternative to previous proposals. We have performed statistical tests to further prove this and find the parameters of the Tsallis distribution that better fit the data. Additionally we have analyzed the correlation of time intervals between consecutive reversals to show the presence of memory effects on the mechanism that generates them, as could be expected for some Tsallis systems.

In this article we implemented simulations of the OFC model for earthquakes for two different topologies: regular and small-world, where in the latter the links are randomly rewired with probability p. In both topologies, we have studied the distribution of time intervals between consecutive earthquakes and the border effects present in each one. In addition, we also have characterized the influence that the probability p produces in certain characteristics of the lattice and in the intensity of border effects. From the two topologies, networks of consecutive epicenters were constructed, that allowed us to analyze the distribution of connectivities of each one. In our results distributions arise belonging to a family of non-traditional distributions functions, which agrees with previous studies using data from actual earthquakes. Our results reinforce the idea that the Earth is in a critical self-organized state and furthermore point towards temporal and spatial correlations between earthquakes in different places.

The understanding of long-distance relations between seismic activities has for long been of interest to seismologists and geologists. In this paper we have used data from the world-wide earthquake catalog for the period between 1972 and 2011, to generate a network of sites around the world for earthquakes with magnitude m ≥ 4.5 on the Richter scale. After the network construction, we have analyzed the results under two viewpoints. Firstly, in contrast to previous works, which have considered just small areas, we showed that the best fitting for networks of seismic events is not a pure power law, but a power law with an exponential cutoff. We also have found that the global network presents small-world properties. The implications of our results are discussed.

This paper presents an analysis of the distribution of periods between consecutive reversals of the Earth’s magnetic field through a non-parametric statistics. The study analyzes whether data in different periods of reversal belong to the same distribution, the distribution type and whether the polarity states are equivalent. This analysis was performed for periods from 0 to 40 Ma, 40 to 80 Ma and 120 to 160 Ma. It was found that the data from the three periods show identical statistical characteristics which leads to the symmetry between the states of polarity and to a distribution compatible with a power law, which shows the possibility of a critical phenomenon acting on the geodynamo. The fact that the data obey a power law distribution prompted a comparison with synthetic data generated using two models based on criticality of reversals (one of them self-organized). These simple models reproduce some features of reversals as its temporal evolution and distribution of polarity intervals, and show a similarity with paleomagnetic data.Keywords: geomagnetic reversals, power law, self-organized criticality. RESUMO. Este artigo apresenta uma análise da distribuição de períodos entre reversões consecutivas do campo magnético da Terra através de uma estatística não-paramétrica. O estudo analisa se os dados dos diferentes períodos de reversão pertencem a uma mesma distribuição, o tipo de distribuição que eles obedecem e se os estados de polaridade são equivalentes. Esta análise foi realizada nos períodos de 0 a 40 Ma, de 40 a 80 Ma e de 120 a 160 Ma. Encontrou-se que os dados dos três períodos apresentam características estatísticas idênticas, o que leva à simetria entre os estados de polaridade e a uma distribuição compatível com uma lei de potência, o que mostra a possibilidade de um fenômeno crítico atuando no geodínamo. O fato dos dados obedecerem a uma distribuição de lei de potências motivou uma comparação com dados sintéticos gerados através de dois modelos de reversões baseados em criticalidade (um deles auto-organizado). Estes modelos simples reproduzem algumas características das reversões, como sua evolução temporal e a distribuição de intervalo de polaridade, e mostram uma similaridade com dados paleomagnéticos.Palavras-chave: reversões geomagnéticas, lei de potências, criticalidade auto-organizada.