Manufacturing and testing of 3D-printed polymer isogrid lattice cylindrical shell structures

This article focuses on the use of fused deposition modeling (FDM) technology to manufacture and test polymer isogrid lattice cylindrical shell (LCS) structures with equilateral triangular unit-cells using non-professional and conventional 3D printing software and hardware. A parametric and automated 3D model for these structures is created in SolidWorks using the Visual Basic (VBA) programming language. Different configurations of the isogrid LCS structure are modeled, manufactured, and tested in order to determine the compressive structural strength and stiffness, as well as to investigate structural instability. The experimental results are used to deduce the inherent limitations of 3D printing, including the inhomogeneities, imperfections, and non-isotropic nature of FDM, as well as the effect of the configurations on local buckling behavior. The results suggest that coupling between local and global buckling has an impact on the compressive stiffness and strength of LCS structures, reducing the accuracy of structural designs neglecting these effects.F71E-503E-DE74 | AD?LIO MANUEL DE SOUSA CAVADASN/

Manuseio de min?rio de ferro coesivo sob umidade natural.

Programa de P?s-Gradua??o em Engenharia Mineral. Departamento de Engenharia de Minas, Escola de Minas, Universidade Federal de Ouro Preto.O tratamento de min?rios a umidade natural tem se tornado cada vez mais relevante, ora por restri??es a opera??es a ?mido que resultem em disposi??o de rejeitos em barragens, ora por abrir a possibilidade de pronta mistura de min?rios diversos. A maior dificuldade nessas opera??es ? o manuseio dos materiais intemperizados (em especial os goeth?ticos e com argilominerais), ou com maior umidade, os quais tendem a ser coesivos, exigindo cuidados adicionais no seu manuseio, principal desafio para o tratamento a umidade natural. A correta configura??o de chutes de transfer?ncia, tremonhas e silos, nem sempre, ? suficiente para evitar interrup??es de fluxo no circuito de beneficiamento e carregamento. Al?m do impacto no sistema produtivo (os quais podem se estender por v?rias horas), sobretudo no per?odo chuvoso, a exposi??o ao risco dos operadores nas atividades de desobstru??o ? bastante elevada. Para esta pesquisa, foi utilizada uma amostra de min?rio de ferro proveniente da Mina do Pico. A escoabilidade foi investigada sob diferentes condi??es, empregando calha retangular de inclina??o controlada, em escala de bancada. Os seguintes materiais de revestimento foram estudados: a?o-carbono ASTM A-36 com revestimento soldado (CDP), polietileno de ultra-alta massa molecular (UHMW), hardox, borracha natural, arcoplate e poliuretano. O UHMW resultou na melhor efici?ncia de escoamento e menor ?ngulo de atrito com a parede. Nas condi??es testadas, o aditivo reol?gico Slipcoat MRA? Max n?o aumentou significativamente a efici?ncia de escoamento. J? a vibra??o como agente auxiliar de descarga mec?nica, melhorou consideravelmente a efici?ncia de escoamento.The treatment of mineral ores with natural moisture has become increasingly relevant, sometimes due to restrictions on wet operations that result in disposal of tailings in dams, and sometimes because it opens the possibility of ready mixing of various ores. The biggest difficulty in these operations is the handling of weathered materials (especially goethitic and with clay minerals), or with higher humidity, which tend to be cohesive, requiring additional care in their handling, the main challenge for the treatment of natural moisture. The correct configuration of transfer chutes, hoppers and silos is not always sufficient to avoid interruptions in flow in the processing and loading circuit. In addition to the impact on the production system (which can last for several hours), especially in the rainy season, the risk exposure of operators in clearing activities is quite high. For this research, a sample of iron ore from Mina do Pico was used. The flowability was investigated under different conditions, using a rectangular chute with controlled inclination, on a bench scale. The following coating materials were studied: ASTM A-36 carbon steel with welded coating (CDP), ultra high molecular weight polyethylene (UHMW), hardox, natural rubber, arcoplate and polyurethane. The UHMW resulted in the best flow efficiency and the lowest friction angle with the wall. Under the conditions tested, the rheological additive Slipcoat MRA ? Max did not significantly increase the flow efficiency. Vibration as an auxiliary agent for mechanical discharge, considerably improved the flow efficiency

Silagens de capim-elefante aditivadas com coprodutos do biodiesel

O presente trabalho foi realizado com apoio da Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior ? Brasil (CAPES) ? C?digo de Financiamento 001.Objetivou-se avaliar os efeitos da torta de maca?ba e farelo de crambe, oriundos da cadeia produtiva do biodiesel, em diferentes n?veis de inclus?o na ensilagem de capim-elefante. O delineamento experimental foi o inteiramente casualizado, com quatro repeti??es. O material foi ensilado em silos experimentais elaborados com tubos de PVC com tampas providas de v?lvula tipo Bunsen, compactou-se o material obtendo-se massa espec?fica de 600 kg/m3. Foi analisado teores de ?cidos org?nicos, popula??o microbiana, composi??o qu?mico-bromatol?gica e as perdas geradas durante o processo fermentativo. Os tratamentos foram dispostos em esquema fatorial 3 x 6, sendo tr?s n?veis de inclus?o de cada coproduto do biodiesel (0; 10 e 20%) e seis tempos de abertura dos silos (1; 5; 10; 20; 40 e 60 dias ap?s a ensilagem). A torta de maca?ba foi eficiente como aditivo absorvente de umidade nas silagens de capim-elefante, no qual proporcionou eleva??o dos teores de mat?ria seca, al?m da melhoria no processo fermentativo, que favoreceu o desenvolvimento de microrganismos desej?veis, e, reduziu a popula??o de fungos provavelmente por meio da a??o antif?ngica propiciada pela adequada produ??o de ?cido ac?tico, o que favoreceu baixa produ??o de etanol. Houve redu??o dos teores de ?cido but?rico, aumento de ?cido l?tico, e, consequente redu??o dos valores de pH, que foram satisfat?rios para a conserva??o do material ensilado. N?veis crescentes da torta de maca?ba reduziram a prote?lise no material ensilado, o que resultou em menores concentra??es de nitrog?nio amoniacal. Os teores de fibras foram reduzidos com a adi??o da torta de maca?ba, os teores de prote?na elevaram-se, por?m, n?o foram t?o expressivos, n?o houve contribui??o da torta de maca?ba sobre os carboidratos sol?veis. Os teores de extrato et?reo aumentaram com os n?veis crescentes da torta de maca?ba, o que deve-se atentar para que o uso na alimenta??o animal n?o limite o consumo de mat?ria seca e reduza a digestibilidade da fibra. Nas silagens de capim-elefante com 20% da torta de maca?ba, devem ser misturados a outros alimentos com concentra??o de extrato et?reo menor, as perdas por gases e efluentes foram reduzidas e a recupera??o de mat?ria seca nas silagens de capim-elefante foi aumentada com a inclus?o da torta de maca?ba, sendo que a adi??o de 20% proporcionou melhores resultados. O farelo de crambe adicionado na ensilagem de capim-elefante foi eficiente na melhoria do processo fermentativo atrav?s da eleva??o dos teores de mat?ria seca, da contribui??o para o desenvolvimento de microrganismos ben?ficos em detrimento dos indesej?veis, da predomin?ncia da fermenta??o l?tica com consequente redu??o do pH, al?m do incremento do valor nutricional, principalmente pela eleva??o do teor proteico e redu??o dos teores de fibras, contudo, o farelo de crambe favoreceu a eleva??o dos teores de nitrog?nio amoniacal. As perdas por gases e efluentes foram reduzidas e a recupera??o de mat?ria seca nas silagens de capim-elefante foi aumentada com a inclus?o do farelo de crambe. O maior n?vel de inclus?o (20%) do farelo de crambe promoveu as melhores caracter?sticas nas silagens de capim-elefante.Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Tese (Doutorado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2018.The objective of this study was to evaluate the effects of maca?ba cake and crambe bran from the biodiesel production chain on different levels of inclusion in elephant grass silage. The experimental design was completely randomized, with four replications. The material was ensiled in experimental silos made with PVC tubes with caps equipped with a Bunsen type valve, the material was compacted to obtain a specific mass of 600 kg/m3. The content of organic acids, microbial population, chemical-bromatological composition and the losses generated during the fermentation process were analyzed. The treatments were arranged in a 3 x 6 factorial scheme, with three inclusion levels of each biodiesel co-product (0, 10 and 20%) and six silos opening times (1, 5, 10, 20, 40 and 60 days after the silage). The maca?ba cake was efficient as a moisture-absorbing additive in elephant grass silages, in which it increased the dry matter contents, as well as improving the fermentation process, which favored the development of desirable microorganisms, and reduced the fungus population probably through the antifungal action provided by the adequate production of acetic acid, which favored low ethanol production. There was a decrease in butyric acid, increase of lactic acid, and consequent reduction of pH values, which were satisfactory for the conservation of silage. Increasing levels of maca?ba cake reduced the proteolysis in the ensiled material, which resulted in lower concentrations of ammonia nitrogen. The fiber contents were reduced with the addition of the maca?ba cake, the protein levels were elevated, however, they were not as expressive, there was no contribution of the maca?ba cake to the soluble carbohydrates. Ethereal extract contents increased with the increasing levels of maca?ba cake, which should be taken care that the use in animal feed does not limit dry matter consumption and reduce fiber digestibility. In the elephant grass silages with 20% of the maca?ba cake, they should be mixed with to other foods with a lower concentration of ethereal extract, gas and effluent losses were reduced and dry matter recovery in elephant grass silages was increased with the inclusion of maca?ba cake, and the addition of 20% provided better results. The crambe bran added in elephant grass silage was efficient in improving the fermentation process by raising dry matter contents, contributing to the development of beneficial microorganisms to the detriment of undesirable ones, the predominance of lactic fermentation with consequent reduction of pH , in addition to the increase in nutritional value, mainly due to the elevation of protein content and reduction of fiber content, however, the crambe bran favored the elevation of ammoniacal nitrogen contents. Gaseous and effluent losses were reduced and recovery of dry matter in elephant grass silages was increased with the inclusion of crambe bran. The highest level of inclusion (20%) of crambe bran promoted the best characteristics in elephant grass silages

New insight into zinc oxide doped with iron and its exploitation to pollutants abatement

This study aims to investigate how the photocatalytic efficiency of zinc oxide can be improved by introducing doping species into its crystal lattice. New materials based on zinc oxide doped with iron, have been synthesized using different methods, characterized and tested toward the abatement of selected organic molecules. The different synthetic strategies followed comprised sol-gel, precipitation and hydrothermal processes, in order to identify which one is capable of guaranteeing the best photocatalytic performances.The photoactivity of the new semiconductors was firstly tested using phenol as a model molecule subjected to irradiation under UV-A light. Phenol abatement is particularly favoured when using ZnO prepared via hydrothermal method and doped with iron at 0.5%. These materials were then tested toward the elimination of ketoprofen, an emerging pollutant substance, from water and real wastewater. Ketoprofen and its transformation products are completely abated within 30 min in pure water or in 1 h in wastewater

Lattice microstructure design for cathode electrodes for high-performance lithium-ion batteries

The electrode geometry is an essential parameter affecting the cycling performance of batteries. In this work, the effect of lattice geometry of the cathode electrode on battery performance was studied by theoretical simulations keeping its volume constant. It was observed that the variation of the lattice geometry improves the cycling performance when compared to conventional planar geometry. The improvement of the cycling performance in the lattice geometry is related to variations in the electrolyte current density. It was demonstrated that the lattice geometry allows to improve the discharge performance in lithium-ion batteries at higher discharge rates.511F-603F-4B30 | Francisco MirandaN/

Density Perturbations in the Brans-Dicke Theory

We analyse the fate of density perturbation in the Brans-Dicke Theory, giving a general classification of the solutions of the perturbed equations when the scale factor of the background evolves as a power law. We study with details the cases of vacuum, inflation, radiation and incoherent matter. We find, for the a negative Brans-Dicke parameter, a significant amplification of perturbations.Comment: 26 pages, latex fil

Relationship between power condition, agility, and speed performance among young roller hockey elite players

Purpose. The study was intended to describe the correlations between speed performance (11 m, 22 m, and 33 m) and agility test in skates with determinants of muscular power (squat jump, countermovement jump) in young Portuguese roller hockey athletes involved in a regional selection. Methods. A cross-sectional study was conducted among 10 male roller hockey players with mean (? SD) age of 14.20 (0.57) years, involved in the Portuguese national competition of under-15, making part of the final Oporto district selection of players to participate in inter-regional selections competition. Their mean (? SD) weight, height, body mass index, and sum of the skinfolds were 58.62 (8.78) kg, 165.72 (8.45) cm, 21.26 (1.52) kg/m2, 51.80 (14.91) mm, respectively. Furthermore, it strength was measured with squat jump and countermovement jump; sprinting time at 11 m, 22 m, and 33 m was determined, as well as time in an agility t-test, conducted in roller skating. Spearman correlation coefficients were calculated to test the associations. Results. Significant inverse correlations between vertical jumps, a practical method of power training monitoring, and linear velocity in skating (countermovement jump vs. speed, ?0.78) were found. Despite the increasing complexity of the agility test, a moderate inverse correlation with strength was observed, too (?0.48). Conclusions. Lower limbs explosive strength turned out a strong predictor of skating linear speed and agility among young roller hockey players, providing a simple evaluation tool of important determinants of performance.D915-7373-ED16 | Cesar LeaoN/

Effects of bodyweight neuromuscular training with and without instability on balance control in active universitarians

The purpose of this study was to analyse the effects of a nine-week unstable vs stable bodyweight neuromuscular training programme on balance control. Seventy-seven physically active universitarians were randomly distributed into an unstable training group (UTG), a stable training group (STG), and a control group (CG). The intervention was conducted three times a week for nine weeks. Pre- and post-intervention assessments included static balance control under an unstable surface (eyes open (EOFS), eyes closed (ECFS), challenging visual-vestibular system (CVVS)), assessed as centre-of pressure fluctuations with a force plate. A mixed ANOVA was performed to test the within- and between-subjects factors. After the intervention, no significant differences were found between groups. All groups presented significant improvements in balance measurements in EOFS (p = 0.01), ECFS (p = 0.01; p = 0.02), and CVVS (p = 0.01) conditions. The training groups tended to have significantly better balance control (antero-posterior) than the CG on EOFS. In the CVVS condition, the UTG tended to have better balance control than the CG. There was no overall significant train ing advantage gained by using unstable or stable surfaces in terms of the improvement in static balance control in active universitar ians. Both training groups exhibited similar training adaptations.D915-7373-ED16 | Cesar LeaoN/

Effect of instability and bodyweight neuromuscular training on dynamic balance control in active young adults

The aims of this study were to analyse the effects of unstable and stable bodyweight neuromuscular training on dynamic balance control and to analyse the between-group differences after the training period. Seventy-seven physically active young adults (48 males, 29 females, 19.1 ? 1.1 years, 170.2 ? 9.2 cm, 64.1 ? 10.7 kg) were distributed into an unstable training group (UTG), a stable training group (STG), and a control group (CG). Training was conducted three times a week for nine weeks. Pre-intervention and post-intervention measures included dynamic balance control using a Y Balance Test (YBT), anterior (A), posteromedial (PM), and posterolateral (PL) reach direction. A mixed ANOVA was executed to test the within-subjects factor and the between-subjects factor. Statistically significant differences were found for all YBT measures within groups (p = 0.01) and between groups (p = 0.01). After the intervention, UTG and STG presented meaningfully improved results in all YBT measures (A: 7%, p = 0.01; 4%, p = 0.02, PM: 8%, p = 0.01; 5%, p = 0.01, PL: 8%, p = 0.01; 4%, p = 0.04, respectively). No statistical changes were found for any of the measures in the CG. After the intervention, significant differences were observed between the UTG and CG for the YBTA and PM (p = 0.03; p = 0.01). The results suggest that neuromuscular training using an unstable surface had similar effects on dynamic balance control as training using a stable surface. When compared to CG, UTG showed better performance in YBTA and PM.D915-7373-ED16 | Cesar LeaoN/

The relationship between static and dynamic balance in active young adults

Purpose. The objectives were to analyse differences of static and dynamic balance between sexes and test the correlations between static and dynamic balance measures. Methods. The study involved 77 physically active adults, university students (age: 19.1 ? 1.1 years; height: 170.2 ? 9.2 cm; body mass: 64.1 ? 10.7 kg). Static balance was assessed with a force platform under Romberg conditions: a foam surface, eyes open (EOFS); eyes closed (ECFS); challenging the visual-vestibular system (CVVS). The Y Balance Test (YBT) evaluated dynamic balance in anterior, posteromedial, and posterolateral directions. One-way ANOVA examined potential differences between sexes, and the Pearson product-moment test verified the correlations between YBT and static balance measures. Results. Sex differences were found for all conditions in static balance variables: ellipse area (EA), centre of pressure displacement anteroposterior (DAP) and mediolateral (DML), mean velocity anteroposterior (VAP) and mediolateral (VML), total mean velocity (TV). Females presented a better stability index than males for EOFS (25% DAP, 20% DML, 30% VAP, 21% VML, 19% TV), ECFS (26% DAP, 32% DML, 28% VAP, 32% VML, 32% TV), and CVVS (27% EA, 26% DAP, 19% DML, 17% VAP, 20% VML, 18% TV). Males demonstrated 6% better performance on YBT posterolateral. Correlation tests revealed small to moderate correlations between static and dynamic balance, except for a large positive correlation between YBT anterior and sway area under the CVVS condition [r = 0.54 (0.19; 0.77)] for women. Conclusions. The findings indicate a weak relationship between static and dynamic balance in controlling posture.D915-7373-ED16 | Cesar LeaoN/