Experience with model-based performance, reliability, and adaptability assessment of a complex industrial architecture

In this paper, we report on our experience with the application of validated models to assess performance, reliability, and adaptability of a complex mission critical system that is being developed to dynamically monitor and control the position of an oil-drilling platform. We present real-time modeling results that show that all tasks are schedulable. We performed stochastic analysis of the distribution of task execution time as a function of the number of system interfaces. We report on the variability of task execution times for the expected system configurations. In addition, we have executed a system library for an important task inside the performance model simulator. We report on the measured algorithm convergence as a function of the number of vessel thrusters. We have also studied the system architecture adaptability by comparing the documented system architecture and the implemented source code. We report on the adaptability findings and the recommendations we were able to provide to the system’s architect. Finally, we have developed models of hardware and software reliability. We report on hardware and software reliability results based on the evaluation of the system architecture.     

Overview of the scientific production in the Pharmacy area in Brazil: profile and productivity of researchers granted with fellowships by the National Council for Scientific and Technological Development

In Brazil, the National Council for Scientific and Technological Development (CNPq) distributes productivity fellowships in research (RS) as a recognition to individuals with outstanding productivity levels in their areas. The aim of this study is to evaluate the scientific production of the Brazilian Pharmacy area, one division of the Health Sciences Great Area of CNPq, considering the profile and productivity levels of RS fellows. The results showed that most of the 156 active RS fellows in 2015 were female, with doctorate completed in the Southeast region (mainly in University of São Paulo) and with research activities developed in the South and Southeast regions. Most of their work was published in journals classified as B1 and B2 Qualis in Pharmacy by the Coordination for the Improvement of Higher Education Personnel (CAPES), with high prevalence of publications in local journals and/or specialized on medicinal plants. Besides, they featured much dependence on advising and productivity indexes related to the category and level of RS fellowship. The evolution of such data must be continually evaluated to determine the influence of CNPq productivity fellowships on performance and stratification of researchers in the Pharmacy area in Brazil.     

Sugarcane bagasse cellulose/HDPE composites obtained by extrusion

Natural fibers used in this study were both pre-treated and modified residues from sugarcane bagasse. Polymer of high density polyethylene (HDPE) was employed as matrix in to composites, which were produced by mixing high density polyethylene with cellulose (10%) and Cell/ZrO₂·nH₂O (10%), using an extruder and hydraulic press. Tensile tests showed that the Cell/ZrO₂·nH₂O (10%)/HDPE composites present better tensile strength than cellulose (10%)/HDPE composites. Cellulose agglomerations were responsible for poor adhesion between fiber and matrix in cellulose (10%)/HDPE composites. HDPE/natural fibers composites showed also lower tensile strength in comparison to the polymer. The increase in Young’s modulus is associated to fibers reinforcement. SEM analysis showed that the cellulose fibers insertion in the matrix caused an increase of defects, which were reduced when modified cellulose fibers were used.     

Sintering of porous alumina obtained by biotemplate fibers for low thermal conductivity applications

In this research report, a sintering process of porous ceramic materials based on Al₂O₃ was employed using a method where a cation precursor solution is embedded in an organic fibrous cotton matrix. For porous green bodies, the precursor solution and cotton were annealed at temperatures in the range of 100–1600 °C using scanning electron microscopy (SEM) and thermogravimetric (TG) analysis to obtain a porous body formation and disposal process containing organic fibers and precursor solution. In a structure consisting of open pores and interconnected nanometric grains, despite the low porosity of around 40% (calculated geometrically), nitrogen physisorption determined a specific surface area of 14 m²/g, which shows much sintering of porous bodies. Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analytical methods revealed a predominant amount of α-Al₂O₃ in the sintered samples. Thermal properties of the sintered Al₂O₃ fibers were obtained by using the Laser Flash which resulted in the lower thermal conductivity obtained by α-Al₂O₃ and therefore improved its potential use as an insulating material.     

Multi-objective Adaptive Evolutionary Algorithm to Enhance Voltage Stability in Power Systems

International Journal of Control, Automation and Systems - Problems with two or more conflicting objectives have been handled as needing a multi-objective approach in recent years. The solution for...     

Surface and grain‐boundary excess of ZnO‐doped SnO2 nanopowders by the selective lixiviation method

The primary characteristic of nanopowders is the high surface area and consequently high fraction of atoms on the interfaces, which changes the energy of the system. The additive distribution in the nanopowder interfaces is a fundamental aspect to control the energy, particle size, and final properties of nanopowders. In this work, the surface excess was determined using a selective lixiviation method, where a low‐water‐soluble oxide, SnO₂, was used as the matrix, and a high‐water‐soluble oxide, ZnO, was used as the additive. The X‐ray photoelectron spectroscopy (XPS) analysis confirmed that ZnO segregated on SnO₂ surfaces. However, after acid lixiviation the same analysis showed an undetectable surface concentration of ZnO. The evaluation of the nanostructure change and surface composition enables us to calculate the heat of segregation for the grain boundary and surface and the interface energy reduction because of segregation. At low‐ZnO concentrations, the additive solubilizes in the bulk and promotes particle growth. However, the segregation to the grain boundary and surface determines the relative stability of each interface, which promotes hard agglomeration and particle size stabilization at intermediated ZnO amounts. At high‐ZnO concentrations, the surface segregation stabilizes the solid‐gas interface and decreases the agglomeration and final particle size.     

Solid-state NMR for the analysis of interface excesses in Li-doped MgAl2O4 nanocrystals

Interface segregation plays a governing role in nanocrystalline ceramics properties due to the relative increase in the interfacial volume fraction. However, due to the complexity of the detection and quantification of interfacial excesses at the nanoscale, the role of ionic dopants or additives on microstructural evolution and thermodynamics can be easily underestimated. In this work, we address the spatial distribution of Li⁺ as a dopant in magnesium aluminate spinel nanoparticles. This is achieved through a novel method for the detection and quantification of Li⁺ across the surface, grain boundary, and bulk (crystal lattice). Based on selective lixiviation combined with chemical analysis, we were able to quantify the amount of Li⁺ forming surface excess, whereas the quantitative solid-state nuclear magnetic resonance technique enabled the quantification of Li⁺ segregated in the grain boundaries and dissolved in the lattice. This comprehensive understanding of the Li⁺ distribution across the nanoparticles makes possible an unprecedented interpretation of coarsening and sintering, with a clear correlation between the microstructure and the Li⁺ distribution. Although the work focuses on MgAl₂O₄, the proposed combination of techniques is expected to have a positive impact on the understanding of other multicomponent nanoscale systems.     

Development of biodegradable PLA/PBT nanoblends

Poly(lactic acid)/poly(butylene terephthalate) (PLA/PBT) blends with 3, 5, and 10 wt % of PBT were produced in a twin‐screw extruder, with the addition of ethylene–glycidyl methacrylate copolymer as compatibilizer. An uncompatibilized PLA/PBT blend with 5 wt % of PBT was prepared for comparison studies. The epoxy reactive groups in the compatibilizer allowed modification of the interfacial tension in the blends and reduced the PBT dimensions. The crystallinity of the blends was studied, and its influence on mechanical properties was analyzed. Tensile tests showed an increase in strain at break from 3% for neat PLA to 49% for PLA with 3 wt % PBT, while the tensile modulus dropped from 3.59 GPa to 3.35 GPa for the same samples. Izod results showed a transition from a brittle behavior of PLA to a ductile one for compatibilized blends. These results indicate that the nanometer‐size dispersed phase was effective in changing the deformation behavior of the matrix without a significant loss of modulus. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45951.     

Interface excess on Sb-doped TiO2 photocatalysts and its influence on photocatalytic activity

Titanium dioxide (TiO₂) is a well-known photocatalyst that has been used in photocatalysis and has been studied as an alternative for artificial photosynthesis cells. Many works have tried doping this material with different elements to increase its photoactivity; however, a consequence of doping that has not received much attention is the segregation at the nanoparticle interfaces, such as the surface and the grain boundary (GB). In this study, Sb-doped TiO₂ nanoparticles have been produced by the polymeric precursor method, with the compositional range varying from 0 to 2 mol% Sb. The surface excess was measured by the surface lixiviation method, and the GB excess was calculated considering the total amount of Sb and its solubility in the TiO₂ bulk. The results showed that Sb interfacial segregation at both surface and GB increased the specific surface areas, reduced the crystallite sizes, increased the presence of the rutile phase, and changed the CO₂ adsorption, evidenced by DRIFT spectroscopy. The photoactivity was tested by the degradation of acetaminophen (ACT) under UV irradiation, revealing an increase of ~53% of activity for 0.05 mol% Sb-doped TiO₂ compared to undoped TiO₂.     

Dynamics of the yeast flora in artisanal country style and industrial dry cured sausage (yeast in fermented sausage)

Yeast can act as an adjunct in the sausage-making process as a way to prevent or reduce excessive acidification during aging of products. Two kinds of process were studied: industrial and artisanal country style. Three hundred and fifty three yeast strains were isolated, characterized and identified by biochemical and molecular techniques. Evolution of pH, Aw, weight loss, bacterial growth and proteolytic and lipolytic activity was studied. Final pH in artisanal country style product was higher than in the industrial sausage. There was little difference noted between final weights of products but it was observed a lower yeast count in artisanal country style sausage. No relevant difference was observed in center or surface yeast count in both products. The biochemical assay identified six yeast genera and the molecular test confirmed four different genera, and further analysis showed predominance of the genera Debaryomyces. The relations between this four genera and isolation point (center or surface of sausage) were established. The presence of yeast in the center/surface of ART sausage was more prevalent than in the same places of industrial sausage.