Uncertainty quantification through the Monte Carlo method in a cloud computing setting

The Monte Carlo (MC) method is the most common technique used for uncertainty quantification, due to its simplicity and good statistical results. However, its computational cost is extremely high, and, in many cases, prohibitive. Fortunately, the MC algorithm is easily parallelizable, which allows its use in simulations where the computation of a single realization is very costly. This work presents a methodology for the parallelization of the MC method, in the context of cloud computing. This strategy is based on the MapReduce paradigm, and allows an efficient distribution of tasks in the cloud. This methodology is illustrated on a problem of structural dynamics that is subject to uncertainties. The results show that the technique is capable of producing good results concerning statistical moments of low order. It is shown that even a simple problem may require many realizations for convergence of histograms, which makes the cloud computing strategy very attractive (due to its high scalability capacity and low-cost). Additionally, the results regarding the time of processing and storage space usage allow one to qualify this new methodology as a solution for simulations that require a number of MC realizations beyond the standard.     

Residual N and P fertilizer effect and fertilizer recovery on intercropped and sole-cropped corn and bean in semiarid northeast Brazil

The effects of a single ¹⁵N and P fertilizer application (16 and 12 kg ha^–1) on intercropped and sole-cropped corn and beans was followed over three consecutive years. Grain (0.1–0.9 ton ha^–1 yr^–1) and straw productions (0.2–2.5 ton ha^–1 yr^–1) were limited by rainfall and showed small responses to fertilizer. In the first year, plant N uptake was more than twice the fertilizer amounts, while P uptake was less than half the fertilizer amounts. Plant N derived from fertilizer was low (9–19%). Sole corn took up more (34%) than beans (16%) and the combined intercrop (26%) and also had higher recovery of fertilizer in the soil than single beans (50% against 28%). The distribution of fertilizer N and P in the soil showed a similar pattern in all treatments, with a high concentration around the application spot and decreasing concentrations at greater distances and above and below this point. Total P increases in a soil volume 10 cm around the application spot corresponded to 60% of the amount applied. Fertilizer contributions to the second crop were < 3% of total plant N and represented <6% of the applied amount. Therefore, the residual fertilizer effect on production was attributable to P. The patterns of fertilizer N and P distribution in the soil remained similar but N recoveries decreased 14–18%. Despite low rainfall, low productivities and reasonable proportions of fertilizer N remaining in the soil, the residual effects of the applied fertilizer N were too low to justify a fertilizer recommendation based on economic returns on the investment.     

An integrated semantics for reasoning about SysML design models using refinement

SysML is a variant of UML for systems design. Several formalisations of SysML (and UML) are available. Our work is distinctive in two ways: a semantics for refinement and for a representative collection of elements from the UML4SysML profile (blocks, state machines, activities, and interactions) used in combination. We provide a means to analyse and refine design models specified using SysML. This facilitates the discovery of problems earlier in the system development lifecycle, reducing time, and costs of production. Here, we describe our semantics, which is defined using a state-rich process algebra and implemented in a tool for automatic generation of formal models. We also show how the semantics can be used for refinement-based analysis and development. Our case study is a leadership-election protocol, a critical component of an industrial application. Our major contribution is a framework for reasoning using refinement about systems specified by collections of SysML diagrams.     

In vitro evaluation of natural hydroxyapatite from Osteoglossum bicirrhosum fish scales for biomedical application

This study reports the obtainment of bioactive hydroxyapatite (HAp) extracted from scales of arowana fish (FSHA) (Osteoglossum bicirrhosum) by alkaline treatment followed by calcination at 600 and 800°C. The cell viability and bioactivity of hydroxyapatite particles (FSHA) were investigated and compared with those of HAp synthesized (s.HA) by the precipitation method. The HAp particles from fish scales showed non-toxic behavior to dental pulp stem cells similar to HAp synthesized. Additionally, bioactivity assays show that the Hap from natural source forms the bone-like apatite layer faster than s.HA sample, after being incubated in McCoy medium for 3 days. The results illustrate that HAp obtained from Osteoglossum bicirrhosum fish scale bio-waste showed excellent biocompatibility. Besides, this study provides an effective method for converting low-cost bio-waste into a value-added and it can be a potential alternative biomaterial for various biomedical applications.     

Probabilistic modeling of a nonlinear dynamical system used for producing voice

This paper is devoted to the construction of a stochastic nonlinear dynamical system for signal generation such as the production of voiced sounds. The dynamical system is highly nonlinear, and the output signal generated is very sensitive to a few parameters of the system. In the context of the production of voiced sounds the measurements have a significant variability. We then propose a statistical treatment of the experiments and we developed a probability model of the sensitive parameters in order that the stochastic dynamical system has the capability to predict the experiments in the probability distribution sense. The computational nonlinear dynamical system is presented, the Maximum Entropy Principle is used to construct the probability model and an experimental validation is shown.     

Technological characterization of kaolin: Study of the case of the Borborema–Seridó region (Brazil)

The technological characterization of kaolin from the Borborema–Seridó region has shown that it is predominantly kaolinitic, pseudoplastic and thixotropic; approximately 50% of its particles size is less than 2 μm. By using electronic paramagnetic resonance (EPR) and Mössbauer spectroscopy (ME), it was observed that Fe²⁺ and Fe³⁺ substitute Al³⁺ in octahedral sites of kaolinite. After magnetic separation followed by chemical bleaching, kaolin reached a brightness index of 87.72% ISO and an opacity index of 85.58% ISO, indicating that it can be used mainly as a filler and a coating in the paper industry, paint and pottery, among other industries.     

Micronised-roasted coffee from unripe fruits improves bioactive compounds and fibre contents in rice extruded breakfast cereals

Unripe green coffee is one of the by-products from coffee processing that does not have many applications in higher value-added food products. This study aimed to evaluate the chemical, technological, and sensory properties of rice-based breakfast cereal made with micronised-roasted coffee (MRC) from green coffee fruits. The products were elaborated with different MRC concentrations (2, 5 and 9%) and manufactured in a single screw extruder. Data were analysed by analysis of variance and Tukey's test (p < 0.05). The increase in MRC concentration improved the contents of caffeine, chlorogenic and caffeic acids in the breakfast cereals, and reduced the luminosity and expansion index due to the presence of brown colour and fibres from coffee beans. The cereal made with 5% of MRC was more accepted by consumers. Thus, MRC has proven to be a potential source of bioactive compounds, fibres and natural brownish colour for breakfast cereals.     

Prospecting technologies for photovoltaic solar energy: Overview of its technical-commercial viability

There are many technologies that may emerge and eventually disappear over the years. This fact makes the monitoring of technological trends as well as the anticipation of the direction of technological change paramount. This article aims to carry out the prospection of technologies, focusing on its technical-commercial viability, for solar photovoltaic energy. The research method had a qualititative-quantitative approach with application of the Delphi technique. In the conduction of the Delphi technique, seven steps were followed, ranging from the selection of the specialists to the considerations of their opinions regarding the future of nine photovoltaic technologies. The results of the research indicate that in 2020, the cells monocrystalline, multicrystalline, and amorphous silicon; cadmium telluride; indium/copper selenide, indium, and gallium diselenide; and multicompound III-V cells will have technical and commercial viability and that dye-sensitized silicon nanowire and carbon nanostructure-based cells will not be viable. For the year 2025, monocrystalline and multicrystalline silicon cells and those of multicompounds III-V will still be technically and commercially viable. Silicon nanowire; amorphous silicon; cadmium telluride; indium/copper, selenium, and gallium diselenide dye-sensitized cells; and organic photovoltaic cells, including those based on carbon nanostructure, may be viable. This study is important, because the technological prospecting of the photovoltaic cells determines the possible trajectories of these cells, in a way that helps the companies of the sector to anticipate the strategic scenarios, thus facilitating the decision making process.     

Structure–properties relationship in single polymer composites based on polyamide 6 prepared by in-mold anionic polymerization

Single polymer composites (SPCs) based on polyamide 6 (PA6) were prepared by in-mold activated anionic ring-opening polymerization (AAROP) of caprolactam in the presence of PA6 textile fibers. The influence of the reinforcing fibers content, their surface treatment, as well as of the temperature of AAROP upon the morphology, crystalline structure, and mechanical properties of the resulting SPCs was followed. The presence of oriented transcrystalline layer (TCL) on the surface of the reinforcing fibers was demonstrated by means of microscopy methods. Its orientation and polymorph structure were determined by synchrotron wide-angle X-ray scattering. Studies on the mechanical behavior in tension of the SPCs showed a well-expressed growth of the stress at break (70–80 %) and deformation at break (up to 150–190 %) in composites with 15–20 wt% of reinforcements. The best mechanical properties were found in SPCs whose reinforcing fibers were solvent-pretreated prior to AAROP in order to remove the original finish. In these samples a stronger adhesion at the fiber/matrix interface was proved by scanning electron microscopy of cryofractured samples. This effect was related to a thinner TCL in which the α-to-γ polymorph transition is impeded.