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Critérios para adoção de soluções de desenvolvimento multiplataforma móvel na perspectiva de desenvolvedores de software
(Universidade Federal de São Carlos, 2020-04-03) Afonso, Felipe Munhoz; Ferrari, Fabiano Cutigi; https://lattes.cnpq.br/3154345471250570; https://lattes.cnpq.br/7533101465247671
Cross-platform Development Tools are a technology that emerged to meetthe demand of development teams that operate simultaneously with more than onemobile platform. This technology mainly benefits small and medium-sized teamsthat did not have the capacity to maintain two or more different code bases for thesame project. The use of these tools has become more and more popular accord-ing to the evolution of the technology employed capable of producing applicationsincreasingly closer to one developed natively. As the popularity of cross-platformtools grows, so does the need for a concise, flexible and long-lasting way of definingtheir advantages and disadvantages over other tools. So the objective of this work isto find out through mixed methods of data gathering such as questionnaires, inter-views and practical studies what really matters to the developers, thus contributingto the evolution of the state of the art by providing a set of criteria that can beused to make comparisons. And enhancing the state of the art with a comparisonbetween the development tools most used today. Results shows that the most im-portant decision factors are Responsivity, Long Term Viability and Maintainability.It was also indentified that the most complete tools are React Native, Flutter andXamarin.
Efeitos da nitretação a plasma e do filme de carbono amorfo (a-C:H) aplicado ao aço 1020 na resistência ao desgaste em alumínio AA 3104
(Universidade Federal de São Carlos, 2020-04-03) Soares, Fábio; Rossino, Luciana Sgarbi; https://lattes.cnpq.br/0139027055418391; https://lattes.cnpq.br/2874636133937008
The AA 3104 aluminum is widely used as packaging for food storage, as it is a versatile alloy with easy mechanical conformation, however, it causes high wear to the cutting knife due to friction during the packaging operation. The objective of this study was to evaluate the wear resistance of steel containing 0.2% C, commonly applied to tools to perform forming and cutting operations on AA 3104 aluminum alloy, subjecting this steel to plasma ion nitriding and deposition treatments amorphous carbon film (a-C:H), to study the wear behavior of the material with and without surface treatment. The a-C:H films were deposited by PECVD on 1020 steel samples after cleaning the substrate by plasma ablation, with atmospheres of 80 and 90% CH4, with voltage varying between 500 and 600V. For the adhesion of a-C:H film to the metallic substrate, a silicon interface was deposited using hexamethyldisiloxane as a precursor, whose deposition was carried out with a gas flow of 30 sccm, containing 70% HMDSO and 30% argon. The plasma nitriding treatments were carried out with an atmosphere containing 80% N2 and 20% H2 with temperatures at 400, 500 and 600 °C. Also, plasma nitriding treatment was carried out where the temperature was maintained at 550 °C and the gas proportions were varied by 60% N2 and 40% H2, 80% N2 and 20% H2 and 92% N2 and 8% H2. All samples were subjected to the micro-wear test by fixed ball and the prototypes of the treated tools were tested using a wear machine specially built to simulate the friction between 1020 steel and AA 3104 aluminum. The final wear analysis was done through the optical moiré technique by phase-shifting that allowed to analyze both qualitatively and quantitatively the volume of body wear with and without treatment. Among the nitrided samples, those that were produced with higher nitrogen rates showed greater hardness due to the formation of the Fe2-3N phase, reaching values of 585 HV, however the samples with a low nitrogen atmosphere obtained Fe4N phase where they showed to be more resistant to frictional stresses due to its greater ductility in relation to the Fe2-3N phase, ensuring 60% less wear on untreated material. The a-C:H film produced with an atmosphere containing 80% CH4 showed a lower roughness among all samples (44.3 nm), leading to a lower wear volume (1.015x10-4 mm3). The a-C:H films gave steel 1020 results superior to nitriding, with a 95% reduction in wear volume. It was observed that all treated samples obtained an increase in wear resistance, when compared to the base material, thus making it possible to reduce the wear of the 1020 steel tools used for cutting aluminum AA 3104 and, subsequently, increasing its useful life.
A new class of discrete models for the analysis of zero-modified count data
(Universidade Federal de São Carlos, 2020-04-03) Silva, Wesley Bertoli da; Louzada Neto, Francisco; https://lattes.cnpq.br/0994050156415890; https://lattes.cnpq.br/7852733762870256
In this work, a new class of discrete models for the analysis of zero-modified count data has been introduced. The proposed class is composed of hurdle versions of the Poisson-Lindley, Poisson-Shanker, and Poisson-Sujatha baseline distributions, which are uniparametric Poisson mixtures that can accommodate different levels of overdispersion. Unlike the traditional formulation of zero-modified distributions, the primary assumption under hurdle models is that the positive observations are entirely represented by zero-truncated distributions. In the sense of extending the applicability of the theoretical models, it has also been developed a fixed-effects regression framework, in which the probability of zero-valued observations being generated as well as the average number of positive observations per individual could be modeled in the presence of covariates. Besides, an even more flexible structure allowing the inclusion of both fixed and random-effects in the linear predictors of the hurdle models has also been developed. In the derived mixed-effects structure, it has been considered the use of scalar random-effects to quantify the within-subjects heterogeneity arising from clustering or repeated measurements. In this work, all inferential procedures were conducted under a fully Bayesian perspective. Different prior distributions have been considered (e.g., Jeffreys' and g-prior), and the task of generating pseudo-random values from a posterior distribution without closed-form has been performed by one out of the three following algorithms (depending on the structure of each model): Rejection Sampling, Random-walk Metropolis, and Adaptive Metropolis. Intensive Monte Carlo simulation studies were performed in order to evaluate the performance of the adopted Bayesian methodologies. The usefulness of the proposed zero-modified models was illustrated by using several real datasets presenting different structures and sources of variation. Beyond parameter estimation, it has been performed sensitivity analyses to identify influent points, and, in order to evaluate the fitted models, it has been computed the Bayesian p-values, the randomized quantile residuals, among other measures. Finally, when compared with well-established distributions for the analysis of count data, the competitiveness of the proposed models has been proved in all provided examples.
Comunicação e divulgação científica de líderes de grupos de pesquisa no campo CTS: análise a partir de indicadores bibliométricos e altmétricos
(Universidade Federal de São Carlos, 2020-04-03) Galdino, Rejane; Silva, Márcia Regina da; https://lattes.cnpq.br/5381461208053330; https://lattes.cnpq.br/3638907270229514
Science has consolidated itself in the social structure as much as technology, both differing in the relationship established with society. The scientist has as a commitment to science the need for scientific communication and its social function is scientific dissemination. Taking into account the proximity between the STS field and the scientific communication and dissemination processes, this research aims to investigate the scientific publication and dissemination practices of leaders of research groups in the STS field, registered with CNPq. This is an exploratory and descriptive research that aims to verify whether researchers working in the STS Field comply with the science dissemination assumptions recommended by the Field itself. With regard to the characterization of the STS groups and the scientific production of the leaders, the area of Education has great prominence in STS studies, proposing, predominantly, to study the ways in which the STS field impacts education and the way in which Education can contribute to advances in the STS field, such as deepening and discussing ways of dealing with the issue of scientific illiteracy, which is among the themes of greatest study by leaders. Bibliometric and altmetric indicators pointed out that bibliographic production and more traditional channels, such as congresses and journals, are the most used by leaders for scientific communication. In the altmetric analysis of the articles published by the leaders, Mendeley, the academic social network, received the most attention online. Of the 87 leaders of STS research groups, 17 are authors of articles that received attention online. It is concluded that although leaders denote having a consolidated scientific communication, according to the methods used in this research, they show that there is still a way to go for effective engagement in scientific dissemination through social networks, which in a way denotes that the premises advocated by the STS Field itself of the greatest proximity between researchers and society should be encouraged.
Otimização da condutividade iônica de vitrocerâmicas condutoras por íon sódio: controle microestrutural e busca de novas composições
(Universidade Federal de São Carlos, 2020-04-03) Muñoz, Adriana Marcela Nieto; Rodrigues, Ana Candida Martins; https://lattes.cnpq.br/4499231813051400; https://lattes.cnpq.br/9018348092961208
Sodium-based materials are promising candidates for manufacturing stationary storage devices such as batteries due to their low cost and the Na high redox potential. However, the corrosion, flammability, and the degradation of cell components in sodium-ion batteries caused by the high operating temperatures may be listed as disadvantages of these devices. A possible solution to these problems is to optimize the ionic conductivity of the solid electrolyte. In this work, two methods were adopted to improve the ionic conductivity of NASICON (Na-Super Ionic Conductor) solid electrolytes. The first one focused on the substitution Si4+/P5+ in the unprecedented Na1+yTi2SiyP3-yO12 (NTSP) and Na2+yAlTiSiyP3-yO12 (NATSP) series, which allows the introduction of extra Na+ ions. In the second method, Na2AlTi(PO4)3 (NATP) and Na1.8Al0.8Ge1.2(PO4)3 (NAGP) glass-ceramics with different grain sizes were obtained to establish a correlation between microstructure and ionic conductivity. For the NTSP glass-ceramics, it was observed that the inclusion of Si4+ ions in the NASICON structure promoted an increase of up to four orders of magnitude in the total conductivity. The formation of a highly conductive phase was also seen in the compositions with a high content of silicon. In the NATSP series, there was no evidence of a Si4+/ P5+ substitution since the expansion of the unit cell was not observed. This behavior was attributed to the high tendency of precursor glasses towards phase separation. Regarding the NATP and NAGP glass-ceramics, materials with average grain size from the order of nanometers to micrometers were obtained. Therefore, it was demonstrated that the glass-ceramic method is suitable to obtain materials with controlled microstructure. The microstructural variation caused an increase of up to two times in total ionic conductivity. Thus, it was concluded that aliovalent substitutions promote greater increases in ionic conductivity of NASICON materials than those obtained by changes in the grain size.
Aplicação de modelos lineares mistos com regressão quantílica na projeção do crescimento e produção de Eucalyptus spp.
(Universidade Federal de São Carlos, 2020-04-03) Almeida, Alessandro Araujo Amaral de; Thiersch, Cláudio Roberto; https://lattes.cnpq.br/8791966697254106; https://lattes.cnpq.br/4552102821208040
The correct inference of growth and forest production are important factors for decision making in planning, with different models based on regression statistics. These models are used to determine the technical and economic age of the cut, to generate production tables for the stands and growth curves. Due to its importance and the search for more accurate estimates, the development of more complex models has been applied in the forestry sector, among which we can mention the mixed modeling and the use of quantile regression. The aim of this work was to evaluate the use of a new technique using linear mixed models with quantile regression in the projection of growth and production in an eucalyptus stand and also to compare the volumetric estimates with those obtained by the traditional Clutter model and mixed modelling. The data came from a clonal Eucalytpus spp. stand, located in the interior of São Paulo state, aged between 24 and 64 months. Adjustments to the equations of the Clutter model, as well as the mixed-effect models and the linear mixed-effect models with quantile regression, as well as the linear mixed model with quantile regression and mixed-effect models were performed using the statistical software R. To check the accuracy of the methods, the last measurement was selected as a reference and, based on this, classes of projection periods were created at 12-month intervals, which are: (6,18], (18,30] and (30,42] months. The evaluation was carried out through the residual plot, as well as through the square root of the average error (RMSE %). It was found that the mixed model and linear mixed model with quantile regression obtained a lower RMSE of 3.94% and 4.20%, respectively, for (6,18] month class. For the classes (18.30] and (30.42) months, the traditional Clutter model that presented lower values of RMSE, being 4.28% and 4.75%, respectively. After the analyzes were carried out, it was defined that for the class of (6,18) months the use of the linear mixed model with quantile regression due to the RMSE is indicated and also present the best dispersion of the residues. For the classes (18,30] months, despite the traditional Clutter model presenting the lowest RMSE, after analyzing the dispersion of the residues it was found that the use of the mixed model is the most suitable due to better dispersion, and for the class of ( 30,42] months, the traditional model of Clutter is the most suitable.
Estudo do método de obtenção de membranas assimétricas de polietersulfona contendo complexos de polieletrólitos
(Universidade Federal de São Carlos, 2020-04-03) Vale, Rayane da Silva; Silva, Caio Marcio Paranhos da; https://lattes.cnpq.br/7793686262868668; https://lattes.cnpq.br/9352007529619570
Compared with traditional separation methods, polymeric membranes have low operation cost, fast separation rate and versatility. One interesting way of changing membrane properties is mixing additives into the polymeric matrix. Polyelectrolytes complexes (PECs) (polyelectrolytes combined via electrostatic interaction) are a good material for that due theirs hydrophilicity, tunable surface charge, stable structures and insolubility in common solvents. Based in this context, inversion phase membranes containing PECs were obtained through three different methodologies: in situ, post crosslink and simultaneously crosslink. The chosen polyelectrolytes were 4-fluorophenyl sulfone terminated poly(diallylpiperidinium hexafluorphosphate) (PDApipPF6) and sulfonated poly(ethylene terephthalate) (SPET). The polymeric matrix used was polyether sulfone, known for its good mechanical strength and high temperature stability. Analysis by fourier transform infrared spectroscopy confirmed the presence of SPET in the PEC membranes, while the presence of PDApipPF6 was confirmed by positives values of zeta potential. Scanning electron microscopy images of the cross-section of the membranes were similar and showed asymmetric structure consisting of a dense skin and porous sub-layer. The increase of water vapor permeability and the decrease of water contact angle of the PEC membranes indicated that the presence of the complexes alters the membranes’ hydrophilic profile. Differences in the curves of the thermogravimetric analysis showed that depending on how the PECs are obtained, the interaction between the PELs changes, which produces membranes with different thermal behaviors. The results of filtration and adsorption of remazol red also varied with the methodology.