Navegando por Data de Publicação, começando com "2017-08-04"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 6 de 6

Efeitos da diminuição do tamanho médio de partículas da frita nas propriedades dos esmaltes cerâmicos visando aplicação na esmaltação digital
(Universidade Federal de São Carlos, 2017-08-04) Nieves, Leidy Johana Jaramillo; Melchiades, Fábio Gomes; https://lattes.cnpq.br/4469106561041487; Boschi, Anselmo Ortega; https://lattes.cnpq.br/3259846931278607; https://lattes.cnpq.br/2449303173101918
Nowadays Brazil is the second largest producer and consumer of ceramic tiles in the world. In the process of tile’s production, the decoration and glazing play a prominent role since they are responsible for technical and aesthetic properties of the product. Ceramic tile decoration underwent a revolution with the arrival of ink-jet technology. This technology has also started to become a focus of interest for glazing, creating the possibility of having a completely digital line in the manufacture processing. Accordingly, glazes must be adapted to requirements of this new technology. Among them, the particle size of the suspensions employed in the ink jet technology should be lower than that used in traditional glazes. In this context, this project evaluates the effect of the average particle size reduction on the properties of glazes, from their preparation, application, sintering and final product. The methodology of the project consisted in using an industrial frit applied to transparent glazes. The frit was ground to obtain four different granulometry particle sizes for the preparation of glazes. The materials were characterized by rheological analysis, applied layer and their interaction with digital inks. Finally, the sintering process and the characteristics of the fired product were monitored. The study showed that the main effect of the decrease in particle size was on the particle size distribution curve, which affected the packing of particles and this, in turn, affects the pore structure which affects the packing of the suspension, That is, rheological behavior and the characteristics of the applied layer of the glazes, showing that changes in the applied layer affected the subsequent stage as the decoration and the firing.
Desenvolvimento de materiais mesoporosos baseados em sílica oriunda de biomassa para utilização como sistema remediador de hidrocarbonetos policíclicos aromáticos
(Universidade Federal de São Carlos, 2017-08-04) Costa, José Arnaldo Santana; Silva, Caio Marcio Paranhos da; https://lattes.cnpq.br/7793686262868668; https://lattes.cnpq.br/5913578662870885
This work describes the synthesis and characterization of mesoporous materials from the use of amorphous silica extracted from rice husk ashes (RHAs), as well as the preparation of mixed matrix membranes (MMMs) using the mesoporous materials as filler materials to be used in the remediation of the polycyclic aromatic hydrocarbons (PAHs). The mesoporous materials were synthesized by the hydrothermal method and the MMMs by casting. It was possible to observe that the acid treatment did not alter the molecular structure of the RHSs, as well as there was an increase in the percentage of SiO2 in the thermal stability. The RHAs presented an amorphous silica nature, with the characteristics of a fine powder of white color, with type IV isotherms and H1 type hysteresis, and high surface area values. The hydrothermal method was efficient in the synthesis of the mesoporous materials, which presented TGA curves and characteristic bands of the formation of the amorphous condensed silica framework, typical of mesoporous materials of the M41S family, with high surface area. The casting method was efficient for the preparation of the MMMs, which showed a good dispersion of the mesoparticles incorporated, small-angle ordering and a small increase in the Tg values of the MMMs with the incorporation of the MCM−41−NH2 (CCA). The adsorption tests showed that there was an increase in the adsorbed amount (qe) with the increase of the initial concentration of the HPAs, adsorbent amount, contact time, and temperature, however pH variation was not significant. The adsorption kinetics was relatively fast and followed the non-linear pseudo-second order model, and the isotherms obtained were more adequate to the theoretical Langmuir model. The values of qe found for the mixture of HPAs Naf, B[b]F, B[k]F, and B[a]P were in the same order of magnitude for all adsorbent materials tested: Naf < B[a]P < B[k]F < B[b]F due to the hydrophobic effect. The transport properties were more influenced by the incorporation of the MCM−41−NH2 (RHA) into PSf−Ac than the addition of the PABA−MCM−41 (RHA) in PES, as the best results of the rate of permeation, rate of retention, and percentage of removal were obtained for the MMMs based on PSf, however the pure PSf and PES membranes presented similar results.
Ações pública e privada no processo de ocupação de Ribeirão Preto: do núcleo Antônio prado a atuação do GDU Grupo de Desenvolvimento Urbano
(Universidade Federal de São Carlos, 2017-08-04) Melo, Rose Elaine Borges de; Silva, Ricardo Siloto da; https://lattes.cnpq.br/5346985934880710; https://lattes.cnpq.br/8602449876992473
The work studies the performance of the different agents of the real estate market in the process of occupation of the South sector, located in the geographical periphery of the Ribeirão Preto´s City, from 1990 to 2010. The study was based on the analysis of the actions of the productive agents of the real estate market, especially the UDG Urban Development Group (association of builders, developers and land owners) and actions of the municipal public power as a regulator of urban space. In this way, we analyze: the legislation through the urbanistic instruments of control of land use and occupation; Programs, urban projects and master plans through the concepts and guidelines used in the production and organization of urban space (occupation pattern, growth guidelines and urban structure); Public services through the implementation of infrastructure and urban equipment; And, allotments and condominiums horizontal and vertical through the projects approved in the Secretariat of Planning and Public Management of Ribeirão Preto. The results verify the hypotheses that guided the accomplish of this research: 1) in addition to socioespatial segregation center periphery, from its beginnings, the process of formation and expansion of Ribeirão Preto´s City presents a pattern of occupation where the high income population predominates in the southern region and the population of Low income in the north of the city 2) real estate agents such as developers, real estate developers and landowners, among others, acted in an organized way in the process of occupation of the South sector, located in the geographical periphery of the city of Ribeirão Preto, in the Period from 1990 to 2010 becoming the effective planners of this urban space.
Correlações entre microestrutura, parâmetros térmicos e propriedades mecânicas de ligas de alumínio da série 5xxx solidificadas unidirecionalmente
(Universidade Federal de São Carlos, 2017-08-04) Ogata, Cínthia Toshimi; Ishikawa, Tomaz Toshimi; https://lattes.cnpq.br/5726055117451807; Spinelli, José Eduardo; https://lattes.cnpq.br/8882038118634925; https://lattes.cnpq.br/3094235761366663
Processing high-Mg content Aluminum Alloys by continuous casting technics is considered an industry challenge. The present research aims to characterize 5xxx alloy series, considering composition based on the commercial alloy 5052 with different Mg contents (2.4wt.%, 2.6wt.% and 3.2wt.%, the latter intentionally extrapolated from the maximum limit) through transient directional solidification experiment. The results allowed to comprehend the effect of Mg content with respect to thermal parameters (cooling rate and VL- tip growth rate), microstructural parameters (primary and secondary dendritic spacing - Ai and À2) and mechanical properties (Brinell hardness) of different alloys. Microstructural analyzes were performed using polarized light microscopy and scanning electron microscopy (SEM) of samples taken from different ingot positions (between 3mm and 110mm from the water-cooled face). The experiments reached cooling rates between 7 and 30°C/s (considering the closest thermocouple to the bottom). The experimental growth law for microstructural evolution of Ai were obtained, resulting in: À1 = 640 TL 1/4 to the alloy with 2.4wt.%Mg and À1 = 300 TL 1/4 to the sample with 3.2wt.%Mg, in which experimental the exponent -1/4 is in agreement with the expression proposed by Jackson and Hunt modified by the analytical model of Garcia and Clyne. Secondary dendritic growth laws were also obtained concerning their variation with the growth rates, resulting in the following expressions:X2 = 27 VL-11 for the 5052-2.4wt.%Mg and X2 = 15.0 VL-11for the 5052-2.6wt.%Mg and 5052-3.2wt.%Mg* alloys. Thus, 5052 alloys containing higher Mg content may allow a significant decrease on X2 value for a certain VL. The hardness values were directly related to the size and distribution of the intermetallic particles and showed À2 as the main variable to affect mechanical properties for the tested alloys.
Novas abordagens na síntese de heterociclos com potencial aplicação na síntese de moléculas bioativas
(Universidade Federal de São Carlos, 2017-08-04) Alves, Tânia Mara Ferreira; Ferreira, Marco Antonio Barbosa; https://lattes.cnpq.br/6874055640224407; https://lattes.cnpq.br/2711137157839870
Cobalt-catalyzed oxidative cyclization of gem-disubstituted conjugated alkenols: In this part of the work we applied the Mukaiyama Oxidative Ciclization under oxidative and reduced termination conditions aiming the preparation of trisubstituted 2,5,5-THFs-trans from gemdisubstituted aromatic conjugated olefins with different electronic properties. The THFs were obtained only under reduced termination conditions, with of 32-44% of yields. Under oxidative termination conditions, only products from secondary radical reactions that competed with the oxidative cyclization reaction were observed. In addition, the diastereoselectivity involved in this process was evaluated,, which in this case were obtained in 17-46% of yields and dr 2.5:1 to 5.4: 1. Preparation of 1H-1,2,3-triazole under more sustainable conditions: In this second part of the work the main objective was to develop an one-pot methodology for the preparation of 1H-1,2,3-triazoles from nitrolefins. This methodology is inserted in a concept of a more sustainable chemistry, since the obtaining heterocyclics was carried out through a metal-free approach, using the green solvent PEG400, and the direct use of sodium azide. The 1H-1,2,3-triazoles were obtained via one-pot reaction in good yields (54-80%).
Filtragem automática de opiniões falsas: comparação compreensiva dos métodos baseados em conteúdo
(Universidade Federal de São Carlos, 2017-08-04) Cardoso, Emerson Freitas; Almeida, Tiago Agostinho de; https://lattes.cnpq.br/5368680512020633; https://lattes.cnpq.br/7714557242920689
Before buying a product or choosing for a trip destination, people often seek other people’s opinions to obtain a vision of the quality of what they want to acquire. Given that, opinions always had great influence on the purchase decision. Following the enhancements of the Internet and a huge increase in the volume of data traffic, social networks were created to help users post and view all kinds of information, and this caused people to also search for opinions on the Web. Sites like TripAdvisor and Yelp make it easier to share online reviews, since they help users to post their opinions from anywhere via smartphones and enable product manufacturers to gain relevant feedback quickly in a centralized way. As a result, most people nowadays trust personal recommendations as much as online reviews. However, competition between service providers and product manufacturers have also increased in social media, leading to the first cases of spam reviews: deceptive opinions published by hired people that try to promote or defame products or businesses. These reviews are carefully written in order to look like authentic ones, making it difficult to be detected by humans or automatic methods. Thus, they are used, in a misleading way, in attempt to control the general opinion, causing financial harm to business owners and users. Several approaches have been proposed for spam review detection and most of them use techniques involving machine learning and natural language processing. However, despite all progress made, there are still relevant questions that remain open, which require a criterious analysis in order to be properly answered. For instance, there is no consensus whether the performance of traditional classification methods can be affected by incremental learning or changes in reviews’ features over time; also, there is no consensus whether there is statistical difference between performances of content-based classification methods. In this scenario, this work offers a comprehensive comparison between traditional machine learning methods applied in spam review detection. This comparison is made in multiple setups, employing different types of learning and data sets. The experiments performed along with statistical analysis of the results corroborate offering appropriate answers to the existing questions. In addition, all results obtained can be used as baseline for future comparisons.