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Observações atípicas em alta dimensão
(Universidade Federal de São Carlos, 2022-09-15)
Hisatugu, Matheus Toshio
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Andrade Filho, Mario de Castro
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https://lattes.cnpq.br/6518161034709249
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https://lattes.cnpq.br/0565444239927400
Outliers and heteroskedastic noise are two common situations in Statistics. Nowadays the amount of generated data is very high and for this reason it is possible to find high dimensional data (the dimension d is just as large or larger than the number of observations n). Furthermore, it is possible that the data have heteroskedastic noise, which means that the noise variance can be different entrywise. Principal component analysis is a technique that aims to create a subspace with lower dimension than the original space. The technique is used in different areas such as Statistics, Econometrics, Machine Learning and Applied Mathematics. Choi and Marron (2019) introduced a new notion of high dimensional outliers that embraces other types and also investigates the behaviour of these outliers in the subspace created by the principal components analysis. Most of the techniques used in this context are based on the assumption of homoskedastic noise. However, as mentioned before, it is known that this is not always the case. Therefore, Zhang, Cai and Wu (2022) proposed a new method called HeteroPCA, which main objective is to remove the bias of the main diagonal of the sample covariance matrix due to heteroskedasticity. In this work, the main objective is to combine the method proposed by Zhang, Cai and Wu (2022) and the methodology proposed by Choi and Marron (2019) to find a subspace capable of identifying the presence of outliers when heteroskedasticity noise is present.
Embalagens antioxidantes como impulsionadoras da intenção de compra de produtos alimentícios
(Universidade Federal de São Carlos, 2022-09-15)
Silva Júnior, Hélio Álvaro Pires da
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Otoni, Caio Gomide
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https://lattes.cnpq.br/9403804691367376
Knowing that, among other factors, the packaging exerts great influence on the intention to purchase food products, this study investigated whether the antioxidant active packaging can be determinant in the consumer's decision to purchase the product or not. Qualitative research was carried out, by means of a free-access form, disseminated in social networks and by e-mail, to map the consumer behavior in relation to the consumption of products packaged in antioxidant systems. It was found that, of the 141 responses obtained, 55 consumers (39% of the sample population) have individual monthly income between one and two minimum wages, and only 21.3% of the respondents were aware of the antioxidant packaging. Thus, it was evident that the factor of price increase in food products with this technology was the main deterrent in the purchase decision, however, the little knowledge of the population about antioxidant packaging and its functions also made it difficult to consider buying food products packaged with antioxidant technology.
Estudo do efeito de aditivos a base de zinco para a sinterização a frio do óxido de zinco
(Universidade Federal de São Carlos, 2022-09-15)
Toledo, André Sanchez de
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Pandolfelli, Victor Carlos
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https://lattes.cnpq.br/7369376873984839
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Muche, Dereck Nills Ferreira
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https://lattes.cnpq.br/6542991023278848
Atualmente, o processamento e obtenção de um óxido cerâmico denso e funcional são extremamente custosos para as indústrias deste ramo, envolvendo o dispêndio de uma enorme quantidade de energia para sinterizá-los, e necessitando do aquecimento das matérias-primas a temperaturas superiores a 1000-1500 ºC. Neste contexto, surgiu em 2016 uma nova técnica de sinterização de ultra-baixa energia (< 350ºC) chamada Sinterização a frio, que entre outras vantagens, reduz o custo energético de processamento de óxidos, permite uma maior integração entre diferentes materiais inorgânicos e facilita o controle microestrutural do pó sinterizado. Da literatura, podemos listar algumas das vantagens desta técnica em comparação aos processos convencionais de sinterização: i. Por meio de uma análise tecno-econômica dos processos de sinterização utilizados atualmente, Ibn-Mohammed et.al [20] concluiu que a técnica de sinterização à frio apresenta alto potencial econômico e competitividade devido ao baixo investimento envolvido. Pereira da Silva et.al [21] reforçou que a sinterização à frio, em comparação à técnicas como a Sinterização por faísca de plasma e a Sinterização convencional apresentou redução de 40 e 50% de energia respectivamente; ii. Integração entre diferentes materiais inorgânicos: Composições que exibem janelas de densificação limitadas podem ser co-sinterizado em um único monólito [2]; iii. Integração entre diversos tamanhos de grão e estruturas: Microestruturas que pode apresentar macro-, micro-, e nano-grãos podem ser preparados em uma única etapa [2]; iv. Compósitos orgânicos e inorgânicos podem ser preparados em um processo de uma única etapa. As temperaturas extremamente baixas são compatíveis com diversos polímeros [2]; v. Oportunidade de explorar os mecanismos e princípios da técnica, desenvolvimento conhecimento científico e de engenharia para moldar uma nova infraestrutura de produção/síntese de materiais [2].
Implementação de uma arquitetura para minerar regras de associação espaciais a partir de dados espaciais fuzzy
(Universidade Federal de São Carlos, 2022-09-15)
Felix, Thiago Deschamps Reis
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Carniel, Anderson Chaves
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https://lattes.cnpq.br/6350698053529179
The use and importance of spatial data have been growing more and more. With the assimilation of the real world, many spatial phenomena are modeled and represented by fuzzy spatial objects, which have blurred interiors, uncertain boundaries and/or inexact locations. Inferring rules and finding patterns is something that human beings have always done, with the advancement of Artificial Intelligence and the representation of a spatial object, this work proposes an implementation of an architecture capable of mining spatial association rules from fuzzy spatial data. With user input as a parameter, the proposed architecture discovers patterns of spatial association between spatial objects of interest to users (e.g. tourist attractions) and such fuzzy spatial features (e.g. sanitary conditions of restaurants, number of reviews and price of accommodations). Furthermore, this work presents a case study based on real datasets that shows the applicability of the developed method.
Multiplicidade de padrões voluntários de sustentabilidade na exportação global de café
(Universidade Federal de São Carlos, 2022-09-15)
Beltrame, Nicole
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Faria, Rosane Nunes de
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https://lattes.cnpq.br/1172221536399083
In the global dynamics of coffee exports, the Sustainability Standards (SS) have been created since 1980, aiming at assigning criteria and requirements to be met by agents who pass through social, environmental, governance, equity, etc. However, adherence to the SS incurs costs so that agents are in compliance and can access specific markets and maintain the established commercial relationships. Furthermore, the increasing number of new standards worldwide created duplicity and overlapping criteria adopted by these standards and intensified competition between them. This effect is called the Multiplicity of Sustainability Standards. The objective of this work is to analyze the landscape of the multiplicity in the coffee market, considering the most significant coffee exporting countries in the world (Brazil, Vietnam, Colombia, Honduras and India) from the analysis of overlap (SOI) and competition (HIS) of standards and also the combination between them. For this, eight SS have been selected: Common Code for the Coffee Community (4C), Coffee Sustainability Reference Code, Rainforest Alliance, FairTrade, FairTrade Small Producers, UNCTAD, Small Producers Symbol and IFOAM. For each sustainability standard, requirements are assigned to be met for its adherence, including environmental, social, human and women's rights requirements and best practices for land and water use, among others. These requirements allow us to calculate the indices mentioned above. From this, it is possible to analyze the dynamics between sustainability standards, their competitive strength and the degree of overlap compared to other standards.
Reconhecimento de entidades nomeadas aplicado em prontuários médicos
(Universidade Federal de São Carlos, 2022-09-15)
Souza, Thais Cristina Cardozo de
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Viola, Márcio Luis Lanfredi
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https://lattes.cnpq.br/7797241339089177
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https://lattes.cnpq.br/5731362370639869
A named entity is a real-world object, such as a person (e.g. Alan Turing), a location (e.g. London), or an organization (e.g. UFSCar). Named Entity Recognition (NER) is a subarea of Natural Language Processing (NLP) whose purpose is to identify various named entities that appear in text. This work proposes to detail the steps for the use of Named Entity Recognition. Its applicability is demonstrated in real anonymized medical records that contain textual information about patients.
Seleção de áreas para implantação de estruturas de passagem de fauna através da avaliação da conectividade funcional da paisagem
(Universidade Federal de São Carlos, 2022-09-15)
Silveira, Patrícia Batista da
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Tonello, Kelly Cristina
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https://lattes.cnpq.br/3844965971290638
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https://lattes.cnpq.br/4738150382976999
In the search for new habitats in a fragmented landscape, animals tend to follow paths through the most permeable matrices, known as least-cost paths (LCP). Some approaches consider the least-cost paths as the ecological corridors of a landscape, such as this study. However, during their movement through the landscape, animals are faced with linear anthropic barriers that restrict their movements, such as highways and railroads. The wildlife crossings structures then appear in this context as punctual elements artificially installed in the landscape, in places where these road barriers exist, to restore or increase the biological flow and connectivity in that region. But what is verified in the great majority of cases is the installation of these structures of wildlife crossings just as a late remediation, only in some places where high numbers of road kills of wild animals are checked. This study presents a methodology for the prior identification of sites for the installation of structures for wildlife crossings, as part of the sustainable road planning of a landscape, through the joint analysis of the ecological corridors of animals (LCP) and road structures in a region. The area selected for this study was a geopolitical unit located in the Serra da Mantiqueira, in the Atlantic Forest domain, in the State of São Paulo, Brazil. Forty-four points were identified in the study area that demand the installation of wildlife crossings and/or other mitigation measures for fauna accidents. This study also questions the use of high resistance values for highways and railroads in ecological corridor softwares (for the LCP mappings), and suggests a different approach in the tabulation of the resistances of these road structures, with the use of lower values for these structures, for the identification of the true paths of fauna movement in a landscape - and consequently, the location of the real points where the implementations of wildlife crossings will be needed.
Desenvolvimento de um mecanismo de proteção contra a instalação de módulos maliciosos no kernel Linux baseado em syscall hooks.
(Universidade Federal de São Carlos, 2022-09-15)
Colombo, Víctor Cora
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Guardia, Hélio Crestana
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https://lattes.cnpq.br/1780902767520967
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https://lattes.cnpq.br/9240836918433079
Even though the Linux kernel is categorized as being monolithic, it has the capability of extending its functionalities by adding code through modules that are added during runtime. Due to its importance, Linux is a preferential target for a high number of ill-intentioned hackers seeking to perform high impact attacks targeting these computer systems. The feature of easily adding code to the kernel using modules draws the attention of these hackers, whom seek to install programs known as kernel rootkits aiming to infect the operating system. This work will propose a new way to prevent rootkits from infecting a Linux system, without the need to recompile the kernel or reboot the machine. This is done through the use of module signing and cryptographic keys. The result will be a module that, when loaded into the system, should prevent the installation of other modules that have not been signed by the real system administrator. This module and other auxiliary tools will help to sign and verify them when the installation is performed.
Sensibilidade de plantas cultivadas ao dicamba e 2,4-D aplicados em doses comerciais e subdoses
(Universidade Federal de São Carlos, 2022-09-15)
Boteon, Beatriz Fogolari
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Monquero, Patricia Andrea
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https://lattes.cnpq.br/2766526793830455
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https://lattes.cnpq.br/9596339813627049
The development of crops resistant to dicamba and 2,4-D may reflect the intensive use of these herbicides in agricultural areas, including close to susceptible species. Therefore, the objective of this work was to evaluate the sensitivity of bean, peanut and cotton crops to different doses of dicamba and 2,4-D. The experiments were isolated and conducted in a greenhouse in a completely randomized design with four replications in a 2 x 8 +1 factorial, with two herbicides, 8 doses and a control without application. Bean, cotton and peanut plants were submitted to different doses of 2,4-D with 670 (commercial dose); 335; 167.5; 83.75; 41.87; 20.93; 10.46 and 5.23 g a.i. ha-1 and dicamba at doses 560 (commercial dose); 280 ;140; 70; 35 ;17.5; 8.75 and 4.37 g a.i. ha-1 when they had the second pair of true leaves. Phytotoxicity assessments were performed at 5, 10 and 15 days after application (DDA). At 15 DAA, the leaf area of the plants was evaluated and the dry biomass of the aerial part was removed. In the cotton crop applied with 2,4-D up to the dose of 83.75 g a.i. ha-1 showed 80%, from 20.93 g a.i. ha-1, it did not present phytotoxicity. For the bean crop sprayed with 2,4-D, doses of 670 and 335 g a.i. ha-1 caused the highest levels of injury (up to 95%). From the dose of 167.5 g a.i. ha-1 they also caused injuries, even at the lowest dose of 5.23 g a.i. ha-1 . Plants sprayed with dicamba caused plant death at doses 560; 280; 140; 70; 35 g a.i. ha-1 , and even at the lowest doses (17.5; 8.75 and 4.37 g a.i. ha-1 ) showed 80% to 70% phytotoxicity, respectively. In peanut, the dose of 670 g a.i. ha-1 of 2,4-D showed 60% phytotoxicity, being the highest. The doses of 20.93; 10.46 and 5.23 g a.i. ha-1 did not show any phytotoxicity. Peanut plants sprayed with dicamba showed up to 70% at the dose of 70 g a.i. ha1 . Only the dose of 4.37 g a.i. ha-1 did not present any injury. It is necessary to pay attention to the use of these herbicides when applied close to the crops, because in sub-doses toxic effects were verified in the plants.
Mapeamento de parâmetros de soldagem robotizada GMAW visando tempos de produção reduzidos para juntas do aço ASTM A572 G50
(Universidade Federal de São Carlos, 2022-09-15)
Arbex, João Renato
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Åstrand, Erik
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Spinelli, José Eduardo
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https://lattes.cnpq.br/8882038118634925
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https://lattes.cnpq.br/3941102917523821
The welding process using electric arc with shielding gas (GMAW - Gas Metal Arc Welding) is extremely widespread and used in several applications. This is due to its high productivity combined with low cost in addition to its suitability to high automation level. The technology development for an already traditional process is supported by constant demands. One of the most important is related to increase productivity in the industry so that achieving higher filler material deposition rates. Increasing the travel speed in welding process is one of the most straight through and effective ways to meet this demand. However, as the commonly available processes reach a limit, there is a need of recent technologies to overcome such limitations. As such, for any innovative technology there are challenges to be overcome, which require studies to understand its operation and application in a way that promotes the desired results without compromising the required quality. The goals of this work are increase the welding travel speed so that the cycle times could be reduced. The starting point is to understand the initial state and conduct tests, aiming at achieving high travel speeds through the variation of welding parameters, followed by visual and macrographic analysis looking for defects and meeting specifications of the joints. Changing process from standard pulsed arc to PMC results on a 50% increase on welding travel speed which means an average 32% reduction on process time on the studied case.
Estudo da formação de fase vítrea no sistema Fe-Mo-P-C-B utilizando cálculos termodinâmicos e critério de amorfização
(Universidade Federal de São Carlos, 2022-09-15)
Martins, Droanna Rosa
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Araújo, Aylanna Priscila Marques de
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https://lattes.cnpq.br/1742937906045551
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Gargarella, Piter
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https://lattes.cnpq.br/4641435644243916
Glasses with high atomic concentration of iron have been studied due to its magnetic properties, high mechanical and corrosion resistance, and low cost of the raw material. However, these materials present low glass-forming ability phase formation and low plastic deformation capability, which make them difficult to produce and with limited application. The objective of the present study is to use the the criterion (λmin + ∆ℎ) to investigate the glass-forming ability of glassy phase of the Fe-Mo-P-C-B system and associate it to the results of thermodynamics calculations to understand the formation of primary phase and liquidus temperature of alloys. The criterion of glassy phase formation (λmin + ∆ℎ) was applied to composition of alloys with a total percentage of metalloid elements from 17 to 25% at.. All the possible concurrent phases of the glassy phase were found in literature. All the binary, ternary, quaternary, and quinary possibilities were considered. The alloys selected from the criterion of glassy phase formation were better investigated by using the CALPHAD method by the software Pandat. During the selection of the compositions, the minimum Fe atomic concentration considered was at 60%. The increase of the percentage of metalloids in the Fe-Mo-P-C-B system raises the capability of glassy phase formation of the alloy. From a metalloid atomic percentage of 23% the capability of formation of glassy phase doesn't change significantly. No investigated composition had a phase with ductile character as primary phase. The liquidus temperature of the alloys is lowered with the increase of the percentage of metalloids, and decreases even more to higher Fe concentration. Based in the results of the criterion used in the present study, the capability of glass phase formation, liquidus temperature, and the phases formation, three alloys from the Fe-Mo-P-C-B system presented to be promising to be experimentally investigated: Fe77Mo6P8C7.5B1.5 (17% metalloid), Fe77Mo5P9C7.5B1.5 (18% metalloid), Fe77Mo3P11C7.5B1.5 (20% metalloid).
Uso de cadeias de Markov para identificar atribuições em mídias digitais
(Universidade Federal de São Carlos, 2022-09-15)
Carvalho, Raquel Malheiro de
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Viola, Márcio Luis Lanfredi
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https://lattes.cnpq.br/7797241339089177
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ttp://lattes.cnpq.br/7237492273036557
With the advancement of digital marketing and the rise of new paid media channels for running campaigns and ads aimed at selling products, many advertisers question the use of media that do not directly lead to conversions, meaning the user does not convert through them. Therefore, statistical methods can be employed to identify the role of each media channel in conversions, considering user behavior leading up to the conversion. In this work, Markov Chains are used as a method to analyze user behavior in digital media by estimating user conversion probabilities.
Racismo científico: o eu, o outro e o nós: práticas para o ensino de biologia
(Universidade Federal de São Carlos, 2022-09-15)
Pitanga, Letícia Pitelli
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Calzolari Neto, Anselmo João
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https://lattes.cnpq.br/4906309581958797
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https://lattes.cnpq.br/9385346003046029
This Academic Work aims to propose, from the theme of Scientific Racism, the elaboration and analysis of a didactic sequence that can address racism and science as points to understand promote the teaching for Ethnic-Racial Relationships, in line with the brasilian law 10.639/2003, possibilite understand historically what are the social implications, that this violence has created and how we can overcome it through genetics, content addressed in biology education for the 2nd year of high school. As a way of structuring the didactic sequence, we will use the methodological proposal of “The Three Pedagogical Moments” considering Dialogical Learning that from it is principles, promotes learning through dialogue and social transformation, together withSuccessful Educational Actions, specifically Dialogical Reading and Interactive Groups as part of the activities proposed below.
Uso da música para alunos com Transtorno do Espectro do Autismo na sala de recursos multifuncionais: revisão narrativa
(Universidade Federal de São Carlos, 2022-09-15)
Rodrigues, Rhayane Fernandes dos Santos
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Elias, Nassim Chamel
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https://lattes.cnpq.br/4216525883778695
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https://lattes.cnpq.br/5316620076016991
This study had as its principle the bibliographic review of works related to the use of music for people diagnosed with Autism Spectrum Disorder, by teachers in the multifunctional resource room. Thus, we sought to analyze the literature and discuss the narratives of what has been shown in research relevant to the subject. Of a bibliographic nature, the work was developed from the search in the databases of the Scientific Electronic Library Online (SciELO), CAPES Periodicals Portal and the Brazilian Digital Library of Theses and Dissertations (BDTD). Four studies were found that address the theme Autism Spectrum Disorder and music, in addition to listing the main benefits of its use, however, no research was found that related the use of music in multifunctional resource rooms. Thus, the findings show the most diverse gains in the development and behavior of individuals with Autism Spectrum Disorder when methodologies are implemented that use music as a form of repertoire promotion, however, the lack of research that studies the performance of professionals in multifunctional resource rooms that appropriate music in their approach and intervention. Thus, there is a need for more research in this area.
Quimiometria aplicada à análise de embalagens plásticas na indústria alimentícia
(Universidade Federal de São Carlos, 2022-09-15)
Almeida, Heloísa Nascimento de
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Pereira Filho, Edenir Rodrigues
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https://lattes.cnpq.br/3394181280355442
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https://lattes.cnpq.br/6863627506038561
Most of the packaging used in the food sector is produced in plastic materials that can be flexible or rigid. Rigid packaging such as high-density polyethylene is highlighted because they keep their shape independent of the characteristics of the stored product, however, under certain conditions, they are susceptible to deformation during storage, transport, and stacking. Therefore, in order to evaluate a possible decrease in the weight of the packaging aiming at productivity aspects, chemometric tools were used to understand how the storage temperature and the weight of the packaging affect in the resistance to compression and deformation. With the application of statistical tools such as Pearson coefficient, variance analysis and Tukey test it was possible to verify that the temperature and the weight of the packaging influence the mean of resistance, however only weight is a statistically significant factor for the mean of deformation.
Academias ao ar livre: uma revisão sistemática
(Universidade Federal de São Carlos, 2022-09-16)
Donadoni, Vitor Monti Carmelo
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Oliveira, Maria Carolina Derencio
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https://lattes.cnpq.br/8887606484271737
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https://orcid.org/0000-0002-7816-7412
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Ramos, Glauco Nunes Souto
Introduction: Outdoor Gyms (OG) were developed for local public squares and parks, with the aim of giving the population access to the practice of physical activity focused on health and well-being. As it is implementation has been disseminated throughout the world year after year, this study sought to understand, based on various academic productions, what is already known about the users to this space, how the equipments are used, whether there is professional guidance on site, among other investigations explored in the OG. Objective: To gather academic research associated with OG, developed both in Brazil and in other countries, in order to systematically expose and compare the information present in the literature. Methods: The selection of studies was carried out in six databases (Cochrane Library, PubMed, LILACS, Web of Science, Scopus and Scielo), with no fixed initial period until May 2022, using the research term: outdoor gym AND health gym AND physical education. Subsequently, the studies that met the previously established inclusion criteria were maintained. Results: In the end, 17 studies were included and allocated according to their similarities, resulting in the construction of the following categories: users profile; location effectiveness; physical activity level; systematic reviews. The following isolated categories also emerged: teaching strategies; professional performance; equipments use; physical structure. Conclusion: Literature analyzes indicate that there is still no characteristic users profile of OG, but that the low-income population is the one that most uses the equipments. It is necessary that there are Physical Education professionals in the OG, so that this population can receive adequate guidance, perform physical activities reaching satisfactory levels and feel more encouraged to adhere to their practices in the OG.
Programação de um módulo de business intelligence no Block-Based Integrated Platform for Embedded Systems (BIPES)
(Universidade Federal de São Carlos, 2022-09-16)
Pacheco, João Victor
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Santos, Marilde Terezinha Prado
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https://lattes.cnpq.br/9826026025118073
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https://lattes.cnpq.br/0750828452697511
With the modernization of technologies and the activities of the society, the decision-making process starts to depend on the analysis of increasingly larger data sets. The increase in the use of the internet, the emergence of the Internet of Things and the popularization of Big Data, affect in a expressive way, the increase in the generation of high volumes of data with greater variety at high speed.This lead the demand for more complex tools that allow companies to become more Data Driven, which means to have their processes, decision-making and strategic planning based on data. In this context Business Intelligence tools emerged, being able to organize and delivery well-structured ways to manipulate, analyse and visualize those data. The Block-based Integrated Platform for Embedded Systems (BIPES) is a platform that allows the no-code development for embedded systems, empowering users to develop solutions using programming blocks. Most solutions developed using BIPES are related to sensor data collection, and so far, the platform offer tools for real-time analysis of the data, however it does not offer a way to analyze large volumes of historical data. BIPES users, in a visual and easy way, cannot extract insights and make decisions that impact all the scope of the project. Thus, this present work proposes to develop, using BI tools, a module capable of assisting in the analysis of sensor data and the decision-making processs, which can be integrated with the BIPES. For this purpose , a dashboard was developed using the Tableau Desktop tool, capable of present the historical behavior and forecasting, device performance ranking, nonconformity alert, behavior throughout the day, outilers presence, and indicators of daily average and total results.
Inferência da conectividade neuronal e o modelo de Galves e Löcherbach
(Universidade Federal de São Carlos, 2022-09-16)
Schiavone, Vitor Gomes
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Pena, Rodrigo Felipe de Oliveira
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https://lattes.cnpq.br/6663640683388672
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Ferreira, Ricardo Felipe
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https://lattes.cnpq.br/2355076087945221
One of the most important issues in neuroscience is to understand the dynamics of animal behavior, that is, the joint action of large numbers of neurons, body parts, and the environment. The relationship between this behavior and the way that neurons interact with each other is a challenging question, since real experiments only have access to a small part of the neural system. Alternatively, generic mathematical models are considered to describe this phenomenon. In this work, the activity of each neuron is represented by a discrete-time stochastic process, whose random variables indicate whether or not there was a neuronal spike at a given instant of time. For each neuron, the probability of observing a neuronal spike at a given instant of time depends on the evolution of presynaptic neurons since their last spiking time. We use the Galves-Löcherbach model to model this spike probability. When a neuron spikes, its membrane potential is reset to its resting potential and electrical signals are generated, modifying the membrane potential of all postsynaptic neurons. The relationship between a neuron and its presynaptic and postsynaptic neurons defines a weighted oriented graph. The objective of this work is studying, from a computation point of view, the performance of the estimation process of the connectivity graph from the observation of the neuronal activity of a finite set of neurons over a limited time interval, considering the Galves-Löcherbach model as underlying model.
Preparação de amostras sólidas empregando via úmida para determinações utilizando ICP OES
(Universidade Federal de São Carlos, 2022-09-16)
Gregori, Rafaela
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Pereira Filho, Edenir Rodrigues
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https://lattes.cnpq.br/3394181280355442
The present work aimed to evaluate the preparation of solid samples via wet in an open system with the aid of mineral acids for the quantification of metals in soils using the inductively coupled plasma optical emission spectrometry (ICP-OES) technique. In recent times, the disposal of solid waste, through industrial, agricultural, sewage irrigation, mining, etc., has been a serious problem for humanity due to soil contamination with contaminating elements, mercury, sulfur, silicon, cadmium, arsenic, rare among others. Causing damage not only to the environment, but also to human beings through the contamination of these metals. Thus, the preparation of samples of these soils is very important for the quantification of these metals present in the soils.
Avaliação do desgaste de massa de tamponamento via simulação termodinâmica e comparação com ensaio de corrosão dinâmico
(Universidade Federal de São Carlos, 2022-09-16)
Pinto, Victoria da Silva
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Luz, Ana Paula da
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https://lattes.cnpq.br/3470395641242374
The opening and closing of the tap hole during the production of pig iron in steel-making industries is crucial for the proper operation of the blast furnace and high production in the steel industry. The tap hole clay is the material used for this purpose and it acts : (i) closing the hole after the removal of liquids from the furnace, (ii) allowing the opening of the equipment, when it is necessary to drain the liquids again, and (iii) lining the inside of the blast furnace to protect the crucible. The hot face of this refractory mass has contact with slag and pig iron at temperatures above 1200°C, where the chemical composition of these liquids can lead to interactions that corrode/wear the ceramic, leaving the crucible wall exposed, which is one of the regions of the blast furnace that must be preserved due to its difficult maintenance. In this context, the understanding of the interactions that lead to the wear of the refractory mass is of great importance so that new formulations can be made. Thus, the objective of this work was to analyze and compare the behavior of a reference tap hole clay with others that contain the addition of MgO, TiO2 or Fe2O3 (in similar amounts) when in contact with a blast furnace slag. In this sense, thermodynamic simulations were performed via FactSage and corrosion tests were carried out in the laboratory, as the former considers that thermodynamic equilibrium was reached, and in practice, the contact of the material with the liquid is made for only a few hours, and this period may not be enough for all possible reactions to take place. Based on the studied compositions, the addition of TiO2 or Fe2O3 to the formulation resulted in similar behavior when compared to the reference composition, in both cases, the simulation and corrosion tests. On the other hand, the MgO incorporation to the mixture led to a greater number of calculation steps for the refractory stabilization in the simulation, and this trend was also observed in the experimental measurements, resulting in greater wearing of this tap role clay. It was also verified that the slag composition variation in the theoretical calculations was similar to the one found in the lab tests, indicating that, despite not quantifying the extent of wearing, thermodynamic simulation is valid for comparison and selection of formulations regarding their performance when in contact with reactive slag at high temperatures.