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Método de decomposição de Benders generalizado para seleção estocástica de portfólios.
No full textPrograma de Pós-Graduação em Engenharia de Produção. Departamento de Engenharia de Produção, Instituto de Ciências Exatas e Aplicadas, Universidade Federal de Ouro Preto.Este trabalho aborda o Problema de Seleção de Portfólios de Média-Variância. O problema
contém um conjunto de ativos financeiros, no qual cada ativo possui um peso associado a
sua escolha e um valor de retorno. O Retorno é obtido pela média dos retornos passados
dos ativos ponderados pelos respectivos pesos. Outro parâmetro considerado no problema é
o risco associado a cada ativo, obtido pela matriz variância-covariância. O objetivo é encon-
trar a melhor combinação dos ativos ponderados pelos pesos associados, buscando reduzir
o risco e aumentar o retorno. Para resolver o problema eficientemente, foram utilizados os
algoritmos Conjunto Ativo e o Método de Projeção em Caixa. Além disso, foi utilizada
uma técnica de pré-processamento para redução do tamanho da instância. Também, foi
proposta uma reformulação do problema, utilizando-se a versão estocástica do Método de
Decomposição de Benders Generalizado. Resultados computacionais mostraram a superio-
ridade do Método de Projeção em Caixa em relação ao Algoritmo do Conjunto Ativo.
Capaz de resolver instâncias com até 1.200 ativos, o Método de Projeção em Caixa superou
o Algoritmo do Conjunto Ativo em tempo de solução e número de iterações, sendo 83 vezes
mais rápido que o Algoritmo do Conjunto Ativo considerando o pior caso. Adicionalmente,
as soluções derivadas do Método de Projeção em Caixa foram confrontadas com aquelas
geradas pelo resolvedor de Programação Quadrática do Gurobi. Os resultados revelaram
que o maior desvio observado pelo Método de Projeção em Caixa foi da ordem de 10−9
.
Além disso, o código do Método de Projeção em Caixa, quando integrado ao Método de
Decomposição de Benders Generalizado, foi testado e comparado com o software Gurobi
considerando uma instância composta por 50 ativos e 500 cenários. O Método de Projeção
em Caixa apresentou tempos de solução inferiores em comparação com aqueles obtidos
pelo resolvedor de Programação Quadrática do Gurobi.This work addresses the Mean-Variance Portfolio Selection Problem. The problem contains
a set of financial assets, in which each asset has a weight associated with its choice and a
return value. The Return is obtained by averaging the past returns of assets weighted
by their respective weights. Another parameter considered in the problem is the risk
associated with each asset, obtained by the variance-covariance matrix. The objective
is to find the best combination of assets weighted by the associated weights, seeking
to reduce risk and increase return. To solve the problem efficiently, the Active Set
and Box Projection Method algorithms were used. Furthermore, a pre-processing
technique was used to reduce the instance size. Also, a reformulation of the problem
was proposed, using the stochastic version of the Generalized Benders Decomposition
Method. Computational results showed the superiority of the Box Projection Method
in relation to the Active Set Algorithm. Capable of solving instances with up to 1,200
assets, the Box Projection Method outperformed the Active Set Algorithm in solution time
and number of iterations, being 83 times faster than the Active Set Algorithm considering
the worst case. Additionally, the solutions derived from the Box Projection Method were
compared with those generated by the Gurobi Quadratic Programming solver. The results
revealed that the largest deviation observed by the Box Projection Method was of the
order of 10−9
. Furthermore, the Box Projection Method code, when integrated with the
Generalized Benders Decomposition Method, was tested and compared with the Gurobi
software considering an instance composed of 50 assets and 500 scenarios. The Box
Projection Method presented lower solution times compared to those obtained by Gurobi’s
Quadratic Programming solver
Evaluating testing strategies for resource related failures in mobile applications.
No full textMobile applications have been used for multiple purposes from entertainment to critical domains. As a consequence, the quality of mobile applications has become a crucial aspect, for instance, by promoting the use of testing as a quality assurance practice. The diversity of mobile platforms is pervaded by several resources related to communication capabilities, sensors, and user-controlled options. As a result, applications can present unexpected behaviors and resource interactions can introduce failures that manifest themselves in specific resource combinations. These failures can compromise the mobile application quality and harm the user experience. We evaluate the failure-detection capability and effectiveness of five sampling testing strategies (Random, One-Enabled, One-Disabled, Most-Enabled-Disabled, and Pairwise) in the context of resource related failures in 15 mobile applications. We focus on 14 common resources of the Android platform and analyze the resource interactions more likely to cause failures. Random had great percentages of failing test cases, followed by One-Enabled, Most-Enabled-Disabled, and Pairwise. We observe that One-Enabled and One-Disabled are the most effective testing strategies for six and four applications, respectively. Surprisingly, resource pairs have more influence on failures than other resource combinations, varying widely among the applications
Integrative transcriptome analysis of SARS‐CoV‐2 human‐infected cells combined with deep learning algorithms identifes two potential cellular targets for the treatment of coronavirus disease.
No full textSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) quickly spread worldwide, leading coronavirus disease
2019 (COVID-19) to hit pandemic level less than 4 months after the frst ofcial cases. Hence, the search for drugs and
vaccines that could prevent or treat infections by SARS-CoV-2 began, intending to reduce a possible collapse of health
systems. After 2 years, eforts to fnd therapies to treat COVID-19 continue. However, there is still much to be understood
about the virus’ pathology. Tools such as transcriptomics have been used to understand the impact of SARS-CoV-2 on dif-
ferent cells isolated from various tissues, leaving datasets in the databases that integrate genes and diferentially expressed
pathways during SARS-CoV-2 infection. After retrieving transcriptome datasets from diferent human cells infected with
SARS-CoV-2 available in the database, we performed an integrative analysis associated with deep learning algorithms to
determine diferentially expressed targets mainly after infection. The targets found represented a fructose transporter (GLUT5)
and a component of proteasome 26s. These targets were then molecularly modeled, followed by molecular docking that
identifed potential inhibitors for both structures. Once the inhibition of structures that have the expression increased by the
virus can represent a strategy for reducing the viral replication by selecting infected cells, associating these bioinformatics
tools, therefore, can be helpful in the screening of molecules being tested for new uses, saving fnancial resources, time, and
making a personalized screening for each infectious disease
Thermal and colorimetric parameter evaluation of thermally aged materials : a study of diglycidyl ether of bisphenol A/triethylenetetramine system and fique fabric-reinforced epoxy composites.
No full textThe main modifications of thermal and colorimetric parameters after thermal aging of DGEBA/TETA system (plain epoxy) and fique-fiber woven fabric-reinforced epoxy composites are described. As a preliminary study, thermal analysis was carried out on epoxy matrix composites reinforced with 15, 30, 40 and 50% fique-fiber woven fabric. After this previous analysis, the 40% composite was chosen to be thermally aged, at 170 °C. Three exposure times were considered, namely, 0, 72, 120 and 240 h. Samples were studied by thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermomechanical analysis (TMA) and colorimetry analysis. Significant color changes were observed after thermal aging combined with oxidation. It was also found that the thermal behavior of the plain epoxy showed greater resistance after thermal exposure. By contrast, the composites were more sensitive to temperature variations as a result of thermal stresses induced between fique fibers and the epoxy matrix
Colorimetric nanosensor for the determination of glyphosate herbicide in aqueous solutions.
No full textDetection of pesticides depends on complex, time-consuming, and costly techniques
performed only in some regions of Brazil. Thus, this study aimed to develop a sensitive, portable, easy-
to-handle, and fast nanosensor to determine the presence of glyphosate in aqueous solutions. The
Co(OH)2 nanostructure was synthesized, and the kinetic study of the interaction with pesticide
glyphosate-based was performed. The Co(OH)2 nanostructures had a fast and effective interaction,
confirmed by UV-Visible spectroscopy. Through experimental planning, the process for obtaining
nanostructures has been optimized, and the nanostructures obtained were in a size range of 434.2 nm
with a hexagonal nanoplate structure. The lower limit of color-based glyphosate detection was 0.178
g
.L
-1
. It was possible to identify the herbicide in the water of the tomato and sugar cane rinse by the
change of the watercolor into pink. Although the samples showed low absorbance, the color change was
noticeable to the naked eye. Therefore, to synthesize a structure that allows identifying glyphosate in a
colorimetric way
Modelo de simulação para sistemas produtivos integrado entre mina, usina e expedição.
No full textPrograma de Pós-Graduação em Engenharia Mineral. Departamento de Engenharia de Minas, Escola de Minas, Universidade Federal de Ouro Preto.As cadeias produtivas industriais, entre elas a mineração, exigem cada vez mais
eficiência e integração. Neste sentido, este trabalho propõe o uso da simulação por eventos
discretos como ferramenta útil ao planejamento de produção e tomada de decisão em uma
mineração, considerando as interferências entre mina, usina de tratamento de minérios e
expedição, com enfoque em um horizonte de curto prazo (trimestral). O estudo de caso usou
como base um empreendimento com sistema de lavra rígido e integrado por correias, da
mina à expedição, com poucas possibilidades de estoque de material ao longo do circuito
produtivo para possíveis misturas e ajustes da qualidade do material. Foram simulados
cenários os quais propõem soluções para aumento de produção por meio de mudanças nas
configurações técnicas do sistema produtivo e não por meio da identificação de melhores
frentes de lavra na mina, uma vez que a lavra rígida impõe dificuldades a este tipo de
solução. Este trabalho também traz, como um dos fatores geradores de paradas de produção,
o tipo de material que está sendo manuseado. Isto é relevante, pois cada tipo de material
pode causar um impacto operacional e/ou mecânico, a depender das proporções destes
materiais em dado momento do modelo simulado. Devem ser identificados e impactos
devem ser mitigados, para os momentos em que ocorrerá a combinação da lavra de
materiais com comportamento coesivo, aumentando as possibilidades de entupimentos em
dispositivos de transferência. Também devem ser identificados os momentos que ocorrerão
a combinação da lavra de materiais com maior resistência mecânica e, portanto, maior
probabilidade de causar danos às correias e materiais de desgaste. Na prática atual, rotinas
de planejamento de lavra e programação de produção de curto prazo, usualmente,
consideram como premissas poucos dados determinísticos, sem levar em conta a dinâmica
trazida pela combinação destes possíveis eventos em cada instante do processo produtivo.
Quanto às simulações realizadas no software Flexsim, algumas premissas probabilísticas
do sistema produtivo foram obtidas de forma empírica e, um refinamento destes dados, por
meio de estudos estatísticos obtidos de sistemas de apontamentos e despacho, poderá ser
considerado como proposta para trabalhos futuros.Since industrial production chains demand more and more efficiency and integration,
this work proposes the use of discrete event simulation as a useful tool for production
planning and decision making in mining, considering the interferences between the mine,
plant and dispatch, focusing on a short-term horizon (quarterly). The case study used as
mine data an enterprise with a rigid mining system integrated by belts, from the mine to the
train loading point, with few possibilities of material stock along the production circuit for
possible blending to adjust the quality. Scenarios were simulated which propose solutions
to increase production through changes in the technical configurations of the production
system, not through the identification of better mining fronts in the mine, once rigid mining
difficulties this type of solution. This work also brings as one of the factors that generate
production stoppages the type of material being produced. It is relevant, as each type of
material can cause an operational and/or mechanical impact, depending on the proportions
of these materials at a given moment in the simulated model. They must be identified, and
impacts must be mitigated, for the moments that the combination of materials with cohesive
behavior will occur, increasing the possibilities of clogging in transfer structures. The
moments that materials with greater mechanical resistance are mined, and therefore more
likely to cause damage to the belts and wear materials, must also be identified. Usually,
mine planning and short-term production scheduling routines usually only consider few
deterministic data as assumptions, without considering the dynamics about the combination
of these possible events at each instant of the production process. About the simulations
carried out in the Flexsim software, some probabilistic assumptions of the production
system were empirically obtained, and a refinement of these data, through statistical studies
obtained from note and dispatch systems, may be considered as a proposal for future work
Otimização de técnicas geoelétricas para caracterização estrutural e hídrica de maciços com porosidade fissural e cárstica.
No full textPrograma de Pós-Graduação em Geotecnia. Núcleo de Geotecnia, Escola de Minas, Universidade Federal de Ouro Preto.Identificar e caracterizar descontinuidades geológicas é relevante para o entendimento e
solução de diversos problemas geotécnicos e hidrogeológicos, especialmente em maciços com
porosidade fissural e cárstica. Na região do Quadrilátero Ferrífero, predominam meios com
porosidade fissural, mas meios com porosidade cárstica são também relevantes, especialmente
em formações ferruginosas. A Eletrorresistividade (Electrical Resistivity – ER) e o Potencial
Espontâneo (Spontaneous Potential – SP) são métodos geofísicos de baixo custo que têm sido
utilizados para este fim, mas a grande variabilidade das condições geológicas nestes meios
dificulta a comparação das diversas técnicas e arranjos de aquisição de dados. Uma alternativa
ainda pouco empregada para superar este problema consiste na aplicação destes métodos em
modelos físicos reduzidos, onde as condições internas e de fronteira são conhecidas, em
associação com modelagens geoelétricas numéricas, diretas ou inversas. Nesta pesquisa,
objetivou-se caracterizar os padrões de descontinuidades e as condições de fluxo em modelos
físicos que replicam modelos conceituais comuns nesta região, como os maciços fraturados
recortados por duas ou três famílias de fraturas com variadas atitudes e espaçamentos, e de
maciço em unidades ferríferas com cavidade com diversas tipologias e orientações de
condutos e salões. Inicialmente, foram feitas modelagens geoelétricas numéricas diretas para
estes modelos conceituais para prever os resultados esperados dos levantamentos geoelétricos
e, desta forma, melhor dimensionar os modelos físicos reduzidos. A comparação de diversos
tipos de arranjos e técnicas de levantamento possibilitaram otimizar a aplicação destes
métodos na caracterização das condições estruturais e hídricas nestes maciços. Os resultados
revelaram que o arranjo Gradiente é muito indicado para mapear fraturas verticais, inclusive
para discernir fraturas individuais de um mesmo conjunto, secundado pelos arranjos azimutais
Dipolo-Dipolo Equatorial e Quadrático. Estes últimos apresentam alta acurácia para a
estimativa da porosidade fissural. Foram determinadas relações ótimas entre o espaçamento
intereletrodo ideal para a identificação de descontinuidades com um dado espaçamento. O
Dipolo-Dipolo mostrou-se adequado para a identificação de descontinuidades, quando se
utilizaram vários espaçamentos intereletrodo nas linhas, mas rigorosamente comparado com o
Gradiente, este foi o melhor. O Potencial Espontâneo mostrou-se adequado para identificar
sentido de fluxo e rebaixamento de aquífero em meios com porosidade fissural. A umidade no
entorno de cavidades ferríferas pode atenuar o sinal elétrico ou até mesmo mascarar o alto
resistivo de condutos e salões preenchidos com ar.Identifying and characterizing geological discontinuities is relevant for understanding and
solving several geotechnical and hydrogeological problems, especially in rock masses with
fissure and karst porosity. In the Quadrilátero Ferrífero region, media with fissure porosity
predominate, but media with karstic porosity are also relevant, especially in ferruginous
formations. Electrical Resistivity (ER) and Spontaneous Potential (SP) are low-cost
geophysical methods that have been used for this purpose, but the great variability of
geological conditions in these media makes it difficult to compare different techniques and
data acquisition arrays. An alternative still little used to overcome this problem consists of
applying these methods in reduced physical models, where the internal and boundary
conditions are known, in association with numerical, direct, or inverse geoelectric modeling.
In this research, the objective was to characterize the patterns of discontinuities and the flow
conditions in physical models that replicate common conceptual models in this region, such as
the fractured masses cut by two or three patterns of fracturing with varied attitudes and
spacing, and the mass in ferruginous units with cavity with different types and orientations of
conduits and saloons. Initially, direct numerical modeling was done for these conceptual
models to predict the expected results of geoelectric surveys and, in this way, better
dimension the reduced physical models. The comparison of different types of arrays and
surveying techniques made it possible to optimize the application of these methods in the
characterization of structural and water conditions in these masses. The results revealed that
the Gradient array is very suitable for mapping vertical fractures, including for discerning
individual fractures of the same set, followed by the Equatorial Dipole-Dipole and Quadratic
azimuthal arrays. The latter have high accuracy for estimating fissure porosity. Optimal
relationships were determined between the ideal interelectrode spacing for the identification
of discontinuities with a certain spacing. The Dipole-Dipole array proved to be adequate for
the identification of discontinuities when several interelectrode spacings were used in the
survey lines, but rigorously compared with the Gradient, this was better. The Spontaneous
Potential proved to be adequate to identify flow direction and aquifer drawdown in media
with fissure porosity. Moisture around iron caves can attenuate the electrical signal or even
mask the high resistivity of gaps filled with air
The Horse Race Workshop adjusted to the remote format : teachers and undergraduates’ weighing.
No full textOne of the first pandemic outcomes in Brazil was academic calendar suspension. Teachers
and undergraduates saw themselves in need of thinking about alternatives to access and
share the valued historically and socially accumulated knowledge. Once stopped by this
situation, and by being aware of the existing demand by the Mathematics field for the
production of knowledge related to Probability teaching, we adjusted and provided the
workshop in remote format. It was made available on a communication platform at a time
when such a format was not yet popular. We were guided by the following enquiry: how
could participation in the workshop, and made possible by the cyberspace, echo on a group
of teachers and undergraduates? Thus, the herein reported investigation is methodologically
based on assumptions of a qualitative research aimed at analyzing the material resulting from
audio and video recordings, based on participant speeches’ transcriptions, as well as on
answers in the workshop evaluation form. The analysis was theoretically supported by
concepts found in the Historical-Cultural tradition. It has shown that participation echoed
differently on distinct participants - this finding shows lack of consensus among them about
whether is feasible, or not, if one has in mind Mathematics remote classroom. It has also
shown that such differences are related to non-appropriation of some artifacts by several
participants. Nevertheless, we have noticed that participants started seeing possibilities of
actions right at the beginning of the remote classes, and it has pointed towards the fact that
this appropriation could actually come true.En Brasil, uno de los desarrollos iniciales de la pandemia de COVID-19 fue la suspensión del
calendario académico. En este contexto, docentes y estudiantes de pregrado se vieron
enfrentados a la necesidad de pensar alternativas para acceder y compartir el conocimiento
escolar. Impulsados por esta situación, hicimos adaptaciones y ofrecimos el curso corto, en
formato remoto, a través de una plataforma de comunicación en un momento en que aún no
se había popularizado. Teniendo esta experiencia como objeto de reflexión, y haciendo uso
del diálogo sobre tecnologías y ciberespacio, elaboramos este trabajo, guiados por la
siguiente pregunta: ¿cómo se adapta la participación en el minicurso al formato a distancia,
e hizo posible por el ciberespacio, reverberar en un grupo de profesores y estudiantes? Así,
llevamos a cabo una investigación cualitativa cuyo material empírico consistió en la grabación
de audio y video del minicurso, las transcripciones de los discursos de los participantes, así
como las respuestas al formulario de evaluación. El análisis, anclado en la tradición Histórico-
Cultural, reveló que la participación repercutió de diferente manera en los participantes,
indicando que no hubo consenso entre ellos sobre si el minicurso era viable frente a la Aula a
distancia de Matemáticas. También mostró que tales diferencias estaban relacionadas con la
no apropiación, por parte de la mayoría de los profesores y estudiantes universitarios, de
algunos artefactos presentados. Además, notamos que los participantes comenzaron a
vislumbrar posibilidades de acciones, en un momento inicial del contexto remoto, señalando
direcciones para que esa apropiación pudiera ocurrir
Um curso de formação continuada para professores de ciências/química : saberes da educação de surdos.
No full textPrograma de Pós-Graduação em Ensino de Ciências, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto.Existem diversas problemáticas que ainda permeiam a Educação de Surdos. Para minimizá-las, são necessárias ações que visem uma maior inclusão desses estudantes. Sendo assim, o presente trabalho busca, por meio da criação e oferta de um curso de formação continuada na modalidade on-line sobre Educação de Surdos, responder o seguinte problema de pesquisa: De que forma um curso de formação continuada pode impactar na construção de conhecimentos dos docentes de Ciências/Química sobre a Educação de Surdos? A pesquisa, que tem natureza qualitativa de caráter exploratório em um formato de estudo de caso, foi desenvolvida em quatro etapas: i) criação de um curso para professores da educação básica; ii) aplicação do curso; iii) entrevista semiestruturada com participantes do curso; iv) análise de dados. Os resultados da análise do questionário inicial apontam que os professores, em sua maioria, estão no início da carreira docente e possuem algum conhecimento sobre a Educação de Surdos. Na análise das atividades realizadas no curso, foi possível perceber que os cursistas demonstraram refletir sobre aspectos relevantes da Educação de Surdos, como, por exemplo, a importância do visual e o processo de inclusão dos estudantes. Por fim, nas entrevistas, observou-se que os professores consideraram o curso relevante para o aprimoramento da sua prática docente, destacando a importância do curso, ao apresentar propostas de uso de ferramentas pedagógicas, ser uma atualização do conhecimento e promover a compreensão das características e identidade da comunidade Surda. A partir disso, consideraram o curso um grande aliado na promoção da inclusão educacional de Surdos. Sendo assim, conclui-se que o curso cumpriu com os seus objetivos e tem potencialidades para contribuir para a formação continuada de professores de Química, Física e Biologia ao discutir aspectos relevantes sobre a temática, como, por exemplo, a importância dos aspectos visuais para os Surdos, cultura e identidade Surda e, ainda, sugestão de ferramentas pedagógicas.There are several problems that still permeate the Education of the Deaf. In order to minimize them, actions are needed aimed at greater inclusion of these students. Therefore, the present work seeks, through the creation and offer of an online continuing education course on Education for the Deaf, to respond to the following research problem: How can a continuing education course impact the construction of knowledge of Science/Chemistry teachers about Education for the Deaf? The research, which has an exploratory qualitative nature, in a case study format, was developed in four stages: i) creation of a course for basic education teachers; ii) cursor application; iii) semi-structured interview with course participants; iv) data analysis. Preliminary results of the analysis of the initial advisor indicate that most teachers are at the beginning of their teaching career and have some knowledge about Deaf Education. In the analysis of the activities carried out in the course, it was possible to perceive that the course participants felt that they were reflecting on relevant aspects of education for the Deaf, such as, for example, the importance of visuals and the process of inclusion of students. Finally, in the interviews, it was observed that the teachers consider the course relevant for improving their teaching practice, highlighting the importance of the course in presenting proposals for the use of pedagogical tools, being an update of knowledge and promoting understanding of the characteristics and deaf community identity. From this, consider the course a great ally in promoting the educational inclusion of the Deaf. Therefore, it is concluded that the course fulfilled its objectives and has the potential to contribute to the continuing education of Chemistry, Physics and Biology teachers, by discussing relevant aspects of the subject, such as, for example, the importance of visual aspects for the Deaf, Deaf culture and identity, and also a suggestion of pedagogical tools
On the convergence of the fractional relativistic Schrodinger operator.
No full textIn this paper, we deal with the convergence of the fractional relativistic Schrodinger operator (− + m2) s as s → 1−. Intuitively, this operator converges to (− + m2) but the proof of this result is not so simple and it is based on a careful analysis of the involved modified Bessel function Kν . The convergence of the operator makes natural the following question: do the solutions of the problem (− + m2) s w = f (w) in RN converge, in a suitable sense, to a solution u of the problem (− + m2)v = f (v) in RN as s → 1−? We will show that the answer is affirmative under reasonable hypotheses. The proof of the convergence of solutions is obtained by combining an immersion result for Bessel potential spaces with the uniform convergence on compact sets. To the best of our knowledge, the analogous result for the fractional Laplacian operator (−)s has not been established yet