Artigos - Matemática - FC

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https://hdl.handle.net/11449/8537

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Mathematical Model with Pressure Constraints to Minimize Electric Energy Costs in the Operation of Hydraulic Pumps
(2023-03-01) Miquelin, Leticia Maria [UNESP]; Santos, Maristela Oliveira Dos; Mansano Furlan, Marcos; Soler, Edilaine Martins [UNESP]; Universidade Estadual Paulista (UNESP); Universidade de São Paulo (USP); Universidade Federal da Grande Dourados (UFGD)
Water supply systems are responsible for providing quality water to the population in sufficient quantity. As sanitation companies are major energy consumers of electrical power, they have a contract of power in which the cost of electricity varies according to the period of the day. Thus, for these companies, at peak times the price of electricity is much higher. Most of the expenditure on electricity in water supply systems is due to hydraulic pumps, which are activated when the level of the tanks reaches the minimum level and remain on until the maximum levels are reached, without taking into account the time where this operation is performed. This work proposes a mathematical model for the optimization of electricity costs in water supply systems through the planning of the operation of hydraulic pumps. Numerical tests were performed through the implementation of the proposed model in GAMS software and solved by the CPLEX optimization package for different demand scenarios, in order to validate the proposed model. A model that simulates the operation performed in the practice of water supply systems is also presented, and its results are compared to the proposed optimization model. The obtained results proof of the efficiency of hydraulic pumps operation planning provided by the proposed model in relation to the operation performed in practice in water supply systems.
Use of Natural Latex as a Biomaterial for the Treatment of Diabetic Foot - a New Approach to Treating Symptoms of Diabetes Mellitus
(Intechopen, 2015-01-01) Rodrigues Fleury Rosa, Suelia de Siqueira; Reis, Maria do Carmo; Fleury Rosa, Mario Fabricio; Colon, Diego; Reis, Celia Aparecida dos [UNESP]; Balthazar, Jose Manoel [UNESP]; Claborn, D.; Universidade de Brasília (UnB); Universidade de São Paulo (USP); Universidade Estadual Paulista (UNESP)
Influence of structural disorder on the photocatalytic properties of ZnS nanocrystals prepared by the one-pot solvothermal approach
(2022-01-01) Benatto, Victoria Gabriela; Da Silva Lopes Fabris, Guilherme [UNESP]; Sambrano, Julio Ricardo [UNESP]; Taft, Carlton Anthony; De Almeida La Porta, Felipe; Laboratory of Nanotechnology and Computational Chemistry; Federal University of Rio Grande do Norte; Universidade Estadual Paulista (UNESP); Brazilian Center of Physical Research; Universidade Estadual de Londrina (UEL)
This study focuses on the impact of the sulfur vacancies on the photocatalytic response of the ZnS nanocrystals synthesized by solvothermal method varying the concentration of zinc acetate/thiourea precursors. XRD patterns show that these samples have a hexagonal structure with different degrees of crystallinity, varying the crystallite size from 2.48 to 2.85 nm. The UV-Vis data reveals an absorption peak (at about 320 nm) characteristic of ZnS nanocrystals. As a result, a decrease in the bandgap value of these materials was observed from 3.78 to 3.62 eV. In principle, a comparison of these results and theoretical calculations reveals the formation of intermediate levels inside the bandgap due to structural polarization. These findings also corroborate the zeta potential measured for these samples, evidenced by an increase of positive charge of ZnS surfaces. Also, the low Miller-index surfaces, such as (101-0), (112-0) and (0001), were investigated by periodic density functional theory calculations, in nice agreement with the experimental data. A photocatalysis mechanism was investigated and confirmed the formation of reactive oxygen species.
Enhancing the mechanical properties and providing bioactive potential for graphene oxide/montmorillonite hybrid dental resin composites
(2022-12-01) Velo, Marilia Mattar de Amôedo Campos; Filho, Francisco Gilmário Nunes; de Lima Nascimento, Tatiana Rita; Obeid, Alyssa Teixeira; Castellano, Lúcio Cançado; Costa, Reginaldo Mendonça; Brondino, Nair Cristina Margarido [UNESP]; Fonseca, Maria Gardennia; Silikas, Nikolaos; Mondelli, Rafael Francisco Lia; Universidade de São Paulo (USP); Federal University of Paraiba; Universidade Federal da Paraíba (UFPB); Universidade Estadual Paulista (UNESP); The University of Manchester
This in vitro study synthetized hybrid composite nanoparticles of graphene oxide (GO) and montmorillonite MMt (GO-MMt) by ultrasound treatments. Samples were characterized by X-ray diffraction, FT-Raman, FTIR, TEM and SEM. The effect of their incorporation (0.3% and 0.5%) on the mechanical properties in a resin-based composite (RBC) and their bioactivity potential were evaluated. The specimens were characterized by evaluating their 3-point flexural strength (n = 6), modulus of elasticity (n = 6), degree of conversion (n = 6), microhardness (n = 6), contact angle (n = 3) and SEM analysis (n = 3). In vitro test in SBF were conducted in the RBCs modified by the hybrid. Overall, the synthetized hybrid composite demonstrated that GO was intercalated with MMt, showing a more stable compound. ANOVA and Tukey test showed that RBC + 0.3% GO-MMt demonstrated superior values of flexural strength, followed by RBC + 0.5% GO-MMt (p < 0.05) and both materials showed higher values of microhardness. All groups presented a contact angle below 90°, characterizing hydrophilic materials. RBCs modified by the hybrid showed Ca and P deposition after 14 days in SBF. In conclusion, RBCs composed by the hybrid showed promising results in terms of mechanical properties and bioactive potential, extending the application of GO in dental materials.
Emptiness in Tragic Times: some remarks on today´s Brazilian public policies
(2022-01-01) Garnica, Antonio Vicente Marafioti [UNESP]; Universidade Estadual Paulista (UNESP)
This paper has a hybrid structure and is, at the same time, an academic essay, a manifesto and a summary of articles published in the mainstreammedia. It was composed, mainly, from journalistic sources, and has as its theme the current Brazilian public policies. To argue about the absence of these public policies today, the article presents a summary of situations that characterize the Bolsonaro Administration and ends with some brief remarks on public policies in Mathematics Education, particularly those related to Distance Education.
Performance and stability of femtosecond laser-irradiated Fe2O3 materials as photocatalysts for methylene blue dye discoloration
(2022-01-01) Souza, Josiane Carneiro; Martins, Tiago Almeida; de Oliveira, Regiane Cristina [UNESP]; Sambrano, Julio Ricardo [UNESP]; Mendonça, Cleber Renato; de Boni, Leonardo; Leite, Edson Roberto; Longo, Elson; Universidade Federal de São Carlos (UFSCar); Universidade Estadual Paulista (UNESP); Universidade de São Paulo (USP)
The disposal of substances pollutant, such as methylene blue dye (MB), into wastewater, arouses the interest of technologies to remove these pollutants. The discoloration of MB by photocatalysis and using femtosecond laser-irradiated Fe2O3 materials as photocatalysts proved to be a promising way to treat this pollutant. Here, Fe2O3 obtained by the conventional hydrothermal process and heat-treatment, subsequently femtosecond laser-irradiated treatment. Materials obtained with a mixture of irradiated α-Fe2O3 and ε-Fe2O3 phases revealed lower crystallinity than irradiated α-Fe2O3 samples. The irradiation treatment and the increase in crystallinity were crucial to improve the performance of α-Fe2O3 irradiated sample in the discoloration of MB, which reached 90% in 75 min of dye solution exposure under UV irradiation. The irradiation treatment proved to allow greater exposure of the particle surfaces, which coalesced and presented a greater distribution of medium size, indicating a more heterogeneous morphology in the irradiated samples. As a result, there was an increase in active sites due to the density of defects generated, which facilitated the dye degradation process.
Optimization-Based Models for Estimating Residual Demand Curves for a Price-Maker Company
(2022-01-01) Cabana, Tiago G.; Baptista, Edmea C.; Soler, Edilaine M.; Martins, Andre C. P.; Balbo, Antonio R.; Nepomuceno, Leonardo; Universidade Estadual Paulista (UNESP)
The Residual Demand Curve (RDC) aims to estimate the day-ahead market clearing prices given the quotas scheduled for a price-maker generation company in the market. Traditionally, this curve has been obtained by the difference between the inverse functions of aggregated demand and aggregated supply. An important drawback of such approach is that constraints related to complex-bid markets cannot be directly represented in the RDC. In this paper we interpret the traditional RDC as an optimization model and propose Optimization-Based Residual Demand (OBRD) models which represent a series of market clearing procedures where the residual demand is progressively increased. Differently from traditional methods, the proposed approach allows for explicit representation of complex-bid markets. We show that under certain conditions the RDC obtained by the proposed OBRD model is equivalent to that provided by traditional methods. We also propose a methodology for comparing the quality of different RDCs in what regards their ability to predict market clearing prices and the company's profits. Results show that the RDCs obtained by the OBRD model are significantly more accurate than those obtained by traditional approaches for complex-bid markets.
Effect of thickness on shrinkage stress and bottom-to-top hardness ratio of conventional and bulk-fill composites
(2021-12-01) Santin, Daniella Cristo; Velo, Marilia Mattar de Amoêdo Campos; Camim, Francielly da Silva; Brondino, Nair Cristina Margarido [UNESP]; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia; Universidade de São Paulo (USP); Universidade Estadual Paulista (UNESP)
This study evaluated the effect of the material thickness on shrinkage stress and bottom-to-top hardness ratio of conventional and bulk-fill composites. Six commercial composites were selected based on their different technologies: Two conventional (C1, C2), two high-viscosity bulk-fill (HVB1, HVB2), and two low-viscosity bulk-fill (LVB1, LVB2). Shrinkage stress was analyzed for five specimens with 2 mm thickness (C-factor 0.75 and volume 24 mm3) and five specimens with 4 mm thickness (C-factor 0.375 and volume 48 mm3) for 300 s in a universal testing machine. Bottom-to-top hardness ratio values were obtained from Knoop microhardness measurements in specimens with 2- and 4-mm thickness (n = 5). Thickness increase resulted in significantly higher shrinkage stress for all materials with the exception of HVB2 and LVB1. C1, C2, HVB2, and LVB1 showed lower bottom-to-top hardness ratios at 4 mm than at 2 mm. Only LVB2 presented a bottom-to-top hardness ratio lower than 80% at 2 mm, while HVB1 surpassed this threshold at 4 mm of depth. The results suggest that the increase of composite thickness affected the shrinkage stress values. Also, thickness increase resulted in lower bottom-to-top hardness ratio. HVB1 showed better behavior than other bulk-fill materials, with low stress and adequate bottom-to-top hardness ratio at 4 mm thickness.
Método Híbrido de Pontos Interiores com Enxame de Partículas para Resolução do Problema de Fluxo de Potência Ótimo Reativo com Variáveis Discretas
(2021-08-15) Pavan, Rafael [UNESP]; Soler, Edilaine Martins [UNESP]; Universidade Estadual Paulista (UNESP)
History of Mathematics Education in Brazil: an overview of secondary education
(2021-08-01) Gomes, Maria Laura Magalhães; Garnica, Antonio Vicente Marafioti [UNESP]; Universidade Federal de Minas Gerais (UFMG); Universidade Estadual Paulista (UNESP)
The field of the history of mathematics education, inscribed in the field of research on mathematics education in Brazil, has been developed as a result of the work of many groups of researchers, dedicated to varied themes under the light of various theoretical and methodological approaches. While it is impossible to describe in detail such studies in a single article, the objective of this text is to offer an overview of research results on a specific topic – mathematics in secondary education and training of teachers to teach at this level, over the years. The current situation of the country regarding education in general is related to the past and different Brazilian political periods: Colony, Empire and Republic. We will succinctly examine the beginnings of Brazilian basic school education before the Republic, seeking to highlight characteristics of secondary school studies, especially regarding the teaching of mathematics. Then, we will focus on the same themes during the period after the establishment of the Republican regime. Finally, we will discuss the historical trajectory of the training mathematics teachers who work on secondary education in the country.
Suppression of Anderson localization of light in one-dimensional disordered photonic superlattices
(2012-05-07) Reyes-Gómez, E.; Bruno-Alfonso, A. [UNESP]; Cavalcanti, S. B.; Oliveira, L. E.; Universidad de Antioquia; Universidade Estadual Paulista (UNESP); Universidade Federal de Alagoas; Universidade Estadual de Campinas (UNICAMP)
The localization properties of electromagnetic modes in one-dimensional disordered photonic superlattices are theoretically studied. The multilayered system is considered to be composed of alternating stacks of two different random-thickness slabs, characterized by nondispersive and/or frequency-dependent electric permittivities and magnetic permeabilities. Results for the localization length are evaluated by using an analytical model for weakly disordered systems as well as its general definition through the transmissivity properties of the heterostructure. Good agreement between both results is observed only for small amplitudes of disorder. The critical frequencies at which the localization length diverges are correctly predicted in the whole frequency spectrum by the analytical model and confirmed via the corresponding numerical calculations. The λ2 dependence of the localization length, previously observed in disordered heterostructures made of material of positive refractive indexes, are confirmed in the present work. In addition, new λ4 and λ -4 dependencies of the localization length in positive-negative disordered photonic superlattices are obtained, under certain specific conditions, in the long and short wavelength limits, respectively. The asymptotic behavior of the localization length in these limits is essentially determined by the particular frequency dispersion that characterizes the metamaterial used in the left-handed layers. When the effects of absorption are considered, then a divergence of the localization length is still observed, under some conditions, in the short wavelength limit. © 2012 American Physical Society.
Anderson localization and Brewster anomalies in photonic disordered quasiperiodic lattices
(2011-09-21) Reyes-Gómez, E.; Bruno-Alfonso, A. [UNESP]; Cavalcanti, S. B.; Oliveira, L. E.; Universidad de Antioquia; Universidade Estadual Paulista (UNESP); Universidade Federal de Alagoas; Universidade Estadual de Campinas (UNICAMP)
A comprehensive study of the properties of light propagation through one-dimensional photonic disordered quasiperiodic superlattices, composed of alternating layers with random thicknesses of air and a dispersive metamaterial, is theoretically performed. The superlattices consist of the successive stacking of N quasiperiodic Fibonacci or Thue-Morse heterostructures. The width of the slabs in the photonic superlattice may randomly fluctuate around its mean value, which introduces a structural disorder into the system. It is assumed that the left-handed layers have a Drude-type dispersive response for both the dielectric permittivity and magnetic permeability, and Maxwell's equations are solved for oblique incidence by using the transfer-matrix formalism. The influence of both quasiperiodicity and structural disorder on the localization length and Brewster anomalies are thoroughly discussed. © 2011 American Physical Society.
Calculation of magnetodonor states in InP and polaron effects
(2009-05-20) Bruno-Alfonso, Alexys [UNESP]; Hai, Guo-Qiang; Universidade Estadual Paulista (UNESP); Universidade de São Paulo (USP)
Far-infrared transitions in polar semiconductors are known to be affected by the presence of shallow donor impurities, external magnetic fields and the electron-LO-phonon interaction. We calculate the magnetodonor states in indium phosphide by a diagonalization procedure, and introduce the electron-phonon interaction by the Fröhlich term. The main effects of this perturbation are calculated by a multi-level version of the Wigner-Brillouin theory. We determine the transition energies, from the ground state to excited states, and find good qualitative agreement with recently reported absorption-spectroscopy measurements in the 100-800 cm-1 range, with applied magnetic fields up to 30 T. Our calculations suggest that experimental peak splittings in the 400-450 cm-1 range are due to the electron-phonon interaction. © 2009 World Scientific Publishing Company.
Band edge states of the n =0 gap of Fibonacci photonic lattices
(2008-09-04) Bruno-Alfonso, A. [UNESP]; Reyes-Gómez, E.; Cavalcanti, S. B.; Oliveira, L. E.; Universidade Estadual Paulista (UNESP); Universidad de Antioquia; Universidade Federal de Alagoas; Inmetro; Universidade Estadual de Campinas (UNICAMP)
The stationary and normally incident electromagnetic modes in Fibonacci lattices with generating layers of positive and negative indices of refraction are calculated by a transfer-matrix technique. It is shown that the condition for constructive interference of reflected waves is fulfilled when the ratio of optical paths in positive and negative media are given by the golden ratio. Furthermore, in the long-wavelength limit, it is demonstrated that the edges of the n =0 gap are the frequencies satisfying the conditions =0 and μ =0. © 2008 The American Physical Society.
Pb1-x Cax TiO3 solid solution (x=0.0, 0.25, 0.50, and 0.75): A theoretical and experimental approach
(2007-04-25) De Lázaro, Sérgio Ricardo; De Lucena, Poty Rodrigues; Sambrano, Júlio Ricardo [UNESP]; Pizani, Paulo Sérgio; Beltrán, Armando; Varela, José Arana [UNESP]; Longo, Elson [UNESP]; Universidade Federal de São Carlos (UFSCar); Universidade Federal da Bahia (UFBA); Universidade Estadual Paulista (UNESP); Universitat Jaume I; Laboratório Interdisciplinar de Eletroquímica e Cerâmica
In this paper we report an experimental and theoretical study based on a periodic density functional investigation into selected compositions of Pb1-x Cax TiO3 (x=0.0, 0.25, 0.50, and 0.75). Based on our findings, we propose that the pseudocubic structure of these perovskites presents a long-range tendency for cubic symmetry, while the short-range displacements bring the solid solution to a tetragonal symmetry. The results are discussed in terms of x-ray diffraction, structural optimized parameters, Raman spectroscopy, band structure, density of states, Mulliken charge, and overlap population. © 2007 The American Physical Society.
On a control of a non-ideal mono-rail system with periodics coefficients
(2005-12-01) Peruzzi, N. J.; Balthazar, J. M.; Pontes, B. R.; Universidade de São Paulo (USP); Universidade Estadual de Campinas (UNICAMP)
In this work, the problem in the loads transport (in platforms or suspended by cables) it is considered. The system in subject is composed for mono-rail system and was modeled through the system: inverted pendulum, car and motor and the movement equations were obtained through the Lagrange equations. In the model, was considered the interaction among of the motor and system dynamics for several potencies motor, that is, the case studied is denominated a non-ideal periodic problem. The non-ideal periodic problem dynamics was analyzed, qualitatively, through the comparison of the stability diagrams, numerically obtained, for several motor torque constants. Furthermore, one was made it analyzes quantitative of the problem through the analysis of the Floquet multipliers. Finally, the non-ideal problem was controlled. The method that was used for analysis and control of non-ideal periodic systems is based on the Chebyshev polynomial expansion, in the Picard iterative method and in the Lyapunov-Floquet transformation (L-F transformation). This method was presented recently in [3-9]. Copyright © 2005 by ASME.
Thirteen-band tight-binding model for the MoS2 monolayer
(2021-01-01) Meneghetti, Luiz Antonio [UNESP]; Bruno-Alfonso, Alexys [UNESP]; Universidade Estadual Paulista (UNESP)
A tight-binding model is fitted to density-functional calculations of the electronic structure of the MoS2 monolayer. The model involves 13 atomic orbitals per unit cell: the 4d orbitals of the molybdenum atom plus the 3s and 3p orbitals of each sulfur atom. The hopping and overlap couplings of each atom with its first nearest neighbors in each crystalline sublattice are considered. Different values are allowed for the intraplane and interplane S-S hopping integrals. A closed-form expression is given for the effective-mass tensor at stationary points. The isotropy of the valence and conduction bands near the edges of the fundamental gap is proven. The role played by the orbital overlapping as well as the crystal-field splitting of the molybdenum 4d level is discussed.
Thirteen-band tight-binding model for the MoS2 monolayer
(2021-01-01) Meneghetti Junior, Luiz Antonio [UNESP]; Bruno-Alfonso, Alexys [UNESP]; Universidade Estadual Paulista (UNESP)
A tight-binding model is fitted to density-functional calculations of the electronic structure of the MoS2 monolayer. The model involves 13 atomic orbitals per unit cell: the 4d orbitals of the molybdenum atom plus the 3s and 3p orbitals of each sulfur atom. The hopping and overlap couplings of each atom with its first nearest neighbors in each crystalline sublattice are considered. Different values are allowed for the intraplane and interplane S-S hopping integrals. A closed-form expression is given for the effective-mass tensor at stationary points. The isotropy of the valence and conduction bands near the edges of the fundamental gap is proven. The role played by the orbital overlapping as well as the crystal-field splitting of the molybdenum 4d level is discussed.
Light localization in one-dimensional photonic crystal heterostructures
(2021-12-01) Tanaue, Helena Borlina [UNESP]; Reyes-Gómez, Ernesto; Bruno-Alfonso, Alexys [UNESP]; Universidade Estadual Paulista (UNESP); Universidad de Antioquia UdeA
Effects of both metamaterial inclusion and lack of inversion symmetry on the localized modes in one-dimensional photonic heterostructures under normal incidence are investigated. Each structure consists of two semi-infinite photonic crystals separated by an interface or by several layers. A general condition for light localization between semi-infinite crystals is given by parallelism between two-dimensional vectors in the electromagnetic (H, E) space. The case of a defective photonic crystal is recovered by joining crystals having the same unit cell. The defect modes display leftward and rightward damped oscillations with the same ratio, even when the unit cell lacks inversion symmetry. Their frequencies are found in good agreement with peaks of the transmittance through truncated structures. In heterostructures including metamaterials, an anomalous exponential decay of the magnetic field is found near one edge of the zero-〈n〉 gap.
Salicylic acid boosts the tio2 and zno-mediated photodegradation of paracetamol
(2021-01-01) Peres, Matheus Ruffo [UNESP]; Pastrello, Bruna [UNESP]; Sambrano, Júlio Ricardo [UNESP]; Morgon, Nelson Henrique; De Souza, Aguinaldo Robinson [UNESP]; Ximenes, Valdecir Farias [UNESP]; Universidade Estadual Paulista (UNESP); Universidade Estadual de Campinas (UNICAMP)
Titanium dioxide (TiO2) and zinc oxide (ZnO) are among the most used catalysts in photodegradation. Paracetamol and salicylic acid are widely used as pharmaceutical drugs. We found that paracetamol is less susceptible to photodegradation compared to salicylic acid. From a chemical perspective, this was not expected since paracetamol is more vulnerable to chemical oxidation. Aiming the comprehension of this phenomenon, studies were performed comparing the efficiency of photodegradation of paracetamol versus salicylic acid and acetophenone versus 4-aminoacetophenone. The presence of amino/amide group decreased the efficiency of degradation significantly. It was also found that salicylic acid improved the degradation of paracetamol when both compounds were present in the reaction medium. The lower efficiency of photodegradation of the amino-based compounds seems to be related to the deactivation of the excited states of the TiO2 and ZnO. Theoretical calculations at the TD-PBE0/6-311++G(3df,2p) high level were performed and corroborated our proposal.

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