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Juan Carlos González Gómez,Kevin Herman Muraro Gularte,José Alfredo Ruiz Vargas,Rogério Rodrigues dos Santos,José Antonio Ruz Hernández 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.9
This paper presents the synchronization of a class of hyperchaotic systems using a robust underactuated approach. The proposed scheme guarantees the convergence in finite time of the slave system trajectories to the master system based on Lyapunov theory. The main novelty of the method is its simplicity resulting from the underactuated strategy and its robustness due to the presence of disturbances in the stability analysis. Simulations are presented to show the performance of the proposed method and its advantages compared with another recent study in the literature. In addition, a secure communication example is considered to illustrate the simple application of the synchronizer.
Computational Modeling of Waves in Composite Saturated Poroviscoelastic Media
Juan E. Santos,Dongwoo Sheen 한국산업응용수학회 2005 한국산업응용수학회 학술대회 논문집 Vol.- No.-
Wave propagation in composite porous materials has applications in many branches of science and technology, such as seismic methods in the presence of shaley sandstones [1], frozen or partially frozen sandstones [12,3,4], gas-hydrates in ocean-bottom sediments [5] and evaluation of the freezing conditions of foods by ultrasonic techniques [10]. A theory to describe wave propagation in frozen porous media was first presented by Leclaire et al. [8]. This model, valid for uniform porosity, predicts the existence of three compressional and two shear waves; the verification that additional (slow) waves can be observed in laboratory experiments was published by Leclaire et al. [9]. Later, Carcione and Tinivella [5] generalized this theory to include the interaction between the solid and ice particles and grain cementation with decreasing temperature. Also, Carcione et al. [1] applied this theory to study the acoustic properties of shaley sandstones, assuming that sand and clay are non-welded and form a continuous and inter-penetrating porous composite skeleton. Both frozen porous media and shaley sandstones are two examples of porous materials where the two solid phases are weakly-coupled or non-welded, i.e, both solids form a continuous and interacting composite structure, interchanging mechanical energy. Similar weakly-coupled formulations have previously been proposed. For instance, McCoy [11] has proposed a mixture theory appropriate for the combination of two acoustic phases. This work presents a differential and numerical model to describe wave propagation in a heterogeneous poroviscolastic frame consisting of two weakly-coupled solid phases saturated by a single phase fluid. The equations of motion, stated in the space-frequency domain, generalizes that presented in [15] and [2] by the inclusion of solid matrix dissipation using a linear viscoelastic model and frequency dependent mass and viscous coupling coefficients. It also generalizes the models of Leclaire et al. [8] and Carcione et al. [5] for the case of uniform porosity, and consequently is the appropriate model to perform numerical simulation in heterogeneous materials. The numerical procedures presented employ the nonconforming rectangular element defined in [7] to approximate the displacement vector in the solid phases. The dispersion analysis presented in [16] shows that employing this nonconforming element allows for a reduction in the number of points per wavelength necessary to reach a desired accuracy. On the other hand, the displacement in the fluid phase is approximated by using the vector part of the Raviart-Thomas-Nedelec mixed finite element space of zero order, which is a conforming space [14,13]. The error analysis yields optimal a priori error estimates for the global standard and hybridized Galerkin methods. Numerical simulation of waves in porous media is computationally expensive due to a large number of degrees of freedom needed to calculate wave fields accurately; the use of a domain decomposition iteration is a convenient approach to overcome this difficulty. Here we define a nonoverlapping domain decomposition iterative scheme and derive convergence results similar to those presented in [6] for solving second-order elliptic problems. This iterative procedure was used for the simulation of waves in a sample of water saturated partially frozen Berea sandstone [2,5], perturbed by a point source at seismic frequencies. The sample has an interior plane interface defined by a change in ice content in the pores, and the snapshots of the generated wave fields show clearly the events associated with the different types of waves.
The textile products labelling analysis and requirements
Luna Santos-Roldán,Beatriz Palacios-Florencio,Juan Manuel Berbel-Pineda 한국의류학회 2020 Fashion and Textiles Vol.7 No.1
The textile sector is one of the most representative of Spanish industry, contributing to the wealth of the country with close to 10% of the business fabric in Spain. However, in spite of this daily consumption little is known about the guarantees of traceability clothes labelling must inform about. The purpose of this study is to present a work of analysis of the compliance with the content of the labelling in this sector. For his objective, a research was developed through the consideration of 32 businesses of the textile sector in the city of Córdoba (Spain) where were photographed each label for its later analysis and a confirmation of the regulation. The results show that the majority of labels are incomplete and insufficient. Therefore, it’s necessary the existence of an European public organism with a competence to accredit the manufacturing, distribution and commercialization of textile garments, protecting the rights of workers and the consumers’ access to information.
Numerical simulation of non-isothermal flow in oil reservoirs using a two-equation model
dos Santos Heringer, Juan Diego,de Souza Debossam, Joao Gabriel,de Souza, Grazione,Souto, Helio Pedro Amaral Techno-Press 2019 Coupled systems mechanics Vol.8 No.2
This work aims to simulate three-dimensional heavy oil flow in a reservoir with heater-wells. Mass, momentum and energy balances, as well as correlations for rock and fluid properties, are used to obtain non-linear partial differential equations for the fluid pressure and temperature, and for the rock temperature. Heat transfer is simulated using a two-equation model that is more appropriate when fluid and rock have very different thermal properties, and we also perform comparisons between one- and two-equation models. The governing equations are discretized using the Finite Volume Method. For the numerical solution, we apply a linearization and an operator splitting. As a consequence, three algebraic subsystems of linearized equations are solved using the Conjugate Gradient Method. The results obtained show the suitability of the numerical method and the technical feasibility of heating the reservoir with static equipment.
REAL HYPERSURFACES IN COMPLEX SPACE FORMS WITH ε-PARALLEL RICCI TENSOR AND STRUCTURE JACOBI OPERATOR
Ki, U-Hang,Perez Juan De Dios,Santos Florentino G.,Suh Young-Jin Korean Mathematical Society 2007 대한수학회지 Vol.44 No.2
We know that there are no real hypersurfaces with parallel Ricci tensor or parallel structure Jacobi operator in a nonflat complex space form (See [4], [6], [10] and [11]). In this paper we investigate real hypersurfaces M in a nonflat complex space form $M_n(c)$ under the condition that ${\nabla}_{\varepsilon}S=0\;and\;{\nabla}_{\varepsilon}R_{\varepsilon}=0,\;where\;S\;and\;R_{\varepsilon}$ respectively denote the Ricci tensor and the structure Jacobi operator of M in $M_n(c)$.
Reactivity of hydroxyl radicals with neonicotinoid insecticides: mechanism and changes in toxicity
Dell'Arciprete, Maria L.,Santos-Juanes, Lucas,Sanz, Antonio Arques,Vicente, Rafael,Amat, Ana M.,Furlong, Jorge P.,Martirea, Daniel O.,Gonzalez, Monica C. Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.7
The reactivity of hydroxyl radicals ($HO^{\cdot}$) towards three neonicotonoid insecticides, namely imidacloprid, thiacloprid and acetamiprid was investigated. These radicals were generated by photolysis of $H_2O_2$ solutions. Flash photolysis experiments were used to determine the rate constants of $5.5{\times}10^{10}M^{-1}s{-1}$, $6{\times}10^{10}M^{-1}s^{-1}$, and $7.5{\times}10^{10}M^{-1}s^{-1}$, for the reactions of $HO^{\cdot}$ with acetamiprid, imidacloprid, and thiacloprid, respectively. Continuous irradiation experiments in the absence and presence of $H_2O_2$ allowed the identification and toxicity evaluation of the primary photo- and oxidation products of the insecticides. In all cases, the less toxic 6-chloronicotinic acid was found to be the major product at higher degrees of oxidation. The results reported here indicate that the half life of the insecticides due to their reaction with $HO^{\cdot}$ radicals in natural aquatic reservoirs may vary between 5 h and 19 days, and therefore the hydroxyl radical-mediated oxidation may be a significant abiotic elimination route. However, elimination of the insecticide under such conditions might not improve the quality of the contaminated water, as the primary products of degradation still show considerable toxicity to Vibrio fischeri assays.
De Dios Perez, Juan,Santos, Florentino Garcia Department of Mathematics 2009 Kyungpook mathematical journal Vol.49 No.2
We classify real hypersurfaces in complex projective space whose structure Jacobi operator satisfies a certain cyclic condition.
Numerical simulation of single-phase two-components flow in naturally fractured oil reservoirs
Debossam, Joao Gabriel Souza,dos Santos Heringer, Juan Diego,de Souza, Grazione,Souto, Helio Pedro Amaral Techno-Press 2019 Coupled systems mechanics Vol.8 No.2
The main goal of this work is to develop a numerical simulator to study an isothermal single-phase two-component flow in a naturally fractured oil reservoir, taking into account advection and diffusion effects. We use the Peng-Robinson equation of state with a volume translation to evaluate the properties of the components, and the discretization of the governing partial differential equations is carried out using the Finite Difference Method, along with implicit and first-order upwind schemes. This process leads to a coupled non-linear algebraic system for the unknowns pressure and molar fractions. After a linearization and the use of an operator splitting, the Conjugate Gradient and Bi-conjugated Gradient Stabilized methods are then used to solve two algebraic subsystems, one for the pressure and another for the molar fraction. We studied the effects of fractures in both the flow field and mass transport, as well as in computing time, and the results show that the fractures affect, as expected, the flow creating a thin preferential path for the mass transport.