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1
artículo
Publicado 2000
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[Y1-xCax]SrBaCu2.80(PO4)0.20Oy samples with 0.10 ≤ x ≤ 0.40 were syntherized using the solid state reaction technique. X-ray diffraction patterns show that all the compounds crystallized into a 123 tetragonal structure. The analysis of the structure with Rietveld refinement were made using a model that contains one Cu(2) in four coordination and not in five coordination as in the other 123 tetragonal structures. This fact allows that Tc increase with Ca concentration. All samples are superconductors as reported in a previous paper.
2
artículo
Publicado 2000
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(PO4)3- doped [Y0.75Ca0.25]SrBaCu3-x(PO4)xOy compounds with 0.00 ≤ x ≤ 0.30 were synthesized using the solid state reaction technique at normal pressure and temperture conditions. The X-ray diffraction patterns show that for x= 0.0 the samples crystallize into an orthorhombic phase, and for other x values the samples presented a tetragonal structure. The Rietveld method was used to refine the lattice constants. The analysis of structure with Rietveld refinement was done using a model that contains one Cu(2) in a four coordination and not in five coordination in the other 123 tetragonal structures. All samples are superconductors as reported previously [1].
3
artículo
Publicado 2022
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Purpose – Much research has been conducted on how consumption is related to human relationships. Only a scarcity of studies has examined brand and product selection, as well as the consumption activities that individuals follow when pursuing a sense of group belonging. The literature comprises a single theoretical framework describing this phenomenon, a nascent proposition on which further research remains undeveloped. This study aims to examine the transferability of that theoretical framework in a different context to that used for its elaboration and its descriptive scope on purchasing goods and engaging inn consumption activities to leverage belonging. Design/methodology/approach – A deductive qualitative case study and pattern matching analysis technique were used, followed by structural coding analysis of interview data. Findings – Findings reveal that the model is transferab...
4
artículo
This paper presents a static analysis of functionally graded plates (FGPs) by using a new first shear deformation theory (FSDT). This theory contains only four unknowns, with is even less than the classical FSDT. In this paper a simply supported FG square sandwich plate is subjected to a bi-sinusoidal load. The governing equations for static bending analysis are derived by employing the principle of virtual works. These equations are then solved via Navier-type, closed form solutions. The accuracy of the present theory is ascertained by comparing it with various available solutions in the literature.
5
artículo
Publicado 2017
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In this study, magnetic nanocomposites were developed and used as adsorbents for lead and copper from aqueous media. Structural, surface, magnetic and textural properties of functionalized maghemite nanoparticles synthesized by alkaline co-precipitation were studied. The surfaces of the iron oxide nanoparticles (Nps) were modified with different chemical agents such as fatty and amino acids, silica (SiO2), mesoporous silica (SBA-15), hydroxyapatite, multiwall carbon nanotubes (MWCNTs) and ethylenediaminetetraacetic acid (EDTA), obtaining NPs with mean particle sizes ranging from 7 to 16 nm according to Rietveld refinement and TEM images analysis. The physicochemical surface properties of the functionalized materials were studied via zeta potential (z) and Fourier transform infrared (FTIR) spectroscopy. Mossbauer spectroscopy (MS) as a function of temperature and DC magnetometry were ¨ u...
6
artículo
Publicado 2012
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In this work we report the structural and electronic properties of the compound [Y0.8Ca0.2](Ba0.5Sr0.5)2Cu3O7-δ (YCaBaSr) which is a superconductor below the critical temperature TC = 80 K. This compound was prepared using the Sol-Gel method. The structural properties were studied by X-ray diffraction and electronic properties were studied by X-ray Photoemission Spectroscopy (XPS). The results were compared with those ones of the traditional superconductor YBa2Cu3O7-δ (YBCO). The X-ray photoemission spectra were taken at room temperature (normal state) and at 30 K (superconductor state). In the superconductor state, the X-ray photoemission spectra showed a shift in the O 1s. While the position of the Cu3p principal peaks do not change when measuring at 30 K. However, the spectra reveal the appearance of a new peak due to de hybridization of the Cu3d and O2p states. In addition, the Fou...
7
artículo
Publicado 2021
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Disordered crystalline Fe50Mn25+xSn25?x alloys, with x =-1.25, 0.0, 2.5, 5.0, 7.5 (close to the full-Heusler alloys), were arc-melted in a high purity argon atmosphere and the molten pellets were individually sealed in quartz tubes also under argon atmosphere. Subsequently, they were annealed at 1173 K for 4 days, being finally quenched in a bath with cold water. Structural and magnetic properties have systematically been studied using X-ray diffraction,57Fe, and119Sn Mössbauer spectroscopies, and magnetization measurements recorded at room temperature. Rietveld refinement of the X-ray diffraction patterns of the annealed samples with x =-1.25 and 0 has revealed the presence of two hexagonal crystallographic phases: (i) a chemically disordered solid solution identified as ??(Fe/Mn)3Sn (majority fraction) and (ii) the ??Fe5Sn3 intermetallic compound (minority fraction). For samples with ...
8
artículo
Publicado 2018
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This paper presents Best Theory Diagrams (BTDs) constructed from non-polynomial terms to identify best shell theories for the free vibration analysis of laminated and sandwich shell. The shell theories have been constructed using Axiomatic/Asymptotic Method (AAM). The refined models are implemented following the compactness of a unified formulation developed. The governing equations are derived from the Hamilton’s Principle. NavierType solution technique is used for solving the eigenvalue problem of simply supported shell. The BTDs use 3D equilibrium solutions as a reference. The BTDs built from non-polynomial functions are compared with Maclaurin expansions. The results are compared with Layerwise solutions. Cylindrical and spherical shells with different layer-configurations are investigated. The results demonstrate that the shell models obtained from the BTD using non-polynomial ter...
9
artículo
Publicado 2012
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En este trabajo se reporta las propiedades estructurales y electrónicas del compuesto [Y0.8Ca0.2](Ba0.5Sr0.5)2Cu3O7-δ (YCaBaSr) que es superconductor con temperatura crítica TC = 80 K. El compuesto fue preparado mediante el método Sol-Gel. Las propiedades estructurales y electrónicas de este compuesto se estudiaron mediante difracción de rayos X (DRX) y espectroscopia de fotoemisión de rayos X (XPS) respectivamente. Los resultados fueron comparados con los del superconductor tradicional YBa2Cu3O7- δ (YBCO). Las medidas por XPS se realizaron a temperatura ambiente (en el estado normal) y a 30 K (estado superconductor). En el estado superconductor, los espectros XPS de ambos compuestos muestran corrimiento en el pico O 1s. Mientras que, la posición de los picos principales del Cu 3p no cambian de posición al ser medidos a 30 K y 293 K. Sin embargo, se observa en el espectro la ap...
10
tesis de grado
Analysis of the characterization of the adhesion property in intermediate layers of asphalt pavement
Publicado 2025
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The present study analyzes the characterization of adhesion properties in intermediate layers of asphalt pavement, a critical factor influencing road durability and performance. The research is based on a systematic review of scientific literature, highlighting different methodologies for evaluating interlayer bonding, experimental tests, and international standards such as AASHTO, ASTM, and MTC regulations. A comparative analysis was conducted between samples obtained from the “Improvement of the Santa Maria - Santa Teresa - Hydroelectric Machu Picchu Bridge Road” project and laboratory simulations using the LOTTMAN test. The results demonstrate that the amount of tack coat significantly affects interlayer adhesion. Experimental tests confirmed that a tack coat application rate of 0.4 l/m² provides optimal indirect tensile strength (TSR) values, improving mechanical bonding between...
11
tesis de grado
Publicado 2015
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La materia prima fundamental de cualquier ceramista es la arcilla, por lo que la correcta elección de su calidad, tipología y tratamiento determinarán el resultado final de las piezas elaboradas. La arcilla tiene propiedades plásticas, lo que significa que al humedecerla puede ser modelada fácilmente. Al secarse se torna firme y cuando se somete a altas temperaturas ocurren reacciones químicas que, entre otros cambios, causan que la arcilla se convierta en un material permanentemente rígido, denominado cerámica. La arcilla cocida al fuego es uno de los medios más baratos de producir objetos de uso cotidiano. Los factores estructurales de las arcillas influyen en sus propiedades físicas, de ahí la importancia del entendimiento de los efectos térmicos en la estructura del material. En el presente trabajo, muestras de arcilla de la región de Chulucanas, departamento de Piura, s...
12
objeto de conferencia
A digital image may contain objects that can be made up of multiple regions concerning different material properties, physical or chemical attributes. Thus, segmented simplicial meshes with non-manifold boundaries are generated to represent the partitioned regions. We focus on repairing non-manifold boundaries. Current methods modify the topology, geometry or both, using their own data structures. The problem of modifying the topology is that if the mesh has to be post-processed, for instance with the Delaunay refinement, the mesh becomes unsuitable. In this paper, we propose alternatives to repair non-manifold boundaries of segmented simplicial meshes, among them is the Delaunay based one, we use common data structures and only consider 2 and 3 dimensions. We developed algorithms for this purpose, composed of the following tools: relabeling, point insertion and simulated annealing. Thes...
13
artículo
Publicado 2004
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It is known the YBa2Cu30H (Yl23) prepared by the solid reaction method coexists with a green phase Y2BaCu05 (Y211). In this work we study the behavior of the Y211 (pure) overheated at 11 00°C and 1300°C respectively. The starting sample was prepared by the conventional solid reaction method using appropriate amounts of Y203, BaC03 and CuO; the initial sample was green in color. From the X ray diffractogram (XRD) and using the Rietveld refinement we found that the crystalline structure is orthorhombic and belong to the Pnma spatial group. This is the sorne structure as the one found by Michael and Raveau 1 • The starting sample was overheated at 11 00°C under oxygen pressure of 0.1 atm. According with the XRD, there are no significant variations on its structure. Nevertheless after an overheating of 1300°C in the same oxygen pressure, a new phase Y203 with a cubic symmetry together ...
14
artículo
Publicado 2006
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In the present work were making the qualitative and quantitative identification of the main mineralogical phases present in a specimen of clay, to show a method to adjust their crystalline structures and at the same time determine the concentrations of the mineralogical phases present in the specimen of clay. The data were obtained with an Universal Difractómeter and the Hanawalt method was applied for the identification of the phases, for it we use the softwares DRXWIN 2.2 and CreaFit 2.2. The Rietveld refinement were making using the FullProf program, it allowed refine the net parameters, atomic positions and it determine concentrations of the mineralogical phases present in the specimen, at the same time it allows represent graphically refine crystalline structure of each mineralogical phase and the Fourier Map.
15
tesis de maestría
Publicado 2019
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El objetivo de esta tesis es sintetizar el YAlO3. Este material cristalino presenta propiedades ópticas interesantes, además es un material prometedor como matriz cristalina para láser, fósforos, centelladores, medio para registro holográfico, y muchos otros. Se escogió el método de combustión en solución utilizando como combustibles en un caso sólo urea y en otro una mezcla de urea con glicina. En el primer caso se obtuvo una sustancia grumosa muy espesa color marrón oscuro seguido de un tratamiento térmico hasta 700 ◦C por 3 horas, obteniéndose un polvo esponjoso de color blanco el cual fue verificado estar en fase pura de YAlO3 de acuerdo con el método de difracción de rayos X. En el segundo caso se obtuvo directamente un polvo esponjoso de color blanco. El difractograma de rayos X por el método del polvo confirmó la obtención de fase pura de YAlO3. Naturalmente el...
16
artículo
Publicado 2025
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Para estimar el impacto de los terremotos en áreas urbanas, los investigadores convencionalmente utilizan modelos simplificados de estructuras urbanas para simulaciones. Sin embargo, los avances recientes en tecnología ahora permiten predicciones de respuesta ante terremotos más precisas a través de modelos de alta fidelidad y gemelos digitales. Los programas convencionales de generación de mallas pueden producir modelos 3D generales, pero no están optimizados para simulaciones urbanas a gran escala, donde el refinamiento de la malla cerca de las interfaces de los materiales es esencial. En este estudio, desarrollamos un método eficiente basado en la triangulación de Delaunay para simulaciones a escala urbana mediante la partición del modelo 3D en subdominios. El método propuesto utiliza de manera integrada la información del modelo de elevación digital y del modelo de veloci...
17
tesis de maestría
Publicado 2023
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En esta tesis, se propone un conjunto de técnicas opto-digitales para la reconstrucción 3D y donde el color es asociado a piezas arqueológicas. Esto se realiza con el objetivo de obtener un método que permita preservar digitalmente el patrimonio cultural. Para obtener la reconstrucción digital, se proyectan franjas sinusoidales con el fin de codificar información de la topografía de la pieza. En cambio, para obtener el relieve policromado, se proyectan tres perfiles de luz constantes, debido a que la cámara utilizada es monocromática. Posteriormente, las imágenes registradas son procesadas digitalmente en el software MATLAB, el cual controla el proceso completo de reconstrucción 3D de las superficies incluyendo la textura y el color de la pieza. El trabajo se continúa con la reconstrucción a color de cuatro máscaras de diversos colores. Posteriormente para el afinamiento de...
18
artículo
Publicado 2025
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Flame acceleration plays an important role in determining the onset of deflagration-to-detonation transition (DDT) phenomenon that is relevant to novel pressure-gain propulsion and explosion safety research. Accordingly, this work explores the influence of the separation distance between obstacles (S) inside a 1050 mm closed duct on the acceleration of premixed flames fueled by a stoichiometric methane/air mixture at 40 kPa pressure. The studied duct geometry features a 96 mm x 96 mm square cross section and includes five obstacles along the wall with a 75% blockage ratio, each delineated by side dimensions of 96 mm x 96 mm and square holes of 48 mm x 48 mm. Experimental and direct numerical simulations (DNS) techniques are employed here to investigate the flame acceleration dynamics under different operating conditions. More specifically, high-speed video captures the dynamics of ...
19
artículo
Publicado 2025
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This study examines the effect of technostress on boreout syndrome among municipal workers in Lambayeque, Peru, addressing a significant gap in the literature regarding the relationship between technological stressors and workplace disengagement. Using a quantitative, correlational, non- experimental design, data were collected from 300 municipal employees through validated scales measuring technostress (RED-TIC) and boreout syndrome. Structural equation modeling with partial least squares (PLS-SEM) was employed to test the hypothesized relationships. Contrary to theoretical expectations, results revealed a significant negative relationship between technostress and boreout syndrome (β = −0.584; p < 0.001), with a large effect size (f² = 0.519). This paradoxical finding suggests that technological demands may serve as cognitive activators that protect against workplace boredom and dis...
20
tesis de maestría
Publicado 2025
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Esta tesis propone la implementación de estrategias educativas que integran el uso de tecnología en la enseñanza de la transformación de esfuerzos, con el objetivo de fortalecer las competencias de “solución de problemas” y “diseño en ingeniería” en estudiantes de Ingeniería Civil. En particular, se desarrolla el recurso tecnológico Mohr-cito.exe utilizando el lenguaje de programación Python, el cual permite visualizar el estado general de esfuerzos en elementos estructurales típicos, construir el Círculo de Mohr y calcular los esfuerzos normales y cortantes en cualquier plano inclinado. Para validar la propuesta, se documenta una experiencia piloto en la que Mohr-cito.exe se implementa de manera pedagógica en la unidad “Estado de esfuerzos multiaxial” del curso de Mecánica de Materiales en una universidad privada de Lima. La evaluación de su efectividad se bas...
