• Coupled systems mechanics
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• 제8권2호
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• pp.147-168
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• 2019

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.

• 이베로아메리카
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• 제21권2호
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• pp.115-143
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• 2019

This article analyzes the relationship between Mexican writer Alfonso Reyes and the group of thinkers, writers, and critics that conformed the Ateneo de la Juventud, in order to show the reciprocal influence that existed between them. The article also considers the Ateneo's role in breaking from the old Positivist model and the acceptance of new ideas around spiritualism, youthfulness, the creation of a thinking and critical sphere, and intellectual aristocracy, among others. The relationship between the ideas of the Ateneo de la Juventud and the Mexican Revolution are discussed, as well as the social and cultural practices of dialogue and friendship, which are considered to be key to understanding the manifestations of intellectual sociability that took place at the turn of the century in Mexico and Latin America. The article also presents an overview of the role that the reading of classical texts and modern thinkers (Nietzsche, Schopenhauer, Bergson, Boutroux among others) had for ateneístas, as well as the way in which they preserved an arielista sense of a relationship between knowledge, ethics, and aesthetics as formative keys for the ideas men of their time.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.163-167
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• 2003

In this paper, an air-suspension type RF MEMS inductor is fabricated, and an appropriate de-embedding scheme for 3-dimenstional MEMS structure is applied and verified with inductance calculation algorithm. With the presented de-embedding method, parasitics from contanct pads and feeding lines are effectively and accurately de-embedded using open and short calibration procedure, and only spiral and posts can be characterized as a high-Q inductor structure. The validity of the de-embedding method is verified by the comparison of the measured and calculated inductances of two 1.5 and 2.5 turn square spiral inductors. The open-short de-embedded inductance error is below 5% each case in comparison with the calculated value based on H.M. Greenhouse's algorithm.

• Coupled systems mechanics
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• 제7권6호
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• pp.669-690
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• 2018

This paper deals with numerical modeling of dynamic failure phenomena in rate-sensitive brittle and/or ductile materials. To this end, a two-dimensional continuum viscodamage-embedded discontinuity model, which is based on our previous work (see Do et al. 2017), is developed. More specifically, the pre-peak nonlinear and rate-sensitive hardening response of the material behavior, representing the fracture-process zone creation, is described by a rate-dependent continuum damage model. Meanwhile, an embedded displacement discontinuity model is used to formulate the post-peak response, involving the macro-crack creation accompanied by exponential softening. The numerical implementation in the context of the finite element method exploiting the second-order mid-point scheme is discussed in detail. In order to show the performance of the model several numerical examples are included.

• Coupled systems mechanics
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• 제12권5호
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• pp.461-479
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• 2023

The paper deals with the finite element modelling of the free vibration and structural behavior of a particular four-floor reinforced concrete structure subjected to static equivalent seismic loads and supported by a shallow foundation system called SNSF (Spider Net System Footing). The two FE models are a simple 2D Matlab model and a detailed 3D model based on solid elastic elements using Altairworks (Hypermesh and Optistruct). Both models can simulate the soil structure interaction. We concentrate on the behavior of a representative cell involving two columns on five levels. The influence of the boundary conditions on the external vertical planes of the domain are duly studied. The Matlab model appears relevant for a primary estimation of frequencies and stiffness of the whole structure under vertical and lateral loads.

• 대한수학회보
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• 제51권2호
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• pp.437-442
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• 2014

In this paper we prove Ekeland's variational principle in the setting of locally complete spaces for lower semi continuous functions from above and bounded below. We use this theorem to prove Caristi's fixed point theorem in the same setting and also for lower semi continuous functions.

• 대한수학회보
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• 제40권2호
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• pp.243-251
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• 2003

This note Presents sufficient conditions for Lyapunov's stability and instability of a class of nonlinear nonautonomous second-order ordinary differential equations. Such a class includes as particular cases a remarkably large number of differential equations with specific physical applications. Two successive nonlinear transformations are applied to the original differential equation in order to convert it into a more convenient form for stability analysis purposes. The obtained stability / instability conditions depend closely on the parameterization of the original differential equation.

• Coupled systems mechanics
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• 제8권2호
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• pp.95-98
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• 2019

This special issue contains selected papers first presented in a short format at the Congress CILAMCE 2018 ($39^{th}$ Ibero-Latin American Congress on Computational Methods in Engineering) held in Paris and in $Compi{\grave{e}}gne$, France, from 11 to 14 November 2018.

• Kyungpook Mathematical Journal
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• 제61권2호
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• pp.279-308
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• 2021

The purpose of this paper is to introduce a class of contractive pairs of mappings satisfying a Zamfirescu-type inequality, but controlled with altering distance functions and with parameters satisfying the so-called Geraghty condition in the framework of b-metric spaces. For this class of mappings we prove the existence of points of coincidence, the convergence and stability of the Jungck, Jungck-Mann and Jungck-Ishikawa iterative processes and the existence and uniqueness of its common fixed points.

• Asian-Australasian Journal of Animal Sciences
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• 제16권11호
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• pp.1619-1624
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• 2003

The effect of maize hybrid (Suco and Dekalb 765, DK 765), maturity stage (milk, $R_3$ and 1/2 milk line, $R_5$) and animal diet (Diet 1: 70% lucerne hay+30% maize silage; Diet 2: 50% maize silage+20% sunflower meal+30% maize grain) on ruminal stover dry matter (DM) degradability was studied. Additionally, morphological and chemical plant composition was evaluated. Fodder samples ground at 2 mm were incubated in three Holstein steers (400 kg body weight) using the in situ technique. Ruminal degradation kinetics was studied and the effective degradability (ED) was estimated for an assumed kp of 5%/h. The in situ data was analyzed in a complete randomized block design with the animals as blocks. Significant interactions between hybrid${\times}$diet and maturity${\times}$diet on kinetic digestion parameters were detected. In Diet 1, hybrids did not differ in degradable fraction, kd or ED, although a minor difference (p<0.05) in the soluble fraction was found (25.5 and 23.2% for Suco and DK 765, respectively). In Diet 2, the DK 765 had greater degradable fraction (p<0.001) but smaller (p<0.01) kd than Suco, without differences in the soluble fraction or in ED. Anticipating the harvest increased ED of stover from 37.5% in $R_5$ to 44.6% in $R_3$ (average values across hybrids and diets) due to the increase (p<0.001) in the soluble fraction ($R_5$: 22.6%, $R_3$: 28.8%). It is concluded that hybrids had similar stover in situ DM degradability and that soluble fraction represent the main proportion of degradable substrates. Advancing the date of harvesting may not improve the in situ DM degradability of whole maize plant silage since the increase in stover quality is counteracted by the depression in the grain-to-stover ratio. The diet of the animal consuming silage might not improve stover utilization either.