Incorporating variable viscosity in vorticity-based formulations for Brinkman equations

In this brief note, we introduce a non-symmetric mixed finite element formulation for Brinkman equations written in terms of velocity, vorticity and pressure with non-constant viscosity. The analysis is performed by the classical Babu\v{s}ka-Brezzi theory, and we state that any inf-sup stable finite element pair for Stokes approximating velocity and pressure can be coupled with a generic discrete space of arbitrary order for the vorticity. We establish optimal a priori error estimates which are further confirmed through computational example

Predictors of review sites usage in hotels

The tourism industry has been strongly impacted by the consumer use of review sites. Since review travel sites such as TripAdvisor allowed accommodations to create own profiles with information, hotels began incorporating these actions into their engaging customers programming. Despite the benefits that review sites can offer to customers, hotels and accommodations, its implementation is not developed and exploited in all its possibilities, and little is known about hotels use of this review sites. This study explores the topic trough quantitative methodology, conducting multiple correlation analysis of data obtained from a sample of 301 hotel managers. Managers consider they are committed to this type of platforms and are capable of use it accurately. Also it was found evidence of correlation between use of TripAdvisor and hotel characteristics (size, ownership structure, and category). Furthermore, multiple regression analysis shows competence and commitment as the most important predictors of use intensity

Relief distribution networks : a systematic review

In the last 20 years, Emergency Management has received increasing attention from the scientific community. Meanwhile, the study of relief distribution networks has become one of the most popular topics within the Emergency Management field. In fact, the number and variety of contributions devoted to the design or the management of relief distribution networks has exploded in the recent years, motivating the need for a structured and systematic analysis of the works on this specific topic. To this end, this paper presents a systematic review of contributions on relief distribution networks in response to disasters. Through a systematic and scientific methodology, it gathers and consolidates the published research works in a transparent and objective way. It pursues three goals. First, to conduct an up-to-date survey of the research in relief distribution networks focusing on the logistics aspects of the problem, which despite the number of previous reviews has been overlooked in the past. Second, to highlight the trends and the most promising challenges in the modeling and resolution approaches and, finally, to identify future research perspectives that need to be explored

Stabilized mixed approximation of axisymmetric Brinkman flows

This paper is devoted to the numerical analysis of an augmented finite element approximation of the axisymmetric Brinkman equations. Stabilization of the variational formulation is achieved by adding suitable Galerkin least-squares terms, allowing us to transform the original problem into a formulation better suited for performing its stability analysis. The sought quantities (here velocity, vorticity, and pressure) are approximated by Raviart−Thomas elements of arbitrary order k ≥ 0, piecewise continuous polynomials of degree k + 1, and piecewise polynomials of degree k, respectively. The well-posedness of the resulting continuous and discrete variational problems is rigorously derived by virtue of the classical Babuška–Brezzi theory. We further establish a priori error estimates in the natural norms, and we provide a few numerical tests illustrating the behavior of the proposed augmented scheme and confirming our theoretical findings regarding optimal convergence of the approximate solutions

About the interaction between a laser beam and group IV nanowires: a study of the electromagnetic field enhancement in homogeneous and heterostructured nanowires

The optical properties of semiconductor nanowires (NWs) are object of study because they are the building blocks of the future nanophotonic devices. The high refractive index and its reduced dimension, make them suitable for photon engineering. The study of the interaction between NWs and visible light has revealed resonances of the light absorption/scattering by the NWs. Micro-Raman spectroscopy is used as a characterization method of semiconductor NWs. The relation between the Raman intensity and the incident electromagnetic (EM) field permits to study the light/NW interaction through the micro-Raman spectra of individual NWs. As compared to either metallic or dielectric NWs, the semiconductor NWs add additional tools to modify its interaction with light, for example, the composition, the presence of heterostructures, both axial and radial, doping, and the surface morphology. One presents herein a study of the optical response of group IV semiconductor NWs to visible photons. The study is experimentally carried out through the micro-Raman spectroscopy of different group IV NWs, both homogeneous and heterostructured (SiGe/Si), and the results are analyzed in terms of the EM modeling of the light/NW interaction using finite element methods (FEMs). The heterostructures are seen to produce additional resonances allowing new photonic capacities to the semiconductor NWs.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref VA293U13

Virtual influencers: generation of trust, loyalty and purchase intentions

The objective of this research is to explore the processes of the generation of trust and purchase intentions among followers of virtual influencers. During October and November 2021, an online survey was distributed among active Instagram users who follow the virtual influencer LilMiquela. The model variables were measured using 7-point Likert-type scales validated in previous studies. A total of 167 valid responses were obtained. The model was evaluated using the PLS-SEM technique, with SmartPLS software, version 3.3.3 (Henseler et al., 2018; Ringle & Sarstedt, 2016). Content quality is the variable with the greatest effect on trust, followed by homophily and social attractiveness. Unlike studies into human influencers that have highlighted the key roles of their physical and social attractiveness, this research into virtual influencers highlights the key role of their ability to generate quality content. This may be because Instagram users accept their messages, but are aware they are not real people. Homophily is understood as being the similarity that followers perceive between their beliefs, values, experiences and lifestyles, and those of their influencers; it strengthens trust by creating good feelings and reduced uncertainty among followers, as occurs in communication between humans. Finally, the negative effect of high anthropomorphism is not statistically significant. In the literature this is a controversial topic with very different results, so further study is needed to arrive at more reliable conclusions.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Analysis and approximation of a vorticity-velocity-pressure formulation for the Oseen equations

We introduce a family of mixed methods and discontinuous Galerkin discretisations designed to numerically solve the Oseen equations written in terms of velocity, vorticity, and Bernoulli pressure. The unique solvability of the continuous problem is addressed by invoking a global inf-sup property in an adequate abstract setting for non-symmetric systems. The proposed finite element schemes, which produce exactly divergence-free discrete velocities, are shown to be well-defined and optimal convergence rates are derived in suitable norms. In addition, we establish optimal rates of convergence for a class of discontinuous Galerkin schemes, which employ stabilisation. A set of numerical examples serves to illustrate salient features of these methods

Confinamiento social obligatorio bajo el escenario del Covid 19 y su influencia en la calidad del aire en Lima Metropolitana, 2020

La presente investigación tuvo como área de estudio Lima Metropolitana, donde se tuvo como principal objetivo determinar cuánto se alteró la calidad del aire en Lima Metropolitana con el confinamiento social obligatorio bajo el escenario del COVID-19 en el año 2020, para ello se empleó la investigación de tipo aplicada y un enfoque cuantitativo, además un diseño no experimental ya que las variables no se manipularon y longitudinal debido a que se evaluaron datos en distintos periodos del tiempo. La investigación se basó en estudiar la variación de las concentraciones de material particulado (MP10, MP2.5) y gases (SO2, CO) de Lima Metropolitana, para ello se recaudó data del Servicio Nacional de Meteorología e Hidrología del Perú (SENAMHI) de los meses febrero, marzo, abril y mayo del 2016 al 2020, a través de las estaciones de monitoreo de calidad del aire. Se realizaron cálculos estadísticos con apoyo del software Excel y SPSS Statistics 25 trabajando en periodos semanales, mensuales, cuatrimestrales y anuales. Calculando porcentajes de variación de las fechas programadas. Los resultados mostraron que la concentración de MP10 presentó una reducción del 71% en semana santa del año 2020 respecto a la concentración del mismo periodo registrado en los últimos 4 años, de igual manera la concentración de MP2.5 tuvo una reducción del 58% en semana santa del año 2020 respecto a la concentración registrada en el mismo periodo de los últimos 4 años, además se observó una disminución de la concentración de SO2 del 38% en las últimas semanas de mayo en el año 2020 respecto a la concentración registrada en el mismo periodo de los últimos 4 años y una variación de 50% de la concentración de CO en el año 2020 respecto a la concentración registrada del mismo periodo de los últimos 4 años