J.G. Marakis, J. Chamiço, G. Brenner and F. Durst
Notes that, in a full‐scale application of the Monte Carlo method for combined heat transfer analysis, problems usually arise from the large computing requirements. Here the…
Abstract
Notes that, in a full‐scale application of the Monte Carlo method for combined heat transfer analysis, problems usually arise from the large computing requirements. Here the method to overcome this difficulty is the parallel execution of the Monte Carlo method in a distributed computing environment. Addresses the problem of determination of the temperature field formed under the assumption of radiative equilibrium in an enclosure idealizing an industrial furnace. The medium contained in this enclosure absorbs, emits and scatters anisotropically thermal radiation. Discusses two topics in detail: first, the efficiency of the parallelization of the developed code, and second, the influence of the scattering behavior of the medium. The adopted parallelization method for the first topic is the decomposition of the statistical sample and its subsequent distribution among the available processors. The measured high efficiencies showed that this method is particularly suited to the target architecture of this study, which is a dedicated network of workstations supporting the message passing paradigm. For the second topic, the results showed that taking into account the isotropic scattering, as opposed to neglecting the scattering, has a pronounced impact on the temperature distribution inside the enclosure. In contrast, the consideration of the sharply forward scattering, that is characteristic of all the real combustion particles, leaves the predicted temperature field almost undistinguishable from the absorbing/emitting case.
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Antonio Fabio Di Rienzo, Pietro Asinari, Romano Borchiellini and Sunhash C. Mishra
The purpose of this paper is to present and validate some improvements to the lattice Boltzmann method (LBM) for solving radiative heat transfer in a participating medium…
Abstract
Purpose
The purpose of this paper is to present and validate some improvements to the lattice Boltzmann method (LBM) for solving radiative heat transfer in a participating medium. Validation of the model is performed by investigating the effects of spatial and angular discretizations and extinction coefficient on the solution. The error analysis and the order of convergence of the scheme are also reported.
Design/methodology/approach
LB scheme is derived from the radiative transfer equation, where isotropic scattering and radiative equilibrium condition are assumed. Azimuthal angle is discretized according to the lattice velocities on the computational plane, while, concerning the polar angle, an additional component of the discrete velocity normal to the plane is introduced. Radiative LB scheme is used to solve a 2‐D square enclosure benchmark problem. In order to validate the model, results of LB scheme are compared with a reference solution obtained through a Richardson extrapolation of the results of a standard finite volume method.
Findings
The proposed improvements drastically increase the accuracy of the previous method. Radiative LB scheme is found to be (at most) first order accurate. Numerical results show that solution gets more accurate when spatial and azimuthal angle discretizations are improved, but a saturation threshold exists. With regard to polar angle, minimum error occurs when a particular subdivision is considered.
Originality/value
The paper provides simple but effective improvements to the recently proposed lattice Boltzmann method for solving radiative heat transfer in a participating medium.
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Severino P.C. Marques, Ever J. Barbero and John S.R. Murillo
The purpose of this paper is to present a computationally efficient model to solve combined conduction/radiation heat transfer problems in absorbing, emitting, non‐scattering…
Abstract
Purpose
The purpose of this paper is to present a computationally efficient model to solve combined conduction/radiation heat transfer problems in absorbing, emitting, non‐scattering, non‐gray materials.
Design/methodology/approach
The model is formulated for steady‐state condition and based on an iterative approach where the medium is discretized into finite strips and the extinction spectrum is divided into finite bands to consider the extinction coefficient variation with the wavelength.
Findings
Temperature fields and heat flux distributions are presented to demonstrate the capability of the formulation. It is shown that the model is quite accurate and efficient even for the cases of pure radiation. Differently from other models, the number of iterations required by the model for convergence is very low, even in the cases dominated by radiation.
Originality/value
The model has great potential to contribute with the evaluation and design of materials for thermal insulation, where radiation heat transfer can be the dominant mechanism, such as aerogel materials which are recognized as the solids with the lowest thermal conductivity and are intended to be used in building and construction, aerospace, transportation and other applications.
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Government information and services are increasingly delivered online through the Internet or other digital means. To benefit citizens, such electronic government (e-government…
Abstract
Purpose
Government information and services are increasingly delivered online through the Internet or other digital means. To benefit citizens, such electronic government (e-government) must be incorporated in their government-related information behavior. This study reviews citizens' information behavior in relation to e-government.
Design/methodology/approach
Following procedures for systematic reviews, this study reviews 53 papers about citizens' e-government information behavior.
Findings
The review finds that citizens (1) employ a rich set of quality, accessibility and non-utilitarian criteria in their perception of e-government; (2) use e-government in combination with offline channels; (3) choose channels on the basis of demographic and situational factors; (4) make frequent use of interpersonal sources and (5) may or may not achieve the intended outcome of their e-government information behavior. E-government information behavior has a lot in common with information behaviors in other domains, but it also accentuates certain facets of information behavior, such as the simultaneous use of multiple channels. In addition, mixed findings are common.
Research limitations/implications
Interpersonal sources, both lay and professional, are integral to citizens' e-government information behavior. Yet, theoretical frameworks for understanding information behavior tend to focus on the individual citizen.
Practical implications
On its own, e-government is most suited for simpler problems. More complex problems require an information behavior that combines e-government with interpersonal sources.
Originality/value
E-government shapes how citizens satisfy their government-related information needs. This study provides an overview of the otherwise scattered research on this information behavior.
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Christos Zeris, George Batis, Vassilios Mouloudakis and John Marakis
This paper aims to present results of an experimental investigation on a series of scaled reinforced concrete column elements which were subjected to chloride exposure under…
Abstract
Purpose
This paper aims to present results of an experimental investigation on a series of scaled reinforced concrete column elements which were subjected to chloride exposure under accelerated conditions under a concurrent service axial load, over a period. In the presence of an axial load, directed microcracks of increasing density and width are introduced in the concrete mass, depending on the axial load level. Such cracks are believed to enhance the intrusion rate of chlorides in the concrete, relative to what is obtained in the normally performed unloaded specimen tests.
Design/methodology/approach
Eighteen column specimens were tested over two chloride exposure periods, of duration up to a maximum of six months. Three different service axial load levels were considered, namely, none, 22 per cent and 43 per cent of the normalized axial load capacity of the columns.
Findings
The results indicate that the specimens loaded to the higher axial load, which closely resembles actual service situation of such type of elements, exhibited up to ten times faster rates of induced current flow under a constant applied voltage of 500 mV, compared to the unloaded and less loaded specimens.
Practical implications
It is proven that the presence of axial load influences the rate of chloride ingress in columns and, therefore, should be taken into account in estimating the concrete cover of such elements in durability design.
Originality/value
The influence of axial loading on corrosion rate has not been considered in published experimental and analytical studies of chloride ingression. These studies have typically so far considered the accelerated corrosion of unloaded column specimens.
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Elisa Garrido-Castro, Francisco-José Torres-Peña, Eva-María Murgado-Armenteros and Francisco Jose Torres-Ruiz
The purpose of this study is to critically review consumer knowledge in marketing and propose a future research agenda. Despite the many works that have examined this variable…
Abstract
Purpose
The purpose of this study is to critically review consumer knowledge in marketing and propose a future research agenda. Despite the many works that have examined this variable, given its strong influence on behaviour, it has generally been studied in association with other constructs, and no studies have focused on it in a specific way. Its definition, measurement and approaches to its role and usefulness are superficial and underdeveloped. After structuring and analysing the existing literature, the authors establish, (I) which aspects are of little use to the discipline, and (II) which research lines have the most potential and should be developed and studied in greater depth, to advance and complete the existing consumer knowledge framework.
Design/methodology/approach
A search was undertaken for documents in the main databases in which the term “consumer knowledge” appears in a marketing or consumer context, and a critical and reflexive approach was taken to analyse the main contributions and to structure them by content blocks.
Findings
Five main content blocks were identified. A set of research gaps were detected, mainly related to the lax conceptualisation of the topic, measurement problems and the scarcity of more useful works connected with business management, and several research lines are proposed that complement the existing framework to make it more complete and operational.
Originality/value
This paper offers a critical review and proposes a research agenda for one of the most used but little studied variables in the field of marketing, which may help academics and professionals in the discipline to continue developing useful theories and models.
Objetivo
El objetivo de este trabajo es revisar críticamente el conocimiento del consumidor en marketing y proponer una agenda de investigación futura. A pesar de los numerosos trabajos que han examinado esta variable, dada su fuerte influencia en el comportamiento, generalmente se ha estudiado en asociación con otros constructos, y ningún estudio se ha centrado en ella de manera específica. Su definición, medición y aproximaciones sobre su papel y utilidad son superficiales y poco desarrollados. Después de estructurar y analizar la literatura existente, establecemos (I) qué aspectos tienen poco uso para la disciplina y (II) qué líneas de investigación tienen más potencial y deben ser desarrolladas y estudiadas con mayor profundidad; para avanzar y completar el marco existente sobre conocimiento del consumidor.
Diseño/metodología/enfoque
Se realizó una búsqueda de documentos en las principales bases de datos en las que aparece el término “conocimiento del consumidor” en un contexto de marketing o consumo, y se adoptó un enfoque crítico y reflexivo para analizar las principales contribuciones y estructurarlas por bloques de contenido.
Resultados
Se identificaron cinco bloques principales de contenido. Se detectó un conjunto de huecos de investigación, principalmente relacionados con la laxa conceptualización del tema, problemas de medición y la escasez de trabajos más útiles conectados con la gestión empresarial; y se proponen varias líneas de investigación que complementan el marco existente para hacerlo más completo y operativo.
Originalidad
Este documento ofrece una revisión crítica y propone una agenda de investigación para una de las variables más utilizadas pero poco estudiadas en el campo del marketing, lo que puede ayudar a académicos y profesionales en la disciplina a continuar desarrollando teorías y modelos útiles.
目的
本文旨在对市场营销中的消费者知识进行批判性审视, 并提出未来的研究议程。虽然已有许多研究检验了该变量, 但由于其对行为产生强大影响, 通常会与其他结构变量一起研究, 而没有以特定方式专注于该变量。对其定义、测量以及其作用和用途的方法仍旧存在研究空白。通过对现有文献进行结构化分析后, 确定了以下两个方面:(I)哪些方面对该学科意义不大, (II)哪些研究方向最具研究潜力, 并且应该进一步深入发展和研究, 以推进和完善现有的消费者知识框架。
设计/方法/途径
通过主要数据库检索市场营销或消费者背景下涉及“消费者知识”一词的文献, 采取批判性和反思性方法来分析其主要贡献, 并通过内容块对其进行结构化。
发现
识别了五个主要内容块, 并发现存在一定程度的研究空白, 主要涉及该主题的概念松散化、测量问题以及与商业管理相关的有效研究的稀缺性。此外, 本文提出了几个研究线索, 这些线索为现有框架补充了信息, 使其更加完整且具备更强的操作性。
独创性
本文对市场营销领域中广泛使用但研究较少的变量进行了批判性评述, 并提出了相关研究议程。这一工作有助于学术界和专业人士继续发展实用的理论和模型。
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This paper seeks to review the literature on methods for solving the radiative transfer equation (RTE) and integrating the radiant energy quantities over the spectrum required to…
Abstract
Purpose
This paper seeks to review the literature on methods for solving the radiative transfer equation (RTE) and integrating the radiant energy quantities over the spectrum required to predict the flow, the flame and the thermal structures in chemically reacting and radiating combustion systems.
Design/methodology/approach
The focus is on methods that are fast and compatible with the numerical algorithms for solving the transport equations using the computational fluid dynamics techniques. In the methods discussed, the interaction of turbulence and radiation is ignored.
Findings
The overview is limited to four methods (differential approximation, discrete ordinates, discrete transfer, and finite volume) for predicting radiative transfer in multidimensional geometries that meet the desired requirements. Greater detail in the radiative transfer model is required to predict the local flame structure and transport quantities than the global (total) radiation heat transfer rate at the walls of the combustion chamber.
Research limitations/implications
The RTE solution methods and integration of radiant energy quantities over the spectrum are assessed for combustion systems containing only the infra‐red radiating gases and gas particle mixtures. For strongly radiating (i.e. highly sooting) and turbulent flows the neglect of turbulence/radiation interaction may not be justified.
Practical implications
Methods of choice for solving the RTE and obtaining total radiant energy quantities for practical combustion devices are discussed.
Originality/value
The paper has identified relevant references that describe methods capable of accounting for radiative transfer to simulate processes arising in combustion systems.
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Xusen Cheng, Shuang Zhang and Bo Yang
Information overload has become ubiquitous during a public health emergency. The research purpose is to examine the role of mixed emotions in the influence of perceived…
Abstract
Purpose
Information overload has become ubiquitous during a public health emergency. The research purpose is to examine the role of mixed emotions in the influence of perceived information overload on individuals’ information avoidance intention and the state of fear of missing out.
Design/methodology/approach
A mixed-methods approach was used in this study: a qualitative study of 182 semi-structured interviews and a quantitative study of 309 surveys.
Findings
The results show that perceived information overload negatively affects peace of mind and positively affects fatigue and fear. Emotions with a low activation level (peace of mind and fatigue) promote emotions with a high activation level (hope and fear), and peace of mind negatively influences fatigue. Additionally, peace of mind negatively affects information avoidance intention, while hope positively affects the state of fear of missing out. These two information processing outcomes are positively impacted by fatigue and fear.
Originality/value
This study extends existing knowledge by uncovering the underlying influence of mixed emotions on individuals’ different information processing outcomes caused by perceived information overload. It provides practical insights for online media platforms and Internet users regarding how to process overwhelming information during a public health emergency.
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Vassiliki Costarelli and Maria Michou
The pandemic of COVID-19 led to considerable challenges with respect to people's health, dietary behavior and satisfaction with life. This study aims to investigate perceived…
Abstract
Purpose
The pandemic of COVID-19 led to considerable challenges with respect to people's health, dietary behavior and satisfaction with life. This study aims to investigate perceived stress levels, in relation to diet quality and life satisfaction in Greek adults, during the COVID-19 lockdown.
Design/methodology/approach
This is a cross-sectional study which took place in Greece in the course of the strict lockdown period, in the third COVID-19 wave. A sample of 2,029 adults aged 18 years and above participated in an online survey. The questionnaire consisted of questions on sociodemographic and anthropometric characteristics. The Perceived Stress Scale, the Satisfaction with Life Scale and the Mediterranean Diet Assessment Tool were also used.
Findings
Linear regression has shown that women (p < 0.0001), younger individuals (p < 0.0001), obese individuals (p = 0.047), those with lower levels of satisfaction with life (p < 0.0001) and lower adherence to Mediterranean diet (p = 0.0001) were positively associated with higher levels of stress.
Originality/value
To the best of the authors’ knowledge, this is the first study conducted in Greece aiming at investigating concurrently, levels of perceived stress, with respect to levels of satisfaction with life and diet quality in adults, during the lockdown period of the COVID-19 pandemic.
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Shao Quan Liu and Marlene Tsao
Spoilage due to yeast and mould growth is a major issue for yoghurt quality and shelf‐life. There is a need to develop natural alternatives to chemical preservation. The purpose…
Abstract
Purpose
Spoilage due to yeast and mould growth is a major issue for yoghurt quality and shelf‐life. There is a need to develop natural alternatives to chemical preservation. The purpose of this paper is to determine the effectiveness of mycocinogenic yeast Williopsis saturnus var. saturnus as a biocontrol agent against spoilage yeasts and moulds in plain yoghurt.
Design/methodology/approach
Yoghurts were prepared from reconstituted skim milk and were challenged with spoilage yeasts and moulds. The treatment contained the added mycocinogenic yeast and the control without. All yoghurts were incubated at 30○C. Yeast and mould growth were determined by observing gas formation and mould colony occurrence at regular intervals.
Findings
W. saturnus var. saturnus inhibited growth of lactose‐fermenting and galactose‐fermenting yeasts (Candida kefir and Kluvyveromyces marxianus), and lactose non‐fermenting but galactose fermenting yeasts (strains of Saccharomyces cerevisiae and Saccharomyces bayanus). The yeast also inhibited growth of dairy moulds including Byssochlamys, Eurotium and Penicillium.
Research limitations/implications
The inhibition of this mycocinogenic yeast against yeasts and moulds was dependent upon the concentration of the latter. Thus, hygiene and good manufacturing practice are essential in order to keep the contaminant load down and to ensure the effectiveness of the mycocinogenic yeast.
Originality/value
The use of mycocinogenic yeast to control spoilage yeasts and moulds in yoghurt is a novel approach with a potential to minimise yoghurt spoilage and extend the shelf‐life of yoghurt.