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1 – 10 of over 32000To introduce a novel numerical calculation procedure for periodically fully developed heat and fluid flow, which can treat three‐dimensional velocity and temperature fields, using…
Abstract
Purpose
To introduce a novel numerical calculation procedure for periodically fully developed heat and fluid flow, which can treat three‐dimensional velocity and temperature fields, using a two‐dimensional storage.
Design/methodology/approach
The three‐dimensional Navier‐Stokes equation and energy equation have been transformed into quasi‐three‐dimensional forms. An appropriate set of explicit periodic boundary conditions have been obtained for thermally fully developed flow through a general three‐dimensional periodic structure, exploiting the volume averaging theory.
Findings
The proposed numerical procedure has been found inexpensive and efficient. Its validity has been proved by comparing the results obtained for a bank of long cylinders in yaw against available experimental data.
Originality/value
Since no explicit sets of periodic boundary conditions of this kind have been reported before, they will be exploited by researchers and practitioners interested in efficient numerical computations of three‐dimensional periodic heat and fluid flows.
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Mohamed S. Gadala and Fuchang Xu
To develop an effective and reliable procedure for the calculation of heat fluxes from the measured temperatures in experimental tests of impingement water cooling.
Abstract
Purpose
To develop an effective and reliable procedure for the calculation of heat fluxes from the measured temperatures in experimental tests of impingement water cooling.
Design/methodology/approach
An inverse heat transfer analysis procedure is developed and implemented into a 2D finite element program. In this method, the least‐squares technique, sequential function specification and regularization are used. Simplifications in the sensitivity matrix calculation and iterative procedures are introduced. The triangular and impulse‐like profiles of heat fluxes simulating practical conditions of impingement water cooling are used to investigate the accuracy and stability of the proposed inverse procedure. The developed program is then used to determine the heat flux during impingement water cooling.
Findings
A hybrid procedure is developed in which inverse calculations are conducted with a computation window. This procedure may be used as a whole time domain method or become a periodically sequential or real sequential method by adjusting the sequential steps.
Originality/value
Parametric study and application show that the developed method is effective and reliable and that inverse analysis may obtain the heat flux with an acceptable level of accuracy.
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Daniela Lucangeli, Patrizio Tressoldi and Chiara De Candia
Italian epidemiological data reveal a large discrepancy between the incidence of learning disabilities in mathematics and simple difficulties in mathematics. The incidence of…
Abstract
Italian epidemiological data reveal a large discrepancy between the incidence of learning disabilities in mathematics and simple difficulties in mathematics. The incidence of dyscalculia (specific learning disability in mathematics) is about 2%, whereas the incidence of students with difficulties in arithmetic is surprisingly greater, estimated by teachers to be about five students out of 25 (that is, 20%). This unexpectedly high number of students with difficulties invites serious consideration of its cause and remedy. In this chapter, we try to answer to these questions in the light of two educational studies aimed at improving calculation abilities and the outcome of an intervention with three single cases with dyscalculia using the model and the materials of an innovative arithmetical curriculum. The results suggest that for most children, their arithmetic difficulties are simple consequences of their math instruction, which may be remediated by integrating traditional math curricula with information derived from the research on the cognitive arithmetical architecture and its development. There are also implications that even the arithmetical difficulties of dyscalculic children may be improved with special training focused on their specific impairments revealed after a detailed assessment.
Computer programs were developed based on the finite element method and the charge simulation method for the calculation of three dimensional electric fields in high voltage…
Abstract
Computer programs were developed based on the finite element method and the charge simulation method for the calculation of three dimensional electric fields in high voltage engineering. A brief description of the applied methods with respect to the special requirements of high voltage engineering is presented. In order to use the specific advantages of the finite element method and the charge simulation method, two procedures combining both methods are proposed: an iterative method and a direct method. For the calculation of three dimensional problems without symmetry the iterative procedure has the advantage that the coupling program is small compared with the field calculation programs and no major changes in these programs are necessary.
Silvia Lanfranchi, Daniela Lucangeli, Olga Jerman and H. Lee Swanson
This chapter reviews research on math disabilities (MD) from two different points of view: Italian and American. Our goal is to gain consensus on identifying the cognitive…
Abstract
This chapter reviews research on math disabilities (MD) from two different points of view: Italian and American. Our goal is to gain consensus on identifying the cognitive deficits that underlie problems associated with MD as well as to provide an overview of some of the instructional approaches to remediate these deficits. The review outlines similarities and differences in the research perspectives between the two countries. Although the results show some consensus on the identification of MD and the cognitive mechanisms associated with this deficit (e.g., working memory), some differences remain between the two research perspectives (e.g., incidence of MD).
Sustainability encapsulates economic, environmental and societal domains. In order to conform to these domains, the efficiency of maintenance and repair of heritage buildings is…
Abstract
Purpose
Sustainability encapsulates economic, environmental and societal domains. In order to conform to these domains, the efficiency of maintenance and repair of heritage buildings is no exception. Emergently, environmental considerations for sustainable heritage buildings repair have become increasingly important. The purpose of this paper is to present a decision-making process based on “Green Maintenance Model” – an appraisal approach based on life cycle assessment (LCA) of paint repair options for heritage buildings.
Design/methodology/approach
Calculation procedures of Green Maintenance model within selected boundaries of LCA enable evaluation of carbon emissions, in terms of embodied carbon expenditure, expended from paint repair for heritage buildings during maintenance phase.
Findings
“Green Maintenance” model could be understood as a carbon LCA of paint repair and has been recognized in reducing carbon emissions. Significantly, the model underpins decision-making for repair options for heritage buildings.
Practical implications
It must be emphasized that the calculation procedures of Green Maintenance model is not limited to heritage buildings and can be applied to any repair types, materials used and building forms. More importantly, this model practically supports environmentally focused conservation and promotes sustainable repair approach.
Social implications
The implementation of Green Maintenance model highlights the efficiency of repairs options that may be adopted.
Originality/value
Green Maintenance shows that generated environmental maintenance impact from repair options relays the “true” embodied carbon expenditure contextualized within the longevity of repair and its embodied carbon. This will consequently allow rationale in appraisal of repair options.
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Gino Cortellessa, Fausto Arpino, Simona Di Fraia and Mauro Scungio
In this work, a new two-phase version of the finite element-based Artificial Compressibility (AC) Characteristic-Based Split (CBS) algorithm is developed and applied for the first…
Abstract
Purpose
In this work, a new two-phase version of the finite element-based Artificial Compressibility (AC) Characteristic-Based Split (CBS) algorithm is developed and applied for the first time to heat and mass transfer phenomena in porous media with associated phase change. The purpose of this study is to provide an alternative for the theoretical analysis and numerical simulation of multiphase transport phenomena in porous media. Traditionally, the more complex Separate Flow Model was used in which the vapour and liquid phases were considered as distinct fluids and mathematically described by the conservation laws for each phase separately, resulting in a large number of governing equations.
Design/methodology/approach
Even though the adopted mathematical model presents analogies with the conventional multicomponent mixture flow model, it is characterized by a considerable reduction in the number of the differential equations for the primary variables. The fixed-grid numerical formulation can be applied to the resolution of general problems that may simultaneously include a superheated vapour region, a two-phase zone and a sub-cooled liquid region in a single physical domain with irregular and moving phase interfaces in between. The local thermal non-equilibrium model is introduced to consider the heat exchange between fluid and solid within the porous matrix.
Findings
The numerical model is verified considering the transport phenomena in a homogenous and isotropic porous medium in which water is injected from one side and heated from the other side, where it leaves the computational domain in a superheated vapour state. Dominant forces are represented by capillary interactions and two-phase heat conduction. The obtained results have been compared with the numerical data available in the scientific literature.
Social implications
The present algorithm provides a powerful routine tool for the numerical modelling of complex two-phase transport processes in porous media.
Originality/value
For the first time, the stabilized AC-CBS scheme is applied to the resolution of compressible viscous flow transport in porous materials with associated phase change. A properly stabilized matrix inversion-free procedure employs an adaptive local time step that allows acceleration of the solution process even in the presence of large source terms and low diffusion coefficients values (near the phase change point).
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Total risk score (TRS) is considered one of the main indicators for risk evaluation. Several studies attempted to employ different types of risk indices for the evaluation of cost…
Abstract
Purpose
Total risk score (TRS) is considered one of the main indicators for risk evaluation. Several studies attempted to employ different types of risk indices for the evaluation of cost overrun causes. Hence, this study aims at performing a comparative analysis to evaluate the efficiency of three different approaches for TRS calculation.
Design/methodology/approach
Thirty-eight unique causes of cost overrun in urban-related construction projects were identified and a survey was conducted among construction professionals in Iran. The TRS for each cost overrun cause is calculated using single-attribute (SA), double-attribute (DA), and multiple-attribute (MA) approaches, and eventually, causes were ranked. Furthermore, principal component analysis (PCA), logistic regression analysis (LRA), and K-means clustering are utilized to compare the differences in the generated TRS using different approaches.
Findings
The results revealed that the TRS generated through the MA approach demonstrated the highest efficiency in terms of generating correlation between causes and their identified latent constructs, prediction capability, and classification of the influential causes in the same group.
Originality/value
The originality of this study primarily stems from the adoption of statistical approaches in the evaluation of the recently introduced TRS calculation approach in comparison to traditional ones. Additionally, this study proposed a modified application of the relative importance index (RII) for risk prioritization. The results from this study are expected to fulfill the gap in previous literature toward exploring the most efficient TRS calculation approach for those researchers and practitioners who seek to utilize them as a measure to identify the influential cost overrun causes.
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Domingos António Ribas and Paulo Cachim
The purpose of this paper is to present an innovative approach for the development of a methodology to systematically assess the economic performance and for the assessment of the…
Abstract
Purpose
The purpose of this paper is to present an innovative approach for the development of a methodology to systematically assess the economic performance and for the assessment of the economic sustainability of a building, through the calculation of an economic sustainability index, within the sustainability framework according to the rules defined in EN 16627.
Design/methodology/approach
The methodology follows the principle of modularity, where aspects and impacts that influence the economic performance of the building during the phases of its life cycle are assigned to levels. It presents a model based on the construction costs of the building. The methodology in centered in the before use phase and restricted to residential buildings.
Findings
Definition of a model for assessing the economic performance and calculation of an economic sustainability index.
Research limitations/implications
The methodology is focused only in the before use phase of the buildings, assuming they have the same functional equivalent. It can be expanded to include the other phases of the building life cycle.
Practical implications
The developed methodology will allow the selection of construction procedures, based on economic sustainability, contributing to more rational and support decisions.
Social implications
Contributing to a more sustainable society.
Originality/value
The European framework of EN 15643 and EN 16627 for the assessment of building sustainability is new and, as such, not implemented in most practical tools. Also, economic sustainability is not usually considered in detail in existing models. This paper presents a methodology following the framework and, simultaneously, possible to integrate in existing approaches.
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