Jaco Dirker, Arnaud G. Malan and Josua P. Meyer
This paper aims to investigate thermal geometric optimisation of rectangular heat conductive cooling structures within solid heat‐generating media for the purpose of minimising…
Abstract
Purpose
This paper aims to investigate thermal geometric optimisation of rectangular heat conductive cooling structures within solid heat‐generating media for the purpose of minimising peak temperatures and enabling optimum use of spatial volume within integrated power electronics.
Design/methodology/approach
A vortex‐centred finite volume numerical solver was developed, employing a fully implicit solution algorithm to obtain 3D temperature distributions. By comparing the peak temperatures obtained for a wide range of related cases, optimised cross‐sectional shapes for particular input conditions were obtained.
Findings
Optimum shapes are dependent on seven identified parameters. In cases where a low percentage of volume is occupied by cooling structures, a high tendency exists for continuous thin cooling layers, as opposed to discrete rectangular cooling inserts, to present the best thermal behaviour. At higher volume percentages, the opposite is true.
Practical implications
The reduced dimensions of cooling inserts have caused manufacturability to be a concern. Research has shown that at small dimensional scale ranges the cross‐sectional shape of the cooling insert has little influence on its thermal performance. In such cases little or no thermal advantage or loss is incurred by making use of continuous cooling layers, which are easiest to manufacture.
Originality/value
The tendencies of optimum cooling structure shapes were obtained and described in terms of seven geometric and material property‐related parameters. Thermal performance of individual inserts is not linearly proportional to dimensional scaling and it was found that, at small‐scale ranges, optimisation from a manufacturing viewpoint would not significantly impact on thermal performance.
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Andrew Gavin Bradford Mowat, Wilhelm Johann van den Bergh, Arnaud George Malan and Daniel Wilke
An area of great interest in current computational fluid dynamics research is that of free-surface modelling (FSM). Semi-implicit pressure-based FSM flow solvers typically involve…
Abstract
Purpose
An area of great interest in current computational fluid dynamics research is that of free-surface modelling (FSM). Semi-implicit pressure-based FSM flow solvers typically involve the solution of a pressure correction equation. The latter being computationally intensive, the purpose of this paper is to involve the implementation and enhancement of an algebraic multigrid (AMG) method for its solution.
Design/methodology/approach
All AMG components were implemented via object-oriented C++ in a manner which ensures linear computational scalability and matrix-free storage. The developed technology was evaluated in two- and three-dimensions via application to a dam-break test case.
Findings
AMG performance was assessed via comparison of CPU cost to that of several other competitive sparse solvers. The standard AMG implementation proved inferior to other methods in three-dimensions, while the developed Freeze version achieved significant speed-ups and proved to be superior throughout.
Originality/value
A so-called Freeze method was developed to address the computational overhead resulting from the dynamically changing coefficient matrix. The latter involves periodic AMG setup steps in a manner that results in a robust and efficient black-box solver.
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Hen‐I Yang, Chao Chen, Bessam Abdulrazak and Sumi Helal
A decade and a half after the debut of pervasive computing, a large number of prototypes, applications, and interaction interfaces have emerged. However, there is a lack of…
Abstract
Purpose
A decade and a half after the debut of pervasive computing, a large number of prototypes, applications, and interaction interfaces have emerged. However, there is a lack of consensus about the best approaches to create such systems or how to evaluate them. To address these issues, this paper aims to develop a performance evaluation framework for pervasive computing systems.
Design/methodology/approach
Based on the authors' experience in the Gator Tech Smart House – an assistive environment for the elderly, they established a reference scenario that was used to guide the analysis of the large number of systems they studied. An extensive survey of the literature was conducted, and through a thorough analysis, the authors derived and arrived at a broad taxonomy that could form a basic framework for evaluating existing and future pervasive computing systems.
Findings
A taxonomy of pervasive systems is instrumental to their successful evaluation and assessment. The process of creating such taxonomy is cumbersome, and as pervasive systems evolve with new technological advances, such taxonomy is bound to change by way of refinement or extension. This paper found that a taxonomy for something so broad as pervasive systems is very complex. It overcomes the complexity by focusing the classifications on key aspects of pervasive systems, decided purely empirically and based on the authors own experience in a real‐life, large‐scale pervasive system project.
Originality/value
There are currently no methods or frameworks for comparing, classifying, or evaluating pervasive systems. The paper establishes a taxonomy – a first step toward a larger evaluation methodology. It also provides a wealth of information, derived from a survey of a broad collection of pervasive systems.