Mani Sekaran Santhanakrishnan, Timothy Tilford and Christopher Bailey
This study aims to provide an insight into the relationship between design parameters and thermal performance of plate fin heat sinks (PFHSs) incorporating longitudinal vortex…
Abstract
Purpose
This study aims to provide an insight into the relationship between design parameters and thermal performance of plate fin heat sinks (PFHSs) incorporating longitudinal vortex generators (VGs) inside a PFHS channel.
Design/methodology/approach
A computational fluid dynamics model of a delta winglet pair VG mounted inside a PFHS geometry is detailed, and the model is validated by comparison with experimental data. The validated model is used to perform a virtual design of experiments study of the heat sink with bottom plate and vertical plate mounted VGs. Data from this study is used to regress a response surface enabling the influence of each of the assessed design variables on thermal performance and flow resistance to be determined.
Findings
The results of this study show that the thermal hydraulic performances of a PFHS with bottom plate mounted VG and vertical plate fin mounted VG are, respectively, 1.12 and 1.17 times higher than the baseline PFHS. Further, the performance variation of the heat sink with VG, relative to delta winglet’s arrangement (common flow up and common flow down), trailing edge gap length and Reynolds number were also evaluated and reported.
Originality/value
For the first time, performance characteristics of delta winglet VGs mounted inside the PFHS are evaluated against different design variables and a polynomial regression model is developed. The developed regression model and computed results can be used to design high performance PFHSs mounted with delta winglet VGs.
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Mani Sekaran Santhanakrishnan, Tim Tilford and Chris Bailey
The purpose of the study is to optimise the cross-sectional shape of passively cooled horizontally mounted pin-fin heat sink for higher cooling performance and lower material…
Abstract
Purpose
The purpose of the study is to optimise the cross-sectional shape of passively cooled horizontally mounted pin-fin heat sink for higher cooling performance and lower material usage.
Design/methodology/approach
Multi-objective shape optimisation technique is used to design the heat sink fins. Non-dominated sorting genetic algorithm (NSGA-II) is combined with a geometric module to develop the shape optimiser. High-fidelity computational fluid dynamics (CFD) is used to evaluate the design objectives. Separate optimisations are carried out to design the shape of bottom row fins and middle row fins of a pin-fin heat sink. Finally, a computational validation was conducted by generating a three-dimensional pin-fin heat sink using optimised fin cross sections and comparing its performance against the circular pin-fin heat sink with the same inter-fin spacing value.
Findings
Heat sink with optimised fin cross sections has 1.6% higher cooling effectiveness than circular pin-fin heat sink of same material volume, and has 10.3% higher cooling effectiveness than the pin-fin heat sink of same characteristics fin dimension. The special geometric features of optimised fins that resulted in superior performance are highlighted. Further, Pareto-optimal fronts for this multi-objective optimisation problem are obtained for different fin design scenarios.
Originality/value
For the first time, passively cooled heat sink’s cross-sectional shapes are optimised for different spatial arrangements, using NSGA-II-based shape optimiser, which makes use of CFD solver to evaluate the design objectives. The optimised, high-performance shapes will find direct application to cool power electronic equipment.
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T. Tilford, K.I. Sinclair, C. Bailey, M.P.Y. Desmulliez, G. Goussettis, A.K. Parrott and A.J. Sangster
This paper aims to present an open‐ended microwave curing system for microelectronics components and a numerical analysis framework for virtual testing and prototyping of the…
Abstract
Purpose
This paper aims to present an open‐ended microwave curing system for microelectronics components and a numerical analysis framework for virtual testing and prototyping of the system, enabling design of physical prototypes to be optimized, expediting the development process.
Design/methodology/approach
An open‐ended microwave oven system able to enhance the cure process for thermosetting polymer materials utilised in microelectronics applications is presented. The system is designed to be mounted on a precision placement machine enabling curing of individual components on a circuit board. The design of the system allows the heating pattern and heating rate to be carefully controlled optimising cure rate and cure quality. A multi‐physics analysis approach has been adopted to form a numerical model capable of capturing the complex coupling that exists between physical processes. Electromagnetic analysis has been performed using a Yee finite‐difference time‐domain scheme, while an unstructured finite volume method has been utilized to perform thermophysical analysis. The two solvers are coupled using a sampling‐based cross‐mapping algorithm.
Findings
The numerical results obtained demonstrate that the numerical model is able to obtain solutions for distribution of temperature, rate of cure, degree of cure and thermally induced stresses within an idealised polymer load heated by the proposed microwave system.
Research limitations/implications
The work is limited by the absence of experimentally derived material property data and comparative experimental results. However, the model demonstrates that the proposed microwave system would seem to be a feasible method of expediting the cure rate of polymer materials.
Originality/value
The findings of this paper will help to provide an understanding of the behaviour of thermosetting polymer materials during microwave cure processing.
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Stoyan Stoyanov, Tim Tilford, Farid Amalou, Scott Cargill, Chris Bailey and Marc Desmulliez
Nano‐imprint forming (NIF) is a manufacturing technology capable of achieving high resolution, low‐cost and high‐throughput fabrication of fine nano‐scale structures and patterns…
Abstract
Purpose
Nano‐imprint forming (NIF) is a manufacturing technology capable of achieving high resolution, low‐cost and high‐throughput fabrication of fine nano‐scale structures and patterns. The purpose of this paper is to use modelling technologies to simulate key process steps associated with the formation of patterns with sub‐micrometer dimensions and use the results to define design rules for optimal imprint forming process.
Design/methodology/approach
The effect of a number of process and pattern‐related parameters on the quality of the fabricated nano‐structures is studied using non‐linear finite element analysis. The deformation process of the formable material during the mould pressing step is modelled using contact analysis with large deformations and temperature dependent hyperelastic material behaviour. Finite element analysis with contact interfaces between the mould and the formable material is utilised to study the formation of mechanical, thermal and friction stresses in the pattern.
Findings
The imprint pressure, temperature and the aspect ratio of grooves which define the pattern have significant effect on the quality of the formed structures. The optimal imprint pressure for the studied PMMA is identified. It is found that the degree of the mould pattern fulfilment as function of the imprint pressure is non‐linear. Critical values for thermal mismatch difference in the CTE between the mould and the substrate causing thermally induced stresses during cooling stage are evaluated. Regions of high stresses in the pattern are also identified.
Originality/value
Design rules for minimising the risk of defects such as cracks and shape imperfections commonly observed in NIF‐fabricated nano‐structures are presented. The modelling approach can be used to provide insights into the optimal imprint process control. This can help to establish further the technology as a viable route for fabrication of nano‐scale structures and patterns.
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Jennifer S. Reinke and Catherine A. Solheim
Using Andersen’s (1968) behavioral model of health services use as a guiding conceptual framework, this study examined how receipt of family-centered care relates to the perceived…
Abstract
Purpose
Using Andersen’s (1968) behavioral model of health services use as a guiding conceptual framework, this study examined how receipt of family-centered care relates to the perceived family challenges for families of children with autism spectrum disorder (ASD).
Design
Data from the 2009–2010 National Survey of Children with Special Health Care Needs (NS-CSHCN) were analyzed for 812 parents of children with ASD.
Findings
Multiple regression analyses provided substantive statistical evidence that a child’s race, the adequacy of a family’s insurance, and the stability of child’s health care needs significantly contributed to predicting his or her receipt of family-centered care. Further results suggested a relationship between receipt of family-centered care and the perception of challenge for these families; families receiving family-centered care perceive fewer challenges and feel less unmet need for child health services.
Value
Family-centered professionals provide critical voices in the development of policies and programs geared toward improving the health outcomes of children with ASD and their families.
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Purpose – This chapter will discuss how the positional self and prior experiences can influence the emotional self within the research journey, for example, being a sibling and…
Abstract
Purpose – This chapter will discuss how the positional self and prior experiences can influence the emotional self within the research journey, for example, being a sibling and losing a sibling. It explores the researcher’s emotional experience when working with children and their families, with a specific focus on the influence of the researcher presence and the sibling equilibrium.
Methodology/Approach – The chapter draws on the dramaturgical social interactions encountered in qualitative research which explored the experiences of siblings living in the context of cystic fibrosis. The study uses narrative inquiry and creative participatory methods to elicit sibling stories and provides insight into their worlds.
Findings – The chapter reflects on specific situations encountered on entering, engaging in and leaving the field, which had a significant emotional impact. Two sibling vignettes will be presented along with a discussion of how reflective metaphorical expression can be applied as a method of processing and coping with the research context.
Originality/Value – The chapter argues that the positional self and prior experiences can influence the emotional self within the research journey, and that reflective metaphorical expression can be used as a strategy to process thoughts and gain greater understanding of a situation as well as to provide an emotional release for the researcher. It also suggests that conducting research over a longer time period, as opposed to one visit, can be beneficial in terms of participant and researcher emotional transition.
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The purpose of this paper is to develop a multi-material topology optimization method for permanent magnet-assisted synchronous reluctance motors.
Abstract
Purpose
The purpose of this paper is to develop a multi-material topology optimization method for permanent magnet-assisted synchronous reluctance motors.
Design/methodology/approach
In the proposed method, the optimization procedure consists of two steps. In the first step, the entire rotor area was selected for the design region and the distribution of the core and air materials was optimized. In the second step, the design region was limited to the air region of the former solution and the distribution of magnets and cores or magnets and air was optimized.
Findings
Because of the two-step process of the proposed method, the design parameters can be reduced compared to the conventional method. As a result, this study can prevent the solution space from becoming more complex and superior solutions can be founded effectively.
Research limitations/implications
Since limited case study is denoted in this paper, much more case studies, for example, three-dimensional optimization problems, are needed to be discussed.
Practical implications
The optimal solutions obtained by the proposed method have a smaller magnet volume and higher average torque than that of the conventional method.
Originality/value
In the proposed methods, optimization methodology, which consists of two-steps process, is differed from the conventional method.
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James A. Dalton and Louis Esposito
John McGee's 1958 paper, “Predatory Price Cutting: The Standard Oil (NJ) Case,” has had an astonishing influence on both antitrust policy in the United States and economic lore…
Abstract
John McGee's 1958 paper, “Predatory Price Cutting: The Standard Oil (NJ) Case,” has had an astonishing influence on both antitrust policy in the United States and economic lore. McGee argued that predatory pricing is irrational and his analysis of the Standard Oil Company Matter, decided in 1911, led him to conclude that the Record in this case does not show that Standard Oil engaged in predatory pricing. This single publication appears to serve as a foundation of the U.S. Supreme Court's position on the issue of predatory pricing, as well as the assertion by many economists that predatory pricing is irrational and rarely occurs.
Numerous arguments have been advanced during the past 25 years that predatory pricing can be a rational strategy. As to McGee's empirical findings, there has been no re-examination of the Record of the Standard Oil case to determine the validity of his finding that the trial “Record” does not support the claim that Standard Oil engaged in predatory pricing.
We examined this Record and have found that the trial Record contains considerable evidence of predatory pricing by Standard Oil. Therefore, the Record does not support McGee's conclusion that Standard Oil did not engage in predatory pricing.
Thus, the decisions of the Supreme Court in recent years, as well as the opinions of many economists, concerning predatory pricing are not consistent with either current theory or the empirical record.
Hoejin Kim, Yirong Lin and Tzu-Liang Bill Tseng
The usage of additive manufacturing (AM) technology in industries has reached up to 50 per cent as prototype or end-product. However, for AM products to be directly used as final…
Abstract
Purpose
The usage of additive manufacturing (AM) technology in industries has reached up to 50 per cent as prototype or end-product. However, for AM products to be directly used as final products, AM product should be produced through advanced quality control process, which has a capability to be able to prove and reach their desire repeatability, reproducibility, reliability and preciseness. Therefore, there is a need to review quality-related research in terms of AM technology and guide AM industry in the future direction of AM development.
Design/methodology/approach
This paper overviews research progress regarding the QC in AM technology. The focus of the study is on manufacturing quality issues and needs that are to be developed and optimized, and further suggests ideas and directions toward the quality improvement for future AM technology. This paper is organized as follows. Section 2 starts by conducting a comprehensive review of the literature studies on progress of quality control, issues and challenges regarding quality improvement in seven different AM techniques. Next, Section 3 provides classification of the research findings, and lastly, Section 4 discusses the challenges and future trends.
Findings
This paper presents a review on quality control in seven different techniques in AM technology and provides detailed discussions in each quality process stage. Most of the AM techniques have a trend using in-situ sensors and cameras to acquire process data for real-time monitoring and quality analysis. Procedures such as extrusion-based processes (EBP) have further advanced in data analytics and predictive algorithms-based research regarding mechanical properties and optimal printing parameters. Moreover, compared to others, the material jetting progresses technique has advanced in a system integrated with closed-feedback loop, machine vision and image processing to minimize quality issues during printing process.
Research limitations/implications
This paper is limited to reviewing of only seven techniques of AM technology, which includes photopolymer vat processes, material jetting processes, binder jetting processes, extrusion-based processes, powder bed fusion processes, directed energy deposition processes and sheet lamination processes. This paper would impact on the improvement of quality control in AM industries such as industrial, automotive, medical, aerospace and military production.
Originality/value
Additive manufacturing technology, in terms of quality control has yet to be reviewed.
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Joy Walker, Jackie Green and Sylvia Tilford
The provision of appropriate sex education for teachers has been identified as a key factor in improving the quality of sex and relationship education (SRE). This paper focuses on…
Abstract
The provision of appropriate sex education for teachers has been identified as a key factor in improving the quality of sex and relationship education (SRE). This paper focuses on evaluating a sexual health training programme designed to prepare school teams to deliver high quality SRE. The evaluation followed up three schools prospectively and 11 schools retrospectively. Multiple methods were used to gather and triangulate qualitative and quantitative data from teachers, senior management, pupils and trainers. The training programme was found to have made positive contributions to SRE programme and policy development through building schools’ capacity to be responsive to young people’s needs, team building, personal and professional development, and greater collaboration in school between health and education services, parents and pupils. In the light of the findings, recommendations are made to guide future training.