Fang Liu, Zhongwei Duan, Runze Gong, Jiacheng Zhou, Zhi Wu and Nu Yan
Ball grid array (BGA) package is prone to failure issues in a thermal vibration-coupled environment, such as deformation and fracture of solder joints. To predict the minimum…
Abstract
Purpose
Ball grid array (BGA) package is prone to failure issues in a thermal vibration-coupled environment, such as deformation and fracture of solder joints. To predict the minimum equivalent stress of solder joints more accurately and optimize the solder joint structure, this paper aims to compare the machine learning method with response surface methodology (RSM).
Design/methodology/approach
This paper introduced a machine learning algorithm using Grey Wolf Optimization (GWO) Support Vector Regression (SVR) to optimize solder joint parameters. The solder joint height, spacing, solder pad diameter and thickness were the design variables, and minimizing the equivalent stress of solder joint was the optimization objective. The three dimensional finite element model of the printed circuit board assembly was verified by a modal experiment, and simulations were conducted for 25 groups of models with different parameter combinations. The simulation results were employed to train GWO-SVR to build a mathematical model and were analyzed using RSM to obtain a regression equation. Finally, GWO optimized these two methods.
Findings
The results show that the optimization results of GWO-SVR are closer to the simulation results than those of RSM. The minimum equivalent stress is decreased by 8.528% that of the original solution.
Originality/value
This study demonstrates that GWO-SVR is more precise and effective than RSM in optimizing the design of solder joints.
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Yong Rong Chan, Sankaranarayanan Seetharaman, Jerry Y.H. Fuh and Heow Pueh Lee
This study aims to assess the feasibility of laser powder bed fusion (LPBF) processing using as-received gas-atomized spherical Neodymium-Iron-Boron (NdFeB) powder (17–68 µm)…
Abstract
Purpose
This study aims to assess the feasibility of laser powder bed fusion (LPBF) processing using as-received gas-atomized spherical Neodymium-Iron-Boron (NdFeB) powder (17–68 µm), compared to literature methods that sieve to a narrow size range (<40 µm).
Design/methodology/approach
The research involves single track and layer printing, process optimization and subsequent heat treatment and magnetic annealing. The experimental approach includes conducting systematic printing trials to assess the impact of various parameters on printed track and layer quality, and refining printing parameters through iterative testing. Heat treatment and magnetic annealing are applied to achieve the desired magnetic properties.
Findings
A minimum linear energy density of 0.10 J/mm is required for continuous track formation, with track width largely unaffected by varying linear energy densities. An optimal hatch spacing of approximately 42% overlap avoids layer defects, with 0.10 mm spacing suitable for layer thicknesses between 30 and 80 µm. A stable processing window for energy density (EA) of 0.6–1.0 J/mm2 was identified, allowing cuboid printing despite some discontinuous tracks, indicating potential fusion issues. Maximizing volumetric energy density (EV) within this range correlates positively with part density, achieving 92% density, coercivity of 490 kA/m and remanence of 496 mT. Post-treatment, density increased to 96%, coercivity to 582 kA/m and remanence to 544 mT.
Originality/value
This study fills a significant gap in LPBF literature for NdFeB by using the original wider size range of spherical powder without sieving, demonstrating improved cost-effectiveness, material efficiency and build efficiency. These findings offer practical recommendations for addressing the challenges related to LPBF processing of NdFeB powder.
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Shiang-Wuu Perng, Horng Wen Wu, Yi-Ling Guo and Tao-Hsuan Liu
The purpose of this study is to value the thermal and hydraulic transport augmentation of turbulent fluid flow within the round-pipe axis fixed by a twisted-staggered…
Abstract
Purpose
The purpose of this study is to value the thermal and hydraulic transport augmentation of turbulent fluid flow within the round-pipe axis fixed by a twisted-staggered concave/convex dimples tape.
Design/methodology/approach
This study meets the report’s novel design by axis-inserting a twisted plastic tape with staggered concave/convex dimples of varying diameters (4 and 6 mm) and depths (1, 1.4 and 1.8 mm). Introducing a realizable model integrated with an improved wall function and SIMPLE solving procedure evaluates the thermo-hydraulic transport as Reynolds number is feasible as 5,000, 10,000, 15,000 and 20,000. In addition, using the findings from the present experimental work validates the numerical methodology.
Findings
This paper reveals that the staggered concave/convex dimples on the axis-fixed plastic tape can significantly improve thermo-hydraulic transport within this outer-heated tube. Furthermore, the processed dimples can cause flow disturbance, which increases turbulent kinetic energy and accelerates fluid mixing around a twisted plastic tape, resulting in enhanced thermal convection. The six kinds of twisted tapes (C1−C6) result in the thermo-hydraulic performance index (η) of 1.18–1.32 at Re = 5000. Among all the cases, the dimples using 4 mm combined with 6 mm diameter and 1.4 mm height (C4) earn the highest, around 1.40 at Re = 5,000.
Research limitations/implications
The conditions of constant hydraulic-thermal characteristics of working fluid (air), steady Newtonian fluid considered, and the ignored radiative heat transfer and gravity are the research limitations of the numerical simulation.
Practical implications
The given results can benefit from a round tube design of a thermal apparatus axis fixed by a twisted-staggered concave/convex dimples tape to augment the thermo-hydraulic transport.
Originality/value
Staggered concave/convex dimples on the surface of a twisted tape allow for impinging and swirling flow along the tape. These processed dimples can induce flow disturbance, which increases the turbulent kinetic energy and facilitates fluid mixing in a twisted tape. Furthermore, the hybrid-diameter dimples have enough flow channels for fluid separation-reattachment, and the thermo-hydraulic performance index has improved. This paper then presents a helpful passive approach for cooling a thermal device.
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Ali Akbar Abbasian Arani and Ali Memarzadeh
Using passive techniques like twisted tapes and corrugated surface is an efficient method of heat transfer improvement, since the referred manners break the boundary layer and…
Abstract
Purpose
Using passive techniques like twisted tapes and corrugated surface is an efficient method of heat transfer improvement, since the referred manners break the boundary layer and improve the heat exchange. This paper aims to present an improved dual-flow parabolic trough collector (PTC). For this purpose, the effect of an absorber roof, a type of turbulator and a grooved absorber tube in the presence of nanofluid is investigated separately and simultaneously.
Design/methodology/approach
The FLUENT was used for solution of governing equation using control volume scheme. The control volume scheme has been used for solving the governing equations using the finite volume method. The standard k–e turbulence model has been chosen.
Findings
Fluid flow and heat transfer features, as friction factor, performance evaluation criteria (PEC) and Nusselt number have been calculated and analyzed. It is showed that absorber roof intensifies the heat transfer ratio in PTCs. Also, the combination of inserting the turbulator, outer corrugated and inner grooved absorber tube surface can enhance the PEC of PTCs considerably.
Originality/value
Results of the current study show that the PTC with two heat transfer fluids, outer and inner surface corrugated absorber tube, inserting the twisted tape and absorber roof have the maximum Nusselt number ratio equal to 5, and PEC higher than 2.5 between all proposed arrangements for investigated Reynolds numbers (from 10,000 to 20,000) and nanoparticles [Boehmite alumina (“λ-AlOOH)”] volume fractions (from 0.005 to 0.03). Maximum Nusselt number and PEC correspond to nanoparticle volume fraction and Reynolds number equal to 0.03 and 20,000, respectively. Besides, it was found that the performance evaluation criteria index values continuously grow by an intensification of nanoparticle volume concentrations.
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Tunahan Gunay, Duygu Erdem and Ahmet Ziyaettin Sahin
High surface area-to-volume ratios make nanoparticles ideal for cancer heat therapy and targeted medication delivery. Moreover, ternary nanofluids (TNFs) may possess superior…
Abstract
Purpose
High surface area-to-volume ratios make nanoparticles ideal for cancer heat therapy and targeted medication delivery. Moreover, ternary nanofluids (TNFs) may possess superior thermophysical properties compared to mono- and hybrid nanofluids due to their synergistic effects. In light of this information, the objective of this article is to examine the blood-based TNF flow within convergent/divergent channels under velocity slip and temperature jump.
Design/methodology/approach
Leading partial differential equations corresponding to the problem are transformed into a system of nonlinear ordinary differential equations by using similarity variables. The bvp4c code that uses the finite difference method is used to obtain a numerical solution.
Findings
The effect of nanoparticles may change depending on the characteristics of flow near the wall. The properties and proportions of the used nanoparticles become important to control the flow. When TNF was used, an increase in the Nusselt number between 4.75% and 6.10% was observed at low Reynolds numbers. At high Reynolds numbers, nanoparticles reduce the Nusselt number and skin friction coefficient values under some special flow conditions. Importantly, the effects of second-order slip on engineering parameters were also investigated. Furthermore, the Nusselt number increases with increasing shape factor.
Research limitations/implications
Obtained results of the study can be beneficial in both nature and engineering, especially blood flow in veins.
Originality/value
The main innovations of this study are the usage of blood-based TNF and the examination of the effect of shape factor in convergent/divergent channels with second-order velocity slip.
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Muhammad Imran Khan, Muhammad Farooq, Qadri Al Jabri, Saif Ullah and Mazhar Hussain
A company’s dividend policy is determined not just by its strategy but also by the qualities of its managers, particularly overconfidence. As a result, the purpose of this study…
Abstract
Purpose
A company’s dividend policy is determined not just by its strategy but also by the qualities of its managers, particularly overconfidence. As a result, the purpose of this study is to explore the impact of CEO overconfidence on dividend policy using the dividend payout ratio and dividend yield ratio.
Design/methodology/approach
The study’s sample includes 170 non-financial enterprises listed on the Pakistan Stock Exchange between 2011 and 2022. Furthermore, we used corporate governance and firm-specific factors as control variables. The fixed effect model based on the Hausman test result and dynamic system GMM estimation technique was employed in the analysis. Furthermore, the dividend dummy variable and alternative proxies of dividend payments are used to ensure the results are robust.
Findings
The findings indicate that CEOs’ overconfidence positively impacts dividend payout and dividend yield ratios. Further analysis reveals that board size and remuneration committee significantly impact dividend payment among corporate governance control variables, while block holding has a negative effect. Among firm-specific control variables, the results suggest that firm size, profitability, and market-to-book ratio are significantly positively associated. In contrast, the coefficient of variation and debt ratio are inversely associated with dividend payments.
Practical implications
Managerial overconfidence benefits shareholders by increasing dividend payouts, but firms may struggle in the long run if they do not have adequate retained earnings to meet capital requirements. Dividends and retained earnings must be balanced to make enough funds available for long-term investment in capital-intensive projects.
Originality/value
Although little previous research has focused on the managerial overconfidence-dividend policy relationship, the authors believe this is the first study to test this relationship generally in emerging markets, particularly Pakistan.
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Abstract
Purpose
This study aims to design a novel seasonal discrete grey model for forecasting monthly natural gas consumption by incorporating damping accumulation and time-polynomial term.
Design/methodology/approach
Considering the principle of new information priority and nonlinear patterns in the original series of monthly natural gas consumption, we establish a novel discrete seasonal grey model by adding the damping accumulation and time-polynomial term into the existing model. In addition, the order of damping accumulation and the coefficient of time-power term can be determined by the moth flame optimization (MFO) algorithm.
Findings
The empirical cases show that the proposed model has a better prediction performance when compared with other benchmark models, including six seasonal grey models, one statistical model and one artificial intelligent model. Based on forecasts, the proposed model can be considered a promising tool for monthly natural gas consumption (NGC) in US.
Originality/value
By combining the damping accumulation and the time-polynomial term, a new discrete seasonal grey model for improving the prediction performance of the existing grey model is proposed. The properties of the proposed model are given, and the newly-designed model is initially applied to predict monthly NGC in US.
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Putri Reno Kemala Sari, Rosyia Wardani, Galuh Ratna Mutia, Syaiful Amri and Ririrn Tri Ratnasari
This study aims to critically examine the multifaceted challenges, innovative solutions and strategic approaches required to successfully integrate halal tourism with Sasak…
Abstract
Purpose
This study aims to critically examine the multifaceted challenges, innovative solutions and strategic approaches required to successfully integrate halal tourism with Sasak cultural heritage in Setanggor Village. Adopting a comprehensive stakeholder perspective, it analyses insights from four key sectors: governmental bodies, local community members, academic institutions and industry practitioners. Through this multidimensional approach, the study aims to formulate an effective strategy for seamlessly blending traditional Sasak cultural elements with modern halal tourism practices.
Design/methodology/approach
The study uses the sophisticated analytical network process (ANP) methodology to systematically identify, evaluate and analyse the complex network of factors influencing Sasak cultural integration within Setanggor Village’s halal tourism framework. To ensure comprehensive data collection and robust analysis, a mixed-method approach combining quantitative and qualitative techniques is implemented. This includes structured questionnaires for systematic data gathering, focus group discussions for collective insights, in-depth interviews for detailed stakeholder perspectives and direct observational studies for real-world context understanding.
Findings
This conceptual investigation reveals significant research gaps in the current understanding of halal tourism development in Setanggor Village. The study presents a strategic framework that identifies and prioritises crucial elements necessary for successful integration. The findings highlight critical priorities that must be addressed to ensure the sustainable growth and long-term viability of halal tourism in the region while preserving authentic Sasak cultural values.
Practical implications
The research outcomes provide valuable insights and actionable recommendations for stakeholders in Setanggor Village, particularly those involved in strategic planning and policy development. The findings serve as a comprehensive reference for developing and implementing effective halal tourism initiatives that align with local community needs, cultural preservation goals and economic development objectives.
Social implications
The research demonstrates significant social implications by offering a sustainable tourism development model that preserves cultural heritage while promoting economic opportunities. By integrating Sasak cultural elements with halal tourism principles, the study provides a framework for community empowerment, enhanced social cohesion and economic diversification. The approach promotes cross-cultural understanding, creates employment opportunities for local communities and establishes a model for inclusive tourism development that respects traditional values while adapting to contemporary market needs.
Originality/value
This study uniquely contributes to the field by offering evidence-based, practical insights to guide decision-makers and industry practitioners in developing halal tourism strategies that effectively balance modern tourism requirements with traditional cultural preservation. It provides a blueprint for creating sustainable tourism models that respect, celebrate and integrate local cultural heritage.