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1 – 10 of 234
Article
Publication date: 1 August 2000

D.M. Stubbs, S.H. Pulko, A.J. Wilkinson, B. Wilson, F. Christiaens and K. Allaert

The embedding of passive components such as resistors, capacitors and inductors within printed circuit boards (PCBs) is motivated, to a large extent, by the desire for…

Abstract

The embedding of passive components such as resistors, capacitors and inductors within printed circuit boards (PCBs) is motivated, to a large extent, by the desire for increased miniaturisation of electronic goods. However, resistors and, to a lesser extent, inductors are heat generating devices, and the temperature developed within PCBs as the result of the operation of embedded passives is a significant aspect of the design of a multilayer PCB. Here we investigate, by simulation, temperature fields associated with operation of embedded resistors. It is shown that for board dimensions less than 2cm × 2cm temperatures achieved are higher than those associated with larger boards having identical structures and identical resistor heat generation. Detailed simulations are used to investigate the sensitivity of the temperature rises associated with embedded resistors to copper track coverage and to thermal coupling of the PCB to ambient on its upper and lower surfaces. The implications of these findings are discussed both in the context of the design of real PCBs and in the context of thermal simulation.

Details

Microelectronics International, vol. 17 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 February 2022

Yangyang Lai, Ke Pan, Yuqiao Cen, Junbo Yang, Chongyang Cai, Pengcheng Yin and Seungbae Park

This paper aims to provide the proper preset temperatures of the convection reflow oven when reflowing a printed circuit board (PCB) assembly with varied sizes of…

178

Abstract

Purpose

This paper aims to provide the proper preset temperatures of the convection reflow oven when reflowing a printed circuit board (PCB) assembly with varied sizes of components simultaneously.

Design/methodology/approach

In this study, computational fluid dynamics modeling is used to simulate the reflow soldering process. The training data provided to the machine learning (ML) model is generated from a programmed system based on the physics model. Support vector regression and an artificial neural network are used to validate the accuracy of ML models.

Findings

Integrated physical and ML models synergistically can accurately predict reflow profiles of solder joints and alleviate the expense of repeated trials. Using this system, the reflow oven temperature settings to achieve the desired reflow profile can be obtained at substantially reduced computation cost.

Practical implications

The prediction of the reflow profile subjected to varied temperature settings of the reflow oven is beneficial to process engineers when reflowing bulky components. The study of reflowing a new PCB assembly can be started at the early stage of board design with no need for a physical profiling board prototype.

Originality/value

This study provides a smart solution to determine the optimal preset temperatures of the reflow oven, which is usually relied on experience. The hybrid physics–ML model providing accurate prediction with the significantly reduced expense is used in this application for the first time.

Article
Publication date: 11 April 2022

Yaojie Zheng, Huili Sun, Luchun Yan, Huisheng Yang, Kewei Gao, Xiaolu Pang and Alex A. Volinsky

The purpose of this study is to investigate the effect of ferrite on hydrogen embrittlement (HE) of the 17-4PH stainless steels.

Abstract

Purpose

The purpose of this study is to investigate the effect of ferrite on hydrogen embrittlement (HE) of the 17-4PH stainless steels.

Design/methodology/approach

The effects of ferrite on HE of the 17-4PH stainless steels were investigated by observing microstructure and conducting slow-strain-rate tensile tests and hydrogen permeability tests.

Findings

The microstructure of the ferrite-bearing sample is lath martensite and banded ferrite, and the ferrite-free sample is lath martensite. After hydrogen charging, the plasticity of the two steels is significantly reduced, along with the tensile strength of the ferrite-free sample. The HE susceptibility of the ferrite-bearing sample is significantly lower than the ferrite-free steel, and the primary fracture modes gradually evolved from typical dimple to quasi-cleavage and intergranular cracking. After aging at 480°C for 4 h and hydrogen charging for 12 h, the 40.9% HE susceptibility of ferrite-bearing samples was the lowest. In addition, the hydrogen permeation tests show that ferrite is a fast diffusion channel for hydrogen, and the ferrite-bearing samples have higher effective hydrogen diffusivity and lower hydrogen concentration.

Originality/value

There are a few studies of the ferrite effect on the HE properties of martensitic precipitation hardening stainless steel.

Details

Anti-Corrosion Methods and Materials, vol. 69 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

Content available
Article
Publication date: 1 December 2002

176

Abstract

Details

Microelectronics International, vol. 19 no. 3
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 December 1999

Bart Vandevelde and Eric Beyne

Presents the thermo‐mechanical modelling of a new type of area array package: the flip chip on polymer stud grid array (PSGA). The objective is to optimise the material…

Abstract

Presents the thermo‐mechanical modelling of a new type of area array package: the flip chip on polymer stud grid array (PSGA). The objective is to optimise the material and geometrical design of this PSGA package and the flip chip assembly in order to achieve the highest thermal fatigue reliability for the solder joints in this structure. A parameterised non‐linear finite element model is used to calculate the inelastic strains induced in the solder joints due to thermal cycling. The techniques of design of experiments (DOE) and response surface modelling (RSM) enhance the parameter sensitivity analysis and optimisation of the PSGA design. After the optimisation of the structure, a very high solder joint fatigue reliability of this flip chip to PSGA package has been achieved.

Details

Microelectronics International, vol. 16 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 28 May 2021

Changpu Ma and Binghai Zhou

The use of multiple-capacity rail-guided vehicles (RGVs) has made automated storage and retrieval system (AS/RS) optimization more complex. The paper performs dual-RGV…

252

Abstract

Purpose

The use of multiple-capacity rail-guided vehicles (RGVs) has made automated storage and retrieval system (AS/RS) optimization more complex. The paper performs dual-RGV scheduling considering loading/unloading and collision-avoidance constraints simultaneously as these issues have only been considered separately in the previous literature.

Design/methodology/approach

This paper proposes a novel model for dual-RGV scheduling with two-sided loading/unloading operations and collision-avoidance constraints. To solve the proposed problem, a hybrid harmony search algorithm (HHSA) is developed. To enhance its performance, a descent-based local search with eight move operators is introduced.

Findings

A group of problem instances at different scales are optimized with the proposed algorithm and the results are compared with those of two other high-performance methods. The results demonstrate that the proposed method can efficiently solve realistically sized cases of dual multi-capacity RGV scheduling problems in AS/RSs.

Originality/value

For the first time in the research on dual multi-capacity RGV scheduling in an AS/RS, two-sided loading/unloading operations and collision avoidance constraints are simultaneously considered. Furthermore, a mathematical model for minimizing the makespan is developed and the HHSA is developed to determine solutions.

Article
Publication date: 29 November 2019

Manish Kumar Ghodki, Akhilesh Swarup and Yash Pal

The purpose of this paper is to design and develop an IR and sprinkler based embedded controller operated robotic arm for automatic dust removal system to mitigate the…

Abstract

Purpose

The purpose of this paper is to design and develop an IR and sprinkler based embedded controller operated robotic arm for automatic dust removal system to mitigate the dust effect on the solar panel surface, since dust accumulation normally affected by real weather conditions is one of the serious concern for the deterioration of photovoltaic (PV) system output.

Design/methodology/approach

The system is a wet cleaning device which provides a cheap silicon rubber-based wiping operation controlled by the pulse width modulation-operated motors of robotic arm. The IEEE 1149.1-compliant mixed signal-embedded platform of C8051F226DK is involved to command the complete system.

Findings

A prototype of 30 WP system is capable of producing an inspiring average value of 11.26 per cent in energy increase, 13.63 per cent in PV module efficiency and 85.20 per cent in performance ratio of the system after 73 days of cleaning in summer season. In addition, a total of 1,617.93 W power; 1,0516.55 Wh energy; and 350.55 KWh/KWP final yield was found during the entire cleaning period.

Originality/value

A novel technique of the implementation of IR sensor and sprinkler in dust mitigation is proposed in this paper. The IR sensor is used as a versatile object which can manage the robotic arm setting and control the automatic switching between cleaning and charging, as well as identify the thermal condition of solar panel for overheating.

Details

Journal of Engineering, Design and Technology , vol. 18 no. 4
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 9 February 2022

Jean-marc Linares, Julien Chaves-Jacob, Quentin Lopez and Jean-Michel Sprauel

The mechanical characterization of selective laser melting (SLM) parts is an industrial challenge. This paper aims to propose a methodology to control the fatigue life of…

Abstract

Purpose

The mechanical characterization of selective laser melting (SLM) parts is an industrial challenge. This paper aims to propose a methodology to control the fatigue life of 17-4Ph stainless steel by selecting the most relevant manufacturing parameters: i.e. laser power, laser travel speed, hatch spacing and laser defocusing.

Design/methodology/approach

A rough and refined design of experiment (DOE) is carried out to target the best combination of process parameters. A response surface model is then constructed to predict the parameter combination that optimizes the fatigue performance.

Findings

This study results show that the fatigue limit of the specimens manufactured by SLM (471.7 MPa at 107 cycles) has reached near 90% of the value found in samples machined from a bar. This demonstrates the applicability of the method proposed to optimize the SLM process and control the fatigue life of 17-4Ph stainless steel. The study results are compared with other research works and provide an increase of 18% to the fatigue limit.

Originality/value

This study showcases a DOE methodology to optimize the SLM parameters to achieve fatigue performance as great as that of solid 17-4Ph stainless steel.

Details

Rapid Prototyping Journal, vol. 28 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Open Access
Article
Publication date: 5 December 2022

Giuseppe Nicolò, Diana Ferullo, Natalia Aversano and Nadia Ardito

The present study aims to extend the knowledge of intellectual capital disclosure (ICD) disclosure practices in the Italian Healthcare Organisations (HCOs) context. The…

Abstract

Purpose

The present study aims to extend the knowledge of intellectual capital disclosure (ICD) disclosure practices in the Italian Healthcare Organisations (HCOs) context. The ultimate goal of the study is to provide fresh insight into the possible explanatory factors that may drive the extent of ICD provided by Italian HCOs via the web.

Design/methodology/approach

The present study applies a manual content analysis on the websites of a sample of 158 HCOs to determine the level of voluntary ICD. A multivariate regression model is estimated to test the association between different variables – size, gender diversity in top governance positions, financial performance and indebtedness – and the level of ICD provided by sampled HCOs through their official websites.

Findings

Content analysis results reveal that – in the absence of mandatory requirements – Italian HCOs tend to use websites to disclose information about IC. Particular attention is devoted to Structural and Relational Capital. The statistical analysis pinpoints that size and indebtedness negatively influence the level of ICD. In contrast, the presence of a female General Manager (GM) positively drives ICD. Also, it is observed that Research and University HCOs and those located in the Italian Northern Regions are particularly prone to discharge accountability on IC through websites.

Originality/value

To the best of the authors’ knowledge, this is the first study that examines voluntary ICD practices through websites in the Italian HCOs' context. Also, since prior studies on IC in the healthcare context are mainly descriptive or normative, this is the first study examining the potential determinants of ICD provided by HCOs in terms of size, gender diversity in top governance positions, financial performance and indebtedness.

Details

International Journal of Public Sector Management, vol. 36 no. 1
Type: Research Article
ISSN: 0951-3558

Keywords

Article
Publication date: 6 May 2022

Paola Paoloni, Giuseppe Modaffari, Federica Ricci and Gaetano Della Corte

In the past decade, intellectual capital (IC) measurement and reporting have been feeding scientific debate; however, only few studies address these issues together. The…

Abstract

Purpose

In the past decade, intellectual capital (IC) measurement and reporting have been feeding scientific debate; however, only few studies address these issues together. The present research aims to provide an integrated view of the topics covered by the existing literature and to highlight the emerging research trends and set the agenda for future research.

Design/methodology/approach

This study develops a structured literature review (SLR) of the extant research concerned with IC measurement and reporting, using a comprehensive sample of 1,021 articles extracted from the Scopus database.

Findings

The findings of the SLR show that the existing literature focuses on seven research areas: IC and public sector; IC university and education; IC evaluation method; internal and external IC disclosure; IC and CSR; management of IC in organizations; other. Overall, findings indicate that IC measurement and reporting are highly researched topics that continue to attract the interests of scholars. Finally, the SLR analysis has allowed outlining a future research agenda, with particular reference to the IC evaluation method and internal and external IC disclosure research areas.

Research limitations/implications

The main limitation of this research lies in the manual screening of relevant studies, which entails some degree of subjectivity. Furthermore, another limitation research could be considered the use of a single database (Scopus).

Originality/value

The present study brings potential contributions for scholars and practitioners. From a scholarly perspective, the paper provides a systematization of scientific contributions that have dealt with IC measurement and reporting. In particular, it contributes to the scholarly debate bringing into focus various IC measurement and reporting issues in the landscape of private and public organizations. Referring to practical implications, our research supports the strategic use of IC measurement and reporting as a key lever for improving the management of firms. Using an analytical framework that combines insights from the agency, stakeholder and legitimacy theories, this study highlights that IC reporting activity should be used strategically as a means to engage with all firm's stakeholders, in particular with a view to reducing information asymmetry and improving firm reputation.

Details

Journal of Intellectual Capital, vol. 24 no. 1
Type: Research Article
ISSN: 1469-1930

Keywords

1 – 10 of 234