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There are few reports that evolutional topology optimization methods are applied to the conductor geometry design problems. This paper aims to propose an evolutional topology optimization method is applied to the conductor design problems of an on-chip inductor model.

This paper presents a topology optimization method for conductor shape designs. This method is based on the normalized Gaussian network-based evolutional on/off topology optimization method and the covariance matrix adaptation evolution strategy. As a target device, an on-chip planer inductor is used, and single- and multi-objective optimization problems are defined. These optimization problems are solved by the proposed method.

Through the single- and multi-objective optimizations of the on-chip inductor, it is shown that the conductor shapes of the inductor can be optimized based on the proposed methods.

The proposed topology optimization method is applicable to the conductor design problems in that the connectivity of the shapes is strongly required.

The purpose of this paper is to illustrate the new technical demands and reliability challenges to printed circuit board (PCB) designs, materials and processes when the transmission frequency increases from Sub-6 GHz in previous generations to millimeter (mm) wave in fifth-generation (5G) communication technology.

The approach involves theoretical analysis and actual case study by various characterization techniques, such as a stereo microscope, metallographic microscope, scanning electron microscope, energy dispersive spectroscopy, focused ion beam, high-frequency structure simulator, stripline resonator and mechanical test.

To meet PCB signal integrity demands in mm-wave frequency bands, the improving proposals on copper profile, resin system, reinforcement fabric, filler, electromagnetic interference-reducing design, transmission line as well as via layout, surface treatment, drilling, desmear, laminating and electroplating were discussed. And the failure causes and effects of typical reliability issues, including complex permittivity fluctuation at different frequencies or environments, weakening of peel strength, conductive anodic filament, crack on microvias, the effect of solder joint void on signal transmission performance and soldering anomalies at ball grid array location on high-speed PCBs, were demonstrated.

The PCB reliability problem is the leading factor to cause failures of PCB assemblies concluded from statistical results on the failure cases sent to our laboratory. The PCB reliability level is very essential to guarantee the reliability of the entire equipment. In this paper, the summarized technical demands and reliability issues that are rarely reported in existing articles were discussed systematically with new perspectives, which will be very critical to identify potential reliability risks for PCB in 5G mm-wave applications and implement targeted improvements.

With the recent increasing relevance of sustainability, multinational enterprises are faced with divergent stakeholder demands and persistently shifting priorities. This study aims to examine stakeholders’ perceptions of the sustainability performance of a gold mining subsidiary in Ghana.

Using a purposive sampling technique, the authors interviewed managers and employees of the case enterprise, officials of regulatory institutions and host community members on their perceptions of the case enterprise’s sustainability performance. The authors triangulated the opinions expressed by these stakeholders with data from annual reports. The data were analysed through the lens of stakeholder theory.

The authors found that while members of the host community and the regulatory institutions were keenly interested in the case enterprise’s social and environmental activities, they perceived their performance as unimpressive, considering the economic benefits derived from the mining operations. On the contrary, the managers and employees of the case enterprise were satisfied with their environmental compliance and social intervention programmes, even though the company’s economic position had declined. The authors submit that the variations in the sustainability performance perceptions among the stakeholders are due to the lack of a deeper understanding of the other stakeholders’ expectations.

To equitably satisfy diverse stakeholder expectations, the study highlights the role of stakeholder collaborations in understanding the expectations of more salient stakeholder groups such as community members and employees, as well as the lesser salient groups such as academics. It also demonstrates the fluidity of sustainability and its benefits in designing a consensual sustainable management strategy. This implies that managers of the case mining enterprise make the necessary efforts to meet the diverse stakeholder needs while attaining their primary objective of creating wealth for shareholders.

Compared to advanced economies, studies on sustainability performance in emerging economies are limited. Nonetheless, these limited studies leave out stakeholder perceptions, focusing more on quantitative performance indicators. Using thematic and content analyses, the authors investigate stakeholder perceptions on the sustainability performance of a case mining subsidiary operating in Ghana. The study focused on Ghana because it is ranked with South Africa as the top two producers of gold in Africa. Nonetheless, unlike South Africa, Ghana faces more sustainability challenges from the mining sector due to weak institutions in enforcing sustainability standards.

The purpose of this paper is to investigate the impact of mechanical vibration on the heat transfer and pressure drop characteristics of semicircular channel printed circuit heat exchangers (PCHEs), while also establishing correlations between vibration parameters and thermal performance.

By combining experimental and numerical simulation methods, the heat transfer coefficient and pressure drop characteristics of supercritical carbon dioxide (S-CO₂) in a semicircular channel with a diameter of 2 mm under vibration conditions were studied. Reinforce the research by conducting computational fluid dynamics studies using ANSYS Fluent 22.0, the experimental results were compared with the numerical simulation results to verify the accuracy of the numerical method.

The use of vibration has the potential to attenuate the degradation of wall heat transfer caused by buoyancy-induced PCHEs on the upward-facing surface. The heat transfer enhancement (HTE) was maximized by an increase of 18.2%, while the pressure drop enhancement (PDE) was elevated by over 25-fold. The capacity to enhance the heat exchange between S-CO₂ and channel walls through increasing vibration intensity is limited, indicating maximum effectiveness in improving thermal performance.

Conducting heat transfer experiments on PCHEs with mechanical vibration enhancement and verifying the accuracy of the vibration numerical model. The relation based on the dimensionless factor is derived. To provide theoretical support for using vibration to enhance the heat transfer capability of PCHEs.