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The purpose of this paper is to report on the flow past a porous square cylinder, implementing the stress jump treatments for the porous‐fluid interface.

The numerical method was developed for flows involving an interface between a homogenous fluid and a porous medium. It is based on the finite volume method with body‐fitted and multi‐block grids. The Brinkman‐Forcheimmer extended model was used to govern the flow in the porous medium region. At its interface, a shear stress jump that includes the inertial effect was imposed, together with a continuity of normal stress.

The present model is validated by comparing with those for the flow around a solid circular cylinder. Results for flow around porous square cylinder are presented with flow configurations for different Darcy number, 10⁻² to 10⁻⁵, porosity from 0.4 to 0.8, and Reynolds number 20 to 250. The flow develops from steady to unsteady periodic vortex shedding state. It was found that the stress jump interface condition can cause flow instability. The first coefficient β has a more noticeable effect whereas the second coefficient β₁ has very small effect, even for Re=200. The effects of the porosity, Darcy number, and Reynolds number on lift and drag coefficients, and the length of circulation zone or shedding period are studied.

The present study implements the numerical method based on finite volume method with a collocated variable arrangement to treat the stress jump condition.

Two time metaphors are often adopted to express the passage of time: the ego-moving metaphor that conceptualizes the ego as moving toward the stationary event (e.g. we are approaching the holiday) or the event-moving metaphor that conceptualizes the event as moving toward the stationary ego (e.g. the holiday is approaching us). This paper aims to investigate the influence of the time metaphor on regulatory focus, as well as its downstream marketing implications.

Five studies were conducted. Studies 1a–1c examined the moderating effect of the valence of events on the relationship between time metaphors and regulatory focus. Studies 2–3 investigated the downstream marketing implications of the above effects.

The findings indicated that compared to the event-moving metaphor, the ego-moving metaphor is more likely to evoke a promotion focus when consumers anticipate a positive event. However, when the event is negative, the ego-moving metaphor is more likely to evoke a prevention focus compared to the event-moving metaphor.

This research extends the previous literature on regulatory focus activation by showing that time metaphors affect regulatory focus, and that event valence plays a critical moderating role in the relationship.

Many companies rely on positive events (e.g. holidays, anniversaries) to market their products. The findings of this research suggest that companies promoting products with promotion-related benefits or products with higher risks should adopt an ego-moving metaphor to describe the coming of the event. In contrast, companies promoting products with prevention-related benefits or products with low risks should adopt an event-moving metaphor to describe the coming of the event.

This research showed that the effects of time metaphors on consumers’ regulatory focus depend on the valence of the events. It also demonstrated the downstream implications of time metaphors by showing that time metaphors influence consumer product choices and financial decisions.

The rural revitalization is a significant indicator of social development in China. Despite the crucial role that local governments play in coordinating urban and rural development, rural areas continue to face limited investment opportunities and scholarship on the impact of local government competition on urban–rural income disparity is scant, especially lacking empirical research from the spatial perspective. The authors contribute to closing the knowledge gap by exploring the spatial spillover effect of local government competition using the sample of China.

This study evaluated the urban–rural income inequality using the Theil index and constructed the spatial Durbin model to analyze the data by the method of maximum likelihood estimation.

The findings from the Theil index showed that the income gap is significant between city and countryside in China, with being wider in the western region compared to the eastern region. The evidence from the spatial Durbin model revealed that, in the same province, local government competition widens this gap, while competition from neighboring regions prompts a reduction in this gap in this province.

The authors recommended some policy implications, such as supporting the development in underdeveloped regions and improving the promotion evaluation criteria for local officials.

This article is original in exploring the spatial effects of local government competition on the urban–rural income gap. In addition, instead of using a single proxy to measure the urban–rural income gap, in the current paper, the Theil index for evaluating the disparity is incorporated.

The peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-07-2023-0582

Adding Pd element to Au wire can improve the reliability of Au-Al bonding, but the mechanism of Pd element has not been well revealed so far. The purpose of this study is to reveal in more detail the mechanism of the role of Pd elements in Au/Al bonding.

In this paper, the microstructure changes and tensile data of 99.99% (4N) gold wire and 99% (2N) gold wire with 1 at % Pd were compared through high-temperature thermal aging treatment of the specimens, so as to explore the influence mechanism of Pd element on Au-Al bonding reliability.

The addition of Pd element effectively reduces the thickness of intermetallic compounds (IMCs) layer and strengthens the fracture tension and reliability. Compared with the 4N specimen, the average thickness of the IMCs layer of the 2N specimen under the same conditions is reduced by 1 µm, and the tensile value of the 2N specimen is increased by 1−3 g. Stored at 200°C for 200 h, the failure rate of bond point of 4N specimen reached 94.64%, and that of 2N specimen was 20%, with a difference of 4.73 times.

Through comparative analysis of the data, this study found that the doping of Pd element in Au-Al IMCs in the early stage slowed down the growth rate of the IMCs, and the precipitation of Pd element in the late stage to form a better Pd-rich layer hindered the element mutual diffusion behavior between Au and Al.

This paper aims to present a picture of the past and the present status of the Distance Education College (DEC) of East China Normal University (ECNU). It describes what the DEC has achieved in each phase, and probes into some essential problems that the DEC has attempted to solve.

This article provides a comprehensive description of the development of the DEC by following a case study method.

The DEC goes through three stages. In the first phase, a teacher‐focused policy and disciplined management are formed. In the second phase, a quality‐first policy is emphasized, and two training modes are developed: the human‐centered management mode and the trainee‐oriented training mode. In the third phase, the DEC initiates further innovation and uses a new platform.

ECNU has witnessed and participated in the development of modern distance education in China. It remains successful in developing distance education. The effort made by the DEC well showcases the overall development and growth of modern distance education in China.

This article presents the development of the DEC and will help readers understand the developmental process of distance education colleges in China.

This paper aims to improve the reliability of numerical methods for predicting the transient heat transfers in combustion chambers heated internally by moving heat sources.

A two-phase fluid dynamic model was used to govern the non-uniformly distributed moving heat sources. A Riemann-problem-based numerical scheme was provided to update the fluid field and provide convective boundary conditions for the heat transfer. The heat conduction in the solids was investigated by using a thermo-mechanical coupled model to obtain a reliable expanding velocity of the heat sources. The coupling between the combustion and the heat transfer is realized based on user subroutines VDFLUX and VUAMP in the commercial software ABAQUS.

The capability of the numerical scheme in capturing discontinuities in initial conditions and source terms was validated by comparing the predicted results of commonly used verification cases with the corresponding analytical solutions. The coupled model and the numerical methods are capable of investigating heat transfer problems accompanied by extreme conditions such as transient effects, high-temperature and high-pressure working conditions.

The work provides a reliable numerical method to obtain boundary conditions for predicting the heat transfers in solids heated by expanding multiphase reactive flows.

This paper aims to investigate the crucial roles of textured surfaces on oil-impregnated polytetrafluoroethylene (PTFE) created by a facile tattoo strategy in improving tribological properties.

Pored PTFE (PPTFE) was prepared by mixing powder PTFE and citric acid and experienced a cold-press sintering molding process. Subsequently, textured surfaces were obtained with using a tattoo strategy. Surface-textured PPTFE was thus impregnated with polyethylene glycol 200, yielding oil-impregnated and pore-connected PPTFE.

This study found that oil-impregnated and surface-textured PPTFE exhibited excellent tribological performances with an 82% reduction in coefficient of friction and a 72.5% lowering in wear rate comparing to PPTFE.

This study shows an efficient strategy to improve the tribological property of PTFE using a tattoo-inspired surface texturing method.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2024-0378/

This study aims to present a numerical study on the flow and heat transfer performance of a water-cooled tube with protrusions in different geometrical parameters.

A new type of enhanced heat exchanger tube is designed. Protrusions are formed on the inner surface of the tube by mechanical expansion, compression and other processing methods. A three-dimensional numerical symmetry model is established by ANSYS for studying the influence of protrusion distance, protrusion radius and protrusion arrangement on flow and heat transfer characteristics in turbulent flow.

The results show that the protrusions increase the heat transfer area and improve the heat transfer effect but also increase the flow resistance. Performance evaluation criteria (PEC) is applied to evaluate the flow and heat transfer characteristics of convex tubes. When adopting the aligned protrusions arrangement, the radius of 2 mm and distance of twice the protrusion radius is most heat transfer effect. The PEC of protrusion tubes with a staggered arrangement are higher than those in aligned arrangement, and the maximum value is 2.36 when Reynolds number is 12,000.

At present, most of the protrusion technology applications are based on the cold plate heat dissipation of electronic devices, and the flow path is rectangular. Convex tube heat exchanger is a high-efficiency heat exchanger, which uses convex tubes instead of smooth tubes in tubular heat exchangers to enhance heat transfer and widely used in petroleum, chemical, textile, oil refining and other industries.

This paper aims to regulate the oil retention rate and tribological properties of pored polytetrafluoroethylene (PPTFE) using polyvinyl alcohol (PVA)-based oil gel.

PPTFE was first prepared by using citric acid (CA) as an efficient pore-making agent. Subsequently, PVA and chitosan solution was introduced into the pores and experienced a freezing-thawing process, forming PVA-based gels inside the pores. Then, the PPTFE/PVA composite was impregnated with polyethylene glycol 200 (PEG200), yielding an oil-impregnated PPTFE/PVA/PEG200 composite.

It was found that the oil-impregnated PPTFE/PVA/PEG200 composite exhibited advanced tribological properties than neat PTFE with reductions of 53% and 70% in coefficient of friction and wear rate, respectively.

This study shows an efficient strategy to regulate the tribological property of PTFE using a PVA-based oil-containing gel.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2024-0432/