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This study aims to analyse the non-linear losses of a porous media (stack) composed by parallel plates and inserted in a resonator tube in oscillatory flows by proposing numerical correlations between pressure gradient and velocity.

The numerical correlations origin from computational fluid dynamics simulations, conducted at the microscopic scale, in which three fluid channels representing the porous media are taken into account. More specifically, for a specific frequency and stack porosity, the oscillating pressure input is varied, and the velocity and the pressure-drop are post-processed in the frequency domain (Fast Fourier Transform analysis).

It emerges that the viscous component of pressure drop follows a quadratic trend with respect to velocity inside the stack, while the inertial component is linear also at high-velocity regimes. Furthermore, the non-linear coefficient b of the correlation ax + bx² (related to the Forchheimer coefficient) is discovered to be dependent on frequency. The largest value of the b is found at low frequencies as the fluid particle displacement is comparable to the stack length. Furthermore, the lower the porosity the higher the Forchheimer term because the velocity gradients at the stack geometrical discontinuities are more pronounced.

The main novelty of this work is that, for the first time, non-linear losses of a parallel plate stack are investigated from a macroscopic point of view and summarised into a non-linear correlation, similar to the steady-state and well-known Darcy–Forchheimer law. The main difference is that it considers the frequency dependence of both Darcy and Forchheimer terms. The results can be used to enhance the analysis and design of thermoacoustic devices, which use the kind of stacks studied in the present work.

Special and differential treatment (SDT) in the World Trade Organisation (WTO) has failed to integrate developing countries into the international trading system, as contemplated by the WTO Agreement, itself. This paper aims to interrogate the current application of SDT by WTO members as the possible undermining factor for SDT not delivering on its objective.

The research uses a qualitative legal methodology. This study conducts desk analysis of primary legal materials and existing literature to assess current reflections of SDT and draw lessons for reforms in the WTO.

From interrogating current SDT practice in the WTO and a comparative analysis with a similar differential treatment under the Montreal Protocol, this paper finds that indeed, the problem lies in the current approach to SDT application in the WTO. This study finds that the existing absence of eligibility criteria for determining access to SDT by countries is the core reason for the abuse and sub-optimal outcome from its application.

While making a case for a rules-based approach to differentiation in the WTO, this paper proposes a unique methodology for differentiating between developing countries for SDT, including the use of a composite indicator to ensure that indicators that are used sufficiently reflect their heterogeneous needs. Drawing inspiration from Gonzalez et al. (2011a), this study introduces an adaptation for selecting a threshold for graduation. Specifically, the proposal on the value of the standard deviation of countries from the weighted mean of the composite indicator as the threshold for graduating countries from SDT is novel.

A survey of young microfirms was conducted to investigate their growth intentions. The findings confirm the distinct profiles of four types of firms categorized on the basis of current and future employment: Lifestyler, Entrepreneur, Manager, and Mover. They differ in terms of the owner's perceptions of the desirability and practicality of growing their firm, and with respect to the moderating variables of industry affiliation, business location, and investment level. Research issues and service implications for business support agencies are identified.

The proliferation of industry platforms has disrupted several industries. Firms adopting a platform business model have experienced a substantial expansion in size and scale, positioning themselves as the foremost valuable entities in market capitalization. Over the past two decades, there has been a substantial expansion in the body of literature dedicated to platforms, and different streams of research have emerged. Despite considerable efforts and the significant progress made in recent years toward a comprehensive understanding of industry platforms, there is still room for further harnessing the field’s diversity. As a result, the aim of this article is to examine the field’s structure, identify research concerns and provide suggestions for future research, thereby enhancing the overall understanding of industry platforms.

We conducted a thorough examination of 458 articles on the topic using bibliometric methods and systematic review techniques.

Through co-citation analysis, we identified five distinct clusters rooted in various bodies of literature: two-sided markets, industry platforms, digital platforms, innovation platforms and two-sided networks. Furthermore, the examination of these five clusters has revealed three key areas that demand further consideration: (1) terminologies, (2) classifications and (3) perspectives.

While previous reviews have provided valuable insights into the topic of industry platforms, none have explored the structure of the field so far. Consequently, as a first step toward advancing the field, we uncover the structure of the literature, identifying three major areas of concern. By addressing these concerns, our goal is to converge different clusters, thereby harnessing the diversity in the field and enhancing the overall understanding of industry platforms.

This study investigates the ability of crime management expenses, recognised external quality certification and ownership structure to describe the cross-sectional changes in the capital and labour efficiencies of manufacturing firms in middle income economies. It controls for the potential effects of graft incidence and firm age on firm-level efficiency.

The study adopts a state space model approach within the context of cross-sectional regressions. Data for the study are obtained from the World Bank Enterprise Survey for 2006, 2009, 2013, 2016 and 2019.

The study provides evidence that crime management expenses impact labour efficiency negatively. Also, its effect on capital efficiency is positive in 2019 and negative in 2013 and 2016 eras. Additionally, external auditor services and internationally recognised quality certification increase labour and capital efficiencies. Graft incidence exerts negative and positive effect on capital efficiency in the recent and earlier periods respectively. In addition, older firms tend to have higher labour efficiency, whilst younger firms have higher capital efficiency. There is evidence of firm size and export orientation effects in the drivers of efficiency.

Policies aimed at creating graft and crime-free business environment will enhance the efficiency and growth of firms' particularly for small firms. Also, the market rewards recognised quality assurance and good reputation.

According to the conventional wisdom, trade is not a zero-sum game, but a positive-sum game. By allowing countries to focus on producing the goods that they can produce relatively efficiently, free trade is largely beneficial for everyone involved. Then, why are the world’s two largest economies (i.e. the USA and China) currently engaged in a trade war, which is likely to hurt their own economies? What is the driving force for the trade war between the two economic giants? The purpose of this paper is to offer an explanation of the underlying cause of the US–China trade war.

In an effort to make sense of the trade war between the USA and China, the paper draws the insights from the two international relations theories – i.e. hegemonic stability theory and power transition theory.

As China continues to threaten US hegemony in the world in general and East Asia in particular, the Sino–US competition for hegemony will intensify over time. As a result, the trade war between the two countries may persist longer than many anticipate. Further, even if the trade war between the two superpowers ends soon, a similar type of conflict is likely to occur later as long as the Sino–US hegemonic rivalry continues.

The central thesis of this paper is that “US fear” about its declining hegemony and China’s rapid rise as a challenger of US hegemony is driving a US-launched trade war with China. Since the underlying cause of the trade war between the world’s two largest economies is political (i.e. the Sino–US hegemonic rivalry) rather than economic (e.g. US attempts to improve the trade balance with China by imposing tariffs on Chinese goods), the paper contends that the full understanding of the trade war requires close attention to the importance of power competition between the two superpowers.

In this study in the United Arab Emirates (UAE), we investigated college students’ perceptions of their past experience of receiving one-to-one tutoring support in mathematics when they were in secondary school. In addition, we also explored students’ reasons for taking one-to-one tutoring in mathematics, the perceived impact of one-to-one tutoring in overcoming shortcomings of school mathematics teaching and on their mathematics achievement, and whether the learning environment at school influenced decisions about having one-to-one tutoring. Eight case-study students were involved in recalling how beneficial one-to-one tutoring was through semi-structured interviews. Because of the small sample size, the research involved only qualitative data based on the recollections of college students who were attending a one-year course in the General Education department of Abu Dhabi Men’s College. The research provided valuable insights into how some students considered having a one-to-one tutor beneficial for their achievement when they were in secondary school. Educators must consider students’ learning environment as being one of the main reasons for deciding whether or not to undertake one-to-one tutoring to raise their achievement in mathematics.

ﻓﻲ ھذه اﻟد را ﺳﺔ ﻓﻲ دوﻟ ﺔ ا ﻹﻣﺎ را ت اﻟ ﻌرﺑﯾﺔ اﻟ ﻣﺗ ﺣدة، د رﺳﻧﺎ ﺗ ﺻورا ت طﻼب اﻟ ﺟﺎ ﻣﻌﺎ ت ﻋن ﺗ ﺟرﺑﺗﮭم اﻟ ﺳﺎﺑﻘﺔ ﻓﻲ ﺗﻘدﯾم د ﻋم ﺗﻌﻠﯾﻣ ﻲ ﻓ رد ي ﻓﻲ اﻟ رﯾﺎ ﺿﯾﺎ ت ﻋﻧدﻣﺎ ﻛﺎﻧ وا ﻓﻲ اﻟ ﻣد رﺳﺔ اﻟﺛﺎﻧ وﯾﺔ. ﺑﺎ ﻹ ﺿﺎﻓﺔ إ ﻟ ﻰ ذ ﻟ ك ، ا ﺳ ﺗ ﻛ ﺷ ﻔ ﻧ ﺎ أ ﯾ ﺿً ﺎ أ ﺳ ﺑ ﺎ ب ا ﻟ ط ﻼ ب ﻹ ﺟ ر ا ء د ر و س ﻓ ر د ﯾ ﺔ ﻓ ﻲ اﻟر ﯾﺎ ﺿ ﯾﺎ ت ، وا ﻟﺗﺄﺛﯾ ر اﻟ ﻣﻠ ﺣو ظ ﻟﻠ د رو س اﻟﻔ ردﯾ ﺔ ﻋﻠ ﻰ ﺗ ﺣ ﺻ ﯾﻠ ﮭم ﻓ ﻲ اﻟر ﯾﺎ ﺿ ﯾﺎ ت ، وﻣ ﺎ إذا ﻛﺎﻧ ت ﺑﯾﺋﺔ اﻟﺗ ﻌﻠم ﻓ ﻲ اﻟ ﻣد رﺳﺔ ﻗد أﺛ ر ت ﻋﻠ ﻰ اﻟﻘ را را ت اﻟ ﻣﺗ ﻌﻠﻘﺔ ﺑﺎ ﻟ ﺣ ﺻ ول ﻋ ﻠ ﻰ ﺗد ر ﯾ ب ﻓ ر د ي . د ر س وا ﺣ د. ﺷ ﺎ ر ك ﺛ ﻣﺎﻧ ﯾ ﺔ ﻣ ن ط ﻼ ب د ر ا ﺳ ﺔ اﻟﺣ ﺎﻟ ﺔ ﻓ ﻲ اﻟﺗذﻛﯾ ر ﺑ ﻣد ى ﻓﺎﺋدة اﻟﺗد رﯾ س اﻟﻔ رد ي ﻣ ن ﺧﻼل ﻣ ﻘ ﺎ ﺑ ﻼ ت ﺷ ﺑ ﮫ ﻣ ﻧ ظ ﻣ ﺔ . ﻧ ظ رً ا ﻟ ﺻ ﻐ ر ﺣ ﺟ م ا ﻟ ﻌ ﯾ ﻧ ﺔ ، ﺗ ﺿ ﻣ ن ا ﻟ ﺑ ﺣ ث ﻓ ﻘ ط ﺑ ﯾ ﺎ ﻧ ﺎ ت ﻧ و ﻋ ﯾ ﺔ ا ﺳ ﺗ ﻧ ﺎ دًا إ ﻟ ﻰ ذ ﻛ ر ﯾ ﺎ ت ط ﻼ ب ا ﻟ ﺟ ﺎ ﻣ ﻌ ﺎ ت ا ﻟ ذ ﯾ ن ﺣ ﺿ ر و ا دو رة ﻣدﺗ ﮭﺎ ﻋﺎم وا ﺣد ﻓ ﻲ ﻗ ﺳم اﻟﺗ ﻌﻠﯾم اﻟ ﻌﺎم ﻓ ﻲ ﻛﻠﯾﺔ أﺑو ظ ﺑ ﻲ ﻟ ﻠ ط ﻼ ب . ﻗ د م ا ﻟ ﺑ ﺣ ث ر ؤ ى ﻗ ﯾّﻣ ﺔ ﺣ و ل ﻛﯾ ﻔﯾ ﺔ ﻧ ظر ﺑ ﻌ ض اﻟ طﻼب ﻓ ﻲ وﺟود ﻣد ر س وا ﺣد ﻣﻔﯾد ﻟﺗ ﺣﻘﯾﻘ ﮭم ﻋﻧدﻣ ﺎ ﻛﺎﻧ وا ﻓ ﻲ اﻟ ﻣد رﺳﺔ اﻟﺛﺎﻧ وﯾ ﺔ. ﯾ ﺟ ب ﻋﻠ ﻰ اﻟ ﻣﻌﻠ ﻣﯾ ن ا ﻋﺗﺑﺎ ر ﺑﯾﺋ ﺔ ﺗ ﻌﻠم اﻟ طﻼب وا ﺣدة ﻣ ن ا ﻷﺳﺑﺎ ب اﻟ رﺋﯾ ﺳﯾ ﺔ ﻟﺗ ﻘ ر ﯾ ر ﻣﺎ إ ذا ﻛﺎ ن ﯾ ﺟ ب ﻋ ﻠﯾﮭم إ ﺟ ر ا ء د ر و س ﻓ ر دﯾ ﺔ أ م ﻻ ﻟ ر ﻓ ﻊ ﻣ ﺳ ﺗ و ى ﺗ ﺣ ﺻ ﯾﻠﮭم ﻓ ﻲ اﻟ ر ﯾﺎ ﺿ ﯾﺎ ت .