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This study aims to develop an experimentally validated three-dimensional numerical model for predicting different flow patterns produced with a gas dynamic virtual nozzle (GDVN).

The physical model is posed in the mixture formulation and copes with the unsteady, incompressible, isothermal, Newtonian, low turbulent two-phase flow. The computational fluid dynamics numerical solution is based on the half-space finite volume discretisation. The geo-reconstruct volume-of-fluid scheme tracks the interphase boundary between the gas and the liquid. To ensure numerical stability in the transition regime and adequately account for turbulent behaviour, the k-ω shear stress transport turbulence model is used. The model is validated by comparison with the experimental measurements on a vertical, downward-positioned GDVN configuration. Three different combinations of air and water volumetric flow rates have been solved numerically in the range of Reynolds numbers for airflow 1,009–2,596 and water 61–133, respectively, at Weber numbers 1.2–6.2.

The half-space symmetry allows the numerical reconstruction of the dripping, jetting and indication of the whipping mode. The kinetic energy transfer from the gas to the liquid is analysed, and locations with locally increased gas kinetic energy are observed. The calculated jet shapes reasonably well match the experimentally obtained high-speed camera videos.

The model is used for the virtual studies of new GDVN nozzle designs and optimisation of their operation.

To the best of the authors’ knowledge, the developed model numerically reconstructs all three GDVN flow regimes for the first time.

The purpose of this paper is to investigate the salivary fluoride retention as fluoride concentration, amount of soluble fluoride, half-life (t_1/2) and salivary flow rate of different amounts of toothpaste and rinsing procedures.

A randomized crossover study of 21 healthy volunteers was designed to compare pharmacokinetic parameters of 1 g (B1) and 0.3 g (B0.3) of toothpaste without rinsing and brushing with 1 g of toothpaste with expectoration followed by water rinsing (B1R). Unstimulated saliva was collected before brushing as a baseline and at 0, 5, 10, 30, 60 and 90 min after the completion of the tooth brushing procedure.

The salivary fluoride concentration and amount of soluble fluoride of the B1 group were significantly higher than the B0.3 and B1R groups. The B1 and B1R groups prolonged the remineralizing level up to 60 min while the B0.3 group retained their remineralizing levels for 30 min. The initial t_1/2 (rapid phase) of B1 and B1R groups were significantly longer than the B0.3 group. The late t_1/2 (slow phase) of the B0.3 group was significantly longer than the B1 group. This is called the two-compartment open pharmacokinetics model. There was no statistical difference of salivary flow rates between all groups.

Non-rinsing and the amount of fluoride toothpaste play an important role in raising salivary fluoride levels and prolonging the remineralizing level of the oral cavity.

Trade relations between China and the USA have been marked by conflict, especially since China’s membership in the World Trade Organization (WTO). These conflicts have been analyzed from a variety of perspectives, including the loss of jobs in the USA due to Chinese imports, competition in high technology sectors and the balance of trade. Conceptual frameworks have employed models of domestic differences as well as models of international power distribution. Among domestic differences examined are the existence of state-owned enterprises in China compared to the domination of the USA economy by private firms, the large role of the Communist Party in China and the influence of labor and environmental and labor groups in the USA. Power distribution theories focus on the systemic effects of the distribution of power on trade openness and on the pattern of intra-bloc versus between-bloc trade. This paper aims to examine the role of macroeconomic policy factors in China and the USA, in particular, the role of national patterns of savings, investment and consumption (both private and government). The paper concludes that insofar as the balance of trade is an important component of the trade conflict, domestic macroeconomic factors continue to be important. The resolution of the conflict will have to take into account the respective macroeconomic policies of China and the USA.

The design is an analytic case study of US–China trade relations with a particular focus on the balance of trade. The conceptual framework employed involves an analysis of macroeconomic policy categories, especially the overall pattern of savings (household, firm and government), investment and consumption. Process tracing over time since China's membership in the WTO is carried out with an eye toward the relationship between the balance of trade and macroeconomic policy.

The main findings are that there is a strong relation between the respective macroeconomic policies of the USA and China and their trade relations. The domestic political economy of the USA encourages consumption and a low rate of savings. The opposite is true of China where household income is low by design and national savings are high. China depends on the USA to consume what is not consumed domestically. The USA depends on Chinese imports for additional consumption encouraged by its low rate of savings. The two economies are locked in a mutual dependence.

Key research implications are that there should be more focus on domestic macroeconomic policies since these are the root causes of the trade imbalance. This is not to say that trade frictions centering on jobs, subsidies and competition in high technology are unimportant. However, without the resolution of differences in the management of macroeconomic policies, trade conflicts between the USA and China will continue.

Practical implications are huge, in some ways much more important than the academic implications. Macroeconomic policy differences in savings, investment, government spending, taxation and infrastructure are important. Furthermore, there are available tools in both China and the USA to manage the macroeconomy, particularly, monetary and fiscal policy.

One implication of this paper is that satisfaction or dissatisfaction of workers is dependent on income distribution which in turn affects trade. Treatment of people in different socioeconomic categories, such as the elderly, the young, and those at working age are a function of macroeconomic policies.

Many people have written about macroeconomics. It is a conventional subfield of economics. The originality of this paper lies in its advocacy of a shift of focus and attention and in the argument that traditional macroeconomics is related to trade. Despite its importance, macroeconomics has not been the center of attention for most political scientists, though economists have made it more central.

There exist long-term fluctuations in the process of capital accumulation. The economic long wave is an essential part of research into non-mainstream western economics. After the Second World War, the capitalist world experienced the fourth long wave of expansion and then entered into a downward phase of the long wave in the 1970s. Regarding to whether a new long wave of expansion took place in the 1980s, left-wing scholars hold different viewpoints. The purpose of this paper is to focus on this issue.

First, based on the review of the long wave history, this paper discusses three kinds of long wave theories with significant influence and puts forward the theoretical framework of analyzing the long wave of capitalist economy. Next, under the guidance of this theoretical framework and in combination with the actual development and evolution of the capitalist economy, the issue of whether the fifth long wave of the capitalist economy began to emerge in the 1980s is discussed deeply.

This paper argues that, from the early 1980s to 2007, the US-dominated developed countries experienced a new long wave of expansion driven by the information technology revolution, the adjustment of the neoliberalism system and the economic globalization. However, the financial-economic crisis of 2008–2009 led to a new phase of long wave downswing.

This paper does not agree with the single-factor analysis of the intrinsic formation mechanism of economic long wave and sticks to the multi-factor analysis centering on the fluctuation of accumulation rate. It is pointed out that the evolution of the long wave of capitalist economy depends on the combined influence of technology, institutions and market. The study of the long wave of the economy will help us to correctly understand the historical stage and characteristics of the current world capitalist economy in the long-term fluctuations, so that we can make an appropriate and positive response.

This paper aims to present the mathematical foundation of so-called advance algorithms, developed to compensate for defects during acceleration and deacceleration of the print head in filament-based melt extrusion additive processes. It then investigates the validity of the mathematical foundation, its performance on a low-cost system and the effect of changing layer height on the algorithm’s associated process parameter.

This study starts with a compilation and review of literature associated with advance algorithms, then elaborates on its mathematical foundation and methods of implementation. Then an experiment displaying the performance of the algorithm implemented in Marlin machine firmware, Linear Advance 1.0, is performed using three different layer heights. The results are then compared with simulations of the system using Simulink.

Findings suggests that advance algorithms following the presented approach is capable of eliminating defects because of acceleration and deacceleration of the print head. The results indicate a layer height dependency on the associated process parameter, requiring higher compensation values for lower layer heights. It also shows higher compensation values for acceleration than deacceleration. Results from the simulated mathematical model correspond well with the experimental results but predict some rapid variations in flow rate that is not reflected in the experimental results.

As there are large variations in printer design and materials, deviation between different setups must be expected.

To the best of authors’ knowledge, this study is the first to describe and investigate advance algorithms in academic literature.

International business as a field values perspectives from various contexts, but scholars from emerging markets face a number of often-unseen challenges preventing them from fully contributing to the field. This study aims to explain those challenges and what the author has done to manage them.

This is a Reflexive piece in which the author makes sense of her own experience as a scholar not only of but also in an emerging market, as well as the experiences at her school in seeking to develop a high-quality doctoral program.

When leading scholars interact, whether in writing or in person, they tend to be in academically and otherwise well-resourced locations. This is true even for the leading international business scholars of emerging markets, and it imposes time and financial costs on scholars located in emerging markets wanting to participate in such conversations. Having experienced such challenges, the author worked with colleagues to design a doctoral program that could nurture rich scholarly conversations at the school. However, there remains a clear and pervasive tension between the inclusive aspirations of the field and the tendency for cutting-edge academic conversations to be concentrated in the developed world.

The experiences of emerging market scholars remain underrepresented in the field. By drawing on her own experience, both as a scholar and the head of the doctoral program at her school, the author provides suggestions for how to think about and develop a more inclusive scholarly conversation.

Relations in university settings are becoming more heterogeneous in terms of race, ethnicity, religion, nationality, class, and gender. In South Africa, transformation imperatives have radically changed the complexion of the country’s university campuses but have also entrenched political imperatives in its universities. As a consequence, the university is a highly politicised space. This is not new. What is new is a communication environment characterised by real-time, global networked digital communication and the uptake of digital media platforms (including social media platforms). We explore the effects of politicisation and new modes of communication using the case of a controversial article published in a South Africa journal and the ensuing polemic. Drawing on both institutional theory and Castells’ description of the network society, we conceptualise collegiality along two dimensions: horizontal collegial relations which exist for the purpose of knowledge creation and transfer which, in turn, depends on self-governance according to a taken-for-granted code of conduct; and vertical collegiality which describes collegial relations between academic staff and university management, and which is necessary for the governance of the university as a complex organisation. We conclude that the highly personal nature of communication that is propelled by digital communication has a direct impact on collegial relations within the university. The motivations of both university academic staff and management, as well as the public, extend beyond stimulating collective debate in the service of knowledge production to serving individual and/or ideological agendas as the communication of science becomes politicised. While issues pertaining to collegiality in South Africa may at first glance appear to be unique to the country, we believe that in a globally transforming academy, the South African case may offer novel insights and useful lessons for other highly politicised university systems.

This paper aims to analyze the pressure distribution of rectangular aerostatic thrust bearing with a single air supply inlet using the complex potential theory and conformal mapping.

The Möbius transform is used to map the interior of a rectangle onto the interior of a unit circle, from which the pressure distribution and load carrying capacity are obtained. The calculation results are verified by finite difference method.

The constructed Möbius formula is very effective for the performance characteristics researches for the rectangular thrust bearing with a single air supply inlet. In addition, it is also noted that to obtain the optimized load carrying capacity, the square thrust bearing can be adopted.

The Möbius transform is found suitable to describe the pressure distribution of the rectangular thrust bearing with a single air supply inlet.

This Impact Pathways paper aims to provide a timely and structured discussion of real-world problems at Marks and Spencer and in retail in general, evoked through the current COVID-19 pandemic.

The article presents collaborative research based on more than five hours of interviews and several iterative paper writing steps between management scholars and Marks & Spencer’s Head of Procurement - Logistics and Supply Chain. Continuous discussions for more than ten months among the research team assure the timeliness and relevance of the findings. The exceptional position of the executive and his career biography allowed the integration of a variety of intra-organisational and inter-organisational stakeholders.

This paper highlights the impacts of the current COVID-19 pandemic on operations and supply chain management (OSCM) in the retail industry, structured in upstream, internal and operational, and downstream and customer perspectives. The paper concludes with a practice-infused research agenda, which aims to trigger relevant research about the current and potential future crises.

Although the research agenda is directly related to the COVID-19 pandemic and the retail industry, the future research pathways are expected to inform business responses to potential future external shocks other than pandemics and in different industries as well.

Despite a plethora of studies already published on COVID-19 and OSCM, little is known on how the outbreak affects specific firms and industries. This paper offers an overview of COVID-19 related change as it happens at the retailer and in the retailing industry in general. This article is among the first to provide a practice-infused call for research on urgent issues being faced by business leaders directly relevant to our domain.

The construction of cement asphalt (CA) emulsified mortar can obviously disturb the slab status after the fine adjustment. To decrease or eliminate the influence of CA mortar grouting on track slab geometry status, the effects of grouting funnel, slab pressing method, mortar expansion ratio, seepage ratio and grouting area on China Railway Track System Type (CRTS I) track slab geometry status were discussed in this paper.

Combined with engineering practice, this paper studied the expansion law of filling layer mortar, the liquid level height of the filling funnel, the pressure plate device and the amount of exudation water and systematically analyzed the influence of filling layer mortar construction on the state of track slab. Relevant precautions and countermeasures were put forward.

The results showed that the track slab floating values of four corners were different with the CA mortar grouting and the track slab corner near CA mortar grouting hole had the maximum floating values. The anti-floating effect of “7” shaped slab pressing device was more efficient than fixed-joint angle iron, and the slab floating value could be further decreased by increasing the amount of “7” shaped slab pressing devices. After CA mortar grouting, the track slab floating pattern had a close correlation with the expansion rate and water seepage rate of CA mortar over time and the expansion and water seepage rate of the mortar were faster when the temperature was high. Furthermore, the use of strip CA mortar filling under the rail bearing platform on both sides could effectively reduce the float under the track slab, and it could also save mortar consumption and reduce costs.

This study plays an important role in controlling the floating values, CA mortar dosage and the building cost of projects by grouting CA mortar at two flanks of filling space. The research results have guiding significance for the design and construction of China's CRTS I, CRTS II and CRTS III track slab.