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The purpose of this paper is to analyze lubrication characteristics of a bidirectional thrust bearing in a pumped storage, considering the effect of the thermal elastic deformation of the pad and collar.

This study used the fluid–solid interaction (FSI) technique to investigate the lubrication characteristics of a bidirectional thrust bearing for several typical operating conditions. The influences of the operating conditions and the thrust load on the lubrication characteristics were analyzed. Then, various pivot eccentricities were investigated to analyze the effects of the pivot position.

It is found that the effect of the radial tilt angle of the collar runner on the oil film is compensated for by the radial tilt of the pad. The central pivot support system is the main factor limiting the loads of bidirectional thrust bearings.

This paper has preliminarily revealed the lubrication mechanism of bidirectional tilting-pad thrust bearings. A three-dimensional FSI method is suggested to evaluate the thermal–elastic–hydrodynamic deformations of thrust bearings instead of the conventional method, which iteratively solves the Reynolds equation, the energy equation, the heat conduction equation and the elastic equilibrium equation.

South Africa is the highest consumer of commercial energy per capita in Africa, ranking 16th in the world for primary energy consumption. It is also ranked among the bottom 50 of the 150 countries regarding energy efficiency. The cold chain is a large contributor through refrigerated transport vehicles. To comply with the changing climate regulations, cryogenic and eutectic systems are systems with great potential for small distance refrigerated transport. The purpose of this paper is to introduce eutectic system to medium distance refrigerated transport.

This study presents the potential use of Eutectic plates inside a medium refrigerated transport vehicle, by numerically investigating the characteristics of phase change material eutectic plates applied at low-temperature ranges. A physical model and a mathematical model for three-dimensional transient natural flow were developed as proposed by Xiaofeng and Zhang. Using the governing equation of mass, momentum and energy conservation, three Eutectic plate configurations were modeled and simulated in ANSYS Fluent for 5 h.

A uniform heat transfer and airflow condition inside a refrigerated compartment were predicted using the Reynolds stress model. The configuration with eutectic plates placed at the top and side showed great potential for the system functioning in the South African climate.

Medium refrigerated transport vehicle.

This configuration had a high-temperature distribution across the compartment and promoted high air circulations, showing that it could be ideal for medium refrigerated transport vehicles delivering perishable foodstuffs or non-food goods.

The purpose of this research is to explore the relationship between supervisor-subordinate Guanxi (SSG) and employee affective commitment. Integrating social exchange theory (SET) with conservation of resource (COR) theory, this paper explores the mixed effect of SSG on affective commitment as well as the moderating roles of an individual difference (subordinate work ethic) and a contextual variable (procedural fairness).

This research adopted a survey involving 249 subordinates to test the hypothesized model.

The results showed that the relationship between SSG and affective commitment was inverted U-shaped, and this relationship was moderated by work ethic and procedural fairness, respectively.

Despite those contributions listed above, there are still some limitations that future research should seek to address. First, the data of this research are cross-sectional, which might cause common method bias to responses. However, all the hypotheses are higher-order forms of the main effects (curvilinear and moderating effects), which are not affected by the cross-sectional nature of the study (Podskoff et al., 2003). Moreover, given these variables in the model are related to subordinates' internal psychological states or perceptions, data for the study should be collected from subordinates. Relatedly, the cross-sectional nature of the dataset may raise a question about the directionality of the relationships. However, the research model is based on strong theories (i.e. SET and COR theory). In addition, prior research has indicated that Guanxi has an influence on commitment, not vice versa (Cheung et al., 2009; Chen and O'Leary, 2018). However, given that only experimental design can conclusively prove the directionality of the relationship, the authors encourage to replicate the current study using such a design. In addition, the authors encourage future studies to collect longitudinal data and replicate the current study. Second, this study only tested how work ethic and procedural fairness moderated the relationship between SSG and affective commitment. The authors encourage future research to explore the moderating effect of other moderators, such as the integrity of supervisors. In particular, when the supervisor has a high level of integrity, the negative influence of higher SSG may be weakened. Third, this study did not explore the mechanism linking SSG with affective commitment. Future studies should explore the potential mechanisms. For example, subordinates' emotional exhaustion might be the potential mechanism between SSG and affective commitment.

The results imply that supervisors should treat SSG as a double-edged sword and maximize the positive influence of SSG. In addition, organizations should hire individuals with high work ethic or provide related training. At last, organizations should realize the importance of procedural fairness and set a sector that oversees making and executing well-designed roles.

Previous studies on SSG mainly focused on its positive effect on affective commitment, neglecting to explore its negative effect. This paper helped to illustrate the relationship between SSG and affective commitment comprehensively by indicating the relationship between SSG and affective commitment was inverted U-shaped and moderated by work ethic and procedural fairness, respectively.

In typical model-based calibration, linearization errors are derived inevitably, and non-negligible negative impact will be induced on the identification results if the rotational kinematic errors are not small enough or the lengths of links are too long, which is common in the industrial cases. Thus, an accurate two-step kinematic calibration method minimizing the linearization errors is presented for a six-DoF serial robot to improve the calibration accuracy.

The negative impact of linearization on identification accuracy is minimized by removing the responsible linearized kinematic errors from the complete kinematic error model. Accordingly, the identification results of the dimension-reduced new model are accurate but not complete, so the complete kinematic error model, which achieves high identification accuracy of the rest of the error parameters, is combined with this new model to create a two-step calibration procedure capable of highly accurate identification of all the kinematic errors.

The proportions of linearization errors in measured pose errors are quantified and found to be non-negligible with the increase of rotational kinematic errors. Thus, negative impacts of linearization errors are analyzed quantitatively in different cases, providing the basis for allowed kinematic errors in the new model. Much more accurate results were obtained by using the new two-step calibration method, according to a comparison with the typical methods.

This new method achieves high accuracy with no compromise on completeness, is easy to operate and is consistent with the typical method because the second step with the new model is conveniently combined without changing the sensors or measurement instrument setup.

The purpose of this paper is to explore the possibility of an enhanced continuous liquid interface production (CLIP) with a porous track-etched membrane as the oxygen-permeable window, which is prepared by irradiating polyethylene terephthalate membranes with accelerated heavy ions.

Experimental approaches are carried out to characterize printing parameters of resins with different photo-initiator concentrations by a photo-polymerization matrix, to experimentally observe and theoretically fit the oxygen inhibition layer thickness during printing under conditions of pure oxygen and air, respectively, and to demonstrate the enhanced CLIP processes by using pure oxygen and air, respectively.

Owing to the high permeability of track-etched membrane, CLIP process is demonstrated with printing speed up to 800 mm/h in the condition of pure oxygen, which matches well with the theoretically predicted maximum printing speed at difference light expose. Making a trade-off between printing speed and surface quality, maximum printing speed of 470 mm/h is also obtained even using air. As the oxygen inhibition layer created by air is thinner than that by pure oxygen, maximum speed cannot be simply increased by intensifying the light exposure as the case with pure oxygen.

CLIP process is capable of building objects continuously instead of the traditional layer-by-layer manner, which enables tens of times improvement in printing speed. This work presents an enhanced CLIP process by first using a porous track-etched membrane to serve as the oxygen permeable window, in which a record printing speed up to 800 mm/h using pure oxygen is demonstrated. Owing to the high permeability of track-etched membrane, continuous process at a speed of 470 mm/h is also achieved even using air instead of pure oxygen, which is of significance for a compact robust high-speed 3D printer.

Against the background of the digital economy, odd-job platforms rely on artificial intelligence algorithms to efficiently allocate tasks and monitor platform workers’ performance, putting these workers under enormous pressure. This paper explores the relationship between work overload and turnover intention of platform workers on odd-job platforms and the factors that lead to platform workers’ turnover.

Based on the job demands–resources model (JD-R), we construct a theoretical model to explain the relationship between work overload and turnover intention of platform workers. We test job burnout as a mediator variable and perceived algorithmic fairness and job autonomy as moderating variables. We conducted a study at food delivery platforms and ride-hailing platforms in China.

The empirical results show that: (1) work overload increases the turnover intention of platform workers by increasing job burnout and (2) perceived algorithmic fairness and job autonomy moderate the positive relationship between work overload and job burnout.

We provide a theoretical basis to explain the influence of work overload on turnover intention of odd-job platform workers and provide practical recommendations for management of platform workers.

This paper aims to feature preparation and characterization of thiokol oligomer functionalized MWCNTs/epoxy nanocomposites using low molecular weight polyamide as curing agent.

First, thiokol oligomer functionalized MWCNTs (MWCNTs-TO) were prepared through hydroxylation, silanization and graft modification of MWCNTs. The nanocomposite specimens were fabricated through sonication and cast moulding process. The authors then investigated the impact of MWCNTs-TO content on mechanical and thermal properties of the nanocomposites.

MWCNTs-TO with grafting ratio of 17.5 Wt.% was synthesized and characterized with X-ray photoelectron spectroscopy, thermal gravimetric analysis, Fourier transform infrared and scanning electron microscopy. The obtained epoxy nanocomposites exhibit improved mechanical properties and thermal stability with MWCNTs-TO added. Moreover, desirable results were obtained at 0.75 Wt.% of MWCNTs-TO loading: the young’s modulus, tensile, flexural and impact strength increased by 24.6,72.8,34.8 and 82.7%, respectively, compared to the neat epoxy. The improvement of mechanical properties is mainly attributed to enhanced interfacial interaction and dispersion between the covalent functionalized MWCNTs and epoxy matrix.

A flexible thiokol oligomer was successfully grafted onto MWCNTs via a mild route. Nanocomposites with excellent interfacial interaction and dispersion between MWCNTs-TO and the epoxy matrix have been successfully fabricated and investigated.

This method provided a mild and practical approach to improve the performance of MWCNTs epoxy nanocomposites.

A flexible thiokol oligomer was successfully covalent grafted onto MWCNTs via a mild route. Nanocomposites with excellent interfacial interaction and dispersion between MWCNTs-TO and the epoxy matrix have been successfully fabricated and investigated.

The paper aims to propose a virtual reality (VR) wisdom teaching model in open university English course from the perspective of “Metaverse”. The study aims to testify the stimulation for English learning and the effectiveness of English-expressing with VR tools for adult learners from the practice in a pilot reform project.

The paper opted for an exploratory study using ICARE Design Model as the framework, under the grounded theories of constructivism and multi-modal teaching. The study compared the evaluation data of one-semester English learning performance between the experimental class (67 students) with VR practice and the controlled class (67 students), including speaking test score, qualitative feedback and in-depth experience analysis. The data were complemented by reflection paper analysis, including manual evaluation (the criteria of semantics, pronunciation, fluency and completeness), questionnaire survey (in the form of five-point Likert scale) and semi-structured interview.

The paper provides empirical insights about the VR wisdom teaching model in English language teaching and learning in a Chinese Open University. The empirical results suggest that “3I” features of VR technology could make up for the shortcomings of traditional English classes in open universities in China, and VR resources designed with curriculum teaching materials could also be helpful for students’ command of knowledge points and language skills. What’s more, the sense of authentic experience in virtual could promote the teaching and learning effect in college English classes.

The present study focuses on a wisdom mode of foreign language teaching and learning for adult learners in open education, so the research results may lack generalizability. Therefore, researchers are encouraged to further explore the deep integration of VR/artificial intelligence in foreign language teaching and learning.

This paper fulfills an identified need to study how VR tools provide an engaging, fun and immersive language learning environment, to enhance autonomous learning and learning engagement.

The aim of this paper is to solve the problem of low accuracy of traditional fatigue crack growth (FCG) prediction methods.

The GMSVR model was proposed by combining the grey modeling (GM) and the support vector regression (SVR). Meanwhile, the GMSVR model parameter optimal selection method based on the artificial bee colony (ABC) algorithm was presented. The FCG prediction of 7075 aluminum alloy under different conditions were taken as the study objects, and the performance of the genetic algorithm, the particle swarm optimization algorithm, the n-fold cross validation and the ABC algorithm were compared and analyzed.

The results show that the speed of the ABC algorithm is the fastest and the accuracy of the ABC algorithm is the highest too. The prediction performances of the GM (1, 1) model, the SVR model and the GMSVR model were compared, the results show that the GMSVR model has the best prediction ability, it can improve the FCG prediction accuracy of 7075 aluminum alloy greatly.

A new prediction model is proposed for FCG combined the non-equidistant grey model and the SVR model. Aiming at the problem of the model parameters are difficult to select, the GMSVR model parameter optimization method based on the ABC algorithm was presented. the results show that the GMSVR model has better prediction ability, which increase the FCG prediction accuracy of 7075 aluminum alloy greatly.

This paper is a response to the doctrine that capital is incompatible with public ownership. The fundamental characteristics of modern productivity determine the co-existence of the market economy and capital relations.

Socialism can neither bypass the market economy nor “go beyond capital”; capital appears in two historical forms, including the private capital and the public capital. Public capital is the inevitable outcome of the inherent contradictions of public ownership in a socialist market economy.

It represents an economic relationship that compels individual labourers to provide surplus labour for the society. The combination of the strong accumulation function of public capital and the improvement of people's welfare is the main cause of China's development miracle.

The innovation impetus of the public capital and its “immunity” to the capitalist crisis highlight the tremendous power of socialism with Chinese characteristics in breaking free of the shackles of capitalism and continuously developing productive forces. Public capital demonstrates and will continue to demonstrate the historical legitimacy of socialism.