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Grappling with the sweeping pandemic, the small hospitality business (SHB), smaller in scale and weaker in risk mitigation, has been seriously affected. The purpose of this study aims to supplement the unrepresented area of SHB in China from the digital perspective by drawing on instrumentalization theory (IT).

Based on two appropriate and detailed SHB cases, this paper adopted a qualitative approach to understand and conceptualize the focal issue.

This study identified the factors affecting SHB at operational, managerial and transformational levels amidst the crisis. It further developed a theoretical framework of the SHB rebound matrix, highlighting the importance of digitization and digitalization.

The research theoretically confirmed that SHB is internally, externally and essentially restricted and developed a corresponding rebound matrix. It practically supports SHB’s transformation by making recommendations to unleash the potential of digital business.

This study complements extant descriptive and atheoretical research by focusing on SHB’s underlying digital nature through the lens of IT, providing an evidenced theoretical understanding of SHB’s development amidst and after the pandemic.

Because of the various advantages of reinforcement learning (RL) mentioned above, this study uses RL to train unmanned aerial vehicles to perform two tasks: target search and cooperative obstacle avoidance.

This study draws inspiration from the recurrent state-space model and recurrent models (RPM) to propose a simpler yet highly effective model called the unmanned aerial vehicles prediction model (UAVPM). The main objective is to assist in training the UAV representation model with a recurrent neural network, using the soft actor-critic algorithm.

This study proposes a generalized actor-critic framework consisting of three modules: representation, policy and value. This architecture serves as the foundation for training UAVPM. This study proposes the UAVPM, which is designed to aid in training the recurrent representation using the transition model, reward recovery model and observation recovery model. Unlike traditional approaches reliant solely on reward signals, RPM incorporates temporal information. In addition, it allows the inclusion of extra knowledge or information from virtual training environments. This study designs UAV target search and UAV cooperative obstacle avoidance tasks. The algorithm outperforms baselines in these two environments.

It is important to note that UAVPM does not play a role in the inference phase. This means that the representation model and policy remain independent of UAVPM. Consequently, this study can introduce additional “cheating” information from virtual training environments to guide the UAV representation without concerns about its real-world existence. By leveraging historical information more effectively, this study enhances UAVs’ decision-making abilities, thus improving the performance of both tasks at hand.

WO₃ particles were prepared by the sol-gel method. Tetraethyl silicate (TEOS) was used to obtain a SiO₂-coated WO₃ nanoparticle. Quantum chemical parameters of oleic acid, triethanolamine, glycerol and methyl pentane as dispersants were theoretically calculated. Tribological properties of SiO₂/WO₃ nanocomposite lubricant were carried out on an MRS-10A four-ball friction and wear tester.

The purpose of this study is to investigate the preparation and tribological properties of SiO₂/WO₃ nanocomposite lubricant.

The obtained SiO₂-coated WO₃ nanoparticle (nano-SiO₂/WO₃) with a particle size of about 70 nm. The calculated adsorption energy of triethanolamine on the surface of the steel ball is 554.6 eV, and triethanolamine is selected as the dispersant. The dispersion effect of SiO₂/WO₃ nanocomposite lubricant is good, which shows that triethanolamine oleate plays a good dispersion role in the preparation of lubricant, which is consistent with the calculation results of the adsorption capacity of dispersant. As a good auxiliary lubricant, SiO₂ can improve the tribological properties and wear resistance of WO₃.

Nanocomposite lubricants have been the focus of research in recent years, which could greatly reduce energy consumption. And the SiO₂/WO₃ exhibited excellent lubrication performance as a lubricant additive. The lubrication mechanism of SiO₂/WO₃ nanocomposite lubricant is the synergistic lubrication mechanism of friction film lubrication and antifriction bearing. This study could provide a certain reference for the practical application of nanocomposite lubricants.

This paper aims to provide a series of new methods for projecting a three-dimensional (3D) object onto a free-form surface. The projection algorithms presented can be divided into three types, namely, orthogonal, perspective and parallel projection.

For parametric surfaces, the computing strategy of the algorithm is to obtain an approximate solution by using a geometric algorithm, then improve the accuracy of the approximate solution using the Newton–Raphson iteration. For perspective projection and parallel projection on an implicit surface, the strategy replaces Newton–Raphson iteration by multi-segment tracing. The implementation takes two mesh objects as an example of calculating an image projected onto parametric and implicit surfaces. Moreover, a comparison is made for orthogonal projections with Hu’s and Liu’s methods.

The results show that the new method can solve the 3D objects projection problem in an effective manner. For orthogonal projection, the time taken by the new method is substantially less than that required for Hu’s method. The new method is also more accurate and faster than Liu’s approach, particularly when the 3D object has a large number of points.

The algorithms presented in this paper can be applied in many industrial applications such as computer aided design, computer graphics and computer vision.

The purpose of this study is to investigate the influence of geometric parameters of removable panels on the sealing characteristics of ceramic wafer seal structure subjected to high-temperature gas flow.

Based on the laminar flow Reynolds equation, the theoretical and numerical calculation models were constructed to investigate the influence of external convex deformation of removable panel on leakage rate. The theoretical formula for leakage rate after deformation of the removable panel was derived, and the flow field and leakage characteristics of ceramic wafer seal under different operating parameters were studied.

The leakage rate exhibits consistent trends between theoretical calculation, numerical simulation and experimental value, with a maximum discrepancy of 8.9%. This validates the accuracy of both the theoretical model and numerical simulation. As the deformation angle of the removable panel increases, the sealing gap gradually widens, resulting in a compromised sealing effect. Moreover, the leakage rate in the central region of the sealing area is lower compared to that at both ends.

The leakage of the ceramic wafer seal structure under the removable panel with different deformation angles can be monitored based on Reynolds equation. The pseudo-transient numerical calculation method can be used to determine the leakage value of the micro-state ceramic wafer seal structure. These research findings provide a theoretical foundation and numerical investigation approach for studying ceramic wafer seal structures.

Planning for underground spaces has become an effective way to use central areas in cities given the steady economic growth in China. The development of underground spaces in mountainous cities has satisfied the needs of the diversification of the city commercial areas and pedestrian movement. Safety issues exist because these underground spaces were originally used for civil air defense. This study was based on the underground commercial street in Chongqing, which is a typical mountainous city. Based on the results of combined fieldwork and survey, this paper summarized current safety issues, which include the not-fully-open exit, the imbalanced exit location, blocked evacuation routes, and the poor awareness of the potential safety issues. This paper proposed a framework of the safety factors for the underground space and synopsized prevention strategies that are specific to potential disasters in the underground environment. The framework comprises ensuring that the exits are fully open, the underground corridors are kept unblocked, the open space on the street is increased for disaster prevention, and equipment security is maintained and managed. At last, This paper summarized disaster prevention strategies, which include ensuring unimpeded exits, balancing the locations of the exits, avoiding blocks, increasing the disaster prevention square area in the underground space, maintaining and managing the security of the equipment.

The purpose of this paper is to investigate the dynamic responses of a spur gear pair with unloaded static transmission error (STE) excitation numerically and experimentally and the influences of the system factors including mesh stiffness, error excitation and torque on the dynamic transmission error (DTE).

A simple lumped parameters dynamic model of a gear pair considering time-varying mesh stiffness, backlash and unloaded STE excitation is developed. The STE is calculated from the measured tooth profile deviation under the unloaded condition. A four-square gear test rig is designed to measure and analyze the DTE and vibration responses of the gear pair. The dynamic responses of the gear transmission are studied numerically and experimentally.

The predicted numerical DTE matches well with the experimental results. When the real unloaded STE excitation without any approximation is used, the dynamic response is dominated by the mesh frequency and its high order harmonic components, which may not be result caused by the assembling error. The sub-harmonic and super-harmonic resonant behaviors are excited because of the high order harmonic components of STE. It will not certainly prevent the separations of mesh teeth when the gear pair is under the condition of high speed and heavy load.

This study helps to improve the modeling method of the dynamic analysis of spur gear transmission and provide some reference for the understanding of the influence of mesh stiffness, STE excitation and system torque on the vibration behaviors.

While existing research has explored the association between supervisor support and turnover intention among construction workers, there is a notable gap in the literature concerning the potential mediating role of work engagement in elucidating this relationship, warranting further investigation. The paper, hence, aims to examine the mediating role of work engagement in the relationship between supervisor support and turnover intention among construction workers.

Based on the quantitative research method, the hypothesis was tested. The data were collected from 144 construction professionals using a structured questionnaire. Observed variables were tested using confirmatory factor analysis, and the mediating role relationship was validated using hierarchical regression.

The outcome of this study shows a significant positive impact of work engagement and supervisor support on employee turnover intention. The study further showed that work engagement plays a mediating role in the connection between supervisory support and the intention to turnover and improve project and business performance. Turnover intention, on the other hand, negatively affects project and organizational performance.

By enhancing employee work engagement and perceptions of supervisor support, the findings of this study may aid construction organizations in making better judgments regarding the likelihood of employee turnover. The effectiveness of the project and the organization will likely be greatly impacted.

The results of this study provide supporting evidence and advance efforts at reducing employee turnover intention through work engagement and supervisor support in improving project and organizational performance.

This in vitro study aims to explore the effects of selective laser melting (SLM) process parameters on the accuracy of the intaglio surface of cobalt–chromium alloy (Co–Cr), commercially pure titanium (CP Ti) and titanium alloy (Ti–6Al–4V) maxillary removable partial denture (RPD) frameworks and optimize these process parameters.

Maxillary RPD framework specimens designed on a benchmark model were built. The process parameters, including contour scan speed and laser power, infill scan speed and laser power, hatch space, build orientation and metallic powder type, were arranged through the Taguchi design. Three-dimensional deviations of the clasps area, connector area and overall area of maxillary RPD frameworks were analyzed by using root mean square (RMS) as a metric. One-way analyses of variance with the above RMSs as the dependent variable were carried out (α = 0.05).

Maxillary RPD frameworks built horizontally had a more accurate intaglio surface than those built at other orientation angles; CP Ti or Ti–6Al–4V maxillary RPD frameworks had a more accurate intaglio surface than Co–Cr ones; the Maxillary RPD framework built with a higher infill scan speed and lower infill laser power had the more accurate intaglio surface than the one built with other levels of these two process parameters.

A novel benchmark model for evaluating the accuracy of the intaglio surface of maxillary RPD frameworks manufactured by SLM is proposed. The accuracy of the intaglio surface of maxillary RPD frameworks can be improved by adjusting SLM process parameters. The optimal setting of process parameters concerning the accuracy of the intaglio surface of maxillary RPD frameworks was given.