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ObjectiveThe purpose of this paper is to study the effects of cavitation models on the simulation of full-scale propeller cavitation. MethodsThe minimum rotational speed of the propeller required for cavitation is predicted by the Bernoulli equation, and the propeller's cavitation condition is observed by full-scale experiment. After determining the boundary layer mesh thickness and establishing the hydrodynamic model, meshes are generated. In the numerical simulation, the turbulence model is selected from either the standard \begin{document}$k - \varepsilon $\end{document} model or Realizable \begin{document}$k - \varepsilon $\end{document} model, and the cavitation model is selected from either the Schnerr−Sauer (S−S) model or the Zwart−Gerber−Belamri (ZGB) model. The maximum gas volume fraction on the surface of the propeller is tracked and recorded. In the meantime, the reliability of the numerical simulation is evaluated by observing the gas distribution on the surface of the propeller. And the simulation accuracy of the related models is compared. ResultsThe simulation results show that compared with the standard \begin{document}$k - \varepsilon $\end{document} turbulence model, the cavitation region obtained with the Realizable \begin{document}$k - \varepsilon $\end{document} model is significantly more consistent with the experimental results. By monitoring the maximum gas volume fraction on propeller's surface, it is found that the choice of turbulence model has little effect on the cavitation intensity, and the cavitation intensity obtained by S−S model is significantly higher than that obtained by the ZGB model. ConclusionsThis study shows that the turbulence model has a great influence on the area of the cavitation region, and cavitation models have a great influence on cavitation intensity. In terms of the simulation of propeller cavitation, the accuracy of the Realizable \begin{document}$k - \varepsilon $\end{document} model is higher than that of the standard \begin{document}$k - \varepsilon $\end{document} model.

ObjectivesThis study aims to carry out systematic research on the hydrodynamic performance of a small unmanned catamaran. MethodsBased on STAR-CCM+ numerical simulation software, the hydrodynamic performance of a small unmanned catamaran in a hydrostatic state and self-propelled state under different Froude (Fr) numbers is numerically simulated. The unsteady RANSE model is selected and the Dynamic Fluid Body Interaction (DFBI) model and overset grid function are used to simulate the trim and heave of the catamaran. A body-force propeller is used to replace the propeller effect. The empirical formula of the friction resistance coefficient is used to verify the simulation results of the hydrostatic state. The self-propelled experimental results are then compared to the simulation results of the self-propelled state to verify the accuracy of the simulation results. ResultsWhen the propeller speed is 3 000 r/min, the difference in total resistance between the self-propelled and hydrostatic states of the small unmanned catamaran is 21.099%. Under different propeller rotation speeds, the relative errors of the thrust between the simulation and experimental results of the self-propelled catamaran is less than 10%. ConclusionsThe comparison between the simulation results and experimental results verifies the reliability of the simulation. The hydrodynamic performance of the self-propelled ship hull studied by the volume method is quite different from that under hydrostatic conditions. The numerical method can provide valuable references for further predicting the hydrodynamic performance of small unmanned catamarans.

In this study, cellulose films loaded with different concentrations (0%, 0.1%, 0.5% and 1%) of curcumin (C-Cux-F) having good mechanical properties, water resistance, photosensitive antibacterial properties, and high oxygen-barrier performance were successfully prepared. Due to its strong interaction with the cellulose chain, curcumin could significantly improve the mechanical properties and water resistance of cellulose film. The doping level of curcumin significantly affected the oxygen permeability of cellulose film (P < 0.05). The oxygen permeability of the film gradually decreased with the increase in curcumin level. The oxygen permeability of the films loaded with 0%, 0.1%, 0.5%, and 1% curcumin was approximately (29.71 ± 1.66), (4.79 ± 0.13), (3.52 ± 0.45), and (0.90 ± 0.09) cm3/(m2·d) at room temperature (23 ℃), respectively. The addition of curcumin in the range of 0% to 0.5% significantly reduced the moisture permeability of cellulose film due to the enhancement of intermolecular forces (P < 0.05). Curcumin-loaded cellulose film exhibited a good photosensitive antibacterial effect against S. aureus, which increased with the extension in light exposure time. This is probably ascribed to the fact that photosensitization of curcumin generates singlet oxygen. After white light exposure for 10 and 20 min at an intensity of 60 mW/cm2, the inhibitory activity of 1% curcumin-loaded cellulose film (C-Cu1-F) against S. aureus was (61.00 ± 1.73)% and (91.67 ± 1.53)% , respectively. In the preservation of fresh chilled pork, C-Cu1-F could significantly inhibit the production of total volatile basic nitrogen (TVB-N), and reduce the total bacterial count (P < 0.05), implying a significant inhibitory effect on the growth of microorganisms and the production of biogenic amines. Therefore, curcumin-loaded cellulose film not only showed excellent mechanical and antibacterial properties, but also had a preservation effect on fresh pork.

Background In recent years, there has been a noticeable increase in the prevalence of polypharmacy among the older population, leading to a rise in the number of related studies. As a result, a stage analysis of its development is crucial. Objective To analyze the research trends and cutting-edge topics in the field of polypharmacy in the elderly from 2003 to 2022. Methods The Science Citation Index Expanded (SCI-E) and Social Sciences Citation Index (SSCI) subsets of the Web of Science Core Collection database were searched for articles and reviews about polypharmacy in the elderly published in English between 2003 and 2022. VOSviewer (v.1.6.18) and CiteSpace (v.6.1.R6) were used for bibliometric analysis. Results A total of 3 987 articles were obtained, including 3 208 articles and 779 reviews. The global volume of publications has increased rapidly in the last 20 years, with the United States (1 097 articles, 27.51%) having the most publications in this field. The University of Sydney in Australia has been the most prolific institution, publishing 156 articles (3.91%), while Dr. Sarah N. Hilmer of this institution has been the most productive author with 67 publications (1.68%). Among the journals, Drugs & Aging (181 articles, 4.54%) has featured the highest number of publications related to polypharmacy in older people. The high-frequency keywords in the field included elderly, polypharmacy, prevalence, and risk, while the current emerging topics revolved around clinical outcomes and public health issues about polypharmacy in the elderly. Conclusion Over the past two decades, the field of polypharmacy among older people has experienced rapid progress, characterized by an increasing number of publications with the United States as the largest contributor. Research topics have primarily focused on the prevalence and risks associated with polypharmacy among older people, while future studies are expected to focus more on the associated clinical outcomes and public health issues.