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Two stress regime‐dependent creep constitutive equations, that is, two‐regime Norton (2RN) model and Sin‐hyperbolic (Sinh) model, are adopted to numerically investigate the influence of constitutive equation and friction on the measurement of steady‐state creep strain rate based on five types small specimens. Results show that the influence of constitutive equation and friction depends strongly on the type of small specimen. A measurement error of more than 19 times may occur if the 2RN model is used, while the use of the Sinh model is able to generate a consistently lower measurement error. Of all small specimens, the cantilever beam testing (CaBT) is revealed to exhibit the best comprehensive performance in terms of measurement error and response to friction. To validate numerical findings, creep tests on the CaBT specimen of P91 steel are conducted at 600°C. Finally, recommendations on the choice of small specimen for obtaining creep strain rate are made. Highlights: Sinh model is better in describing stress regime‐dependent creep behavior.Influence of friction is strongly dependent on the type of small specimen.Small cantilever beam testing has the best comprehensive performance.Attention should be paid to selecting the constitutive equation and specimen type. [ABSTRACT FROM AUTHOR]

Objective To systematically evaluate the oral health status of senile dementia patients. Methods The CNKI, Wanfang, CBM, PubMed, Embase and Web of Science databases were searched online. Literature on the oral health status of Alzheimer′s patients published at home and abroad was collected. The search period extended to De⁃ cember 2018. Revman 5.3 software was used to perform the meta⁃analysis of homogeneous research. Results Ten stud⁃ ies satisfied the eligibility criteria. The meta⁃analysis revealed that older people with dementia had fewer remaining nat⁃ ural teeth [MD＝⁃3.22 (95% CI ⁃5.59, ⁃0.85)] and more decayed missing filled teeth [MD＝3.36 (95% CI 0.80, 5.92)] than the healthy control group (P < 0.05). The plaque index [MD＝0.86 (95% CI 0.45, 1.28)], percentage bleeding on probing [MD＝16.60 (95% CI 9.81, 23.39)], probing depth [MD＝0.68 (95% CI 0.03, 1.34)], and clinical attachment loss [MD＝1.13 (95% CI 0.38, 1.88)] were significantly higher in older people with dementia than in the healthy control group (P < 0.05). Conclusion The dental and periodontal health status of Alzheimer′s patients is worse than that of healthy controls. Thus, the former group needs special oral care and treatment.

This study proposes a non-invasive method for estimating the pulsating flow and pressure difference, which uses the blood pump estimation model based on a multi-layer perceptron to calculate the flow and pressure difference under pulsating conditions. The model takes 11 parameters such as the rotational speed, power, and pulsation waveform of the blood pump as the input and uses the pressure difference and flow as the output. The experimental results of 119,590 sample data show that the flow error of the training set of the blood pump estimation model is 0.14 l/min and the pressure difference error is 7.50 mmHg; the flow error of the test set is 0.14 l/min and the pressure difference error is 7.50 mmHg. Compared with the traditional flow and pressure prediction method, this method has higher precision, which will provide a certain technical accumulation for accurately estimating the flow and pressure difference of the blood pump in the pulsating conditions.

In view of the problem that transmission performance of wireless power transmission system is deteriorated with change of coupling distance in over-coupled region and in order to achieve the maximum power output with fixed-frequency mode, a new method was proposed which achieves impedance dynamic compensation by changing the generalized coupled factor variable of two planar spiral coils in primary coil circuit, and the mechanism of impedance dynamic compensation strategy were studied. Firstly, taking E-type double-tube LLC resonant inverter circuit as research object, circuit theory was used to establish model and analyze system output power, transmission efficiency and interaction mechanism of characteristic parameters; the variation law of system output power curve and transmission efficiency curve of the system were obtained, and it is concluded that the generalized coupling factor between two compensation coils has a direct impact on the system output power curve and transmission efficiency curve. Secondly, the mechanism of impedance dynamic compensation strategy was revealed, and an implementation program with fixed-frequency mode was presented. In the end, the correctness and validity of the theoretical analysis were verified by experiments.

Online learning has attracted attention from academics and educators for several decades. Online learning plays a significant role in many educational institutions, including higher vocational hospitality colleges, especially during the COVID-19 outbreak. However, students' learning experience of online and face-to-face higher vocational hospitality courses is scarcely understood. To fill this research gap, a higher vocational college in China is selected as a case study to conduct a comparative study. Results show that students scored higher in face-to-face hospitality course learning experience than in online courses. Theoretical and practical implications are provided accordingly. [ABSTRACT FROM AUTHOR]

In view of problems that transmission performance of three-coil wireless power transmission system would change with moving of relay coil, coupling mechanism of three-coil wireless power transmission system was researched. An equivalent circuit model of the wireless power transmission system was built which is based on three-coil structure, and basic characteristic formula of output power gain and transmission efficiency were deduced. Interaction mechanism of the output power gain, transmission efficiency and characteristic parameters were analyzed, and laws of the output power gain and transmission efficiency of the system were obtained. The wireless power transmission experiment system was developed which verifies correctness of the theoretical analysis.

For the problem that output power of a single inverter in wireless power transmission system could not satisfy large power requirement, power combination mechanics of wireless power transmission system based on multi inverters was researched. An equivalent circuit model of wireless power transmission system was built which was based on power combination topology of two inverters, and laws of output power and transfer efficiency of the system were obtained. The research results are as following. Output power and transfer efficiency of the system are shared by each branch inverter, and distributed in each branch complementarily because of different power driving ability of each branch. System characteristics of wireless power transmission system based on power combination of multi inverters is identical with that of the system based on single inverter.