Background: This review and meta-analysis aimed to evaluate the effects of high-intensity interval training (HIIT) on cardiorespiratory fitness, body composition, physical fitness, and health-related outcomes in older adults. Methods: Four electronic databases (PubMed, Scopus, Medline, and Web of Science) were searched (until Oct 2019) for randomized trials comparing the effect of HIIT on physical fitness, metabolic parameters, and cardiorespiratory fitness in older adults. The Cochrane risk of bias assessment tool was used to evaluate the methodological quality of the included studies; Stata 14.0 software was used for statistical analysis.Results: HIIT significantly improved the maximum rate of oxygen consumption (VO 2max ) compared with a moderate-intensity continuous training (MICT) protocol (HIIT vs. MICT: weighted mean difference = 2.04, 95% confidence interval: 1.01-3.07, p < 0.001). Additional subgroup analyses determined that training periods > 12 wks, training frequencies of 2 sessions/wk, session lengths of 40 min, 6 sets and repetitions, training times per repetition of > 60 s, and rest times of < 90 s are more effective for VO 2max . Conclusions:This systematic review and meta-analysis showed that HIIT induces favorable adaptions in cardiorespiratory fitness, physical fitness, muscle power, cardiac contractile function, and citrate synthase activities in older individuals which may help to maintain aerobic fitness and slow down the process of sarcopenia.
In order to achieve precise speed control for cutter suction dredger cutter motor, the controller should adapt well to uncertainties, such as geological environment, water flow, mechanical disturbance, etc. It makes the design of cutter motor controller always a hard work. This paper proposes an active disturbance rejection controller (ADRC) approach for cutter suction dredger cutter motor variable frequency drive system. Firstly, the LabVIEW platform was established by virtual instrument technology, which collected operating data of cutter motor in fundamental wave and total harmonic distortion (THD). Then cutter motor motion mathematic model was built and the ADRC design method was introduced. Lastly, the simulation results in the cutter velocity control and disturbance environments were done. The results show that the ADRC controller has strong robustness, and the precise speed control can be implemented.
With the rapid development of economic and construction industry, light-weight steel structural system is widely used in the modern building construction. While, the light-weight steel structures are more sensitive under the effect of snow load than the other structure systems according to the data from the large amount of accidents of steel structure failures, which indicated the necessary and urged us to focus on the impact of snow on the light-weight steel structures. This paper introduces the current research situation and analyzes the method of snow load determination on gable frames in the load code of different countries, and provides some suggestions on the snow load design of light-weight steel structures finally.
The wind tunnel tests of some typical large roofs, including a saddle roof, pitched roof and domes, are carried out with various terrains which cover suburban and urban exposures. The wind pressure data of roofs are obtained by using the synchronous multi-pressure scanning technique. The wind pressure coefficient and local shape factors of the wind load was investigated. The effects of various terrains on wind pressures of roofs are discussed. From the results, we can see mean pressures of these roofs exposed to the mean pressures exposed to the suburban terrain are 2 or 3 times those exposed to the urban terrain. And the terrains are no directly influence to the wind pressure shape factors.
Snow load is very important for the design of the large span roof structures in the cold region. The determine of the snow loads are influenced by many factors, such as wind, shape of the roof , terrain categories and so on, therefore comprehensive consideration of the transport and drift by the strong wind for design of the roof is very complex. Compared with other countries load codes, the China load code don’t detailed consider wind and snow interaction effect, the method of snow load for design has some further improved terms.
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