Study on age-related changes of knee flexor muscle strength in middle-aged and elderly people

Shengjie Liu,Chengfei Zhang,Lu Zhang 아시아건강운동학회 2019 Journal of Asian Society for Health & Exercise Vol.1 No.1

PURPOSE: To investigate the age-related changes of knee flexor muscle strength in middle-aged and elderly people aged 45-64 years in China; to study the effects of different physical exercise habits on the age-related changes of knee flexor muscle strength in middle-aged and elderly people. METHODS: The knee flexor muscle strength test was performed on the middle-aged and elderly people aged 45-64 by using the intelligent isometric muscle strength test system. The statistical analysis software spss21.0 was used for descriptive statistical analysis of the test data, age-related trend analysis, independent sample T-test analysis, analysis of variance and multiple comparisons were performed. Finally, regression analysis was used to analyze the influencing factors of age-related trends. RESULTS: It can be seen from Table 2 that there is a gender difference in the maximum muscle strength of the right and left lateral knee flexors, but the difference is not obvious. Among them, the average age of male middle-aged and older people is above 180N, and the females are all below 150N. The muscle strength of male middle-aged and older people is generally larger than that of female middle-aged and elderly. CONCLUSIONS: (1) there was gender difference in the maximum muscle strength of knee flexor in middle-aged and elderly people, but there was no difference between left and right (p<0.01). The gender difference shows that the mean muscle strength of the male is greater than that of the female, and the mean muscle strength of the male in each age group is about 1.5-2 times of that of the female corresponding age group, but the range of variation of the female muscle strength is more stable than that of the male (p<0.01). (2) The maximal muscle strength of the knee flexor of the male and female middle-aged groups showed a gradual decline in the overall age (p<0.01). And before the age of 60-64, the aging decline of female muscle strength is faster than that of male. Moreover, women showed a small upward trend in the 60-64 age group, but this phenomenon did not occur in male middle-aged people (p<0.01).

The One-persistent Multichannel CSMA Protocol with Monitoring Functions Based on Conflict Resolution Algorithm in WSN

Shengjie Zhou,Hongwei Ding,Yifan Zhao,Zhijun Yang,Qianlin Liu 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.1

In the Wireless Sensor Network, a new MAC protocol: one-persistent CSMA protocol with monitoring functions and multichannel mechanism for Wireless Sensor Network based on conflict resolution algorithm is proposed. Protocol from the system throughput, collision rate, better service quality for higher priority and other aspects improve the traditional CSMA system to perfect the controllability of the system, making the system more stable for the big data, better adapted to different business. The average cycle method is used to derive rigorous mathematical expressions of specific relevant parameters. Using MATLAB simulation tool for the accuracy of the agreement is demonstrated.

On Which Microphysical Time Scales to Use in Studies of Entrainment‐Mixing Mechanisms in Clouds

Lu, Chunsong,Liu, Yangang,Zhu, Bin,Yum, Seong Soo,Krueger, Steven K.,Qiu, Yujun,Niu, Shengjie,Luo, Shi American Geophysical Union 2018 Journal of Geophysical Research: Atmospheres Vol.123 No.7

<P>The commonly used time scales in entrainment-mixing studies are examined to seek the most appropriate one, based on aircraft observations of cumulus clouds from the RACORO campaign and numerical simulations with the Explicit Mixing Parcel Model. The time scales include the following: (evap), the time for droplet complete evaporation; (phase), the time for saturation ratio deficit (S) to reach 1/e of its initial value; (satu), the time for S to reach -0.5%; and (react), the time for complete droplet evaporation or S to reach -0.5%. It is found that the proper time scale to use depends on the specific objectives of entrainment-mixing studies. First, if the focus is on the variations of liquid water content (LWC) and S, then (react) for saturation, (satu) and (phase) are almost equivalently appropriate, because they all represent the rate of dry air reaching saturation or of LWC decrease. Second, if one focuses on the variations of droplet size and number concentration, (react) for complete evaporation and (evap) are proper because they characterize how fast droplets evaporate and whether number concentration decreases. Moreover, (react) for complete evaporation and (evap) are always positively correlated with homogeneous mixing degree (); thus, the two time scales, especially (evap), are recommended for developing parameterizations. However, and the other time scales can be negatively, positively, or not correlated, depending on the dominant factors of the entrained air (i.e., relative humidity or aerosols). Third, all time scales are proportional to each other under certain microphysical and thermodynamic conditions.</P>

Visualization of combustion performance and emission characteristics of a four-cylinder diesel engine at various inlet oxygen concentrations at part loads

Huaping Xu,Shengji Liu,Bifeng Yin,Hekun Jia,Shenghao Yu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6

Although exhaust gas recirculation (EGR) is a common way to suppress the nitrogen oxide (NO X ) emissions, it also brings some negative impact on soot emissions and the thermal efficiency in internal combustion engines. We investigated the effects of ambient oxygen concentrations on engine performance, combustion characteristics, and emissions using a four-cylinder diesel engine equipped with an endoscopic visualization system. To estimate the flame temperature and soot distribution, we analyzed these images using a postprocessing program. Experimental results showed that the luminosity of flames in the images was degraded comparatively for the reduced oxygen concentration. Flame temperature distribution also showed similar behavior. As the oxygen concentration decreased, area of soot distribution significantly reduced at IMEP = 0.13 MPa, and only a slight decrease at IMEP = 0.3 MPa. But locally high soot concentration regions increased.

One-pot synthesis of electron-acceptor composite enables efficient fullerene-free ternary organic solar cells

Zhang, Jianyun,Liu, Wenrui,Chen, Shanshan,Xu, Shengjie,Yang, Changduk,Zhu, Xiaozhang The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.45

<P>An effective strategy of “synthesizing an electron-acceptor composite (ZITI-m) by one-pot reaction” to improve photovoltaic performance is proposed. The ZITI-m composite is synthesized by one-pot Knoevenagel reaction of ZIT-2CHO and a mixture of INCN-2F and I-a, from which asymmetrical ZITI-3F and symmetrical ZITI-4F are separated. J71:ZITI-m-based OSC shows the highest PCE of 13.65 ± 0.13% with remarkable PCE of 13.85% than those based on J71:ZITI-3F (12.97 ± 0.15%) and J71:ZITI-4F (13.02 ± 0.13%) blends. The effect of acceptor ratio in the composite on OPV performance indicates that all PCEs of composite system are higher than those of the materials based on pure acceptors with a broad composition tolerance, which is ascribed to the synergistic effect of the ternary blend system.</P>

Performance optimization of diesel engine fueled with diesel–jatropha curcas biodiesel blend using response surface methodology

Huaping Xu,Bifeng Yin,Shengji Liu,Hekun Jia 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8

The present work is aimed at unfolding the effect of fuel supply parameters such as Fuel injection pressure (FIP), Start of injection timing (SOI), Pilot-main injection intervals (PMII) on performance and emission characteristics of 20 % blend of Jatropha curcas biodiesel (J20) under light load operation of a diesel engine. The experiments were designed using design of experiments based on the fractional factorial design of Response surface methodology (RSM). Multiple regression models developed using RSM for measured responses like nitrogen oxides (NO X ), SOOT, hydrocarbon (HC), Brake specific fuel consumption (BSFC) and Brake thermal efficiency (BTE), were found to be statistically significant by Analysis of variance (ANOVA). Interactive effects among FIP, SOI and PMII were analyzed using response surface graphs that were fitted using developed RSM models. Optimization was performed using the desirability approach of the RSM for lesser emissions and BSFC simultaneously with superior BTE. A FIP of 134.11 MPa, SOI of 6.4 BTDC, and PMII of 5.8 CA were found to be optimal values for J20 in the test engine of 21 kW at 1800 rpm. The results of this study show that at optimal input parameters, the values of the NO X , SOOT, HC, BSFC and BTE with a high desirability of 96.7 % are 603.44 ppm, 0.037 FSN, 12.73 ppm, 233.26 g/kW h and 37.31 %, respectively.

Review of Research on Yoga Intervention and Health Promotion Based on Citespace - A Comparative Analysis between China and the United States

Chengfei Zhang,Junxia Zhang,Jianjiao Su,Shengjie Liu,Lu Zhang 아시아건강운동학회 2019 Journal of Asian Society for Health & Exercise Vol.1 No.2

In order to research and inquire the development of yoga intervention and health promotion deeply in China and to find out the differences between China and the United States. This research uses Citespace software to analyze the evolution vein, research hotspots, and module knowledge groups of yoga intervention and health promotion research in China and the United States from three aspects: basic information, keywords, and co-citation networks. On this basis, the research theme, formation and development trend of each module knowledge group is analyzed, and the comparative analysis of the research concept, research content and research trend of each module group is carried out. The results suggest that the United States is significantly better than China in terms of total number of publications, trends in publications, volume of journals, and authors" related publications. Plenty of differences do exist in research models, research hotspots, and research continuity between China and the United States. The comparison shows that the United States focuses on the medical value of yoga, while China focuses on the value of yoga exercise. The differences in research concepts between China and the United States have led to differences in research approach and development trends between China and the United States. This study has played a positive role in clarifying the development status of yoga intervention and health promotion in China which could accelerate future research.