This paper focuses on the problem of adaptive tracking quantized control for a class of interconnected pure feedback time delay nonlinear systems. To satisfy the requirement of prescribed performance on the output tracking error, a novel asymmetric tangent barrier Lyapunov function is developed. The decentralized adaptive controller is designed via backstepping method. To deal with the uncertain interconnected nonlinear functions, we design a new virtual control input in the first step. Instead of estimating the bound of each unknown function, we use the adaptive method to estimate the bound of the composite function which is composed of the unknown functions. Thus the over parameterization problem is avoided. It is proved that the output of each subsystem satisfies the prescribed performance requirement and other state variables are bounded. Finally, the simulations are performed and the results verify the effectiveness of the proposed method. 相似文献
This paper investigates the prominence of rationalism in the major Western pedagogical theories of Plato, Rousseau, and Dewey, all of whom conceptualize formal teaching, as the inculcation of rationality in individual learners. After each of their theories has been described, the argument turns against the tradition of pedagogical rationalism to question what happens in the education of artists, quasi-artists, and creative designers. The answer given is that imagination must be paramount and strongly encouraged in the education of such students, despite the problematic fact that imagination – seeing the truth – cannot be taught the way that rationality can, relying instead on the analysis of successful works of art and design as exemplary and allowing students to freely pursue their own individual inspirations. 相似文献
Sports injuries are common among baseball players and may result in abnormal movement patterns, increased risks of future injury, and unsatisfactory performance. The Functional Movement Screen (FMS?) has been developed to detect abnormal functional movement patterns and can be used for predicting risks of sports injury. However, whether FMS? scores are associated with athletic performance remains unclear. The goal of this study was to determine the association between functional movements and athletic performance in elite baseball players. Core stability, muscular strength and flexibility of the lower extremities, and FMS?, as well as athletic performance in sprinting, agility, and balance tests were assessed in 52 male collegiate Division I baseball players placed into two groups based on FMS? scores. The high-scoring group demonstrated better athletic performance than the low-scoring group, with a shorter duration of the agility test. No group differences were found in core stability, muscular strength, or muscle flexibility, except for rectus femoris flexibility. Thus, the FMS? score is associated with sprinting and agility performance in elite baseball players. These findings indicate that the FMS? may have a role in predicting athletic performance and thereby help determine the goals of training regimens or return-to-play strategies. 相似文献
In the present study, we investigated the effect of a long-term mountain expedition on glucose tolerance and insulin action. Twelve registered mountaineers ages 31 years (SD = 1.1) participated in a 25-day expedition at a 2,200-3,800-m altitude with an average duration of 8 hr per day. Arterial oxygen saturation (SaO2) was substantially reduced during hiking. Glucose tolerance and insulin responses were measured prior to and twice during the expedition period. Maximal oxygen consumption increased from 43.0 +/- 2.7 to 49.1 +/- 2.2 mL/kg/min. Percentage of body fat decreased from 19.4 +/- 6.8% to 16.9 +/- 5.9%. The area under the curves for insulin and glucose during the oral glucose tolerance test were also reduced in Days 3 and 25. The present study demonstrated that altitude hiking activity is an effective lifestyle intervention to improve insulin action. 相似文献
The present study was an attempt to help us reveal the characteristics and complexity of today’s first-time online students in a higher education setting. Data were collected from undergraduate and graduate students enrolled in fully online courses for the first time during spring semester in the 2016–2017 academic year at a Southern university in the United States. Primarily, path analysis was conducted to investigate the impacts of flexible thinking, mindsets, and self-efficacy on the 254 first-time online students’ online learning engagement. The results of the path analysis supported six out of the eight hypotheses and all standardized path coefficients have values between 0.14 and 0.31. In conclusion, growth mindset and learning self-efficacy appear to be important variables for first-time online students and have a positive relation to online engagement. The practical implications and future research are discussed.