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This paper proposes an adaptive scheme of designing sliding mode control (SMC) for affine class of multi-input multi-output (MIMO) nonlinear systems with uncertainty in the systems dynamics and control distribution gain. The proposed adaptive SMC does not require any a priori knowledge of the uncertainty bounds and therefore offers significant advantages over the non-adaptive schemes of SMC design. The closed loop stability conditions are derived based on Lyapunov theory. The effectiveness of the proposed approach is demonstrated via simulations considering an example of a two-link robot manipulator and has been found to be satisfactory. 相似文献
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Wu‐Yuin Hwang Nian‐Shing Chen Rustam Shadiev Jin‐Sing Li 《British journal of educational technology : journal of the Council for Educational Technology》2011,42(6):1016-1028
Previous studies have demonstrated that making annotations can be a meaningful and useful learning method that promote metacognition and enhance learning achievement. A web‐based annotation system, Virtual Pen (VPEN), which provides for the creation and review of annotations and homework solutions, has been developed to foster learning process among students. In order to explore the effects of reviewing annotations and homework solutions on learning achievement, a quasi‐experiment was conducted with VPEN in a math class over a period of 4 months. It was found that reviewing own text annotations has a significant influence on learning achievement; while on the contrary, reviewing peers' text annotations has no significant influence on learning achievement. Our results show that students gain more from reviewing their own annotations than from reviewing the annotations made by peers, a contrast which reveals that annotations hold additional meaning for their creators. Further investigation revealed that only the quantity of text annotations among all other variables can significantly predict students' learning achievement. This finding may suggest that text annotations play more important roles to learning achievement than other variables, like homework. The reason is because text annotations are created by learners actively on voluntary base whereas homework is usually assigned by the teachers. Based on our findings, we suggest that teachers may consider incorporating learning activities that can foster metacognitive development into the learning process, like making annotations, solving homework and reviewing them, whereas peer learning should be encouraged only for reviewing the homework solutions of their peers with good learning achievement. 相似文献
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Derwin K. C. Chan Alfred Sing Yeung Lee Duncan J. Macfarlane Martin S. Hagger Kyra Hamilton 《Journal of sports sciences》2020,38(14):1666-1673
ABSTRACT Two studies were employed to test the reliability and validity of the Swimming Competence Questionnaire (SCQ) among primary school children. Study 1 was a cross-sectional survey in 4959 primary school children. Study 2 was a pre-post-test quasi-experiment among 1609 primary school children who underwent a 20-lesson learn-to-swim programme. In Study 1, exploratory structural equation modelling revealed excellent goodness-of-fit and scale reliability for a two-factor model comprising distance and skill factors, which supported the construct and convergent validity. SCQ scores were significantly and positively correlated with swimming outcomes (i.e., self-efficacy, intention, swimming frequency), which supported SCQ’s concurrent and criterion validity. Average variance extracted for the SCQ factors exceeded cut-off criteria supporting discriminant validity. In Study 2, pre-test SCQ scores correlated significantly and positively with the SCQ scores, self-efficacy, intention, and swimming frequency at post-test, which supported SCQ’s test-retest reliability and predictive validity. Positive intraclass correlation between SCQ scores and coach ratings at post-test provided evidence for SCQ’s inter-rater reliability. SCQ scores significantly improved at post-test, which supported SCQ’s ecological validity. In conclusion, findings indicate that the SCQ is a valid and reliable measure to assess primary school children’s swimming competence, in terms of swimming distance and basic water survival skills. 相似文献
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Li Pei-Jung Hong Huang-Yao Chai Ching Sing Tsai Chin-Chung Lin Pei-Yi 《Research in Science Education》2020,50(5):2035-2053
Research in Science Education - The aim of this study was to investigate whether and how engaging with a computer-supported collaborative knowledge-building environment helps students to develop a... 相似文献
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Yin Hong Cheah Ching Sing Chai Yancy Toh 《Research in Science & Technological Education》2019,37(2):147-167
Background: Professional learning communities are increasingly recognized for their significance in building teachers’ competencies for educational reform. However, the knowledge development cycle of technological pedagogical content knowledge (TPACK) through multiple professional learning communities is not well researched.
Purpose: This qualitative case study investigates a primary science teacher’s TPACK development in the context of two interdependent learning spaces: a joint-school and a within-school professional learning community. The school’s organizational and sociocultural influences on teacher learning are also examined.
Participant: Teacher Sean (pseudonym) embarked on a science innovation project after two years of teaching in a Singapore mainstream school. He was tasked to integrate mobile-based inquiry learning and visible thinking pedagogical approaches, and to pilot the designed lessons for a primary three class.
Design and methods: A case-study approach involving multiple sources of data with cultural historical activity theory as the analytical lens was employed, to unpack the complementary and contradictory interactions across different interrelated activity systems. The purpose was to understand the (mis)alignments within and between the two professional learning communities.
Results: The findings indicate that Sean’s (subject) learning from the joint-school professional learning community to the within-school professional learning community faced multiple tensions that hindered his TPACK development (object). He faced difficulty in manipulating tools (technology and visible thinking routines) to translate the joint-school co-designed lessons into classroom implementation. Additionally, the volatility of the school’s organizational routines (rules) and the lack of communicative leader–teacher partnership (division of labor) did not afford sufficient infrastructure or instructional support.
Conclusions: Interactions between the teacher’s personal and contextual factors inhibited the designed TPACK from being implemented successfully. For ambitious pedagogical undertakings as illustrated in this case, more perceptive and synergistic organizational design thinking is needed to support beginning teachers’ TPACK development. 相似文献
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Catalina Sau Man Ng Wenyu Chai Hung Kit Fok Sing Pui Chan Ho Cheong Lam 《Journal of Early Childhood Teacher Education》2020,41(3):284-305
ABSTRACT Teaching Chinese to second language learners is a challenge for preschool teachers in Hong Kong so effective teacher professional development programmes are urgently needed to enhance their knowledge and skills. An Integrative Model Teacher Professional Development Programme which incorporates three theoretical underpinnings (i.e., culturally responsive teaching, meaningful and pleasurable learning, and effective teaching of Chinese as a second language) is designed to equip preschool teachers with knowledge, skills, and awareness in teaching Chinese to ethnic minority students. Through qualitative interviews with 15 in-service preschool teachers who joined the Programme, teachers’ perceptions and changes in three theoretical areas of teaching Chinese to ethnic minority students were explored. Particularly, teachers increased their awareness of ethnic minority cultures, developed empathy with ethnic minority children and their families, gained knowledge of implementing culturally responsive teaching and meaningful and pleasurable learning of Chinese. The role of teacher sharing in effective professional development was highlighted. 相似文献
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The present paper proposes two new schemes of sensor fault estimation for a class of nonlinear systems and investigates their performances by applying these to satellite control systems. Both of the schemes essentially transform the original system into two subsystems (subsystems 1 and 2), where subsystem-1 includes the effects of system uncertainties, but is free from sensor faults and subsystem-2 has sensor faults but without any uncertainties. Sensor faults in subsystem-2 are treated as actuator faults by using integral observer based approach. The effects of system uncertainties in subsystem-1 can be completely eliminated by a sliding mode observer (SMO). In the first scheme, the sensor faults present in subsystem-2 are estimated with arbitrary accuracy using a SMO. In the second scheme, the sensor faults are estimated by designing an adaptive observer (AO). The sufficient condition of stability of the proposed schemes has been derived and expressed as a linear matrix inequality (LMI) optimization problem and the design parameters of the observers are determined by using LMI techniques. The effectiveness of the schemes in estimating sensor faults is illustrated by considering an example of a satellite control system. The results of the simulation demonstrate that the proposed schemes can successfully estimate sensor faults even in the presence of system uncertainties. 相似文献
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Researchers state that teachers in different contexts reported different technological pedagogical content knowledge (TPACK). This phenomenon may partially be explained by cultural differences. Based on this consideration, the development and validation of the Chinese pre-service teachers’ technological pedagogical content knowledge (CTPCK) scale is described in this article. The sample was split into two subsamples on random basis (n1 = 229, n2 = 207) for the purpose of conducting (1) exploratory factor analysis (EFA) and (2) confirmatory factor analysis (CFA), respectively. After the EFA, the CTPCK scale excluded six items and included eight factors with 42 items. Reliability and correlations were discussed. The findings revealed that the CTPCK scale was a valid and reliable instrument for measuring the TPACK of Chinese pre-service teachers’ knowledge with or without linking educational technology. 相似文献
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Body donation is important for medical education and academic research. However, it is relatively rare in Hong Kong when compared with many Western countries. Comprehensive research has been performed on the motivation for body donation in Western countries; however, there is still insufficient research on body donation in Hong Kong to provide information on how to increase the body‐donation rate. To understand the factors involved in the decision to donate one's body, the authors interviewed a registered donor and the daughter of another donor in Hong Kong. The authors interpreted the information collected in light of the available published reports, which mostly focus on body donation in Western countries. Despite the consistency of some demographic factors and motivations between the participants in our study and those investigated in the published reports from Western countries, there are differences in education level and socioeconomic status between the donors in our study and those from Western studies. The authors also suggest that Confucianism and Buddhism in Chinese culture may motivate potential body donors in Hong Kong. Other important factors that influence the body‐donation decision may include family members' body donation, registration as organ donors, and good doctor–patient relationships. Although case report studies have their limitations, this study allows us to explore the complexity of events and establish the interconnectivity of factors involved in body donation, which could not be achieved in previous survey‐based studies. © 2012 American Association of Anatomists. 相似文献