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Eduardo V.L. Nunes Alessandro J. Peixoto Tiago Roux Oliveira Liu Hsu 《Journal of The Franklin Institute》2014
This paper presents a solution to the problem of global exact output tracking for uncertain MIMO (multiple-input–multiple-output) linear plants with non-uniform arbitrary relative degree using output feedback sliding mode control. The key idea to overcome the relative degree obstacle is to generalize our previous hybrid estimation scheme to a multivariable version by combining, through switching, a standard linear lead filter with a non-linear one based on robust exact differentiators, achieving uniform global exponential practical stability and exact tracking. 相似文献
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Self-esteem and Academic Achievement Among Adolescents 总被引：1，自引：0，他引：1
The main purpose of this research is to analyse what strategies are pursued in order to protect self-esteem when it is threatened by a negative self-evaluation of school competence. Participants were 838 secondary-school students from the seventh to the ninth grades. Data were collected using Harter's Self-Perception Profile for Adolescents, together with a Scale of Attitudes towards School. Our results show that there are significant differences between the self-esteem enjoyed by successful and unsuccessful students in the seventh grade; such differences disappear in the eighth and ninth grades. They also reveal success-related differences in domain-specific self-evaluation. We also found that students with low levels of academic achievement attribute less importance to school-related areas and reveal less favourable attitudes towards school. We discuss these results in terms of Harter's self-esteem model and Robinson and Tayler's self-esteem protection model. 相似文献
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Joana Cadima Carla Peixoto Teresa Leal 《European Journal of Psychology of Education - EJPE》2014,29(1):139-158
The observation and assessment of quality of teacher–child interactions in elementary school settings are increasingly recognized as important; however, research is still very limited in European countries. In this study, we examined the quality of the interactions between teacher and children in first-grade classrooms in Portugal and the extent to which structural features at teacher-, classroom-, and school-level explained variation in this quality. One hundred fifteen classrooms participated in the study. Classrooms were observed through a standardized rating scale concerning emotional, organizational, and instructional support. Results indicated that the levels of emotional and organizational support in most classrooms were of moderate quality, but the levels of instructional support were low, suggesting that most observed activities did not encourage students’ higher-order thinking skills. An examination of the associations between teacher and classroom characteristics and the quality of teacher–child interactions indicated a small effect for teacher education. Teachers with an advanced degree were more likely to be more emotionally sensitive and to have better instructional interactions in the classroom. For school-level characteristics, findings showed that the classrooms in private and smaller schools were likely to provide higher levels of emotional, organizational, and instructional quality. The results suggest that focusing on the interactions between teacher and children can provide valuable information to enhance classroom quality. 相似文献
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Tiago Roux Oliveira Alessandro Jacoud Peixoto Liu Hsu 《Journal of The Franklin Institute》2012,349(4):1397-1415
This paper addresses the design of a sliding mode based extremum-seeking controller for a class of single-input–single-output (SISO) uncertain nonlinear systems with unmatched and state-dependent strong nonlinearities. We demonstrate that it is possible to achieve an arbitrarily small neighborhood of the desired optimal point using only output-feedback. The key idea is the combination of a periodic switching function with a norm state observer. As an important advantage, we show that the proposed scheme achieves extremum-seeking for all initial conditions, i.e., the real-time optimization algorithm has global convergence properties. An application to a simple nonderivative optimizer illustrates the viability of the proposed approach. 相似文献
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Higher education (HE) systems around the world have experienced profound structural changes, particularly since the late 1960s to early 1970s, essentially driven by the need to expand access to tertiary education. This has resulted in a diversity of HE institutions (HEI) with different roles, missions and statuses, as well as academic staff with diverse perspectives and motivations. The present study is based on a survey undertaken in Portugal by a trade union, which aimed to collect faculty perspectives on a proposed HE reform sent out for public discussion by the government. Questions addressed the reorganization of the HEI network, the internal restructuring of HEI, the funding system and the binary divide of HEI (universities and polytechnics). The survey results showed a disparity of faculty perspectives about the proposed reform, closely related to the diversity of HEI. Respondents from lower academic categories and from smaller HEI were more opposed to reorganizing the HEI network. This reorganization was more widely accepted by university staff, who were also more in favour of a binary system than were polytechnic respondents. Although there was general agreement about the need to change the funding system, polytechnic respondents were strongly against a funding differentiation between universities and polytechnics. Despite an overall reformist trend, the enthusiasm for reforms declined substantially when the questions had a direct reference to the respondent’s region or institution. It is argued that HE expansion has driven the diversification of HEI, leading to a range of perspectives about the HE system and the way it should be changed. These conclusions may contribute to insights into other HE systems around the world where institutional diversification has been sought by public policies. 相似文献
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Mata Lourdes Monteiro Vera Peixoto Francisco Santos Natalie Nóbrega Sanches Cristina Gomes Marta 《European Journal of Psychology of Education - EJPE》2022,37(2):391-415
Learning maths is challenging for many primary school students, and teachers must understand students’ learning and emotional processes specific to learning maths. The current research, grounded in control-value theory, focused on achievement emotions regarding maths. Primary school students (N?=?71) were studied with the primary objective of examining the longitudinal trajectories of achievement emotions of third graders over two years. The Portuguese Achievement Emotions Questionnaire for Elementary Students was administered biannually to assess enjoyment, anxiety, and boredom regarding maths. The results indicate that enjoyment decreased and boredom increased over time, revealing three emotional profiles: positive, negative and moderate. The positive profile showed the highest scores in maths achievement. Profile membership was moderately stable and became increasingly stable and structured. In examining the complexity of students’ emotional profiles and processes, the importance of understanding them to enhance educational support, development, and learning was highlighted.
相似文献8.
Francisco Peixoto Cristina Sanches Lourdes Mata Vera Monteiro 《European Journal of Psychology of Education - EJPE》2017,32(3):385-405
This study analyzes the relationships between cognitive appraisals, classroom and test emotions, and math achievement in a sample of 1219 Portuguese students from the 6th and 8th grades. Participants completed measures of perceived value, perceived competence, and seven math achievement emotions (boredom, hopelessness, anger, anxiety, enjoyment, pride, and relief) experienced in two different settings: classroom and tests. Math achievement was obtained from school records. Results showed significant associations between student competence and value appraisals, their emotional experiences in test and classroom situations, and their math achievement. However, when emotions were considered simultaneously in structural equation modeling, only anger in test situations and hopelessness were significant negative predictors of students’ math achievement. Hopelessness appears to play a particular role in the interplay between cognitive appraisals, emotions, and academic achievement as it is the only emotion that relates to math achievement both in test and classroom situations. Furthermore, findings also support the existence of differences in the relationships between cognitive appraisals and the achievement emotions students experience in these two settings. 相似文献
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Self-concept, self-esteem and academic achievement: strategies for maintaining self-esteem in students experiencing academic failure 总被引：2，自引：0，他引：2
Francisco Peixoto Leandro S. Almeida 《European Journal of Psychology of Education - EJPE》2010,25(2):157-175
Previous research into the relationship between self-esteem and academic achievement shows that despite differences in academic
self-evaluation, students’ global self-representations do not differ as a result of their grades at school. In this study,
we will analyse the strategies that underachievers used to maintain their self-esteem at an acceptable level. The participants
were 955 adolescents in the 7th, 9th and 11th grades at four secondary schools in Lisbon. Three hundred fifty-two of these
students had retaken a year at least once in their school careers, whilst 603 had never done so. We collected the data using
both a self-concept scale and a scale for evaluating attitudes towards school. Results show that self-esteem is maintained
through positive self-representations in non-academic facets of self-concept and/or by devaluing school-related competences.
They also show that younger students are less likely to maintain self-esteem by devaluing the school experience. 相似文献
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