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In this paper, we develop two new model reference adaptive control (MRAC) schemes for a class of nonlinear dynamic systems that is robust with respect to an uncertain state (output) dependent nonlinear perturbations and/or external disturbances with unknown bounds. The design is based on a controller parametrization with an adaptive integral action. Two types of adaptive controllers are considered—the state feedback controller with a plant parameter identifier, and the output feedback controller with a linear observer. 相似文献
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This article examines the role elementary school children’s spontaneous metaphors play in learning science. The data consists
of tape recordings of about 25 h from five different schools. The material is analysed using a practical epistemology analysis
and by using Dewey’s ideas on the continuity and transformation of experience. The results show the rich and varied meanings
that children put into their spontaneous metaphors. Their metaphors deal with facts as well as norms and aesthetics in relation
to the science content taught and they influence learning both through what is made salient, as well as through their relations
to the children’s possibilities of proceeding with their undertakings. Often one and the same metaphor encompassed all these
cognitive, aesthetic and normative aspects at the same time. It is discussed how this rich meaning can be cultured in a productive
way, and how the children’s spontaneous metaphors, with all their relations, can be used to enhance conceptual learning and
also learning about the nature of metaphor use in science. Through their connection with various experiences of the children,
it is also shown how children’s spontaneous metaphors have the potential to enliven and humanise the subject. 相似文献
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A great deal of the ongoing discussion about environmental education and education for sustainable development has to do with democracy and deliberation. Here, for example, the normative approach has been challenged. As an alternative, there is sometimes a call for a curriculum and education that is characterized by democracy, participation, and pluralism. According to this call, it is still far from clear what it actually means to create education in terms of democracy. While the debate is lively, it is not always anchored in empirical research. In this study, three students in a classroom situation talk about resources and solidarity. Using analytical tools developed from a pragmatic base, the study tries to find a methodology to reveal how people create political subjects while engaged in such a discourse. This is associated with the discussion about democracy in education, and the consequences these findings may have in respect of how education on environment and sustainable development can be staged in terms of freedom and pluralism. 相似文献
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Purpose: This study examines how different purposes can support teachers in their work with progressions as a part of a teaching sequences in science in primary school.
Design/Method: The study was carried out in two classes working with inquiry and the events that took place in the classroom were filmed. In the study, we have chosen to use the technical term proximate purposes for the student-oriented purposes, and ultimate purposes for the scientific purposes. Together, these two types of purposes form the organisational purposes for the classes. Proximate purposes work in such a way that students can use their language and relate to their experiences as ends-in-view. To examine how organising purposes can be used to analyse progressions, we discuss examples from two different lessons.
Result: The study shows the importance of proximate purposes working as ends-in-view and also demonstrates how the teacher and students may create continuity in teaching to enable progression as a part of a teaching sequence.
Conclusions: To create continuity, it was essential that the teacher scaffolded the students in ways which allowed the students to explicitly differentiate between what was relevant or not, about the proximate purposes in relation to the ultimate purpose. 相似文献
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This article studies content issues by examining teachers’ communicated socialization content. The value-laden socialization content constitutes the educational context for the teaching of integrated subject matter and has not yet been thoroughly studied empirically in environmental education research. The implications of the results can be fruitful in discussions about how educational traditions evolve, as well as discussions about the relationships between environmental education (EE) and education for sustainable development (ESD). In this study, ten upper secondary teachers are interviewed and their expressed socialization content is examined. Various qualitative positions regarding five important educational aspects can be described in terms of three selective traditions. To strengthen the validity of the socialization content found in this study, the students of the same teachers were interviewed regarding their experiences of the socialization content of these teachers’ teaching. This is reported in a supplementary article (Sund and Wickman 2011; Sund 2008). Together these three studies (this article; Sund and Wickman 2011; Sund 2008) work to establish and test a method of discerning qualitative aspects in socialization content. Although the amount of data is limited, the ambition has been to triangulate socialization content qualitatively from three different sources: a literature study, teacher interviews, and student interviews. 相似文献
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Per-Olof Erixon 《Scandinavian Journal of Educational Research》2018,62(6):865-883
This article concerns how teachers of Mother-Tongue Education (MTE) and pupils in Swedish secondary schools look upon and relate to the keyboard and screen and pen and paper, respectively, for writing in the context of MTE. The results showed that both teachers and pupils found that the computer on one side and the pen and paper on the other circumscribed different writing processes. Paper and pen offered greater resistance when writing than a computer. It was concluded that writing on a computer had been culturally appropriated in the MTE and represented the frame for both teachers and students from which they assessed the advantages and disadvantages of each technology, but also that paper and pen added a value of necessity rather than eccentricity for the pupils, in contrast to the teachers, in order to meet the requirements concerning grammar, longhand, and orthography. 相似文献
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Per-Olof Wickman 《International Journal of Science Education》2013,35(5):465-486
We examined how university students made generalizations when making morphological observations of insects. Five groups of two or three students working together were audio recorded. The results were analysed by an approach based on the work of Wittgenstein and on a pragmatic and sociocultural perspective. Results showed that students rarely made generalizations in terms of universal statements and they did not use induction or produced hypotheses for testing in an analytic philosophical sense. The few generalizations they made of this kind were taken from zoological authorities like textbooks or lectures. However, students used induction when in more familiar contexts. Moreover, when generalizations were analysed in the sense of Dewey, it became evident that students are fully capable of making generalizations by transferring meaning from one experience to another. The implications of these results for using induction and hypotheses testing in instruction are discussed. 相似文献
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Per Anderhag Patrik Emanuelsson Per-Olof Wickman Karim Mikael Hamza 《International Journal of Science Education》2013,35(18):3141-3160
It is commonly argued that socio-economic inequalities can explain many of the differences in achievement and participation in science education that have been reported among countries and among schools within a country. We addressed this issue by examining (a) the relationship between variables associated with socio-economic background and application frequencies to the Swedish Natural Science Programme (NSP) in upper secondary school and (b) whether there are lower secondary schools in Sweden that seem to compensate for these variables. Data from Statistics Sweden (SCB) covering the whole population of 106,483 ninth-grade students were used to calculate the probability for each student to apply to the NSP. Our results indicate that the variables, such as parental educational level and grades, have explanatory power, but with varying effect for different subpopulations of students. For example, grades in mathematics have a greater impact than grades in science for females' choice of the NSP. The opposite holds for male students. Out of 1,342 schools, 158 deviated significantly from predicted, that is, the students in these schools applied to the NSP in greater or lesser extent than expected. The number of deviating schools is greater than predicted by pure random variation. This suggests that variables of socio-economic background are only a partial explanation of the application frequencies, and that the deviation needs to be investigated further. Our findings suggest that in order to understand why schools deviate positively and so compensate for the socio-economic background of their students, we need to study their practices more closely. 相似文献