Bending-torsional flutter of a cantilevered wing containing a tip mass and subjected to a transverse follower force

This paper is a study of the bending-torsional flutter of a cantilevered wing subjected to a follower force, and containing a lumped mass, at the free end. In addition, a distributed aerodynamic loading is introduced along the wing. This results in a set of nonself-adjoint differential equations with variable, complex coefficients whose solutions are obtainable only in series form. Using the Frobenius method, a direct procedure is employed which retains the exact expression of the Theodorsen function and the unknown coefficients are evaluated on a computer which numerically converge to any prescribed accuracy. It is found that, as a result of the interaction of the two sources of non-conservative loadings, the follower force reduces considerably the critical speed of flows in all cases studied. An increase in the tip mass, however, has a stabilizing influence. The effect of structural damping is also examined and it is shown that internal damping forces may have pronounced influences on the flutter speed of the system.     

Understanding and communicating climate change in metaphors

An analysis of students’ conceptions on climate change shows a great confusion on key aspects of global warming. Even after instruction students often hold conceptions that differ from scientists’ conceptions. Student’s conceptions on global warming were collected in a reanalysis of 24 studies on everyday concepts of global warming as well as in an own interview study with 35 18-year-old students from German grammar schools. Climate-scientists conceptions were analysed from textbooks and research reports in a literature study. All data were analysed by systematic metaphor analysis and qualitative content analysis. Experientialism as a theory of metaphor provided insight in the process of understanding. The analysis of conceptions by experientialism shows that students and scientists have different metaphorical conceptions of global warming – but both refer to the same schemata. These schemata in mind we categorised the conceptions of global warming. Hereby we identified different thinking patterns in students’ and scientists’ conceptions. Following the model of educational reconstruction we took the metaphorical conceptions as a starting point for the development of learning environments. By uncovering the – mostly unconsciously – employed schemata, we gave students access to their metaphorical conceptions and let them reflect on their mental models.     

A Professional Learning Experience for Pre‐service and In‐service Teachers and One Teacher Educator: reflections and lessons learned

Abstract

In this paper we reflect on our efforts during the 1992–93 academic school year to create a different type of teacher education experience — one based on active learning, and collegiality and mutuality. Drawing on a model for classroom‐based teacher development described by Thiessen (1992), we begin with an overview of how we worked to (a) improve the quality of learning for all participants; (b) create a supportive learning environment for all the stakeholders; (c) leant in the complex and changing situation of classroom life; (d) combine personally meaningful, educationally defensible and socially justifiable evaluation practices; and (e) engage in reflective, interactive and transformative experiences. After this we. describe tension we experienced, which resulted from a lack of shared vision among us and from our efforts to examine our own practice. We also explore how we tried to deal with the tension. We conclude with lessons learned from our experience which have led to new questions about teacher education reform.     

Understanding the Greenhouse Effect by Embodiment – Analysing and Using Students' and Scientists' Conceptual Resources

Over the last 20 years, science education studies have reported that there are very different understandings among students of science regarding the key aspects of climate change. We used the cognitive linguistic framework of experientialism to shed new light on this valuable pool of studies to identify the conceptual resources of understanding climate change. In our study, we interviewed 35 secondary school students on their understanding of the greenhouse effect and analysed the conceptions of climate scientists as drawn from textbooks and research reports. We analysed all data by metaphor analysis and qualitative content analysis to gain insight into students' and scientists' resources for understanding. In our analysis, we found that students and scientists refer to the same schemata to understand the greenhouse effect. We categorised their conceptions into three different principles the conceptions are based on: warming by more input, warming by less output, and warming by a new equilibrium. By interrelating students' and scientists' conceptions, we identified the students' learning demand: First, our students were afforded with experiences regarding the interactions of electromagnetic radiation and CO₂. Second, our students reflected about the experience-based schemata they use as source domains for metaphorical understanding of the greenhouse effect. By uncovering the—mostly unconscious—deployed schemata, we gave students access to their source domains. We implemented these teaching guidelines in interventions and evaluated them in teaching experiments to develop evidence-based and theory-guided learning activities on the greenhouse effect.     

A Comparison of Piaget's and Kohlberg's Theories and Tests for Moral Judgment

Abstract:R?rvik, H. 1980. A Comparison of Piaget's and Kohlberg's Theories and Tests for Moral Judgment. Scandinavian Journal of Educational Research 25,99‐124. Piaget's and Kohlberg's theories for moral judgment are compared. On the basis of this comparison, hypotheses are formulated regarding expected relationships between the tests constructed on the basis of the two theories. The empirical testing of these hypotheses indicates that there are marked similarities between Piaget's and Kohlberg's tests as to characteristics measured, power of discrimination between age levels, and in the stage placement of subjects.

The main differences between the tests seem to be that Piaget's test is most influenced by the personal relationship to other persons. Contrary to the impression given by the theorist himself, Kohlberg's test seems to a larger extent to measure the subjects’ norms and emotional reactions connected to inter‐nalization of norms. Moral behavior is more closely related to Kohlberg's measure.     

Konfigurierungskonzepte für DB-basierte technische Entwurfsanwendungen

Zusammenfassung  . Schwerpunkte einer Datenbank-Unterstützung von technischen Entwurfsanwendungen sind eine geeignete Ablaufkontrolle sowie ein geeignetes Datenmodell. Letzteres mu? Versionen komplexer Objekte verwalten k?nnen. Um aus der Gesamtmenge der in einer Datenbank enthaltenen Versionen konsistente Einheiten (Mengen ‚kompatibler’ Versionen) hervorheben zu k?nnen, werden geeignete Konfigurierungskonzepte ben?tigt. Dieses Papier gibt eine Klassifikation verschiedener DB-bezogener Konfigurierungsans?tze, bewertet diese und begründet damit die Wahl, die im Rahmen des Objekt- und Versionsdatenmodells OVM hinsichtlich des zu unterstützenden Konfigurierungskonzeptes getroffen wurde. Wir werden argumentieren, da? insbesondere die Flexibilit?t, die das gew?hlte Konzept sowohl hinsichtlich der Definition von Konfigurationstypen als auch hinsichtlich des Anlegens von Konfigurationen bietet, zu einer besseren Unterstützung von technischen Entwurfsanwendungen als in bestehenden objekt-orientierten Systemen führt. Eingegangen am 14. Oktober 1996/Angenommen am 27. Oktober 1997     

Core executive functions are selectively related to different facets of motor competence in preadolescent children

Background: Although accumulating evidence suggests that motor and cognitive development is interrelated, only a few studies have investigated links between executive function and motor control. Therefore, the present cross-sectional study examined the relationship between motor competences and core components of executive functioning, including inhibitory control, working memory and cognitive flexibility. Methods: In 89 preadolescent children, motor competences were assessed using the MOBAK-5 test battery. Additionally, all participants completed computer-based versions of the Flanker task, which included standard and switch blocks, and the 2-Back task. Results: Partial correlations (correcting for age, gender and body mass index) revealed that locomotor skills were associated with the adjusted hit-rate on the 2-Back task (r?=?0.34) whereas object control was linked with conflict score on the Flanker task (r?=??0.39). In contrast, there was no correlation between switch costs and motor competences. Conclusion: In preadolescent children, high competences in locomotor skills and object control skills are associated with high performance on specific executive function tasks. This finding supports the current view that motor competences and cognitive control share some common underlying processes.     

Different durations within the method of best practice affect the parameters of the speed–duration relationship

The aim of the study was to determine whether estimates of the speed–duration relationship are affected using different time-trial (TT) field-based testing protocols, where exhaustive times were located within the generally recommended durations of 2–15?min. Ten triathletes (mean?±?SD age: 31.0?±?5.7?years; height: 1.81?±?0.05?m; body mass: 76.5?±?6.8?kg) performed two randomly assigned field tests to determine critical speed (CS) and the total distance covered above CS (D?). CS and D? were obtained using two different protocols comprising three TT that were interspersed by 60?min passive rest. The TTs were 12, 7, and 3?min in Protocol I and 10, 5, and 2?min in Protocol II. A linear relationship of speed vs. the inverse of time (s?=?D??×?1/t?+?CS) was used to determine parameter estimates. Significant differences were found for CS (p?=?0.026), but not for D? (p?=?0.123). The effect size for CS (d?=?0.305) was considered small, while that for D? was considered moderate (d?=?0.742). CS was significantly correlated between protocols (r?=?0.934; p?D? (r?=?0.053; p?=?0.884). The 95% limits of agreement were ±0.28m?s^?1 and ±73.9?m for CS and D?, respectively. These findings demonstrate that the choice of exhaustive times within commonly accepted durations results in different estimates of CS and D?, and thus protocols cannot be used interchangeably. The use of a consistent protocol is therefore recommended, when investigating or monitoring the speed–duration relationship estimates in well-trained athletes.