Optimal time-delayed open/closed-loop control of a damped beam

Vibration suppression of a structurally damped beam via open and closed-loop controls is investigated. In doing so, minimization of a weighted, energy-based performance measure leads to closed-form expressions for optimal open-loop parameters in terms of feedback gains. The control problem is then completed by optimizing these feedback parameters numerically. Methods to determine optimal terminal time of control are also presented. Furthermore, techniques are established to optimize the response and performance of a system experiencing a known feedback time delay. Different types of optimization are proposed and, for each one, the trade-off between performance and computational efficiency is fully discussed.     

Precocious readers: a cognitive or a linguistic advantage?

European Journal of Psychology of Education - We investigated the role of linguistic and cognitive processes in reading precocity from kindergarten to grade 2. A sample of 33 precocious readers was...     

Operant response topographies of rats receiving food or water reinforcers on FR or FI reinforcement schedules

Separate groups of food- and water-deprived rats pressed a lever for food or water, respectively, on continuous reinforcement and various fixed-ratio and fixed-interval reinforcement schedules. Food-reinforced rats on continuous, FR 2-, or FI 10-sec schedules showed consistently longer mean lever contact durations per leverpress than did water-reinforced rats on the same schedules. Mean lever-contact-duration differences between food- and water-reinforced rats were greatly attenuated or disappeared under FR 4-, FR 8-, FI 20-sec, and FI 30-sec schedules of reinforcement. These results are interpreted as supporting earlier hypotheses that there are respondent components of operantly conditioned and autoshaped leverpresses, but that these respondent components weaken with partial reinforcement and the leverpress topography comes under the control of operant contingencies.     

Assumptions underlying educational intervention research: A commentary on Harris and Pressley

This response analyzes Harris and Pressley's position on improving the quality of educational intervention research. It contrasts two different approaches to the interpretation of such research—technology transfer and heuristic interpretations—and their underlying assumptions. Harris and Pressley's positions are generally supported, but within the heuristic rather than the technology transfer perspective.     

Preservice Elementary School Teachers' Understandings of Theory Based Science Education

Journal of Science Teacher Education -     

Current Genetic Discoveries and Education: Strengths, Opportunities, and Limitations

ABSTRACT— This article notes that many key positive developments in education originated in research on the structure and genetics of abilities, providing primary evidence for ability in disadvantaged groups and playing a critical role in demonstrating the existence of developmental learning disorders and effective interventions. It is argued that new work in genetics offers similar hope, but that widely held beliefs about genetic equipotentiality and brain plasticity act as roadblocks to research improving educational outcomes. It is suggested that rebuilding the collaborative links between educationalists and psychometric and genetic research that functioned so effectively in the early development of universal education can again underpin improved educational outcomes.     

Second-wave white teacher identity studies: toward complexity and reflexivity in the racial conscientization of white teachers

Abstract

In this article, we introduce our special issue, ‘Second-Wave White Teacher Identity Studies: Toward Complexity and Reflexivity in the Racial Conscientization of White Teachers.’ We characterize white teacher identity studies as a developing field with important implications for education research and teacher education. Early work in this field focused on documenting, how white teachers denied and evaded the significance of race and white privilege in their work and lives. The articles in this special issue exemplify a second wave of white teacher identity studies which builds on and responds critically to this earlier work. Crucial concerns of this second-wave work include attending to the nuances and complexities of white racial identities, as well as examining the pedagogical, curricular, and institutional contexts within which these identities are taken up.     

The sight and site of North Korea: Citizen cartography’s rhetoric of resolution in the satellite imagery of labor camps

In recent years, satellite mapping of North Korea, especially of its labor camps, has become an important form of evidence of human rights violations, used by transnational advocacy groups to lobby Western governments for change. A phenomenon of “citizen cartography” has emerged where non-expert humanitarian actors use commercially available software like Google Earth to “infiltrate” the borders of North Korea. This essay interrogates the politics of seeing that takes place in creating the site and sight of North Korea by citizen cartographers, and historicizes these processes of seeing in Cold War and post-Cold War visual culture. Specifically, citizen cartography of North Korea engages in rhetorics of resolution, where the cartographer continually searches for a better, clearer view of the ground below, while still constrained by corporate software and logics of state sovereignty that make it difficult to “resolve” the problem of forced labor.     

Are hyoliths Palaeozoic lophophorates?

The phylogenetic position of hyoliths has long been unsettled, with recent discoveries of a tentaculate feeding apparatus (‘lophophore’) and fleshy apical extensions from the shell (‘pedicle’) suggesting a lophophorate affinity. Here, we describe the first soft parts associated with the feeding apparatus of an orthothecid hyolith, Triplicatella opimus from the Chengjiang biota of South China. The tuft-like arrangement of the tentacles of T. opimus differs from that of hyolithids, suggesting they collected food directly from the substrate. A reassessment of the feeding organ in hyolithids indicates that it does not represent a lophophore and our analysis of the apical structures associated with some orthothecids show that these represent crushed portions of the shell and are not comparable to the brachiopod pedicle. The new information suggests that hyoliths are more likely to be basal members of the lophotrochozoans rather than lophophorates closely linked with the Phylum Brachiopoda.     

Considerations of force plate transitions on centre of pressure calculation for maximal velocity sprint running

The aims of this study were to evaluate the accuracy of centre of pressure (COP) data obtained during transition of load across the boundary between two force plates, and secondly to examine the effect of such COP data on joint kinetics during sprint running performances. COP data were collected from two piezoelectric force plates as a trolley wheel was rolled across the boundary between the plates. Position data for the trolley were collected using an opto-electronic motion analysis system for comparison with COP data. Mean COP errors during transition across the plate boundary were 0.003 ± 0.002 m relative to a control point. Kinematic and kinetic data were also collected from eight athletes during sprint running trials to demonstrate the sensitivity of the inverse dynamics analysis to COP error for the ground contact phase of the dynamic movement trials. Kinetic sensitivity to the COP error was assessed during the entire stance phase for the ankle, knee, and hip joints and was less than 5% and 3% for joint moment and power data, respectively. Based on the small COP error during transition across plate boundaries, it is recommended that foot contacts overlapping two force plates may be included in inverse dynamics analyses.