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51.
This paper reports research on the effects of variations in injection velocity and permeability on the heat transfer and flow
through a highly porous medium between two horizontal parallel plates situated at constant distance with constant suction
by the upper plate. Due to this type of variation in injection velocity and in permeability the flow becomes three dimensional.
The governing equations are solved by adopting complex variable notations to obtain the expressions for the velocity and temperature
field. The skin-friction along the main flow direction and rate of heat transfer are discussed with the help of graphs. 相似文献
52.
53.
This article examines the historical fantasy world created by Joan Aiken in the eleven volumes of her Wolves of Willoughby Chase series. In particular it looks at her subversion of historical reality by the creation of an alternative yet recognisable representation of our own world, using a wide range of events, and the remoulding of aspects of language and geography. It also discusses her reasons for writing in this form and explores the character of Dido Twite as heroine and major raison dtre of the series.This revised version was published online in May 2005 with corrections to the article title. 相似文献
54.
55.
This meta-analysis integrates 296 effect sizes reported in eye-tracking research on expertise differences in the comprehension
of visualizations. Three theories were evaluated: Ericsson and Kintsch’s (Psychol Rev 102:211–245, 1995) theory of long-term working memory, Haider and Frensch’s (J Exp Psychol Learn Mem Cognit 25:172–190, 1999) information-reduction hypothesis, and the holistic model of image perception of Kundel et al. (Radiology 242:396–402, 2007). Eye movement and performance data were cumulated from 819 experts, 187 intermediates, and 893 novices. In support of the
evaluated theories, experts, when compared with non-experts, had shorter fixation durations, more fixations on task-relevant
areas, and fewer fixations on task-redundant areas; experts also had longer saccades and shorter times to first fixate relevant
information, owing to superiority in parafoveal processing and selective attention allocation. Eye movements, reaction time,
and performance accuracy were moderated by characteristics of visualization (dynamics, realism, dimensionality, modality,
and text annotation), task (complexity, time-on-task, and task control), and domain (sports, medicine, transportation, other).
These findings are discussed in terms of their implications for theories of visual expertise in professional domains and their
significance for the design of learning environments. 相似文献
56.
Learners studying mechanical or technical processes via dynamic visualizations often fail to build an accurate mental representation
of the system’s movements. Based on embodied theories of cognition assuming that action, perception, and cognition are closely
intertwined, this paper proposes that the learning effectiveness of dynamic visualizations could be enhanced by grounding
the movements of the presentation in people’s own bodily experiences during learning. We discuss recent research on embodied
cognition and provide specific strategies for how the body can be used to ground movements during the learning process: (1)
making or observing gestures, (2) manipulating and interacting with objects, (3) using body metaphors, and (4) using eye movements
as retrieval cues. Implications for the design of dynamic visualizations as well as directions for future research are presented. 相似文献
57.
Shahron Williams van Rooij 《Educational technology research and development : ETR & D》2011,59(1):139-158
This paper reports the results of a study to identify the extent to which organizations that develop educational/training
products are committed to project management, as measured by their project management implementation maturity, as a methodology
that is separate and distinct from the processes of instructional design. A Web survey was conducted among 103 public and
private sector organizations worldwide that develop educational/training products. Results show no significant difference
by project management maturity level in the roles of instructional designer and project manager, although there is some relationship
between maturity level and how organizations perceive the skills/competencies of project managers versus those of instructional
designers. Further, organizational decision-makers have very specific expectations about the formal education and training
of educational/training product development project leaders. The findings should be of value to institutions of higher education
in evaluating programs that prepare students for careers in instructional design. 相似文献
58.
The exploratory study focused on describing typical routines of preparing for winter outdoor play with preschool children
and their teachers. Naturalistic observations, interviews and photographs resulted in extensive examples of children’s development
in cognitive understanding of winter and winter-related concepts. Observations of teachers and assistants revealed task-oriented
perspectives including detailed strategies and planning. Asynchronous communication and directive language were typical of
teacher/child communication. Photo analyses confirmed physical skills used by preschoolers to accomplish dressing tasks and
extensive curricular changes to indoor environments. 相似文献
59.
The purpose of the study was to investigate the effectiveness of case-based learning instruction over traditionally designed
chemistry instruction on eleventh grade students’ epistemological beliefs and their attitudes toward chemistry as a school
subject. The subjects of this study consisted of 63 eleventh grade students from two intact classes of an urban high school
instructed with same teacher. Each teaching method was randomly assigned to one class. The experimental group received case-based
learning and the control group received traditional instruction. At the experimental group, life cases were presented with
small group format; at the control group, lecturing and discussion was carried out. The results showed that there was a significant
difference between the experimental and control group with respect to their epistemological beliefs and attitudes toward chemistry
as a school subject in favor of case-based learning method group. Thus, case base learning is helpful for development of students’
epistemological beliefs and attitudes toward chemistry. 相似文献
60.
Karel Kreijns Paul A. Kirschner Wim Jochems Hans van Buuren 《Education and Information Technologies》2011,16(4):365-381
Social presence—the degree to which ‘the other’ in a communication appears to be a ‘real’ person—has captured the attention
of those dealing with learning in groups through computer-supported collaborative learning environments. The concept is important
because it affects participation and social interaction, both necessary for effective collaboration and knowledge construction.
This article reports on the construction and validation of a self-reporting (Dutch-language) Social Presence Scale to determine
perceived social presence in distributed learning groups using computer-supported collaborative learning environments. The
result is a one-dimensional scale consisting of five items with an internal consistency of .81. We used a nomological network
of similar constructs for further validation. The findings suggest that the Social Presence Scale has potential to be useful
as a measure for social presence. 相似文献