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Navigating the Turbulent Waters of School Reform Guided by Complexity Theory
The goal of this research study has been to develop, implement, and evaluate a school reform design experiment at a continuation high school with low-income, low-performing underrepresented minority students. The complexity sciences served as a theoretical framework for this design experiment. Treating an innovative college preparatory program as a nested complex adaptive system within a larger complex adaptive system, the school, we used features of complex adaptive systems (equilibrium, emergence, self-organization, and feedback loops) as a framework to design a strategy for school reform. The goal was to create an environment for change by pulling the school far from equilibrium using a strategy we call āpurposeful perturbationsā to disrupt the stable state of the school in a purposeful way. Over the four years of the study, several tipping points were reached, and we developed agent-based simulation models that capture important dynamic properties of the reform at these points. The study draws upon complexity theory in multiple ways that have supported improved education for low-achieving students
AC-Tolerant Multifilament Coated Conductors
We report the magnetization losses in an experimental multifilament coated
conductor. A 4 mm wide and 10 cm long YBCO coated conductor was subdivided into
eight 0.5 mm wide filaments by laser ablation and subjected to post-ablation
treatment. As the result, the hysteresis loss was reduced, as expected, in
proportion to the width of the filaments. However, the coupling loss was
reduced dramatically, and became practically negligible, in the range of a
sweep rate up to 20 T/s. This represents a drastic improvement on previous
multifilament conductors in which often the coupling losses became equal to the
hysteresis loss at a sweep rate as low as 3-4 T/s. These results demonstrate
that there is an effective and practical way to suppress coupling losses in
coated multifilament conductors.Comment: This paper is based on a talk given at 2006 Applied Superconductivity
Conference in Seattle, WA (August 27-September 1, 2006). To be published in
IEEE Trans. Appl. Superconductivit
The effects of superconductor-stabilizer interfacial resistance on quench of current-carrying coated conductor
We present the results of numerical analysis of a model of normal zone
propagation in coated conductors. The main emphasis is on the effects of
increased contact resistance between the superconducting film and the
stabilizer on the speed of normal zone propagation, the maximum temperature
rise inside the normal zone, and the stability margins. We show that with
increasing contact resistance the speed of normal zone propagation increases,
the maximum temperature inside the normal zone decreases, and stability margins
shrink. This may have an overall beneficial effect on quench protection quality
of coated conductors. We also briefly discuss the propagation of solitons and
development of the temperature modulation along the wire.Comment: To be published in Superconductor Science and Technology. This
preprint contains one animated figure (Fig. 6(a)). when asked whether you
want to play the content, click "Play". Acrobat Reader (Windows and Mac, but
not Linux) will play embedded flash movies. In the printed copy Fig. 6(b)
will show the temperature profile at gamma t=15
Uniqueness of the solution to inverse scattering problem with scattering data at a fixed direction of the incident wave
Let be real-valued compactly supported sufficiently smooth function.
It is proved that the scattering data , determine uniquely. Here is a fixed
direction of the incident plane wave
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