3,904 research outputs found

    School effectiveness in East Asia: Concepts, origins and implications

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    Identifies several features in East Asian schools which coincide with commonly recognized characteristics of effective schools in the Western literature: community support, teacher professionalism, attention to quality and high expectations. Attributes this to the East Asian culture and discusses three major dimensions of the East Asian culture: the individual-community dimension, the effort-ability dichotomy and the holistic-analytic tendency in analyses. Traces the origin of such cultural dimensions in the ancient literature and explores the implications of such cultural dimensions in school management. Briefly highlights two major challenges to the adoption of an effective schooling system in East Asia.published_or_final_versio

    Flow transitions and combined free and forced convective heat transfer in rotating curved channels: The case of positive rotation

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    The simultaneous effects of curvature, rotation and heating/cooling in channel flow complicate the flow and heat transfer characteristics beyond those observed in the channels with simple curvature or rotation. The phenomena encountered are examined for steady, hydrodynamically and thermally fully developed flow in square channels. The governing equations are solved numerically by using a finite-volume method. Certain hitherto unknown flow patterns are found. And the results show both the nature of the flow transition and the effect of this transition on the distributions of temperature, friction factor and Nusselt number in a square channel. © 1996 American Institute of Physics.published_or_final_versio

    Visualization of flows in curved channels with a moderate or high rotation speed

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    Flows in channels with streamwise curvature and spanwise rotation are visualized in terms of end-view near the exit of the test sections through injecting smoke into the flows. Two test sections are used, i.e. the rectangular channels with the aspect ratio of 1 and 10, respectively. The work focuses on visualization of Dean and Coriolis vortices under the effects of secondary instabilities and flows in the region with a relatively high rotation speed. The results show that the secondary instabilities cause the Dean and Coriolis vortices oscillating in various forms and the flows at high rotation speeds are controlled by the secondary instabilities rather than the primary instability. In particular, the secondary instabilities lead the flows to be unsteady and turbulent somewhat like the bursting flow in the turbulent boundary layers. © 1997 OPA (Overseas Publishers Association) Amsterdam B.V.published_or_final_versio

    Characterization of piezoelectric ring used for wire bonding transducer application

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    我愛長腿叔叔 - 文字輔導對兒童成長的意義

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    Minimization of current stress on the grid synchronization of doubly-fed induction generators for wind power generation

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    Author name used in this publication: S. L. HoAuthor name used in this publication: K. W. E. ChengVersion of RecordPublishe

    In-plane dielectric properties of epitaxial 0.65Pb(Mg[sub ⅓]Nb[sub ⅔])O₃-0.35 PbTiO₃ thin films in a very wide frequency range

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    Author name used in this publication: Y. WangAuthor name used in this publication: H. L. W. ChanAuthor name used in this publication: C. L. ChoyAuthor name used in this publication: K. C. Cheng2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Performance of large-size superconducting coil in 0.21T MRI system

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    A high-temperature superconductor (HTS) was used on magnetic resonance imaging (MRI) receiver coils to improve image quality because of its intrinsic low electrical resistivity [1], [2]. Typical HTS coils are surface coils made of HTS thin-film wafers. Their applications are severely limited by the field of view (FOV) of the surface coil configuration, and the improvement in image quality by HTS coil is also reduced as the ratio of sample noise to coil noise increases. Therefore, previous HTS coils are usually used to image small in vitro samples, small animals, or peripheral human anatomies [3]-[5]. We used large-size HTS coils (2.5-, 3.5-, and 5.5-in mean diameter) to enhance the FOV and we evaluated their performance through phantom and human MR images. Comparisons were made among HTS surface coils, copper surface coils, and cool copper surface coils in terms of the signal-to-noise ratio (SNR) and sensitivity profile of the images. A theoretical model prediction was also used to compare against the experimental result. We then selected several human body parts, including the wrist, feet, and head, to illustrate the advantage of HTS coil over copper coil when used in human imaging. The results show an SNR gain of 200% for 5.5-in HTS coil versus same size copper coils, while for 2.5- and 3.5-in coils it is 250%. We also address the various factors that affect the performance of large size HTS coils, including the coil-to-sample spacing due to cryogenic probe and the coil-loading effect.published_or_final_versio

    3D simulation of morphological effect on reflectance of Si3N4 sub-wavelength structures for silicon solar cells

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    In this study, we investigate the reflectance property of the cylinder, right circular cone, and square pyramid shapes of silicon nitride (Si3N4) subwavelength structure (SWS) with respect to different designing parameters. In terms of three critical factors, the reflectance for physical characteristics of wavelength dependence, the reflected power density for real power reflection applied on solar cell, and the normalized reflectance (reflected power density/incident power density) for real reflectance applied on solar cell, a full three-dimensional finite element simulation is performed and discussed for the aforementioned three morphologies. The result of this study shows that the pyramid shape of SWS possesses the best reflectance property in the optical region from 400 to 1000 nm which is useful for silicon solar cell applications
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