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51.
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Olive Chapman 《ZDM》2011,43(6-7):951-963
This article reports on a self-directed, school-based, practice-based professional development (PD) experience aimed at helping elementary school teachers to develop knowledge and expertise in inquiry-based teaching of mathematics. It discusses the characteristics of the self-directed orientation of this PD that supported the teachers’ learning, the nature of the inquiry-based knowledge they constructed, and the impact on their teaching. It highlights the centrality of agency, practical knowledge, and situated learning in this PD approach. The findings suggest that this approach can help mathematics teachers who want to be the architect of their own learning to transform their classrooms in meaningful and desirable ways. 相似文献
54.
Dizaji RM Chapman NR Kirlin RL 《The Journal of the Acoustical Society of America》2002,111(2):800-808
An inversion method based on the concept of back wave propagation (BWP) is described in this paper for estimation of geoacoustic parameters from acoustic field data. A phase-regulation technique is introduced to increase the sensitivity of the method for geoacoustic model parameters having low sensitivity. The case of data consisting of signal plus additive noise is also addressed. It is shown theoretically that the sensitivity can be increased by a factor alpha using the phase regulation procedure, and that the spatial resolution of signal energy that is concentrated by BWP at the known source position is increased when a increases. This result suggests an effective criterion for use in the inversion, based on the spatial distribution of signal energy around the true source location. The basis for the criterion is the spatial variance of the back-propagated pressure field in a window around the known source location. A multistep search process is proposed to avoid using a complicated multidimensional search process. Inversion results from both simulations and experimental data are given. The real data were taken from the Pacific Shelf experiment carried out in shallow water off the West Coast of Vancouver Island in the Northeast Pacific Ocean. 相似文献
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T.A. Chapman 《Topology and its Applications》1981,12(1):19-33
The main result of this paper asserts that any proper fibration over a finite-dimensional ANR with Hilbert cube manifold fibers is a locally trivial bundle. 相似文献
57.
The Aldermaston multi-angle magnetic spectrograph and tandem Van de Graaff accelerator have been used to study the (t, p) reactions leading to the neodymium isotopes 144,146,148,150, 152Nd bombarding energy of 13 MeV. The Q-values were measured for final states with excitation energies up to about 3 MeV. 相似文献
58.
Andrew V. Chapman Michael J. Cook Alan R. Katritzky Michael H. Aabraham Angela F. Danil De Namor Lilane Dumont Jacques Reisse 《Tetrahedron》1978,34(10):1571-1575
The dehydration of various 4,5-dihydro-4- and -5-hydroxy derivatives of pyrazole and isoxazole has been investigated. Heats of dehydration of 4,5-duiydro-4-hydroxy-1,3,5-tripbenylpyrazole and 4,5-dihydro-5-hydroxy-isoxazole are evaluated and used to assess the empirical resonance energy and conjugation energy of pyrazole and isoxazole. The former possesses resonance stabilisation comparable to pyrrole but that of the latter is low. 相似文献
59.
J. Gierak D. Mailly P. Hawkes R. Jede L. Bruchhaus L. Bardotti B. Prével P. Mélinon A. Perez R. Hyndman J.-P. Jamet J. Ferré A. Mougin C. Chappert V. Mathet P. Warin J. Chapman 《Applied Physics A: Materials Science & Processing》2005,80(1):187-194
Controlled and reproducible fabrication of nano-structured materials will be one of the main industrial challenges in the next few years. We have recently proposed exploitation of the nano-structuring potential of a high resolution Focused Ion Beam Tool, to overcome basic limitations of current nano-fabrication techniques. The aim of this article is to present some new routes for material patterning, which benefit from ion-induced local property modifications or damage. In the experiments we describe hereafter an ultra-sharp pencil of 30 keV gallium ions is used to tailor the characteristics of several materials at a scale of a few nanometres. The experimental results are then compared to simulations. First, we simulate the control of collisional defects generated in a thin magnetic layer under FIB irradiation. The results explain the stable magnetic structures we have obtained experimentally. This was achieved with a low surface ion dose (1012 to 1014 ions/cm2). In addition we have explored the promising direction of Bottom-up or self-organization processes using a FIB instrument. We have defined artificial surface defects. These defects created by the impact of an 8-nm FWHM probe were used to pin the diffusion and to organize nanometre-sized gold clusters on a graphite surface. PACS 79.20.Rf; 81.07.-b 相似文献
60.
S.?BlomeierEmail author D.?McGrouther S.?McVitie J. N.?Chapman M. C.?Weber B.?Hillebrands J.?Fassbender 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,45(2):213-218
Structural investigations of the ion irradiated polycrystalline NiFe/FeMn
exchange bias bilayer system were carried out by means of transmission
electron microscopy. Key structural parameters like average grain size,
lattice constant, and texture, as well as their dependence upon ion
irradiation were determined. This information was extracted from a detailed
analysis of a series of bright field images, dark field images, and
diffraction patterns. Furthermore a previously established model was tested
which ascribes changes in the magnetic properties upon irradiation with 5 keV He+ ions
to the creation of point defects within the antiferromagnetic
layer and to the intermixing between the ferromagnetic and antiferromagnetic
layers. The obtained results indirectly support this model by excluding a
change of the aforementioned structural parameters as a possible source of
the observed modifications of the magnetic properties. 相似文献