共查询到20条相似文献,搜索用时 62 毫秒
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所谓调控艺术,就是指对数学课堂教学中的主要变量的适当、合理的调节控制。即通过整体的控制、信息的筛滤、情感的合度以及节奏的调节,使课堂教学呈现出张弛有度、和谐自然、意趣盎然的生动格局。 (一)整体的控制整体控制,是指对课堂教学的整体上的构思与设计.整体控制是否全面、合理,虽然难以划定绝对的界限与尺寸,但是仍有标准可循,我们可用以下三项指标进行评估: 1.结构合理度这是指课堂结构形式对教学内容的适应程度,以及新旧知识要素存在的比例是否恰当. 不同课堂结构模式具有自身独特的功能: ①传递接受式:复习旧课——讲授新课 相似文献
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Tongke 《高等学校计算数学学报(英文版)》2010,3(4)
<正>This paper presents alternating direction finite volume element methods for three-dimensional parabolic partial differential equations and gives four computational schemes,one is analogous to Douglas finite difference scheme with second-order splitting error,the other two schemes have third-order splitting error,and the last one is an extended LOD scheme.The L~2 norm and H~1 semi-norm error estimates are obtained for the first scheme and second one,respectively.Finally,two numerical examples are provided to illustrate the efficiency and accuracy of the methods. 相似文献
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Elena 《高等学校计算数学学报(英文版)》2010,3(4)
<正>In this work we consider the problem of shape reconstruction from an unorganized data set which has many important applications in medical imaging,scientific computing,reverse engineering and geometric modelling.The reconstructed surface is obtained by continuously deforming an initial surface following the Partial Differential Equation(PDE)-based diffusion model derived by a minimal volume-like variational formulation.The evolution is driven both by the distance from the data set and by the curvature analytically computed by it.The distance function is computed by implicit local interpolants defined in terms of radial basis functions.Space discretization of the PDE model is obtained by finite co-volume schemes and semi-implicit approach is used in time/scale.The use of a level set method for the numerical computation of the surface reconstruction allows us to handle complex geometry and even changing topology, without the need of user-interaction.Numerical examples demonstrate the ability of the proposed method to produce high quality reconstructions.Moreover,we show the effectiveness of the new approach to solve hole filling problems and Boolean operations between different data sets. 相似文献
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Generalizing wavelets by adding desired redundancy and flexibility,framelets(i.e.,wavelet frames)are of interest and importance in many applications such as image processing and numerical algorithms.Several key properties of framelets are high vanishing moments for sparse multiscale representation,fast framelet transforms for numerical efficiency,and redundancy for robustness.However,it is a challenging problem to study and construct multivariate nonseparable framelets,mainly due to their intrinsic connections to factorization and syzygy modules of multivariate polynomial matrices.Moreover,all the known multivariate tight framelets derived from spline refinable scalar functions have only one vanishing moment,and framelets derived from refinable vector functions are barely studied yet in the literature.In this paper,we circumvent the above difficulties through the approach of quasi-tight framelets,which behave almost identically to tight framelets.Employing the popular oblique extension principle(OEP),from an arbitrary compactly supported M-refinable vector functionφwith multiplicity greater than one,we prove that we can always derive fromφa compactly supported multivariate quasi-tight framelet such that:(i)all the framelet generators have the highest possible order of vanishing moments;(ii)its associated fast framelet transform has the highest balancing order and is compact.For a refinable scalar functionφ(i.e.,its multiplicity is one),the above item(ii)often cannot be achieved intrinsically but we show that we can always construct a compactly supported OEP-based multivariate quasi-tight framelet derived fromφsatisfying item(i).We point out that constructing OEP-based quasi-tight framelets is closely related to the generalized spectral factorization of Hermitian trigonometric polynomial matrices.Our proof is critically built on a newly developed result on the normal form of a matrix-valued filter,which is of interest and importance in itself for greatly facilitating the study of refinable vector functions and multiwavelets/multiframelets.This paper provides a comprehensive investigation on OEP-based multivariate quasi-tight multiframelets and their associated framelet transforms with high balancing orders.This deepens our theoretical understanding of multivariate quasi-tight multiframelets and their associated fast multiframelet transforms. 相似文献
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Ahmad AL-SALMAN 《Frontiers of Mathematics in China》2021,16(1):13-28
We introduce a class of singular integral operators on product domains along twisted surfaces.We prove that the operators are bounded on Lp provided that the kernels satisfy weak conditions. 相似文献
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The various kinetic processes are classified and the place of relaxation effects among them is established. The theoretical basis of mechanical relaxation phenomena in polymers is outlined. The characteristics of relaxation processes associated with molecular mobility are examined with reference to various classes of polymers, in particular, amorphous and crystalline polymers, copolymers, and mechanical mixtures. The characteristics of relaxation processes associated with rearrangement of the supermolecular structures in amorphous and crystalline polymers are considered.This article is a review of mechanical relaxation effects in polymers with particular attention to research conducted in the Problem Laboratory of Polymer Physics of the Moscow Lenin State Pedagogical Institute.Problem Laboratory of Polymer Physics, Lenin Moscow State Pedagogical Institute. Translated from Mekhanika Polimerov, Vol. 5, No. 1, pp. 30–53, January–February, 1969. 相似文献
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In this paper,we investigate the relaxation phenomenon for quasilinear hyper- bolic conservation laws,and obtain global smooth solutions and the life span of classical solutions to its Canchy problem.These results shows that the relaxation admits the effects of dissipation. 相似文献
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The spectra of the dielectrical constant and dielectrical loss in three nanostructured α-Fin23 samples at different annealed temperatures are measured by using ac LRC method. The relaxation times of polarization and
the conductance are calculated by means of the Debye mechanism and the interface effects in two kinds of polarization processes
with two different relaxation times are proposed.
Project supported by the Natural Science Foundation of zhejiang Province and the Chinese Postdoctoral Foundation. 相似文献
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The various types of molecular-kinetic effects are examined and the place of relaxation processes among them is determined. The transitions in noncrystalline and crystalline polymers are classified in accordance with physical principles. The experimental results of a study of molecular mobility on a broad temperature interval are analyzed for bulk polymers with different effective chain stiffnesses. The importance of taking into account the various relaxation processes that develop in polymers used in different branches of technology is noted. 相似文献
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本文研究合灰气体激波沿平直壁面传播过程中在壁面附近形成的层流边界层流动.我们依照双连续介质双向耦合模型处理含灰气体激波的波后流动及其诱导的边界层问题,控制方程采用有限差分方法数值求解,给出了激波下游两相流场特性并考虑了含灰气体激波的松弛结构对边界层流动的影响. 相似文献
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Diffusion theory of slow responses 总被引:1,自引:0,他引:1
When an action is applied to a macroscopic substance, there is a particular sort of slow response besides the well-known fast
response. Using diffusion theory, the characteristics of slow response in dielectric, elastic, piezoelectric, and pyroelectric
relaxation may be explained. A time domain spectroscopy method suitable for slow and fast responses in linear and nonlinear
effects is given. Every relaxation mechanism contributes a peak in differential spectroscopy, and its position, height, and
line shape show the dynamical properties of the mechanism. The method of frequency domain spectroscopy is suitable only for
linear fast response. Time domain spectroscopy is another nonequivalent powerful method. The theory is confirmed by a lot
of experimental data.
Project supported by the National Natural Science Foundation of China and the Science Foundation of Zhongshan University. 相似文献
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We discuss qualitative aspects of a continuum theory for thin films rigorously derived in [B. Schmidt, On the passage from atomic to continuum theory for thin films, preprint 82/2005, Max-Planck Institut für Mathematik in den Naturwissenschaften, Leipzig]. The stored energy density is examined for convexity properties and limiting behavior under large and small strains. A study of the dependence of the theory on relaxation parameters leads to the result that the scale of convergence used in [B. Schmidt, On the passage from atomic to continuum theory for thin films, preprint 82/2005, Max-Planck Institut für Mathematik in den Naturwissenschaften, Leipzig] is the only scale for which a limiting theory that also accounts for atomic relaxation effects is non-trivial. 相似文献
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J. D. Hoffman M. P. Scofield H. D. Thompson 《Journal of Optimization Theory and Applications》1972,10(3):133-159
An optimization analysis employing the calculus of variations and a numerical relaxation scheme for applying the results are presented for the design of axisymmetric, maximumthrust nozzle contours including boundary-layer effects. The method is illustrated by comparison with a known solution without boundary-layer effects. A parametric study of boundary-layer effects for a range of parameters typical of scramjet thrust nozzles is presented.This work was sponsored by the Air Force Aero-Propulsion Laboratory, Wright-Patterson Air Force Base, Ohio, under Contract No. F33615-67-C-1068. 相似文献
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D. Tripathi 《Applied mathematics and computation》2010,215(10):3645-452
The paper presents the transportation of viscoelastic fluid with fractional Maxwell model by peristalsis through a channel under long wavelength and low Reynolds number approximations. The propagation of wall of channel is taken as sinusoidal wave propagation (contraction and relaxation). Homotopy perturbation method (HPM) and Adomian decomposition method (ADM) are used to obtain the analytical approximate solutions of the problem. The expressions of axial velocity, volume flow rate and pressure gradient are obtained. The effects of fractional parameters (α), relaxation time (λ1) and amplitude (?) on the pressure difference and friction force across one wavelength are calculated numerically for different particular cases and depicted through graphs. 相似文献