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H. Hoteit Ph. Ackerer R. Mos J. Erhel B. Philippe 《International journal for numerical methods in engineering》2004,61(14):2566-2593
In this paper, we introduce an extension of Van Leer's slope limiter for two‐dimensional discontinuous Galerkin (DG) methods on arbitrary unstructured quadrangular or triangular grids. The aim is to construct a non‐oscillatory shock capturing DG method for the approximation of hyperbolic conservative laws without adding excessive numerical dispersion. Unlike some splitting techniques that are limited to linear approximations on rectangular grids, in this work, the solution is approximated by means of piecewise quadratic functions. The main idea of this new reconstructing and limiting technique follows a well‐known approach where local maximum principle regions are defined by enforcing some constraints on the reconstruction of the solution. Numerical comparisons with some existing slope limiters on structured as well as on unstructured meshes show a superior accuracy of our proposed slope limiters. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Critical Shear Stress of Bimodal Sediment in Sand-Gravel Rivers 总被引:1,自引:0,他引:1
A new model for the critical shear stress and the transport of graded sediment is presented. The model is based on the size distribution of the bed surface and can be used to compute sediment transport rates in numerical simulations with an active layer model. This model makes a distinction between unimodal and bimodal sediments. It is assumed that all size fractions of unimodal sediments have the same critical shear stress while there is selective transport for the gravel fractions of bimodal sediments. A recently published laboratory transport data set is used to calibrate our model. 相似文献
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For this study, 194 respondents completed a biographical data sheet, the Templer (1970) Death Anxiety Scale and the Constantinople (1973) Inventory of Psychosocial Development to help assess the relationship among death anxiety, age, and psychosocial maturity. Findings showed that psychosocial maturity was a better predictor of death anxiety than age was. However, both variables were significantly negatively correlated with death anxiety, revealing that as psychosocial maturity and age increase, death anxiety decreases. 相似文献
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This paper is dedicated to the determination of topological S parameters in the transmission line networks. We are especially interested in ideal junctions which consist of short circuit connections. For this type of junctions, it is impossible to deduce the S parameters from the usual impedance or admittance matrices which are not defined in this case. We suggest a method allowing a direct calculation of S. This procedure is described and then carried out for a two wire fork. At last, an experimental application is given for this model. 相似文献
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Although lexical frequencies are familiar measures of stylistic and thematic analysis, only recently have some stylostatisticians been tempted to investigate the relationship between the frequency and topography of repeated lexical items. In the present paper the authors have turned to the study of the four focal types of discursive narratology, using Marguerite Duras'Moderato Cantabile. Their intent is to uncover aspects of narratological performance which further elucidate the communicative strategies in the story. Part 1 summarizes the problematic between frequency and topography. It describes how a topographical index can be computed for any repeated item and how a Global Topography Index (GTI) can summarize the major topographical characteristics of any text sequence. Part 2 presents a four-cell typology of narrational mode: a segmentation of the verbal chain into narrating and narrated speech acts, with each text sequence tagged according to its discursive function: overt sender intervention for story coherence or comment on the focal level of a narrating present; representation of discrete or unlocalized events on the focal level of a mimeticized past. In Part 3 the focal encodings are displayed in numerical and graphic form, first according to the eight surface chapter divisions and then according to twenty-six subsets of approximately equal length. The fluctuations of the topography indices are reviewed, with particular attention being paid to the manifestation of cluster effects. Although sender interventions predominate, the relativized behavior of each focal type contributes to a climactic unraveling of the intrigue in the final chapters. In conclusion, the authors stress the dichotomy between the calm surface of the chapters and the agitated tensions of the twenty-six subsets. 相似文献
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The average and local heat transfer at the base surface of a cylindrical cavity whose opening is perpendicular to an oncoming freestream have been determined experimentally. During the course of the experiments, the cavity depth was varied from zero to 65% of the diameter, while the freestream Reynolds number ranged between about 5000 and 50,000. The average heat transfer coefficient decreased sharply with increasing cavity depth, the reduction being slightly greater than 50% at a depth-diameter ratio of 0.10 and greater than 90% when the depth-diameter ratio was 0.65. For the finite-depth cavities, the local heat transfer coefficient attained its maximum value at the center of the base surface and decreased with increasing radial distance from the center until a minimum was reached, after which there was a moderate increase adjacent to the outer edge of the base. The minimum occurred at the location where the radial outflow along the base separated from the surface, and a toroidal-shaped recirculation zone occupied the corner region at the intersection of the cavity base and side wall. In contrast, for the zero-depth cavity (i.e. a free disk oriented perpendicular to the oncoming flow), the local coefficient attained its minimum at the center of the surface and increased with increasing radial distance from the center. 相似文献
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An account of the postural determinants of perceived reachability is proposed to explain systematic overestimations of the distance at which an object is perceived to be reachable. In this account, these errors are due to a mapping of the limits of prehensile space onto a person's perceived region of maximum stretchability, in the context of a whole-body engagement. In support of this account, 6 experiments on the judged reachability of both static and dynamic objects are reported. We tentatively conclude that the mental imagery of action is grounded and calibrated in reference to multiple skeletal degrees of behavioral freedom. Accordingly, this calibration is a source of systematic error in reachability judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献