Time-domain simulation of damped impacted plates. II. Numerical model and results

A time-domain model for the flexural vibrations of damped plates was presented in a companion paper [Part I, J. Acoust. Soc. Am. 109, 1422-1432 (2001)]. In this paper (Part II), the damped-plate model is extended to impact excitation, using Hertz's law of contact, and is solved numerically in order to synthesize sounds. The numerical method is based on the use of a finite-difference scheme of second order in time and fourth order in space. As a consequence of the damping terms, the stability and dispersion properties of this scheme are modified, compared to the undamped case. The numerical model is used for the time-domain simulation of vibrations and sounds produced by impact on isotropic and orthotropic plates made of various materials (aluminum, glass, carbon fiber and wood). The efficiency of the method is validated by comparisons with analytical and experimental data. The sounds produced show a high degree of similarity with real sounds and allow a clear recognition of each constitutive material of the plate without ambiguity.     

Molekulargewicht

Ohne Zusammenfassung     

Genre et genre residuel des corps de fonctions values

Let L be a function field of one variable over a valued field (K,|.|), and (|.|_i), 1is, be distinct absolute values over L extending |.| such that the residue fields ¯Lⁱ are function fields of one variable over the residue field ¯K of (K,|.|). We define the defect of the valued function fields (L,|.|_i)/(K,|.|) and prove an inequality between the genus of L/K and that's of ¯Lⁱ/¯K which takes into account the defect, the ramification index of (L,|.|_i)/(K,|.|) and the constant field of Lⁱ/¯K. Our inequality is better than Mathieu's inequality in discretely valued case.     

Maximal wild monodromy in unequal characteristic

Let R be a complete discrete valuation ring of mixed characteristic $(0,p)$ with fraction field K. We study stable models of p-cyclic covers of ${\mathbb{P}}_K^1$. First, we determine the monodromy extension, the monodromy group, its filtration and the Swan conductor for special covers of arbitrarily high genus with potential good reduction. In the case $p=2$ we consider hyperelliptic curves of genus 2.     

Das Atomgewicht des Neodyms

Ohne Zusammenfassung