𝔖 Bobbio Scriptorium
✦   LIBER   ✦

EXACT AND APPROXIMATE DIRECTIVITY PATTERNS OF THE SOUND RADIATED FROM A CYLINDRICAL DUCT

✍ Scribed by S.T. HOCTER

Publisher
Elsevier Science
Year
1999
Tongue
English
Weight
156 KB
Volume
227
Category
Article
ISSN
0022-460X

No coin nor oath required. For personal study only.

✦ Synopsis

The exact solution for radiation from a cylindrical pipe obtained by using the Wiener}Hopf method has been available for over 50 years. Approximate solutions can be used to simplify the problem, and their accuracy compared with the exact solution. Firstly, the exact solution can be simpli"ed by using the method of the steepest descent to cast the problem in the form of Weinstein's ;-approximation. A simpler technique involves the use of the Kirchho! approximation. This vastly simpli"es the problem by considering the radiation emanating from a circular aperture in a thin screen. The various formulae are then compared in a parameter space related to the physical structure of a propagating model. If one considers the behaviour of the approximations solely as one of the governing parameters is altered (i.e., as k a is increased), the physical behaviour of the propagating mode would not linearly change. In considering the parameters in terms of mode angles, one can observe the accuracy of the approximations for various parameters while linearly changing the ray structure.

📜 SIMILAR VOLUMES

SOUND PROPAGATION IN A MOVING FLUID CONF
SOUND PROPAGATION IN A MOVING FLUID CONFINED BY CYLINDRICAL WALLS—A COMPARISON BETWEEN AN EXACT ANALYSIS AND THE LOCAL-PLANE-WAVE APPROXIMATION
✍ M. WILLATZEN 📂 Article 📅 2001 🏛 Elsevier Science 🌐 English ⚖ 301 KB

A discussion of sound propagation in a moving #uid con"ned by cylindrical walls is presented. Based on the continuity equation and the Euler equation, a single &&exact'' ordinary di!erential equation in the acoustic pressure is derived for the case where the medium #ow v (r) depends on the radial co

Determination of the Rotational Diffusio
Determination of the Rotational Diffusion Tensor of Macromolecules in Solution from NMR Relaxation Data with a Combination of Exact and Approximate Methods—Application to the Determination of Interdomain Orientation in Multidomain Proteins
✍ Ranajeet Ghose; David Fushman; David Cowburn 📂 Article 📅 2001 🏛 Elsevier Science 🌐 English ⚖ 335 KB

In this paper we present a method for determining the rotational diffusion tensor from NMR relaxation data using a combination of approximate and exact methods. The approximate method, which is computationally less intensive, computes values of the principal components of the diffusion tensor and es