In this paper, we demonstrate how to reduce the noise level of expanded air from pneumatic tools. Instead a muffler, propose collecting system, where expands through tube and expansion collector. We have elaborated mathematical model which illustrates dynamics flow, as well acoustic pressure at end tube. The computational results were compared with experimental data check sound pressure. Moreov...

An analytical model based on modal series expansion method for calculating transmission loss (TL) of compressor’s mufflers has been present in this paper. The approximately averaged pressure response value, obtained by calculating the weighted average pressure response value in the vicinity of the point source, is applied to derive the pressure response functions and four-pole parameters. There...

It is generally believed that readers decompose a complex word into its constituent morphemes only when those morphemes participate productively in word formation. Here we recorded event-related potentials (ERPs) to words (e.g. muffler, receive), non-words containing no morphemes (e.g. flermuf), and non-words containing a prefix and a non-productive bound stem (e.g. in-ceive). Prior work has sh...

An epidemiological survey was conducted in Houston, Texas on five trace metals in policemen, parking garage attendants, women living near freeways and three control groups of subjects. The controls were matched with the exposed groups for covariate information such as age, sex, smoking habits, ethnic background, socioeconomic status, hair color, and education. Each subject was sampled four time...

Motorcycles generate different sound patterns under dissimilar working conditions. The generated sound pattern gives a clue of the fault. Mainly the parts of the engine that lead to change in sound are cylinder kit, crank, timing chain, and valve. The parts of the exhaust system that change sound under fault are muffler and silencer. In this study, we analyze the sound signals produced by motor...

The filtered fluid dynamic equations are discretized in space by a high-order spectral difference(SD) method coupled with large eddy simulation (LES) approach. The subgrid-scale stress tensor is modelled by the wall-adapting local eddy-viscosity model (WALE). We solve the unsteady equations by advancing in time using a second-order backward difference formula (BDF2). The nonlinear algebraic sys...

The study of sound attenuation in an elliptical chamber involves the solution of the Helmholtz equation in elliptic coordinate systems. The Eigen solutions for such problems involve the Mathieu and the modified Mathieu functions. The computation of such functions poses considerable challenge. An alternative method to solve such problems had been proposed in this paper. The elliptical cross-sect...