In this paper a novel Boundary Element (BE) formulation for sensitivity analysis of local active noise control in a three-dimensional field is presented. The formulation is based on the Helmholtz differential equation and it is valid for internal as well as for scattering wave propagation problems. The primary noise is attenuated within an enclosure, called control volume, by adding a control s...

This article introduces a methodology for designing the geometry of diffuse-walled radiant enclosures through nonlinear programming. In this application, the enclosure is represented parametrically using B-spline curves, while the radiosity distribution is solved by infinitesimal-area analysis. The enclosure geometry is repeatedly adjusted with a gradientbased minimization algorithm until a nea...

One of the main problems of interval computations is, given a function f(x 1 problem is feasible for linear functions f, but for generic polynomials, it is known to be computationally intractable. Because of that, traditional interval techniques usually compute the enclosure of y, i.e., an interval that contains y. The closer this enclosure to y, the better. It is desirable to describe cases in...

The voltage on a single-turn loop inside an enclosure characterizes the enclosure shielding effectiveness against a lightning insult. In this paper, the maximum induced voltage on a single-turn loop inside an enclosure from lightning coupling to a metal enclosure wall is expressed in terms of two multiplicative factors: (A) the normalized enclosure wall peak penetration ratio (i.e., ratio of th...

─ This paper deals with an impact of receiving antenna placed in a metal enclosure on an electromagnetic field distribution within the enclosure, and thus on its shielding effectiveness. In an experimental setup, a frequently used tool for measuring the electromagnetic field level at certain points within the enclosure is a dipole antenna connected to a measuring instrument via a coaxial cable....

Hearing loss was the second-most common illness reported to the Mine Safety and Health Administration (MSHA) in 2009. Furthermore, between 2000 and 2010, 30% of all noise-related injury complaints reported to MSHA were for coal preparation plant employees. Previous National Institute for Occupational Safety and Health (NIOSH) studies have shown that vibrating screens are key noise sources to ad...

in the present study, mixed convection laminar flow around an adiabatic body in a lid-driven enclosure filled with nanofluid using variable thermal conductivity and variable viscosity is numerically investigated. the fluid around the body in the enclosure is a water-based nanofluid containing al2o3 nanoparticles. the vertical enclosure’s walls are maintained at constant cold temperature and the...

This paper will review practical techniques and procedures employed to quiet gearboxes and transmission units. The author prefers solving the gear noise problem at the very source to introduce an enclosure as a means to reduce radiated noise, which seems to be easy but its effect on the sound pressure level is small. The gearbox noise problem solution is focused on the improvement of gear desig...

Three enclosures (10 x 10 x 1.5-1.3 m in depth) were set beside Dianch Lake, Kunming, People's Republic of China, for the period from July 28 to August 26, 2002. The enclosures were filled with cyanobacterial (Microcystis aeruginosa) water bloom-containing lake water. Lake sediment that contained macrophytes and water chestnut seeds was spread over the entire bottom of each enclosure. Initially...