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The acoustical performance of a vehicle dash panel system is rated by the noise reduction, which is calculated from the sound transmission and absorption characteristics. A typical dash insulator consists of a steel panel (vehicle body panel), a porous decoupler and heavy layer in the form of sandwich construction. The use of dash panel is to block engine noise from entering into the interior cabin. In the present study the transmission loss of dash panel has been evaluated in reverberation chambers and the sound absorption of dash panel has been determined in impedance tube. This paper deals with improving over all sound transmission loss and shifting of the double wall resonance well below the engine firing frequencies by changing the decoupler materials such as felt and foams of different density and thickness and heavy layer mass per unit area.

Three dimensional finite element analysis of mufflers has been carried out using ANSYS general purpose program. Analysis of simple expansion chamber muffler, extended tube muffler, tapered chamber muffler, offset chamber muffler and flow reversing chamber muffler has been carried out to predict the transmission loss. This three dimensional FEA technique has proved to be successful for the analysis of geometrically complicated mufflers where one dimensional theories can not be used. Parametric analysis of a simple expansion chamber muffler has been carried out to study the effect of expansion ratio, expansion chamber length, number of partitions within a chamber and unequal partitions. Analysis of acoustic cavity of a simple expansion chamber muffler has also been carried out to predict the natural frequencies and acoustic mode shapes.

The characteristics, functionality, limitations, and applications of mid-level driving simulators are reviewed and discussed. For this paper a mid-level simulator is defined as one which has a large roadway scene display typically comprising animated computer graphics, it may have a motion system or be fixed base, it should have a dedicated cab with a steering feel system and interactive controls and displays, it has a parametrically configurable vehicle dynamics model, data acquisition is provided for, and the simulator is intended to be used for driver behavior research and vehicle or highway research and development studies. Possible simulator sickness issues are discussed, and categories of mid-level driving simulator applications are noted. Approximately 20 different contemporary driving simulators are included in the survey.