Near Source Acoustical Particle Velocity Measurements with Ambient Noise

An acoustical measurement very near a structure can be a cheap alternative to other contactless vibration measurement techniques such as laser vibrometry. However, measurements of the acoustical pressure suffer greatly from ambient noise, making these measurements unsuitable for many industrial applications. De Bree and Druyvesteyn suggested that a measurement of the acoustical particle velocity does not have this drawback and provided theory and qualitative measurement results [1]. We present quantitative measurement results of the relative noise contribution in pressure and particle velocity measurements. The ratio of these quantities receives special attention. The model used in previous research is a lumped model, in which some important aspects are neglected. We present results of a numerical model of the vibrating structure and the air. The numerical model and the measurements indicate the same trends but the lumped model does not describe the trends well. Nevertheless, this study also suggests that the sensitivity to background noise is generally considerably greater in pressure measurement than in a particle velocity measurement

Evaluation of new products by New Zealand supermarket retail grocery buyers

Little has been written about the evaluative aspects of new product decisions within the broad reseller market. Reports a study, prior to which no known information existed about New Zealand retail grocery buyers' evaluations of new products, procedures followed or importance attached to various criteria as pertaining acceptance or rejection decisions. Fourteen in-depth interviews with management and buyers, and a subsequent mail questionnaire to 47 potential respondents involving their assessment of the importance attached to criteria in accept or reject decisions were undertaken. Results suggest the application of both “hard” and “soft” core sets of criteria which embody the evaluation of product, supplier and presenter. These criteria are applied to as many as 2,000 products per year, most of which are at the “duplication” end of the new product continuum. Ranks of criteria, and hence assumed central importance, vary depending on the treatment applied, though not a great deal of variation between buyers is suggested. While this may be the case, the company one represents and the use or non-use of a ranging committee seemingly play a determining influence