Vortex Noise from Rotating Cylindrical Rods

A series of round rods of the some diameter were rotated individually about the mid-point of each rod. Vortices are shed from the rods when in motion, giving rise to the emission of sound. With the rotating system placed in the open air, the distribution of sound in space, the acoustical power output, and the spectral distribution have been studied. The frequency of emission of vortices from any point on the rod is given by the formula von Karman. From the spectrum estimates are made of the distribution of acoustical power along the rod, the amount of air concerned in sound production, the "equivalent size" of the vortices, and the acoustical energy content for each vortex

Navigating the gap between action and a serving information system

Creating, or adapting, information systems to support people undertaking purposeful action in organizational settings involves moving from: exploring the problem situation and thinking about what action to take, to thinking about how to support that action. In business settings this support will inevitably entail technology-based information systems. Most information system design approaches neglect the importance of the initial exploration and sense making phase and move directly to specifying the business process to be operationalised through the application of some software. The ideas described here have been developed with the intention of supporting a group of people navigating an inquiry through the shift in focus from: thinking about action, to thinking about support in a manner that promotes Client-led information system design. The ideas have been applied in practice through an Action Research field study in a UK banking organization and here we describe our navigational approach to IS design

Float-polishing process and analysis of float-polished quartz

A fluid-mechanical model is developed for the float-polishing process. In this model laminar flow between the sample and the lap results in pressure gradients at the grooves that support the sample on a fluid layer. The laminar fluid motion also produces supersmooth, damage-free surfaces. Quartz substrates for applications in high-stress environments were float polished, and their surfaces were analyzed by optical scatterometry, photoacoustic spectroscopy, and atomic force microscopy. The removal of 100 µm of material by a lapping-polishing process, with final float polishing, left low levels of subsurface damage, with a surface roughness of approximately 0.2-nm rms

Noise from Two-Blade Propellers

The two-blade propeller, one of the most powerful sources of sound known, has been studied with the view of obtaining fundamental information concerning the noise emission. In order to eliminate engine noise, the propeller was mounted on an electric motor. A microphone was used to pick up the sound whose characteristics were studied electrically. The distribution of noise throughout the frequency range, as well as the spatial distribution about the propeller, was studied. The results are given in the form of polar diagrams. An appendix of common acoustical terms is included