Speed Of Arrival Research Articles

Diffusion Characteristics of VOCs Indoors

AbstractDiffusion characteristics of volatile organic compounds (VOCs) were investigated indoors using tin oxide gas sensors. The chemicals cause various kinds of symptoms in humans, for example, the sick house syndrome. In this study, eight sensors were installed in a vertical direction and on a plane surface. These sensors were of the same type. The VOC is placed in a generation source, and the sensor output increases as the chemical diffuses. The sensor output becomes higher as the concentration increases. The following chemicals were tried as air pollutants: formaldehyde, toluene, and xylene. The sensor output changes in short, quick steps by slight fluctuations of the wind velocity. Therefore, the differential characteristic of the sensor output was adopted and the noise component was removed as far as possible. A threshold time tth to the characteristic was set up. It is assumed that the examining chemical reaches the installed sensor point in a time greater than this time. The new speed of arrival is proposed using the threshold time. The speed s [cm/min] is indicated using the distance d and the reaching time tth, namely, s = d/tth. Here, d means the distance between the sensor position and the polluting source. As a result, the speed for the sensor that is installed near the ceiling (at a height of 260 cm from the floor) is the highest. And, it became obvious that s was larger for the chemical with a smaller molecule. The speed of formaldehyde for the sensor installed near the ceiling was 700 cm/min and that for the sensor installed at the height of 100 cm from the floor was 370 cm/min. There is almost a two times difference in the speed. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Strategic technology investment under uncertainty

In this paper the technology investment decision of a firm is analyzed, while competition on the output market is explicitly taken into account. Technology choice is irreversible and the firms face a stochastic innovation process with uncertainty about the speed of arrival of new technologies. The innovation process is exogenous to the firms. For reasons of market saturation and the fact that more modern technologies are invented as time passes, the demand for a given technology decreases over time. This implies that also the sunk cost investment of each technology decreases over time.

Refraction of infrasound by upper-atmospheric winds

We used realistic models of upper-atmospheric winds in a three-dimensional acoustic ray-tracing program to calculate how much wind refraction alters acoustic transit speed and azimuth of arrival for long-distance paths. Transit speed varied by 20% or more, and bearing deviations of up to ten degrees were found, depending on the season and on the direction the waves travel. On the average, the predicted seasonal trends corresponded to osbervations, but the calculated standard deviations exceed the mean seasonal values, making simple corrections useless in individual cases. Furthermore, it is doubtful that variations of horizontally uniform winds alone can account for the large observed variability in refractive effects, specifically the large differences in bearing error at adjacent observatories. We show that realistic horizontal gradients of either temperature or wind could cause as much azimuthal refraction as our height-dependent wind models.

Test of a Relativity Postulate

CLERK MAXWELL'S original suggestion, revived in NATURE for April 12, p. 566, was in danger of being lost sight of, although it has been renewed independently from time to time; see, for example, Phil. Trans., 1893, p. 784. The prevailing relativity postulate that motion through the ether is undetectable, or in another form that no motion of an observer can affect his determination of the velocity of light in free space, has not yet been actually and directly verified. Common sense seems to assert that motion of source can have no influence on waves after they have left it, while motion of receiver should subjectively affect their speed of arrival; but this would be contrary to the relativity postulate.