The article presents a brief exposition of alternative ways of creating virtual objects and the status of their existence inspired by the relevant views of Plato, Aristotle, Franz Brentano and Karl Popper as well as various conceptions of representation. I argue that the present state of research on the problem of “computer” virtuality shows that it is necessary to explore first the ontological issues of virtual objects. Only these issues will solve the mystery of the creation and existence of virtual objects. The consideration of these issues are suppressed by the fact that contemporary philosophy has removed both metaphysics and, with-it, ontology. That is why, and for reasons for reasons of substantive accuracy, I show how traditional ontological and ontologically inspiring approaches are—when modified— promising candidates for exploring the nature of virtual objects, first of all, problems of their existence and creation.
In this paper, we estimate the upper limit of the transmission data rate in airborne ultrasonic communications, under condition of the optimal power allocation. The presented method is based on frequency response of a channel in case of single-path LOS propagation under different climatic conditions and AWGN background noise model, and it can be easily extended to the case of frequency-dependent noise. The obtained results go beyond the discrete distances for which experimental SNR values were available, and are more accurate than the previous calculations in the literature, due to the inclusion of the channel frequency response and its changes over the distance. The impact of air temperature, relative humidity and the atmospheric pressure on the channel capacity is also investigated. The presented results can serve as a reference during the design of airborne ultrasonic communication systems operating in the far-field region.