the ever increasing rate of power consumption has led to an increase in public exposure to extremely low frequency magnetic fields (elf-mfs) and brought severe concerns about their health effects. considering previous studies and the facts about potential health effects of these fields, the present study aimed to evaluate the elf-mf flux densities from power distribution lines near hospitals i...

In this paper, a wave propagation model is developed to investigate the wave propagation in fluid-filled steel pipe. Based on the Kennard shell equations the investigation is achieved under the conditions of coupling between the shell elastic acoustic field and the interior fluid acoustic field. Tests are conducted on fluid-filled pipeline blockage detection. An active acoustic source is used t...

The Wigner distribution (WD) is perhaps the most prominent quadratic time–frequency signal representation. In this paper, which has mainly tutorial character but also contains some new results, we describe extensions of the WD concept to multidimensional vector signals, nonstationary random processes, linear time-varying systems (deterministic and random), linear signal spaces, and frames. We d...

This work deals with the analysis of chirp signals by means of time-frequency representation. We propose a chirp adapted time-frequency representation (CA) in which the interferences are significantly reduced. This method is applied to the analysis of acoustic echoes of a sphere target. Comparison of the results to other types of time-frequency distribution of the Cohen’s class shows that the i...

We introduce a time-frequency representation of linear signal spaces which we call the Wigner distribution (WO) ofa linear signal space. Similar to the WD of a signal, the WD of a linear signal space describes the space’s energy distribution over the time-frequency plane. The WD of a signal space can be defined both in a deterministic and in a stochastic framework, and it can be expressed in a ...

A magnitude-frequency analysis of rockslide-debris avalanche deposits was performed. Hummocks are conical mounds formed in debris avalanche deposits from the catastrophic sector collapse of a mountain (often volcanic) that represent relatively cohesive fragments of the mountain edifice. Examination of 17 debris avalanche deposits in Japan and the Philippines showed that, in general, the larger ...

Scale is a physical attribute of a signal which occurs in many natural settings. Time-frequency distributions (TFDs) belonging to Cohen’s class are invariant to time and frequency shifts, but are not necessarily covariant to the time scalings of the signal. Conditions on the time-frequency kernel for yielding a scale covariant distribution have been previously derived (Cohen, 1995) . In this pa...