Journal Article•
Mathematical Analysis of Random Noise-Conclusion
About: This article is published in Bell System Technical Journal.The article was published on 1945-01-01 and is currently open access. It has received 807 citations till now.
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01 Jan 1999
TL;DR: It is argued that the most significant characteristic of the level crossings is the probability density function of their interarrival times, and that these characteristics differ a near wall signal from a normal one.
Abstract: Local detection of coherent structures by simple means performed by Eulerian techniques through single or multiple probes, provide useful information for the near wall turbulence control, in an easy and feasible way. Such techniques are undoubtly uncomplete and suffer from the significant smearing produced by the three dimensionality of the random structure advecting past a sensor. Table 1 recapitulates the mostly used Eulerian schemes. Their commun feature is in their detection function. Indeed, almost all of them are based on the level crossings of fluctuating velocity signals, as for example the u-level, quadrant and to some extent VITA and WAG. One of the well known problems encountered in such techniques is the high sensitivity of the number of identified events to the threshold, even though the conditional averages are more or less “universal” in the inner layer, when they are properly normalized. We will first question this dependance and show that the level crossing activity may more or less be estimated by supposing that the signal is Gaussian. Based on this observation, we develop in 3.2 a simple formulation for the “ejection” frequency identified by Eulerian techniques and show the utility of this approach by considering WAG (Table 1). It is further argued that the most significant characteristic of the level crossings is the probability density function of their interarrival times, and that these characteristics differ a near wall signal from a normal one. The grouping methods dealing with the classification of the dynamicaly similar events (Tardu, 1995) are subsequently and briefly reviewed. Finaly some results concerning a simplified model linking the bursting mechanism to the shear stress distribution are presented and discussed.
3 citations
17 May 1999
TL;DR: In this article, the authors describe the radio noise measurement in the VHF band near a road with busy traffic and obtain the time dependent variation of the statistical characteristics of the noise.
Abstract: This paper describes the radio noise measurement in the VHF band near a road with busy traffic. Newly developed APD measuring equipment was used for this measurement together with a spectrum analyzer. The obtained results show the time dependent variation of the statistical characteristics of the noise. The statistical characteristics of the variation would be important for the estimation of EM environments.
3 citations
01 Jan 2017
TL;DR: The advent of performance-based design approach has appeared to be widely accepted by engineering practice but according to this modern design approach, more refined analysis and evaluation of performance objectives needs to be conducted in order to achieve the design goal.
Abstract: The advent of performance-based design approach has appeared to be widely accepted by engineering practice. According to this modern design approach, more refined analysis and evaluation of performance objectives needs to be conducted in order to achieve the design goal. Such a dedicated design process involves many aspects and elements related to hazard assessments, load determination, structural dynamics, structural reliability and structural optimization, all of which are generally reviewed in this chapter.
3 citations
TL;DR: In this paper, a generalized Gaussian Kinematic Formula (GKF) was proposed for multivariate, heterogeneous Gaussian-related fields, which decouples the expected Euler characteristic of excursion sets into Lipschitz Killing Curvatures of the underlying manifold and certain Gaussian Minkowski Functionals.
2 citations
TL;DR: In this paper, the joint distribution of the bearing, elevation and amplitude of a fading radio wave is discussed for several situations realized in practice, including a model of a wave reflected from a completely rough ionosphere, and composed of a number of randomly phased components grouped about some average bearing and elevation.
2 citations