3,650 research outputs found
Properties of Bipolar Fuzzy Hypergraphs
In this article, we apply the concept of bipolar fuzzy sets to hypergraphs
and investigate some properties of bipolar fuzzy hypergraphs. We introduce the
notion of tempered bipolar fuzzy hypergraphs and present some of their
properties. We also present application examples of bipolar fuzzy hypergraphs
Non-additive interval-valued F-transform
International audienceThis article proposes a new interval-valued fuzzy transform. Its construction is based on a possibilistic interpretation of the partition on which the fuzzy transform is built. The main advantage of this approach is that it provides specific interval valued functions whose interpretation is straightforward. This interpretation relates to a traditional sampling/reconstruction framework where little is known about the sampling and/or reconstructing kernels. Numerous properties of the proposed approach are proved that could be useful for function analysis and comparison. In the experimental section, we illustrate some properties of the proposed transform while highlighting interesting features of the obtained framework
Low-power SNN-based audio source localisation using a Hilbert Transform spike encoding scheme
Sound source localisation is used in many consumer electronics devices, to
help isolate audio from individual speakers and to reject noise. Localization
is frequently accomplished by "beamforming" algorithms, which combine
microphone audio streams to improve received signal power from particular
incident source directions. Beamforming algorithms generally use knowledge of
the frequency components of the audio source, along with the known microphone
array geometry, to analytically phase-shift microphone streams before combining
them. A dense set of band-pass filters is often used to obtain known-frequency
"narrowband" components from wide-band audio streams. These approaches achieve
high accuracy, but state of the art narrowband beamforming algorithms are
computationally demanding, and are therefore difficult to integrate into
low-power IoT devices. We demonstrate a novel method for sound source
localisation in arbitrary microphone arrays, designed for efficient
implementation in ultra-low-power spiking neural networks (SNNs). We use a
novel short-time Hilbert transform (STHT) to remove the need for demanding
band-pass filtering of audio, and introduce a new accompanying method for audio
encoding with spiking events. Our beamforming and localisation approach
achieves state-of-the-art accuracy for SNN methods, and comparable with
traditional non-SNN super-resolution approaches. We deploy our method to
low-power SNN audio inference hardware, and achieve much lower power
consumption compared with super-resolution methods. We demonstrate that signal
processing approaches can be co-designed with spiking neural network
implementations to achieve high levels of power efficiency. Our new
Hilbert-transform-based method for beamforming promises to also improve the
efficiency of traditional DSP-based signal processing
An algorithm design environment for signal processing
Also issued as Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1989.Includes bibliographical references (p. 253-256).Supported in part by the Defense Advanced Research Projects Agency and monitored by the Office of Naval Research. N00014-89-J-1489 Supported in part by the National Science Foundation. MIP 87-14969 Supported in part by Sanders Associates, Incorporated.Michele Mae Covell
Bayesian modelling for determining material properties
Sound wave propagation in materials has been used extensively for nondestructive testing of materials, studying the internal structure of Earth or for oil/gas/mineral exploration. The propagation characteristics have been exploited and studied using signal processing tools for analyzing the material properties or for examining the sub-surface features. The signal processing tools can be innovated in accordance with the characteristics of the sound wave propagation in the media for improvement of the signal to noise ratio. A synthetic model of one dimensional chain of spherical particles is used to generate space time responses when impulse moves along the chain, it gives information about the longitudinal wave propagation (P-wave). The space time responses obtained from the synthetic model are used by the Bayesian inference technique to obtain the properties of the media (particle size/mass distribution of the chain). Finally, the importance of Bayesian inference technique as a signal processing tool is discussed upon
AN IMPROVED METHOD FOR THE IDENTIFICATION AND INVERSION OF MULTI-MODE RAYLEIGH SURFACE WAVE DISPERSION COLLECTED FROM NON-UNIFORM ARRAYS UTILIZING A MOVING SOURCE APPROACH
An improved method using a moving source approach is utilized in the analysis of Rayleigh surface waves for the accurate identification of higher mode propagation used in inversion. Two non invasive surface wave methods, Multi- station Analysis of Surface Waves (MASW) and Refraction Microtremor (ReMi) were used for the construction of composite dispersion curves representing the relationship of Rayleigh phase velocity (VR) with frequency. Multiple tests were executed with source offsets increasing with each successive test in order to account for near field effects and higher mode attenuation levels. The resulting dispersions were combined to form a composite dispersion which effectively maps all participating modes of propagation. The inversion was executed using a genetic algorithm (GA) which takes advantage of the Rayleigh forward problem. The results show good ability to identify intermediate high and low velocity layers and agree well with downhole results
Study of star-forming galaxies in SDSS up to redshift 0.4 II. Evolution from the fundamental parameters: mass, metallicity & SFR
To understand the formation and evolution of galaxies, it is important to
have a full comprehension of the role played by the metallicity, star formation
rate (SFR), morphology, and color. The interplay of these parameters at
different redshifts will substantially affect the evolution of galaxies and, as
a consequence, the evolution of them will provide important clues and
constraints on the galaxy evolution models. In this work we focus on the
evolution of the SFR, metallicity of the gas, and morphology of galaxies at low
redshift in search of signs of evolution. We use the S2N2 diagnostic diagram as
a tool to classify star--forming, composite, and AGN galaxies. We analyzed the
evolution of the three principal BPT diagrams, estimating the SFR and specific
SFR (SSFR) for our samples of galaxies, studying the luminosity and
mass-metallicity relations, and analyzing the morphology of our sample of
galaxies through the g-r color, concentration index, and SSFR. We found that
the S2N2 is a reliable diagram to classify star--forming, composite, and AGNs
galaxies. We demonstrate that the three principal BPT diagrams show an
evolution toward higher values of [OIII]5007/Hb due to a metallicity decrement.
We found an evolution in the mass-metallicity relation of ~ 0.2 dex for the
redshift range 0.3 < z < 0.4 compared to our local one. From the analysis of
the evolution of the SFR and SSFR as a function of the stellar mass and
metallicity, we discovered a group of galaxies with higher SFR and SSFR at all
redshift samples, whose morphology is consistent with those of late-type
galaxies. Finally, the comparison of our local (0.04<z<0.1) with our higher
redshift sample (0.3<z<0.4), show that the metallicity, the SFR and morphology,
evolve toward lower values of metallicity, higher SFRs, and late--type
morphologies for the redshift range 0.3<z<0.4Comment: 16 pages, 15 figures. Accepted for publication in A&
Workshop on Fuzzy Control Systems and Space Station Applications
The Workshop on Fuzzy Control Systems and Space Station Applications was held on 14-15 Nov. 1990. The workshop was co-sponsored by McDonnell Douglas Space Systems Company and NASA Ames Research Center. Proceedings of the workshop are presented
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