scholarly journals Contribution of bone-reverberated waves to sound localization of dolphins: A numerical model

Acta Acustica ◽  
2020 ◽  
Vol 5 ◽  
pp. 3
Author(s):  
Aida Hejazi Nooghabi ◽  
Quentin Grimal ◽  
Anthony Herrel ◽  
Michael Reinwald ◽  
Lapo Boschi
Keyword(s):  
Wave Propagation ◽  
Numerical Model ◽  
Sound Localization ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Dimensional Structure ◽  
Bone Modeling ◽  
Sound Sources ◽  
Localization Accuracy ◽  
Future Work

We implement a new algorithm to model acoustic wave propagation through and around a dolphin skull, using the k-Wave software package [1]. The equation of motion is integrated numerically in a complex three-dimensional structure via a pseudospectral scheme which, importantly, accounts for lateral heterogeneities in the mechanical properties of bone. Modeling wave propagation in the skull of dolphins contributes to our understanding of how their sound localization and echolocation mechanisms work. Dolphins are known to be highly effective at localizing sound sources; in particular, they have been shown to be equally sensitive to changes in the elevation and azimuth of the sound source, while other studied species, e.g. humans, are much more sensitive to the latter than to the former. A laboratory experiment conducted by our team on a dry skull [2] has shown that sound reverberated in bones could possibly play an important role in enhancing localization accuracy, and it has been speculated that the dolphin sound localization system could somehow rely on the analysis of this information. We employ our new numerical model to simulate the response of the same skull used by [2] to sound sources at a wide and dense set of locations on the vertical plane. This work is the first step towards the implementation of a new tool for modeling source (echo)location in dolphins; in future work, this will allow us to effectively explore a wide variety of emitted signals and anatomical features.

3D Structure of Striations in the North Pacific

2021 ◽  
Author(s):  
YU ZHANG ◽  
YU PING GUAN ◽  
RUI XIN HUANG
Keyword(s):  
North Pacific ◽  
3D Structure ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Dimensional Structure ◽  
The North ◽  
Layer Analysis ◽  
Fluid Potential ◽  
The North Pacific

AbstractOcean striations are composed of alternating quasi-zonal band-like flows; this kind of organized structure of currents be found in all world’s oceans and seas. Previous studies have mainly been focused on the mechanisms of their generation and propagation. This study uses the spatial high-pass filtering to obtain the three-dimensional structure of ocean striations in the North Pacific in both the z-coordinate and σ-coordinate based on 10-yr averaged SODA3 data. First, we identify an ideal-fluid potential density domain where the striations are undisturbed by the surface forcing and boundary effects. Second, using the isopycnal layer analysis, we show that on isopycnal surfaces the orientations of striations nearly follow the potential vorticity (PV) contours, while in the meridional-vertical plane the central positions of striations are generally aligned with the latitude of zero gradient of the relative PV. Our analysis provides a simple dynamical interpretation and better understanding for the role of ocean striations.

scholarly journals Hexahedral Localization (HL): A Three-Dimensional Hexahedron Localization Based on Mobile Beacons

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Linlan Liu ◽  
Haili Zhang ◽  
Xiaotian Geng ◽  
Xin Shu
Keyword(s):  
Wireless Sensor Networks ◽  
Three Dimensional ◽  
High Accuracy ◽  
Wireless Sensor ◽  
Localization Accuracy ◽  
Localization Scheme ◽  
Future Work ◽  
Range Free ◽  
Mobile Beacons ◽  
Dimensional Range

In wireless sensor networks, localization is one of the fundamental technologies and is essential to its applications. In this paper, we propose a three-dimensional range-free localization scheme named hexahedral localization. In the scheme, the space is divided into a lot of hexahedrons. Then, all the unknown nodes are located by utilizing the perpendicular properties of the trajectory. The contribution of our scheme can be summarized into two points. First, it fills the gap of shortage of three-dimensional localization based on mobile beacons. Second, it brings in the outstanding localization accuracy. The simulation result reveals that this localization scheme has the relative high accuracy. At the end of the paper, the performance and error of our scheme are analyzed in aim of improving in the future work.

scholarly journals The role of spectral composition of sounds on the localization of sound sources by cats

2013 ◽  
Vol 109 (6) ◽  
pp. 1658-1668 ◽  
Author(s):  
Daniel J. Tollin ◽  
Janet L. Ruhland ◽  
Tom C. T. Yin
Keyword(s):  
Sound Localization ◽  
Spectral Composition ◽  
Power Spectra ◽  
Sound Sources ◽  
Gaze Shift ◽  
Localization Accuracy ◽  
Low Pass ◽  
Localization Performance ◽  
High Pass

Sound localization along the azimuthal dimension depends on interaural time and level disparities, whereas localization in elevation depends on broadband power spectra resulting from the filtering properties of the head and pinnae. We trained cats with their heads unrestrained, using operant conditioning to indicate the apparent locations of sounds via gaze shift. Targets consisted of broadband (BB), high-pass (HP), or low-pass (LP) noise, tones from 0.5 to 14 kHz, and 1/6 octave narrow-band (NB) noise with center frequencies ranging from 6 to 16 kHz. For each sound type, localization performance was summarized by the slope of the regression relating actual gaze shift to desired gaze shift. Overall localization accuracy for BB noise was comparable in azimuth and in elevation but was markedly better in azimuth than in elevation for sounds with limited spectra. Gaze shifts to targets in azimuth were most accurate to BB, less accurate for HP, LP, and NB sounds, and considerably less accurate for tones. In elevation, cats were most accurate in localizing BB, somewhat less accurate to HP, and less yet to LP noise (although still with slopes ∼0.60), but they localized NB noise much worse and were unable to localize tones. Deterioration of localization as bandwidth narrows is consistent with the hypothesis that spectral information is critical for sound localization in elevation. For NB noise or tones in elevation, unlike humans, most cats did not have unique responses at different frequencies, and some appeared to respond with a “default” location at all frequencies.

scholarly journals A Comprehensive Analysis of Allostery in 14-3-3 ζ Docking Proteins using the Spatial Convolution Model (SCM)

2021 ◽  
Author(s):  
Leroy K. Davis
Keyword(s):  
Wave Propagation ◽  
Local Density ◽  
Three Dimensional ◽  
Interaction Strength ◽  
Resonance Energy ◽  
Harmonic Oscillators ◽  
Dimensional Structure ◽  
Elastic Media ◽  
Residue Interaction ◽  
Convolution Model

The Spatial Convolution Model (SCM) analyzes allostery based on the spatial evolution of the docking protein elastic media, whereby convolution of the media in response to wave propagation is solved as a function of Z fluctuations and backbone vibration modes. We show that although the elastic media is a complex three-dimensional structure allostery behaves as if it occurs along a stretched oscillating string, where inhomogeneities along the string effect local entropies responsible for ligand binding and transduction of allosteric waves. To identify inhomogeneities along the string, we ignored local density and tension changes during wave propagation and resolved helix wave and physical properties by applying molecular string and beam bending theories. Importantly, we show that allostery occurs at three major scales and that propagation of standing waves create a rolling entropy which drives entropy transfers between fields. Conversion of resonance energy to quantum harmonic oscillators allowed us to consider effects of damping and interactions with the surrounding media as well as to model effects of residue interaction strength on entropy transfer.

THREE DIMENSIONAL REFLECTION CONTROL

Geophysics ◽  
1938 ◽  
Vol 3 (4) ◽  
pp. 340-348 ◽  
Author(s):  
S. M. Rock
Keyword(s):  
Wave Propagation ◽  
Plane Wave ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Field Work ◽  
Angle Of Arrival ◽  
Wave Fronts ◽  
Reflected Wave ◽  
Wave Travel

A pattern is presented in which ΔT’s are obtained from intersecting lines of detectors. Assuming a) plane wave fronts at the detectors, and b) rectilinear wave propagation, formulas are presented for: (1) ψ, the angle of arrival of the reflected wave in the wave‐travel plane: i.e., the plane through the line of exploration and perpendicular to the reflecting plane; (2) θ the angle between the wave‐travel plane and a vertical plane through the line of exploration; (3) α, the dip component in the wave‐travel plane; (4) δ, the total dip; and (5) γ, the angle between direction of total dip and the line of exploration. Application of the pattern to field work is described.

The Role of the Vertical Dimension in Stereoscopic Vision

Perception ◽  
1982 ◽  
Vol 11 (4) ◽  
pp. 377-386 ◽  
Author(s):  
H Christopher Longuet-Higgins
Keyword(s):  
Three Dimensional ◽  
Vertical Plane ◽  
Vertical Dimension ◽  
Stereoscopic Vision ◽  
Dimensional Structure ◽  
Retinal Images ◽  
Horizontal Meridian ◽  
Visible Points ◽  
Quantitative Explanation

It is shown how the full three-dimensional structure of a scene may in principle be computed from a correlated pair of retinal images, when all that is known about the orientations of the two eyes is that the planes of their horizontal meridians accurately coincide. The vertical dimension plays a crucial role in the theory; visible points which lie on the horizontal meridian supply no information about the angle of convergence or the direction of gaze. (i) If the scene contains three or more nonmeridional points, not all lying in a vertical plane, then their positions in space are fully determined by the horizontal and vertical coordinates of their images on the two retinas. (ii) If just two nonmeridional points are visible, or more than two, lying in a vertical plane, then their retinal images admit, in general, just two distinct three-dimensional interpretations. One of these is usually unrealistic; but a choice between them may be perceptually difficult if the vertical plane containing the points is nearly perpendicular to the interocular axis. These results suggest that vertical disparities may play an important role in the binocular perception of absolute depth. Elsewhere (Mayhew, this issue) this suggestion is found to provide a quantitative explanation of Ogle's ‘induced effect’.

Orbital flow around a circular cylinder. Part 2. Attached flow at larger amplitudes

1993 ◽  
Vol 246 ◽  
pp. 397-418 ◽  
Author(s):  
John R. Chaplin
Keyword(s):  
Boundary Layer ◽  
Steady State ◽  
Numerical Model ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Flow Around A Cylinder ◽  
Ambient Flow ◽  
Recirculating Flow ◽  
Time Stepping ◽  
Attached Flow

A time-stepping numerical model of uniform circular orbital flow around a cylinder provides results which are compared with the steady-state predictions of a boundary-layer solution by Riley. At small amplitudes of motion excellent agreement is found in most respects, but in the numerical model the outer recirculating flow and related components of loading do not reach a steady state after any finite time. At a Stokes parameter β of 500, the boundary-layer approach remains reasonably accurate for amplitudes of motion up to about 8 % of the cylinder diameter; for amplitudes up to twice this at the same value of β the flow remains largely attached. The strength of the outer recirculating flow is enhanced by nonlinear interactions, but the computed nonlinear loading exceeds that observed in experiments. Flow visualization shows a three-dimensional structure in the flow, and it is argued that this has an important effect on the loading that cannot yet be predicted. A computed force component at a frequency of about 30 % of that of the ambient flow is related to the retrogressive motion of vortex structures around the cylinder.

scholarly journals Numerical simulation of acoustic signal propagation in underwater acoustic duct

2021 ◽  
Vol 2 (396) ◽  
pp. 122-133
Author(s):  
F. Legusha ◽  
◽  
Yu. Popov ◽  
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Numerical Model ◽  
Acoustic Signal ◽  
Water Channel ◽  
Vertical Plane ◽  
Signal Propagation ◽  
The Real ◽  
Target Force ◽  
Real Target

Object and purpose of research. The progress in numerical simulation methods significantly widens the capabilities of theoretical analysis in the tasks requiring extensive calculations and input data sets, like sound propagation at sea. This paper discusses the feasibility of a numerical model describing the physics of acoustic signal propagation in a deep-water channel. Materials and methods. Acoustic signal calculation is performed as per the ray-path theory with a numerical model taking into account depth-wise variations of sound velocity and seabed parameters. Main results. It was shown that depending on the vertical distribution of sound speed, the source depth and distance, the acoustic wave propagation direction can change over significant range of angles the in vertical plane. In this regard it is advisable to calculate the real target force of an object of complex geometry not only from heading angle in horizontal plane but also in terms of the possible range of angles in the vertical plane. Conclusion. Model-analyzed angles range of long-range wave propagation may be used for change estimation of object target force characteristics. Practical significance of the study lies in improving the methods of calculation of the real target force of complex shape objects in terms of state-of the art capabilities of simulating the propagation of acoustic signals conditions in the ocean.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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