scholarly journals Network Optimisation and Performance Analysis of a Multistatic Acoustic Navigation Sensor

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5718
Author(s):  
Rohan Kapoor ◽  
Alessandro Gardi ◽  
Roberto Sabatini
Keyword(s):  
Acoustic Waves ◽  
Navigation Systems ◽  
Sound Waves ◽  
Test Volume ◽  
Positioning Accuracy ◽  
Sensor Arrangement ◽  
Pvt Data ◽  
Acoustic Navigation ◽  
And Performance ◽  
Ranging Errors

This paper addresses some of the existing research gaps in the practical use of acoustic waves for navigation of autonomous air and surface vehicles. After providing a characterisation of ultrasonic transducers, a multistatic sensor arrangement is discussed, with multiple transmitters broadcasting their respective signals in a round-robin fashion, following a time division multiple access (TDMA) scheme. In particular, an optimisation methodology for the placement of transmitters in a given test volume is presented with the objective of minimizing the position dilution of precision (PDOP) and maximizing the sensor availability. Additionally, the contribution of platform dynamics to positioning error is also analysed in order to support future ground and flight vehicle test activities. Results are presented of both theoretical and experimental data analysis performed to determine the positioning accuracy attainable from the proposed multistatic acoustic navigation sensor. In particular, the ranging errors due to signal delays and attenuation of sound waves in air are analytically derived, and static indoor positioning tests are performed to determine the positioning accuracy attainable with different transmitter–receiver-relative geometries. Additionally, it is shown that the proposed transmitter placement optimisation methodology leads to increased accuracy and better coverage in an indoor environment, where the required position, velocity, and time (PVT) data cannot be delivered by satellite-based navigation systems.

О ТОЧНОСТИ ОПРЕДЕЛЕНИЯ КООРДИНАТ ПОДВОДНОГО МОДУЛЯ НА ОСНОВЕ ИЗМЕРЕННЫХ ПАРАМЕТРОВ ДВИЖЕНИЯ БУКСИРУЕМОЙ СИСТЕМЫ

2020 ◽  
Author(s):  
V.V. Kostenko ◽  
Yu.V. Vaulin ◽  
F.S. Dubrovin ◽  
O.Yu. Lvov
Keyword(s):  
Immersion Depth ◽  
Computational Algorithms ◽  
Navigation Systems ◽  
Short Baseline ◽  
Positioning Accuracy ◽  
Underwater Acoustic ◽  
Ground Speed ◽  
Cable Length ◽  
Acoustic Navigation

Буксируемый подводный модуль (БПМ) эффективно используется для решения задач, связанных с координированием подводных объектов, местоположение которых подлежит уточнению в процессе их детальногообследования. При этом большое значение имеет точность определения координат самого буксируемогомодуля относительно судна-буксировщика. Использование гидроакустических навигационных средств, вчастности систем с ультракороткой базой (ГАНС УКБ), ограничено вследствие помех, влияющих на качествосигналов в приемной антенне. Альтернативой служит метод определения координат БПМ на основе данныхтраекторных измерений параметров буксируемой системы. К числу последних относятся расчетные значенияпараметров кабеля связи в установившихся режимах буксировки, значения путевой скорости и путевого углабуксировщика, а также измеренные значения длины кабеля, глубины погружения и курса БПМ. В работе дансравнительный анализ различных вариантов вычислительных алгоритмов, позволяющих получить оценки точности определения координат БПМ в различных режимах стационарной буксировки и при наличии сбоев вработе навигационных средств.The towed underwater module (TUM) is a useful toolfor solving problems of the positioning of the underwaterobjects, the location of which must be clarified during its detailedinspection. Herewith, the accuracy of the determinationof the coordinates of the towed module itself relative tothe towing vessel is essential for such kind of problems. Theuse of underwater acoustic navigation means, the systemswith ultra-short baseline (USBL) in particular, are limiteddue to interference affecting the quality of the signals on thereceiving antenna. As an alternative, the method is proposedfor TUM positioning based on trajectory measurements ofparameters of the towed system, which may include calculatedvalues of communication cable parameters in steadystatetowing modes, values of ground speed and towing angle,as well as measured cable length, immersion depth, andTUM heading. The paper provides a comparative analysisof various versions of computational algorithms, which allowobtaining estimates of the TUM positioning accuracy indifferent modes of stationary towing and in the presence offailures in navigation systems operation.

ACOUSTIC NAVIGATION SYSTEMS

1964 ◽  
Vol 76 (6) ◽  
pp. 937-940
Author(s):  
UNDERSEA TECHNOLOGY
Keyword(s):  
Navigation Systems ◽  
Acoustic Navigation

Photoacoustic Nanotracers for Subsurface Applications: Opportunities and Challenges

2021 ◽  
Author(s):  
Jesus Manuel Felix Servin ◽  
Hala A. Al-Sadeg ◽  
Amr Abdel-Fattah
Keyword(s):  
Acoustic Waves ◽  
Oil And Gas ◽  
Continuous Wave ◽  
Tracer Tests ◽  
Oil And Gas Industry ◽  
Oil Reservoirs ◽  
Medical Community ◽  
Sound Waves ◽  
Time Data ◽  
Gas Industry

Abstract Tracers are practical tools to gather information about the subsurface fluid flow in hydrocarbon reservoirs. Typical interwell tracer tests involve injecting and producing tracers from multiple wells to evaluate important parameters such as connectivity, flow paths, fluid-fluid and fluid-rock interactions, and reservoir heterogeneity, among others. The upcoming of nanotechnology enables the development of novel nanoparticle-based tracers to overcome many of the challenges faced by conventional tracers. Among the advantages of nanoparticle-based tracers is the capability to functionalize their surface to yield stability and transportability through the subsurface. In addition, nanoparticles can be engineered to respond to a wide variety of stimuli, including light. The photoacoustic effect is the formation of sound waves following light absorption in a material sample. The medical community has successfully employed photoacoustic nanotracers as contrast agents for photoacoustic tomography imaging. We propose that properly engineered photoacoustic nanoparticles can be used as tracers in oil reservoirs. Our analysis begins by investigating the parameters controlling the conversion of light to acoustic waves, and strategies to optimize such parameters. Next, we analyze different kind of nanoparticles that we deem potential candidates for our subsurface operations. Then, we briefly discuss the excitation sources and make a comparison between continuous wave and pulsed sources. We finish by discussing the research gaps and challenges that must be addressed to incorporate these agents into our operations. At the time of this writing, no other study investigating the feasibility of using photoacoustic nanoparticles for tracer applications was found. Our work paves the way for a new class of passive tracers for oil reservoirs. Photoacoustic nanotracers are easy to detect and quantify and are therefore suitable for continuous in-line monitoring, contributing to the ongoing real-time data efforts in the oil and gas industry.

scholarly journals In-Body Ranging with Ultra-Wideband Signals: Techniques and Modeling of the Ranging Error

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Muzaffer Kanaan ◽  
Memduh Suveren
Keyword(s):  
Neural Networks ◽  
Human Body ◽  
Extreme Value Distribution ◽  
Generalized Extreme Value Distribution ◽  
Ultra Wideband ◽  
Wideband Signals ◽  
Ranging Error ◽  
And Performance ◽  
Ranging Errors ◽  
Wireless Capsule

Results about the problem of accurate ranging within the human body using ultra-wideband signals are shown. The ability to accurately measure the range between a sensor implanted in the human body and an external receiver can make a number of new medical applications such as better wireless capsule endoscopy, next-generation microrobotic surgery systems, and targeted drug delivery systems possible. The contributions of this paper are twofold. First, we propose two novel range estimators: one based on an implementation of the so-called CLEAN algorithm for estimating channel profiles and another based on neural networks. Second, we develop models to describe the statistics of the ranging error for both types of estimators. Such models are important for the design and performance analysis of localization systems. It is shown that the ranging error in both cases follows a heavy-tail distribution known as the Generalized Extreme Value distribution. Our results also indicate that the estimator based on neural networks outperforms the CLEAN-based estimator, providing ranging errors better than or equal to 3.23 mm with 90% probability.

A physically motivated approach for filtering acoustic waves from the equations governing compressible stratified flow

2008 ◽  
Vol 601 ◽  
pp. 365-379 ◽  
Author(s):  
DALE R. DURRAN
Keyword(s):  
Acoustic Waves ◽  
Large Scale ◽  
Mass Conservation ◽  
Simple Expression ◽  
Reference State ◽  
Small Scale ◽  
Sound Waves ◽  
State Equations ◽  
Planetary Scale ◽  
Atmospheric Motions

An incompressibility approximation is formulated for isentropic motions in a compressible stratified fluid by defining a pseudo-density ρ* and enforcing mass conservation with respect to ρ* instead of the true density. Using this approach, sound waves will be eliminated from the governing equations provided ρ* is an explicit function of the space and time coordinates and of entropy. By construction, isentropic pressure perturbations have no influence on the pseudo-density.A simple expression for ρ* is available for perfect gases that allows the approximate mass conservation relation to be combined with the unapproximated momentum and thermodynamic equations to yield a closed system with attractive energy conservation properties. The influence of pressure on the pseudo-density, along with the explicit (x,t) dependence of ρ* is determined entirely by the hydrostatically balanced reference state.Scale analysis shows that the pseudo-incompressible approximation is applicable to motions for which ${\cal M})$2 ≪ min(1,${\cal R})$2, where ${\cal M})$ is the Mach number and ${\cal R}$ the Rossby number. This assumption is easy to satisfy for small-scale atmospheric motions in which the Earth's rotation may be neglected and is also satisfied for quasi-geostrophic synoptic-scale motions, but not planetary-scale waves. This scaling assumption can, however, be relaxed to allow the accurate representation of planetary-scale motions if the pressure in the time-evolving reference state is computed with sufficient accuracy that the large-scale components of the pseudo-incompressible pressure represent small corrections to the total pressure, in which case the full solution to both the pseudo-incompressible and reference-state equations has the potential to accurately model all non-acoustic atmospheric motions.

scholarly journals Afferent and Efferent Aspects of Mandibular Sensorimotor Control in Adults Who Stutter

2013 ◽  
Vol 56 (6) ◽  
pp. 1774-1788 ◽  
Author(s):  
Ayoub Daliri ◽  
Roman A. Prokopenko ◽  
Ludo Max
Keyword(s):  
Sensorimotor Control ◽  
Group Differences ◽  
Sensitivity Threshold ◽  
Active Movement ◽  
Jaw Movements ◽  
Positioning Accuracy ◽  
Displacement Threshold ◽  
Anatomical Properties ◽  
And Performance ◽  
Movement Differences

Purpose Individuals who stutter show sensorimotor deficiencies in speech and nonspeech movements. For the mandibular system, the authors dissociated the sense of kinesthesia from the efferent control component to examine whether kinesthetic integrity itself is compromised in stuttering or whether deficiencies occur only when generating motor commands. Method The authors investigated 11 stuttering and 11 nonstuttering adults' kinesthetic sensitivity threshold and kinesthetic accuracy for passive jaw movements as well as their minimal displacement threshold and positioning accuracy for active jaw movements. They also investigated the correlation with an anatomical index of jaw size. Results The groups showed no statistically significant differences on sensory measures for passive jaw movements. Although some stuttering individuals performed more poorly than any nonstuttering participants on the active movement tasks, between-group differences for active movements were not statistically significant. Unlike fluent speakers, however, the stuttering group showed a statistically significant correlation between mandibular size and performance in the active and passive near-threshold tasks. Conclusions Previously reported minimal-movement differences were not replicated. Instead, stuttering individuals' performance varied with anatomical properties. These correlational results are consistent with the hypothesis that stuttering participants generate and perceive movements on the basis of less accurate internal models of the involved neuromechanical systems.

scholarly journals Sound-wave instabilities in dilute plasmas with cosmic rays: implications for cosmic ray confinement and the Perseus X-ray ripples

2020 ◽  
Vol 493 (4) ◽  
pp. 5323-5335 ◽  
Author(s):  
Philipp Kempski ◽  
Eliot Quataert ◽  
Jonathan Squire
Keyword(s):  
Cosmic Rays ◽  
Thermal Plasma ◽  
Acoustic Waves ◽  
Cosmic Ray ◽  
High Energy ◽  
Density Fluctuations ◽  
Sound Waves ◽  
X Ray ◽  
Acoustic Instability ◽  
Anisotropic Viscosity

ABSTRACT Weakly collisional, magnetized plasmas characterized by anisotropic viscosity and conduction are ubiquitous in galaxies, haloes, and the intracluster medium (ICM). Cosmic rays (CRs) play an important role in these environments as well, by providing additional pressure and heating to the thermal plasma. We carry out a linear stability analysis of weakly collisional plasmas with CRs using Braginskii MHD for the thermal gas. We assume that the CRs stream at the Alfvén speed, which in a weakly collisional plasma depends on the pressure anisotropy (Δp) of the thermal plasma. We find that this Δp dependence introduces a phase shift between the CR-pressure and gas-density fluctuations. This drives a fast-growing acoustic instability: CRs offset the damping of acoustic waves by anisotropic viscosity and give rise to wave growth when the ratio of CR pressure to gas pressure is ≳αβ−1/2, where β is the ratio of thermal to magnetic pressure, and α, typically ≲1, depends on other dimensionless parameters. In high-β environments like the ICM, this condition is satisfied for small CR pressures. We speculate that the instability studied here may contribute to the scattering of high-energy CRs and to the excitation of sound waves in galaxy-halo, group and cluster plasmas, including the long-wavelength X-ray fluctuations in Chandra observations of the Perseus cluster. It may also be important in the vicinity of shocks in dilute plasmas (e.g. cluster virial shocks or galactic wind termination shocks), where the CR pressure is locally enhanced.

scholarly journals Application of Updated Sage–Husa Adaptive Kalman Filter in the Navigation of a Translational Sprinkler Irrigation Machine

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1269 ◽  
Author(s):  
Kenan Liu ◽  
Wuyun Zhao ◽  
Bugong Sun ◽  
Pute Wu ◽  
Delan Zhu ◽  
...  
Keyword(s):  
Kalman Filter ◽  
Autonomous Navigation ◽  
Sprinkler Irrigation ◽  
The Self ◽  
Maximum Deviation ◽  
Navigation Systems ◽  
Adaptive Kalman Filter ◽  
Average Deviation ◽  
Positioning Accuracy ◽  
Promising Development

Autonomous navigation for agricultural machinery has broad and promising development prospects. Kalman filter technology, which can improve positioning accuracy, is widely used in navigation systems in different fields. However, there has not been much research performed into navigation for sprinkler irrigation machines (SIMs). In this paper, firstly, a self-developed SIM is introduced. Secondly, the kinematics model is established on the platform of the self-developed SIM, and the updated Sage–Husa adaptive Kalman filter, which is an accurate and real-time self-adaptive filtering algorithm, is applied in the navigation of the SIM with the aim of improving the positioning accuracy. Finally, experiment verifications were carried out, and the results show that the self-developed SIM has good navigation performance. Besides this, the influence of abnormal observations on the positioning accuracy of the system can be restrained by using the updated Sage–Husa adaptive Kalman filter. After using the updated Sage–Husa adaptive Kalman filter for the SIM, the maximum deviation between the SIM and the predetermined path is 0.18 m, and the average deviation is 0.08 m; these deviations are within a reasonable range. This proves that the updated Sage–Husa adaptive Kalman filter is applicable for the navigation of sprinkler irrigation machines.

scholarly journals Interaction of Flux Tubes with Sound Waves

1990 ◽  
Vol 142 ◽  
pp. 239-243
Author(s):  
C Uberoi
Keyword(s):  
Magnetic Flux ◽  
Sound Wave ◽  
Acoustic Waves ◽  
Landau Damping ◽  
Sound Waves ◽  
Plasma Parameters ◽  
Flux Tubes ◽  
Plausible Mechanism ◽  
Magnetic Flux Tubes ◽  
Radiative Damping

The Landau damping of sound waves in a plasma consisting of ensemble of magnetic flux tubes is discussed. It is shown that sound waves cannot be Landau damped in general but under certain restricted conditions on plasma parameters the possibility of absorption of these waves can exist. The possibility of radiative damping of the acoustic waves along the magnetic filaments is also discussed. It appears that the most plausible mechanism of damping of sound waves in a plasma consisting of magnetic filaments can be due to scattering of a sound wave by the filaments.

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