Calculation of the sound velocity in stratified seawater based on a set of fundamental equations

Bardakov, R. N.; Kistovich, A. V.; Chashechkin, Yu. D.

doi:10.1134/s000143701003001x

Cited by 4 publications

(3 citation statements)

References 4 publications

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“…In practical oceanography, basic quantity values-density, sound velocity, or temperature-are measured directly and calculated by algorithms containing data of various parameters. A comparison of these values is used to estimate the error of field measurements [89].…”

Section: Basic Dimensional and Dimensionless Parameters Of The Drop I...mentioning

confidence: 99%

Intrusive and Impact Modes of a Falling Drop Coalescence with a Target Fluid at Rest

Chashechkin

Ilinykh

2023

Axioms

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The evolution of the falling drop substance transfer in a target fluid at rest was traced by high-speed video techniques. Two flow modes were studied: slow intrusive flow, when the KE of the drop was comparable or less than the available potential energy (APSE), and a fast impact flow, at a relatively high drop contact velocity. For the substance transfer visualization, a drop of alizarin ink solution at various concentrations was used. The use of transparent partially colored fluid allows tracing the drop matter motion in the bulk and on the fluid free surface. The traditional side and frontal view of flow patterns were registered and analyzed. In both flow modes, the substance of the drop partially remained on the free surface and partially went into the target fluid bulk, where it was distributed non-uniformly. In the intrusive mode, the drop substance partially remained on the surface, while the main mass of the drop flowed into the thickness of the target fluid, forming the lenticular colored domain. The intrusion was gradually transformed into an annular vortex. In the impact mode, the drop broke up into individual fibers during the coalescence, creating linear and reticular structures on the surface of the cavity and the crown. The flow patterns composed of individual fibers were rapidly rebuilt as the flow evolved and the splash emerged and decayed. The sizes of cavities and colored fluid domains were compared in different flow regimes as well. The total energy transfer and transformation impact on the flow structure formation and dynamics was revealed.

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Section: Basic Dimensional and Dimensionless Parameters Of The Drop I...mentioning

confidence: 99%

Intrusive and Impact Modes of a Falling Drop Coalescence with a Target Fluid at Rest

Chashechkin

Ilinykh

2023

Axioms

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“…For both types of acoustic sensors, the change in speed of sound, if this is not correctly dealt with, could result in inaccurate readings. The speed-of-sound in water is affected by water temperature, salinity, and pressure [10], which can change locally and therefore can be hard to calculate correctly for the entire path. Therefore, it is important to investigate how the vehicle reacts to noise and measurement dropouts when designing the feedback and control system.…”

Section: Motion Sensor Evaluationmentioning

confidence: 99%

“…However, to do this, the delay has to be known. The time delay might vary due to changes in the properties of water, which affects the speed of sound [10]. Therefore checking the stability and robustness regarding time delayed systems adds valuable knowledge when designing autonomous navigation systems.…”

Section: Introductionmentioning

confidence: 99%

A Quantitative Parametric Study on Output Time Delays for Autonomous Underwater Cleaning Operations

Sørensen

Benzon

Liniger

et al. 2022

JMSE

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Offshore pipelines and structures require regular marine growth removal and inspection to ensure structural integrity. These operations are typically carried out by Remotely Operated Vehicles (ROVs) and demand reliable and accurate feedback signals for operating the ROVs efficiently under harsh offshore conditions. This study investigates and quantifies how sensor delays impact the expected control performance without the need for defining the control parameters. Input-output (IO) controllability analysis of the open-loop system is applied to find the lower bound of the H-infinity peaks of the unspecified optimal closed-loop systems. The performance analyses have shown that near-structure operations, such as pipeline inspection or cleaning, in which small error tolerances are required, have a small threshold for the time delays. The IO controllability analysis indicates that off-structure navigation allow substantial larger time delays. Especially heading is vulnerable to time delay; however, fast-responding sensors usually measure this motion. Lastly, a sensor comparison is presented where available sensors are evaluated for each ROV motion’s respective sensor-induced time delays. It is concluded that even though off-structure navigation have larger time delay tolerance the corresponding sensors also introduce substantially larger time delays.

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Fault Tree Analysis of Sensor Technologies for Autonomous UUV Navigation

et al. 2022

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Calculation of the sound velocity in stratified seawater based on a set of fundamental equations

Cited by 4 publications

References 4 publications

Intrusive and Impact Modes of a Falling Drop Coalescence with a Target Fluid at Rest

Intrusive and Impact Modes of a Falling Drop Coalescence with a Target Fluid at Rest

A Quantitative Parametric Study on Output Time Delays for Autonomous Underwater Cleaning Operations

Fault Tree Analysis of Sensor Technologies for Autonomous UUV Navigation

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