Unmanned surface vehicles: An overview of developments and challenges

By searching the title, publisher, or authors of guide you in reality want, you can discover them rapidly. In the house, workplace, or perhaps in your method can be all best place within net connections. If you objective to download and install the guidance and control of ocean vehicles, it is utterly easy then, past currently we extend the colleague to buy and make bargains to download and install guidance and control of ocean vehicles therefore simple!

Guidance And Control Of Ocean Vehicles

Advances in global linear instability analysis of nonparallel and three-dimensional flows

The development of the One Atmosphere Uniform Glow Discharge Plasma has made it possible to cover the wings and fuselage of aircraft with a thin layer of glow discharge plasma at low energy cost. This plasma layer provides, through Lorentzian collisions, a purely electrohydrodynamic coupling between an electric field and the neutral gas in the boundary layer. This coupling is strong enough to cause aerodynamically significant acceleration and manipulation of the boundary layer and free stream flow, including re-attachment of flow to an airfoil at high angles of attack, and the peristaltic induction of neutral gas flow by a traveling electrostatic wave on the surface of a flat plate.

Aerodynamic flow acceleration using paraelectric and peristaltic electrohydrodynamic effects of a One Atmosphere Uniform Glow Discharge Plasma

The subject of ocean turbulence is in a state of discovery and development with many intellectual challenges. This book describes the principal dynamic processes that control the distribution of turbulence, its dissipation of kinetic energy and its effects on the dispersion of properties such as heat, salinity, and dissolved or suspended matter in the deep ocean, the shallow coastal and the continental shelf seas. It focuses on the measurement of turbulence, and the consequences of turbulent motion in the oceanic boundary layers at the sea surface and near the seabed. Processes are illustrated by examples of laboratory experiments and field observations. The Turbulent Ocean provides an excellent resource for senior undergraduate and graduate courses, as well as an introduction and general overview for researchers. It will be of interest to all those involved in the study of fluid motion, in particular geophysical fluid mechanics, meteorology and the dynamics of lakes.

https://assets.cambridge.org/97805218/35435/frontmatter/9780521835435_frontmatter.pdf

The Turbulent Ocean

Hydrodynamics of an advanced catamaran unmanned surface vehicle (USV) in shallow waters involving CFD-based modeling and simulation is described, in support of system identification and development of a physics-based control system for USV operations in coastal waters. The key objectives of the study are to develop the necessary CFD tool, validate it through comparison of computed results with results of field tests of the vehicle, and conduct a parametric study of the vehicle performance at different Froude numbers in calm water. The characteristics of the wave resistance, wave-hull interactions and free surface flow patterns around the hulls of the surface vehicle are also determined. The CFD tool will serve as a performance prediction tool for the USV.

Hydrodynamics of Advanced-hull Surface Vehicles

Internal waves in the ocean environment produce weak magnetic fields through induction as seawater is conductive. The induced field can be detected in measurements of the magnetic field using a sensitive magnetometer. Isolating the magnetic signature of these ubiquitous phenomena from geomagnetic and noise sources requires careful analysis. The experiment uses two fixed bottom mounted magnetometers, one on shore and the other underwater, and an underwater bottom mounted acoustic Doppler current profiler (ADCP). Raw signals are adjusted for any data corruption and anthropomorphic interference, such as large spike removal through Anderson functions. Wavelet decomposition is used to automatically detect spikes in the magnetic data and allows for their replacement through interpolation schemes. Then filtering techniques, including frequency-domain cancellation (FDC), are used to show the signature of the internal wave. These results are correlated with ADCP data to search for internal wave activity.

Isolating the magnetic signature of internal waves

Magnetic signals with a small signal-to-noise ratio are expected to be produced by internal waves in an ocean environment due to motion of dissolved salts. Although theoretically sound, the transient and varied nature of internal waves has made it difficult to characterize their magnetic signature. Previous work by the authors focused on the isolation of such internal wave signatures in a magnetic record, but left behind many questions and the need for corroboration. The extension of this work rectified issues in the previous magnetic processing and provided processing techniques of water particle velocity data for insightful correlations. Data was collected using multiple magnetometers and acoustic doppler current profilers (ADCPs). After data processing was completed, a multi-variate analysis algorithm was used to optimize the correlations between magnetic and water particle velocity signals. Correlations above 90% were achieved for multiple datasets.

Optimizing Correlations of Magnetic and Hydrodynamics Signatures

Pitching and heaving motions of an air-cushion vehicle, such as a surface effect ship (SES), in response to wave encounters as it transitions through a transforming wave-field such as in the near-shore zone are considered. The vehicle maintains a pressurized air cushion between its two side hulls and the deck hull. In head seas, the passage of waves across the length of the ship results in variations in the air cushion pressure and in associated compressibility effects. In view of the shallow draft of the vehicle, the primary forcing is considered to be due to the compressible dynamics of the air in the cushion in response to the evolving wave field. Through solution of equations governing the response of the vehicle to unsteady changes in the air cushion pressure due to encounter with transforming waves in head seas is described. Coupled unsteady equations for heave and pitch are solved to determine response to passage through transforming head seas. Complementary laboratory experiments are described. Wave transformation from deep waters to the beach is determined using the model of Dally et al. (1985) and the shallow-water SWAN model. The transformations of a regular wave over a beach slope and of an offshore JONSWAP spectrum are computed and used as incident wave fields to determine the response of the vehicle in transitioning at speed U in head seas. The heave and pitch motions for a specific SES are computed as functions of time and frequency in a coordinate system moving with the transitioning vehicle. The characteristics of the vehicle response to a regular transforming monochromatic wave and to transforming irregular waves are determined. Heave and pitch motion of a selected SES, driven by cushion dynamics suggest how the vibrational energy is spread over a range of frequencies as the vehicle proceeds through this evolving wave field. A test platform involving a scaled model SES instrumented with an inertial motion unit to measure six-degrees-of-freedom motions of the vehicle, a pressure gauge to record the air cushion pressure and a custom flex sensor to measure bow skirt deflections due to wave impacts is used to study the vehicle response to transforming waves in laboratory experiments. Results of low Froude number experiments show that the heave, pitch and air cushion excess pressure fluctuations increase as mean air cushion excess pressure increases. The results are compared with the computations described above.Copyright © 2012 by ASME

Motion of an Air-Cushion Vehicle in Transforming Nearshore Head Seas

The goal of our research is to characterize the performance of an off-the-shelf Overhauser Sentinel magnetometer when towed by an autonomous underwater vehicle (AUV). It is well known that the hydrodynamic motion of conductive seawater in the oceans through the earth's field leads to electrodynamic phenomena based on the dynamo effect. Oceanographic features such as surface waves, currents, and internal waves, produce electromagnetic signatures, which could be sensed and detected with an instrument that has the appropriate resolution and accuracy. This paper presents our preliminary work on characterizing the performance of the magnetic sensor, and the impact of the presence of a REMUS 100 AUV on it. The performance characterization consists of two major considerations: orientation sensitivity and vehicle anomaly sensitivity. Time-series and power spectral density results obtained from the orientation and vehicle sensitivity measurements will be presented.

Manhar R. Dhanak

Papers

Hydrodynamics of Advanced-hull Surface Vehicles

Isolating the magnetic signature of internal waves

Optimizing Correlations of Magnetic and Hydrodynamics Signatures

Motion of an Air-Cushion Vehicle in Transforming Nearshore Head Seas

Characterizing magnetic sensors and magnetic noise of AUVs