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JournalISSN: 0029-8018

Ocean Engineering 

About: Ocean Engineering is an academic journal. The journal publishes majorly in the area(s): Hull & Drag. It has an ISSN identifier of 0029-8018. Over the lifetime, 10265 publication(s) have been published receiving 161342 citation(s).
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Journal ArticleDOI
Rongxin Cui1, Rongxin Cui2, Shuzhi Sam Ge2, Bernard Voon Ee How2  +1 moreInstitutions (2)
Abstract: This paper is concerned with the leader–follower formation control of multiple underactuated autonomous underwater vehicles (AUVs). In the proposed leader–follower control, the follower tracks a reference trajectory based on the leader position and predetermined formation without the need for leader's velocity and dynamics. This is desirable in marine robotics due to weak underwater communication and low bandwidth. A virtual vehicle is constructed such that its trajectory converges to the reference trajectory of the follower. Position tracking control is designed for the follower to track the virtual vehicle using Lyapunov and backstepping synthesis. Approximation-based control technique is employed to handle the model parametric uncertainties and unknown disturbances for the follower. The residual error between vehicles within the formation is proven to converge to a bounded compact set and control performance is guaranteed by suitably choosing the design parameters. Extensive simulations are provided to demonstrate the effectiveness of the approaches presented.

442 citations

Journal ArticleDOI
TL;DR: Underwater Wireless Sensor Networks (UWSNs) are expected to support a variety of civilian and military applications and can only be interpreted meaningfully when referenced to the location of the sensor, making localization an important problem.
Abstract: Underwater Wireless Sensor Networks (UWSNs) are expected to support a variety of civilian and military applications. Sensed data can only be interpreted meaningfully when referenced to the location of the sensor, making localization an important problem. While Global Positioning System (GPS) receivers are commonly used in terrestrial WSNs to achieve this, this is infeasible in UWSNs as GPS signals do not propagate through water. Acoustic communications is the most promising mode of communication underwater. However, underwater acoustic channels are characterized by harsh physical layer conditions with low bandwidth, high propagation delay and high bit er

387 citations

Journal ArticleDOI
Abstract: The Nitinol alloys are based on the intermetallic compound TiNi. Alloys on the nickel-rich side of stoichiometry contain a certain portion of the compound TiNi3 in equilibrium with TiNi and are hardenable. In other alloying variations some of the nickel is replaced with cobalt. When a near stoichiometric specimen is mechanically deformed below its martensitic transition temperature it retains this deformed shape indefinitely. Upon heating above its martensitic transition temperature, however, it rapidly reverts to the shape it had before deformation. Thus the material exhibits a “mechanical memory” effect. The martensitic transition temperature may be varied within wide limits by changing the composition of the alloy. Cobalt, in the formula TiNixCo1−x, is an effective substitution element for lowering the transition temperature. The resistance of some of the Nitinol alloys to corrosion in sea water has been evaluated by conducting high velocity impingement, cavitation-erosion, stress corrosion and crevice corrosion measurements. The results of these tests have shown these alloys to be quite resistant to marine corrosion. Combination of the unusual mechanical and corrosion properties exhibited by these alloys make them especially suitable for applications in ocean engineering.

330 citations

Journal ArticleDOI
Abstract: A new type of control law is developed to steer an autonomous underwater vehicle (AUV) along a desired path. The methodology adopted for path-following deals explicitly with vehicle dynamics. Furthermore, it overcomes stringent initial condition constraints that are present in a number of path-following control strategies described in the literature. Controller design builds on Lyapunov theory and backstepping techniques. The resulting nonlinear feedback control law yields convergence of the path-following error trajectory to zero. Simulation results illustrate the performance of the control system proposed.

281 citations

Journal ArticleDOI
Ty V. Wamsley1, Mary A. Cialone1, Jane McKee Smith1, J. H. Atkinson2  +1 moreInstitutions (2)
Abstract: A critical component of flood protection in some coastal areas is expected to be the potential contribution of wetlands to the lowering of surges as they propagate inland from the coast. Consequently, an accurate method to quantify the effect of wetlands on coastal surge levels is required. The degree to which wetlands attenuate surge is the subject of debate and difficult to assess. The potential of wetlands to reduce storm surge has typically been expressed as a constant attenuation rate, but the relationship is much more complex. A numerical storm surge model was applied to assess the sensitivity of surge response to specified wetland loss. Results suggest that wetlands do have the potential to reduce surges but the magnitude of attenuation is dependent on the surrounding coastal landscape and the strength and duration of the storm forcing. Numerical models that simulate the relevant physical processes can provide valuable information on how to best integrate wetlands into coastal protection plans. However, while the model applied for this study has displayed skill in estimating surges over wetlands, the formulations are missing key processes and model advancements are necessary.

269 citations

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