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Multi-vehicle teams are being used more and more frequently to solve increasingly complex problems [1, 2]. In order for the team to work effectively, the vehicles must communicate to coordinate their efforts. In applications with high quality communication links, the vehicles are able to operate almost as a single entity. But in more harsh and dynamic environments, such as underwater, communication...
This paper presents the theory of passive localization for underwater sources based on multipath arrival structures. The principles of channel modelling in Ray-theory, determination of eigenrays which connect source and receiver, the information of source range and source depth is included primarily in arrival angles and time delays. The weighted-subspace-fitting (WSF) technique is used to minimize...
Studying fish recognition has important realistic and theoretical significance to aquaculture and marine biology. Fish recognition is challenging problem because of distortion, overlap and occlusion of digital images. Previous researchers have done a lot of work on fish recognition, but the classification accuracy may be not high enough. Classification and recognition methods based on convolutional...
A series of experiments were conducted to investigate the effect of ventilation on supercavity around a supercavitating vehicle during water-entry. An elaborate facility equipped with a complete set of measurement and control system was built, and the supercavitating vehicle was typically set to be launched at 20 degrees angle with a speed of 70 m / s. Firstly, the experiment was carried out to investigate...
This paper proposed two methods to analyze marine riser, which is Finite Element Method (FEM) and Extended Kalman Filter (EKF) method. Due to environmental disturbances and ship motion, the occurrence of riser's large deflections will bring fatigue problems and propagation cracks, which will lead to environmental disasters. Compare the two methods to derive structural parameters of riser, such as...
This paper proposes a novel framework for detecting and localizing the transients corresponding to the shocks created by sediment impacts on a steel plate. Based on unsupervised hierarchical agglomeration of complex vibration spectra, the derived classification is available for bedload transport monitoring stations in underwater environement.
This work reviews a high-speed, direct modulation underwater optical communication link enabled by a combination of polarization and Orbital Angular Momentum (OAM) multiplexing techniques that results in a data rate of 12 Gbit/s. An efficient technique for combining and sorting multiple OAM modes is presented based on log-polar coordinate transformation diffractive phase only optics.
In this paper we introduce a method for increasing the autonomy of multiple autonomous underwater vehicles that are conducting an offshore seismic survey. The proposed method concerns the recovery phase that has been done manually in the past. The objective is when the recovery process starts, all the AUVs should autonomously reach the recovery cage, when several AUVs are stacked into the cage, it...
We propose a swarm control algorithm for unmanned vehicles that adapts to unexpected environments while making the optimal formation. Our proposed algorithm, “autonomous and adaptive control”, is inspired by the control mechanism of living organisms and reconciles adaptability under a complex and changing environment and optimality for the various purposes of the system. In this paper, we apply the...
This work presents the generation, dynamic phase modulation and phase detection of interfering composite optical vortices. This technique demonstrates a new method for encoding information onto an optical beam for potential use in underwater communication as well as sensing applications including object detection and channel characterization.
The Office of Technology, Planning, and Integration for Observation (TPIO) maintains gap analysis tools that are used to compare both observing system attributes and the National Oceanic and Atmospheric Administration (NOAA) User Observation Requirements to help answer NOAA-wide business questions regarding observational needs and investment. Using the information connected to NOAA products, a capabilities...
The MUSIC(MUltiple SIgnal Classification) method with high resolution is typically used to estimate far-field source bearing. When the source is located in the near-field, it can be applied by compensating the time-delay difference and the magnitude attenuation using spherical wave rules. However, it has a problem with complex calculations, such as eigen-decomposition of a matrix. In this paper, we...
An enhanced current meter was deployed in the Antarctic in March, 2017, to measure vertical heat flux in the deep ocean. The purpose of this measurement of flux is to understand how mixing of dense Weddell Sea Bottom Water becomes Antarctic Bottom Water (AABW), the densest water of the Atlantic Ocean outside of trenches. Deep mixing is one of the problems that is not yet well understood despite its...
Marine pollution caused by oil spills — the release of petroleum hydrocarbons — poses a major threat to marine environments. This has become increasingly true also in the Arctic, where reduced sea ice extent has made Arctic oceans more accessible for industry and tourism-related ship traffic. To minimize the environmental impacts of an oil spill, it is important to identify the source and monitor...
Side scan sonar (SSS) is a vital sensor for autonomous underwater vehicles (AUVs) to do ocean survey. Many methods have been proposed to carry out SSS image segmentation, among which machine learning algorithms provide outstanding performance. Machine learning algorithms like support vector machine (SVM) and convolutional neural networks (CNN) are the most used. When SVM is used to do pixel-level...
The surf-zone presents unique challenges and opportunities for observational oceanography. Physical and biogeochemical signals change quickly in and around breaking surface waves due to high magnitudes of momentum and mass transfer. Autonomous instruments can be challenging to deploy in this energetic zone. We are developing the Smartfin, a surfboard fin capable of measuring geolocated ocean chemistry...
Fish-as-a-Service (FaaS) is a business-to-business model offering monitoring services performed by a biomimetic fishlike drone. FaaS considers environmental, scientific, and business concerns when addressing marine monitoring, providing alternative methodology while preserving ocean resources. The key to FaaS is the ability to provide a low-cost, low-maintenance, high-endurance, agile sensor platform...
During the launching of the AUV especially in air-launching, the water entry problem is inevitable. The AUV will stir the flow field of surrounding fluid during the moving into water, while the fluid will act a strong force on the AUV in return, which may cause trajectory deflection problems or damage to their structure and inner components in severe cases. The water entry experiment of full-size...
In this paper, we present a novel approach for the sensing of erosive cavitation phenomena in underwater facilities. Cavitation phenomena are known for their destructive capacity of underwater structures and are caused by the pressure decreasing followed by an implosion when the cavitation bubbles find an adverse pressure gradient. Conventional cavitation detection techniques are based on passive...
An Arctic-capable coastal geomorphic change model was developed based on the open-source coastal geomorphic change model, Xbeach. In this paper, we describe an approach to make the 2D version of the Xbeach model Artic-capable by adding a heat transfer module which computes the temperature and the phase of the sediment and water (frozen or unfrozen). During execution of the overall model, the conventional...
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