The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Searching an accurate and effective simultaneous localization and mapping (SLAM) algorithm is fundamental to autonomous underwater vehicles (AUVs) to perform robust autonomous navigation. FastSLAM is one of the most popular SLAM algorithms. In spite of its wide applications, it still suffers from two major drawbacks, inconsistency and particle degeneration. In this paper, a modified FastSLAM algorithm...
Technique for improving the quality of holographic image of particle and method for refinement a position of its best focusing plane are discussed. The procedure of reconstruction the trajectory of plankton particle from video sequence of holograms is illustrated. Method for 2-D representing of 3-D holographic image is considered as a way to automation the procedure of extraction the information from...
In some countries, project certification is a requirement of national agencies for offshore wind projects. The purpose is reducing uncertain risk through project basic design to in-service phase, as well as to ensure operating reliability. This paper is to describe a certification system for offshore wind farm project published by DNV in 2012, Offshore Service Specification (OSS) 901. This system...
Dynamic coded cooperation (DCC) does not need extra transmission time scheduled for the relay, which is appealing to the bandwidth-limited high-delay underwater acoustic (UWA) environment. In this paper, we propose dynamic coded cooperative automatic repeat request (DCC-ARQ) protocol for multi-hop UWA networks. A transmission packet with multiple blocks is taken as a one-shot unit, where an erasure-correction...
In distributed MIMO (multiple-input-multiple-output)-HFSWR (high frequency surface wave radar), multiple detection modes are introduced to enrich the detection information, however making ionospheric clutter more complicated. In this paper, a distributed MIMO-HFSWR system involving three monostatic radars is introduced. Sea echo and ionospheric clutters from different paths are received simultaneously...
Rising fuel prices and regulations to reduce CO2 emission have become a strong driving force to push shipyards and ship owners to build and operate energy saving ships. To meet these increasing demands, many novel designs and devices have been developed for reducing drag or for improving propulsion efficiency of a ship in seaway. Furthermore, several approaches using passive or active oscillating...
One parallel underwater acoustic network (UAN) is designed to monitor the vortex induced vibration (VIV) of free span of subsea infield pipeline in the harsh deep water environment. The architecture consist of one mater node and several source node which one kind of dense network. One underwater Orthogonal Frequency Division Multiple Access (UOFDMA) scheme is proposed to meet with the multiple access...
The paper presents some experimental results of autonomous underwater navigation, based on the fusion of acoustic and inertial measurements. The work is in the framework of the Thesaurus project, funded by the Tuscany Region, aiming at developing techniques for systematic exploration of marine areas of archaeological interest through a team of Autonomous Underwater Vehicles (AUVs). The test was carried...
With the increasing development of underwater vision sensors, simultaneous localization and mapping (SLAM) based on stereo vision has become a hot topic in the areas of ocean investigation and exploration. In this paper, visual SLAM with a focus on stereo camera system is presented to estimate the motion of autonomous underwater vehicles (AUVs) and build the feature map of surrounding environment...
Multiuser underwater acoustic communication is one of the enabling technologies for the autonomous oceans sampling network (AOSN). Based on explicit relationship between fractional Fourier transform properties of chirp signal and its parameters, we proposed a new modulation and demodulation scheme named multicarrier-multiple chirp rate shift keying (MC-MCrSK). The scheme can support four users communication...
This paper presents the analyzed results of an integration of an offshore wind farm (OWF) and a seashore wave farm (SWF) connected to an onshore large power grid through a high-voltage direct-current (HVDC) link to simultaneously achieve power-fluctuation mitigation and dynamic-stability enhancement. The performance of the studied OWF is simulated by three equivalent aggregated doubly-fed induction...
T waves excited by earthquakes propagate along the SOFAR channel with low transmission loss, and therefore can be recorded on land-based seismic stations and hydrophones located thousands of kilometers away from earthquake epicenters. Early T-wave observations are mostly based on recordings by land-based stations due to the mechanics of the energy conversion of acoustic waves into seismic phases....
Several studies have been carried out to investigate the correlation between the spectral shape features of the beam attenuation coefficient and the particulate matter characteristics in seawater, but little attention has been paid to the spectral resolution of these measurements. For this reason, the potential of the new hyperspectral transmissometer VIPER (TriOS GmbH), with 1.7 nm spectral resolution,...
In order to estimate the thermal plumes discharged from Chinshan and Kuosheng nuclear power plants on the coast of north Taiwan, this study uses the thermal infrared data from Landsat 7 ETM+(Enhanced Thematic Mapper Surface Temperature) to contrast with the in-situ SST measurement for the intake/discharge ports of the nuclear power plants. The near-infrared (band 4) data of Landsat 7 ETM+ are firstly...
The proliferation of HF radar networks around the globe has made them a vital component of the ocean observing endeavor. There are approximately thirty-four nations with oceanographic HF radar networks, eight of which have over 10 radar stations in their network. Providing high quality measurements for sustained periods of time is of the utmost importance. The global HF radar network has been established...
Dependence on the prior magnetic map become one of the key problems which restrict the development of the geomagnetic navigation. This paper inspired from the animal navigation behavior which dispense with the priori geomagnetic map. First, we generalize the bio-inspired navigation process as a multi-objective problems. Then, present a stress evolution search AUV navigation model for the particularity...
Carbon dioxide emission into the atmosphere from the major point sources such as coal fired power plants, steel plants, cement industries triggered studies on its green house effects. Mineral carbonation is an option for storage of carbon dioxide in industrial waste materials by converting it into carbonates similar to the end products of natural weathering processes. Present study deals with carbonation...
This paper presents a first look at directional wave spectra measurements, and derived parameters, obtained using the Australian Coastal Ocean Radar Network WERA HF radar systems and the Seaview Sensing software package. Selected examples show that such measurements can be made and include bimodal and swell-dominated cases. Some issues limiting their availability and accuracy are discussed.
Time synchronization is of great significance in underwater acoustic (UWA) networks. Many functions, such as network protocol stack, sleep-scheduling, and localization, are based on time synchronization. Because underwater sound speed is comparatively slow, synchronization protocols encounter a long propagation latency problem, which differs from those in terrestrial sensor networks. As a result,...
Airborne bathymetric lidar (Light Detection and Ranging) systems measure the optical path (range and angle) between the sea surface and the seafloor. Lidar achieves this measurement by firing a laser from an aircraft and calculating the range based on the speed of light and the time it takes for the laser pulse to return. Measurements of photoelectrons at the photocathode of a returned laser pulse...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.