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The environmental impacts of tidal stream energy extraction are not yet understood. What is known is that the ecological effects of tidal mixing are both direct and indirect. The direct effects of changes in mixing affect the location and timing of foraging of a range of marine animals. The indirect effects of changes in mixing influence the amount and location of primary production. The complexity...
Under water acoustic communication using Multi Input Multi Output (MIMO) systems was shown to be effective in exploiting the time and spatial diversity characteristics of the underwater acoustic communication channel (UWAC). However, Inter Symbol Interferences (ISI) caused by the multipath phenomenon of the MIMO channel, affects the communication system performances. Our work shows that by using the...
This paper outlines an active heave compensation system used in conjunction with a crown mounted compensator. The objective is to reduce the heave disturbance at the suspended load above sea floor using an active sub-system comprising controller, sensors and a suitable hydraulic power unit driving an actuator attached to the compensator. In this case the compensator system behaves much like a spring...
Many of the sampling methods used in oceanographic sciences today date back decades, if not centuries. Although there has been a marked change in how sampling for chemical oceanography is carried out it still relies on taking samples of seawater from a research vessel in most cases. Assessing processes on small timescales as well as transient events requires higher temporal and spatial resolution...
Underwater sensor networks (UWSNs) comprise sensor nodes that communicate over multiple wireless hops to perform collaborative tasks such as environmental monitoring, military surveillance, and oceanic exploration. Acoustic waves are used for underwater transmission, resulting in a communication channel that suffers from limited bandwidth, high delay, and high transmission loss. Existing data delivery...
The narrowband detector model used in passive sonars consists of a band-pass filter followed by a quadrature receiver, and so operates exclusively on signal power. The human ear suggests an alternative approach to narrowband detection based on signal phase, which is captured by phase locking in auditory nerve fibres. According to these principles, three "interval detectors" - detectors using...
Underwater acoustic networks are envisaged to be the enabling technology for oceanographic data collection, pollution monitoring, offshore exploration and tactical surveillance applications. Unique characteristics of underwater acoustic channels such as large propagation delays and high bit error rates pose a challenge to designing reliable and efficient communication protocols. In this paper, we...
A simple 2D analysis on a long flexible structure, which is used for the floating type offshore wind power plant, has been performed to know the basic hydroelastic behavior of the structure. The method is not time consuming to cover wide-range combinations of the incident angle and the period. Using this method, the hydroelastic behavior of the structure in oblique irregular waves is investigated...
In recent years there has been considerable effort to translate the techniques used to achieve performance gains in the RF community into similar performance gains in the underwater acoustic field. Initially, developments focused on moving away from single side band signals towards direct sequence spread spectrum, resulting in improved tolerance to fading, noise and reverb. More recently, attempts...
Because of device noises, bad sea state or incorrect ship parameter, multibeam bathymetry data easily conceal many outliers. In order to process such large amount of data, we must research an automatic and rapid and robust approach. We present an automatic algorithm for detecting outliers based on density of points. Firstly, each swath data are projected along orthogonal and side direction respectively...
In this paper, a signal processing method for high-speed underwater acoustic transmission of image is presented. It has two parts. Part 1 is underwater acoustic coherent communication signal processing. Part 1 includes 3 technical points. 1. Doppler shift compensation. Chirp signals are inserted between data packages. A correlation process between two copy correlation results gives more accurate estimation...
A use of a dual-tree discrete wavelet transform (DT DWT) to the problem of signal detection in underwater sound is proposed in this paper. By noted that there is no obvious distribution assumption can model underwater noise, an empirical model of noise constructed by the discrete wavelet transform (DWT) is applied to identify the signals. This DWT based model adapts with time and is treated as a baseline...
Thraustochytrids - lightly-pigmented estuarine and marine microheterotrophs, taxonomically aligned with heterokont algae - are of great biotechnological interest because they produce substantial amounts of polyunsaturated fatty acids (PUFAs) especially docosahexaenoic acid (DHA:6n3). In this study, twenty-seven strains, isolated from twenty mangrove areas in the Philippine archipelago, were mass-produced...
The National Oceanic and Atmospheric Administration (NOAA) is the premier civilian ocean agency in the United States. To meet its mission, the agency addresses coastal and ocean challenges on a daily basis focusing on issues ranging from fish stock assessments to coastal inundation. NOAA relies upon a broad science and technology enterprise that produces the products and services necessary to make...
The process of track initialization has two main parts: determining when a new contact of interest has appeared in the search region and computing an initial state estimate to be given to the tracking algorithm. The author has developed a new method for detecting the arrival of a new contact of interest in monostatic systems that partitions the detection level data into Hough Transform type bins....
Since early 90's, Canary Islands Archipelago represents a very important working area for operational oceanography in Europe. Spanish and other european research groups, joining common projects (ANIMATE, MERSEA, ALERMAC,...), have an important and multidisciplinary group of devices placed in the area: deep ocean mooring lines, ocean ODAS buoys, the long-time series station ESTOC,...all of them are...
Underwater acoustic channels are wideband in nature due to the fact that the signal bandwidth is not negligible with respect to the center frequency. OFDM transmissions over UWA channels encounter frequency-dependent Doppler drifts that destroy the orthogonality among OFDM subcarriers. In this paper, we propose a two-step approach to mitigating the frequency-dependent Doppler drifts in zero-padded...
The quality of the technical expertise of our young students tends to be gradually decreasing. There exist too many distractions like social climbing among their peers, expertise in athletic endeavors, and an excess of time and money. There exists the need to strengthen and enhance the scientific and technical literacy of our students. If there is excitement in an activity, the student becomes motivated...
Platelet TechnologyTM is a unique and innovative method of sealing and locating leaks in pressurised pipelines; and is adapted from the human body's own leak sealing method whereby platelets in the blood stream initiate the mechanism for sealing cuts and wounds. The technology involves the remote injection of discrete particles known as "PlateletsR" into a pipeline which are carried to the...
In response to the two major energy challenges of climate change and security of supply, there is increased interest in the extraction of energy from renewable sources. Marine renewables, including tidal stream power show great potential, however the economics of these technologies is currently less favourable than land based renewable energy technologies due to the challenge of working in the marine...
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