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New challenges in the area of experimental logistics, data visualization and data fusion are encountered in oceanographic research when the need to keep track of the location of multiple ships, moorings, gliders, drifters, and other platforms is combined with assimilating supporting data gathered off the Internet and inserted into the experimental framework. Showing that this can be done well is a...
Analysis of microstructure vertical profiles CTD (conductivity, temperature and depth) is a common method for characterizing environmental turbulent fluid dynamics. One of the objectives in analyzing high-resolution CTD profiles is to identify turbulent regions (patches) within the flow. Due to the instrumental noise of CTD measurements and the environmental characteristics, it is necessary a denoising...
We propose a method for combined noise suppression and target detection for 3-axial magnetometer measurements. Vector linear prediction is used to whiten the noise, and matched filters are used for detection. In a case study, we are able to extract a decision variable with an SNR of 20 dB from an input signal where the amplitude of the target is similar to the noise amplitude. A block-based adaptive...
In order to monitor fast and vigorous internal waves in the ocean NIOZ has previously developed two high sampling rate 'Fast Thermistor Strings'. Although the electronic set-up of these instruments was satisfactory, model 1 being very accurate and model 2 sampling very fast, several problems occurred, principally due to complex cabling and water intrusion. Therefore, a new model 3 was developed. Its...
Regional Cabled Observatories (RCOs) being planned today anticipate a twenty-five year operating life. Users expect the RCO to be operable a high percentage of the time, (i.e. to have high availability), while owners and operators require high reliability, in order to manage repair and maintenance costs. Meeting the requirements for power delivery, communications bandwidth, and control capability...
Since the sweep-spread carrier (S2C) technology uses broadband frequency swept carrier signals with high frequency-sweep rates, the instant frequencies of multipath components have different values, what create sufficient background for their separation in frequency domain. The paper shows that after filtering the receiving signal with a filter, matched to the S2C reference signal, the strength and...
The Networked autonomous littoral surveillance (NetALS) system is a wireless distributed bottom mounted sensor network being developed at DRDC Atlantic. NetALS will consist of a chain of bottom mounted sensor clusters that rely on ultrasonic communications in both synchronous time division and asynchronous frequency division schemes to transfer detection statistics from relativley cheap sensor nodes...
This paper discusses an extension to existing methods for tracking underwater targets in multistatic active sensor fields using the Probabilistic Data Association Filter with Amplitude Information (PDAFAI). Target strength distributions as a function of aspect of expected targets are used to develop a new characterization of the signal-plus-noise probability density function that can account for knowledge...
Clutter (e.g., reverberation and bottom structures) can lead to excessive false alarm rates (identifying clutter as submarines) in antisubmarine warfare (ASW) active sonar systems. False alarm reduction is an important marine challenge in an era where ASW has shifted from noisy submarines in deep waters to quiet submarines in highly cluttered littoral regions. In this paper, physically motivated image...
Intending to capture sea-bottom crustal deformations with high accuracy, we have been developing new technologies for seafloor geodetic observations with an AUV. This has led to the development of a small high-performance geodetic observation system and an ideal spherical acoustic transducer, both to be mounted on an AUV, and the tuning and evaluation tests of them have yielded good results.
SeaDataNet (2006 -2010) is a major Pan-European and EU-funded project, undertaken by the National Oceanographic Data Centres (NODQ and the Satellite Data Centres (SDC) of nearby all coastal states bordering the European seas. It focuses on interconnecting the data centres to provide integrated on-line access to the most comprehensive sets of multidisciplinary in-situ and remote sensing marine data,...
Free stream tidal turbines are a source of growing interest in the marine renewable energy field. Some designs use variable pitch blade control devices in order to maximize the efficiency of the turbines; however these are complex to design, construct and maintain under the severe load conditions sub sea devices experience. Adaptive materials have been used in the wind industry to create bend-twist...
Solid-phase adsorption toxin tracking (SPATT) is founded on the observation that when low levels of toxic dinoflagellates are present in the water column significant amounts of toxins are dissolved in seawater. Previous researchers demonstrated a lag between detection of dissolved toxins adsorbed onto porous synthetic resin, phytoplankton peak cell densities and highest toxin concentrations in shellfish...
In this paper, we describe a method of recording by combining back-illumination of in-line objects with an off-axis reference beam to produce low-aberration holograms. This is advantageous since at the reconstruction stage no extra means of compensation are required. Calculations have shown that the spherical aberration does not exceed 5% for objects from 100 to 200 mum at a wavelength of 0.532 mum,...
This paper will describe the development of Neutron Backscatter Scans, a widely recognized technique in the processing industry for use in novel subsea applications. Neutron Backscatter has been widely used for over 40 years to define tank inventories, gas/liquid interfaces, liquid/liquid interfaces and solid accumulations. The technique works by sweeping the outside of the vessel and non-intrusively...
Coastal sand bluffs and cliffs on the Atlantic seaboard of North America frequently regress, forcing home drawbacks and lighthouse relocation such as that facing homeowners at Madaket and the Sankaty Light on Nantucket. Whether the dominant cause of bluff and cliff calving is erosion of beach at the base from high tide waves or exceptional high water currents or if it is rainfall induced, increased...
OLRAC, a Cape Town based company has developed a fisheries software product, named Olfish. Olfish is capable of collecting, analyzing, plotting, mapping, reporting, tracing and transmitting all data related to commercial fishing operations. Data can be compressed, encrypted and digitally authenticated prior to transmission to the company ashore or to the relevant management authority. Olfish can be...
Carbon dioxide (CO2) exchange between the atmosphere and the Wadden Sea, a shallow coastal region along the northern Netherlands, has been measured from April 2006 onwards on a tidal flat and over open water. Tidal flat measurements were done using a flux chamber, and ship borne measurements using an equilibrator to determine the partial pressure of CO2 in the water. A strong response of CO2 exchange...
By analyzing and interpreting the newly acquired seismic profile supported by China national 973 investigation items and synthesizing the datum with other related geologic & geographic information, we discussed the complicated evolutionary history of northeastern South China Sea especially from Cenozoic period and its inner dynamical mechanism. And, we analyzed the convergent process of the Manila...
Previous attempts to model acoustic propagation in a shallow underwater channel using transmission line matrix (TLM) have been hampered by shortfalls in the basic formulation of an otherwise competent numerical modelling technique. Significant advances have been made in recent years and it is now possible to demonstrate the benefits of TLM in this application. Perfectly matched boundaries to limit...
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