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Formal Reports

Report of results of completed projects or major milestones either in scientific terms or in terms acceptable to a wider audience. Note: Unless linked to the full text, reports are only available to NATO member nations from designated distribution centres. 

Documents

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A comparison of measured and modelled acoustic signal excess during Noble Mariner 2012 A comparison of measured and modelled acoustic signal excess during Noble Mariner 2012

Date added: 11/26/2014
Date modified: 11/26/2014
Filesize: Unknown

A comparison of measured and modelled acoustic signal excess during Noble Mariner 2012. Jiang, Yong Min; Strode, Christopher. CMRE-FR-2014-022. November 2014.

In September 2012, mid-frequency acoustic signal excess measurements were conducted in the Gulf of Lions to validate the sonar performance of the Multistatic Tactical Planning Aid. Owing to the fact that the validity of an acoustic model and the quantity and quality of the environmental information have almost equal impact on the fidelity of sonar performance predictions, this study carries out a measurement and model comparison of the acoustic signal excess by using different categories of rapid environmental assessment inputs. Specifically, five different categories of ocean environmental information have been used, including 1) climatology, 2) a high-resolution regional ocean model, 3) a high-resolution regional ocean model initialized by survey ship data collection, 4) a high-resolution regional ocean model updated by assimilation of glider data and 5) gray-ship equivalent on-scene for an operation. The bathymetric data used were either from climatology or collected by a multi-beam system for the scientific validation. The comparison was performed on the data collected along both range dependent and range independent tracks, seven source-target ranges for each track, two source depths at each source-target range and three different receiver depths. The impacts of varying degrees of fidelity of environmental information, as well as the conditions/configurations for setting up the acoustic model, on signal-excess predictions are summarized.

Interim model comparisons with Artemis Interim model comparisons with Artemis

Date added: 11/11/2014
Date modified: 11/11/2014
Filesize: Unknown

Interim model comparisons with Artemis. Harrison, Chris H. ; Schäfke, Alexandra; Strode, Christopher. CMRE-FR-2014-020. October 2014.

This report is a supplement to a report that documents recent changes to the sonar performance model, Artemis, to include convergence and caustic effects in a range-dependent environment [Harrison, CMRE-FR-2014-014]. Here favourable comparisons are made between Artemis and the well-established models Bellhop and RAM.

Decision support for counter-piracy operations: analysis of correlations between attacks and METOC conditions using machine learning techniques Decision support for counter-piracy operations: analysis of correlations between attacks and METOC conditions using machine learning techniques

Date added: 11/06/2014
Date modified: 11/06/2014
Filesize: Unknown

Decision support for counter-piracy operations: analysis of correlations between attacks and METOC conditions using machine learning techniques. Bombara, Giuseppe; Coccoccioni, Marco; Osler, John C.; Grasso, Raffaele. CMRE-FR-2014-019. October 2014.

Correlation between Meteorological and Oceanographic (METOC) data and sea piracy attacks in the Horn of Africa/Indian Ocean area is assessed and optimally exploited by using a machine learning approach based on the concept of a one-class classifier. The trained algorithms and METOC forecast models are used as inputs to forecast the piracy risk related to environmental conditions over the region of interest. Performance evaluation strategies are provided to assess the goodness of piracy risk maps used in daily counter piracy operation support. The research, through a rigorous analytical/statistical approach, confirms the existence of the correlation between METOC and sea piracy attacks and the algorithm evaluation procedure shows that the machine learning approach to the piracy risk prediction outperforms the classical threshold based method of modeling piracy group operational limits.

Impact of seabed geoacoustic gradients and roughness on acoustic transmission into the sediment Impact of seabed geoacoustic gradients and roughness on acoustic transmission into the sediment

Date added: 11/06/2014
Date modified: 11/06/2014
Filesize: Unknown

Impact of seabed geoacoustic gradients and roughness on acoustic transmission into the sediment. Nielsen, Peter L. CMRE-FR-2014-018. October 2014.

Low-frequency (<50 kHz) sonars have advantages in detecting buried objects compared to high-frequency sonars (>100 kHz) because of lower attenuation of the acoustic field in the seabed. This allows the acoustic field to interact with a buried object, which upon reception may be used for detection and classification. The low attenuation is not the only environmental parameter that increases the probability of buried object detection. Acoustic propagation above the critical angle of the seabed naturally increases the penetration of the field into the seabed, but also seabed roughness, volume inhomogeneities, and excitation of particular waves have been proposed to enhance the penetration, even at propagation angles below the critical angle. One mechanism rarely considered to contribute to the acoustic penetration is the gradients of the geoacoustic properties. In this report the impact of these gradients on the acoustic penetration ratio is investigated by numerical modeling. The penetration ratio is here defined as the ratio of the acoustic pressure received one meter into the seabed and the incident pressure at the water-seabed interface. A model to predict the depth and frequency dependent geoacoustic properties is applied to generate inputs to a modified version of the full-field range-dependent propagation model RAM. The geoacoustic model has been validated against independent seabed models and data, and the acoustic model is well established in the underwater acoustics community, and is known to produce results at high fidelity level. The synthetic environment is intended to mimic an operational condition for the newly developed low-frequency mine hunting sonar at CMRE. Significant increase in penetration depth is observed when a geoacoustic profile is used compared to a seabed with the maximum constant properties of the profile. The impact of roughness on the penetration depth is also investigated by generating a rough water-seabed interface from a power law with parameters extracted from experimental data. Here the geoacoustic properties are assumed constant in depth. Minimum impact of the water seabed roughness on penetration ratio is observed in this case.

Sensor data management to achieve information superiority in maritime situational awareness Sensor data management to achieve information superiority in maritime situational awareness

Date added: 11/06/2014
Date modified: 11/06/2014
Filesize: Unknown

Sensor data management to achieve information superiority in maritime situational awareness. Cimino, Giampaolo; Arcieri, Gianfranco; Horn, Steven A.; Bryan, Karna. CMRE-FR-2014-017. October 2014.

This report describes the data handling process set up at the NATO Science & Technology Organization (STO) Centre for Maritime Research and Experimentation (CMRE) which includes sensor data acquisition, processing, storage and access in support of the Maritime Situational Awareness (MSA) project. The Database Management System (DBMS) and the way in which sensor data is acquired and loaded using a database access layer framework for client applications is described. The system has been designed and developed to cope with extremely large data volumes generated by sensors and it is the foundation for supporting the CMRE MSA Service Oriented Architecture and the Fusion on Demand concept. Many aspects of this system are then analyzed: data sensor parsing, real-time database loading, database structure, database data extraction (real-time and historical). This analysis is supported with performance figures for the use of the system with real data sets. This analysis demonstrates that the system is aneffective way to deliver relevant information to MSA decision makers. The whole system is currently deployed at CMRE.

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