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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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Performance of centralized and distributed tyracking for multistatic ASW scenarios Performance of centralized and distributed tyracking for multistatic ASW scenarios

Date added: 06/01/2006
Date modified: 06/22/2012
Filesize: Unknown

Performance of centralized and distributed tyracking for multistatic ASW scenarios. NURC-FR-2006-001. June 2006.

Target tracking significantly improves the detection and localization performance of contact data; as such, it provides significant value added to the undersea surveillance processing chain. Centralized and distributed fusion architectures have complementary strengths: the former is best with high detection redundancy, high false alarm environments; the latter is best with low detection redundancy. Data fusion provides a robust surveillance picture that exceeds the performance of any given sensor in a field of like-performing sensors, and nearly matches the performance of the best-performing sensor when id performance dominates that of all other sensors. In all cases, simple track classification based on track duration, average speed, and heading stability provides additional performance gains.

Surface drift prediction in the Adriatic Sea using hyper-ensemble statistics on atmospheric, ocean and wave models: uncertainties and probability distribution areas Surface drift prediction in the Adriatic Sea using hyper-ensemble statistics on atmospheric, ocean and wave models: uncertainties and probability distribution areas

Date added: 05/01/2006
Date modified: 06/22/2012
Filesize: Unknown

Surface drift prediction in the Adriatic Sea using hyper-ensemble statistics on atmospheric, ocean and wave models: uncertainties and probability distribution areas. NURC-FR-2006-012. May 2006.

An increasing number of current models routinely provide weather forecasts and climate predictions, offering multiple options on resolutions, range, domains and derived fields. NATO requirements include reliable tactical knowledge and forecasts of the sea surface components, where potential mine threats have to be mitigated or avoided and where search and rescue efforts have to be optimized. These issues become more challenging and relevant when considering support for Expeditionary Warfare (in remote areas with limited access) and countering naval asymmetric warfare (need for high accuracy and reliability). The surface drift is the resultant of many different direct and indirect contributions of the atmosphere, the ocean and the sea surface itself. However, the prediction of the surface drift resultant still remains a challenge when the different components have competing contributions, like in coastal or near-shore areas. One of the possible solutions to address these issues is to migrate from the traditional deterministic approaches towards probabilistic-stochastic methodologies. When multiple models and data become available, the envisaged probabilisticstochastic alternative is the multi-model super-ensemble technique which uses an optimized combination of an ensemble of models. This technique has previously been demonstrated to improve forecast skills in the atmospheric and is applied here to the prediction of surface drift in the Adriatic. The technique combines optimally an atmospheric, an ocean and a wave model and is shown to outperform traditional forecast methods.

MX3 Trial Report: Percentage Clearance Trials with Autonomous Underwater Vehicles MX3 Trial Report: Percentage Clearance Trials with Autonomous Underwater Vehicles

Date added: 05/01/2006
Date modified: 06/22/2012
Filesize: Unknown

MX3 Trial Report: Percentage Clearance Trials with Autonomous Underwater Vehicles. NURC-FR-2006-007 / SR-445. May 2006.

This High Performance AUV (HPAUV) Experimentation Project was funded by the Allied Command Transformation (ACT) to assess the military value of Commercial-Off-The-Shelf (COTS) AUVs for Defense Against Terrorism (DAT) and Mine Countermeasures (MCM). The MX3 Sea Trial was conducted in November 2005 in La Spezia to evaluate the detection and classification effectiveness of currently available and state-of-the-art AUVs in MCM applications. Twelve AUVs (6 different models) were operated in four different target areas. The experiment demonstrated the maturity of the various systems and clearly illustrated their utility in enhancing traditional MCM in expeditionary operations.

Calibration of cardioid beamforming algorithms Calibration of cardioid beamforming algorithms

Date added: 05/01/2006
Date modified: 06/22/2012
Filesize: Unknown

Calibration of cardioid beamforming algorithms. NURC-FR-2006-003. May 2006.

Many nations are now using or considering cardioid towed arrays as their principle receive array in active low frequency sonar applications.A drawback of cardioid array beamforming is that it is not obvious how the obtained signal levels, after processing, relate to the hydrophone pressure level. Calibrated signal levels are important, for example, for the comparison of processed cardioid data with sonar model predictions or to measure the difference in performance between cardioid arrays and line arrays. In this report mathematical expressions are derived that allow, in the case of CW or LFM signals, calibration of the cardioid processed data. The validity of these expressions is demonstrated with simulated and real active sonar data.

Scattering from axially symmetric objects: theory, FEMLAB model implementation and results Scattering from axially symmetric objects: theory, FEMLAB model implementation and results

Date added: 04/01/2006
Date modified: 06/22/2012
Filesize: Unknown

Scattering from axially symmetric objects: theory, FEMLAB model implementation and results. NURC-FR-2006-010. April 2006.

The areas of operational relevance addressed by this report are proud and buried target detection and classification. Low frequency SONAR techniques, in the range below 50 kHz for typical mine like objects, have the potential of improving the detection and classification of buried and proud targets. The advantage associated with the low frequencies is that such signals can penetrate the outer shell of the illuminated target, and interact with its interior structure. Hence, low frequency echoes can be used to detect acoustically the presence of explosive inside a target, such as for example a mine or an improvised explosive device. The penetration of low frequency sound into the sediment makes it also possible to obtain echoes from completely buried targets. A fundamental disadvantage associated with the low frequencies is that the spatial resolution is too low to make imaging-like classification possible. For this reason, it is necessary to devise physics-based processing techniques, which can aid in the detection and classification of low frequency echoes. To develop such techniques, it is necessary to rely on a priori knowledge of the low frequency echo structure. Such knowledge can come from numerical simulations or from experimental data. On the other hand, particularly the initial phases of such a research require the availability of reliable target echo models, so that it becomes possible to conduct broadband studies for a variety of different targets, in an affordable amount of time. A numerically efficient modeling tool for the computation of echoes scattered by axially symmetric targets with internal structure is presented. This report presents the mathematical formulation on which the tool is based, implementation instructions, and verified numerical results.

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