<title>Virtual command center for distributed collaborative undersea warfare</title>

Where is the theory? Evaluating the theoretical frameworks described in decision support technologies

The Advanced Volume Visualization Display (AVVD) research program is a joint research program between the Fraunhofer Center for Research in Computer Graphics, Inc. and Innovative Research and Development Corp. It is dedicated the application of the human visual system to real-time visualization of high- resolution volumetric sensor data sets. The AVVD program has successfully demonstrated its application to undersea imaging using data from the Naval Undersea Warfare Center -- Division Newport's High Resolution Array (HRA), and from the Naval Surface Warfare Center -- Coastal System Stations's Toroidal Volume Search Sonar (TVSS).

A three-dimensional finite element model of a high-power, low-frequency ring-shell flextensional transducer [Sparton of Canada, Ltd., model 34A0610] has been developed for use with the ATILA code [Decarpigny etal., J. Acoust. Soc. Am. 78, 1499–1507 (1985)]. A three-dimensional model is needed to represent nonaxisymmetric vibrations that can occur in a dense sonar array. The model was derived from a two-dimensional axisymmetric model developed by Blottman [J. B. Blottman, Naval Undersea Warfare Center, New London Laboratory, Technical Memorandum No. 89-1090 (1989)]. In extending Blottman’s model to three dimensions, reasonable simplifications were made to minimize the number of elements required to faithfully represent the dynamical behavior of the transducer in the frequency range of interest. A description of the model and the results of in-air modal and in-water harmonic analyses will be presented. [Work sponsored in part by the Naval Postgraduate School and the Naval Undersea Warfare Center.] a) Lieutenant Commander, Brazilian Navy.

Previous investigations have shown that natural attenuation and biodegradation of chlorinated volatile organic compounds (VOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU-1), Naval Undersea Warfare Center, Division Keyport, Washington. The U.S. Geological Survey (USGS) has continued to monitor ground-water geochemistry to assure that conditions remain favorable for contaminant biodegradation. This report presents the ground-water geochemical and selected VOC data collected at OU-1 by the USGS during June 21-24, 2005, in support of long-term monitoring for natural attenuation. For June 2005, the strongly reducing conditions (sulfate reduction and methanogenesis) most favorable for reductive dechlorination of chlorinated VOCs were detected in fewer upper-aquifer wells than were detected during 2004. Redox conditions in ground water from the intermediate aquifer just downgradient of the landfill remained somewhat favorable for reductive dechlorination. Overall, the changes in redox conditions observed at individual wells have not been consistent or substantial throughout either the upper or the intermediate aquifers. In apparent contrast to changes in redox conditions, the chlorinated VOC concentrations were lower than previously measured in many of the piezometers in the northern phytoremediation plantation. The decrease in contaminant concentrations beneath the northern plantation and the end-product (ethane and ethene) evidence for reductive dechlorination are consistent with 2000-04 results. In the southern phytoremediation plantation, changes in chlorinated VOC concentrations were variable. Most notable was a substantial decrease in the sum of trichloroethene, cis-1,2-dichloroethene, and vinyl chloride concentrations at piezometer P1-9 from 75,000 to 1,000 micrograms per liter between 2004 and 2005. The high concentrations of the reductive dechlorination end-products ethane and ethene measured at the most contaminated sites (P1-6 and P1-7), as well as measurable concentrations at sites P1-9 and P1-10, are reliable evidence that reductive dechlorination of chlorinated VOCs is ongoing in the southern plantation. In the 10 passive-diffusion samplers deployed beneath the marsh stream, the highest chlorinated VOC concentrations measured were at a site (S-4) about midway along the sampled stream reach. In 2005, the sum of trichloroethene, cis-1,2-dichloroethene, and vinyl chloride concentrations increased nearly twofold in comparison to 2004. It is not certain that the apparent increase in concentrations is representative of site conditions. However, the chlorinated VOC concentrations have increased each time at the two most contaminated passive-diffusion sampler sites that have been sampled for multiple years. In the marsh stream, chlorinated VOC concentrations in surface water were low at the site (SW-S6) near the upgradient margin of the former landfill. Concentrations in the stream increased substantially after flowing past the southern phytoremediation plantation to the downstream site (MA-12). Overall, the 2005 data were consistent with previous findings of continued biodegradation of chlorinated VOCs in ground water, along with continued discharge of some chlorinated VOCs to surface water in the marsh stream.

Previous investigations have shown that natural attenuation and biodegradation of chlorinated volatile organic compounds (CVOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center (NUWC), Division Keyport, Washington. This report presents the ground-water geochemical and selected CVOC data collected at OU 1 by the U.S. Geological Survey (USGS) during June 17-20, 2003 in support of long-term monitoring for natural attenuation. Strongly reducing conditions favorable for reductive dechlorination of CVOCs were found in fewer upper-aquifer wells during June 2003 than were found during sampling periods in 2001 and 2002. Redox conditions in water from the intermediate aquifer just downgradient from the landfill remained somewhat favorable for reductive dechlorination. As was noted in previous monitoring reports, the changes in redox conditions observed at individual wells have not been consistent or substantial throughout either the upper or the intermediate aquifers. Compared to 2002 data, total CVOC concentrations in June 2003 were nearly unchanged in all northern plantation piezometers sampled, although the concentrations were historically low at two of those sites. Total CVOC concentrations decreased consistently in the southern plantation samples. Historically low total CVOC concentrations were observed in three of the piezometers sampled, and a two order-of-magnitude decrease in total CVOCs was observed at one of those sites. The observed decreases in CVOC concentrations appear to be in contrast with the 2003 redox data that suggested less favorable conditions for reductive dechlorination. The Navy and USGS plan to do more extensive data-collection and interpretation during 2004 to better understand and document possible changes in redox conditions and contaminant biodegradation.

The Maneuver Decision Aid (MDA) is a knowledge-based planner currently being developed at the US Naval Undersea Warfare Center. the goal of MDA is to generate an optimal next-maneuver recommendation, to support the submarine commander's decision making process which includes absorbing an extensive amount of complex information in the short time interval between maneuvers. The model for the maneuver generation process decomposes into three main parts: situation assessment, goal formulation, and constraint satisfaction. It is essential for an automated reasoning system in this domain to consider all factors and concerns in a given situation to put forth its best recommendation. A key aspect of this model is that all identified situation goals and constraints are represented and combined according to their varying degrees of importance. The authors describe how constraint ratings are evaluated and combined within an object-oriented blackboard framework. The focus is on how rated-constraints are formed, represented, and combined to provide optimal solutions. >

The authors adopt the Unmanned Undersea Vehicle(UUV), which has taken the shape of manta(Sohn et al. 2006). They call here it Manta-type Unmanned Undersea Test Vehicle(MUUTV). MUUTV is designed with the similar concept of U UV called Manta Test Vehicle(MTV), which was originally built by the Naval Undersea Warfare Center, USA(Lisiewicz and French 2000, Sirmalis et al. 2001, U.S. Navy 2004). The present study deals with evaluation of extreme motion of MUUTV at large attac k angles. Extreme motion contains, for example, rising and depth change due to operation of hovering thrusters attached to MUUTV, lateral motion due to ocean current applied to MUUTV at low advance velocity, and so on. Numerical simulation technique has been utilized. The previous mathematical model on manoeuvring motion of MUUTV(Bae et al. 20 09a) is basically adopted. Based on the results of present model experiment on ex treme motion, the mathematical model is revised and supplemented in order to describe extreme motion. The hydrodynamic derivatives related to extreme motion are obtained from present model experiment and the other derivatives are referred to previous work(Bae et al. 2009a).

: Detailed stress analyses were required of critical lifting fixture components used to support conformal sonar array assemblies in performance trials conducted in 2008 at the Naval Undersea Warfare Center's Seneca Lake Test Facility. The stress analyses were necessary to ensure that the lifting fixture had sufficient structural integrity for the handling and operational phases of the trials. The targeted structural integrity levels required compliance with a minimum safety factor for each of the specific components investigated. The minimum safety factor was set to 5.0 based on the yield stress of each component. The stress analyses examined key screwed connections and weldments that join the lifting fixture to the array modules. The safety factors for the current component designs were determined and compared to the minimum requirement.

The US Naval Undersea Warfare Center and the Phillips Laboratory conducted a joint measurement campaign in Greenland during May 1991. The experiment included simultaneous operation of HF channel probe and commercial VHF meteor burst (MB) radio links. On May 13th, a significant polar cap absorption (PCA) event occurred which apparently resulted in blackout of the HF link for 12 hours. The VHF MB link provided effective message communication during the PCA even when simultaneous skywave links monitored by the HF probe were inoperative. The authors describe the experimental configuration, present both HF skywave and VHF MB link performance during the PCA, and compare measured results with predictions. >

After receiving only a trickle of interest over the past 50 years or so, biolocomotion has more recently attracted broader attention. In this chapter, biology-inspired highly maneuverable underwater vehicles (of ≈ 1 m Open image in new window length scale) that have achieved some degree of maturity are reviewed. Primarily, the Naval Undersea Warfare Center (NUWC) works are described. The nonlinear theoretical foundation of animal-inspired hydrodynamics and control is summarized. Low-speed propulsion (including hovering and maneuvering), control, and integration with sensors are considered. High-lift flapping-fin propulsion technology, cycle-averaged and olivo-cerebellar temporal control, integration with interaural time-differencing bio-sonar, and basin demonstration of utility are discussed. While numerous variables affect the mechanisms and integration of actuators, controllers, and sensors, the principles of self-regulating nonlinear dynamics provide a common and simplifying framework for the development of biorobotic vehicles. The salient features of these vehicles and their control design laws are tabulated. These emergent, low-speed platforms complement existing higher speed naval capabilities and are not substitutes for any existing mature system; in this sense, their utility depends on the imaginative nature of future operation concepts – a process that is unpredictable. The greater potential of the biorobotics approach is limited by a serious lack of progress in so-called strong artificial muscle technology, as well as by a lack of understanding of nonlinear temporal control and sensing and how they should be integrated. Application to utility has been facilitated where understanding of the underlying science has been mathematically formulated, and such formulation needs to be more widely emulated.

A low‐frequency, dual‐piston sonar transducer has been designed, built, and tested. This transducer uses a terbium–dysprosium magnetostrictive rod in combination with high‐temperature superconductive (HTS) coils as the driver element. Terbium–dysprosium, when operated at cryogenic temperatures, has the highest known magnetostrictive constant. In this transducer, two HTS coils, driven by a combined dc and ac signal, excite the magnetostrictive element. The resultant motion is transmitted through the vacuum cryostat enclosing the driver assembly to two head masses, which transmit the sound to the surrounding environment. The combination of the high magnetostriction and the absence of electrical dissipation in the HTS coils results in very high overall system efficiency. Modeling of this type of transducer shows overall efficiencies of 80% or more can be obtained. The driver assembly is cooled by a compact Stirling Cycle cryocooler. Performance testing in air and water show self‐resonance occurs at 520 and 430 Hz, respectively. The overall system design, as well as measurements of acoustic output and efficiency, will be presented. [This project was funded by The Naval Undersea Warfare Center, New London, CT, through the Small Business Innovative Research (SBIR) Program.]

Previous investigations have shown that natural attenuation and biodegradation of chlorinated volatile organic compounds (CVOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center (NUWC), Division Keyport, Washington. The U.S. Geological Survey (USGS) has continued to monitor ground-water geochemistry to assure that conditions remain favorable for contaminant biodegradation. This report presents the ground-water geochemical and selected CVOC data collected at OU 1 by the USGS during June 11-14, 2001 in support of the long-term monitoring for natural attenuation. Overall, the June 2001 data indicate that redox conditions in the upper aquifer remain favorable for reductive dechlorination of CVOCs because strongly reducing conditions persisted beneath much of the former landfill. Redox conditions in the intermediate aquifer down gradient of the landfill appear to have become more favorable for reductive dechlorination because June 2001 dissolved hydrogen concentrations indicated strongly reducing conditions there for the first time. Although changes in redox conditions were observed at certain wells during 2001, a longer monitoring period is needed to ascertain if phytoremediation activities are affecting the ground-water chemistry. A minor change to future monitoring is proposed. Filtered organic carbon (previously referred to as dissolved, and defined as that which passes through a 0.45-micrometer membrane filter) should be analyzed in the future rather than unfiltered (previously referred to as total) organic carbon because the filtered analysis may be a better measure of bioavailable organic carbon. Unfiltered and filtered organic carbon data were collected during June 2001 for comparison. Filtered organic carbon data collected in the future could be reasonably compared with historical unfiltered organic carbon data by multiplying the historical data by a factor of about 0.9.

Efficient and accurate mathematical codes for the prediction of underwater sound propagation are a critical component of SONAR system development and operation. The goal of the research presented herein is to develop, implement, and verify an efficient and rigorous coupled-mode solution for acoustic wave propagation in shallow water range-dependent environments. A theoretical framework involving a range-expanded inner product for capturing the coupling between modes as they propagate through a horizontally-variable medium is presented. This framework includes a novel discretization of the range-dependent acoustic medium. A difference equations approach, which implements the inner product to account for non-adiabatic energy transfer between modes, is used to recursively compute reflection and transmission coefficients throughout the discretized environment. Increased efficiency is gained in the method due to the ability to compute coupling via closed-form algebraic expressions and in the application of asymptotic analysis to simplify the transmission and reflection coefficients. Results will be shown for a sample of waveguides with horizontally-variable bottom depth, along with comparable results from R. Evans’ COUPLE model and an FEM solution produced by ARL-UT. [This work was funded by the Naval Undersea Warfare Center, Newport Rhode Island.]

Manta형 무인잠수정(Manta-type Unmanned Undersea Test Vehicle, 이하 MUUTV라 함)은 Naval Undersea Warfare Center의 Manta Test Vehicle의 설계 및 운용 개념을 기초로 하여 제안되었다(손 등, 2006). 본 연구에서는 Feldman(1979)과 손 등(2006)의 6자유도 운동 수학모델을 이용하여 MUUTV의 조종운동 특성에 미치는 유체력미계수의 민감도 해석을 수행하였다. 민감도 해석 기법으로는 Sen(2000)이 제안한 방법을 채택하였다. 본 연구를 통하여 각각의 유체력미계수가 MUUTV의 조종운동 특성에 미치는 영향을 정량적으로 파악할 수 있었으며, 상대적으로 영향을 작게 미치는 유체력미계수가 포함된 항을 제거하여 조종운동 수치 시뮬레이션을 수행하여도 운동 추정이 가능함을 알 수 있었다. Manta-type Unmanned Undersea Test Vehicle(MUUTV) is based on the same design concept as Unmanned Undersea Vehicle called Manta Test Vehicle(MTV), which was originally built and operated by the Naval Undersea Warfare Center(Lisiewicz et al., 2000, Sirmalis et al. 2001). The authors carried out the sensitivity analysis of the response of manoeuvring motion of MUUTV to changes in hydrodynamic derivatives, In order to calculate the sensitivity indices of hydrodynamic derivatives on MUUTV, the method by Sen(2000) was adopted Basically the dynamic mathematical model with six degrees of freedom by Feldman(1979) is used but a little revised, refered to Sohn et al.(2006) and some experiment in circulating water channel. Through the present research, some hydrodynamic derivatives of significance are found out, and also the numerical simulation using simplified mathematical model based on result of sensitivity analysis is ascertained to be enough for prediction of manoeuvring characteristics of MUUTV.

Testing in indoor underwater acoustic test tanks can be limited by ambient noise and by reflections from the tank’s surfaces. The severity of reflection problems is related to a tank’s dimensions and the acoustic reflectivity of the tank’s sufaces. To reduce reflection problems, a tank may be enlarged, but in most cases, this solution is not acceptable. An alternative solution is to modify the reflectivity of the tank’s surfaces by adding an anechoic lining to the tank. A broad frequency (1 to 100 kHz) anechoic lining system was designed and developed for the 700 000 gallon Acoustic Test Facility at the Naval Undersea Warfare Center in Newport, RI. To accomplish broad frequency absorption, two parallel gradual transition absorbers are used: low-frequency, triangular wedges arranged in rows 6 in. apart and high-frequency molded pyramids spaced approximately 1 in. apart. Both the wedges and pyramids are fabricated from specially formulated, microvoided-polyurethane composites. The system is designed to provide 8 to 33 dB of echo reduction between 1 and 100 kHz. Measured prototype performance exceeded 10 dB at frequencies above 1.8 kHz. System acoustic design and materials development are discussed. The results of acoustic testing are presented and compared to design predictions.