Science.gov

Sample records for autonomous underwater modeling

  1. Application of Sampling Based Model Predictive Control to an Autonomous Underwater Vehicle

    DTIC Science & Technology

    2010-07-01

    55 Application of Sampling Based Model Predictive Control to an Autonomous Underwater Vehicle Unmanned Underwater Vehicles (UUVs) can be utilized...the vehicle can feasibly traverse. As a result, Sampling- Based Model Predictive Control (SBMPC) is proposed to simultaneously generate control...inputs and system trajectories for an autonomous underwater vehicle (AUV). The algorithm combines the benefits of sampling- based motion planning with

  2. Dynamics modeling and simulation of autonomous underwater vehicles with appendages

    NASA Astrophysics Data System (ADS)

    Su, Yumin; Zhao, Jinxin; Cao, Jian; Zhang, Guocheng

    2013-03-01

    To provide a simulation system platform for designing and debugging a small autonomous underwater vehicle's (AUV) motion controller, a six-degree of freedom (6-DOF) dynamic model for AUV controlled by thruster and fins with appendages is examined. Based on the dynamic model, a simulation system for the AUV's motion is established. The different kinds of typical motions are simulated to analyze the motion performance and the maneuverability of the AUV. In order to evaluate the influences of appendages on the motion performance of the AUV, simulations of the AUV with and without appendages are performed and compared. The results demonstrate the AUV has good maneuverability with and without appendages.

  3. Development of a computational model for an underwater autonomous vehicle

    NASA Astrophysics Data System (ADS)

    Galls, Samuel Fernando

    This research includes the development of a computational model created to autonomously navigate a biomimetic underwater vehicle. The navigation procedure uses as input a set of vehicle geometric and state variables and from that it predicts the needed vehicle body deformations so that the vehicle can navigate through a set of given waypoints. The first task is to develop a two dimensional numerical simulation based on an unsteady panel method coupled with the vehicle dynamics. Numerous test cases spanning the range of possible conditions are processed with the current simulation and this data is subsequently used to train a neural network. The trained network can predict what body deflection time history is necessary for the vehicle to navigate a given set of waypoints. Validation results are presented that show the accuracy of the present flow solver and several test cases of autonomous navigation are presented to show the capabilities of the current method.

  4. Modeling and Model Identification of Autonomous Underwater Vehicles

    DTIC Science & Technology

    2015-06-01

    Approved by: Noel du Toit Thesis Advisor Douglas Horner Second Reader Garth V. Hobson Chair , Department of Mechanical and...wheel drive electric wheelchairs ,” unpublished. [9] M. Caccia, G. Indiveri and G. Veruggio, “Modeling and identification of open- frame variable

  5. Autonomous underwater pipeline monitoring navigation system

    NASA Astrophysics Data System (ADS)

    Mitchell, Byrel; Mahmoudian, Nina; Meadows, Guy

    2014-06-01

    This paper details the development of an autonomous motion-control and navigation algorithm for an underwater autonomous vehicle, the Ocean Server IVER3, to track long linear features such as underwater pipelines. As part of this work, the Nonlinear and Autonomous Systems Laboratory (NAS Lab) developed an algorithm that utilizes inputs from the vehicles state of the art sensor package, which includes digital imaging, digital 3-D Sidescan Sonar, and Acoustic Doppler Current Profilers. The resulting algorithms should tolerate real-world waterway with episodic strong currents, low visibility, high sediment content, and a variety of small and large vessel traffic.

  6. Dynamics modeling of a semi-submersible autonomous underwater vehicle with a towfish towed by a cable

    NASA Astrophysics Data System (ADS)

    Park, Jinmo; Kim, Nakwan

    2015-06-01

    In this paper, we employ a dynamics modeling method for investigating a multi-body dynamics system of semi-submersible autonomous underwater vehicles consisting of a towing vehicle operated near the water surface, a tow cable, and a towfish. The towfish, which is towed by a marine cable for the purposes of exploration or mine hunting, is modeled with a Six-Degree-of-Freedom (6-DOF) equation of motion that reflects its hydrodynamics characteristics. The towing cable, which can experience large displacements and deformations, is modeled using an absolute nodal coordinate formulation. To reflect the hydrodynamic characteristics of the cable during motion, the hydrodynamic force due to added mass and the drag force are imposed. To verify the completeness of the modeling, a few simple numerical simulations were conducted, and the results confirm the physical plausibility of the model.

  7. Fish and chips: implementation of a neural network model into computer chips to maximize swimming efficiency in autonomous underwater vehicles.

    PubMed

    Blake, R W; Ng, H; Chan, K H S; Li, J

    2008-09-01

    Recent developments in the design and propulsion of biomimetic autonomous underwater vehicles (AUVs) have focused on boxfish as models (e.g. Deng and Avadhanula 2005 Biomimetic micro underwater vehicle with oscillating fin propulsion: system design and force measurement Proc. 2005 IEEE Int. Conf. Robot. Auto. (Barcelona, Spain) pp 3312-7). Whilst such vehicles have many potential advantages in operating in complex environments (e.g. high manoeuvrability and stability), limited battery life and payload capacity are likely functional disadvantages. Boxfish employ undulatory median and paired fins during routine swimming which are characterized by high hydromechanical Froude efficiencies (approximately 0.9) at low forward speeds. Current boxfish-inspired vehicles are propelled by a low aspect ratio, 'plate-like' caudal fin (ostraciiform tail) which can be shown to operate at a relatively low maximum Froude efficiency (approximately 0.5) and is mainly employed as a rudder for steering and in rapid swimming bouts (e.g. escape responses). Given this and the fact that bioinspired engineering designs are not obligated to wholly duplicate a biological model, computer chips were developed using a multilayer perception neural network model of undulatory fin propulsion in the knifefish Xenomystus nigri that would potentially allow an AUV to achieve high optimum values of propulsive efficiency at any given forward velocity, giving a minimum energy drain on the battery. We envisage that externally monitored information on flow velocity (sensory system) would be conveyed to the chips residing in the vehicle's control unit, which in turn would signal the locomotor unit to adopt kinematics (e.g. fin frequency, amplitude) associated with optimal propulsion efficiency. Power savings could protract vehicle operational life and/or provide more power to other functions (e.g. communications).

  8. Autonomous Underwater Vehicle Thermoelectric Power Generation

    NASA Astrophysics Data System (ADS)

    Buckle, J. R.; Knox, A.; Siviter, J.; Montecucco, A.

    2013-07-01

    Autonomous underwater vehicles (AUVs) are a vital part of the oceanographer's toolbox, allowing long-term measurements across a range of ocean depths of a number of ocean properties such as salinity, fluorescence, and temperature profile. Buoyancy-based gliding, rather than direct propulsion, dramatically reduces AUV power consumption and allows long-duration missions on the order of months rather than hours or days, allowing large distances to be analyzed or many successive analyses of a certain area without the need for retrieval. Recent versions of these gliders have seen the buoyancy variation system change from electrically powered to thermally powered using phase-change materials, however a significant battery pack is still required to power communications and sensors, with power consumption in the region of 250 mW. The authors propose a novel application of a thermoelectric generation system, utilizing the depth-related variation in oceanic temperature. A thermal energy store provides a temperature differential across which a thermoelectric device can generate from repeated dives, with the primary purpose of extending mission range. The system is modeled in Simulink to analyze the effect of variation in design parameters. The system proves capable of generating all required power for a modern AUV.

  9. Autonomous Underwater Navigation and Optical Mapping in Unknown Natural Environments

    PubMed Central

    Hernández, Juan David; Istenič, Klemen; Gracias, Nuno; Palomeras, Narcís; Campos, Ricard; Vidal, Eduard; García, Rafael; Carreras, Marc

    2016-01-01

    We present an approach for navigating in unknown environments while, simultaneously, gathering information for inspecting underwater structures using an autonomous underwater vehicle (AUV). To accomplish this, we first use our pipeline for mapping and planning collision-free paths online, which endows an AUV with the capability to autonomously acquire optical data in close proximity. With that information, we then propose a reconstruction pipeline to create a photo-realistic textured 3D model of the inspected area. These 3D models are also of particular interest to other fields of study in marine sciences, since they can serve as base maps for environmental monitoring, thus allowing change detection of biological communities and their environment over time. Finally, we evaluate our approach using the Sparus II, a torpedo-shaped AUV, conducting inspection missions in a challenging, real-world and natural scenario. PMID:27472337

  10. Autonomous Underwater Navigation and Optical Mapping in Unknown Natural Environments.

    PubMed

    Hernández, Juan David; Istenič, Klemen; Gracias, Nuno; Palomeras, Narcís; Campos, Ricard; Vidal, Eduard; García, Rafael; Carreras, Marc

    2016-07-26

    We present an approach for navigating in unknown environments while, simultaneously, gathering information for inspecting underwater structures using an autonomous underwater vehicle (AUV). To accomplish this, we first use our pipeline for mapping and planning collision-free paths online, which endows an AUV with the capability to autonomously acquire optical data in close proximity. With that information, we then propose a reconstruction pipeline to create a photo-realistic textured 3D model of the inspected area. These 3D models are also of particular interest to other fields of study in marine sciences, since they can serve as base maps for environmental monitoring, thus allowing change detection of biological communities and their environment over time. Finally, we evaluate our approach using the Sparus II, a torpedo-shaped AUV, conducting inspection missions in a challenging, real-world and natural scenario.

  11. Pipeline inspection using an autonomous underwater vehicle

    SciTech Connect

    Egeskov, P.; Bech, M.; Bowley, R.; Aage, C.

    1995-12-31

    Pipeline inspection can be carried out by means of small Autonomous Underwater Vehicles (AUVs), operating either with a control link to a surface vessel, or totally independently. The AUV offers an attractive alternative to conventional inspection methods where Remotely Operated Vehicles (ROVs) or paravanes are used. A flatfish type AUV ``MARTIN`` (Marine Tool for Inspection) has been developed for this purpose. The paper describes the proposed types of inspection jobs to be carried out by ``MARTIN``. The design and construction of the vessel, its hydrodynamic properties, its propulsion and control systems are discussed. The pipeline tracking and survey systems, as well as the launch and recovery systems are described.

  12. Intelligent mission planner for autonomous underwater vehicles

    NASA Astrophysics Data System (ADS)

    Vasudevan, C.; Ganesan, K.

    1994-03-01

    We describe the design of an architecture for an intelligent integrated mission planner for autonomous underwater vehicles (AUVs). Mission planning is an integral and important part of the software architecture of an AUV. Among the several functional modules of an AUV such as planner, controller, navigator, and perception, the planner plays the key role in generating, monitoring, and controlling of all mission tasks. In order to perform complex missions, the planner needs a wide range of knowledge and efficient reasoning techniques. Mission planning involves navigational planning, resource planning, safety planning, and mission-specific task planning. These functions require reasoning about the knowledge of the environment, vehicle, on-board resources, and mission tasks. The proposed design employs a mixture of hierarchical and heterarchical architectures. Case-based reasoning is employed for synthesizing mission plans. Among the different planner modules, design details of the navigational planner have been elaborated. The approach integrates advanced artificial intelligence techniques with AUV control architecture to make mission planning and execution simpler and flexible. The design takes into consideration the limited availability of AUV resources, scalability, and portability to other autonomous systems.

  13. Acoustic communications and autonomous underwater vehicles

    NASA Astrophysics Data System (ADS)

    Freitag, Lee; Grund, Matthew; Preisig, James; Stojanovic, Milica

    2004-05-01

    Acoustic communications systems used on autonomous underwater vehicles (AUVs) provide supervisory control, access to real-time data, and also allow multiple vehicles to cooperate in undertaking adaptive sampling missions. However, the use of acoustic systems on AUVs presents special challenges because of limited space for optimal placement of transducers, and potential conflicts with other acoustic systems such as side-scan sonars and transponders. In addition, radiated and structure-borne acoustic interference from thrusters and actuators reduces the sensitivity of on-board receivers. Recent work in acoustic communications and AUVs has included combining some navigation functions into communications equipment, development of operating modes that remove conflicts between different subsystems, design of vehicle components to avoid or remove interference, and other approaches to improving performance. While these efforts have been successful for specific installations, many challenges remain. This talk addresses problems and solutions for supervised and completely autonomous multi-vehicle communications to support complex AUV missions. Also presented are recent results which demonstrate that acoustic communications can be used successfully on a variety of AUV platforms for many different applications. [Work supported by ONR.

  14. Autonomous Underwater Vehicle Magnetic Mapping System

    NASA Astrophysics Data System (ADS)

    Steigerwalt, R.; Johnson, R. M.; Trembanis, A. C.; Schmidt, V. E.; Tait, G.

    2012-12-01

    An Autonomous Underwater Vehicle (AUV) Magnetic Mapping (MM) System has been developed and tested for military munitions detection as well as pipeline locating, wreck searches, and geologic surveys in underwater environments. The system is comprised of a high sensitivity Geometrics G-880AUV cesium vapor magnetometer integrated with a Teledyne-Gavia AUV and associated Doppler enabled inertial navigation further utilizing traditional acoustic bathymetric and side scan imaging. All onboard sensors and associated electronics are managed through customized crew members to autonomously operate through the vehicles primary control module. Total field magnetic measurements are recorded with asynchronous time-stamped data logs which include position, altitude, heading, pitch, roll, and electrical current usage. Pre-planned mission information can be uploaded to the system operators to define data collection metrics including speed, height above seafloor, and lane or transect spacing specifically designed to meet data quality objectives for the survey. As a result of the AUVs modular design, autonomous navigation and rapid deployment capabilities, the AUV MM System provides cost savings over current surface vessel surveys by reducing the mobilization/demobilization effort, thus requiring less manpower for operation and reducing or eliminating the need for a surface support vessel altogether. When the system completes its mission, data can be remotely downloaded via W-LAN and exported for use in advanced signal processing platforms. Magnetic compensation software has been concurrently developed to accept electrical current measurements directly from the AUV to address distortions from permanent and induced magnetization effects on the magnetometer. Maneuver and electrical current compensation terms can be extracted from the magnetic survey missions to perform automated post-process corrections. Considerable suppression of system noise has been observed over traditional

  15. Classification of underwater targets from autonomous underwater vehicle sampled bistatic acoustic scattered fields.

    PubMed

    Fischell, Erin M; Schmidt, Henrik

    2015-12-01

    One of the long term goals of autonomous underwater vehicle (AUV) minehunting is to have multiple inexpensive AUVs in a harbor autonomously classify hazards. Existing acoustic methods for target classification using AUV-based sensing, such as sidescan and synthetic aperture sonar, require an expensive payload on each outfitted vehicle and post-processing and/or image interpretation. A vehicle payload and machine learning classification methodology using bistatic angle dependence of target scattering amplitudes between a fixed acoustic source and target has been developed for onboard, fully autonomous classification with lower cost-per-vehicle. To achieve the high-quality, densely sampled three-dimensional (3D) bistatic scattering data required by this research, vehicle sampling behaviors and an acoustic payload for precision timed data acquisition with a 16 element nose array were demonstrated. 3D bistatic scattered field data were collected by an AUV around spherical and cylindrical targets insonified by a 7-9 kHz fixed source. The collected data were compared to simulated scattering models. Classification and confidence estimation were shown for the sphere versus cylinder case on the resulting real and simulated bistatic amplitude data. The final models were used for classification of simulated targets in real time in the LAMSS MOOS-IvP simulation package [M. Benjamin, H. Schmidt, P. Newman, and J. Leonard, J. Field Rob. 27, 834-875 (2010)].

  16. Stone Aerospace Testing of an Autonomous Underwater Vehicle

    NASA Image and Video Library

    2008-06-21

    View of the Autonomous Underwater Vehicle (AUV) known as Endurance designed by Stone Aerospace being lowered into the Neutral Buoyancy Laboratory (NBL) pool at the Sonny Carter Training Facility (SCTF) for testing. The AUV is being tested for potential exploration of Jupiter's moon Europa. This image was featured in the August 2008 JSC Roundup, Volume 47, Number 8.

  17. Advanced Concepts for Underwater Acoustic Channel Modeling

    NASA Astrophysics Data System (ADS)

    Etter, P. C.; Haas, C. H.; Ramani, D. V.

    2014-12-01

    This paper examines nearshore underwater-acoustic channel modeling concepts and compares channel-state information requirements against existing modeling capabilities. This process defines a subset of candidate acoustic models suitable for simulating signal propagation in underwater communications. Underwater-acoustic communications find many practical applications in coastal oceanography, and networking is the enabling technology for these applications. Such networks can be formed by establishing two-way acoustic links between autonomous underwater vehicles and moored oceanographic sensors. These networks can be connected to a surface unit for further data transfer to ships, satellites, or shore stations via a radio-frequency link. This configuration establishes an interactive environment in which researchers can extract real-time data from multiple, but distant, underwater instruments. After evaluating the obtained data, control messages can be sent back to individual instruments to adapt the networks to changing situations. Underwater networks can also be used to increase the operating ranges of autonomous underwater vehicles by hopping the control and data messages through networks that cover large areas. A model of the ocean medium between acoustic sources and receivers is called a channel model. In an oceanic channel, characteristics of the acoustic signals change as they travel from transmitters to receivers. These characteristics depend upon the acoustic frequency, the distances between sources and receivers, the paths followed by the signals, and the prevailing ocean environment in the vicinity of the paths. Properties of the received signals can be derived from those of the transmitted signals using these channel models. This study concludes that ray-theory models are best suited to the simulation of acoustic signal propagation in oceanic channels and identifies 33 such models that are eligible candidates.

  18. Visual inspection of sea bottom structures by an autonomous underwater vehicle.

    PubMed

    Foresti, G L

    2001-01-01

    This paper describes a vision-based system for inspections of underwater structures, e.g., pipelines, cables, etc., by an autonomous underwater vehicle (AUV). Usually underwater inspections are performed by remote operated vehicles (ROVs) driven by human operators placed in a support vessel. However, this task is often challenging, especially in conditions of poor visibility or in presence of strong currents. The system proposed allows the AUV to accomplish the task in autonomy. Moreover, the use of a three-dimensional (3-D) model of the environment and of an extended Kalman filter (EKF) allows the guidance and the control of the vehicle in real time. Experiments done on real underwater images have demonstrated the validity of the proposed method and its efficiency in the case of critical and complex situations.

  19. Cooperative Localization for Autonomous Underwater Vehicles

    DTIC Science & Technology

    2009-02-01

    Robotics and Automation, 18(5):781–795, Oct 2002. [74] S. I. Roumeliotis and I. Rekleitis . Analysis of multirobot localization uncertainty propagation... Rekleitis . Propagation of uncertainty in cooperative multirobot localization: Analysis and experimental results. Autonomous Robots, 17(1):1573–7527, July

  20. Boxfishes as unusually well-controlled autonomous underwater vehicles.

    PubMed

    Gordon, M S; Hove, J R; Webb, P W; Weihs, D

    2000-01-01

    Boxfishes (family Ostraciidae) are tropical reef-dwelling marine bony fishes that have about three-fourths of their body length encased in a rigid bony test. As a result, almost all of their swimming movements derive from complex combinations of movements of their median and paired fins (MPF locomotion). In terms of both body design and swimming performance, they are among the most sophisticated examples known of naturally evolved vertebrate autonomous underwater vehicles. Quantitative studies of swimming performance, biomechanics, and energetics in one model species have shown that (i) they are surprisingly strong, fast swimmers with great endurance; (ii) classical descriptions of how they swim were incomplete: they swim at different speeds using three different gaits; (iii) they are unusually dynamically well controlled and stable during sustained and prolonged rectilinear swimming; and (iv) despite unusually high parasite (fuselage) drag, they show energetic costs of transport indistinguishable from those of much better streamlined fishes using body and caudal fin (BCF) swimming modes at similar water temperatures and over comparable ranges of swimming speeds. We summarize an analysis of these properties based on a dynamic model of swimming in these fishes. This model accounts for their control, stability, and efficiency in moving through the water at moderate speeds in terms of gait changes, of water-flow patterns over body surfaces, and of complex interactions of thrust vectors generated by fin movements.

  1. Terrain aided navigation for autonomous underwater vehicles with coarse maps

    NASA Astrophysics Data System (ADS)

    Zhou, Ling; Cheng, Xianghong; Zhu, Yixian

    2016-09-01

    Terrain aided navigation (TAN) is a form of geophysical localization technique for autonomous underwater vehicles (AUVs) operating in GPS-denied environments. TAN performance on sensor-rich AUVs has been evaluated in sea trials. However, many challenges remain before TAN can be successfully implemented on sensor-limited AUVs, especially with coarse maps. To improve TAN performance over coarse maps, a Gaussian process (GP) is proposed for the modeling of bathymetric terrain and integrated into the particle filter (GP-PF). GP is applied to provide not only the bathymetric value prediction through learning a set of bathymetric data from coarse maps but also the variance of the prediction. As a measurement update, calculated on bathymetric deviation is performed through the PF to obtain absolute and bounded positioning accuracy. Through the analysis of TAN performance on experimental data for two different terrains with map resolutions of 10-50 m, both the ability of the proposed model to represent the actual bathymetric terrain with accuracy and the effect of the GP-PF for TAN on sensor-limited systems in suited terrain are demonstrated. The experiment results further verify that there is an inverse relationship between the coarseness of the map and the overall TAN accuracy in rough terrains, but there is hardly any relationship between them in relatively flat terrains.

  2. Obstacle Avoidance And Navigational Sensing For An Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Chande, A. M.; Noon, K. M.

    1987-02-01

    This paper addresses the critical issues of sense acquisition and sense analysis, using multiple Obstacle Avoidance (OA) sensors, for Autonomous Underwater Vehicles (AUVs). Currently, an AUV research and development testbed is being engineered at Martin Marietta Baltimore Aerospace, and the pertinent research on OA sensing that may be applied to such a testbed is presented. The complexities of relevant and conventional navigation systems for undersea vehicles are also discussed. Using a multitude of sensors and the Zonal-Spot Environmental Analysis (ZSEA) sensing technique, the spatial scenarios are characterized cogently by amalgamating the sensor information to form a description of the external world, which in turn are preserved in a world model database. The ZSEA sensing strategy performs sensor-level processes to recognize obstacles with certain levels of surety, based on apriori semantic data, and thereby provides safer and more efficient path planning capabilities to the AUV. Furthermore, the ZSEA sensing strategy ameliorates sensory deprivation and paves the way for the incremental enhancement of the control process at the higher levels without having to modify the lower servocontrol levels.

  3. A mission executor for an autonomous underwater vehicle

    NASA Technical Reports Server (NTRS)

    Lee, Yuh-Jeng; Wilkinson, Paul

    1991-01-01

    The Naval Postgraduate School has been conducting research into the design and testing of an Autonomous Underwater Vehicle (AUV). One facet of this research is to incrementally design a software architecture and implement it in an advanced testbed, the AUV II. As part of the high level architecture, a Mission Executor is being constructed using CLIPS (C Language Integrated Production System) version 5.0. The Mission Executor is an expert system designed to oversee progress from the AUV launch point to a goal area and back to the origin. It is expected that the executor will make informed decisions about the mission, taking into account the navigational path, the vehicle subsystem health, and the sea environment, as well as the specific mission profile which is downloaded from an offboard mission planner. Heuristics for maneuvering, avoidance of uncharted obstacles, waypoint navigation, and reaction to emergencies (essentially the expert knowledge of a submarine captain) are required. Many of the vehicle subsystems are modeled as objects using the CLIPS Object Oriented Language (COOL) embedded in CLIPS 5.0. Also, truth maintenance is applied to the knowledge base to keep configurations updated.

  4. Risk analysis for autonomous underwater vehicle operations in extreme environments.

    PubMed

    Brito, Mario Paulo; Griffiths, Gwyn; Challenor, Peter

    2010-12-01

    Autonomous underwater vehicles (AUVs) are used increasingly to explore hazardous marine environments. Risk assessment for such complex systems is based on subjective judgment and expert knowledge as much as on hard statistics. Here, we describe the use of a risk management process tailored to AUV operations, the implementation of which requires the elicitation of expert judgment. We conducted a formal judgment elicitation process where eight world experts in AUV design and operation were asked to assign a probability of AUV loss given the emergence of each fault or incident from the vehicle's life history of 63 faults and incidents. After discussing methods of aggregation and analysis, we show how the aggregated risk estimates obtained from the expert judgments were used to create a risk model. To estimate AUV survival with mission distance, we adopted a statistical survival function based on the nonparametric Kaplan-Meier estimator. We present theoretical formulations for the estimator, its variance, and confidence limits. We also present a numerical example where the approach is applied to estimate the probability that the Autosub3 AUV would survive a set of missions under Pine Island Glacier, Antarctica in January-March 2009.

  5. Ocean outfall plume characterization using an Autonomous Underwater Vehicle.

    PubMed

    Rogowski, Peter; Terrill, Eric; Otero, Mark; Hazard, Lisa; Middleton, William

    2013-01-01

    A monitoring mission to map and characterize the Point Loma Ocean Outfall (PLOO) wastewater plume using an Autonomous Underwater Vehicle (AUV) was performed on 3 March 2011. The mobility of an AUV provides a significant advantage in surveying discharge plumes over traditional cast-based methods, and when combined with optical and oceanographic sensors, provides a capability for both detecting plumes and assessing their mixing in the near and far-fields. Unique to this study is the measurement of Colored Dissolved Organic Matter (CDOM) in the discharge plume and its application for quantitative estimates of the plume's dilution. AUV mission planning methodologies for discharge plume sampling, plume characterization using onboard optical sensors, and comparison of observational data to model results are presented. The results suggest that even under variable oceanic conditions, properly planned missions for AUVs equipped with an optical CDOM sensor in addition to traditional oceanographic sensors, can accurately characterize and track ocean outfall plumes at higher resolutions than cast-based techniques.

  6. Bluefin autonomous underwater vehicles: Programs, systems, and acoustic issues

    NASA Astrophysics Data System (ADS)

    Bondaryk, Joseph E.

    2001-05-01

    Bluefin Robotics Corporation has been manufacturing autonomous underwater vehicles (AUVs) since spinning out of the MIT Sea Grant Laboratory in 1997. Bluefin currently makes three different diameter models of AUVs; the 9, 12, and 21, all based on the same free-flooded architecture and vectored-thrust propulsion design. Auxiliary acoustic systems include acoustic abort, ranging beacons, and acoustic modems. Vehicle navigation is aided by a downward-looking acoustic Doppler velocity logger (DVL). Sonar payloads can include: bottom profiler, side-scan sonar, SAS, forward-looking imagers (DIDSON), as well as horizontal and vertical discrete hydrophone arrays. Acoustic issues that arise include: (1) transmission of sound through the ABS plastic vehicle shell; (2) the impact of vehicle self-noise on data; (3) interoperability of sonars with other acoustic emitters present on and off the vehicle; and (4) the impact of navigation on some acoustic operations like SAS. This talk will illustrate these issues with real data collected on various Bluefin vehicles.

  7. Development of an Underwater Gravity Measurement System Using Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Shinohara, M.; Ishihara, T.; Yamada, T.; Araya, A.; Kanazawa, T.; Fujimoto, H.; Tsukioka, S.; Omika, S.; Uehira, K.; Iizasa, K.

    2015-12-01

    Gravity survey is one of powerful methods to obtain density structure in crust, especially for exploration of underground deposits. Recent technology of autonomous underwater vehicle (AUV) enables us measure gravity in underwater environment. Measurement of both gravity and gravity gradient is useful to estimate structure. From a model calculation, resolution of 0.1 mGal for gravity and 10 Etoves (E) for gradient measurement is needed for detection of seafloor deposits. From these objectives and specification, we have developed an underwater gravity measurement system for exploration below a seafloor using an AUV. For the gravimeter system, a gravimeter is mounted on a levelling mechanism to keep vertical. Depth rating of the system is 4,200 m. We confirmed that our gravity measurement system has an accuracy of less than 0.04 mGal on a land experiment. The gradiometer has two identical gravimeter aligned vertically 44 cm apart. Difference between two gravimeters is calculated for gravity gradient and a levelling system is also used to keep vertical. We estimate accuracy of 10 E from background noise spectra. We chose AUV Urashima belonging to JAMSTEC, because stable navigation is possible. All the power is supplied from the Urashima and acoustic communication system enables real-time monitoring of the system. The first observation was carried out in September 2012 in Sagami-Bay, Japan. The Urashima made round trip along a single profile. We succeeded in obtaining gravity data and other data for compensation. Information to measure gravity gradient is also obtained. After the data processing, our gravity system is estimated to have accuracy of 0.1 mGal. In August 2014, we carried out the second gravity survey using our system in Izena caldera, the middle Okinawa Trough, where seafloor deposits had been found. The Urashima was navigated on 15 profiles in the survey area at constant speed and depth. We obtained the data from both the gravimeter and gradiometer with

  8. A Mission Planning Expert System with Three-Dimensional Path Optimization for the NPS Model 2 Autonomous Underwater Vehicle

    DTIC Science & Technology

    1990-06-01

    taken in each phase. The task of transforming the high-level mission specifications to low-level plans is presently done by the human mission planner...while others minimize the time required for planning. However, since it is inappropriate for the human planner to be thoroughly familiar with the...vehicle to operate autonomously without human intervention in its fulfillment of a given mission. This can only be achieved if the vehicles are endowed

  9. Synthesis of a PID-controller of a trim robust control system of an autonomous underwater vehicle

    NASA Astrophysics Data System (ADS)

    Khozhaev, I. V.; Gayvoronskiy, S. A.

    2016-04-01

    Autonomous underwater vehicles are often used for performing scientific, emergency or other types of missions under harsh conditions and environments, which can have non-stable, variable parameters. So, the problem of developing autonomous underwater vehicle motion control systems, capable of operating properly in random environments, is highly relevant. The paper is dedicated to the synthesis of a PID-controller of a trim robust control system, capable of keeping an underwater vehicle stable during a translation at different angles of attack. In order to synthesize the PID-controller, two problems were solved: a new method of synthesizing a robust controller was developed and a mathematical model of an underwater vehicle motion process was derived. The newly developed mathematical model structure is simpler than others due to acceptance of some of the system parameters as interval ones. The synthesis method is based on a system poles allocation approach and allows providing the necessary transient process quality in a considered system.

  10. Large Scale Structure From Motion for Autonomous Underwater Vehicle Surveys

    DTIC Science & Technology

    2004-09-01

    from Figure 6-9 that most of the outliers correspond to the broad carpet waves . 6.3 Results: Bermuda survey 6.3.1 Context In August 2002 the SeaBED...moves, power and/or size limitations lead to lighting patterns that are far from uniform (Figure 1-1). Also with the advent of autonomous underwater...with strobed light sources rather than continuous lighting, and acquire low overlap imagery in order to preserve power and cover greater distances

  11. Hydro-Piezoelectricity: A Renewable Energy Source for Autonomous Underwater Vehicles

    DTIC Science & Technology

    1999-09-30

    Hydro-Piezoelectricity: A Renewable Energy Source For Autonomous Underwater Vehicles Dr. George W. Taylor Ocean Power Technologies, Inc. 1590 Reed...00-00-1999 4. TITLE AND SUBTITLE Hydro-Piezoelectricity: A Renewable Energy Source For Autonomous Underwater Vehicles 5a. CONTRACT NUMBER 5b

  12. Sonar Localization of an Autonomous Underwater Vehicle

    DTIC Science & Technology

    1993-12-01

    version number, for example, SIMUL8 .M. SIMUL5.M is the main source code, which initializes the filter parameters, the simulated vehicle state, the Extended...FOR PLANAR MOTION OF THE AUV ....... .11 F. SIMULATION RESULTS .......................... 15 Ill. POTENTIAL FUNCTION APPROACH FOR ENVIRONMENT...21 A. GENERAL ................................... 21 B. MODELLING ASSUMPTIONS ...................... 21 C. SIMULATION RESULTS

  13. Controlling autonomous underwater floating platforms using bacterial fermentation.

    PubMed

    Biffinger, Justin C; Fitzgerald, Lisa A; Howard, Erinn C; Petersen, Emily R; Fulmer, Preston A; Wu, Peter K; Ringeisen, Bradley R

    2013-01-01

    Biogenic gas has a wide range of energy applications from being used as a source for crude bio-oil components to direct ignition for heating. The current study describes the use of biogenic gases from Clostridium acetobutylicum for a new application-renewable ballast regeneration for autonomous underwater devices. Uninterrupted (continuous) and blocked flow (pressurization) experiments were performed to determine the overall biogas composition and total volume generated from a semirigid gelatinous matrix. For stopped flow experiments, C. acetobutylicum generated a maximum pressure of 55 psi over 48 h composed of 60 % hydrogen gas when inoculated in a 5 % agar (w/v) support with 5 % glucose (w/v) in the matrix. Typical pressures over 24 h at 318 K ranged from 10 to 33 psi. These blocked flow experiments show for the first time the use of microbial gas production as a way to repressurize gas cylinders. Continuous flow experiments successfully demonstrated how to deliver biogas to an open ballast control configuration for deployable underwater platforms. This study is a starting point for engineering and microbiology investigations of biogas which will advance the integration of biology within autonomous systems.

  14. Optical Delineation of Benthic Habitat Using an Autonomous Underwater Vehicle

    SciTech Connect

    Moline, Mark A.; Woodruff, Dana L.; Evans, Nathan R.

    2007-06-01

    To improve understanding and characterization of coastal regions, there has been an increasing emphasis on autonomous systems that can sample the ocean on relevant scales. Autonomous underwater vehicles (AUVs) with active propulsion are especially well suited for studies of the coastal ocean because they are able to provide systematic and near-synoptic spatial observations. With this capability, science users are beginning to integrate sensor suits for a broad range of specific and often novel applications. Here, the relatively mature Remote Environmental Monitoring Units (REMUS) AUV system is configured with multi-spectral radiometers to delineate benthic habitat in Sequim Bay, WA. The vehicle was deployed in a grid pattern along 5 km of coastline in depths from 30 to less than 2 meters. Similar to satellite and/or aerial remote sensing, the bandwidth ratios from the downward looking radiance sensor and upward looking irradiance sensor were used to identify beds of eelgrass on sub-meter scales. Strong correlations were found between the optical reflectance signals and the geo-referenced in situ data collected with underwater video within the grid. Results demonstrate the ability of AUVs to map littoral habitats at high resolution and highlight the overall utility of the REMUS vehicle for nearshore oceanography.

  15. Reactor Power for Large Displacement Autonomous Underwater Vehicles

    SciTech Connect

    McClure, Patrick Ray; Reid, Robert Stowers; Poston, David Irvin; Dasari, Venkateswara Rao

    2016-08-24

    This is a PentaChart on reactor power for large displacement autonomous underwater vehicles. Currently AUVs use batteries or combinations of batteries and fuel cells for power. Battery/fuel cell technology is limited by duration. Batteries and cell fuels are a good match for some missions, but other missions could benefit greatly by a longer duration. The goal is the following: to design nuclear systems to power an AUV and meet design constraints including non-proliferation issues, power level, size constraints, and power conversion limitations. The action plan is to continue development of a range of systems for terrestrial systems and focus on a system for Titan Moon as alternative to Pu-238 for NASA.

  16. Online Detection of Mixed Layer Depth for Autonomous Underwater Vehicles

    NASA Astrophysics Data System (ADS)

    Chu, S.; Estlin, T.; Castano, R.; Woodward, G.; Gierach, M. M.; Thompson, A. F.; Schaffer, S.

    2015-12-01

    The accurate determination of the mixed layer depth (MLD) plays a crucial role in studying ocean dynamics and climate change. Various methods to estimate MLD have been proposed [1, 2]. However there is no current consensus on the best model, which leads to large uncertainty in the estimation. The variability, coupled with the complexity of physical, chemical and biological processes involved and the uncertainty and instabilities of the upper ocean surface, makes estimating MLD a challenging task. MLD varies significantly, even across a small spatial area (< 10km), and this depth is fluctuating, even over a short period of time (< 24 hrs), depending on the season. This abstract describes our proposed online algorithm for detecting mixed layer depth that would operate onboard an autonomous underwater vehicle (AUV). Using an online method permits a more adaptive approach to estimating MLD. Our proposed algorithm is based on an ensemble approach, which includes data mining techniques for real-time peak and change detection, learned seasonal variability profile, combined with MLD estimation criteria in [1]. In this study, we analyze measurements using glider data collected from the OSMOSIS (Ocean Surface Mixing, Ocean Submesoscale Interaction Study) project, concatenated into a year-long time series [3]. The glider data consists of nine full-depth moorings, which were deployed in a 15 km by 15 km box at the Porcupine Abyssal Plain in the northeast Atlantic, centered at 16.2°W, 48.7°N. Our algorithm utilizes direct measurements of salinity, temperature, depth and time and the design is based on the spatial and temporal variability of MLD learned. We will present our initial work on tracking the MLD based on real-time simulations using the OSMOSIS glider data and discussed for the case of deploying on a single AUV. Using an online algorithm for estimating MLD in-situ enables the system to rapidly adapt to the variability in a real-world environment and also allows for

  17. Autonomous Planning and Replanning for Mine-Sweeping Unmanned Underwater Vehicles

    NASA Technical Reports Server (NTRS)

    Gaines, Daniel M.

    2010-01-01

    This software generates high-quality plans for carrying out mine-sweeping activities under resource constraints. The autonomous planning and replanning system for unmanned underwater vehicles (UUVs) takes as input a set of prioritized mine-sweep regions, and a specification of available UUV resources including available battery energy, data storage, and time available for accomplishing the mission. Mine-sweep areas vary in location, size of area to be swept, and importance of the region. The planner also works with a model of the UUV, as well as a model of the power consumption of the vehicle when idle and when moving.

  18. An Autonomous Underwater Recorder Based on a Single Board Computer.

    PubMed

    Caldas-Morgan, Manuel; Alvarez-Rosario, Alexander; Rodrigues Padovese, Linilson

    2015-01-01

    As industrial activities continue to grow on the Brazilian coast, underwater sound measurements are becoming of great scientific importance as they are essential to evaluate the impact of these activities on local ecosystems. In this context, the use of commercial underwater recorders is not always the most feasible alternative, due to their high cost and lack of flexibility. Design and construction of more affordable alternatives from scratch can become complex because it requires profound knowledge in areas such as electronics and low-level programming. With the aim of providing a solution; a well succeeded model of a highly flexible, low-cost alternative to commercial recorders was built based on a Raspberry Pi single board computer. A properly working prototype was assembled and it demonstrated adequate performance levels in all tested situations. The prototype was equipped with a power management module which was thoroughly evaluated. It is estimated that it will allow for great battery savings on long-term scheduled recordings. The underwater recording device was successfully deployed at selected locations along the Brazilian coast, where it adequately recorded animal and manmade acoustic events, among others. Although power consumption may not be as efficient as that of commercial and/or micro-processed solutions, the advantage offered by the proposed device is its high customizability, lower development time and inherently, its cost.

  19. An Autonomous Underwater Recorder Based on a Single Board Computer

    PubMed Central

    Caldas-Morgan, Manuel; Alvarez-Rosario, Alexander; Rodrigues Padovese, Linilson

    2015-01-01

    As industrial activities continue to grow on the Brazilian coast, underwater sound measurements are becoming of great scientific importance as they are essential to evaluate the impact of these activities on local ecosystems. In this context, the use of commercial underwater recorders is not always the most feasible alternative, due to their high cost and lack of flexibility. Design and construction of more affordable alternatives from scratch can become complex because it requires profound knowledge in areas such as electronics and low-level programming. With the aim of providing a solution; a well succeeded model of a highly flexible, low-cost alternative to commercial recorders was built based on a Raspberry Pi single board computer. A properly working prototype was assembled and it demonstrated adequate performance levels in all tested situations. The prototype was equipped with a power management module which was thoroughly evaluated. It is estimated that it will allow for great battery savings on long-term scheduled recordings. The underwater recording device was successfully deployed at selected locations along the Brazilian coast, where it adequately recorded animal and manmade acoustic events, among others. Although power consumption may not be as efficient as that of commercial and/or micro-processed solutions, the advantage offered by the proposed device is its high customizability, lower development time and inherently, its cost. PMID:26076479

  20. Assessment of Deep Water Archaeological Sites with Autonomous Underwater Vehicles

    NASA Astrophysics Data System (ADS)

    Foley, B. P.; Ferrini, V. L.; Bingham, B. S.; Camilli, R.; Delaporta, K.; Kourkoumelis, D.

    2006-12-01

    Deep submergence vehicle technology has recently enabled significant advances in the rapid assessment of marine archaeological sites. Precisely navigated vehicles equipped with high resolution digital cameras and high-frequency multibeam sonar systems can be used to assess not only the distribution of wreckage, but to quantify the size, distribution, and condition of individual artifacts contained within the wreck. This information is critical to deriving new knowledge of ancient civilizations based on shipwreck sites. The Woods Hole Oceanographic Institution in collaboration with the Hellenic Ministry of Culture and the Hellenic Centre for Marine Research is conducting an ongoing program to document ancient shipwrecks and refine underwater archaeological survey methods. The first project took place in 2005 near the Aegean island, Chios, when the team deployed an Autonomous Underwater Vehicle to investigate a 4th century BC wreck in 70 m water depth. Multiple low speed (20 cm/sec) digital imaging and acoustic mapping surveys were conducted at an altitude of 2.5 m yielded 200+% coverage of the wreck. Multibeam data provide centimeter resolution of the site's bathymetry, and a subset of 6000+ overlapping digital images were used to generate a continuous photomosaic of the entire wreck at sub-centimeter resolution. The full survey of the 20 m x 7 m wreck took approximately 18 hours. The second season in 2006 resulted in the survey of a historic period warship. The combination of digital imagery and sonar data reveal information about these wrecks that would otherwise be difficult to quantify. For instance, the orientation, location, number, and preservation state of amphora cargo elements observed in high-resolution imagery can be used to determine the vessel's origin and order of lading. Additionally, first-order archaeological questions can be answered: age of the wreck, cultural origin of the vessel, dimensions of the site, computation of three-dimensional cargo

  1. Autonomous Navigation for Autonomous Underwater Vehicles Based on Information Filters and Active Sensing

    PubMed Central

    He, Bo; Zhang, Hongjin; Li, Chao; Zhang, Shujing; Liang, Yan; Yan, Tianhong

    2011-01-01

    This paper addresses an autonomous navigation method for the autonomous underwater vehicle (AUV) C-Ranger applying information-filter-based simultaneous localization and mapping (SLAM), and its sea trial experiments in Tuandao Bay (Shangdong Province, P.R. China). Weak links in the information matrix in an extended information filter (EIF) can be pruned to achieve an efficient approach-sparse EIF algorithm (SEIF-SLAM). All the basic update formulae can be implemented in constant time irrespective of the size of the map; hence the computational complexity is significantly reduced. The mechanical scanning imaging sonar is chosen as the active sensing device for the underwater vehicle, and a compensation method based on feedback of the AUV pose is presented to overcome distortion of the acoustic images due to the vehicle motion. In order to verify the feasibility of the navigation methods proposed for the C-Ranger, a sea trial was conducted in Tuandao Bay. Experimental results and analysis show that the proposed navigation approach based on SEIF-SLAM improves the accuracy of the navigation compared with conventional method; moreover the algorithm has a low computational cost when compared with EKF-SLAM. PMID:22346682

  2. Autonomous navigation for autonomous underwater vehicles based on information filters and active sensing.

    PubMed

    He, Bo; Zhang, Hongjin; Li, Chao; Zhang, Shujing; Liang, Yan; Yan, Tianhong

    2011-01-01

    This paper addresses an autonomous navigation method for the autonomous underwater vehicle (AUV) C-Ranger applying information-filter-based simultaneous localization and mapping (SLAM), and its sea trial experiments in Tuandao Bay (Shangdong Province, P.R. China). Weak links in the information matrix in an extended information filter (EIF) can be pruned to achieve an efficient approach-sparse EIF algorithm (SEIF-SLAM). All the basic update formulae can be implemented in constant time irrespective of the size of the map; hence the computational complexity is significantly reduced. The mechanical scanning imaging sonar is chosen as the active sensing device for the underwater vehicle, and a compensation method based on feedback of the AUV pose is presented to overcome distortion of the acoustic images due to the vehicle motion. In order to verify the feasibility of the navigation methods proposed for the C-Ranger, a sea trial was conducted in Tuandao Bay. Experimental results and analysis show that the proposed navigation approach based on SEIF-SLAM improves the accuracy of the navigation compared with conventional method; moreover the algorithm has a low computational cost when compared with EKF-SLAM.

  3. Exploiting autonomous underwater vehicle mobility for enhanced sonar performance

    NASA Astrophysics Data System (ADS)

    Edwards, Joseph R.; Schmidt, Henrik

    2004-05-01

    Autonomous underwater vehicles (AUVs) provide a mobile sonar platform for local environmental characterization and mine hunting missions in areas that are prohibitively dangerous or otherwise inaccessible to manned vessels. Such missions are typically implemented by providing the vehicle with a series of way-points that uniformly sample the region of interest. While these preplanned sampling paths can be effective for many purposes, a higher degree of efficiency and efficacy can be achieved when the AUV is able to react to its perceived environment. Such response to the sensory stimulus represents a preliminary step toward the AUV achieving tasks in the way that a dolphin or human might. Upon sensing an object or feature of interest, the AUV can further interrogate the object by obtaining multiple views from preferred vantage points. Probabilities of detection and correct classification can be greatly impacted by a wise choice of sonar-adaptive AUV behavior. In this paper, the ability of the AUV to improve sonar performance through sonar-adaptive mission planning is investigated in the context of the mine hunting problem. Trade-offs are discussed for continuous versus scripted mission adaptations, single-minded versus multiple-objective mission control, and task-wise versus mission-wise behavior. [Work supported by ONR and SACLANTCEN.

  4. Autonomous underwater vehicle adaptive path planning for target classification

    NASA Astrophysics Data System (ADS)

    Edwards, Joseph R.; Schmidt, Henrik

    2002-11-01

    Autonomous underwater vehicles (AUVs) are being rapidly developed to carry sensors into the sea in ways that have previously not been possible. The full use of the vehicles, however, is still not near realization due to lack of the true vehicle autonomy that is promised in the label (AUV). AUVs today primarily attempt to follow as closely as possible a preplanned trajectory. The key to increasing the autonomy of the AUV is to provide the vehicle with a means to make decisions based on its sensor receptions. The current work examines the use of active sonar returns from mine-like objects (MLOs) as a basis for sensor-based adaptive path planning, where the path planning objective is to discriminate between real mines and rocks. Once a target is detected in the mine hunting phase, the mine classification phase is initialized with a derivative cost function to emphasize signal differences and enhance classification capability. The AUV moves adaptively to minimize the cost function. The algorithm is verified using at-sea data derived from the joint MIT/SACLANTCEN GOATS experiments and advanced acoustic simulation using SEALAB. The mission oriented operating system (MOOS) real-time simulator is then used to test the onboard implementation of the algorithm.

  5. Sewage outfall plume dispersion observations with an autonomous underwater vehicle.

    PubMed

    Ramos, P; Cunha, S R; Neves, M V; Pereira, F L; Quintaneiro, I

    2005-01-01

    This work represents one of the first successful applications of Autonomous Underwater Vehicles (AUVs) for interdisciplinary coastal research. A monitoring mission to study the shape and estimate the initial dilution of the S. Jacinto sewage outfall plume using an AUV was performed on July 2002. An efficient sampling strategy enabling greater improvements in spatial and temporal range of detection demonstrated that the sewage effluent plume can be clearly traced using naturally occurring tracers in the wastewater. The outfall plume was found at the surface highly influenced by the weak stratification and low currents. Dilution varying with distance downstream was estimated from the plume rise over the outfall diffuser until a nearly constant value of 130:1, 60 m from the diffuser, indicating the near field end. Our results demonstrate that AUVs can provide high-quality measurements of physical properties of effluent plumes in a very effective manner and valuable considerations about the initial mixing processes under real oceanic conditions can be further investigated.

  6. Exploring Ice-Covered Waters with an Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Hamilton, A.; Forrest, A.; Laval, B.

    2009-12-01

    Reductions in lake- and sea-ice extent and ice-shelf collapse in both the Arctic and Antarctic are exposing underlying waters to significant increases in light and heat penetration, altering water mass properties and current dynamics. These physical changes likely drive rapid biological evolution and succession in associated marine ecosystems, influencing the biogeochemical transformation of matter and energy in previously ice-covered waters. However the unaltered, or pristine state of waters covered by thick (>3m) or moving ice is poorly understood, as these environments are largely inaccessible to investigation from the surface. Advancement of autonomous underwater vehicle (AUV) technology now allows these vehicles to be utilized as platforms for polar oceanographic research, permitting exploration of previously uncharted ice-covered waters. UBC-Gavia, a 2.5 m long AUV operated out of the University of British Columbia, has been involved in several under-ice (both lake and sea) missions making it one of the few such vehicles to be successfully deployed under-ice. Results of three under-ice case studies are presented in this work: Pavilion Lake, Canada - an ice-covered temperate lake; Lake Thingvallavatn, Iceland - a subarctic lake experiencing spring ice break-up; and Joliffe Bay, Lincoln Sea, Canadian High Arctic - a near shore multi- and first-year sea ice environment. The focus of each of these case studies was to examine physical processes in the water column under ice (e.g. radiatively driven convection) using a Conductivity-Temperature-Depth (CTD) profiler mounted on the front of the vehicle. In addition, various engineering lessons were acquired in order to adapt the vehicle for deployment, operation and recovery in ice-covered waters. The next phase of research will also be presented; a planned deployment of UBC-Gavia near the McMurdo Ice Shelf in Antarctica, to map under ice structure, ice thickness and convective processes in the water column. These

  7. Autonomous Underwater Vehicle Data Management and Metadata Interoperability for Coastal Ocean Studies

    NASA Astrophysics Data System (ADS)

    McCann, M. P.; Ryan, J. P.; Chavez, F. P.; Rienecker, E.

    2004-12-01

    Data from over 1000 km of Autonomous Underwater Vehicle (AUV) surveys of Monterey Bay have been collected and cataloged in an ocean observatory data management system. The Monterey Bay Aquarium Institute's AUV is equipped with a suite of instruments that include a conductivity, temperature, depth (CTD) instrument, transmissometers, a fluorometer, a nitrate sensor, and an inertial navigation system. Data are logged on the vehicle and upon completion of a survey XML descriptions of the data are submitted to the Shore Side Data System (SSDS). Instrument data are then processed on shore to apply calibrations and produce scientifically useful data products. The SSDS employs a data model that tracks data from the instrument that created it through all the consuming processes that generate derived products. SSDS employs OPeNDAP and netCDF to provide data set interoperability at the data level. The core of SSDS is the metadata that is the catalog of these data sets and their relation to all other relevant data. The metadata is managed in a relational database and governed by a Enterprise Java Bean (EJB) server application. Cross-platform Java applications have been written to manage and visualize these data. A Java Swing application - the Hierarchical Ocean Observatory Visualization and Editing System (HOOVES) - has been developed to provide visualization of data set pedigree and data set variables. Because the SSDS data model is generalized according to "Data Producers" and "Data Containers" many different types of data can be represented in SSDS allowing for interoperability at a metadata level. Comparisons of appropriate data sets, whether they are from an autonomous underwater vehicle or from a fixed mooring are easily made using SSDS. The authors will present the SSDS data model and show examples of how the model helps organize data set metadata allowing for data discovery and interoperability. With improved discovery and interoperability the system is helping us

  8. Autonomous Underwater Vehicle Control Coordination Using a Tri-Level Hybrid Software Architecture

    DTIC Science & Technology

    1996-01-01

    Tri-Level Hybrid Software Architecture A. J. Healey1, D. B. Marco, R. B. McGhee Autonomous Underwater Vehicle Laboratory Naval Postgraduate School...the software architecture to implement them is often composed of three levels for ease of segregation and development of functionality. An...the development of coastal environmental understanding, new technology is being aimed at using (semi)autonomous vehicles, requiring acoustic

  9. Underwater Optical Wireless Channel Modeling Using Monte-Carlo Method

    NASA Astrophysics Data System (ADS)

    Saini, P. Sri; Prince, Shanthi

    2011-10-01

    At present, there is a lot of interest in the functioning of the marine environment. Unmanned or Autonomous Underwater Vehicles (UUVs or AUVs) are used in the exploration of the underwater resources, pollution monitoring, disaster prevention etc. Underwater, where radio waves do not propagate, acoustic communication is being used. But, underwater communication is moving towards Optical Communication which has higher bandwidth when compared to Acoustic Communication but has shorter range comparatively. Underwater Optical Wireless Communication (OWC) is mainly affected by the absorption and scattering of the optical signal. In coastal waters, both inherent and apparent optical properties (IOPs and AOPs) are influenced by a wide array of physical, biological and chemical processes leading to optical variability. The scattering effect has two effects: the attenuation of the signal and the Inter-Symbol Interference (ISI) of the signal. However, the Inter-Symbol Interference is ignored in the present paper. Therefore, in order to have an efficient underwater OWC link it is necessary to model the channel efficiently. In this paper, the underwater optical channel is modeled using Monte-Carlo method. The Monte Carlo approach provides the most general and most flexible technique for numerically solving the equations of Radiative transfer. The attenuation co-efficient of the light signal is studied as a function of the absorption (a) and scattering (b) coefficients. It has been observed that for pure sea water and for less chlorophyll conditions blue wavelength is less absorbed whereas for chlorophyll rich environment red wavelength signal is absorbed less comparative to blue and green wavelength.

  10. Calibration and Characterization of Autonomous Recorders Used in the Measurement of Underwater Noise.

    PubMed

    Hayman, Gary; Robinson, Stephen; Lepper, Paul

    2016-01-01

    The use of autonomous recorders is motivated by the need to monitor underwater noise, such as in response to the requirements of the European Union Marine Strategy Framework Directive. The performance of these systems is a crucial factor governing the quality of the measured data, providing traceability for future underwater noise-monitoring programs aimed at the protection of the marine environment from anthropogenic noise. In this paper, a discussion is presented of measurement methodologies for the key acoustic performance characteristics of the recorders, including self-noise, dynamic range, and the absolute sensitivity as a function of frequency of the hydrophone and recorder system.

  11. Autonomous Underwater Munitions and Explosives of Concern Detection System

    DTIC Science & Technology

    2015-03-01

    Underwater Vehicle (AUV) Team Lead. Dr. Trembanis was responsible for mission planning and AUV deployment. He managed his AUV Team including Val Schmidt...lead. Mr. Kloske was responsible for planning and coordination of the research vessel GH Gilbert and the seeding program. This page left...usage. Surveys are performed by using pre- planned mission information including speed, height above seafloor or depth, and lane or transect spacing

  12. Autonomous Underwater Vehicle Architecture Synthesis for Shipwreck Interior Exploration

    DTIC Science & Technology

    2015-12-01

    sub- cubes and so on until the finest resolution required is reached (Fairfield et al. 2007). Figure 16 illustrates the octree principle. 59...to these remote places. One new and rapidly developing technological field, however, offers promise. Unmanned undersea vehicles may be the key to... on unmanned underwater vehicles (UUVs) and a discussion of AUVs set the stage for an enhanced understanding of the design reference mission (DRM

  13. A Parallel Hypothesis Method of Autonomous Underwater Vehicle Navigation

    DTIC Science & Technology

    2009-06-01

    complicated terrain there is a high risk of shadowing in which the line-of-sight path between the AUV and a given transponder is blocked. An increased...existing operational paradigm also breaks down in the presence of shadowing in which a vehicle is operating in a rough underwater terrain and its line of...sight with one or more of the transponders is physically obstructed. The increased risk of shadowing in rough terrain makes it difficult to construct

  14. Secure Cooperation of Autonomous Mobile Sensors Using an Underwater Acoustic Network

    PubMed Central

    Caiti, Andrea; Calabrò, Vincenzo; Dini, Gianluca; Duca, Angelica Lo; Munafò, Andrea

    2012-01-01

    Methodologies and algorithms are presented for the secure cooperation of a team of autonomous mobile underwater sensors, connected through an acoustic communication network, within surveillance and patrolling applications. In particular, the work proposes a cooperative algorithm in which the mobile underwater sensors (installed on Autonomous Underwater Vehicles—AUVs) respond to simple local rules based on the available information to perform the mission and maintain the communication link with the network (behavioral approach). The algorithm is intrinsically robust: with loss of communication among the vehicles the coverage performance (i.e., the mission goal) is degraded but not lost. The ensuing form of graceful degradation provides also a reactive measure against Denial of Service. The cooperative algorithm relies on the fact that the available information from the other sensors, though not necessarily complete, is trustworthy. To ensure trustworthiness, a security suite has been designed, specifically oriented to the underwater scenario, and in particular with the goal of reducing the communication overhead introduced by security in terms of number and size of messages. The paper gives implementation details on the integration between the security suite and the cooperative algorithm and provides statistics on the performance of the system as collected during the UAN project sea trial held in Trondheim, Norway, in May 2011. PMID:22438748

  15. Secure cooperation of autonomous mobile sensors using an underwater acoustic network.

    PubMed

    Caiti, Andrea; Calabrò, Vincenzo; Dini, Gianluca; Lo Duca, Angelica; Munafò, Andrea

    2012-01-01

    Methodologies and algorithms are presented for the secure cooperation of a team of autonomous mobile underwater sensors, connected through an acoustic communication network, within surveillance and patrolling applications. In particular, the work proposes a cooperative algorithm in which the mobile underwater sensors (installed on Autonomous Underwater Vehicles-AUVs) respond to simple local rules based on the available information to perform the mission and maintain the communication link with the network (behavioral approach). The algorithm is intrinsically robust: with loss of communication among the vehicles the coverage performance (i.e., the mission goal) is degraded but not lost. The ensuing form of graceful degradation provides also a reactive measure against Denial of Service. The cooperative algorithm relies on the fact that the available information from the other sensors, though not necessarily complete, is trustworthy. To ensure trustworthiness, a security suite has been designed, specifically oriented to the underwater scenario, and in particular with the goal of reducing the communication overhead introduced by security in terms of number and size of messages. The paper gives implementation details on the integration between the security suite and the cooperative algorithm and provides statistics on the performance of the system as collected during the UAN project sea trial held in Trondheim, Norway, in May 2011.

  16. Parametric geometric model and shape optimization of an underwater glider with blended-wing-body

    NASA Astrophysics Data System (ADS)

    Sun, Chunya; Song, Baowei; Wang, Peng

    2015-11-01

    Underwater glider, as a new kind of autonomous underwater vehicles, has many merits such as long-range, extended-duration and low costs. The shape of underwater glider is an important factor in determining the hydrodynamic efficiency. In this paper, a high lift to drag ratio configuration, the Blended-Wing-Body (BWB), is used to design a small civilian under water glider. In the parametric geometric model of the BWB underwater glider, the planform is defined with Bezier curve and linear line, and the section is defined with symmetrical airfoil NACA 0012. Computational investigations are carried out to study the hydrodynamic performance of the glider using the commercial Computational Fluid Dynamics (CFD) code Fluent. The Kriging-based genetic algorithm, called Efficient Global Optimization (EGO), is applied to hydrodynamic design optimization. The result demonstrates that the BWB underwater glider has excellent hydrodynamic performance, and the lift to drag ratio of initial design is increased by 7% in the EGO process.

  17. Biogeography-based combinatorial strategy for efficient autonomous underwater vehicle motion planning and task-time management

    NASA Astrophysics Data System (ADS)

    Zadeh, S. M.; Powers, D. M. W.; Sammut, K.; Yazdani, A. M.

    2016-12-01

    Autonomous Underwater Vehicles (AUVs) are capable of spending long periods of time for carrying out various underwater missions and marine tasks. In this paper, a novel conflict-free motion planning framework is introduced to enhance underwater vehicle's mission performance by completing maximum number of highest priority tasks in a limited time through a large scale waypoint cluttered operating field, and ensuring safe deployment during the mission. The proposed combinatorial route-path planner model takes the advantages of the Biogeography-Based Optimization (BBO) algorithm toward satisfying objectives of both higher-lower level motion planners and guarantees maximization of the mission productivity for a single vehicle operation. The performance of the model is investigated under different scenarios including the particular cost constraints in time-varying operating fields. To show the reliability of the proposed model, performance of each motion planner assessed separately and then statistical analysis is undertaken to evaluate the total performance of the entire model. The simulation results indicate the stability of the contributed model and its feasible application for real experiments.

  18. Rule Based Control for Mission Execution for an Autonomous Underwater Vehicle

    DTIC Science & Technology

    1992-02-01

    potential ability to operate at over-the-horizon distances make autonomous underwater vehicles highly desirable for many subsea activities and operations...discussed in the following sections. reptan Mission LogI reques decisions’ mission Fig’ure 1: The Interface 3.1 Downloading Mission Profile from the...Because of the relatively limited distance of the AUV sonar, avoidance action must be taken early. An obstacle is initially checked for its potential to

  19. Advanced Non-Linear Control Algorithms Applied to Design Highly Maneuverable Autonomous Underwater Vehicles (AUVs)

    DTIC Science & Technology

    2007-08-01

    Advanced non- linear control algorithms applied to design highly maneuverable Autonomous Underwater Vehicles (AUVs) Vladimir Djapic, Jay A. Farrell...hierarchical such that an ”inner loop” non- linear controller (outputs the appropriate thrust values) is the same for all mission scenarios while a...library of ”outer-loop” non- linear controllers are available to implement specific maneuvering scenarios. On top of the outer-loop is the mission planner

  20. Aspect-dependent radiated noise analysis of an underway autonomous underwater vehicle.

    PubMed

    Gebbie, John; Siderius, Martin; Allen, John S

    2012-11-01

    This paper presents an analysis of the acoustic emissions emitted by an underway REMUS-100 autonomous underwater vehicle (AUV) that were obtained near Honolulu Harbor, HI using a fixed, bottom-mounted horizontal line array (HLA). Spectral analysis, beamforming, and cross-correlation facilitate identification of independent sources of noise originating from the AUV. Fusion of navigational records from the AUV with acoustic data from the HLA allows for an aspect-dependent presentation of calculated source levels of the strongest propulsion tone.

  1. An apparatus to estimate the hydrodynamic coefficients of autonomous underwater vehicles using water tunnel testing.

    PubMed

    Nouri, N M; Mostafapour, K; Bahadori, R

    2016-06-01

    Hydrodynamic coefficients or hydrodynamic derivatives of autonomous underwater vehicles (AUVs) play an important role in their development and maneuverability. The most popular way of estimating their coefficients is to implement captive model tests such as straight line tests and planar motion mechanism (PMM) tests in the towing tanks. This paper aims to develop an apparatus based on planar experiments of water tunnel in order to estimate hydrodynamic derivatives due to AUVs' acceleration and velocity. The capability of implementing straight line tests and PMM ones using mechanical oscillators located in the downstream flow of the model is considered in the design procedure of the system. The hydrodynamic derivatives that resulted from the acceleration and velocity of the AUV model were estimated using the apparatus that we developed. Static and dynamics test results were compared for the similar derivatives. The findings showed that the system provided the basis for conducting static tests, i.e., straight-line and dynamic tests that included pure pitch and pure heave. By conducting such tests in a water tunnel, we were able to eliminate errors related to the time limitation of the tests and the effects of surface waves in the towing tank on AUVs with applications in the deep sea.

  2. An apparatus to estimate the hydrodynamic coefficients of autonomous underwater vehicles using water tunnel testing

    NASA Astrophysics Data System (ADS)

    Nouri, N. M.; Mostafapour, K.; Bahadori, R.

    2016-06-01

    Hydrodynamic coefficients or hydrodynamic derivatives of autonomous underwater vehicles (AUVs) play an important role in their development and maneuverability. The most popular way of estimating their coefficients is to implement captive model tests such as straight line tests and planar motion mechanism (PMM) tests in the towing tanks. This paper aims to develop an apparatus based on planar experiments of water tunnel in order to estimate hydrodynamic derivatives due to AUVs' acceleration and velocity. The capability of implementing straight line tests and PMM ones using mechanical oscillators located in the downstream flow of the model is considered in the design procedure of the system. The hydrodynamic derivatives that resulted from the acceleration and velocity of the AUV model were estimated using the apparatus that we developed. Static and dynamics test results were compared for the similar derivatives. The findings showed that the system provided the basis for conducting static tests, i.e., straight-line and dynamic tests that included pure pitch and pure heave. By conducting such tests in a water tunnel, we were able to eliminate errors related to the time limitation of the tests and the effects of surface waves in the towing tank on AUVs with applications in the deep sea.

  3. Design Features of Small Brayton Cycles for Autonomous Underwater Vehicles.

    DTIC Science & Technology

    1987-06-01

    considered for small autonomous submersibles to meet long duration and high speed operations. The closed cycle Brayton engine using lithium sulfur...will be hull mounted to save space, to alleviate the need for a pump to circulate the sea water and for improved maintenance. Cooler calculations can...the analysis, aided not only recuperator design, but system design as well . Additionally, to maintain system efficiency and to provide a viable

  4. Containment control of networked autonomous underwater vehicles: A predictor-based neural DSC design.

    PubMed

    Peng, Zhouhua; Wang, Dan; Wang, Wei; Liu, Lu

    2015-11-01

    This paper investigates the containment control problem of networked autonomous underwater vehicles in the presence of model uncertainty and unknown ocean disturbances. A predictor-based neural dynamic surface control design method is presented to develop the distributed adaptive containment controllers, under which the trajectories of follower vehicles nearly converge to the dynamic convex hull spanned by multiple reference trajectories over a directed network. Prediction errors, rather than tracking errors, are used to update the neural adaptation laws, which are independent of the tracking error dynamics, resulting in two time-scales to govern the entire system. The stability property of the closed-loop network is established via Lyapunov analysis, and transient property is quantified in terms of L2 norms of the derivatives of neural weights, which are shown to be smaller than the classical neural dynamic surface control approach. Comparative studies are given to show the substantial improvements of the proposed new method. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  5. Thick and deformed Antarctic sea ice mapped with autonomous underwater vehicles

    NASA Astrophysics Data System (ADS)

    Williams, G.; Maksym, T.; Wilkinson, J.; Kunz, C.; Murphy, C.; Kimball, P.; Singh, H.

    2015-01-01

    Satellites have documented trends in Antarctic sea-ice extent and its variability for decades, but estimating sea-ice thickness in the Antarctic from remote sensing data remains challenging. In situ observations needed for validation of remote sensing data and sea-ice models are limited; most have been restricted to a few point measurements on selected ice floes, or to visual shipboard estimates. Here we present three-dimensional (3D) floe-scale maps of sea-ice draft for ten floes, compiled from two springtime expeditions by an autonomous underwater vehicle to the near-coastal regions of the Weddell, Bellingshausen, and Wilkes Land sectors of Antarctica. Mean drafts range from 1.4 to 5.5 m, with maxima up to 16 m. We also find that, on average, 76% of the ice volume is deformed ice. Our surveys indicate that the floes are much thicker and more deformed than reported by most drilling and ship-based measurements of Antarctic sea ice. We suggest that thick ice in the near-coastal and interior pack may be under-represented in existing in situ assessments of Antarctic sea ice and hence, on average, Antarctic sea ice may be thicker than previously thought.

  6. Terrain matching image pre-process and its format transform in autonomous underwater navigation

    NASA Astrophysics Data System (ADS)

    Cao, Xuejun; Zhang, Feizhou; Yang, Dongkai; Yang, Bogang

    2007-06-01

    Underwater passive navigation technology is one of the important development orientations in the field of modern navigation. With the advantage of high self-determination, stealth at sea, anti-jamming and high precision, passive navigation is completely meet with actual navigation requirements. Therefore passive navigation has become a specific navigating method for underwater vehicles. The scientists and researchers in the navigating field paid more attention to it. The underwater passive navigation can provide accurate navigation information with main Inertial Navigation System (INS) for a long period, such as location and speed. Along with the development of micro-electronics technology, the navigation of AUV is given priority to INS assisted with other navigation methods, such as terrain matching navigation. It can provide navigation ability for a long period, correct the errors of INS and make AUV not emerge from the seabed termly. With terrain matching navigation technique, in the assistance of digital charts and ocean geographical characteristics sensors, we carry through underwater image matching assistant navigation to obtain the higher location precision, therefore it is content with the requirement of underwater, long-term, high precision and all-weather of the navigation system for Autonomous Underwater Vehicles. Tertian-assistant navigation (TAN) is directly dependent on the image information (map information) in the navigating field to assist the primary navigation system according to the path appointed in advance. In TAN, a factor coordinative important with the system operation is precision and practicability of the storable images and the database which produce the image data. If the data used for characteristics are not suitable, the system navigation precision will be low. Comparing with terrain matching assistant navigation system, image matching navigation system is a kind of high precision and low cost assistant navigation system, and its

  7. Data-based depth estimation of an incoming autonomous underwater vehicle.

    PubMed

    Yang, T C; Xu, Wen

    2016-10-01

    The data-based method for estimating the depth of a moving source is demonstrated experimentally for an incoming autonomous underwater vehicle traveling toward a vertical line array (VLA) of receivers at constant speed/depth. The method assumes no information on the sound-speed and bottom profile. Performing a wavenumber analysis of a narrowband signal for each hydrophone, the energy of the (modal) spectral peaks as a function of the receiver depth is used to estimate the depth of the source, traveling within the depth span of the VLA. This paper reviews the theory, discusses practical implementation issues, and presents the data analysis results.

  8. An Early Underwater Artificial Vision Model in Ocean Investigations via Independent Component Analysis

    PubMed Central

    Nian, Rui; Liu, Fang; He, Bo

    2013-01-01

    Underwater vision is one of the dominant senses and has shown great prospects in ocean investigations. In this paper, a hierarchical Independent Component Analysis (ICA) framework has been established to explore and understand the functional roles of the higher order statistical structures towards the visual stimulus in the underwater artificial vision system. The model is inspired by characteristics such as the modality, the redundancy reduction, the sparseness and the independence in the early human vision system, which seems to respectively capture the Gabor-like basis functions, the shape contours or the complicated textures in the multiple layer implementations. The simulation results have shown good performance in the effectiveness and the consistence of the approach proposed for the underwater images collected by autonomous underwater vehicles (AUVs). PMID:23863855

  9. An early underwater artificial vision model in ocean investigations via independent component analysis.

    PubMed

    Nian, Rui; Liu, Fang; He, Bo

    2013-07-16

    Underwater vision is one of the dominant senses and has shown great prospects in ocean investigations. In this paper, a hierarchical Independent Component Analysis (ICA) framework has been established to explore and understand the functional roles of the higher order statistical structures towards the visual stimulus in the underwater artificial vision system. The model is inspired by characteristics such as the modality, the redundancy reduction, the sparseness and the independence in the early human vision system, which seems to respectively capture the Gabor-like basis functions, the shape contours or the complicated textures in the multiple layer implementations. The simulation results have shown good performance in the effectiveness and the consistence of the approach proposed for the underwater images collected by autonomous underwater vehicles (AUVs).

  10. Underwater noise modelling for environmental impact assessment

    SciTech Connect

    Farcas, Adrian; Thompson, Paul M.; Merchant, Nathan D.

    2016-02-15

    Assessment of underwater noise is increasingly required by regulators of development projects in marine and freshwater habitats, and noise pollution can be a constraining factor in the consenting process. Noise levels arising from the proposed activity are modelled and the potential impact on species of interest within the affected area is then evaluated. Although there is considerable uncertainty in the relationship between noise levels and impacts on aquatic species, the science underlying noise modelling is well understood. Nevertheless, many environmental impact assessments (EIAs) do not reflect best practice, and stakeholders and decision makers in the EIA process are often unfamiliar with the concepts and terminology that are integral to interpreting noise exposure predictions. In this paper, we review the process of underwater noise modelling and explore the factors affecting predictions of noise exposure. Finally, we illustrate the consequences of errors and uncertainties in noise modelling, and discuss future research needs to reduce uncertainty in noise assessments.

  11. A swarm of autonomous miniature underwater robot drifters for exploring submesoscale ocean dynamics.

    PubMed

    Jaffe, Jules S; Franks, Peter J S; Roberts, Paul L D; Mirza, Diba; Schurgers, Curt; Kastner, Ryan; Boch, Adrien

    2017-01-24

    Measuring the ever-changing 3-dimensional (3D) motions of the ocean requires simultaneous sampling at multiple locations. In particular, sampling the complex, nonlinear dynamics associated with submesoscales (<1-10 km) requires new technologies and approaches. Here we introduce the Mini-Autonomous Underwater Explorer (M-AUE), deployed as a swarm of 16 independent vehicles whose 3D trajectories are measured near-continuously, underwater. As the vehicles drift with the ambient flow or execute preprogrammed vertical behaviours, the simultaneous measurements at multiple, known locations resolve the details of the flow within the swarm. We describe the design, construction, control and underwater navigation of the M-AUE. A field programme in the coastal ocean using a swarm of these robots programmed with a depth-holding behaviour provides a unique test of a physical-biological interaction leading to plankton patch formation in internal waves. The performance of the M-AUE vehicles illustrates their novel capability for measuring submesoscale dynamics.

  12. A swarm of autonomous miniature underwater robot drifters for exploring submesoscale ocean dynamics

    PubMed Central

    Jaffe, Jules S.; Franks, Peter J. S.; Roberts, Paul L. D.; Mirza, Diba; Schurgers, Curt; Kastner, Ryan; Boch, Adrien

    2017-01-01

    Measuring the ever-changing 3-dimensional (3D) motions of the ocean requires simultaneous sampling at multiple locations. In particular, sampling the complex, nonlinear dynamics associated with submesoscales (<1–10 km) requires new technologies and approaches. Here we introduce the Mini-Autonomous Underwater Explorer (M-AUE), deployed as a swarm of 16 independent vehicles whose 3D trajectories are measured near-continuously, underwater. As the vehicles drift with the ambient flow or execute preprogrammed vertical behaviours, the simultaneous measurements at multiple, known locations resolve the details of the flow within the swarm. We describe the design, construction, control and underwater navigation of the M-AUE. A field programme in the coastal ocean using a swarm of these robots programmed with a depth-holding behaviour provides a unique test of a physical–biological interaction leading to plankton patch formation in internal waves. The performance of the M-AUE vehicles illustrates their novel capability for measuring submesoscale dynamics. PMID:28117837

  13. A swarm of autonomous miniature underwater robot drifters for exploring submesoscale ocean dynamics

    NASA Astrophysics Data System (ADS)

    Jaffe, Jules S.; Franks, Peter J. S.; Roberts, Paul L. D.; Mirza, Diba; Schurgers, Curt; Kastner, Ryan; Boch, Adrien

    2017-01-01

    Measuring the ever-changing 3-dimensional (3D) motions of the ocean requires simultaneous sampling at multiple locations. In particular, sampling the complex, nonlinear dynamics associated with submesoscales (<1-10 km) requires new technologies and approaches. Here we introduce the Mini-Autonomous Underwater Explorer (M-AUE), deployed as a swarm of 16 independent vehicles whose 3D trajectories are measured near-continuously, underwater. As the vehicles drift with the ambient flow or execute preprogrammed vertical behaviours, the simultaneous measurements at multiple, known locations resolve the details of the flow within the swarm. We describe the design, construction, control and underwater navigation of the M-AUE. A field programme in the coastal ocean using a swarm of these robots programmed with a depth-holding behaviour provides a unique test of a physical-biological interaction leading to plankton patch formation in internal waves. The performance of the M-AUE vehicles illustrates their novel capability for measuring submesoscale dynamics.

  14. Real Time Adaptive Control of an Autonomous Underwater Vehicle (AUV)

    DTIC Science & Technology

    1989-09-01

    design of a control system f or the AUV, since knowledge of an accurate dynamic model is in general the basis of a reliable control design. Also, tests...designer the possibility of using this simple nominal model, possibly linear while still preserving the global stability ol. he controlled system . 3...control system . The parameters a, c arid K0 in (2.4a) depend on the operating 9 conditions (speed, primarily) of the vehicle, and can be determined on the

  15. Event Response by Observatory-based Autonomous Underwater Vehicles: Scientific Need and Technological Capabilities

    NASA Astrophysics Data System (ADS)

    Yoerger, D. R.; Bradley, A. M.

    2001-12-01

    Autonomous Underwater Vehicles (AUVs) operated from a subsea observatory can provide crucial capabilities for observing dynamic events, such as the large plumes that accompany tectonic or volcanic events. An AUV docked to an observatory node could be recharged and while docked would have continuous communication with researchers ashore. Such a vehicle could reach an event long before we could mount a response with a ship and perhaps quicker than could an AUV launched from an aircraft. Autonomous Underwater Vehicles can be built in a variety of shapes and sizes, which translate into a wide range of capabilities in terms of speed, range, maneuverability, and payload. Likewise, we have a variety of choices for the design of docking stations, navigational infrastructure, in-situ sensing systems and communications capability. All these elements also greatly drive the cost of an AUV, and the best approach could entail providing a mix of vehicles with complementary capabilities. This presentation examines how observatory system architecture, AUV performance characteristics, and sensing capabilities will effect our ability to achieve scientific goals during an event response. This presentation aims to promote a dialogue between engineers and scientists to determine how such an observatory capability can best address scientific needs.

  16. Active Visual SLAM with Exploration for Autonomous Underwater Navigation

    DTIC Science & Technology

    2012-01-01

    reprojection error using a plane induced homography model (Hartley and Zisserman, 2000). The optimization is performed over the homography parameters (R...the projection matrices. (b) For homography, the point is constrained on a plane (π), and SBA solves for the optimal reprojected points (ûi), plane ...Essential matrix Camera i Camera j π x u u H i j iju = H u (b) Homography coordinate version of ûin). The plane induced homography, H, is written in terms

  17. Three Dimensional Guidance for the NPS Autonomous Underwater Vehicle

    DTIC Science & Technology

    1991-09-01

    The pool bottom consists of two parts that are of roughly equal size. The first is a flat surface that is of the maximum depth of the pool. The...above, the simulator is designed to model the actual AUV. This goal has, for the most part , been realized. However, there are certain aspects between...reduce the properties discussed above to a single scaler function, V (x) . This function must conform to the following properties: * V (x) is continuous

  18. High spatial resolution mapping of water quality and bathymetry with an autonomous underwater vehicle

    NASA Astrophysics Data System (ADS)

    Pampalone, Vincenzo; Milici, Barbara

    2015-12-01

    The drone Ecomapper AUV (Autonomous Underwater Vehicle) is a rare example of highly technological instrument in the environmental coastal monitoring field. The YSI EcoMapper is a one-man deployable, Autonomous Underwater Vehicle (AUV) designed to collect bathymetry and water quality data. The submarine-like vehicle follows a programmed course and employs sensors mounted in the nose to record pertinent information. Once the vehicle has started its mission, it operates independently of the user and utilizes GPS waypoints navigation to complete its programmed course. Throughout the course, the vehicle constantly steers toward the line drawn in the mission planning software (VectorMap), essentially following a more accurate road of coordinates instead of transversing waypoint-to-waypoint. It has been equipped with a Doppler Velocity Log (DVL) to increase its underwater navigation accuracy. Potential EcoMapper applications include baseline environmental mapping in freshwater, estuarine or near-coastal environments, bathymetric mapping, dissolved oxygen studies, event monitoring (algal blooms, storm impacts, low dissolved oxygen), non-point source studies, point-source dispersion mapping, security, search & rescue, inspection, shallow water mapping, thermal dissipation mapping of cooling outfalls, trace-dye studies. The AUV is used in the coastal area of the Augusta Bay (Italy), located in the eastern part of Sicily. Due to the heavy contamination generated by the several chemical and petrochemical industries active in the zone, the harbour was declared a Contaminated Site of National Interest. The ecomapper allows for a simultaneous data collection of water quality and bathymetric data providing a complete environmental mapping system of the Harbour.

  19. Multi-AUV Target Search Based on Bioinspired Neurodynamics Model in 3-D Underwater Environments.

    PubMed

    Cao, Xiang; Zhu, Daqi; Yang, Simon X

    2016-11-01

    Target search in 3-D underwater environments is a challenge in multiple autonomous underwater vehicles (multi-AUVs) exploration. This paper focuses on an effective strategy for multi-AUV target search in the 3-D underwater environments with obstacles. First, the Dempster-Shafer theory of evidence is applied to extract information of environment from the sonar data to build a grid map of the underwater environments. Second, a topologically organized bioinspired neurodynamics model based on the grid map is constructed to represent the dynamic environment. The target globally attracts the AUVs through the dynamic neural activity landscape of the model, while the obstacles locally push the AUVs away to avoid collision. Finally, the AUVs plan their search path to the targets autonomously by a steepest gradient descent rule. The proposed algorithm deals with various situations, such as static targets search, dynamic targets search, and one or several AUVs break down in the 3-D underwater environments with obstacles. The simulation results show that the proposed algorithm is capable of guiding multi-AUV to achieve search task of multiple targets with higher efficiency and adaptability compared with other algorithms.

  20. Development of an autonomous underwater vehicle R1 with a closed cycle diesel engine

    SciTech Connect

    Obara, Takashi; Yamamoto, Kitao; Ura, Tamaki; Maeda, Hisaaki; Yamato, Hiroyuki

    1994-12-31

    This paper presents the current state of a project, which started in 1990 to develop an autonomous underwater free swimming robot equipped with a Closed Cycle Diesel Engine (CCDE) for long term survey of mid-ocean ridges. The distinctive feature of CCDE is robustness and low cost for construction and operation. The robot structure and configuration of a torpedo-shaped hull are described in detail including newly developed thrusters using compact DC brushless motors. As the robot aims to swim in the vicinity of the seabed, an Inertial Navigation system (INS) co-operates with a doppler sonar system to make accurate navigation for detailed research. The CCDE system for the robot has been completed and its submerged tests are underway in a water pool.

  1. Autonomous Underwater Vehicle Survey Design for Monitoring Carbon Capture and Storage Sites

    NASA Astrophysics Data System (ADS)

    Bull, J. M.; Cevatoglu, M.; Connelly, D.; Wright, I. C.; McPhail, S.; Shitashima, K.

    2013-12-01

    Long-term monitoring of sub-seabed Carbon Capture and Storage (CCS) sites will require systems that are flexible, independent, and have long-endurance. In this presentation we will discuss the utility of autonomous underwater vehicles equipped with different sensor packages in monitoring storage sites. We will present data collected using Autosub AUV, as part of the ECO2 project, from the Sleipner area of the North Sea. The Autosub AUV was equipped with sidescan sonar, an EM2000 multibeam systems, a Chirp sub-bottom profiler, and a variety of chemical sensors. Our presentation will focus on survey design, and the simultaneous use of multiple sensor packages in environmental monitoring on the continental shelf.

  2. H∞ robust fault-tolerant controller design for an autonomous underwater vehicle's navigation control system

    NASA Astrophysics Data System (ADS)

    Cheng, Xiang-Qin; Qu, Jing-Yuan; Yan, Zhe-Ping; Bian, Xin-Qian

    2010-03-01

    In order to improve the security and reliability for autonomous underwater vehicle (AUV) navigation, an H∞ robust fault-tolerant controller was designed after analyzing variations in state-feedback gain. Operating conditions and the design method were then analyzed so that the control problem could be expressed as a mathematical optimization problem. This permitted the use of linear matrix inequalities (LMI) to solve for the H∞ controller for the system. When considering different actuator failures, these conditions were then also mathematically expressed, allowing the H∞ robust controller to solve for these events and thus be fault-tolerant. Finally, simulation results showed that the H∞ robust fault-tolerant controller could provide precise AUV navigation control with strong robustness.

  3. A Dynamic Bioinspired Neural Network Based Real-Time Path Planning Method for Autonomous Underwater Vehicles

    PubMed Central

    2017-01-01

    Real-time path planning for autonomous underwater vehicle (AUV) is a very difficult and challenging task. Bioinspired neural network (BINN) has been used to deal with this problem for its many distinct advantages: that is, no learning process is needed and realization is also easy. However, there are some shortcomings when BINN is applied to AUV path planning in a three-dimensional (3D) unknown environment, including complex computing problem when the environment is very large and repeated path problem when the size of obstacles is bigger than the detection range of sensors. To deal with these problems, an improved dynamic BINN is proposed in this paper. In this proposed method, the AUV is regarded as the core of the BINN and the size of the BINN is based on the detection range of sensors. Then the BINN will move with the AUV and the computing could be reduced. A virtual target is proposed in the path planning method to ensure that the AUV can move to the real target effectively and avoid big-size obstacles automatically. Furthermore, a target attractor concept is introduced to improve the computing efficiency of neural activities. Finally, some experiments are conducted under various 3D underwater environments. The experimental results show that the proposed BINN based method can deal with the real-time path planning problem for AUV efficiently. PMID:28255297

  4. A Dynamic Bioinspired Neural Network Based Real-Time Path Planning Method for Autonomous Underwater Vehicles.

    PubMed

    Ni, Jianjun; Wu, Liuying; Shi, Pengfei; Yang, Simon X

    2017-01-01

    Real-time path planning for autonomous underwater vehicle (AUV) is a very difficult and challenging task. Bioinspired neural network (BINN) has been used to deal with this problem for its many distinct advantages: that is, no learning process is needed and realization is also easy. However, there are some shortcomings when BINN is applied to AUV path planning in a three-dimensional (3D) unknown environment, including complex computing problem when the environment is very large and repeated path problem when the size of obstacles is bigger than the detection range of sensors. To deal with these problems, an improved dynamic BINN is proposed in this paper. In this proposed method, the AUV is regarded as the core of the BINN and the size of the BINN is based on the detection range of sensors. Then the BINN will move with the AUV and the computing could be reduced. A virtual target is proposed in the path planning method to ensure that the AUV can move to the real target effectively and avoid big-size obstacles automatically. Furthermore, a target attractor concept is introduced to improve the computing efficiency of neural activities. Finally, some experiments are conducted under various 3D underwater environments. The experimental results show that the proposed BINN based method can deal with the real-time path planning problem for AUV efficiently.

  5. Electrolocation-based obstacle avoidance and autonomous navigation in underwater environments

    NASA Astrophysics Data System (ADS)

    Dimble, Kedar D.

    Weakly electric fish are capable of performing obstacle avoidance in dark and complex aquatic environments efficiently using a navigation technique known as electrolocation. That is, electric fish infer relevant information about surrounding obstacles from the perturbations that these obstacles impart to their self-generated electric field. This dissertation draws inspiration from electrolocation to demonstrate unmapped reflexive obstacle avoidance in underwater environments. The perturbation signal, called the electric image, contains the spatial information of the perturbing objects regarding their location, size, conductivity etc. Electrostatic equations elucidate the concept of electrolocation and the mechanism of obstacle detection using electric field perturbations. Spatial decomposition of an electric image using Wide-Field Integration processing extracts relative proximity information about the obstacles. The electric field source is changed to an oscillatory one and a quasistatic approach is taken. Simulations were performed in straight tunnel, cluttered corridor and an obstacle field. Experimental validation was conducted with a setup comprising a tank, a computer-controlled gantry system and an electro-sensor. Consistency between the simulations and the experiments was maintained by recreating similar environments. Simulations using both the electrostatic and the quasistatic approach demonstrate that the algorithm is capable of performing various maneuvers like tunnel centering, wall following and clutter navigation. The experimental results agree with the simulation results and validate the efficacy of the approach in performing obstacle avoidance. The presented approach is computationally lightweight and readily implementable, making underwater autonomous navigation in real-time feasible.

  6. Autonomous Learner Model Resource Book

    ERIC Educational Resources Information Center

    Betts, George T.; Carey, Robin J.; Kapushion, Blanche M.

    2016-01-01

    "Autonomous Learner Model Resource Book" includes activities and strategies to support the development of autonomous learners. More than 40 activities are included, all geared to the emotional, social, cognitive, and physical development of students. Teachers may use these activities and strategies with the entire class, small groups, or…

  7. Autonomous Learner Model Resource Book

    ERIC Educational Resources Information Center

    Betts, George T.; Carey, Robin J.; Kapushion, Blanche M.

    2016-01-01

    "Autonomous Learner Model Resource Book" includes activities and strategies to support the development of autonomous learners. More than 40 activities are included, all geared to the emotional, social, cognitive, and physical development of students. Teachers may use these activities and strategies with the entire class, small groups, or…

  8. Optimizing Autonomous Underwater Vehicles' Survey for Reconstruction of an Ocean Field that Varies in Space and Time

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Bellingham, J. G.; Davis, R. E.; Chao, Y.

    2005-12-01

    In this paper we present the results of applying a survey error analysis tool to the Monterey Bay 2003 experiment data. The objective is to learn how to optimize the use of autonomous mobile sensors to sample and reconstruct a spatio-temporal process. Autonomous Underwater Vehicle's (AUV's) survey duration and speed, and therefore sampling density, are constrained by the vehicle's battery capacity, hotel load, and drag. An oceanographic field varies over the survey duration, so the oceanographer must choose between a slow, high-resolution survey, and a fast, low-resolution survey. When reconstructing the field, we encounter temporal smearing and spatial aliasing errors. Thus we need to optimize AUV speed and sampling density to minimize the reconstruction error. In previous work, an error metric was derived as a function of the vehicle's speed and sampling grid spacing. On the error map, the optimum speed and sampling grid spacing can be found within the battery capacity envelope. In the Autonomous Ocean Sampling Network (AOSN) Monterey Bay 2003 experiment, AUVs were deployed to measure temperature, salinity, and other quantities. During the experiment, JPL's Regional Ocean Modeling System (ROMS) assimilated in-situ data and provided field forecasts. In this paper, we apply the AUV survey error analysis tool on the model and experimental data from this experiment, in order to optimize AUV survey strategies. Using AUV-acquired samples, we reconstruct the ocean fields by the methods of objective mapping and Empirical Orthogonal Functions (EOFs). The actual reconstruction errors are compared with the predicted AUV survey error, and the differences are discussed. This provides a useful tool for optimizing grid surveys, and also provides a baseline against which targeted sampling algorithms can be compared.

  9. An Optimized, Data Distribution Service-Based Solution for Reliable Data Exchange Among Autonomous Underwater Vehicles.

    PubMed

    Rodríguez-Molina, Jesús; Bilbao, Sonia; Martínez, Belén; Frasheri, Mirgita; Cürüklü, Baran

    2017-08-05

    Major challenges are presented when managing a large number of heterogeneous vehicles that have to communicate underwater in order to complete a global mission in a cooperative manner. In this kind of application domain, sending data through the environment presents issues that surpass the ones found in other overwater, distributed, cyber-physical systems (i.e., low bandwidth, unreliable transport medium, data representation and hardware high heterogeneity). This manuscript presents a Publish/Subscribe-based semantic middleware solution for unreliable scenarios and vehicle interoperability across cooperative and heterogeneous autonomous vehicles. The middleware relies on different iterations of the Data Distribution Service (DDS) software standard and their combined work between autonomous maritime vehicles and a control entity. It also uses several components with different functionalities deemed as mandatory for a semantic middleware architecture oriented to maritime operations (device and service registration, context awareness, access to the application layer) where other technologies are also interweaved with middleware (wireless communications, acoustic networks). Implementation details and test results, both in a laboratory and a deployment scenario, have been provided as a way to assess the quality of the system and its satisfactory performance.

  10. Target re-acquisition using acoustic features with an autonomous underwater vehicle-borne sonar

    NASA Astrophysics Data System (ADS)

    Edwards, Joseph; Schmidt, Henrik

    2003-10-01

    Concurrent mapping and localization (CML) is a technique for unsupervised feature-based mapping of unknown environments, and is an essential tool for autonomous robots. For land robots, CML can be applied using video, laser, or acoustic sensors, while for autonomous underwater vehicles (AUVs) the only effective transducer in most situations is sonar. In the Generic Oceanographic Array Technology Sonar (GOATS) experiment series, CML was effectively demonstrated using a single AUV. A further hurdle in the full implementation of AUV minehunting is to re-acquire and identify targets of interest. Target re-acquisition allows other vehicles to be called into a target location to further investigate with adaptive sonar geometries or alternative sensor suites designed for classification. In this work, the features in the CML-generated map are extended from only spatial coordinates to include acoustic features such as spectral response. It is demonstrated that the inclusion of acoustic features aids in the global positioning within the map, although the fine positioning is still accomplished through standard CML. In addition, areas that are sparsely populated with targets, e.g., a sandy coastline, are shown to be more readily navigable using acoustic features.

  11. An Optimized, Data Distribution Service-Based Solution for Reliable Data Exchange Among Autonomous Underwater Vehicles

    PubMed Central

    Bilbao, Sonia; Martínez, Belén; Frasheri, Mirgita; Cürüklü, Baran

    2017-01-01

    Major challenges are presented when managing a large number of heterogeneous vehicles that have to communicate underwater in order to complete a global mission in a cooperative manner. In this kind of application domain, sending data through the environment presents issues that surpass the ones found in other overwater, distributed, cyber-physical systems (i.e., low bandwidth, unreliable transport medium, data representation and hardware high heterogeneity). This manuscript presents a Publish/Subscribe-based semantic middleware solution for unreliable scenarios and vehicle interoperability across cooperative and heterogeneous autonomous vehicles. The middleware relies on different iterations of the Data Distribution Service (DDS) software standard and their combined work between autonomous maritime vehicles and a control entity. It also uses several components with different functionalities deemed as mandatory for a semantic middleware architecture oriented to maritime operations (device and service registration, context awareness, access to the application layer) where other technologies are also interweaved with middleware (wireless communications, acoustic networks). Implementation details and test results, both in a laboratory and a deployment scenario, have been provided as a way to assess the quality of the system and its satisfactory performance. PMID:28783049

  12. On Modeling Eavesdropping Attacks in Underwater Acoustic Sensor Networks †

    PubMed Central

    Wang, Qiu; Dai, Hong-Ning; Li, Xuran; Wang, Hao; Xiao, Hong

    2016-01-01

    The security and privacy of underwater acoustic sensor networks has received extensive attention recently due to the proliferation of underwater activities. This paper proposes an analytical model to investigate the eavesdropping attacks in underwater acoustic sensor networks. Our analytical framework considers the impacts of various underwater acoustic channel conditions (such as the acoustic signal frequency, spreading factor and wind speed) and different hydrophones (isotropic hydrophones and array hydrophones) in terms of network nodes and eavesdroppers. We also conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Empirical results show that our proposed model is quite accurate. In addition, our results also imply that the eavesdropping probability heavily depends on both the underwater acoustic channel conditions and the features of hydrophones. PMID:27213379

  13. On Modeling Eavesdropping Attacks in Underwater Acoustic Sensor Networks.

    PubMed

    Wang, Qiu; Dai, Hong-Ning; Li, Xuran; Wang, Hao; Xiao, Hong

    2016-05-18

    The security and privacy of underwater acoustic sensor networks has received extensive attention recently due to the proliferation of underwater activities. This paper proposes an analytical model to investigate the eavesdropping attacks in underwater acoustic sensor networks. Our analytical framework considers the impacts of various underwater acoustic channel conditions (such as the acoustic signal frequency, spreading factor and wind speed) and different hydrophones (isotropic hydrophones and array hydrophones) in terms of network nodes and eavesdroppers. We also conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Empirical results show that our proposed model is quite accurate. In addition, our results also imply that the eavesdropping probability heavily depends on both the underwater acoustic channel conditions and the features of hydrophones.

  14. Subsea Cable Tracking by Autonomous Underwater Vehicle with Magnetic Sensing Guidance.

    PubMed

    Xiang, Xianbo; Yu, Caoyang; Niu, Zemin; Zhang, Qin

    2016-08-20

    The changes of the seabed environment caused by a natural disaster or human activities dramatically affect the life span of the subsea buried cable. It is essential to track the cable route in order to inspect the condition of the buried cable and protect its surviving seabed environment. The magnetic sensor is instrumental in guiding the remotely-operated vehicle (ROV) to track and inspect the buried cable underseas. In this paper, a novel framework integrating the underwater cable localization method with the magnetic guidance and control algorithm is proposed, in order to enable the automatic cable tracking by a three-degrees-of-freedom (3-DOF) under-actuated autonomous underwater vehicle (AUV) without human beings in the loop. The work relies on the passive magnetic sensing method to localize the subsea cable by using two tri-axial magnetometers, and a new analytic formulation is presented to compute the heading deviation, horizontal offset and buried depth of the cable. With the magnetic localization, the cable tracking and inspection mission is elaborately constructed as a straight-line path following control problem in the horizontal plane. A dedicated magnetic line-of-sight (LOS) guidance is built based on the relative geometric relationship between the vehicle and the cable, and the feedback linearizing technique is adopted to design a simplified cable tracking controller considering the side-slip effects, such that the under-actuated vehicle is able to move towards the subsea cable and then inspect its buried environment, which further guides the environmental protection of the cable by setting prohibited fishing/anchoring zones and increasing the buried depth. Finally, numerical simulation results show the effectiveness of the proposed magnetic guidance and control algorithm on the envisioned subsea cable tracking and the potential protection of the seabed environment along the cable route.

  15. Subsea Cable Tracking by Autonomous Underwater Vehicle with Magnetic Sensing Guidance

    PubMed Central

    Xiang, Xianbo; Yu, Caoyang; Niu, Zemin; Zhang, Qin

    2016-01-01

    The changes of the seabed environment caused by a natural disaster or human activities dramatically affect the life span of the subsea buried cable. It is essential to track the cable route in order to inspect the condition of the buried cable and protect its surviving seabed environment. The magnetic sensor is instrumental in guiding the remotely-operated vehicle (ROV) to track and inspect the buried cable underseas. In this paper, a novel framework integrating the underwater cable localization method with the magnetic guidance and control algorithm is proposed, in order to enable the automatic cable tracking by a three-degrees-of-freedom (3-DOF) under-actuated autonomous underwater vehicle (AUV) without human beings in the loop. The work relies on the passive magnetic sensing method to localize the subsea cable by using two tri-axial magnetometers, and a new analytic formulation is presented to compute the heading deviation, horizontal offset and buried depth of the cable. With the magnetic localization, the cable tracking and inspection mission is elaborately constructed as a straight-line path following control problem in the horizontal plane. A dedicated magnetic line-of-sight (LOS) guidance is built based on the relative geometric relationship between the vehicle and the cable, and the feedback linearizing technique is adopted to design a simplified cable tracking controller considering the side-slip effects, such that the under-actuated vehicle is able to move towards the subsea cable and then inspect its buried environment, which further guides the environmental protection of the cable by setting prohibited fishing/anchoring zones and increasing the buried depth. Finally, numerical simulation results show the effectiveness of the proposed magnetic guidance and control algorithm on the envisioned subsea cable tracking and the potential protection of the seabed environment along the cable route. PMID:27556465

  16. Integrating Multiple Autonomous Underwater Vessels, Surface Vessels and Aircraft into Oceanographic Research Vessel Operations

    NASA Astrophysics Data System (ADS)

    McGillivary, P. A.; Borges de Sousa, J.; Martins, R.; Rajan, K.

    2012-12-01

    Autonomous platforms are increasingly used as components of Integrated Ocean Observing Systems and oceanographic research cruises. Systems deployed can include gliders or propeller-driven autonomous underwater vessels (AUVs), autonomous surface vessels (ASVs), and unmanned aircraft systems (UAS). Prior field campaigns have demonstrated successful communication, sensor data fusion and visualization for studies using gliders and AUVs. However, additional requirements exist for incorporating ASVs and UASs into ship operations. For these systems to be optimally integrated into research vessel data management and operational planning systems involves addressing three key issues: real-time field data availability, platform coordination, and data archiving for later analysis. A fleet of AUVs, ASVs and UAS deployed from a research vessel is best operated as a system integrated with the ship, provided communications among them can be sustained. For this purpose, Disruptive Tolerant Networking (DTN) software protocols for operation in communication-challenged environments help ensure reliable high-bandwidth communications. Additionally, system components need to have considerable onboard autonomy, namely adaptive sampling capabilities using their own onboard sensor data stream analysis. We discuss Oceanographic Decision Support System (ODSS) software currently used for situational awareness and planning onshore, and in the near future event detection and response will be coordinated among multiple vehicles. Results from recent field studies from oceanographic research vessels using AUVs, ASVs and UAS, including the Rapid Environmental Picture (REP-12) cruise, are presented describing methods and results for use of multi-vehicle communication and deliberative control networks, adaptive sampling with single and multiple platforms, issues relating to data management and archiving, and finally challenges that remain in addressing these technological issues. Significantly, the

  17. a Modular Geometric Model for Underwater Photogrammetry

    NASA Astrophysics Data System (ADS)

    Maas, H.-G.

    2015-04-01

    Underwater applications of photogrammetric measurement techniques usually need to deal with multimedia photogrammetry aspects, which are characterized by the necessity of handling optical rays that are broken at interfaces between optical media with different refrative indices according to Snell's Law. This so-called multimedia geometry has to be incorporated into geometric models in order to achieve correct measurement results. The paper shows a flexible yet strict geometric model for the handling of refraction effects on the optical path, which can be implemented as a module into photogrammetric standard tools such as spatial resection, spatial intersection, bundle adjustment or epipolar line computation. The module is especially well suited for applications, where an object in water is observed by cameras in air through one or more plane parallel glass interfaces, as it allows for some simplifications here.

  18. 3D Photo Mosaicing of Tagiri Shallow Vent Field by an Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Maki, Toshihiro; Kondo, Hayato; Ura, Tamaki; Sakamaki, Takashi; Mizushima, Hayato; Yanagisawa, Masao

    Although underwater visual observation is an ideal method for detailed survey of seafloors, it is currently a costly process that requires the use of Remotely Operated Vehicles (ROVs) or Human Occupied Vehicles (HOVs), and can cover only a limited area. This paper proposes an innovative method to navigate an autonomous underwater vehicle (AUV) to create both 2D and 3D photo mosaics of seafloors with high positioning accuracy without using any vision-based matching. The vehicle finds vertical pole-like acoustic reflectors to use as positioning landmarks using a profiling sonar based on a SLAM (Simultaneous Localization And Mapping) technique. These reflectors can be either artificial or natural objects, and so the method can be applied to shallow vent fields where conventional acoustic positioning is difficult, since bubble plumes can also be used as landmarks as well as artificial reflectors. Path-planning is performed in real-time based on the positions and types of landmarks so as to navigate safely and stably using landmarks of different types (artificial reflector or bubble plume) found at arbitrary times and locations. Terrain tracker switches control reference between depth and altitude from the seafloor based on a local map of hazardous area created in real-time using onboard perceptual sensors, in order to follow rugged terrains at an altitude of 1 to 2 meters, as this range is ideal for visual observation. The method was implemented in the AUV Tri-Dog 1 and experiments were carried out at Tagiri vent field, Kagoshima Bay in Japan. The AUV succeeded in fully autonomous observation for more than 160 minutes to create a photo mosaic with an area larger than 600 square meters, which revealed the spatial distribution of detailed features such as tube-worm colonies, bubble plumes and bacteria mats. A fine bathymetry of the same area was also created using a light-section ranging system mounted on the vehicle. Finally a 3 D representation of the environment was

  19. Advancing Underwater Acoustic Communication for Autonomous Distributed Networks via Sparse Channel Sensing, Coding, and Navigation Support

    DTIC Science & Technology

    2011-09-30

    channel interference mitigation for underwater acoustic MIMO-OFDM. 3) Turbo equalization for OFDM modulated physical layer network coding. 4) Blind CFO...Localization and tracking of underwater physical systems. 7) NAMS: A networked acoustic modem system for underwater applications . 8) OFDM receiver design in...3) Turbo Equalization for OFDM Modulated Physical Layer Network Coding. We have investigated a practical orthogonal frequency division multiplexing

  20. Area reconnaissance, object relocation, and classification using cooperating autonomous underwater vehicles

    NASA Astrophysics Data System (ADS)

    Trimble, Gary M.

    1999-07-01

    Lockheed Martin Perry Technologies (Perry) is currently demonstrating the employment of small inexpensive Autonomous Underwater Vehicles (AUVs) for area reconnaissance and object relation/classification in Shallow Water (SW) and Very Shallow Water (VSW) environments. An MIT Sea Grant Odyssey II AUV, equipped with side-scan sonar and automated on-vehicle sensor processing hardware and software is employed as an area reconnaissance platform, transmitting detection information to a second concurrently-operating inspection-capable. The conjunctive use of each platform's characteristics optimizes search and evaluation of subsea objects. A unique facet of this Cooperating AUV research addresses the employment of the vehicles in an unstructured navigation environment which does not employ any off-vehicle positioning aids in the completion of search and the derivation of revisit coordinates. All navigation and positioning is vehicle based, employing a combination of Global Positioning System coordinates, inertial measurement, and Doppler measured velocity using coordinates and classification information which may contribute to the classification solution which are derived and acoustically transmitted by the Odyssey search AUV, the CETUS intervention AUV dynamically derives and revises plans which optimize its capability to revisit, localize, and classify targets. This program is intended to provide a base measurements of effectiveness using proven existing vehicles and capabilities, and the means to evaluate and demonstrate the advantages of cooperative sensing from multiple platforms for minimum time/maximum coverage of an area which support the goats of rapid area reconnaissance and evaluation. The ultimate goals of this program are to derive an rapidly deployable inexpensive autonomous reconnaissance and intervention capability for SW, VSW environments, supporting and possibly supplanting the use of ships or other manned assets for many dangerous difficult or expensive

  1. Design and Implementation of a Biomimetic Turtle Hydrofoil for an Autonomous Underwater Vehicle

    PubMed Central

    Font, Davinia; Tresanchez, Marcel; Siegentahler, Cedric; Pallejà, Tomàs; Teixidó, Mercè; Pradalier, Cedric; Palacin, Jordi

    2011-01-01

    This paper presents the design and implementation of a turtle hydrofoil for an Autonomous Underwater Vehicle (AUV). The final design of the AUV must have navigation performance like a turtle, which has also been the biomimetic inspiration for the design of the hydrofoil and propulsion system. The hydrofoil design is based on a National Advisory Committee for Aeronautics (NACA) 0014 hydrodynamic profile. During the design stage, four different propulsion systems were compared in terms of propulsion path, compactness, sealing and required power. The final implementation is based on a ball-and-socket mechanism because it is very compact and provides three degrees of freedom (DoF) to the hydrofoil with very few restrictions on the propulsion path. The propulsion obtained with the final implementation of the hydrofoil has been empirically evaluated in a water channel comparing different motion strategies. The results obtained have confirmed that the proposed turtle hydrofoil controlled with a mechanism with three DoF generates can be used in the future implementation of the planned AUV. PMID:22247660

  2. Measurement of sea-ice draft using upward-looking ADCP on an autonomous underwater vehicle

    NASA Astrophysics Data System (ADS)

    Banks, Christopher J.; Brandon, Mark A.; Garthwaite, Paul H.

    During March 2003, Autosub, an autonomous underwater vehicle (AUV) operated by the UK National Oceanography Centre, Southampton, was deployed under sea ice north of Thurston Island, Amundsen Sea, Antarctica (at ˜71° S, 100° W). The vehicle was fitted with an upward-looking 300 kHz acoustic Doppler current profiler (ADCP) to provide current velocity above the AUV. The ADCP also recorded ranges to the ocean-ice interface. Such data can be used to derive sea-ice draft by using a number of novel processing steps such as correcting for the coordinate systems of the ADCP unit and the vehicle as well as corrections for changes in sound speed. This paper outlines the processing stages required to obtain a probability density function (PDF) of sea-ice draft and presents PDFs for the region north of Thurston Island. The distribution of ice draft was found to be unimodal, with modes between 2.2 and 2.4 m. Given the uncertainty in sound speed, the limit of accuracy was estimated as ˜6 cm.

  3. An Effective Terrain Aided Navigation for Low-Cost Autonomous Underwater Vehicles.

    PubMed

    Zhou, Ling; Cheng, Xianghong; Zhu, Yixian; Dai, Chenxi; Fu, Jinbo

    2017-03-25

    Terrain-aided navigation is a potentially powerful solution for obtaining submerged position fixes for autonomous underwater vehicles. The application of terrain-aided navigation with high-accuracy inertial navigation systems has demonstrated meter-level navigation accuracy in sea trials. However, available sensors may be limited depending on the type of the mission. Such limitations, especially for low-grade navigation sensors, not only degrade the accuracy of traditional navigation systems, but further impact the ability to successfully employ terrain-aided navigation. To address this problem, a tightly-coupled navigation is presented to successfully estimate the critical sensor errors by incorporating raw sensor data directly into an augmented navigation system. Furthermore, three-dimensional distance errors are calculated, providing measurement updates through the particle filter for absolute and bounded position error. The development of the terrain aided navigation system is elaborated for a vehicle equipped with a non-inertial-grade strapdown inertial navigation system, a 4-beam Doppler Velocity Log range sensor and a sonar altimeter. Using experimental data for navigation performance evaluation in areas with different terrain characteristics, the experiment results further show that the proposed method can be successfully applied to the low-cost AUVs and significantly improves navigation performance.

  4. Infrastructure for thulium-170 isotope power systems for autonomous underwater vehicle fleets

    NASA Astrophysics Data System (ADS)

    Walter, C. E.

    1991-07-01

    The radioisotope thulium-170 is a safe and environmentally benign heat source for providing the high endurance and energy densities needed by advanced power systems for autonomous underwater vehicles (AUV). Thulium Isotope Power (TIP) systems have an endurance of approximately 3000 h, and gravimetric and volumetric energy densities of 3 times 10(exp 4) Wh/kg and 3 times 10(exp 8) Wh/cu m, respectively. These energy densities are more than 200 times higher than those currently provided by Ag-Zn battery technology. In order to capitalize on these performance levels with about one hundred AUVs in continuous use, it will be necessary to establish an infrastructure for isotope production and heat-source refurbishment. The infrastructure cost is not trivial, and studies are needed to determine its optimum configuration. The major component of the projected infrastructure is the nuclear reactor used to produce Tm- 170 by neutron absorption in Tm-169. The reactor design should ideally be optimized for TM-170 production. Using the byproduct waste heat beneficially would help defray the cost of isotope production. However, generating electric power with the reactor would compromise both the cost of electricity and the isotope production capacity. A coastal location for the reactor would be most convenient from end-use considerations, and the waste heat could be used to desalinate seawater in water-thirsty states.

  5. The use of autonomous underwater vehicles to map the variability of under-ice topography

    NASA Astrophysics Data System (ADS)

    Wadhams, Peter

    2012-03-01

    We review the development of autonomous underwater vehicle (AUV) use under sea ice to map the three-dimensional (3-D) structure of the ice underside. The author, after extensive experience in under-ice profiling from submarines using single-beam sonar, carried out the first under-ice sidescan sonar profiling from an AUV in 2002 in the Greenland Sea. This was followed in August 2004 by the first full multibeam sonar experiment, using Kongsberg EM2000 sonar aboard the Autosub-II vehicle off NE Greenland. Two experiments using a small Gavia vehicle deployed through holes in the ice followed in 2007 and 2008, in the Beaufort Sea and off Ellesmere Island. Examples of the 3-D imagery are shown, and the two approaches of using a large vehicle deployed from a ship and a small through-ice vehicle are compared and found to be complementary. The imagery has shown that although first-year (FY) ridges have the familiar shape of a triangular prism made of small ice blocks, multi-year (MY) ridges are found to be broken up by lead formation into a chain of individual large ice blocks rather than a coherent linear feature. New work and future plans are described.

  6. Design and implementation of a biomimetic turtle hydrofoil for an autonomous underwater vehicle.

    PubMed

    Font, Davinia; Tresanchez, Marcel; Siegentahler, Cedric; Pallejà, Tomàs; Teixidó, Mercè; Pradalier, Cedric; Palacin, Jordi

    2011-01-01

    This paper presents the design and implementation of a turtle hydrofoil for an Autonomous Underwater Vehicle (AUV). The final design of the AUV must have navigation performance like a turtle, which has also been the biomimetic inspiration for the design of the hydrofoil and propulsion system. The hydrofoil design is based on a National Advisory Committee for Aeronautics (NACA) 0014 hydrodynamic profile. During the design stage, four different propulsion systems were compared in terms of propulsion path, compactness, sealing and required power. The final implementation is based on a ball-and-socket mechanism because it is very compact and provides three degrees of freedom (DoF) to the hydrofoil with very few restrictions on the propulsion path. The propulsion obtained with the final implementation of the hydrofoil has been empirically evaluated in a water channel comparing different motion strategies. The results obtained have confirmed that the proposed turtle hydrofoil controlled with a mechanism with three DoF generates can be used in the future implementation of the planned AUV.

  7. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle.

    PubMed

    Milligan, R J; Morris, K J; Bett, B J; Durden, J M; Jones, D O B; Robert, K; Ruhl, H A; Bailey, D M

    2016-05-16

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850 m water depth) encompassing two spatial scales (1-10 km(2)) on and adjacent to a small abyssal hill (240 m elevation). The spatial distributions of the total fish fauna and that of the two dominant morphotypes (Coryphaenoides sp. 1 and C. profundicolus) appeared to be random, a result contrary to common expectation but consistent with previous predictions for these fishes. We estimated total fish density on the abyssal plain to be 723 individuals km(-2) (95% CI: 601-844). This estimate is higher, and likely more precise, than prior estimates from trawl catch and baited camera techniques (152 and 188 individuals km(-2) respectively). We detected no significant difference in fish density between abyssal hill and plain, nor did we detect any evidence for the existence of fish aggregations at any spatial scale assessed.

  8. Geomagnetic Navigation of Autonomous Underwater Vehicle Based on Multi-objective Evolutionary Algorithm.

    PubMed

    Li, Hong; Liu, Mingyong; Zhang, Feihu

    2017-01-01

    This paper presents a multi-objective evolutionary algorithm of bio-inspired geomagnetic navigation for Autonomous Underwater Vehicle (AUV). Inspired by the biological navigation behavior, the solution was proposed without using a priori information, simply by magnetotaxis searching. However, the existence of the geomagnetic anomalies has significant influence on the geomagnetic navigation system, which often disrupts the distribution of the geomagnetic field. An extreme value region may easily appear in abnormal regions, which makes AUV lost in the navigation phase. This paper proposes an improved bio-inspired algorithm with behavior constraints, for sake of making AUV escape from the abnormal region. First, the navigation problem is considered as the optimization problem. Second, the environmental monitoring operator is introduced, to determine whether the algorithm falls into the geomagnetic anomaly region. Then, the behavior constraint operator is employed to get out of the abnormal region. Finally, the termination condition is triggered. Compared to the state-of- the-art, the proposed approach effectively overcomes the disturbance of the geomagnetic abnormal. The simulation result demonstrates the reliability and feasibility of the proposed approach in complex environments.

  9. Design and implementation of cooperative autonomous underwater vehicles for Antarctic exploration

    NASA Astrophysics Data System (ADS)

    Cadena, A.

    2011-06-01

    The present work describes the development of two collaborative Autonomous Underwater Vehicles (AUV) for Antarctic exploration to use them in the Ecuadorian Expeditions to the Scientific Base Pedro Vicente Maldonado in Antarctica. One vehicle is an AUV, called TAUV, with classical torpedo architecture, can work as a platform to transport scientific payload in a determined path in open waters. The TAUV length is 2m and diameter of 0.16m and has got three degree of freedom: pitch, yaw and surge. The vehicle achieves stable control with a set of three pairs of control planes. The other vehicle is an AUV, called HAUV, with Hybrid architecture that combines the best characteristics of the ROV and AUV, high stability in the water column, high maneuverability at low velocity without control planes and efficient hydrodynamics. The HAUV length is less than 1.50 m. The propulsion module is formed by four thrusters, three axial and one oriented vertically, this configuration gives to the HAUV three degrees of freedom: heave, surge and yaw. This vehicle can works as a ROV or an AUV. The hybrid configuration features the vehicle to explore dangerous areas near to the glacier wall. Three collaborative behaviors are discussed: formation flying, point inspection near to the glacier wall, replacement of a missing vehicle. Results of some systems of the TAUV and HAUV from laboratory, sea trials in tropical waters and Antarctic environment are show.

  10. An Effective Terrain Aided Navigation for Low-Cost Autonomous Underwater Vehicles

    PubMed Central

    Zhou, Ling; Cheng, Xianghong; Zhu, Yixian; Dai, Chenxi; Fu, Jinbo

    2017-01-01

    Terrain-aided navigation is a potentially powerful solution for obtaining submerged position fixes for autonomous underwater vehicles. The application of terrain-aided navigation with high-accuracy inertial navigation systems has demonstrated meter-level navigation accuracy in sea trials. However, available sensors may be limited depending on the type of the mission. Such limitations, especially for low-grade navigation sensors, not only degrade the accuracy of traditional navigation systems, but further impact the ability to successfully employ terrain-aided navigation. To address this problem, a tightly-coupled navigation is presented to successfully estimate the critical sensor errors by incorporating raw sensor data directly into an augmented navigation system. Furthermore, three-dimensional distance errors are calculated, providing measurement updates through the particle filter for absolute and bounded position error. The development of the terrain aided navigation system is elaborated for a vehicle equipped with a non-inertial-grade strapdown inertial navigation system, a 4-beam Doppler Velocity Log range sensor and a sonar altimeter. Using experimental data for navigation performance evaluation in areas with different terrain characteristics, the experiment results further show that the proposed method can be successfully applied to the low-cost AUVs and significantly improves navigation performance. PMID:28346346

  11. Formation Learning Control of Multiple Autonomous Underwater Vehicles With Heterogeneous Nonlinear Uncertain Dynamics.

    PubMed

    Yuan, Chengzhi; Licht, Stephen; He, Haibo

    2017-09-26

    In this paper, a new concept of formation learning control is introduced to the field of formation control of multiple autonomous underwater vehicles (AUVs), which specifies a joint objective of distributed formation tracking control and learning/identification of nonlinear uncertain AUV dynamics. A novel two-layer distributed formation learning control scheme is proposed, which consists of an upper-layer distributed adaptive observer and a lower-layer decentralized deterministic learning controller. This new formation learning control scheme advances existing techniques in three important ways: 1) the multi-AUV system under consideration has heterogeneous nonlinear uncertain dynamics; 2) the formation learning control protocol can be designed and implemented by each local AUV agent in a fully distributed fashion without using any global information; and 3) in addition to the formation control performance, the distributed control protocol is also capable of accurately identifying the AUVs' heterogeneous nonlinear uncertain dynamics and utilizing experiences to improve formation control performance. Extensive simulations have been conducted to demonstrate the effectiveness of the proposed results.

  12. Mapping of Submerged Aquatic Vegetation Using Autonomous Underwater Vehicles in Nearshore Regions

    SciTech Connect

    Jones, Mark E.; Miller, Lee M.; Woodruff, Dana L.; Ewert, Daniel W.

    2007-10-02

    The use of an autonomous underwater vehicle (AUV) equipped with sidescan sonar was investigated for determining the boundaries of nearshore submerged aquatic vegetation beds, specifically eelgrass (Zostera marina). Shifts in eelgrass bed morphology, size, and distribution are used as indicators in monitoring programs to measure the impacts of coastal development and environmental stressors on eelgrass and to establish the efficacy of restoration programs. However, many monitoring programs necessarily extend over multiple-year time periods. Therefore, techniques that are easily reproducible, accurate, and cost-effective can demonstrate distinct advantages over some of the more traditional and labor-intensive methods, such as diver assessments and transects of shoot counts. Remote monitoring of eelgrass beds using satellite and aerial imagery has been demonstrated with moderate success, but requires groundtruthing, which can be costly and which frequently cannot delineate the deeper boundaries of eelgrass beds. One possible means for low-cost mapping is the use of AUVs equipped with acoustic imaging hardware. AUVs provide an ideal platform, because they can be deployed by small teams (two people), they are highly maneuverable, they can cover large areas over a relatively short time period (3knot operational speed), and they are equipped with multiple oceanographic instruments for correlated data collection. This paper describes the use of sidescan-equipped AUV technology deployed over multiple time periods at the same location where imagery of eelgrass beds was obtained and analyzed for comparative purposes.

  13. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle

    PubMed Central

    Milligan, R. J.; Morris, K. J.; Bett, B. J.; Durden, J. M.; Jones, D. O. B.; Robert, K.; Ruhl, H. A.; Bailey, D. M.

    2016-01-01

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850 m water depth) encompassing two spatial scales (1–10 km2) on and adjacent to a small abyssal hill (240 m elevation). The spatial distributions of the total fish fauna and that of the two dominant morphotypes (Coryphaenoides sp. 1 and C. profundicolus) appeared to be random, a result contrary to common expectation but consistent with previous predictions for these fishes. We estimated total fish density on the abyssal plain to be 723 individuals km−2 (95% CI: 601–844). This estimate is higher, and likely more precise, than prior estimates from trawl catch and baited camera techniques (152 and 188 individuals km−2 respectively). We detected no significant difference in fish density between abyssal hill and plain, nor did we detect any evidence for the existence of fish aggregations at any spatial scale assessed. PMID:27180728

  14. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle

    NASA Astrophysics Data System (ADS)

    Milligan, R. J.; Morris, K. J.; Bett, B. J.; Durden, J. M.; Jones, D. O. B.; Robert, K.; Ruhl, H. A.; Bailey, D. M.

    2016-05-01

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850 m water depth) encompassing two spatial scales (1-10 km2) on and adjacent to a small abyssal hill (240 m elevation). The spatial distributions of the total fish fauna and that of the two dominant morphotypes (Coryphaenoides sp. 1 and C. profundicolus) appeared to be random, a result contrary to common expectation but consistent with previous predictions for these fishes. We estimated total fish density on the abyssal plain to be 723 individuals km-2 (95% CI: 601-844). This estimate is higher, and likely more precise, than prior estimates from trawl catch and baited camera techniques (152 and 188 individuals km-2 respectively). We detected no significant difference in fish density between abyssal hill and plain, nor did we detect any evidence for the existence of fish aggregations at any spatial scale assessed.

  15. Localization and Tracking of Submerged Phytoplankton Bloom Patches by an Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Godin, M. A.; Ryan, J. P.; Zhang, Y.; Bellingham, J. G.

    2012-12-01

    Observing plankton in their drifting frame of reference permits effective studies of marine ecology from the perspective of microscopic life itself. By minimizing variation caused simply by advection, observations in a plankton-tracking frame of reference focus measurement capabilities on the processes that influence the life history of populations. Further, the patchy nature of plankton populations motivates use of sensor data in real-time to resolve patch boundaries and adapt observing resources accordingly. We have developed capabilities for population-centric plankton observation and sampling by autonomous underwater vehicles (AUVs). Our focus has been on phytoplankton populations, both because of their ecological significance - as the core of the oceanic food web and yet potentially harmful under certain bloom conditions, as well as the accessibility of their signal to simple optical sensing. During the first field deployment of these capabilities in 2010, we tracked a phytoplankton patch containing toxigenic diatoms and found that their toxicity correlated with exposure to resuspended sediments. However, this first deployment was labor intensive as the AUV drove in a pre-programmed pattern centered around a patch-marking drifter; it required a boat deployment of the patch-marking drifter and required full-time operators to periodically estimate of the position of the patch with respect to the drifter and adjust the AUV path accordingly. In subsequent field experiments during 2011 and 2012, the Tethys-class long-range AUVs ran fully autonomous patch tracking algorithms which detected phytoplankton patches and continually updated estimates of each patch center by driving adaptive patterns through the patch. Iterations of the algorithm were generated to overcome the challenges of tracking advecting and evolving patches while minimizing human involvement in vehicle control. Such fully autonomous monitoring will be necessary to perform long-term in

  16. Classification of Water Masses and Targeted Sampling of Ocean Plankton Populations by an Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Ryan, J. P.; Bellingham, J. G.; Harvey, J.; McEwen, R.; Chavez, F.; Scholin, C.

    2011-12-01

    Autonomous underwater vehicles (AUVs) are playing an increasingly active role in oceanographic surveys due to their mobility, efficiency, and growing intelligence. The Dorado AUV is equipped with a comprehensive suite of in situ sensors and ten 1.8-liter water samplers (called "gulpers"). During an October 2010 experiment in Monterey Bay, the AUV ran our autonomous peak-capture algorithm to acquire chlorophyll/backscatter peak samples from a phytoplankton bloom, allowing biologists to successfully monitor fluctuations in harmful microalgae (Psuedo-nitzschia spp.), the toxin they produce (domoic acid), and co-occurring zooplankton (invertebrate larvae and copepods) over space and time. For further investigations of the complex marine ecosystem in northern Monterey Bay, we set a more challenging goal: when the AUV flies from an upwelling shadow region (stratified water column) through an upwelling front into newly upwelled water, can it autonomously distinguish among water columns with different vertical structures and accordingly sample plankton populations on either side of, as well as within, the upwelling front? To achieve this goal, we have developed two new algorithms, one for distinguishing upwelling water columns from stratified water columns based on the vertical homogeneity of temperature, and the other for detecting an upwelling front based on the horizontal gradient of temperature. For acquiring targeted water samples, the 10 gulpers are appropriately allocated to the two distinct water columns and the front. Lockout time intervals between triggerings are set to prevent "dense triggerings". During our June 2011 experiment, the Dorado AUV flew westward from an upwelling shadow region (stratified water column) through an upwelling front, and into an upwelling water column. Three gulpers were allocated to the stratified water column, four to the front, and the remaining three to the upwelling water column. The AUV successfully detected and acquired targeted

  17. Task Assignment and Path Planning for Multiple Autonomous Underwater Vehicles Using 3D Dubins Curves (†).

    PubMed

    Cai, Wenyu; Zhang, Meiyan; Zheng, Yahong Rosa

    2017-07-11

    This paper investigates the task assignment and path planning problem for multiple AUVs in three dimensional (3D) underwater wireless sensor networks where nonholonomic motion constraints of underwater AUVs in 3D space are considered. The multi-target task assignment and path planning problem is modeled by the Multiple Traveling Sales Person (MTSP) problem and the Genetic Algorithm (GA) is used to solve the MTSP problem with Euclidean distance as the cost function and the Tour Hop Balance (THB) or Tour Length Balance (TLB) constraints as the stop criterion. The resulting tour sequences are mapped to 2D Dubins curves in the X - Y plane, and then interpolated linearly to obtain the Z coordinates. We demonstrate that the linear interpolation fails to achieve G 1 continuity in the 3D Dubins path for multiple targets. Therefore, the interpolated 3D Dubins curves are checked against the AUV dynamics constraint and the ones satisfying the constraint are accepted to finalize the 3D Dubins curve selection. Simulation results demonstrate that the integration of the 3D Dubins curve with the MTSP model is successful and effective for solving the 3D target assignment and path planning problem.

  18. Development of a three-dimensional guidance system for long-range maneuvering of a miniature autonomous underwater vehicle

    NASA Astrophysics Data System (ADS)

    Ataei, Mansour; Yousefi-Koma, Aghil

    2014-12-01

    The present paper introduces a three-dimensional guidance system developed for a miniature Autonomous Underwater Vehicle (AUV). The guidance system determines the best trajectory for the vehicle based on target behavior and vehicle capabilities. The dynamic model of this novel AUV is derived based on its special characteristics such as the horizontal posture and the independent diving mechanism. To design the guidance strategy, the main idea is to select the desired depth, presumed proportional to the horizontal distance of the AUV and the target. By connecting the two with a straight line, this strategy helps the AUV move in a trajectory sufficiently close to this line. The adjacency of the trajectory to the line leads to reasonably short travelling distances and avoids unsafe areas. Autopilots are designed using sliding mode controller. Two different engagement geometries are considered to evaluate the strategy's performance: stationary target and moving target. The simulation results show that the strategy can provide sufficiently fast and smooth trajectories in both target situations.

  19. Integration of the real-time tracking gradiometer (RTG) aboard the autonomous underwater vehicle (AUV) Morpheus

    NASA Astrophysics Data System (ADS)

    Allen, George I.; Matthews, Robert; Wynn, Michael

    2001-10-01

    In keeping with the Navy's policy to remove humans from harms way, the Autonomous Underwater Vehicle (AUV) is replacing human divers for many missions. The Advanced Marine Systems Lab at Florida Atlantic University (FAU) has developed a small, magnetically friendly, modular plastic AUV called Morpheus designed for coastal applications and especially suited for very shallow water (VSW) mine reconnaissance. Currently employed sensor technologies on AUVs have certain deficiencies and limitations when used across the wide gamut of naval targets and environments, and a strong requirement exists for a sensor or sensors to fill these niches. The Real-time Tracking Gradiometer (RTG) selected for this integration is truly such a niche sensor because its capabilities are not degraded by media interfaces or environmental conditions. It is an experimental prototype fluxgate magnetometer array developed by Quantum Magnetics for the Coastal Systems Station (CSS) and was designed to be man portable and self contained. While limited by physics in detection range, it is capable of detecting ferrous targets under the worst environmental conditions, even when the target is buried. While not having the range of sonar, the RTG does not respond to the false alarms that are indicated by sonar, and since it is capable of also providing range and bearing information, it provides an invaluable niche filling classification tool. The placing of any magnetic sensing system on a conventional AUV is a non-trivial problem. The standard AUV is designed around materials and components that were selected to maximize performance without regard to the magnetic properties of the materials used in its fabrication. To minimize the degradation of sensor performance caused by the platform, several steps must be taken. These include; the substitution of nonferrous components for ferrous, maximizing the separation between the sensor and magnetic field sources, minimizing current loops and using auxiliary

  20. A biological hierarchical model based underwater moving object detection.

    PubMed

    Shen, Jie; Fan, Tanghuai; Tang, Min; Zhang, Qian; Sun, Zhen; Huang, Fengchen

    2014-01-01

    Underwater moving object detection is the key for many underwater computer vision tasks, such as object recognizing, locating, and tracking. Considering the super ability in visual sensing of the underwater habitats, the visual mechanism of aquatic animals is generally regarded as the cue for establishing bionic models which are more adaptive to the underwater environments. However, the low accuracy rate and the absence of the prior knowledge learning limit their adaptation in underwater applications. Aiming to solve the problems originated from the inhomogeneous lumination and the unstable background, the mechanism of the visual information sensing and processing pattern from the eye of frogs are imitated to produce a hierarchical background model for detecting underwater objects. Firstly, the image is segmented into several subblocks. The intensity information is extracted for establishing background model which could roughly identify the object and the background regions. The texture feature of each pixel in the rough object region is further analyzed to generate the object contour precisely. Experimental results demonstrate that the proposed method gives a better performance. Compared to the traditional Gaussian background model, the completeness of the object detection is 97.92% with only 0.94% of the background region that is included in the detection results.

  1. Subsurface observations of white shark Carcharodon carcharias predatory behaviour using an autonomous underwater vehicle.

    PubMed

    Skomal, G B; Hoyos-Padilla, E M; Kukulya, A; Stokey, R

    2015-12-01

    In this study, an autonomous underwater vehicle (AUV) was used to test this technology as a viable tool for directly observing the behaviour of marine animals and to investigate the behaviour, habitat use and feeding ecology of white sharks Carcharodon carcharias near Guadalupe Island off the coast of Mexico. During the period 31 October to 7 November 2013, six AUV missions were conducted to track one male and three female C. carcharias, ranging in estimated total length (LT ) from 3·9 to 5·7 m, off the north-east coast of Guadalupe Island. In doing so, the AUV generated over 13 h of behavioural data for C. carcharias at depths down to 90 m. The sharks remained in the area for the duration of each mission and moved through broad depth and temperature ranges from the surface to 163·8 m depth (mean ± S.D. = 112·5 ± 40·3 m) and 7·9-27·1° C (mean ± S.D. = 12·7 ± 2·9° C), respectively. Video footage and AUV sensor data revealed that two of the C. carcharias being tracked and eight other C. carcharias in the area approached (n = 17), bumped (n = 4) and bit (n = 9) the AUV during these tracks. This study demonstrated that an AUV can be used to effectively track and observe the behaviour of a large pelagic animal, C. carcharias. In doing so, the first observations of subsurface predatory behaviour were generated for this species. At its current state of development, this technology clearly offers a new and innovative tool for tracking the fine-scale behaviour of marine animals. © 2015 The Fisheries Society of the British Isles.

  2. Operating a High Volume Plankton Sampler from a Deep Water Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Kaiser, C. L.; Billings, A.; Young, C.; Hiebert, L.; Van Dover, C. L.

    2016-02-01

    During the summer of 2015, a high volume plankton sampler was placed on the Autonomous Underwater Vehicle (AUV) Sentry as part of a cruise to investigate methane seeps. The sampler was successful in collecting over 800 larvae and 130 morphotypes. Most samples were split 2:1 or 4:1, so the total collection was substantially higher. The Sentry Precision Impeller Driven Sampler (SyPRID Sampler) was designed to mount as a "backpack" for the AUV Sentry. Sentry is able to fly the sampler at precision altitude as close as 150 cm from the seafloor and in precision patterns or locations for durations of 18 hours or more. Acoustic telemetry is used to monitor both Sentry and the samplers and to tune flight profiles or sampler operation in real time. Two independent samples can be collected per dive, allowing for comparative studies. The sampler is designed based on lessons learned from traditional tow-net systems and utilizes standard mesh net - in this case 150 micron. The sampler is impeller driven and Sentry moves at approximately 0.25m/s, resulting in little or no bow wave while maintaining an estimated flow rate of between 600 and 1000 m3/h per side. The sampler funnels plankton to a "cod end", where restriction and expansion is used to substantially reduce fluid pressure and velocity, thereby preserving the larvae in excellent condition. Valves are used to prevent contamination when not actively sampling. Substantial co-registered data is collected during the sampling including, CTD, optical backscatter, dissolved Oxygen, redox potential, and magnetics. When sampling more than 5m above bottom, multibeam sonar data can be collected. Future work will include simultaneous photography of the bottom for low-altitude sampling missions, real-time flow rate measurement, and simultaneous collection of ADCP water column data. Future work will also likely include use in the water column. The sampler is available for use on Sentry through UNOLS.

  3. A Data Link Layer in Support of Swarming of Autonomous Underwater Vehicles

    ERIC Educational Resources Information Center

    Jabba Molinares, Daladier

    2009-01-01

    Communication underwater is challenging because of the inherent characteristics of the media. First, common radio frequency (RF) signals utilized in wireless communications cannot be used under water. RF signals are attenuated in such as way that RF communication underwater is restricted to very few meters. As a result, acoustic-based…

  4. A Data Link Layer in Support of Swarming of Autonomous Underwater Vehicles

    ERIC Educational Resources Information Center

    Jabba Molinares, Daladier

    2009-01-01

    Communication underwater is challenging because of the inherent characteristics of the media. First, common radio frequency (RF) signals utilized in wireless communications cannot be used under water. RF signals are attenuated in such as way that RF communication underwater is restricted to very few meters. As a result, acoustic-based…

  5. Design of an Autonomous Underwater Vehicle to Calibrate the Europa Clipper Ice-Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Stone, W.; Siegel, V.; Kimball, P.; Richmond, K.; Flesher, C.; Hogan, B.; Lelievre, S.

    2013-12-01

    Jupiter's moon Europa has been prioritized as the target for the Europa Clipper flyby mission. A key science objective for the mission is to remotely characterize the ice shell and any subsurface water, including their heterogeneity, and the nature of surface-ice-ocean exchange. This objective is a critical component of the mission's overarching goal of assessing the habitability of Europa. The instrument targeted for addressing key aspects of this goal is an ice-penetrating radar (IPR). As a primary goal of our work, we will tightly couple airborne IPR studies of the Ross Ice Shelf by the Europa Clipper radar team with ground-truth data to be obtained from sub-glacial sonar and bio-geochemical mapping of the corresponding ice-water and water-rock interfaces using an advanced autonomous underwater vehicle (AUV). The ARTEMIS vehicle - a heavily morphed long-range, low drag variant of the highly successful 4-degree-of-freedom hovering sub-ice ENDURANCE bot -- will be deployed from a sea-ice drill hole adjacent the McMurdo Ice Shelf (MIS) and will perform three classes of missions. The first includes original exploration and high definition mapping of both the ice-water interface and the benthic interface on a length scale (approximately 10 kilometers under-ice penetration radius) that will definitively tie it to the synchronous airborne IPR over-flights. These exploration and mapping missions will be conducted at up to 10 different locations along the MIS in order to capture varying ice thickness and seawater intrusion into the ice shelf. Following initial mapping characterization, the vehicle will conduct astrobiology-relevant proximity operations using bio-assay sensors (custom-designed UV fluorescence and machine-vision-processed optical imagery) followed by point-targeted studies at regions of interest. Sample returns from the ice-water interface will be triggered autonomously using real-time-processed instrument data and onboard decision-to-collect algorithms

  6. Modeling the utility of binaural cues for underwater sound localization.

    PubMed

    Schneider, Jennifer N; Lloyd, David R; Banks, Patchouly N; Mercado, Eduardo

    2014-06-01

    The binaural cues used by terrestrial animals for sound localization in azimuth may not always suffice for accurate sound localization underwater. The purpose of this research was to examine the theoretical limits of interaural timing and level differences available underwater using computational and physical models. A paired-hydrophone system was used to record sounds transmitted underwater and recordings were analyzed using neural networks calibrated to reflect the auditory capabilities of terrestrial mammals. Estimates of source direction based on temporal differences were most accurate for frequencies between 0.5 and 1.75 kHz, with greater resolution toward the midline (2°), and lower resolution toward the periphery (9°). Level cues also changed systematically with source azimuth, even at lower frequencies than expected from theoretical calculations, suggesting that binaural mechanical coupling (e.g., through bone conduction) might, in principle, facilitate underwater sound localization. Overall, the relatively limited ability of the model to estimate source position using temporal and level difference cues underwater suggests that animals such as whales may use additional cues to accurately localize conspecifics and predators at long distances. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Dynamic modeling and motion simulation for a winged hybrid-driven underwater glider

    NASA Astrophysics Data System (ADS)

    Wang, Shu-Xin; Sun, Xiu-Jun; Wang, Yan-Hui; Wu, Jian-Guo; Wang, Xiao-Ming

    2011-03-01

    PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV (autonomous underwater vehicle). It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.

  8. Under-Ice Science in the Polar Regions with Autonomous Underwater Vehicles

    NASA Astrophysics Data System (ADS)

    Kunz, C.; Murphy, C.; Singh, H.; Das, S. B.; Jackson, R. H.; Kukulya, A.; Littlefield, R.; Maksym, T. L.; Plueddemann, A. J.; Sohn, R. A.; Straneo, F.; Wilkinson, J.

    2012-12-01

    Developments in autonomous underwater vehicle (AUV) technology over the last decade have enabled scientists to study areas of the ocean at high latitude that were previously unapproachable. In particular, advances in acoustic communications, robotic autonomy and navigation, and compact sensor technology allow AUVs to work in close proximity to sea ice, glacial fronts, and the sea floor under multi-year pack ice. We describe the technology that enabled several expeditions to both polar regions that have used Seabed-class AUVs as the primary platform for making scientific measurements. We also describe current and upcoming missions using the smaller Seabed-100 and REMUS-100 AUVs for shallow-water work near glacial fronts. Several problems must be solved in order to successfully use robots under ice. Acoustic communications must be robust enough for operators on the surface to inform the AUV of changing conditions so that the vehicle can safely return to open water on the surface - during the AGAVE and IceBell expeditions, we experienced sea ice drift rates of tens of centimeters per second, and moving ice floes that constrained the availability of open water. AUV navigation must be flexible enough for the robot to switch reference frames during a mission depending on the conditions and on the scientific objective. During a single deployment during the IceBell expedition, it was typical for the robot to switch from ship-relative (using acoustic transponders), to ice-relative (using a doppler velocity log), to ice-relative (using a distinct set of acoustic transponders), and back again; an AUV may also need to navigate relative to the sea floor (as during the AGAVE expedition). Making ice-relative measurements also requires taking ice floe rotation into account, and on-board navigation relative to a rotating frame may be necessary. Finally, specialized scenarios such as when navigating near a glacial front require navigation relative to vertical, rather than horizontal

  9. Robust Huber-Based Iterated Divided Difference Filtering with Application to Cooperative Localization of Autonomous Underwater Vehicles

    PubMed Central

    Gao, Wei; Liu, Yalong; Xu, Bo

    2014-01-01

    A new algorithm called Huber-based iterated divided difference filtering (HIDDF) is derived and applied to cooperative localization of autonomous underwater vehicles (AUVs) supported by a single surface leader. The position states are estimated using acoustic range measurements relative to the leader, in which some disadvantages such as weak observability, large initial error and contaminated measurements with outliers are inherent. By integrating both merits of iterated divided difference filtering (IDDF) and Huber's M-estimation methodology, the new filtering method could not only achieve more accurate estimation and faster convergence contrast to standard divided difference filtering (DDF) in conditions of weak observability and large initial error, but also exhibit robustness with respect to outlier measurements, for which the standard IDDF would exhibit severe degradation in estimation accuracy. The correctness as well as validity of the algorithm is demonstrated through experiment results. PMID:25536004

  10. Robust Huber-based iterated divided difference filtering with application to cooperative localization of autonomous underwater vehicles.

    PubMed

    Gao, Wei; Liu, Yalong; Xu, Bo

    2014-12-19

    A new algorithm called Huber-based iterated divided difference filtering (HIDDF) is derived and applied to cooperative localization of autonomous underwater vehicles (AUVs) supported by a single surface leader. The position states are estimated using acoustic range measurements relative to the leader, in which some disadvantages such as weak observability, large initial error and contaminated measurements with outliers are inherent. By integrating both merits of iterated divided difference filtering (IDDF) and Huber's M-estimation methodology, the new filtering method could not only achieve more accurate estimation and faster convergence contrast to standard divided difference filtering (DDF) in conditions of weak observability and large initial error, but also exhibit robustness with respect to outlier measurements, for which the standard IDDF would exhibit severe degradation in estimation accuracy. The correctness as well as validity of the algorithm is demonstrated through experiment results.

  11. Autonomous Underwater Vehicle(AUV) and Towed Vehicle Technologies for Under-Ice Hydrothermal Vent Studies at the Gakkel Ridge

    NASA Astrophysics Data System (ADS)

    Singh, H.; Akin, D.; Reves-Sohn, R.; Humphris, S.; Shank, T.; Edmonds, H.

    2006-12-01

    The extreme polar environment presents a unique challenge to the use of the otherwise mature oceanographic technologies associated with Autonomous Underwater Vehicles (AUVs), Remotely Operated Vehicles (ROVs) and towed vehicles. For deep water mapping and sampling applications, ice cover in the arctic is a formidable obstacle. In pursuing our goals to locate, map and sample hydrothermal vents on the Gakkel Ridge, we have built and plan to deploy two AUVs named JAGUAR and PUMA and a towed sampling sled with hydraulically actuated sampling chambers. Our methodologies for working with AUVs in the Arctic differ significantly from standard blue-water operations. Specifically, we have focused on, deploying and calibrating acoustic transponders with the limited mobility imposed by multi-year ice; a far more robust system architecture for dealing with component failures underwater; an autonomous manipulation system on the AUV for capturing sessile biological organisms and geological samples; and a low bandwidth acoustic tether for vehicle status, navigation and mission redirection. Our sampling sled was designed with the premise that the limited mobility associated with working in ice will at best provide us with a few, short opportunities to image and sample on a hydrothermal vent site. To this end our sled is equipped with a suite of imaging and chemical sensors as well as devices for quickly obtaining multiple samples of both sessile and motile biological organisms. We plan to deploy these new technologies during the International Polar Year in 2007 as part of a collaborative international effort to characterize the biological and geological characteristics of hydrothermal venting on the ultra-slow spreading Gakkel Ridge in the eastern Arctic basin.

  12. Development of a Semi-Autonomous Underwater Vehicle for Intervention Missions

    DTIC Science & Technology

    2002-06-30

    the Ansaldo manipulator runs off the VME bus system using VxWorks and Matlab with Simulink. Development in the “rapid prototyping, graphic software...has been the central point in enhancing the complex, underwater dynamic actions and reactions. The manipulator control codes have been developed to...ODIN vehicle. Once both the manipulation and hovering control codes are considered sufficient, a small, 2-dof manipulator will be added to ODIN for

  13. Underwater Acoustic Networks: An Acoustic Propagation Model for Simulation of Underwater Acoustic Networks

    DTIC Science & Technology

    2005-12-01

    Applications Underwater sound propagation has been used either for military applications like sonar, mine fields, voice communication , or civilian use such...as hydrographic surveys, oceanographic studies, and marine life research. Wireless communications to this date are a common part in our daily life...and the term wireless is usually associated with over the air communications and not related to underwater communications . Underwater networks may

  14. First observations of teleseismic P-waves with autonomous underwater robots: towards future global network of mobile seismometers

    NASA Astrophysics Data System (ADS)

    Sukhovich, Alexei; Nolet, Guust; Hello, Yann; Simons, Frederik; Bonnieux, Sébastien

    2013-04-01

    We report here the first successful observations of underwater acoustic signals generated by teleseismic P-waves recorded by autonomous robots MERMAID (short for Mobile Earthquake Recording in Marine Areas by Independent Divers). During 2011-2012 we have conducted three test campaigns for a total duration of about 8 weeks in the Ligurian Sea which have allowed us to record nine teleseismic events (distance more than 60 degree) of magnitudes higher than 6 and one closer event (distance 23 degree) of magnitude 5.5. Our results indicate that no simple relation exists between the magnitude of the source event and the signal-to-noise ratio (SNR) of the corresponding acoustic signals. Other factors, such as fault orientation and meteorological conditions, play an important role in the detectability of the seismic events. We also show examples of the events recorded during these test runs and how their frequency characteristics allow them to be recognized automatically by an algorithm based on the wavelet transform. We shall also report on more recent results obtained during the first fully autonomous run (currently ongoing) of the final MERMAID design in the Mediterranean Sea.

  15. Two-stage underwater image restoration based on a physical model

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Qi, Lin; Dong, Junyu; Fan, Hao; Chen, Xingnan; Yu, Hui

    2017-02-01

    Underwater images are blurred due to light scattering and absorption. Image restoration is therefore important in many underwater research and practical tasks. In this paper, we propose an effective two-stage method to restore underwater scene images. Based on an underwater light propagation model, we first remove backscatter by fitting a binary quadratic function. Then we eliminate the forward scattering and non-uniform lighting attenuation using blue-green dark channel prior. The proposed method requires no additional calibration and we show its effectiveness and robustness by restoring images captured under various underwater scenes.

  16. Feature Modeling in Underwater Environments Using Sparse Linear Combinations

    DTIC Science & Technology

    2010-01-01

    waters . Optics Express, 16(13), 2008. 2, 3 [9] J. Jaflfe. Monte carlo modeling of underwate-image forma- tion: Validity of the linear and small-angle... turbid water , etc), we would like to determine if these two images contain the same (or similar) object(s). One approach is as follows: 1. Detect...nearest neighbor methods on extracted feature descriptors This methodology works well for clean, out-of- water images, however, when imaging underwater

  17. Underwater drag-reducing effect of superhydrophobic submarine model.

    PubMed

    Zhang, Songsong; Ouyang, Xiao; Li, Jie; Gao, Shan; Han, Shihui; Liu, Lianhe; Wei, Hao

    2015-01-01

    To address the debates on whether superhydrophobic coatings can reduce fluid drag for underwater motions, we have achieved an underwater drag-reducing effect of large superhydrophobic submarine models with a feature size of 3.5 cm × 3.7 cm × 33.0 cm through sailing experiments of submarine models, modified with and without superhydrophobic surface under similar power supply and experimental conditions. The drag reduction rate reached as high as 15%. The fabrication of superhydrophobic coatings on a large area of submarine model surfaces was realized by immobilizing hydrophobic copper particles onto a precross-linked polydimethylsiloxane (PDMS) surface. The pre-cross-linking time was optimized at 20 min to obtain good superhydrophobicity for the underwater drag reduction effect by investigating the effect of pre-cross-linking on surface wettability and water adhesive property. We do believe that superhydrophobic coatings may provide a promising application in the field of drag-reducing of vehicle motions on or under the water surface.

  18. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications

    PubMed Central

    Cañete, Francisco J.; López-Fernández, Jesús; García-Corrales, Celia; Sánchez, Antonio; Robles, Encarnación; Rodrigo, Francisco J.; Paris, José F.

    2016-01-01

    Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression. PMID:26907281

  19. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications.

    PubMed

    Cañete, Francisco J; López-Fernández, Jesús; García-Corrales, Celia; Sánchez, Antonio; Robles, Encarnación; Rodrigo, Francisco J; Paris, José F

    2016-02-19

    Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression.

  20. Characteristic Morphology, Backscatter, and Sub-seafloor Structures of Cold-Vents on the Northern Cascadia Margin from High-Resolution Autonomous Underwater Vehicle Data

    NASA Astrophysics Data System (ADS)

    Francolin, Camila Clemente

    In this thesis seafloor cold vents are examined using autonomous underwater vehicle (AUV) and remotely operated vehicle (ROV) data on the Northern Cascadia margin. These data were collected in a 2009 joint cruise between the Monterey Bay Aquarium Research Institute (MBARI) and Natural Resources Canada (NRCan). High-resolution bathymetry data, acoustic reflectivity (backscatter) data, and 3.5 kHz sub bottom profiler data were examined for cold-vent-related features that include pockmarks, chemosynthetic biological communities (CBC), and authigenic carbonate. Additionally subsequent ROV observations, sediments from push cores and seafloor video/photos were used to ground truth AUV data. Numerous prolific venting sites were examined in detail and a model for the evolution of venting was generated. Vents are categorized as juvenile, intermediate, or mature depending on the presence and or absence of cold-vent-features. High near-surface reflection amplitudes are coincident with an anomalous area of seafloor backscatter. In June of 2012, NEPTUNE (North East Pacific Time-series Underwater Networked Experiment) collected a near-surface push core with their ROV ROPOS (Remotely Operated Platform for Ocean Sciences) in the high reflective area. The retrieved core showed stacked turbidites in the top 0.5 meters of the sediment column. Closely spaced high-velocity turbidite sands are highly reflective and inhibit acoustic penetration to depth. The presence of high-density, high-velocity sands in the near surface is linked to steady ocean bottom currents. These bottom currents progress northeast to southwest over the study area and differentially erode the surface sediments by removing muds and leaving heavy sands over the exposed area.

  1. A Deep Sea Docking Station for ODYSSEY Class Autonomous Underwater Vehicles

    DTIC Science & Technology

    2007-11-02

    autonomous midwater missions. The Station is integrated into the main tension member of a deep sea mooring system. A large subsea flotation sphere supports...radio frequency communications. Primary subsystems of the Docking Station described in this report include a dock controller with multi- sensor support

  2. The Next Milestone: A Multicarrier Acoustic MODEM with Channel- and Network-Adaptivity for Underwater Autonomous Distributed Systems

    DTIC Science & Technology

    2010-09-30

    We have three objectives in this project. 1. Make OFDM work underwater. The success of multicarrier modulation in the form of orthogonal...frequency-division- modulation (OFDM) in radio channels illuminates a clear path one could take towards high-rate underwater acoustic communications...However, earlier work on the application of OFDM in underwater has only had limited success. We aim to make OFDM work in underwater environments. 2

  3. Passive Bottom Loss Estimation Using Compact Arrays and Autonomous Underwater Vehicles

    DTIC Science & Technology

    2015-09-30

    DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Passive bottom loss estimation using compact arrays and autonomous...source of error being the low accuracy in bottom- loss estimation [Ferla, 2002]. While the classical approach to acquiring the bottom reflection...frequency range indicated above, the poor angular resolution of the short arrays required in AUV deployment causes an underestimation of the loss

  4. Advancing Underwater Acoustic Communication for Autonomous Distributed Networks via Sparse Channel Sensing, Coding, and Navigation Support

    DTIC Science & Technology

    2013-09-30

    2013. 10. J. Song, S. Gupta, J. Hare, and S. Zhou, ``Adaptive cleaning of oil spills by autonomous vehicles under partial information,’’ in Proc. of... BP ) decoding algorithm. In this work, we propose a new iterative decoding algorithm for both binary and nonbinary fields. The basic form of our...proposed algorithm considers both degree-1 and degree-2 check nodes (instead of only degree-1 check nodes as in the original BP decoding scheme), and has

  5. Integrated synoptic surveys using an autonomous underwater vehicle and manned boats

    USGS Publications Warehouse

    Jackson, P. Ryan

    2013-01-01

    Traditional surface-water surveys are being combined with autonomous technology to produce integrated surveys of bathymetry, water quality, and velocity in inland lakes and reservoirs. This new technology provides valuable, high-resolution, integrated data that allow a systems-based approach to understanding common environmental problems. This fact sheet presents several example applications of integrated surveys within inland lakes and coastal Lake Michigan and Lake Erie.

  6. The Use of Autonomous Underwater Vehicles for Deep-Reef Discovery and Benthic Characterization To Aid Conservation and Management

    NASA Astrophysics Data System (ADS)

    Rissolo, D.; Reed, J. K.; Auster, P. J.; Sherrell, A.; Dessner, M.; Purcell, M.; Packard, G.

    2012-12-01

    Recent exploratory research along the Atlantic coast of the US has demonstrated the utility of dual autonomous underwater vehicle (AUV) systems for side-scan surveys, multibeam mapping, and photo-imaging of deep-water habitat and octocoral gardens. The potential of the REMUS 6000 AUVs was demonstrated by mapping high-relief coral mounds in the Straits of Florida in the strong currents of the Gulf Stream, and the submarine canyons and seamounts off the Northeastern US coast. The key to protecting these slow-growing deep coral reefs and critical hard-bottom habitat is the ability to efficiently discover and map their locations, characterize their structure, and assess their condition. Data from these deepwater AUV surveys were used to inform the regional fishery management councils and NOAA NMFS for the management and potential protection of these vulnerable habitats. These projects were realized though the collaborative efforts of the Waitt Institute, Woods Hole Oceanographic Institution, Harbor Branch Oceanographic Institute, NOAA National Marine Fisheries Service, the Natural Resource Defense Council, and the University of Connecticut.

  7. Plankton in Monterey Bay: Optimization of optical sensor data from autonomous underwater vehicles with applications in plankton community composition

    NASA Astrophysics Data System (ADS)

    Wyse, Diane E.

    Autonomous underwater vehicles (AUVs) equipped with oceanographic sensors demonstrate the capability to describe plankton communities in the marine environment. The vehicles collect data from the surface through the mixed layer for a variety of oceanographic parameters. The Monterey Bay Aquarium Research Institute operates the Dorado upper-water-column AUV. The Dorado AUV collects data for 32 size-classes, from 1.25 to 250 mum, using a laser in-situ scattering and transmissometry (LISST-100X) instrument. The objective of this study is to analyze data from AUVs and laboratory work to inform sampling methods with applications in targeting specific classes of plankton, particularly harmful algal bloom species. The results of this study show that specific combinations of LISST-100X size class channels can be combined to reconstruct fluorescence data. This project includes laboratory tests with monocultures of phytoplankton on both a backscattering sensor that detects chlorophyll at 695 nm and on the forward scattering LISST-100X sensor. The results show a linear relationship between backscattered chlorophyll concentration and cell density for four monocultures of phytoplankton. The forward scattering lab experiments show distinct organism signatures for three genera of phytoplankton tested as monocultures.

  8. Underwater striling engine design with modified one-dimensional model

    NASA Astrophysics Data System (ADS)

    Li, Daijin; Qin, Kan; Luo, Kai

    2015-05-01

    Stirling engines are regarded as an efficient and promising power system for underwater devices. Currently, many researches on one-dimensional model is used to evaluate thermodynamic performance of Stirling engine, but in which there are still some aspects which cannot be modeled with proper mathematical models such as mechanical loss or auxiliary power. In this paper, a four-cylinder double-acting Stirling engine for Unmanned Underwater Vehicles (UUVs) is discussed. And a one-dimensional model incorporated with empirical equations of mechanical loss and auxiliary power obtained from experiments is derived while referring to the Stirling engine computer model of National Aeronautics and Space Administration (NASA). The P-40 Stirling engine with sufficient testing results from NASA is utilized to validate the accuracy of this one-dimensional model. It shows that the maximum error of output power of theoretical analysis results is less than 18% over testing results, and the maximum error of input power is no more than 9%. Finally, a Stirling engine for UUVs is designed with Schmidt analysis method and the modified one-dimensional model, and the results indicate this designed engine is capable of showing desired output power.

  9. Underwater striling engine design with modified one-dimensional model

    NASA Astrophysics Data System (ADS)

    Li, Daijin; Qin, Kan; Luo, Kai

    2015-09-01

    Stirling engines are regarded as an efficient and promising power system for underwater devices. Currently, many researches on one-dimensional model is used to evaluate thermodynamic performance of Stirling engine, but in which there are still some aspects which cannot be modeled with proper mathematical models such as mechanical loss or auxiliary power. In this paper, a four-cylinder double-acting Stirling engine for Unmanned Underwater Vehicles (UUVs) is discussed. And a one-dimensional model incorporated with empirical equations of mechanical loss and auxiliary power obtained from experiments is derived while referring to the Stirling engine computer model of National Aeronautics and Space Administration (NASA). The P-40 Stirling engine with sufficient testing results from NASA is utilized to validate the accuracy of this one-dimensional model. It shows that the maximum error of output power of theoretical analysis results is less than 18% over testing results, and the maximum error of input power is no more than 9%. Finally, a Stirling engine for UUVs is designed with Schmidt analysis method and the modified one-dimensional model, and the results indicate this designed engine is capable of showing desired output power.

  10. Computational Hydrodynamics and Control Modeling for Autonomous Underwater Vehicles

    DTIC Science & Technology

    2001-09-30

    unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 body was modified so that simulations could be conducted of the Seahorse ...and outboard of the body. Turbulent viscous solutions were obtained for this body at angle-of- attacks ranging from zero to fifteen degrees. The...Reynolds number based on the length of the hull was about 14 million. In addition to the steady angle of attack cases, a set of prescribed motion cases

  11. Development of An Autonomous Underwater Glider for Observing Physical Ocean Parameters in Indonesian Seas

    NASA Astrophysics Data System (ADS)

    Ajie Linarka, Utoyo; Riyanto Trilaksono, Bambang; Sagala, M. Faisal; Hidayat, Egi; Sopaheluwakan, Ardhasena; Rizal, Jose; Heriyanto, Eko; Amsal Harapan, Ferdika; Eka Syahputra Makmur, Erwin

    2017-04-01

    Conducting a sustained monitoring and surveying of physical ocean parameters for research or operational purposes using moorings and ships would require high cost. Development of an inexpensive instrument capable to perform such tasks not only could reduce cost and risks but also increase cruising range and depth. For that reason, a prototype of underwater glider was developed, named "GaneshBlue". GaneshBlue works based on gliding principles which utilizes pitch angle and buoyancy control for moving. For one gliding movement, GaneshBlue passed through 5 phases of surface, descent, transition, ascent and back to surface. The glider is equipped with basic navigation system and remote control, programmable survey planning, temperature and salinity sampling instruments, lithium batteries for power supply, and information processing software. A field test at the shallow water showed that GaneshBule has successfully demonstrated gliding and surfacing movements with surge motion speed reaching 20 cm s-1and 20 m in depths. During the field test the glider was also equipped with three instruments, i.e. Inertial Measurement Unit (IMU) to estimate glider's speed and orientation; MiniCT to acquire temperature and conductivity data; and Altisounder to determine its distance to sea surface and to seabed. In general, all the instruments performed well but filter algorithm needs to be implemented on data collection procedure to remove data outliers.

  12. GRBNeT - A prototype for an autonomous underwater neutrino detector

    NASA Astrophysics Data System (ADS)

    Pikounis, K.; Markou, C.; Anassontzis, E. G.; Androulakis, G.; Bagatelas, C.; Balasi, K.; Belias, A.; Damianos, P.; Drakopoulou, E.; Kappos, E.; Manolopoulos, K.; Rapidis, P.; Tzamariudaki, E.; Voulgaris, G.

    2016-04-01

    GRBNeT is a project aiming at the detection of ultra-high energy neutrinos, for example neutrinos originating from Gamma Ray Bursts. The goal is to design, construct and deploy a prototype unit of an autonomous (data/energy-wise) neutrino detector. Being autonomous is crucial since for the detection of ultra-high energy neutrinos a very large volume of water is required. Large scale facilities such as IceCube and KM3NeT are designed to be more sensitive to galactic and diffuse flux neutrinos rather than extragalactic ultra-high energy neutrinos. However, their sensitivity to such neutrinos could be increased by placing around and at larger distances detectors such as the one of the GRBNeT project. This extension would increase the instrumented volume of neutrino telescopes to several cubic kilometres. In addition to that, as no cable connection to the shore is required, GRBNeT detection units cost significantly less than regular detection units and can become a cost effective extension of large scale facilities. For the GRBNeT prototype unit ultra low power electronics have been developed. The response to high energy neutrinos from GRBs and to the atmospheric muon background has been simulated.

  13. Multisensor Modeling Underwater with Uncertain Information

    DTIC Science & Technology

    1988-07-01

    normal human eye is limited to a narrow, forward-looking cone. Optical illusions further illustrate the power of such models in shaping our human...perception, (tor examp!e, see Co,’nsw’’et. 1970: Marr. 1982). As Winston [19841 puts it, image understanding ma, be a form of "controlled hallucination ." so

  14. Model-based restoration of underwater spectral images captured with narrowband filters.

    PubMed

    Guo, Yilu; Song, Hong; Liu, Hongbo; Wei, He; Yang, Ping; Zhan, Shuyue; Wang, Hangzhou; Huang, Hui; Liao, Ningfang; Mu, Quanquan; Leng, Jianxing; Yang, Wenjing

    2016-06-13

    Underwater spectral imaging is a promising method for mapping, classification and health monitoring of coral reefs and seafloor inhabitants. However, the spectrum of light is distorted during the underwater imaging process due to wavelength-dependent attenuation by the water. This paper presents a model-based method that accurately restores brightness of underwater spectral images captured with narrowband filters. A model is built for narrowband underwater spectral imaging. The model structure is derived from physical principles, representing the absorption, scattering and refraction by water and the optical properties of narrowband filters, lenses and image sensors. The model coefficients are calibrated based on spectral images captured underwater and in air. With the imaging model available, energy loss due to water attenuation is restored for images captured at different underwater distances. An experimental setup is built and experiments are carried out to verify the proposed method. Underwater images captured within an underwater distance of 260 cm are restored and compared with those in air. Results show that the relative restoration error is 3.58% on average for the test images, thus proving the accuracy of the proposed method.

  15. Acquiring Peak Samples from Phytoplankton Thin Layers and Intermediate Nepheloid Layers by an Autonomous Underwater Vehicle with Adaptive Triggering

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; McEwen, R.; Ryan, J. P.; Bellingham, J. G.; Harvey, J.; Vrijenhoek, R.

    2010-12-01

    Phytoplankton thin layers (PTLs) affect many fundamental aspects of coastal ocean ecology including primary productivity, development of harmful algal blooms (HABs) and the survival and growth of zooplankton and fish larvae. Intermediate nepheloid layers (INLs) that contain suspended particulate matter transported from the bottom boundary layer of continental shelves and slopes also affect biogeochemistry and ecology of ocean margins. To better understand the impacts of these types of layers, we have developed an adaptive sampling method for an autonomous underwater vehicle (AUV) to detect a layer (adjusting detection parameters in situ), acquire water samples from peaks in the layer, and acquire control samples outside the layer. We have used the method in a number of field experiments with the AUV Dorado, which is equipped with ten water samplers (called "gulpers"). In real time, the algorithm tracks background levels of fluorescence and optical backscatter and the peaks' baseline to ensure that detection is tuned to the ambient conditions. The algorithm cross-checks fluorescence and backscatter signals to differentiate PTLs from INLs. To capture peak water samples with minimal delay, the algorithm exploits the AUV's sawtooth (i.e., yo-yo) trajectory: the vehicle crosses the detected layer twice in one yo-yo cycle. At the first crossing, it detects the layer's peak and saves its signal height. Sampling is triggered at the second crossing when the signal reaches the saved peak height plus meeting additional timing and depth conditions. The algorithm is also capable of triggering gulpers to acquire control samples outside the layer for comparison with ambient water. The sequence of peak and control samples can be set based on need. In recent AUV Dorado missions, the algorithm triggered the gulpers to acquire peak and control samples from INLs and PTLs in Monterey Bay. Zooplankton analysis of some peak samples showed very high concentrations of mussel and barnacle

  16. Postcaldera volcanism and hydrothermal activity revealed by autonomous underwater vehicle surveys in Myojin Knoll caldera, Izu-Ogasawara arc

    NASA Astrophysics Data System (ADS)

    Honsho, Chie; Ura, Tamaki; Kim, Kangsoo; Asada, Akira

    2016-06-01

    Myojin Knoll caldera, one of the submarine silicic calderas lying on the volcanic front of the northern Izu-Ogasawara arc, has attracted increasing attention since the discovery of a large hydrothermal field called the Sunrise deposit. Although numerous submersible surveys have been conducted in Myojin Knoll caldera, they have not sufficiently explored areas to produce a complete picture of the caldera and understand the origin of the Sunrise deposit. We conducted comprehensive deep-sea surveys using an autonomous underwater vehicle and obtained high-resolution bathymetric and magnetic data and sonar images from ~70% of the caldera. The detailed bathymetric map revealed that faulting and magma eruptions, possibly associated with an inflation-deflation cycle of the magma reservoir during postcaldera volcanism, had generally occurred in the caldera wall. The main dome of the central cone was covered with lava flows and exhibits exogenous growth, which is unusual for rhyolitic domes. The magnetization distribution in the central cone indicates preferential magma intrusion along a NW-SE direction. It is presumed that magma migrated along this direction and formed a rhyolite dome at the foot of the southeastern caldera wall, where the Sunrise deposit occurs. The Sunrise deposit is composed mainly of three ridges extending in slope directions and covers ~400 × ~400 m. Magnetization reduction in the deposit area is small, indicating that the alteration zone beneath the Sunrise deposit is slanting rather than vertical. It is presumed that several slanting and near-vertical volcanic vents serve as pathways of hydrothermal fluid in Myojin Knoll caldera.

  17. Altered niche of an ecologically significant urchin species, Centrostephanus rodgersii, in its extended range revealed using an Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Perkins, Nicholas R.; Hill, Nicole A.; Foster, Scott D.; Barrett, Neville S.

    2015-03-01

    Poleward range shifts of species as a result of global climate change are being increasingly documented. As species extend into new ranges their ecological impacts and the niches that they occupy may be unpredictable. We use benthic imagery obtained from the broad-scale deployment of an Autonomous Underwater Vehicle (AUV) to quantify the depth distribution of barrens habitat formed by a recent range extension of the sea urchin species, Centrostephanus rodgersii, a known ecosystem engineer. AUV transects covering similar depths from both the historical range of New South Wales, Australia, and from the range extension area of the east coast of Tasmania were examined for the presence of barrens. We find that C. rodgersii occupies a different realised niche in its extended range, with barrens habitat occurring significantly deeper in Tasmanian waters (16-58 m) compared to NSW waters (7-27 m). The expansion of barrens habitat has devastating impacts on biodiversity, with flow-on effects to ecosystem services and local fisheries, and in Tasmania this threat extends to deeper, invertebrate-dominated habitats. This finding has important management implications, in particular the need to incorporate deeper reef systems into planning, with increased barrens expected under future climate change predictions. One conservation management approach is the use of no-take Marine Protected Areas (MPAs) to prevent barren establishment in representative habitats by rebuilding viable populations of urchin predators. We also examine the correlation between MPA status and the occurrence of barrens within a small, no-take Tasmanian reserve and adjacent control sites. We find that there is suggestive, but inconclusive, evidence for fewer barrens in the MPA (p = 0.07). Our study highlights the utility of a novel technology for conducting large-scale benthic surveys and monitoring the impacts of range extending species.

  18. Model task for the dynamics of an underwater two-legged walker

    NASA Technical Reports Server (NTRS)

    Beletskiy, V. V.; Golubkov, V. V.; Stepanova, Y. A.

    1979-01-01

    A model task of two-legged underwater walking was examined. Characteristics of the walking were established. The underwater walking device is a substantial sphere, which moves on dual-member legs. The dynamics of the device were investigated with the calculation of the buoyancy of Archimedes, and the force of hydrodynamic resistance.

  19. AURP: An AUV-Aided Underwater Routing Protocol for Underwater Acoustic Sensor Networks

    PubMed Central

    Yoon, Seokhoon; Azad, Abul K.; Oh, Hoon; Kim, Sunghwan

    2012-01-01

    Deploying a multi-hop underwater acoustic sensor network (UASN) in a large area brings about new challenges in reliable data transmissions and survivability of network due to the limited underwater communication range/bandwidth and the limited energy of underwater sensor nodes. In order to address those challenges and achieve the objectives of maximization of data delivery ratio and minimization of energy consumption of underwater sensor nodes, this paper proposes a new underwater routing scheme, namely AURP (AUV-aided underwater routing protocol), which uses not only heterogeneous acoustic communication channels but also controlled mobility of multiple autonomous underwater vehicles (AUVs). In AURP, the total data transmissions are minimized by using AUVs as relay nodes, which collect sensed data from gateway nodes and then forward to the sink. Moreover, controlled mobility of AUVs makes it possible to apply a short-range high data rate underwater channel for transmissions of a large amount of data. To the best to our knowledge, this work is the first attempt to employ multiple AUVs as relay nodes in a multi-hop UASN to improve the network performance in terms of data delivery ratio and energy consumption. Simulations, which are incorporated with a realistic underwater acoustic communication channel model, are carried out to evaluate the performance of the proposed scheme, and the results indicate that a high delivery ratio and low energy consumption can be achieved. PMID:22438740

  20. Autonomous environment modeling by a mobile robot

    NASA Astrophysics Data System (ADS)

    Moutarlier, Philippe

    1991-02-01

    Internal geometric representation of the environment is considered. The autonomy of a mobile robot partly relies on its ability to build a reliable representation of its environment. On the other hand, an autonomous environment building process requires that model be adapted to plan motions and perception actions. Therefore, the modeling process must be a reversible interface between perception motion devices and the model itself. Several kinds of models are necessary in order to achieve an autonomous process. Sensors give stochastic information on the surface, navigation needs free-space representation, and perception planning requires aspect graphs. The functions of stochastic surface modeling, free space representation, and topological graph computing are presented through the integrated geometric model builder called 'Yaka.' Since all environment data uncertainties are correlated together through the robot location inaccuracy, classical filtering methods are inadequate. A method of computing a linear variance estimator, that is adapted to the problem, is proposed. This general formalism is validated by a large number of experimentation wherein the robot incrementally builds a surfacic representation of its environment. Free space cannot be deduced directly, at each step, from the surfacic data provided by the sensors. Innacuracies on object surfaces and uncertainties on the visibility of objects by the sensor as well as the possible motion of objects must all be taken into account for building the free space incrementally. Then, motion and perception planning for autonomous environment modeling are achieved using this free space model and topological location and aspect graphs.

  1. A Microcomputer-Based Controller for an Autonomous Underwater Vehicle (AUV)

    DTIC Science & Technology

    1990-03-01

    possible dynamic situations. In the case of the AUV, a model based on the United States Navy’s Swimmer Delivery Vehicle is used. This model is...mul(Matrix MI, int rl, int cl, Matrix M2, imt r2, int c2, Matrix M3); void control8( double *mstate, double *inputs, double ordereddepth, double...12 states depicted in Table 2. of this thesis using the dynamic equations of motion modeled after the U.S. Navy’s Swimmer Delivery Vehicle. The

  2. Automated Detection and Classification in High-Resolution Sonar Imagery for Autonomous Underwater Vehicle Operations

    DTIC Science & Technology

    2008-12-01

    Szymczak , W. Guo and J.C.W. Rogers, Mine detection using variational methods for image enhancement and feature extraction, Proc. SPIE 3392, 286-296 (1998...12. W.G. Szymczak and W. Guo, Mine detection using model-trained multi-resolution neural networks and variational methods, Proc. SPIE 3710,559-569

  3. 3D photo mosaicing of Tagiri shallow vent field by an autonomous underwater vehicle(2nd report) - Wide area visual mapping through multiple dives -

    NASA Astrophysics Data System (ADS)

    Maki, Toshihiro; Kondo, Hayato; Ura, Tamaki; Sakamaki, Takashi; Mizushima, Hayato; Yanagisawa, Masao

    The authors have proposed an innovative method to navigate an autonomous underwater vehicle (AUV) for visual mapping of seafloor with high positioning accuracy without using any vision-based matching. The proposed method was implemented in the AUV Tri-Dog 1 and sea experiments were carried out at Tagiri vent field, Kagoshima bay in Japan (Maki et al., 2008). Based on the success of the experiments, a series of dives was carried out at the same place. The AUV Tri-Dog 1 succeeded in 12 fully autonomous dives with a total duration of 29 hours. The vehicle took 9,288 pictures of the seafloor, keeping the altitude of 1.2 m with a surge speed of 0.08 m/s. A photomosaic of the seafloor was created by mapping 7,289 pictures based on the real-time estimates of the AUV state, without any pictorial correlation. The distributions of detailed features such as tube-worm colonies and bacteria mats are clearly shown. The photomosaic covers around 3,000 square meters. To the knowledge of the authors, this is one of the largest underwater photomosaic ever reported. The mapping accuracy was estimated to be 0.3 to 0.8 m based on the comparison of the photomosaic between dives.

  4. Modelling distribution of marine benthos from hydroacoustics and underwater video

    NASA Astrophysics Data System (ADS)

    Holmes, K. W.; Van Niel, K. P.; Radford, B.; Kendrick, G. A.; Grove, S. L.

    2008-08-01

    Broad-scale mapping of marine benthos is required for marine resource management and conservation. This study combines textural derivatives based on bathymetry from multibeam hydroacoustics with underwater video observations to model and map sessile biota between 10- and 60-m water depth over 35 km 2 in Point Addis Marine National Park (MNP), Vic., Australia. Classification tree models and maps were developed for macroalgae (all types, mixed red algae, Ecklonia, and rhodoliths) and sessile invertebrates (all types, sponges, and ascidians). Model accuracy was tested on 25% of the video observation dataset reserved from modelling. Models fit well for most macroalgae categories (correct classification rates of 67-84%), but are not as good for sessile invertebrate classes (correct classification rates of 57-62%). The poor fit of the sessile invertebrate models may be the combined result of grouping organisms with different environmental requirements and the effect of false absences recorded during video interpretation due to poor image quality. Probability maps, binary single-class maps, and multi-class maps supply spatially explicit, detailed information on the distribution of sessile benthic biota within the MNP and provide information at a landscape-scale for ecological investigations and marine management.

  5. Integrated synoptic surveys of the hydrodynamics and water-quality distributions in two Lake Michigan rivermouth mixing zones using an autonomous underwater vehicle and a manned boat

    USGS Publications Warehouse

    Jackson, P. Ryan; Reneau, Paul C.

    2014-01-01

    The U.S. Geological Survey (USGS), in cooperation with the National Monitoring Network for U.S. Coastal Waters and Tributaries, launched a pilot project in 2010 to determine the value of integrated synoptic surveys of rivermouths using autonomous underwater vehicle technology in response to a call for rivermouth research, which includes study domains that envelop both the fluvial and lacustrine boundaries of the rivermouth mixing zone. The pilot project was implemented at two Lake Michigan rivermouths with largely different scales, hydrodynamics, and settings, but employing primarily the same survey techniques and methods. The Milwaukee River Estuary Area of Concern (AOC) survey included measurements in the lower 2 to 3 miles of the Milwaukee, Menomonee, and Kinnickinnic Rivers and inner and outer Milwaukee Harbor. This estuary is situated in downtown Milwaukee, Wisconsin, and is the most populated basin that flows directly into Lake Michigan. In contrast, the Manitowoc rivermouth has a relatively small harbor separating the rivermouth from Lake Michigan, and the Manitowoc River Watershed is primarily agricultural. Both the Milwaukee and Manitowoc rivermouths are unregulated and allow free exchange of water with Lake Michigan. This pilot study of the Milwaukee River Estuary and Manitowoc rivermouth using an autonomous underwater vehicle (AUV) paired with a manned survey boat resulted in high spatial and temporal resolution datasets of basic water-quality parameter distributions and hydrodynamics. The AUV performed well in these environments and was found primarily well-suited for harbor and nearshore surveys of three-dimensional water-quality distributions. Both case studies revealed that the use of a manned boat equipped with an acoustic Doppler current profiler (ADCP) and multiparameter sonde (and an optional flow-through water-quality sampling system) was the best option for riverine surveys. To ensure that the most accurate and highest resolution velocity data

  6. Dynamic Response and Maneuvering Strategies of a Hybrid Autonomous Underwater Vehicle in Hovering

    DTIC Science & Technology

    2009-02-01

    Thruster Guards and RTU The drag FDt due to the thruster guards and RTU arms are modeled as follows: Xu|u|t = − 1 2 ρCd(Aguardsx + ARTU ) (3.39) Zw|w|t...1 2 ρCd(Aguardsz + ARTU ) (3.40) where Cd=0.47 is the drag coefficient for a sphere [31], Aguardsx and Aguardsz are the projected area of the...thruster guard in the x- and z-directions, and ARTU is the projected area of the RTU arms. 3.3 Hydrostatics Following the methods in Fossen [24], the

  7. Resolving meso-scale seabed variability using reflection measurements from an autonomous underwater vehicle.

    PubMed

    Holland, Charles W; Nielsen, Peter L; Dettmer, Jan; Dosso, Stan

    2012-02-01

    Seabed geoacoustic variability is driven by geological processes that occur over a wide spectrum of space-time scales. While the acoustics community has some understanding of horizontal fine-scale geoacoustic variability, less than O(10(0)) m, and large-scale variability, greater than O(10(3)) m, there is a paucity of data resolving the geoacoustic meso-scale O(10(0)-10(3)) m. Measurements of the meso-scale along an ostensibly "benign" portion of the outer shelf reveal three classes of variability. The first class was expected and is due to horizontal variability of layer thicknesses: this was the only class that could be directly tied to seismic reflection data. The second class is due to rapid changes in layer properties and/or boundaries, occurring over scales of meters to hundreds of meters. The third class was observed as rapid variations of the angle/frequency dependent reflection coefficient within a single observation and is suggestive of variability at scales of meter or less. Though generally assumed to be negligible in acoustic modeling, the second and third classes are indicative of strong horizontal geoacoustic variability within a given layer. The observations give early insight into possible effects of horizontal geoacoustic variability on long-range acoustic propagation and reverberation. © 2012 Acoustical Society of America

  8. Mechanical model of the ultrafast underwater trap of Utricularia

    NASA Astrophysics Data System (ADS)

    Joyeux, Marc; Vincent, Olivier; Marmottant, Philippe

    2011-02-01

    The underwater traps of the carnivorous plants of the Utricularia species catch their prey through the repetition of an “active slow deflation followed by passive fast suction” sequence. In this paper, we propose a mechanical model that describes both phases and strongly supports the hypothesis that the trap door acts as a flexible valve that buckles under the combined effects of pressure forces and the mechanical stimulation of trigger hairs, and not as a panel articulated on hinges. This model combines two different approaches, namely (i) the description of thin membranes as triangle meshes with strain and curvature energy, and (ii) the molecular dynamics approach, which consists of computing the time evolution of the position of each vertex of the mesh according to Langevin equations. The only free parameter in the expression of the elastic energy is the Young's modulus E of the membranes. The values for this parameter are unequivocally obtained by requiring that the trap model fires, like real traps, when the pressure difference between the outside and the inside of the trap reaches about 15 kPa. Among other results, our simulations show that, for a pressure difference slightly larger than the critical one, the door buckles, slides on the threshold, and finally swings wide open, in excellent agreement with the sequence observed in high-speed videos.

  9. Autonomous Underwater Vehicle Navigation

    DTIC Science & Technology

    2008-02-01

    roll , pitch , and yaw information. We assume the vehicle dynamics are slow, and as such, the coupling between the inclinometers and platform...the vehicle has a nonzero roll or pitch angle, Σu has dimension 3. For this condition, the unobservable subspace is similar to a single beam failure...position is defined in local tangent plane coordinates, where x aligns with north, y aligns with east, and z is down. Euler attitude angles are roll (φ

  10. D Modelling and Mapping for Virtual Exploration of Underwater Archaeology Assets

    NASA Astrophysics Data System (ADS)

    Liarokapis, F.; Kouřil, P.; Agrafiotis, P.; Demesticha, S.; Chmelík, J.; Skarlatos, D.

    2017-02-01

    This paper investigates immersive technologies to increase exploration time in an underwater archaeological site, both for the public, as well as, for researchers and scholars. Focus is on the Mazotos shipwreck site in Cyprus, which is located 44 meters underwater. The aim of this work is two-fold: (a) realistic modelling and mapping of the site and (b) an immersive virtual reality visit. For 3D modelling and mapping optical data were used. The underwater exploration is composed of a variety of sea elements including: plants, fish, stones, and artefacts, which are randomly positioned. Users can experience an immersive virtual underwater visit in Mazotos shipwreck site and get some information about the shipwreck and its contents for raising their archaeological knowledge and cultural awareness.

  11. Underwater 3d Modeling: Image Enhancement and Point Cloud Filtering

    NASA Astrophysics Data System (ADS)

    Sarakinou, I.; Papadimitriou, K.; Georgoula, O.; Patias, P.

    2016-06-01

    This paper examines the results of image enhancement and point cloud filtering on the visual and geometric quality of 3D models for the representation of underwater features. Specifically it evaluates the combination of effects from the manual editing of images' radiometry (captured at shallow depths) and the selection of parameters for point cloud definition and mesh building (processed in 3D modeling software). Such datasets, are usually collected by divers, handled by scientists and used for geovisualization purposes. In the presented study, have been created 3D models from three sets of images (seafloor, part of a wreck and a small boat's wreck) captured at three different depths (3.5m, 10m and 14m respectively). Four models have been created from the first dataset (seafloor) in order to evaluate the results from the application of image enhancement techniques and point cloud filtering. The main process for this preliminary study included a) the definition of parameters for the point cloud filtering and the creation of a reference model, b) the radiometric editing of images, followed by the creation of three improved models and c) the assessment of results by comparing the visual and the geometric quality of improved models versus the reference one. Finally, the selected technique is tested on two other data sets in order to examine its appropriateness for different depths (at 10m and 14m) and different objects (part of a wreck and a small boat's wreck) in the context of an ongoing research in the Laboratory of Photogrammetry and Remote Sensing.

  12. Measurement and modeling of the acoustic field near an underwater vehicle and implications for acoustic source localization.

    PubMed

    Lepper, Paul A; D'Spain, Gerald L

    2007-08-01

    The performance of traditional techniques of passive localization in ocean acoustics such as time-of-arrival (phase differences) and amplitude ratios measured by multiple receivers may be degraded when the receivers are placed on an underwater vehicle due to effects of scattering. However, knowledge of the interference pattern caused by scattering provides a potential enhancement to traditional source localization techniques. Results based on a study using data from a multi-element receiving array mounted on the inner shroud of an autonomous underwater vehicle show that scattering causes the localization ambiguities (side lobes) to decrease in overall level and to move closer to the true source location, thereby improving localization performance, for signals in the frequency band 2-8 kHz. These measurements are compared with numerical modeling results from a two-dimensional time domain finite difference scheme for scattering from two fluid-loaded cylindrical shells. Measured and numerically modeled results are presented for multiple source aspect angles and frequencies. Matched field processing techniques quantify the source localization capabilities for both measurements and numerical modeling output.

  13. 3D photo mosaicing of Tagiri shallow vent field by an autonomous underwater vehicle (3rd report) - Mosaicing method based on navigation data and visual features -

    NASA Astrophysics Data System (ADS)

    Maki, Toshihiro; Ura, Tamaki; Singh, Hanumant; Sakamaki, Takashi

    Large-area seafloor imaging will bring significant benefits to various fields such as academics, resource survey, marine development, security, and search-and-rescue. The authors have proposed a navigation method of an autonomous underwater vehicle for seafloor imaging, and verified its performance through mapping tubeworm colonies with the area of 3,000 square meters using the AUV Tri-Dog 1 at Tagiri vent field, Kagoshima bay in Japan (Maki et al., 2008, 2009). This paper proposes a post-processing method to build a natural photo mosaic from a number of pictures taken by an underwater platform. The method firstly removes lens distortion, invariances of color and lighting from each image, and then ortho-rectification is performed based on camera pose and seafloor estimated by navigation data. The image alignment is based on both navigation data and visual characteristics, implemented as an expansion of the image based method (Pizarro et al., 2003). Using the two types of information realizes an image alignment that is consistent both globally and locally, as well as making the method applicable to data sets with little visual keys. The method was evaluated using a data set obtained by the AUV Tri-Dog 1 at the vent field in Sep. 2009. A seamless, uniformly illuminated photo mosaic covering the area of around 500 square meters was created from 391 pictures, which covers unique features of the field such as bacteria mats and tubeworm colonies.

  14. Autonomous Boolean modeling of gene regulatory networks

    NASA Astrophysics Data System (ADS)

    Socolar, Joshua; Sun, Mengyang; Cheng, Xianrui

    2014-03-01

    In cases where the dynamical properties of gene regulatory networks are important, a faithful model must include three key features: a network topology; a functional response of each element to its inputs; and timing information about the transmission of signals across network links. Autonomous Boolean network (ABN) models are efficient representations of these elements and are amenable to analysis. We present an ABN model of the gene regulatory network governing cell fate specification in the early sea urchin embryo, which must generate three bands of distinct tissue types after several cell divisions, beginning from an initial condition with only two distinct cell types. Analysis of the spatial patterning problem and the dynamics of a network constructed from available experimental results reveals that a simple mechanism is at work in this case. Supported by NSF Grant DMS-10-68602

  15. A Proposal for Modeling Real Hardware, Weather and Marine Conditions for Underwater Sensor Networks

    PubMed Central

    Climent, Salvador; Capella, Juan Vicente; Blanc, Sara; Perles, Angel; Serrano, Juan José

    2013-01-01

    Network simulators are useful for researching protocol performance, appraising new hardware capabilities and evaluating real application scenarios. However, these tasks can only be achieved when using accurate models and real parameters that enable the extraction of trustworthy results and conclusions. This paper presents an underwater wireless sensor network ecosystem for the ns-3 simulator. This ecosystem is composed of a new energy-harvesting model and a low-cost, low-power underwater wake-up modem model that, alongside existing models, enables the performance of accurate simulations by providing real weather and marine conditions from the location where the real application is to be deployed. PMID:23748171

  16. Modeled and Measured Underwater Sound Isopleths and Implications for Marine Mammal Mitigation in Alaska.

    PubMed

    Aerts, Lisanne A M; Streever, Bill

    2016-01-01

    Before operating air guns in Alaska, industry is usually required to model underwater sound isopleths, some of which have implications for the mitigation and monitoring of potential marine mammal impacts. Field measurements are often required to confirm or revise model predictions. We compared modeled and measured air gun sound isopleths from 2006 to 2012 and found poor agreement. Natural variability in the marine environment, application of precautionary correction factors, and data interpretation in the generation of circular isopleths all contributed to the observed poor agreement. A broader understanding of the realities of modeled and measured underwater sound isopleths will contribute to improved mitigation practices.

  17. The Modeling and Simulation of Underwater Acoustic Energy Exposure Due to Near Surface Explosions on Marine Mammals

    DTIC Science & Technology

    2016-06-13

    NUWC-NPT Reprint Report 11,773 18 October 2005 The Modeling and Simulation of Underwater Acoustic Energy Exposure Due to Near Surface Explosions...Underwater Acoustic Energy Exposure Due to Near Surface Explosions on Marine Mammals 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6... energy are released into the surrounding underwater environment. A simulation tool is developed to predict the biological exposure effects from multiple

  18. Numerical modelling of underwater detonation of non-ideal condensed-phase explosives

    NASA Astrophysics Data System (ADS)

    Schoch, Stefan; Nikiforakis, Nikolaos

    2015-01-01

    The interest in underwater detonation tests originated from the military, since the expansion and subsequent collapse of the explosive bubble can cause considerable damage to surrounding structures or vessels. In military applications, the explosive is typically represented as a pre-burned material under high pressure, a reasonable assumption due to the short reaction zone lengths, and complete detonation of the unreacted explosive. Hence, numerical simulations of underwater detonation tests have been primarily concerned with the prediction of target loading and the damage incurred rather than the accurate modelling of the underwater detonation process. The mining industry in contrast has adopted the underwater detonation test as a means to experimentally characterise the energy output of their highly non-ideal explosives depending on explosive type and charge configuration. This characterisation requires a good understanding of how the charge shape, pond topography, charge depth, and additional charge confinement affect the energy release, some of which can be successfully quantified with the support of accurate numerical simulations. In this work, we propose a numerical framework which is able to capture the non-ideal explosive behaviour and in addition is capable of capturing both length scales: the reaction zone and the pond domain. The length scale problem is overcome with adaptive mesh refinement, which, along with the explosive model, is validated against experimental data of various TNT underwater detonations. The variety of detonation and bubble behaviour observed in non-ideal detonations is demonstrated in a parameter study over the reactivity of TNT. A representative underwater mining test containing an ammonium-nitrate fuel-oil ratestick charge is carried out to demonstrate that the presented method can be readily applied alongside experimental underwater detonation tests.

  19. Modeling and simulation of crack detection for underwater structures using an ACFM method

    NASA Astrophysics Data System (ADS)

    Li, Wei; Chen, Guoming; Yin, Xiaokang; Zhang, Chuanrong; Liu, Tao

    2013-01-01

    Considering the influence of seawater environment, numerical model of the alternating current field measurement (ACFM) method was built for underwater structure surface defect detection in this article. Based on ACFM principle and ANSYS simulation software, finite element simulation was performed to investigate rules and characteristics of the electromagnetic signal distributions in regions with defect, which are verified by the underwater artificial crack detection experiment. The experiment results show that the distributions of electromagnetic signals picked up in the artificial crack experiment are accord with the simulation results and the numerical model is validated.

  20. Skin-friction drag analysis from the forced convection modeling in simplified underwater swimming.

    PubMed

    Polidori, G; Taïar, R; Fohanno, S; Mai, T H; Lodini, A

    2006-01-01

    This study deals with skin-friction drag analysis in underwater swimming. Although lower than profile drag, skin-friction drag remains significant and is the second and only other contribution to total drag in the case of underwater swimming. The question arises whether varying the thermal gradient between the underwater swimmer and the pool water may modify the surface shear stress distribution and the resulting skin-friction drag acting on a swimmer's body. As far as the authors are aware, such a question has not previously been addressed. Therefore, the purpose of this study was to quantify the effect of this thermal gradient by using the integral formalism applied to the forced convection theory. From a simplified model in a range of pool temperatures (20-30 degrees C) it was demonstrated that, whatever the swimming speeds, a 5.3% reduction in the skin-friction drag would occur with increasing average boundary-layer temperature provided that the flow remained laminar. However, as the majority of the flow is actually turbulent, a turbulent flow analysis leads to the major conclusion that friction drag is a function of underwater speed, leading to a possible 1.5% reduction for fast swimming speeds above 1m/s. Furthermore, simple correlations between the surface shear stress and resulting skin-friction drag are derived in terms of the boundary-layer temperature, which may be readily used in underwater swimming situations.

  1. A Comprehensive Study on the Internet of Underwater Things: Applications, Challenges, and Channel Models

    PubMed Central

    Wu, Geng-De; Huang, Chun-Ju

    2017-01-01

    The Internet of Underwater Things (IoUT) is a novel class of Internet of Things (IoT), and is defined as the network of smart interconnected underwater objects. IoUT is expected to enable various practical applications, such as environmental monitoring, underwater exploration, and disaster prevention. With these applications, IoUT is regarded as one of the potential technologies toward developing smart cities. To support the concept of IoUT, Underwater Wireless Sensor Networks (UWSNs) have emerged as a promising network system. UWSNs are different from the traditional Territorial Wireless Sensor Networks (TWSNs), and have several unique properties, such as long propagation delay, narrow bandwidth, and low reliability. These unique properties would be great challenges for IoUT. In this paper, we provide a comprehensive study of IoUT, and the main contributions of this paper are threefold: (1) we introduce and classify the practical underwater applications that can highlight the importance of IoUT; (2) we point out the differences between UWSNs and traditional TWSNs, and these differences are the main challenges for IoUT; and (3) we investigate and evaluate the channel models, which are the technical core for designing reliable communication protocols on IoUT. PMID:28640220

  2. A Comprehensive Study on the Internet of Underwater Things: Applications, Challenges, and Channel Models.

    PubMed

    Kao, Chien-Chi; Lin, Yi-Shan; Wu, Geng-De; Huang, Chun-Ju

    2017-06-22

    The Internet of Underwater Things (IoUT) is a novel class of Internet of Things (IoT), and is defined as the network of smart interconnected underwater objects. IoUT is expected to enable various practical applications, such as environmental monitoring, underwater exploration, and disaster prevention. With these applications, IoUT is regarded as one of the potential technologies toward developing smart cities. To support the concept of IoUT, Underwater Wireless Sensor Networks (UWSNs) have emerged as a promising network system. UWSNs are different from the traditional Territorial Wireless Sensor Networks (TWSNs), and have several unique properties, such as long propagation delay, narrow bandwidth, and low reliability. These unique properties would be great challenges for IoUT. In this paper, we provide a comprehensive study of IoUT, and the main contributions of this paper are threefold: (1) we introduce and classify the practical underwater applications that can highlight the importance of IoUT; (2) we point out the differences between UWSNs and traditional TWSNs, and these differences are the main challenges for IoUT; and (3) we investigate and evaluate the channel models, which are the technical core for designing reliable communication protocols on IoUT.

  3. Accuracy Assessment of Underwater Photogrammetric Three Dimensional Modelling for Coral Reefs

    NASA Astrophysics Data System (ADS)

    Guo, T.; Capra, A.; Troyer, M.; Gruen, A.; Brooks, A. J.; Hench, J. L.; Schmitt, R. J.; Holbrook, S. J.; Dubbini, M.

    2016-06-01

    Recent advances in automation of photogrammetric 3D modelling software packages have stimulated interest in reconstructing highly accurate 3D object geometry in unconventional environments such as underwater utilizing simple and low-cost camera systems. The accuracy of underwater 3D modelling is affected by more parameters than in single media cases. This study is part of a larger project on 3D measurements of temporal change of coral cover in tropical waters. It compares the accuracies of 3D point clouds generated by using images acquired from a system camera mounted in an underwater housing and the popular GoPro cameras respectively. A precisely measured calibration frame was placed in the target scene in order to provide accurate control information and also quantify the errors of the modelling procedure. In addition, several objects (cinder blocks) with various shapes were arranged in the air and underwater and 3D point clouds were generated by automated image matching. These were further used to examine the relative accuracy of the point cloud generation by comparing the point clouds of the individual objects with the objects measured by the system camera in air (the best possible values). Given a working distance of about 1.5 m, the GoPro camera can achieve a relative accuracy of 1.3 mm in air and 2.0 mm in water. The system camera achieved an accuracy of 1.8 mm in water, which meets our requirements for coral measurement in this system.

  4. Magnetic structure of Bayonnaise knoll caldera including Hakurei hydrothermal site obtained from near-bottom magnetic vector field mapping by autonomous underwater vehicle

    NASA Astrophysics Data System (ADS)

    Honsho, C.; Ura, T.; Kim, K.

    2012-12-01

    The Bayonnaise knoll caldera is one of the silicic submarine calderas in the Izu-Ogasawara Arc in Japan. In 2003, a large-scale hydrothermal deposit was found in the caldera, called the Hakurei deposit. The caldera had been explored by four surveys using autonomous underwater vehicles (AUVs) from 2008 to 2011, and the near-bottom magnetic field was mapped over about 75% of the caldera floor. We carried out detailed correction for the magnetic field produced by the vehicle body, which allowed us to take advantage of the vector anomaly instead of the total anomaly for the magnetic inversion. We applied the inversion method using the block model together with the Akaike's Bayesian information criterion (ABIC). One remarkable thing is that we recognized significant difference between the magnetic inversion result using the vector anomaly and that using the total anomaly: the latter result explains the observed total anomalies excellently, but does not explain the vector anomalies adequately. Except for a rare case where the vector anomaly is perpendicular to the main field throughout, the total anomaly should be sufficient for evaluating the entire field, provided that the data is collected in sufficiently high density. In fact, the track lines of our survey sometimes separate from each other by about twice the altitude of the vehicle (100 m), which can lead to considerable aliasing in the sampled field. The vector anomaly can provide vital information in such a situation. The obtained magnetization distribution is well correlated with the topography. The caldera rim and central cone have weak magnetization, which is consistent with the fact that they consist of dacite rocks. On the other hand, the caldera floor shows high magnetization, which implies the existence of basaltic rocks. The high magnetization appears to continue north and south beyond the caldera rim, forming an NS-trending high magnetization zone. Because the caldera floor is generally covered with

  5. Active State Model for Autonomous Systems

    NASA Technical Reports Server (NTRS)

    Park, Han; Chien, Steve; Zak, Michail; James, Mark; Mackey, Ryan; Fisher, Forest

    2003-01-01

    The concept of the active state model (ASM) is an architecture for the development of advanced integrated fault-detection-and-isolation (FDI) systems for robotic land vehicles, pilotless aircraft, exploratory spacecraft, or other complex engineering systems that will be capable of autonomous operation. An FDI system based on the ASM concept would not only provide traditional diagnostic capabilities, but also integrate the FDI system under a unified framework and provide mechanism for sharing of information between FDI subsystems to fully assess the overall health of the system. The ASM concept begins with definitions borrowed from psychology, wherein a system is regarded as active when it possesses self-image, self-awareness, and an ability to make decisions itself, such that it is able to perform purposeful motions and other transitions with some degree of autonomy from the environment. For an engineering system, self-image would manifest itself as the ability to determine nominal values of sensor data by use of a mathematical model of itself, and selfawareness would manifest itself as the ability to relate sensor data to their nominal values. The ASM for such a system may start with the closed-loop control dynamics that describe the evolution of state variables. As soon as this model was supplemented with nominal values of sensor data, it would possess self-image. The ability to process the current sensor data and compare them with the nominal values would represent self-awareness. On the basis of self-image and self-awareness, the ASM provides the capability for self-identification, detection of abnormalities, and self-diagnosis.

  6. An autonomous DNA model for finite state automata.

    PubMed

    Martinez-Perez, Israel M; Zimmermann, Karl-Heinz; Ignatova, Zoya

    2009-01-01

    In this paper we introduce an autonomous DNA model for finite state automata. This model called sticker automaton model is based on the hybridisation of single stranded DNA molecules (stickers) encoding transition rules and input data. The computation is carried out in an autonomous manner by one enzyme which allows us to determine whether a resulting double-stranded DNA molecule belongs to the automaton's language or not.

  7. Modeling underwater transport of oil spilled from deepwater area in the South China Sea

    NASA Astrophysics Data System (ADS)

    Chen, Haibo; An, Wei; You, Yunxiang; Lei, Fanghui; Zhao, Yupeng; Li, Jianwei

    2016-01-01

    Based on a Lagrangian integral technique and Lagrangian particle-tracking technique, a numerical model was developed to simulate the underwater transport of oil from a deepwater spill. This model comprises two submodels: a plume dynamics model and an advection-diffusion model. The former is used to simulate the stages dominated by the initial jet momentum and plume buoyancy of the spilled oil, while the latter is used to simulate the stage dominated by the ambient current and turbulence. The model validity was verified through comparisons of the model predictions with experimental data from several laboratory flume experiments and a field experiment. To demonstrate the capability of the model further, it was applied to the simulation of a hypothetical oil spill occurring at the seabed of a deepwater oil/gas field in the South China Sea. The results of the simulation would be useful for contingency planning with regard to the emergency response to an underwater oil spill.

  8. A nonlinear modeling framework for the detection of underwater objects in hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Gillis, David B.

    2016-05-01

    The detection of underwater objects of interest (or targets) in hyperspectral imagery is a challenging problem, with a number of complications that are not present in land-based hyperspectral target detection. The main challenge in underwater detection is that, in contrast to land, where the observed spectrum of an associated target is largely independent of the surrounding background (e.g. the signature of a tank looks more or less the same whether it is on a road or in a field of grass), the observed spectrum of an underwater target is a highly nonlinear function of the background - that is, the optical properties of the water body that the object is submerged in, as well as the depth of the target. As a result, the same object in different types of water and/or at different depths will in general have very different observed spectral signatures. In this work, we present a general overview of the various challenges involved in underwater detection, and present a novel approach that fuses forward radiative-transfer modeling, ocean color predictions, and nonlinear mathematical techniques (manifold learning) to model both the background and target signature(s) and perform detection over a wide range of environmental conditions and depths.

  9. Experimental validation of a Monte Carlo model for determining the temporal response of the underwater optical communications channel

    NASA Astrophysics Data System (ADS)

    Cochenour, Brandon M.; Laux, Alan E.

    2015-05-01

    Recent interest in high speed laser communications underwater has restimulated theoretical studies in laser propagation in turbid media. In particular, the characterization of temporal dispersion is of paramount importance in order to predict the bandwidth and capacity of underwater optical channels. While the temporal aspects of underwater laser propagation have received attention from the modeling community in the past, few if any of these models have been validated with experimental data. However recent advances in hardware technology now enable experimental characterization at high speeds (~GHz). Such measurements have been made by the authors.1 In this work, we develop a Monte Carlo model, and present initial results validated against the aforementioned experimental data.

  10. Modelling progressive autonomic failure in MSA: where are we now?

    PubMed

    Stemberger, Sylvia; Wenning, Gregor K

    2011-05-01

    Multiple system atrophy (MSA) is a fatal late-onset α-synucleinopathy that presents with features of ataxia, Parkinsonism, and pyramidal dysfunction in any combination. Over the last decade, efforts have been made to develop preclinical MSA testbeds for novel interventional strategies. The main focus has been on murine analogues of MSA-linked motor features and their underlying brainstem, cerebellar and basal ganglia pathology. Although progressive autonomic failure (AF) is a prominent clinical feature of patients with MSA, reflecting a disruption of both central and peripheral autonomic networks controlling cardiovascular, respiratory, urogenital, gastrointestinal and sudomotor functions, attempts of modelling this aspect of the human disease have been limited. However, emerging evidence suggests that AF-like features may occur in transgenic MSA models reflecting α-synucleinopathy lesions in distributed autonomic networks. Further research is needed to fully characterize both autonomic and motor features in optimized preclinical MSA models.

  11. Instruments and MethodsAutonomous underwater vehicles (AUVs) and investigations of the ice-ocean interface in Antarctic and Arctic waters

    NASA Astrophysics Data System (ADS)

    Dowdeswell, J. A.; Evans, J.; Mugford, R.; Griffiths, G.; McPhail, S.; Millard, N.; Stevenson, P.; Brandon, M. A.; Banks, C.; Heywood, K. J.; Price, M. R.; Dodd, P. A.; Jenkins, A.; Nicholls, K. W.; Hayes, D.; Abrahamsen, E. P.; Tyler, P.; Bett, B.; Jones, D.; Wadhams, P.; Wilkinson, J. P.; Stansfield, K.; Ackley, S.

    Limitations of access have long restricted exploration and investigation of the cavities beneath ice shelves to a small number of drillholes. Studies of sea-ice underwater morphology are limited largely to scientific utilization of submarines. Remotely operated vehicles, tethered to a mother ship by umbilical cable, have been deployed to investigate tidewater-glacier and ice-shelf margins, but their range is often restricted. The development of free-flying autonomous underwater vehicles (AUVs) with ranges of tens to hundreds of kilometres enables extensive missions to take place beneath sea ice and floating ice shelves. Autosub2 is a 3600 kg, 6.7 m long AUV, with a 1600 m operating depth and range of 400 km, based on the earlier Autosub1 which had a 500m depth limit. A single direct-drive d.c. motor and five-bladed propeller produce speeds of 1-2 ms-1. Rear-mounted rudder and stern-plane control yaw, pitch and depth. The vehicle has three sections. The front and rear sections are free-flooding, built around aluminium extrusion space-frames covered with glass-fibre reinforced plastic panels. The central section has a set of carbon-fibre reinforced plastic pressure vessels. Four tubes contain batteries powering the vehicle. The other three house vehicle-control systems and sensors. The rear section houses subsystems for navigation, control actuation and propulsion and scientific sensors (e.g. digital camera, upward-looking 300 kHz acoustic Doppler current profiler, 200 kHz multibeam receiver). The front section contains forward-looking collision sensor, emergency abort, the homing systems, Argos satellite data and location transmitters and flashing lights for relocation as well as science sensors (e.g. twin conductivity-temperature-depth instruments, multibeam transmitter, sub-bottom profiler, AquaLab water sampler). Payload restrictions mean that a subset of scientific instruments is actually in place on any given dive. The scientific instruments carried on Autosub

  12. A new 3-D-modelling method to extract subtransect dimensions from underwater videos

    NASA Astrophysics Data System (ADS)

    Fillinger, L.; Funke, T.

    2012-12-01

    Underwater video transects have become a common tool for quantitative analysis of the seafloor. However a major difficulty remains in the accurate determination of the area surveyed as underwater navigation can be unreliable and image scaling does not always compensate for distortions due to perspective and topography. Depending on the camera setup and available instruments, different methods of surface measurement are applied which make it difficult to compare data obtained by different vehicles. 3-D modelling of the seafloor based on 2-D video data and a reference scale can be used to compute subtransects dimensions. Focussing on the length of the subtransect, the data obtained from 3-D models created with the software PhotoModeler Scanner are compared with those determined from underwater acoustic positioning (Ultra-Short BaseLine - USBL) and bottom tracking (Doppler Velocity Log - DVL). 3-D models building and scaling was successfully conducted on all three tested setups while the distortion of the reference scales due to substrate roughness was identified as the main source of imprecision. Acoustic positioning was generally inaccurate and DVL unreliable on rough terrain. Subtransect lengths assessed with PhotoModeler were on average 20% longer than those derived from the USBL due to the higher spatial resolution and the inclusion of slope. On a high relief wall, DVL and 3-D modelling yielded similar results. At present, 3-D modelling is the most powerful, albeit the most time-consuming, method for the accurate determination of video subtransect dimensions.

  13. A new 3-D modelling method to extract subtransect dimensions from underwater videos

    NASA Astrophysics Data System (ADS)

    Fillinger, L.; Funke, T.

    2013-04-01

    Underwater video transects have become a common tool for quantitative analysis of the seafloor. However a major difficulty remains in the accurate determination of the area surveyed as underwater navigation can be unreliable and image scaling does not always compensate for distortions due to perspective and topography. Depending on the camera set-up and available instruments, different methods of surface measurement are applied, which make it difficult to compare data obtained by different vehicles. 3-D modelling of the seafloor based on 2-D video data and a reference scale can be used to compute subtransect dimensions. Focussing on the length of the subtransect, the data obtained from 3-D models created with the software PhotoModeler Scanner are compared with those determined from underwater acoustic positioning (ultra short baseline, USBL) and bottom tracking (Doppler velocity log, DVL). 3-D model building and scaling was successfully conducted on all three tested set-ups and the distortion of the reference scales due to substrate roughness was identified as the main source of imprecision. Acoustic positioning was generally inaccurate and bottom tracking unreliable on rough terrain. Subtransect lengths assessed with PhotoModeler were on average 20% longer than those derived from acoustic positioning due to the higher spatial resolution and the inclusion of slope. On a high relief wall bottom tracking and 3-D modelling yielded similar results. At present, 3-D modelling is the most powerful, albeit the most time-consuming, method for accurate determination of video subtransect dimensions.

  14. Research on biomimetic underwater vehicles for underwater ISR

    NASA Astrophysics Data System (ADS)

    Szymak, Piotr; Praczyk, Tomasz; Naus, Krzysztof; Szturomski, Bogdan; Malec, Marcin; Morawski, Marcin

    2016-05-01

    Autonomous Biomimetic Underwater Vehicles BUVs driven by an undulating propulsion are a new branch in an area of an underwater robotics. They imitate both the construction and kinematics of a motion of underwater living organisms, e.g. fishes. Such vehicles have several features crucial from the point of view of military applications, e.g. larger secrecy and potential range of operation. The paper presents results of the research on BUVs carried out within two (Polish and EDA) projects both led by Polish Naval Academy. At the beginning, the initial efforts in building Polish BUV called CyberFish are included. Then, selected results of the tests of subsystems, e.g. navigational and 3D model of BUV built within national project are described. Next, the initial research achieved in the international project are showed. At the end, the schedule of the research planned to carry out within both projects is inserted. The paper is mainly focused on the hardware development of the BUVs.

  15. Modeling and control of an unmanned underwater vehicle using a mass moving system

    NASA Astrophysics Data System (ADS)

    Byun, Seung-Woo; Kim, Donghee; Choi, Hyeung-Sik; Kim, Joon-Young

    2015-03-01

    This paper describes the mathematical modeling and control algorithms of an unmanned underwater vehicle (UUV) named Minekiller. This UUV has two longitudinal thrusters, one vertical thruster, and an internal mass moving system, which can control the pitch rate. The UUV is equipped with a movable mass for pitch control. It is different from other common UUVs, in that it can maintain a static pitch angle. The UUV's 6-DOF (Degrees of Freedom) dynamics model is derived from the hydrodynamic forces and moments acting on it. We applied these hydrodynamic coefficients to dynamic modeling for numerical simulations by MATLAB/SIMULINK©. To compare the performance in various cases, we used a PID controller for depth and heading control. Also, the navigation controller can analyze the way-point tracking performance. These simulation results show the performance of the control algorithms and maneuvering performance of the underwater vehicle.

  16. Modeling the underwater light field fluctuations in coastal oceanic waters: Validation with experimental data

    NASA Astrophysics Data System (ADS)

    Sundarabalan, Balasubramanian; Shanmugam, Palanisamy; Ahn, Yu-Hwan

    2016-03-01

    Modeling of the wave-induced underwater light fluctuations at near-surface depths in coastal oceanic waters is challenging because of the surface roughness and strong anisotropic effects of the light field. In the present work, a simple and computationally efficient radiative transfer model is used for the wind-driven sea surface for simulating underwater light fields such as downwelling irradiance ( E d ), upwelling irradiance ( E u ), and upwelling radiance ( L u ) in a spatial domain. It is an extension of our previous work that essentially combines the air-sea interface of the wind-driven sea surface with transmittance and reflectance along with the diffuse and direct components of the homogenous and inhomogeneous water column. The present model simulates underwater light fields for any possible values of absorption and backscattering coefficients. To assess the performance of the model, the E d , E u , and L u profiles predicted by the model are compared with experimental data from relatively clear and turbid coastal waters. Statistical results show significantly low mean relative differences regardless of the wavelength. Comparison of the simulated and in-situ time series data measured over rough sea surfaces demonstrates that model-observation agreement is good for the present model. The Hydrolight model when implemented with the modified bottom reflectance and phase function provides significantly better results than the original Hydrolight model without consideration of the bottom slope and vertically varying phase function. However, these results are non-spatial and have errors fluctuating at different wavelengths. To further demonstrate the efficiency of the present model, spatial distribution patterns of the underwater light fields are simulated based on the measured data from a coastal station for different solar zenith angles (under sunny condition). Simulated wave-induced fluctuations of the underwater lights fields show a good consistency with in

  17. Spatially complex distribution of dissolved manganese in a fjord as revealed by high-resolution in situ sensing using the autonomous underwater vehicle Autosub.

    PubMed

    Statham, P J; Connelly, D P; German, C R; Brand, T; Overnell, J O; Bulukin, E; Millard, N; McPhail, S; Pebody, M; Perrett, J; Squire, M; Stevenson, P; Webb, A

    2005-12-15

    Loch Etive is a fjordic system on the west coast of Scotland. The deep waters of the upper basin are periodically isolated, and during these periods oxygen is lost through benthic respiration and concentrations of dissolved manganese increase. In April 2000 the autonomous underwater vehicle (AUV) Autosub was fitted with an in situ dissolved manganese analyzer and was used to study the spatial variability of this element together with oxygen, salinity, and temperature throughout the basin. Six along-loch transects were completed at either constant height above the seafloor or at constant depth below the surface. The ca. 4000 in situ 10-s-average dissolved Mn (Mnd) data points obtained provide a new quasi-synoptic and highly detailed view of the distribution of manganese in this fjordic environment not possible using conventional (water bottle) sampling. There is substantial variability in concentrations (<25 to >600 nM) and distributions of Mnd. Surface waters are characteristically low in Mnd reflecting mixing of riverine and marine end-member waters, both of which are low in Mnd. The deeper waters are enriched in Mnd, and as the water column always contains some oxygen, this must reflect primarily benthic inputs of reduced dissolved Mn. However, this enrichment of Mnd is spatially very variable, presumably as a result of variability in release of Mn coupled with mixing of water in the loch and removal processes. This work demonstrates how AUVs coupled with chemical sensors can reveal substantial small-scale variability of distributions of chemical species in coastal environments that would not be resolved by conventional sampling approaches. Such information is essential if we are to improve our understanding of the nature and significance of the underlying processes leading to this variability.

  18. Numerical Modeling of Underwater Explosion by One-Dimensional ANSYS-AUTODYN

    NASA Astrophysics Data System (ADS)

    Huang, Hao; Jie Jiao, Qing; Nie, Jian Xin; Qin, Jian Feng

    2011-10-01

    This article presents numerical simulation of underwater explosions using a one-dimensional "wedge" model of ANSYS-AUTODYN explicit software for nonlinear dynamics, provided by ANSYS Century Dynamics, Inc. (Canonsburg, PA, USA). Through numerical analysis of a typical underwater TNT explosion problems, the effects of the quadratic and linear viscosity on the key phenomenon of this complicated energetic physical process are conducted. The results show that appropriate values exist for these two viscosities to model the process in given mesh sizes. Based on these preliminary simulations, values of quadratic and linear viscosity, 1 and 0.034, 1 and 0.068 are determined for the ranges of scaled distance from 3 to 10 and 1.5 to 3, respectively. Effects of charge depth, charge mass, and mesh density on the shock wave and bubble pulse parameters are performed for four different explosives, 2,4,5-trinitrotoluene (TNT), H-6, pentolite, and pentaerythritol tetranitrate (PETN). All of the results are compared with empirical equations and show that the ANSYS-AUTODYN software can be used to model and capture the major features of underwater explosion phenomena at acceptable accuracy and timesaving.

  19. Reduced-order model for underwater target identification using proper orthogonal decomposition

    NASA Astrophysics Data System (ADS)

    Ramesh, Sai Sudha; Lim, Kian Meng

    2017-03-01

    Research on underwater acoustics has seen major development over the past decade due to its widespread applications in domains such as underwater communication/navigation (SONAR), seismic exploration and oceanography. In particular, acoustic signatures from partially or fully buried targets can be used in the identification of buried mines for mine counter measures (MCM). Although there exist several techniques to identify target properties based on SONAR images and acoustic signatures, these methods first employ a feature extraction method to represent the dominant characteristics of a data set, followed by the use of an appropriate classifier based on neural networks or the relevance vector machine. The aim of the present study is to demonstrate the applications of proper orthogonal decomposition (POD) technique in capturing dominant features of a set of scattered pressure signals, and subsequent use of the POD modes and coefficients in the identification of partially buried underwater target parameters such as its location, size and material density. Several numerical examples are presented to demonstrate the performance of the system identification method based on POD. Although the present study is based on 2D acoustic model, the method can be easily extended to 3D models and thereby enables cost-effective representations of large-scale data.

  20. A Model-Driven Architecture Approach for Modeling, Specifying and Deploying Policies in Autonomous and Autonomic Systems

    NASA Technical Reports Server (NTRS)

    Pena, Joaquin; Hinchey, Michael G.; Sterritt, Roy; Ruiz-Cortes, Antonio; Resinas, Manuel

    2006-01-01

    Autonomic Computing (AC), self-management based on high level guidance from humans, is increasingly gaining momentum as the way forward in designing reliable systems that hide complexity and conquer IT management costs. Effectively, AC may be viewed as Policy-Based Self-Management. The Model Driven Architecture (MDA) approach focuses on building models that can be transformed into code in an automatic manner. In this paper, we look at ways to implement Policy-Based Self-Management by means of models that can be converted to code using transformations that follow the MDA philosophy. We propose a set of UML-based models to specify autonomic and autonomous features along with the necessary procedures, based on modification and composition of models, to deploy a policy as an executing system.

  1. Measuring and modeling the bubble population produced by an underwater explosion.

    PubMed

    Holt, Fred D; Lee Culver, R

    2011-11-01

    Underwater explosions have been studied intensively in the United States since 1941 [e.g., R. H. Cole, Underwater Explosions (Princeton University Press, Princeton, NJ, 1945), pp. 3-13]. Research to date has primarily focused on the initial shock and subsequent pressure waves caused by the oscillations of the "gas-globe" resulting from charge detonation. These phenomena have relatively short timescales (typically less than 2 s). However, after the gas-globe rises through the water column and breaks the surface, there remains behind a cloud of bubbles and perhaps debris from the explosion container which has been markedly less studied. A recent experiment measured the spatial and temporal acoustic response of the bubble cloud resulting from a 13.6 kg PBXN-111 charge detonated at 15.2 m (50 ft) depth. A directional projector was used to propagate linear frequency-modulated (5-65 kHz) and 40 kHz tonal pulses through the bubble cloud. Two hydrophone arrays were positioned so as to measure the energy lost in propagating through the bubble cloud. Three methods have been utilized to invert measurements and estimate the bubble population. The bubble population estimates have been used to develop a model for the bubble population resulting from an underwater explosion.

  2. An Analytical Thermal Model for Autonomous Soaring Research

    NASA Technical Reports Server (NTRS)

    Allen, Michael

    2006-01-01

    A viewgraph presentation describing an analytical thermal model used to enable research on autonomous soaring for a small UAV aircraft is given. The topics include: 1) Purpose; 2) Approach; 3) SURFRAD Data; 4) Convective Layer Thickness; 5) Surface Heat Budget; 6) Surface Virtual Potential Temperature Flux; 7) Convective Scaling Velocity; 8) Other Calculations; 9) Yearly trends; 10) Scale Factors; 11) Scale Factor Test Matrix; 12) Statistical Model; 13) Updraft Strength Calculation; 14) Updraft Diameter; 15) Updraft Shape; 16) Smoothed Updraft Shape; 17) Updraft Spacing; 18) Environment Sink; 19) Updraft Lifespan; 20) Autonomous Soaring Research; 21) Planned Flight Test; and 22) Mixing Ratio.

  3. Automated gravity gradient tensor inversion for underwater object detection

    NASA Astrophysics Data System (ADS)

    Wu, Lin; Tian, Jinwen

    2010-12-01

    Underwater abnormal object detection is a current need for the navigation security of autonomous underwater vehicles (AUVs). In this paper, an automated gravity gradient tensor inversion algorithm is proposed for the purpose of passive underwater object detection. Full-tensor gravity gradient anomalies induced by an object in the partial area can be measured with the technique of gravity gradiometry on an AUV. Then the automated algorithm utilizes the anomalies, using the inverse method to estimate the mass and barycentre location of the arbitrary-shaped object. A few tests on simple synthetic models will be illustrated, in order to evaluate the feasibility and accuracy of the new algorithm. Moreover, the method is applied to a complicated model of an abnormal object with gradiometer and AUV noise, and interference from a neighbouring illusive smaller object. In all cases tested, the estimated mass and barycentre location parameters are found to be in good agreement with the actual values.

  4. A Stratified Acoustic Model Accounting for Phase Shifts for Underwater Acoustic Networks

    PubMed Central

    Wang, Ping; Zhang, Lin; Li, Victor O. K.

    2013-01-01

    Accurate acoustic channel models are critical for the study of underwater acoustic networks. Existing models include physics-based models and empirical approximation models. The former enjoy good accuracy, but incur heavy computational load, rendering them impractical in large networks. On the other hand, the latter are computationally inexpensive but inaccurate since they do not account for the complex effects of boundary reflection losses, the multi-path phenomenon and ray bending in the stratified ocean medium. In this paper, we propose a Stratified Acoustic Model (SAM) based on frequency-independent geometrical ray tracing, accounting for each ray's phase shift during the propagation. It is a feasible channel model for large scale underwater acoustic network simulation, allowing us to predict the transmission loss with much lower computational complexity than the traditional physics-based models. The accuracy of the model is validated via comparisons with the experimental measurements in two different oceans. Satisfactory agreements with the measurements and with other computationally intensive classical physics-based models are demonstrated. PMID:23669708

  5. High-Resolution Magnetic Field and Bathymetric Imaging of Hydrothermal Vent Areas using Autonomous Underwater Vehicles, Remotely Operated Vehicles and Submersibles

    NASA Astrophysics Data System (ADS)

    Tivey, M.

    2003-04-01

    High-resolution, near-bottom bathymetric and magnetic field surveys have been carried out over hydrothermal vent areas using the autonomous underwater vehicle ABE, the ROV Jason and ALVIN. Bathymetry is measured using a 675 kHz, scanning pencil-beam altimeter and, most recently, a 200 kHz swath mapping sonar. Vehicle depth is obtained by pressure sensor and vector magnetic field is measured using either a 3-axis fluxgate or, most recently, a digital magneto-resistor sensor. Typical survey altitude ranges from 20 m (Jason, ALVIN) to 40-60 m (ABE), with line spacing ranging from 20 to 40-60 m respectively. This survey geometry provides sufficient resolution for the detection of magnetic anomalies associated with geological features, most notably hydrothermal vents. We present detailed surveys over 5 hydrothermal sites found at mid-ocean ridges that range from fast to slow spreading. The TAG hydrothermal area, on the slow spreading Mid-Atlantic Ridge, was imaged using ALVIN in 1993 and has a magnetic low directly beneath the active chimney complex. On the intermediate-rate Endeavour segment of the Juan de Fuca Ridge (JDF), we imaged individual chimneys of Main Endeavour Field (MEF) and found that they are associated with discrete magnetic lows. On Explorer Ridge, ABE mapping in 2002 revealed that the Magic Mountain hydrothermal area is also associated with a region of low magnetization. In 2002, at the intermediate-rate Galapagos Rift at 86W, ABE mapped the original "Rose Garden" hydrothermal area, which has now become inactive. This site has a magnetic low associated with it while only 200 m NW of this site, an area of recent low-T hydrothermal activity (i.e. Rosebud site) does not produce a magnetic response. A 2001 ABE bathymetric and magnetic survey at the EPR crest at 9 50N shows weak magnetic anomaly lows associated with active high-T venting in the axial trough. The observed magnetic anomalies share a number of common features, most notably a circular plan view

  6. Bluefin 9M AUV Survey of the Hubbard Glacier Morainal Bank: Proof-of-Concept Study of Autonomous Underwater Vehicle Investigations Proximal to a Tidewater Glacier

    NASA Astrophysics Data System (ADS)

    Goff, J. A.; Gulick, S. P. S.; Lawson, D. E.; O'Halloran, W.

    2014-12-01

    Hubbard Glacier is one of the few advancing tidewater glaciers in the world, offering a premier opportunity for studying ice/sediment/seawater interactions at a tidewater glacier front that is in contact with the stabilizing submarine morainal bank. However, the seafloor and water column proximal to the ice face of a marine-terminating glacier is one of the most challenging and extreme environments imaginable for marine survey work. Frequently choked with constantly-shifting mélange ice at the sea surface and at risk from calving, surface vessels cannot operate safely proximal to the ice face. AUV (Autonomous Underwater Vehicle) technology provides an opportunity to survey in areas where surface vessels cannot. Operating well below the sea surface the AUV can operate without hindrance or danger to human operators. In addition, the AUV can be programmed to operate close to the seafloor at a constant altitude, enabling the finest-detail currently possible for acoustic seafloor mapping and consistent resolution irrespective of water depth. With these considerations in mind, we conducted a proof-of-concept survey of the Hubbard Glacier morainal bank in June, 2014. We utilized the Bluefin 9M, the smallest of their line of AUVs. Its size enabled deployment and recovery from a small charter fishing vessel well-suited to navigating through mélange-choked waters. The AUV's payload included a Klein UUV-3500 interferometric sonar (455/900 kHz), which enables acquisition of sidescan backscatter and swath bathymetry up to ~75 m to each side of the instrument from ~10 m altitude over the seabed, and sensors for measuring conductivity, temperature, depth (CTD) and optical backscatter (OBS). Although our operations were shortened due to an unfortunate failure in the sonar electronics, sufficient data were collected along the morainal bank to clearly prove the viability of AUV operations in this harsh environment. The data provide centimeter-scale seafloor detail close to the

  7. A semi-analytical model for the prediction of underwater noise from offshore pile driving

    NASA Astrophysics Data System (ADS)

    Tsouvalas, A.; Metrikine, A. V.

    2013-06-01

    Underwater noise from offshore pile driving gained considerable attention in recent years mainly due to the large scale construction of offshore wind farms. The most common foundation type of a wind turbine is a monopile, upon which the wind tower rests. The pile is driven into place with the help of hydraulic hammers. During the hammering of the pile, high levels of noise are generated which are known to produce deleterious effects on both mammals and fish. In this work, a linear semi-analytical model is developed for predicting the levels of underwater noise for a wide range of system parameters. The model incorporates all major parts of the system. The hydraulic hammer is substituted by an external force, the pile is described as a thin circular cylindrical shell, the water is modelled as a compressible fluid and the water-saturated seabed is defined by distributed springs and dashpots in all directions. The solution of the coupled vibroacoustic problem is based on the representation of the response of the complete system on the modal basis of the in vacuo shell structure. The influence that the inter-modal coupling, the choice of the soil parameters and the acoustic impedance of the seabed have on the generated noise levels is studied in the frequency domain. Strong and weak points of the present model are discussed on the basis of a comparison with a set of available experimental data. The obtained results show the capability of the model to predict the underwater noise levels both qualitatively and quantitatively.

  8. Modeling and Control Strategies for Autonomous Robotic Systems

    DTIC Science & Technology

    1991-12-23

    Robotic Systems 12 PERSONAL AUTHOR(S) Roger W. Brockett A]&. TYPE Of REPORT 113b. TIME COVERD 114 DATt__Of RE PVRT (Year- month, Day) S.PAGE COUNT Final...NO. ACCESSION NO Reseaich Triangle Park, NC 27709-2211I I 11 TITLE (ir-’-4 Cae-unrv Canmuicauon) Modeling and Control Strategies for Autonomous

  9. Underwater Sound Propagation Modeling Methods for Predicting Marine Animal Exposure.

    PubMed

    Hamm, Craig A; McCammon, Diana F; Taillefer, Martin L

    2016-01-01

    The offshore exploration and production (E&P) industry requires comprehensive and accurate ocean acoustic models for determining the exposure of marine life to the high levels of sound used in seismic surveys and other E&P activities. This paper reviews the types of acoustic models most useful for predicting the propagation of undersea noise sources and describes current exposure models. The severe problems caused by model sensitivity to the uncertainty in the environment are highlighted to support the conclusion that it is vital that risk assessments include transmission loss estimates with statistical measures of confidence.

  10. A potential flow based flight simulator for an underwater glider

    NASA Astrophysics Data System (ADS)

    Phoemsapthawee, Surasak; Le Boulluec, Marc; Laurens, Jean-Marc; Deniset, François

    2013-03-01

    Underwater gliders are recent innovative types of autonomous underwater vehicles (AUVs) used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the change of altitude, they use the hydrodynamic forces developed by their wings to move forward. Their flights are controlled by changing the position of their centers of gravity and their buoyancy to adjust their trim and heel angles. For better flight control, the understanding of the hydrodynamic behavior and the flight mechanics of the underwater glider is necessary. A 6-DOF motion simulator is coupled with an unsteady potential flow model for this purpose. In some specific cases, the numerical study demonstrates that an inappropriate stabilizer dimension can cause counter-steering behavior. The simulator can be used to improve the automatic flight control. It can also be used for the hydrodynamic design optimization of the devices.

  11. Modeling the flow regime near the source in underwater gas releases

    NASA Astrophysics Data System (ADS)

    Premathilake, Lakshitha T.; Yapa, Poojitha D.; Nissanka, Indrajith D.; Kumarage, Pubudu

    2016-12-01

    Recent progress in calculating gas bubble sizes in a plume, based on phenomenological approaches using the release conditions is a significant improvement to make the gas plume models self-reliant. Such calculations require details of conditions Near the Source of Plume (NSP); (i.e. the plume/jet velocity and radius near the source), which inspired the present work. Determining NSP conditions for gas plumes are far more complex than that for oil plumes due to the substantial density difference between gas and water. To calculate NSP conditions, modeling the early stage of the plume is important. A novel method of modeling the early stage of an underwater gas release is presented here. Major impact of the present work is to define the correct NSP conditions for underwater gas releases, which is not possible with available methods as those techniques are not based on the physics of flow region near the source of the plume/jet. We introduce super Gaussian profiles to model the density and velocity variations of the early stages of plume, coupled with the laws of fluid mechanics to define profile parameters. This new approach, models the velocity profile variation from near uniform, across the section at the release point to Gaussian some distance away. The comparisons show that experimental data agrees well with the computations.

  12. Underwater Blast Experiments and Modeling for Shock Mitigation

    SciTech Connect

    Glascoe, L; McMichael, L; Vandersall, K; Margraf, J

    2010-03-07

    A simple but novel mitigation concept to enforce standoff distance and reduce shock loading on a vertical, partially-submerged structure is evaluated using scaled aquarium experiments and numerical modeling. Scaled, water tamped explosive experiments were performed using three gallon aquariums. The effectiveness of different mitigation configurations, including air-filled media and an air gap, is assessed relative to an unmitigated detonation using the same charge weight and standoff distance. Experiments using an air-filled media mitigation concept were found to effectively dampen the explosive response of the aluminum plate and reduce the final displacement at plate center by approximately half. The finite element model used for the initial experimental design compares very well to the experimental DIC results both spatially and temporally. Details of the experiment and finite element aquarium models are described including the boundary conditions, Eulerian and Lagrangian techniques, detonation models, experimental design and test diagnostics.

  13. Comparison of Numerical Models for Computing Underwater Light Fields

    DTIC Science & Technology

    1994-04-01

    L is an analytic process, and thus there are body. Depth integration of the Riccati equations (by no Monte Carlo fluctuations in the computed radi - a...1)gj(T) C. Model MCI [ Monte Carlo (Gordon)] i=m This model simulates radiative transfer in both the ( M - i)! ocean and the atmosphere, as coupled...Kattawar and C. Adams, " Radiative transfer in spherical (1974). shell atmospheres. II. asymmetric phase functions ," Icarus 38. R. Stavn and A

  14. Review of Numerical Models in Underwater Acoustics, Including Recently Developed Fast-Field Program,

    DTIC Science & Technology

    1984-12-15

    scope of bringing together researchers in different fields of wave propagation (electromagnetics, optics , seismics, underwater acoustics) to exchange...discussed in this paper. A more detailed description can be found in references ə-10>. The starting point for all the models is the wave equation for a...harmonic point source with time dppendence exp(-iwt), V2*(x’yz) + * ] (x,Y,z) = -6(x-Xo)6(y-yo)6(z-zo ) (1) * *exp(-iwt) (2) At any point (x,y,z) in

  15. Modeling and underwater characterization of cymbal transducers and arrays.

    PubMed

    Zhang, J; Hladky-Hennion, A C; Hughes, W J; Newnham, R E

    2001-03-01

    The cymbal is a miniaturized class V flextensional transducer that was developed for potential use as a shallow water sound projector and receiver. Single elements are characterized by high Q, low efficiency, and medium power output capability. Its low cost and thin profile allow the transducer to be assembled into large flexible arrays. Efforts were made to model both single element and transducer arrays by coupling finite element analysis (ATILA) and the integral equation formulation (EQI). The pressure and velocity distributions on the surface elements were calculated by ATILA and later used with EQI to calculate the far field properties of the transducer element and arrays. It eliminates the mesh of the fluid domain and makes the 3-D model of a transducer possible. Three-dimensional models of a cymbal transducer and a 3 x 3 cymbal array were developed in the modeling. Very good agreement was obtained between modeling and measurement for single element transducers. By coupling finite element analysis with the integral equation method using boundary elements, acoustic interaction effects were taken into account. Reasonable agreement was obtained between calculation and measurement for a 3 x 3 array.

  16. Modeling the Behavior of an Underwater Acoustic Relative Positioning System Based on Complementary Set of Sequences

    PubMed Central

    Aparicio, Joaquín; Jiménez, Ana; Álvarez, Fernando J.; Ureña, Jesús; De Marziani, Carlos; Diego, Cristina

    2011-01-01

    The great variability usually found in underwater media makes modeling a challenging task, but helpful for better understanding or predicting the performance of future deployed systems. In this work, an underwater acoustic propagation model is presented. This model obtains the multipath structure by means of the ray tracing technique. Using this model, the behavior of a relative positioning system is presented. One of the main advantages of relative positioning systems is that only the distances between all the buoys are needed to obtain their positions. In order to obtain the distances, the propagation times of acoustic signals coded by Complementary Set of Sequences (CSS) are used. In this case, the arrival instants are obtained by means of correlation processes. The distances are then used to obtain the position of the buoys by means of the Multidimensional Scaling Technique (MDS). As an early example of an application using this relative positioning system, a tracking of the position of the buoys at different times is performed. With this tracking, the surface current of a particular region could be studied. The performance of the system is evaluated in terms of the distance from the real position to the estimated one. PMID:22247661

  17. Automatically calibrating admittances in KATE's autonomous launch operations model

    NASA Astrophysics Data System (ADS)

    Morgan, Steve

    1992-09-01

    This report documents a 1000-line Symbolics LISP program that automatically calibrates all 15 fluid admittances in KATE's Autonomous Launch Operations (ALO) model. (KATE is Kennedy Space Center's Knowledge-based Autonomous Test Engineer, a diagnosis and repair expert system created for use on the Space Shuttle's various fluid flow systems.) As a new KATE application, the calibrator described here breaks new ground for KSC's Artificial Intelligence Lab by allowing KATE to both control and measure the hardware she supervises. By automating a formerly manual process, the calibrator: (1) saves the ALO model builder untold amounts of labor; (2) enables quick repairs after workmen accidently adjust ALO's hand valves; and (3) frees the modeler to pursue new KATE applications that previously were too complicated. Also reported are suggestions for enhancing the program: (1) to calibrate ALO's TV cameras, pumps, and sensor tolerances; and (2) to calibrate devices in other KATE models, such as the shuttle's LOX and Environment Control System (ECS).

  18. Automatically calibrating admittances in KATE's autonomous launch operations model

    NASA Technical Reports Server (NTRS)

    Morgan, Steve

    1992-01-01

    This report documents a 1000-line Symbolics LISP program that automatically calibrates all 15 fluid admittances in KATE's Autonomous Launch Operations (ALO) model. (KATE is Kennedy Space Center's Knowledge-based Autonomous Test Engineer, a diagnosis and repair expert system created for use on the Space Shuttle's various fluid flow systems.) As a new KATE application, the calibrator described here breaks new ground for KSC's Artificial Intelligence Lab by allowing KATE to both control and measure the hardware she supervises. By automating a formerly manual process, the calibrator: (1) saves the ALO model builder untold amounts of labor; (2) enables quick repairs after workmen accidently adjust ALO's hand valves; and (3) frees the modeler to pursue new KATE applications that previously were too complicated. Also reported are suggestions for enhancing the program: (1) to calibrate ALO's TV cameras, pumps, and sensor tolerances; and (2) to calibrate devices in other KATE models, such as the shuttle's LOX and Environment Control System (ECS).

  19. Modeling and validation of polyurethane based passive underwater acoustic absorber.

    PubMed

    Jayakumari, V G; Shamsudeen, Rahna K; Ramesh, R; Mukundan, T

    2011-08-01

    The acoustic behavior of an acoustically transparent polyurethane and an interpenetrating polymer network of polyurethane with polydimethyl siloxane were studied using dynamic mechanical analysis, finite element modeling, and experimental evaluation of acoustic properties in a water-filled pulse tube setup. Dynamic mechanical measurements in the temperature range -50 °C to +70 °C were carried out, and the data were used for time temperature superposition to generate material behavior at high frequencies. These inputs were used for modeling the acoustic behavior of these materials using ATILA, which is a commercial finite element code, capable of computing transmission and reflection characteristics of materials. From this data, absorption characteristics were computed. The results were compared with the experimental results obtained using a water-filled pulse tube facility.

  20. An Optical Model for Estimating the Underwater Light Field from Remote Sensing

    NASA Technical Reports Server (NTRS)

    Liu, Cheng-Chien; Miller, Richard L.

    2002-01-01

    A model of the wavelength-integrated scalar irradiance for a vertically homogeneous water column is developed. It runs twenty thousand times faster than simulations obtained using full Hydrolight code and limits the percentage error to less than 3.7%. Both the distribution of incident sky radiance and a wind-roughened surface are integrated in the model. Our model removes common limitations of earlier models and can be applied to waters with any composition of the inherent optical properties. Implementation of this new model, as well as the ancillary information required for processing global-scale satellite data, is discussed. This new model is fast, accurate, and flexible and therefore provides important information of the underwater light field from remote sensing.

  1. D Models Comparison of Complex Shell in Underwater and Dry Environments

    NASA Astrophysics Data System (ADS)

    Troisi, S.; Del Pizzo, S.; Gaglione, S.; Miccio, A.; Testa, R. L.

    2015-04-01

    In marine biology the shape, morphology, texture and dimensions of the shells and organisms like sponges and gorgonians are very important parameters. For example, a particular type of gorgonian grows every year only few millimeters; this estimation was conducted without any measurement instrument but it has been provided after successive observational studies, because this organism is very fragile: the contact could compromise its structure and outliving. Non-contact measurement system has to be used to preserve such organisms: the photogrammetry is a method capable to assure high accuracy without contact. Nevertheless, the achievement of a 3D photogrammetric model of complex object (as gorgonians or particular shells) is a challenge in normal environments, either with metric camera or with consumer camera. Indeed, the successful of automatic target-less image orientation and the image matching algorithms is strictly correlated to the object texture properties and of camera calibration quality as well. In the underwater scenario, the environment conditions strongly influence the results quality; in particular, water's turbidity, the presence of suspension, flare and other optical aberrations decrease the image quality reducing the accuracy and increasing the noise on the 3D model. Furthermore, seawater density variability influences its refraction index and consequently the interior orientation camera parameters. For this reason, the camera calibration has to be performed in the same survey conditions. In this paper, a comparison between the 3D models of a Charonia Tritonis shell are carried out through surveys conducted both in dry and underwater environments.

  2. Stereoscopic system for measuring particle trajectories past an underwater model

    NASA Astrophysics Data System (ADS)

    Liu, H.-T.; Weissman, Michael A.; White, Gary B.; Miner, G. E.; Gustafson, William T.

    1994-04-01

    A stereoscopic system was developed that integrates hardware and software components for image acquisition, digitization, processing, display, and measurements. The model-induced trajectories of nearly neutrally buoyant fluorescent particles, illuminated with a 15-W pulsed copper vapor laser, are tracked in a towing tank by stereoscopic time-lapse photography using two 35-mm cameras positioned at a 90-degree angle from the top and the side. A C program, HI, drives two data I/O boards hosted in a PC to set up the run parameters, control the operations of the laser and camera shutters, and acquire the stereo images. The photographic records are digitized and processed to derive the centroids of reference marks and particle images. The centroids are then fed into a Windows-based program, Track/3D, to perform image correlation, correction for image distortion, stereo conversion, stereoscopic display, and measurements. The display module incorporates a graphics library that drives a stereoscopic display adapter attached to a monitor; the stereogram must be viewed with polarizing glasses. Functions are available for image translation, rotation, zooming, and on- screen measurements. The velocity and acceleration components of the 3-D flow field induced by the model are derived from the trajectories, serving as a basis for whole-field stereoscopic quantitative flow visualization.

  3. Modeling of autonomic control in sleep-disordered breathing.

    PubMed

    Khoo, Michael C K

    2008-03-01

    There is ample evidence to support the notion that chronic exposure to repetitive episodes of interrupted breathing during sleep can lead to systemic hypertension, heart failure, myocardial infarction and stroke. Recent studies have suggested that abnormal autonomic control may be the common factor linking sleep-disordered breathing (SDB) to these cardiovascular diseases. We have developed a closed-loop minimal model that enables the delineation of the major physiological mechanisms responsible for changes in autonomic system function in SDB, and also forms the basis for a noninvasive technique that enables the early detection of cardiovascular control abnormalities. The model is "minimal" in the sense that all its parameters can be estimated through analysis of the data measured noninvasively from a single experimental procedure. Parameter estimation is enhanced by broadening the frequency content of the subject's ventilatory pattern, either through voluntary control of breathing or involuntary control using ventilator assistance. Although the original form of the model is linear and time-invariant, extensions of the model include the incorporation of nonlinear dynamics in the autonomic control of heart rate, and allowing the transfer functions of the model components to assume time-varying characteristics. The various versions of the model have been applied to different populations of subjects with SDB under different conditions (e.g. supine wakefulness, orthostatic stress, sleep). Our cumulative findings suggest that the minimal model approach provides a more sensitive means of detecting abnormalities in autonomic cardiovascular control in SDB, compared to univariate analysis of heart rate variability or blood pressure variability.

  4. Nonlinear interaction between underwater explosion bubble and structure based on fully coupled model

    NASA Astrophysics Data System (ADS)

    Zhang, A. M.; Wu, W. B.; Liu, Y. L.; Wang, Q. X.

    2017-08-01

    The interaction between an underwater explosion bubble and an elastic-plastic structure is a complex transient process, accompanying violent bubble collapsing, jet impact, penetration through the bubble, and large structural deformation. In the present study, the bubble dynamics are modeled using the boundary element method and the nonlinear transient structural response is modeled using the explicit finite element method. A new fully coupled 3D model is established through coupling the equations for the state variables of the fluid and structure and solving them as a set of coupled linear algebra equations. Based on the acceleration potential theory, the mutual dependence between the hydrodynamic load and the structural motion is decoupled. The pressure distribution in the flow field is calculated with the Bernoulli equation, where the partial derivative of the velocity potential in time is calculated using the boundary integral method to avoid numerical instabilities. To validate the present fully coupled model, the experiments of small-scale underwater explosion near a stiffened plate are carried out. High-speed imaging is used to capture the bubble behaviors and strain gauges are used to measure the strain response. The numerical results correspond well with the experimental data, in terms of bubble shapes and structural strain response. By both the loosely coupled model and the fully coupled model, the interaction between a bubble and a hollow spherical shell is studied. The bubble patterns vary with different parameters. When the fully coupled model and the loosely coupled model are advanced with the same time step, the error caused by the loosely coupled model becomes larger with the coupling effect becoming stronger. The fully coupled model is more stable than the loosely coupled model. Besides, the influences of the internal fluid on the dynamic response of the spherical shell are studied. At last, the case that the bubble interacts with an air

  5. Underwater measurements and modeling of a sonic boom.

    PubMed

    Desharnais, Francine; Chapman, David M F

    2002-01-01

    During a sea trial on the Scotian Shelf, acoustic signals from a sonic boom were recorded on 11 hydrophones of a vertical array. The array spanned the lower 50 m of the water column above a sand bank at 76 m water depth. The source of the sonic boom was deduced to be a Concorde supersonic airliner traveling at about Mach 2. The waterborne waveform was observed to decay as an evanescent wave below the sea surface, as expected. The calm weather (sea state 1) resulted in low ambient noise and low self-noise at the hydrophones, and good signal-to-noise ratio on the upper hydrophones; however, the decreased signal amplitude is more difficult to detect towards the lower part of the water column. The period of the observed waveform is of the order 0.23 s, corresponding to a peak frequency of about 3 Hz. The shape of the measured waveform differs noticeably from the theoretical N-shape waveform predicted with Sawyers' theory [J. Acoust. Soc. Am. 44, 523-524 (1968)]. A simple shallow-ocean geoacoustic model suggests that this effect may be caused in part by seismo-acoustic interaction of the infrasonic waves with the elastic sediments that form the seabed.

  6. Design and implementation of an underwater sound recording device.

    PubMed

    Martinez, Jayson J; Myers, Josh R; Carlson, Thomas J; Deng, Z Daniel; Rohrer, John S; Caviggia, Kurt A; Woodley, Christa M; Weiland, Mark A

    2011-01-01

    To monitor the underwater sound and pressure waves generated by anthropogenic activities such as underwater blasting and pile driving, an autonomous system was designed to record underwater acoustic signals. The underwater sound recording device (USR) allows for connections of two hydrophones or other dynamic pressure sensors, filters high frequency noise out of the collected signals, has a gain that can be independently set for each sensor, and allows for 2 h of data collection. Two versions of the USR were created: a submersible model deployable to a maximum depth of 300 m, and a watertight but not fully submersible model. Tests were performed on the USR in the laboratory using a data acquisition system to send single-frequency sinusoidal voltages directly to each component. These tests verified that the device operates as designed and performs as well as larger commercially available data acquisition systems, which are not suited for field use. On average, the designed gain values differed from the actual measured gain values by about 0.35 dB. A prototype of the device was used in a case study to measure blast pressures while investigating the effect of underwater rock blasting on juvenile Chinook salmon and rainbow trout. In the case study, maximum positive pressure from the blast was found to be significantly correlated with frequency of injury for individual fish. The case study also demonstrated that the device withstood operation in harsh environments, making it a valuable tool for collecting field measurements.

  7. Design and Implementation of an Underwater Sound Recording Device

    PubMed Central

    Martinez, Jayson J.; Myers, Josh R.; Carlson, Thomas J.; Deng, Z. Daniel; Rohrer, John S.; Caviggia, Kurt A.; Woodley, Christa M.; Weiland, Mark A.

    2011-01-01

    To monitor the underwater sound and pressure waves generated by anthropogenic activities such as underwater blasting and pile driving, an autonomous system was designed to record underwater acoustic signals. The underwater sound recording device (USR) allows for connections of two hydrophones or other dynamic pressure sensors, filters high frequency noise out of the collected signals, has a gain that can be independently set for each sensor, and allows for 2 h of data collection. Two versions of the USR were created: a submersible model deployable to a maximum depth of 300 m, and a watertight but not fully submersible model. Tests were performed on the USR in the laboratory using a data acquisition system to send single-frequency sinusoidal voltages directly to each component. These tests verified that the device operates as designed and performs as well as larger commercially available data acquisition systems, which are not suited for field use. On average, the designed gain values differed from the actual measured gain values by about 0.35 dB. A prototype of the device was used in a case study to measure blast pressures while investigating the effect of underwater rock blasting on juvenile Chinook salmon and rainbow trout. In the case study, maximum positive pressure from the blast was found to be significantly correlated with frequency of injury for individual fish. The case study also demonstrated that the device withstood operation in harsh environments, making it a valuable tool for collecting field measurements. PMID:22164089

  8. CFD modeling of a laboratory-scale underwater explosion created by a spark gap source

    NASA Astrophysics Data System (ADS)

    Esplin, J. James; Kinzel, Michael P.; Kim, Benjamin; Culver, R. Lee

    2015-11-01

    Underwater explosions contain complex physical phenomena that can be difficult to observe. As large-scale tests are expensive, most researchers investigate the physical phenomena using laboratory-scale explosions with hopes that the salient physical phenomena remain similar. Most of the laboratory-scale tests use small amounts of chemical explosive as the explosive source, which have been examined using computational fluid dynamics (CFD) modeling at both large and small-scale. Other tests use a spark gap source (sparker) as the explosive source, which act similarly to chemical explosives on a small scale. Few studies have applied CFD to spark gap sources used to model underwater explosions, and fewer still have dealt with the differences between chemical explosions and spark gap sources. This work will demonstrate CFD simulations for a spark gap source discharged near a free surface. The simulation uses a compressible medium including both a gas and liquid and aims to predict the transient bubble motion and pressure field. The simulations are validated against experimental data. Work supported by the ONR Naval Undersea Research Program.

  9. A small-scale comparison of Iceland scallop size distributions obtained from a camera based autonomous underwater vehicle and dredge survey.

    PubMed

    Singh, Warsha; Örnólfsdóttir, Erla B; Stefansson, Gunnar

    2014-01-01

    An approach is developed to estimate size of Iceland scallop shells from AUV photos. A small-scale camera based AUV survey of Iceland scallops was conducted at a defined site off West Iceland. Prior to height estimation of the identified shells, the distortions introduced by the vehicle orientation and the camera lens were corrected. The average AUV pitch and roll was 1.3 and 2.3 deg that resulted in <2% error in ground distance rendering these effects negligible. A quadratic polynomial model was identified for lens distortion correction. This model successfully predicted a theoretical grid from a frame photographed underwater, representing the inherent lens distortion. The predicted shell heights were scaled for the distance from the bottom at which the photos were taken. This approach was validated by height estimation of scallops of known sizes. An underestimation of approximately 0.5 cm was seen, which could be attributed to pixel error, where each pixel represented 0.24 x 0.27 cm. After correcting for this difference the estimated heights ranged from 3.8-9.3 cm. A comparison of the height-distribution from a small-scale dredge survey carried out in the vicinity showed non-overlapping peaks in size distribution, with scallops of a broader size range visible in the AUV survey. Further investigations are necessary to evaluate any underlying bias and to validate how representative these surveys are of the true population. The low resolution images made identification of smaller scallops difficult. Overall, the observations of very few small scallops in both surveys could be attributed to low recruitment levels in the recent years due to the known scallop parasite outbreak in the region.

  10. A Small-Scale Comparison of Iceland Scallop Size Distributions Obtained from a Camera Based Autonomous Underwater Vehicle and Dredge Survey

    PubMed Central

    Singh, Warsha; Örnólfsdóttir, Erla B.; Stefansson, Gunnar

    2014-01-01

    An approach is developed to estimate size of Iceland scallop shells from AUV photos. A small-scale camera based AUV survey of Iceland scallops was conducted at a defined site off West Iceland. Prior to height estimation of the identified shells, the distortions introduced by the vehicle orientation and the camera lens were corrected. The average AUV pitch and roll was and deg that resulted in error in ground distance rendering these effects negligible. A quadratic polynomial model was identified for lens distortion correction. This model successfully predicted a theoretical grid from a frame photographed underwater, representing the inherent lens distortion. The predicted shell heights were scaled for the distance from the bottom at which the photos were taken. This approach was validated by height estimation of scallops of known sizes. An underestimation of approximately cm was seen, which could be attributed to pixel error, where each pixel represented cm. After correcting for this difference the estimated heights ranged from cm. A comparison of the height-distribution from a small-scale dredge survey carried out in the vicinity showed non-overlapping peaks in size distribution, with scallops of a broader size range visible in the AUV survey. Further investigations are necessary to evaluate any underlying bias and to validate how representative these surveys are of the true population. The low resolution images made identification of smaller scallops difficult. Overall, the observations of very few small scallops in both surveys could be attributed to low recruitment levels in the recent years due to the known scallop parasite outbreak in the region. PMID:25303243

  11. Underwater birth.

    PubMed

    Simpson, Kathleen Rice

    2013-01-01

    To determine potential risks and/or benefits of underwater birth for mother and infant. The PubMed, Cochrane Library, EMBASE, and CINAHL online databases were searched for relevant English language articles related to research about underwater birth published from 1966 to April 2013. Reference lists of articles retrieved were reviewed to identify additional potentially pertinent publications. Two randomized controlled trials comparing underwater birth to traditional birth ("on land") were identified and served as the primary focus of the analysis. One systematic review of water immersion during labor and birth, one systematic review of neonatal risks of underwater birth, and case reports of neonatal morbidity after underwater birth were also identified. Guidelines regarding underwater birth from professional organizations were reviewed. Data from the two randomized controlled trials were extracted and organized under the following headings: author, year, setting, country, study design, sample size, participants, outcomes, findings and comments. Systematic reviews, case reports, and guidelines from professional organizations were summarized. Research findings and guidelines from professional associations were evaluated regarding potential risks and benefits of underwater birth to the mother and infant. Only two randomized controlled trials comparing underwater birth to birth on land have been published. Results suggest minimal benefit of underwater birth to the mother and no benefit to the infant. Both studies were underpowered to adequately evaluate risk of neonatal harm; however, a number of cases of neonatal morbidity have been reported. Based on these findings, underwater birth requires more rigorous study. In the United States, underwater birth is not supported by the American Academy of Pediatrics or the American College of Obstetricians and Gynecologists outside the context of a randomized controlled trial. © 2013 AWHONN, the Association of Women's Health

  12. An advanced terrain modeler for an autonomous planetary rover

    NASA Technical Reports Server (NTRS)

    Hunter, E. L.

    1980-01-01

    A roving vehicle capable of autonomously exploring the surface of an alien world is under development and an advanced terrain modeler to characterize the possible paths of the rover as hazardous or safe is presented. This advanced terrain modeler has several improvements over the Troiani modeler that include: a crosspath analysis, better determination of hazards on slopes, and methods for dealing with missing returns at the extremities of the sensor field. The results from a package of programs to simulate the roving vehicle are then examined and compared to results from the Troiani modeler.

  13. Autonomous Navigation of Small Uavs Based on Vehicle Dynamic Model

    NASA Astrophysics Data System (ADS)

    Khaghani, M.; Skaloud, J.

    2016-03-01

    This paper presents a novel approach to autonomous navigation for small UAVs, in which the vehicle dynamic model (VDM) serves as the main process model within the navigation filter. The proposed method significantly increases the accuracy and reliability of autonomous navigation, especially for small UAVs with low-cost IMUs on-board. This is achieved with no extra sensor added to the conventional INS/GNSS setup. This improvement is of special interest in case of GNSS outages, where inertial coasting drifts very quickly. In the proposed architecture, the solution to VDM equations provides the estimate of position, velocity, and attitude, which is updated within the navigation filter based on available observations, such as IMU data or GNSS measurements. The VDM is also fed with the control input to the UAV, which is available within the control/autopilot system. The filter is capable of estimating wind velocity and dynamic model parameters, in addition to navigation states and IMU sensor errors. Monte Carlo simulations reveal major improvements in navigation accuracy compared to conventional INS/GNSS navigation system during the autonomous phase, when satellite signals are not available due to physical obstruction or electromagnetic interference for example. In case of GNSS outages of a few minutes, position and attitude accuracy experiences improvements of orders of magnitude compared to inertial coasting. It means that during such scenario, the position-velocity-attitude (PVA) determination is sufficiently accurate to navigate the UAV to a home position without any signal that depends on vehicle environment.

  14. Google™ underwater

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-10-01

    The first underwater panoramic images were added to Google Maps™, the company announced on 25 September. This first “underwater Street View collection,” launched in partnership with the Caitlin Seaview Survey, provides people with the opportunity to “become the next virtual Jacques Cousteau.” For more information, see: maps.google.com/ocean.

  15. Compressive line sensing underwater imaging system

    NASA Astrophysics Data System (ADS)

    Ouyang, B.; Dalgleish, F. R.; Vuorenkoski, A. K.; Caimi, F. M.; Britton, W.

    2013-05-01

    Compressive sensing (CS) theory has drawn great interest and led to new imaging techniques in many different fields. In recent years, the FAU/HBOI OVOL has conducted extensive research to study the CS based active electro-optical imaging system in the scattering medium such as the underwater environment. The unique features of such system in comparison with the traditional underwater electro-optical imaging system are discussed. Building upon the knowledge from the previous work on a frame based CS underwater laser imager concept, more advantageous for hover-capable platforms such as the Hovering Autonomous Underwater Vehicle (HAUV), a compressive line sensing underwater imaging (CLSUI) system that is more compatible with the conventional underwater platforms where images are formed in whiskbroom fashion, is proposed in this paper. Simulation results are discussed.

  16. Singular Value Spectrum Based Detection and Estimation of Non-Stationary Underwater Acoustic Signals and Their Statistical Modelling by Approximation.

    DTIC Science & Technology

    1992-03-01

    APPROXIMATION March 1992 Professors Nenad M Marinovic and Leonid Roytman Department of Electrical Engineering The City College of The City University...Non-Stationary . Underwater Acous’ic Signals and Their Statistical Modelling by Approximation W -,d, s r Nenad M. Marinovic and Leonid Roytman

  17. A Collaborative Secure Localization Algorithm Based on Trust Model in Underwater Wireless Sensor Networks.

    PubMed

    Han, Guangjie; Liu, Li; Jiang, Jinfang; Shu, Lei; Rodrigues, Joel J P C

    2016-02-16

    Localization is one of the hottest research topics in Underwater Wireless Sensor Networks (UWSNs), since many important applications of UWSNs, e.g., event sensing, target tracking and monitoring, require location information of sensor nodes. Nowadays, a large number of localization algorithms have been proposed for UWSNs. How to improve location accuracy are well studied. However, few of them take location reliability or security into consideration. In this paper, we propose a Collaborative Secure Localization algorithm based on Trust model (CSLT) for UWSNs to ensure location security. Based on the trust model, the secure localization process can be divided into the following five sub-processes: trust evaluation of anchor nodes, initial localization of unknown nodes, trust evaluation of reference nodes, selection of reference node, and secondary localization of unknown node. Simulation results demonstrate that the proposed CSLT algorithm performs better than the compared related works in terms of location security, average localization accuracy and localization ratio.

  18. A Collaborative Secure Localization Algorithm Based on Trust Model in Underwater Wireless Sensor Networks

    PubMed Central

    Han, Guangjie; Liu, Li; Jiang, Jinfang; Shu, Lei; Rodrigues, Joel J.P.C.

    2016-01-01

    Localization is one of the hottest research topics in Underwater Wireless Sensor Networks (UWSNs), since many important applications of UWSNs, e.g., event sensing, target tracking and monitoring, require location information of sensor nodes. Nowadays, a large number of localization algorithms have been proposed for UWSNs. How to improve location accuracy are well studied. However, few of them take location reliability or security into consideration. In this paper, we propose a Collaborative Secure Localization algorithm based on Trust model (CSLT) for UWSNs to ensure location security. Based on the trust model, the secure localization process can be divided into the following five sub-processes: trust evaluation of anchor nodes, initial localization of unknown nodes, trust evaluation of reference nodes, selection of reference node, and secondary localization of unknown node. Simulation results demonstrate that the proposed CSLT algorithm performs better than the compared related works in terms of location security, average localization accuracy and localization ratio. PMID:26891300

  19. The Trans-Contextual Model of Autonomous Motivation in Education

    PubMed Central

    Hagger, Martin S.; Chatzisarantis, Nikos L. D.

    2015-01-01

    The trans-contextual model outlines the processes by which autonomous motivation toward activities in a physical education context predicts autonomous motivation toward physical activity outside of school, and beliefs about, intentions toward, and actual engagement in, out-of-school physical activity. In the present article, we clarify the fundamental propositions of the model and resolve some outstanding conceptual issues, including its generalizability across multiple educational domains, criteria for its rejection or failed replication, the role of belief-based antecedents of intentions, and the causal ordering of its constructs. We also evaluate the consistency of model relationships in previous tests of the model using path-analytic meta-analysis. The analysis supported model hypotheses but identified substantial heterogeneity in the hypothesized relationships across studies unattributed to sampling and measurement error. Based on our meta-analysis, future research needs to provide further replications of the model in diverse educational settings beyond physical education and test model hypotheses using experimental methods. PMID:27274585

  20. A non-autonomous stochastic predator-prey model.

    PubMed

    Buonocore, Aniello; Caputo, Luigia; Pirozzi, Enrica; Nobile, Amelia G

    2014-04-01

    The aim of this paper is to consider a non-autonomous predator-prey-like system, with a Gompertz growth law for the prey. By introducing random variations in both prey birth and predator death rates, a stochastic model for the predator-prey-like system in a random environment is proposed and investigated. The corresponding Fokker-Planck equation is solved to obtain the joint probability density for the prey and predator populations and the marginal probability densities. The asymptotic behavior of the predator-prey stochastic model is also analyzed.

  1. A modified resistance equation for modeling underwater spark discharge with salinity and high pressure conditions

    SciTech Connect

    Zhao, Pengfei; Roy, Subrata

    2014-05-07

    This work investigates the performance of underwater spark discharge relating to bubble growth and decay under high pressure and with salinity conditions by introducing a modified form of the resistance equation. Here, we study salinity influence on circuit parameters by fitting the experimental data for which gap resistance is much larger in conductive water than in dielectric water. Accordingly, the resistance equation is modified by considering the influence of both plasma and its surrounding liquid. Thermal radiation effect of the bubble is also studied by comparing two different radiation models. Numerical results predict a larger bubble pressure for saline water but a reduced size and a smaller bubble cycle at a greater water depth. Such study may be useful in many saltwater applications, including that for deep sea conditions.

  2. Software architecture of biomimetic underwater vehicle

    NASA Astrophysics Data System (ADS)

    Praczyk, Tomasz; Szymak, Piotr

    2016-05-01

    Autonomous underwater vehicles are vehicles that are entirely or partly independent of human decisions. In order to obtain operational independence, the vehicles have to be equipped with a specialized software. The main task of the software is to move the vehicle along a trajectory with collision avoidance. Moreover, the software has also to manage different devices installed on the vehicle board, e.g. to start and stop cameras, sonars etc. In addition to the software embedded on the vehicle board, the software responsible for managing the vehicle by the operator is also necessary. Its task is to define mission of the vehicle, to start, to stop the mission, to send emergency commands, to monitor vehicle parameters, and to control the vehicle in remotely operated mode. An important objective of the software is also to support development and tests of other software components. To this end, a simulation environment is necessary, i.e. simulation model of the vehicle and all its key devices, the model of the sea environment, and the software to visualize behavior of the vehicle. The paper presents architecture of the software designed for biomimetic autonomous underwater vehicle (BAUV) that is being constructed within the framework of the scientific project financed by Polish National Center of Research and Development.

  3. Cross Body Thruster Control and Modeling of a Body of Revolution Autonomous Underwater Vehicle

    DTIC Science & Technology

    2011-03-01

    FIGURES Figure 1. Da Vinci’s sketch of a manned submersible, upper-left, [1] and diving rig , right, [2] circa 1500...Leonardo da Vinci envisioned submersible troop transports, assault craft, and diving rigs in the early sixteenth century. Figure 1. Da...Vinci’s sketch of a manned submersible, upper-left, [1] and diving rig , right, [2] circa 1500. Ultimately, the idea remained on paper only, as full

  4. Model Based Design and Verification of a Rapid Dive Controller for an Autonomous Underwater Vehicle

    DTIC Science & Technology

    1989-03-01

    S,NS,0.O5): YHA’r=FILP(SD,U,XO): / OBIAS IS ADDED TO RESPONSE OF PITCH RATE OF MAGNITUDE DELTA QBIAS=DELTAO*ONES(250,1); ZB1AS=DELTAZ*ONES(250,1); YHAT...BB;CC DD]; V=EIG(AA); SD=DISCRETlZE(S,NSO0.OS); YHAT=FILP(SD,U,XO); // QBIAS IS ADDED TO RESPONSE OF PITCH RATE //OF MAGNITUDE DELTA OBIAS =DELTAQ*ONES

  5. Trim Calculation Methods for a Dynamical Model of the REMUS 100 Autonomous Underwater Vehicle

    DTIC Science & Technology

    2011-08-01

    for sway & rolling motion -1.93 kg.m.rad-2 Mrp Pitch mom. coeff. for yaw & rolling motion 4.86 kg.m2.rad-2 Nur Yaw mom. coeff. for forward and yawing...Xqq Xvr Xrr Yvv Yrr Yuv Yur Ywp Ypq Yuudr Zww Zqq Zuw Zuq Zvp Zrp Zuuds Kpp Mww Mqq Muw Muq Mvp Mrp Muuds Nvv Nrr Nuv Nur Nwp Npq Nuudr Ndr Kpdot...Zvp Zrp Zuuds Kpp Mww Mqq Muw Muq Mvp Mrp Muuds Nvv Nrr Nuv Nur Nwp Npq Nuudr Ndr Kpdot Tnn Qnn df0 df nd global V % Mass Matrix M(1,1

  6. A Study of Model Based Maneuvering Controls for Autonomous Underwater Vehicles

    DTIC Science & Technology

    1987-12-01

    relatively simple functions of the forward speed. Also, since the nominal path is associated with neither rotation nor cross-track or depth translation...modern multivariable system controls methods used in modern autopilot design. B. CLASSICAL CONTROL OF COURSE AND DEPTH Simple autopilots have long been of...principle, is simple , consisting of a sequence of stepwise control actions, yet knowledge of switching times for anything other than very low order

  7. Autonomous learning derived from experimental modeling of physical laws.

    PubMed

    Grabec, Igor

    2013-05-01

    This article deals with experimental description of physical laws by probability density function of measured data. The Gaussian mixture model specified by representative data and related probabilities is utilized for this purpose. The information cost function of the model is described in terms of information entropy by the sum of the estimation error and redundancy. A new method is proposed for searching the minimum of the cost function. The number of the resulting prototype data depends on the accuracy of measurement. Their adaptation resembles a self-organized, highly non-linear cooperation between neurons in an artificial NN. A prototype datum corresponds to the memorized content, while the related probability corresponds to the excitability of the neuron. The method does not include any free parameters except objectively determined accuracy of the measurement system and is therefore convenient for autonomous execution. Since representative data are generally less numerous than the measured ones, the method is applicable for a rather general and objective compression of overwhelming experimental data in automatic data-acquisition systems. Such compression is demonstrated on analytically determined random noise and measured traffic flow data. The flow over a day is described by a vector of 24 components. The set of 365 vectors measured over one year is compressed by autonomous learning to just 4 representative vectors and related probabilities. These vectors represent the flow in normal working days and weekends or holidays, while the related probabilities correspond to relative frequencies of these days. This example reveals that autonomous learning yields a new basis for interpretation of representative data and the optimal model structure.

  8. Autonomous Boolean modelling of developmental gene regulatory networks

    PubMed Central

    Cheng, Xianrui; Sun, Mengyang; Socolar, Joshua E. S.

    2013-01-01

    During early embryonic development, a network of regulatory interactions among genes dynamically determines a pattern of differentiated tissues. We show that important timing information associated with the interactions can be faithfully represented in autonomous Boolean models in which binary variables representing expression levels are updated in continuous time, and that such models can provide a direct insight into features that are difficult to extract from ordinary differential equation (ODE) models. As an application, we model the experimentally well-studied network controlling fly body segmentation. The Boolean model successfully generates the patterns formed in normal and genetically perturbed fly embryos, permits the derivation of constraints on the time delay parameters, clarifies the logic associated with different ODE parameter sets and provides a platform for studying connectivity and robustness in parameter space. By elucidating the role of regulatory time delays in pattern formation, the results suggest new types of experimental measurements in early embryonic development. PMID:23034351

  9. USE OF A LONG ENDURANCE SOLAR POWERED AUTONOMOUS UNDERWATER VEHICLE (SAUV II) TO MEASURE DISSOLVED OXYGEN CONCENTRATIONS IN GREENWICH BAY, RHODE ISLAND, USA

    EPA Science Inventory

    As hypoxic water masses increase worldwide in duration and extent due to coastal eutrophication, advanced technology water quality monitoring by autonomous vehicles can increase our capability to document and respond to these environmental perturbations. We evaluated the use of a...

  10. USE OF A LONG ENDURANCE SOLAR POWERED AUTONOMOUS UNDERWATER VEHICLE (SAUV II) TO MEASURE DISSOLVED OXYGEN CONCENTRATIONS IN GREENWICH BAY, RHODE ISLAND, USA

    EPA Science Inventory

    As hypoxic water masses increase worldwide in duration and extent due to coastal eutrophication, advanced technology water quality monitoring by autonomous vehicles can increase our capability to document and respond to these environmental perturbations. We evaluated the use of a...

  11. Vision Underwater.

    ERIC Educational Resources Information Center

    Levine, Joseph S.

    1980-01-01

    Provides information regarding underwater vision. Includes a discussion of optically important interfaces, increased eye size of organisms at greater depths, visual peculiarities regarding the habitat of the coastal environment, and various pigment visual systems. (CS)

  12. Vision Underwater.

    ERIC Educational Resources Information Center

    Levine, Joseph S.

    1980-01-01

    Provides information regarding underwater vision. Includes a discussion of optically important interfaces, increased eye size of organisms at greater depths, visual peculiarities regarding the habitat of the coastal environment, and various pigment visual systems. (CS)

  13. A new rate-dependent unidirectional composite model - Application to panels subjected to underwater blast

    NASA Astrophysics Data System (ADS)

    Wei, Xiaoding; de Vaucorbeil, Alban; Tran, Phuong; Espinosa, Horacio D.

    2013-06-01

    In this study, we developed a finite element fluid-structure interaction model to understand the deformation and failure mechanisms of both monolithic and sandwich composite panels. A new failure criterion that includes strain-rate effects was formulated and implemented to simulate different damage modes in unidirectional glass fiber/matrix composites. The laminate model uses Hashin's fiber failure criterion and a modified Tsai-Wu matrix failure criterion. The composite moduli are degraded using five damage variables, which are updated in the post-failure regime by means of a linear softening law governed by an energy release criterion. A key feature in the formulation is the distinction between fiber rupture and pull-out by introducing a modified fracture toughness, which varies from a fiber tensile toughness to a matrix tensile toughness as a function of the ratio of longitudinal normal stress to effective shear stress. The delamination between laminas is modeled by a strain-rate sensitive cohesive law. In the case of sandwich panels, core compaction is modeled by a crushable foam plasticity model with volumetric hardening and strain-rate sensitivity. These constitutive descriptions were used to predict deformation histories, fiber/matrix damage patterns, and inter-lamina delamination, for both monolithic and sandwich composite panels subjected to underwater blast. The numerical predictions were compared with experimental observations. We demonstrate that the new rate dependent composite damage model captures the spatial distribution and magnitude of damage significantly more accurately than previously developed models.

  14. An adaptive grid to improve the efficiency and accuracy of modelling underwater noise from shipping

    NASA Astrophysics Data System (ADS)

    Trigg, Leah; Chen, Feng; Shapiro, Georgy; Ingram, Simon; Embling, Clare

    2017-04-01

    Underwater noise from shipping is becoming a significant concern and has been listed as a pollutant under Descriptor 11 of the Marine Strategy Framework Directive. Underwater noise models are an essential tool to assess and predict noise levels for regulatory procedures such as environmental impact assessments and ship noise monitoring. There are generally two approaches to noise modelling. The first is based on simplified energy flux models, assuming either spherical or cylindrical propagation of sound energy. These models are very quick but they ignore important water column and seabed properties, and produce significant errors in the areas subject to temperature stratification (Shapiro et al., 2014). The second type of model (e.g. ray-tracing and parabolic equation) is based on an advanced physical representation of sound propagation. However, these acoustic propagation models are computationally expensive to execute. Shipping noise modelling requires spatial discretization in order to group noise sources together using a grid. A uniform grid size is often selected to achieve either the greatest efficiency (i.e. speed of computations) or the greatest accuracy. In contrast, this work aims to produce efficient and accurate noise level predictions by presenting an adaptive grid where cell size varies with distance from the receiver. The spatial range over which a certain cell size is suitable was determined by calculating the distance from the receiver at which propagation loss becomes uniform across a grid cell. The computational efficiency and accuracy of the resulting adaptive grid was tested by comparing it to uniform 1 km and 5 km grids. These represent an accurate and computationally efficient grid respectively. For a case study of the Celtic Sea, an application of the adaptive grid over an area of 160×160 km reduced the number of model executions required from 25600 for a 1 km grid to 5356 in December and to between 5056 and 13132 in August, which

  15. An analytical model for the underwater sound pressure waveforms radiated when an offshore pile is driven.

    PubMed

    Hall, Marshall V

    2015-08-01

    An analytical model has been developed for the pile vibration and consequent sound pressure and particle velocity radiated underwater when an offshore cylindrical pile is struck by a drop hammer. The model, which is based on the coupled equations of motion for axial and radial vibration of a thin cylindrical shell, yields frequency-dependent phase velocity and attenuation of these vibrations. The amplitude of the pulse of axial and radial displacement that travels down a pile following an axial impact is described in terms of the hammer properties. Solutions are obtained for the radiated sound pressure and particle velocity, using Junger and Feit's Transform Formulation of the Pressure Field of Cylindrical Radiators [(Acoustical Society of America, New York, 1993), p. 216]. The model is applied to published data on radiated noise from offshore driving of a steel pile. The modeled pressure waveforms at 12-m horizontal range and at 9 hydrophone depths correlate significantly with the measured waveforms. The modeled pressures of the initial positive peaks (appropriately low-pass filtered) agree with data to within 1 dB. The initial negative peaks however exceed the data by up to 7 dB, and as hydrophone depth increases, the model negative peaks have a maximum at 7 m, whereas the data have a maximum at 9 m.

  16. Dynamics of underwater legged locomotion: modeling and experiments on an octopus-inspired robot.

    PubMed

    Calisti, M; Corucci, F; Arienti, A; Laschi, C

    2015-07-30

    This paper studies underwater legged locomotion (ULL) by means of a robotic octopus-inspired prototype and its associated model. Two different types of propulsive actions are embedded into the robot model: reaction forces due to leg contact with the ground and hydrodynamic forces such as the drag arising from the sculling motion of the legs. Dynamic parameters of the model are estimated by means of evolutionary techniques and subsequently the model is exploited to highlight some distinctive features of ULL. Specifically, the separation between the center of buoyancy (CoB)/center of mass and density affect the stability and speed of the robot, whereas the sculling movements contribute to propelling the robot even when its legs are detached from the ground. The relevance of these effects is demonstrated through robotic experiments and model simulations; moreover, by slightly changing the position of the CoB in the presence of the same feed-forward activation, a number of different behaviors (i.e. forward and backward locomotion at different speeds) are achieved.

  17. Autonomous vehicles

    SciTech Connect

    Meyrowitz, A.L.; Blidberg, D.R.; Michelson, R.C. |

    1996-08-01

    There are various kinds of autonomous vehicles (AV`s) which can operate with varying levels of autonomy. This paper is concerned with underwater, ground, and aerial vehicles operating in a fully autonomous (nonteleoperated) mode. Further, this paper deals with AV`s as a special kind of device, rather than full-scale manned vehicles operating unmanned. The distinction is one in which the AV is likely to be designed for autonomous operation rather than being adapted for it as would be the case for manned vehicles. The authors provide a survey of the technological progress that has been made in AV`s, the current research issues and approaches that are continuing that progress, and the applications which motivate this work. It should be noted that issues of control are pervasive regardless of the kind of AV being considered, but that there are special considerations in the design and operation of AV`s depending on whether the focus is on vehicles underwater, on the ground, or in the air. The authors have separated the discussion into sections treating each of these categories.

  18. Synthetic Modeling of Autonomous Learning with a Chaotic Neural Network

    NASA Astrophysics Data System (ADS)

    Funabashi, Masatoshi

    We investigate the possible role of intermittent chaotic dynamics called chaotic itinerancy, in interaction with nonsupervised learnings that reinforce and weaken the neural connection depending on the dynamics itself. We first performed hierarchical stability analysis of the Chaotic Neural Network model (CNN) according to the structure of invariant subspaces. Irregular transition between two attractor ruins with positive maximum Lyapunov exponent was triggered by the blowout bifurcation of the attractor spaces, and was associated with riddled basins structure. We secondly modeled two autonomous learnings, Hebbian learning and spike-timing-dependent plasticity (STDP) rule, and simulated the effect on the chaotic itinerancy state of CNN. Hebbian learning increased the residence time on attractor ruins, and produced novel attractors in the minimum higher-dimensional subspace. It also augmented the neuronal synchrony and established the uniform modularity in chaotic itinerancy. STDP rule reduced the residence time on attractor ruins, and brought a wide range of periodicity in emerged attractors, possibly including strange attractors. Both learning rules selectively destroyed and preserved the specific invariant subspaces, depending on the neuron synchrony of the subspace where the orbits are situated. Computational rationale of the autonomous learning is discussed in connectionist perspective.

  19. Environmental modeling and recognition for an autonomous land vehicle

    NASA Technical Reports Server (NTRS)

    Lawton, D. T.; Levitt, T. S.; Mcconnell, C. C.; Nelson, P. C.

    1987-01-01

    An architecture for object modeling and recognition for an autonomous land vehicle is presented. Examples of objects of interest include terrain features, fields, roads, horizon features, trees, etc. The architecture is organized around a set of data bases for generic object models and perceptual structures, temporary memory for the instantiation of object and relational hypotheses, and a long term memory for storing stable hypotheses that are affixed to the terrain representation. Multiple inference processes operate over these databases. Researchers describe these particular components: the perceptual structure database, the grouping processes that operate over this, schemas, and the long term terrain database. A processing example that matches predictions from the long term terrain model to imagery, extracts significant perceptual structures for consideration as potential landmarks, and extracts a relational structure to update the long term terrain database is given.

  20. Active-imaging-based underwater navigation

    NASA Astrophysics Data System (ADS)

    Monnin, David; Schmitt, Gwenaël.; Fischer, Colin; Laurenzis, Martin; Christnacher, Frank

    2015-10-01

    Global navigation satellite systems (GNSS) are widely used for the localization and the navigation of unmanned and remotely operated vehicles (ROV). In contrast to ground or aerial vehicles, GNSS cannot be employed for autonomous underwater vehicles (AUV) without the use of a communication link to the water surface, since satellite signals cannot be received underwater. However, underwater autonomous navigation is still possible using self-localization methods which determines the relative location of an AUV with respect to a reference location using inertial measurement units (IMU), depth sensors and even sometimes radar or sonar imaging. As an alternative or a complementary solution to common underwater reckoning techniques, we present the first results of a feasibility study of an active-imaging-based localization method which uses a range-gated active-imaging system and can yield radiometric and odometric information even in turbid water.

  1. Statistical Modeling of Large-Scale Signal Path Loss in Underwater Acoustic Networks

    PubMed Central

    Llor, Jesús; Malumbres, Manuel Perez

    2013-01-01

    In an underwater acoustic channel, the propagation conditions are known to vary in time, causing the deviation of the received signal strength from the nominal value predicted by a deterministic propagation model. To facilitate a large-scale system design in such conditions (e.g., power allocation), we have developed a statistical propagation model in which the transmission loss is treated as a random variable. By applying repetitive computation to the acoustic field, using ray tracing for a set of varying environmental conditions (surface height, wave activity, small node displacements around nominal locations, etc.), an ensemble of transmission losses is compiled and later used to infer the statistical model parameters. A reasonable agreement is found with log-normal distribution, whose mean obeys a log-distance increases, and whose variance appears to be constant for a certain range of inter-node distances in a given deployment location. The statistical model is deemed useful for higher-level system planning, where simulation is needed to assess the performance of candidate network protocols under various resource allocation policies, i.e., to determine the transmit power and bandwidth allocation necessary to achieve a desired level of performance (connectivity, throughput, reliability, etc.). PMID:23396190

  2. Underwater Wireless Sensor Networks: How Do Acoustic Propagation Models Impact the Performance of Higher-Level Protocols?

    PubMed Central

    Llor, Jesús; Malumbres, Manuel P.

    2012-01-01

    Several Medium Access Control (MAC) and routing protocols have been developed in the last years for Underwater Wireless Sensor Networks (UWSNs). One of the main difficulties to compare and validate the performance of different proposals is the lack of a common standard to model the acoustic propagation in the underwater environment. In this paper we analyze the evolution of underwater acoustic prediction models from a simple approach to more detailed and accurate models. Then, different high layer network protocols are tested with different acoustic propagation models in order to determine the influence of environmental parameters on the obtained results. After several experiments, we can conclude that higher-level protocols are sensitive to both: (a) physical layer parameters related to the network scenario and (b) the acoustic propagation model. Conditions like ocean surface activity, scenario location, bathymetry or floor sediment composition, may change the signal propagation behavior. So, when designing network architectures for UWSNs, the role of the physical layer should be seriously taken into account in order to assert that the obtained simulation results will be close to the ones obtained in real network scenarios. PMID:22438712

  3. Advanced underwater lift device

    NASA Technical Reports Server (NTRS)

    Flanagan, David T.; Hopkins, Robert C.

    1993-01-01

    Flexible underwater lift devices ('lift bags') are used in underwater operations to provide buoyancy to submerged objects. Commercially available designs are heavy, bulky, and awkward to handle, and thus are limited in size and useful lifting capacity. An underwater lift device having less than 20 percent of the bulk and less than 10 percent of the weight of commercially available models was developed. The design features a dual membrane envelope, a nearly homogeneous envelope membrane stress distribution, and a minimum surface-to-volume ratio. A proof-of-concept model of 50 kg capacity was built and tested. Originally designed to provide buoyancy to mock-ups submerged in NASA's weightlessness simulators, the device may have application to water-landed spacecraft which must deploy flotation upon impact, and where launch weight and volume penalties are significant. The device may also be useful for the automated recovery of ocean floor probes or in marine salvage applications.

  4. Underwater lidar system: design challenges and application in pollution detection

    NASA Astrophysics Data System (ADS)

    Gupta, Pradip; Sankolli, Swati; Chakraborty, A.

    2016-05-01

    The present remote sensing techniques have imposed limitations in the applications of LIDAR Technology. The fundamental sampling inadequacy of the remote sensing data obtained from satellites is that they cannot resolve in the third spatial dimension, the vertical. This limits our possibilities of measuring any vertical variability in the water column. Also the interaction between the physical and biological process in the oceans and their effects at subsequent depths cannot be modeled with present techniques. The idea behind this paper is to introduce underwater LIDAR measurement system by using a LIDAR mounted on an Autonomous Underwater Vehicle (AUV). The paper introduces working principles and design parameters for the LIDAR mounted AUV (AUV-LIDAR). Among several applications the papers discusses the possible use and advantages of AUV-LIDAR in water pollution detection through profiling of Dissolved Organic Matter (DOM) in water bodies.

  5. A three-dimensional vibroacoustic model for the prediction of underwater noise from offshore pile driving

    NASA Astrophysics Data System (ADS)

    Tsouvalas, A.; Metrikine, A. V.

    2014-04-01

    Steel monopiles are nowadays widely used as foundations for a large number of offshore structures. The installation procedure commonly involves a pile driving process which can last up to several hours depending upon pile dimensions, soil conditions and input energy of the hydraulic hammer. In impact pile driving, a hydraulic hammer delivers a series of hammer blows at the head of the pile that drive the pile into the sediment. Each hammer strike results in pile vibrations that emit strong impulsive sounds into the water column which can be harmful for the marine ecosystem. With today's increasing concern regarding the environmental impact of such operations, engineering tools which will be able to provide reliable predictions of the underwater noise levels are required. In this study, a linear semi-analytical formulation of the coupled vibroacoustics of a complete pile-water-soil interaction model is addressed. The pile is described by a high order thin shell theory whereas both water and soil are modelled as three-dimensional continua. Results obtained with the developed model indicate that the near-field response in the water column consists mainly of pressure conical waves generated by the supersonic compressional waves in the pile excited by the impact hammer. The soil response is dominated by shear waves with almost vertical polarization. The Scholte waves are also generated at the water-seabed interface which can produce pressure fluctuations in the water column that are particularly significant close to the sea floor. The effects of soil elasticity and pile size are thoroughly investigated and their influence on the generated pressure levels is highlighted. The results are also compared with those ones of a similar model in which the soil is treated as an equivalent acoustic fluid. It is shown that the latter approximation can yield inaccurate results at low frequencies especially for harder soil sediments.

  6. Underwater Rays

    ERIC Educational Resources Information Center

    Cepic, Mojca

    2008-01-01

    Light beams in wavy unclear water, also called underwater rays, and caustic networks of light formed at the bottom of shallow water are two faces of a single phenomenon. Derivation of the caustic using only simple geometry, Snell's law and simple derivatives accounts for observations such as the existence of the caustic network on vertical walls,…

  7. Underwater Rays

    ERIC Educational Resources Information Center

    Cepic, Mojca

    2008-01-01

    Light beams in wavy unclear water, also called underwater rays, and caustic networks of light formed at the bottom of shallow water are two faces of a single phenomenon. Derivation of the caustic using only simple geometry, Snell's law and simple derivatives accounts for observations such as the existence of the caustic network on vertical walls,…

  8. Diabetic cardiac autonomic neuropathy: insights from animal models.

    PubMed

    Stables, Catherine L; Glasser, Rebecca L; Feldman, Eva L

    2013-10-01

    Cardiac autonomic neuropathy (CAN) is a relatively common and often devastating complication of diabetes. The major clinical signs are tachycardia, exercise intolerance, and orthostatic hypotension, but the most severe aspects of this complication are high rates of cardiac events and mortality. One of the earliest manifestations of CAN is reduced heart rate variability, and detection of this, along with abnormal results in postural blood pressure testing and/or the Valsalva maneuver, are central to diagnosis of the disease. The treatment options for CAN, beyond glycemic control, are extremely limited and lack evidence of efficacy. The underlying molecular mechanisms are also poorly understood. Thus, CAN is associated with a poor prognosis and there is a compelling need for research to understand, prevent, and reverse CAN. In this review of the literature we examine the use and usefulness of animal models of CAN in diabetes. Compared to other diabetic complications, the number of animal studies of CAN is very low. The published studies range across a variety of species, methods of inducing diabetes, and timescales examined, leading to high variability in study outcomes. The lack of well-characterized animal models makes it difficult to judge the relevance of these models to the human disease. One major advantage of animal studies is the ability to probe underlying molecular mechanisms, and the limited numbers of mechanistic studies conducted to date are outlined. Thus, while animal models of CAN in diabetes are crucial to better understanding and development of therapies, they are currently under-used.

  9. Aeroheating Mapping to Thermal Model for Autonomous Aerobraking Capability

    NASA Technical Reports Server (NTRS)

    Amundsen, Ruth M.

    2010-01-01

    Thermal modeling has been performed to evaluate the potential for autonomous aerobraking of a spacecraft in the atmosphere of a planet. As part of this modeling, the aeroheating flux during aerobraking must be applied to the spacecraft solar arrays to evaluate their thermal response. On the Mars Reconnaissance Orbiter (MRO) mission, this was done via two separate thermal models and an extensive suite of mapping scripts. That method has been revised, and the thermal analysis of an aerobraking pass can now be accomplished via a single thermal model, using a new capability in the Thermal Desktop software. This capability, Boundary Condition Mapper, has the ability to input heating flux files that vary with time, position on the solar array, and with the skin temperature. A recently added feature to the Boundary Condition Mapper is that this module can also utilize files that describe the variation of aeroheating over the surface with atmospheric density (rather than time); this is the format of the MRO aeroheating files. This capability has allowed a huge streamlining of the MRO thermal process, simplifying the procedure for importing new aeroheating files and trajectory information. The new process, as well as the quantified time savings, is described.

  10. Software control architecture for autonomous vehicles

    NASA Astrophysics Data System (ADS)

    Nelson, Michael L.; DeAnda, Juan R.; Fox, Richard K.; Meng, Xiannong

    1999-07-01

    The Strategic-Tactical-Execution Software Control Architecture (STESCA) is a tri-level approach to controlling autonomous vehicles. Using an object-oriented approach, STESCA has been developed as a generalization of the Rational Behavior Model (RBM). STESCA was initially implemented for the Phoenix Autonomous Underwater Vehicle (Naval Postgraduate School -- Monterey, CA), and is currently being implemented for the Pioneer AT land-based wheeled vehicle. The goals of STESCA are twofold. First is to create a generic framework to simplify the process of creating a software control architecture for autonomous vehicles of any type. Second is to allow for mission specification system by 'anyone' with minimal training to control the overall vehicle functionality. This paper describes the prototype implementation of STESCA for the Pioneer AT.

  11. Using Model-Based Reasoning for Autonomous Instrument Operation

    NASA Technical Reports Server (NTRS)

    Johnson, Mike; Rilee, M.; Truszkowski, W.; Powers, Edward I. (Technical Monitor)

    2000-01-01

    of environmental hazards, frame the problem of constructing autonomous science instruments. we are developing a model of the Low Energy Neutral Atom instrument (LENA) that is currently flying on board the Imager for Magnetosphere-to-Aurora Global Exploration (IMAGE) spacecraft. LENA is a particle detector that uses high voltage electrostatic optics and time-of-flight mass spectrometry to image neutral atom emissions from the denser regions of the Earth's magnetosphere. As with most spacecraft borne science instruments, phenomena in addition to neutral atoms are detected by LENA. Solar radiation and energetic particles from Earth's radiation belts are of particular concern because they may help generate currents that may compromise LENA's long term performance. An explicit model of the instrument response has been constructed and is currently in use on board IMAGE to dynamically adapt LENA to the presence or absence of energetic background radiations. The components of LENA are common in space science instrumentation, and lessons learned by modelling this system may be applied to other instruments. This work demonstrates that a model-based approach can be used to enhance science instrument effectiveness. Our future work involves the extension of these methods to cover more aspects of LENA operation and the generalization to other space science instrumentation.

  12. Using Model-Based Reasoning for Autonomous Instrument Operation

    NASA Technical Reports Server (NTRS)

    Johnson, Mike; Rilee, M.; Truszkowski, W.; Powers, Edward I. (Technical Monitor)

    2000-01-01

    of environmental hazards, frame the problem of constructing autonomous science instruments. we are developing a model of the Low Energy Neutral Atom instrument (LENA) that is currently flying on board the Imager for Magnetosphere-to-Aurora Global Exploration (IMAGE) spacecraft. LENA is a particle detector that uses high voltage electrostatic optics and time-of-flight mass spectrometry to image neutral atom emissions from the denser regions of the Earth's magnetosphere. As with most spacecraft borne science instruments, phenomena in addition to neutral atoms are detected by LENA. Solar radiation and energetic particles from Earth's radiation belts are of particular concern because they may help generate currents that may compromise LENA's long term performance. An explicit model of the instrument response has been constructed and is currently in use on board IMAGE to dynamically adapt LENA to the presence or absence of energetic background radiations. The components of LENA are common in space science instrumentation, and lessons learned by modelling this system may be applied to other instruments. This work demonstrates that a model-based approach can be used to enhance science instrument effectiveness. Our future work involves the extension of these methods to cover more aspects of LENA operation and the generalization to other space science instrumentation.

  13. On autonomous terrain model acquisition by a mobile robot

    SciTech Connect

    Rao, N.S.V.; Iyengar, S.S.; Weisbin, C.R.

    1987-01-20

    The following problem is considered: A point robot is placed in a terrain populated by unknown number of polyhedral obstacles of varied sizes and locations in two/three dimensions. The robot is equipped with a sensor capable of detecting all the obstacle vertices and edges that are visible from the present location of the robot. The robot is required to autonomously navigate and build the complete terrain model using the sensor information. It is established that the necessary number of scanning operations needed for complete terrain model acquisition by any algorithm that is based on 'scan from vertices' strategy is given by ..sigma../sub i = 1/sup n/N(O/sub i/) - n and ..sigma../sub i = 1/sup n/N(O/sub i/) - 2n in two and three dimensional terrains respectively, where O = )O/sub 1/,O/sub 2/,...,O/sub n/) set of the obstacles in the terrain, and N(O/sub i/) is the number of vertices of the obstacle O/sub i/.

  14. Onboard Atmospheric Modeling and Prediction for Autonomous Aerobraking Missions

    NASA Technical Reports Server (NTRS)

    Tolson, Robert H.; Prince, Jill L. H.

    2011-01-01

    Aerobraking has proven to be an effective means of increasing the science payload for planetary orbiting missions and/or for enabling the use of less expensive launch vehicles. Though aerobraking has numerous benefits, large operations cost have been required to maintain the aerobraking time line without violating aerodynamic heating or other constraints. Two operations functions have been performed on an orbit by orbit basis to estimate atmospheric properties relevant to aerobraking. The Navigation team typically solves for an atmospheric density scale factor using DSN tracking data and the atmospheric modeling team uses telemetric accelerometer data to recover atmospheric density profiles. After some effort, decisions are made about the need for orbit trim maneuvers to adjust periapsis altitude to stay within the aerobraking corridor. Autonomous aerobraking would reduce the need for many ground based tasks. To be successful, atmospheric modeling must be performed on the vehicle in near real time. This paper discusses the issues associated with estimating the planetary atmosphere onboard and evaluates a number of the options for Mars, Venus and Titan aerobraking missions.

  15. On autonomous terrain model acquistion by a mobile robot

    NASA Technical Reports Server (NTRS)

    Rao, N. S. V.; Iyengar, S. S.; Weisbin, C. R.

    1987-01-01

    The following problem is considered: A point robot is placed in a terrain populated by an unknown number of polyhedral obstacles of varied sizes and locations in two/three dimensions. The robot is equipped with a sensor capable of detecting all the obstacle vertices and edges that are visible from the present location of the robot. The robot is required to autonomously navigate and build the complete terrain model using the sensor information. It is established that the necessary number of scanning operations needed for complete terrain model acquisition by any algorithm that is based on scan from vertices strategy is given by the summation of i = 1 (sup n) N(O sub i)-n and summation of i = 1 (sup n) N(O sub i)-2n in two- and three-dimensional terrains respectively, where O = (O sub 1, O sub 2,....O sub n) set of the obstacles in the terrain, and N(O sub i) is the number of vertices of the obstacle O sub i.

  16. Algorithms and analysis for underwater vehicle plume tracing.

    SciTech Connect

    Byrne, Raymond Harry; Savage, Elizabeth L.; Hurtado, John Edward; Eskridge, Steven E.

    2003-07-01

    The goal of this research was to develop and demonstrate cooperative 3-D plume tracing algorithms for miniature autonomous underwater vehicles. Applications for this technology include Lost Asset and Survivor Location Systems (L-SALS) and Ship-in-Port Patrol and Protection (SP3). This research was a joint effort that included Nekton Research, LLC, Sandia National Laboratories, and Texas A&M University. Nekton Research developed the miniature autonomous underwater vehicles while Sandia and Texas A&M developed the 3-D plume tracing algorithms. This report describes the plume tracing algorithm and presents test results from successful underwater testing with pseudo-plume sources.

  17. Underwater Photogrammetry and Object Modeling: A Case Study of Xlendi Wreck in Malta

    PubMed Central

    Drap, Pierre; Merad, Djamal; Hijazi, Bilal; Gaoua, Lamia; Nawaf, Mohamad Motasem; Saccone, Mauro; Chemisky, Bertrand; Seinturier, Julien; Sourisseau, Jean-Christophe; Gambin, Timmy; Castro, Filipe

    2015-01-01

    In this paper we present a photogrammetry-based approach for deep-sea underwater surveys conducted from a submarine and guided by knowledge-representation combined with a logical approach (ontology). Two major issues are discussed in this paper. The first concerns deep-sea surveys using photogrammetry from a submarine. Here the goal was to obtain a set of images that completely covered the selected site. Subsequently and based on these images, a low-resolution 3D model is obtained in real-time, followed by a very high-resolution model produced back in the laboratory. The second issue involves the extraction of known artefacts present on the site. This aspect of the research is based on an a priori representation of the knowledge involved using systematic reasoning. Two parallel processes were developed to represent the photogrammetric process used for surveying as well as for identifying archaeological artefacts visible on the sea floor. Mapping involved the use of the CIDOC-CRM system (International Committee for Documentation (CIDOC)—Conceptual Reference Model)—This is a system that has been previously utilised to in the heritage sector and is largely available to the established scientific community. The proposed theoretical representation is based on procedural attachment; moreover, a strong link is maintained between the ontological description of the modelled concepts and the Java programming language which permitted 3D structure estimation and modelling based on a set of oriented images. A very recently discovered shipwreck acted as a testing ground for this project; the Xelendi Phoenician shipwreck, found off the Maltese coast, is probably the oldest known shipwreck in the western Mediterranean. The approach presented in this paper was developed in the scope of the GROPLAN project (Généralisation du Relevé, avec Ontologies et Photogrammétrie, pour l'Archéologie Navale et Sous-marine). Financed by the French National Research Agency (ANR) for four

  18. Underwater Photogrammetry and Object Modeling: A Case Study of Xlendi Wreck in Malta.

    PubMed

    Drap, Pierre; Merad, Djamal; Hijazi, Bilal; Gaoua, Lamia; Nawaf, Mohamad Motasem; Saccone, Mauro; Chemisky, Bertrand; Seinturier, Julien; Sourisseau, Jean-Christophe; Gambin, Timmy; Castro, Filipe

    2015-12-04

    In this paper we present a photogrammetry-based approach for deep-sea underwater surveys conducted from a submarine and guided by knowledge-representation combined with a logical approach (ontology). Two major issues are discussed in this paper. The first concerns deep-sea surveys using photogrammetry from a submarine. Here the goal was to obtain a set of images that completely covered the selected site. Subsequently and based on these images, a low-resolution 3D model is obtained in real-time, followed by a very high-resolution model produced back in the laboratory. The second issue involves the extraction of known artefacts present on the site. This aspect of the research is based on an a priori representation of the knowledge involved using systematic reasoning. Two parallel processes were developed to represent the photogrammetric process used for surveying as well as for identifying archaeological artefacts visible on the sea floor. Mapping involved the use of the CIDOC-CRM system (International Committee for Documentation (CIDOC)-Conceptual Reference Model)-This is a system that has been previously utilised to in the heritage sector and is largely available to the established scientific community. The proposed theoretical representation is based on procedural attachment; moreover, a strong link is maintained between the ontological description of the modelled concepts and the Java programming language which permitted 3D structure estimation and modelling based on a set of oriented images. A very recently discovered shipwreck acted as a testing ground for this project; the Xelendi Phoenician shipwreck, found off the Maltese coast, is probably the oldest known shipwreck in the western Mediterranean. The approach presented in this paper was developed in the scope of the GROPLAN project (Généralisation du Relevé, avec Ontologies et Photogrammétrie, pour l'Archéologie Navale et Sous-marine). Financed by the French National Research Agency (ANR) for four years

  19. Survivability design for a hybrid underwater vehicle

    SciTech Connect

    Wang, Biao; Wu, Chao; Li, Xiang; Zhao, Qingkai; Ge, Tong

    2015-03-10

    A novel hybrid underwater robotic vehicle (HROV) capable of working to the full ocean depth has been developed. The battery powered vehicle operates in two modes: operate as an untethered autonomous vehicle in autonomous underwater vehicle (AUV) mode and operate under remote control connected to the surface vessel by a lightweight, fiber optic tether in remotely operated vehicle (ROV) mode. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes, survivability has been placed on an equal level with the other design attributes of the HROV since the beginning of the project. This paper reports the survivability design elements for the HROV including basic vehicle design of integrated navigation and integrated communication, emergency recovery strategy, distributed architecture, redundant bus, dual battery package, emergency jettison system and self-repairing control system.

  20. DualTrust: A Distributed Trust Model for Swarm-Based Autonomic Computing Systems

    SciTech Connect

    Maiden, Wendy M.; Dionysiou, Ioanna; Frincke, Deborah A.; Fink, Glenn A.; Bakken, David E.

    2011-02-01

    For autonomic computing systems that utilize mobile agents and ant colony algorithms for their sensor layer, trust management is important for the acceptance of the mobile agent sensors and to protect the system from malicious behavior by insiders and entities that have penetrated network defenses. This paper examines the trust relationships, evidence, and decisions in a representative system and finds that by monitoring the trustworthiness of the autonomic managers rather than the swarming sensors, the trust management problem becomes much more scalable and still serves to protect the swarm. We then propose the DualTrust conceptual trust model. By addressing the autonomic manager’s bi-directional primary relationships in the ACS architecture, DualTrust is able to monitor the trustworthiness of the autonomic managers, protect the sensor swarm in a scalable manner, and provide global trust awareness for the orchestrating autonomic manager.

  1. Implementation of Deconfliction in Multivehicle Autonomous Systems

    DTIC Science & Technology

    2010-01-01

    two fin -actuated vehicles was replaced with a remote control toy shark controlled by a human operator. The human operator drove the toy shark directly...Fig. 4 Vehicle Swarm Technology Laboratory (VSTL) developed by the Boeing Research and Technology group. 3.2 University of Washington Fin -Actuated...Autonomous Underwater Vehicles The UW testbed is composed of a set of three fin -actuated autonomous underwater vehi- cles (Fig. 6) operating in a

  2. Autonomous Temperature Data Acquisition Compared to Existing Thermal Models of Different Sediments

    NASA Astrophysics Data System (ADS)

    Jackson, R. G.; Sanders, N. H.; Ward, C. C.; Ward, F. R.; Benson, S. M.; Lee, N. F.

    2010-03-01

    Our team wanted to improve sampling methods for experiments on the thermal properties of martian sediments. We built a robot that could take the data autonomously over a period of days, and then compared them to existing models.

  3. Sensing and modelling concepts for autonomous and remote mobile robot control

    NASA Astrophysics Data System (ADS)

    Yeung, S. K.; McMath, W. S.; Necsulescu, D.; Petriu, E. M.

    1993-01-01

    Sensing functions and modeling concepts for autonomous and remote mobile robot control in an unstructured environment are discussed. Sensing methods for robot position recovery, object recognition, and tactile teleoperator feedback are presented.

  4. Modeling and simulation of a counter-rotating turbine system for underwater vehicles

    NASA Astrophysics Data System (ADS)

    Wang, Xinping; Dang, Jianjun

    2016-12-01

    The structure of a counter-rotating turbine of an underwater vehicle is designed by adding the counter-rotating second-stage turbine disk after the conventional single-stage turbine. The available kinetic energy and the absorption power of the auxiliary system are calculated at different working conditions, and the results show that the power of the main engine and auxiliary system at the counter-rotating turbine system matches well with each other. The experimental simulation of the lubricating oil loop, fuel loop, and seawater loop are completed right before the technology scheme of the counter-rotating turbine system is proposed. The simulation results indicate that the hydraulic transmission system can satisfy the requirements for an underwater vehicle running at a steady sailing or variable working conditions.

  5. Underwater optical wireless communication network

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi

    2010-01-01

    The growing need for underwater observation and subsea monitoring systems has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. This communication technology is expected to play an important role in investigating climate change, in monitoring biological, biogeochemical, evolutionary, and ecological changes in the sea, ocean, and lake environments, and in helping to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), submarines, ships, buoys, and divers. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environments and facilities. Optical wireless communication has been proposed as the best alternative to meet this challenge. Models are presented for three kinds of optical wireless communication links: (a) a line-of-sight link, (b) a modulating retroreflector link, and (c) a reflective link, all of which can provide the required data rate. We analyze the link performance based on these models. From the analysis, it is clear that as the water absorption increases, the communication performance decreases dramatically for the three link types. However, by using the scattered light it was possible to mitigate this decrease in some cases. It is concluded from the analysis that a high-data-rate underwater optical wireless network is a feasible solution for emerging applications such as UUV-to-UUV links and networks of sensors, and extended ranges in these applications could be achieved by applying a multi-hop concept.

  6. Zebrafish model of tuberous sclerosis complex reveals cell-autonomous and non-cell-autonomous functions of mutant tuberin.

    PubMed

    Kim, Seok-Hyung; Speirs, Christina K; Solnica-Krezel, Lilianna; Ess, Kevin C

    2011-03-01

    Tuberous sclerosis complex (TSC) is an autosomal dominant disease caused by mutations in either the TSC1 (encodes hamartin) or TSC2 (encodes tuberin) genes. Patients with TSC have hamartomas in various organs throughout the whole body, most notably in the brain, skin, eye, heart, kidney and lung. To study the development of hamartomas, we generated a zebrafish model of TSC featuring a nonsense mutation (vu242) in the tsc2 gene. This tsc2(vu242) allele encodes a truncated Tuberin protein lacking the GAP domain, which is required for inhibition of Rheb and of the TOR kinase within TORC1. We show that tsc2(vu242) is a recessive larval-lethal mutation that causes increased cell size in the brain and liver. Greatly elevated TORC1 signaling is observed in tsc2(vu242/vu242) homozygous zebrafish, and is moderately increased in tsc2(vu242/+) heterozygotes. Forebrain neurons are poorly organized in tsc2(vu242/vu242) homozygous mutants, which have extensive gray and white matter disorganization and ectopically positioned cells. Genetic mosaic analyses demonstrate that tsc2 limits TORC1 signaling in a cell-autonomous manner. However, in chimeric animals, tsc2(vu242/vu242) mutant cells also mislocalize wild-type host cells in the forebrain in a non-cell-autonomous manner. These results demonstrate a highly conserved role of tsc2 in zebrafish and establish a new animal model for studies of TSC. The finding of a non-cell-autonomous function of mutant cells might help explain the formation of brain hamartomas and cortical malformations in human TSC.

  7. Acoustic generation of underwater cavities-Comparing modeled and measured acoustic signals generated by seismic air gun arrays.

    PubMed

    Khodabandeloo, Babak; Landrø, Martin; Hanssen, Alfred

    2017-04-01

    Underwater vapor cavities can be generated by acoustic stimulation. When the acoustic signals from several air guns are reflected from the sea surface, the pressure drop at some locations is sufficient for cavity growth and subsequent collapse. In this paper the generation of multiple water vapor cavities and their collapses are numerically modeled and the results are validated by comparing with field data from a seismic air gun array test. In a first modeling attempt where cavity interaction is neglected, a correspondence between measured and modeled data is found. Then, this correspondence is improved by assuming that the acoustic signal generated by the other cavities changes the hydrostatic pressure surrounding each cavity. This modeling can be used to estimate the amount and strength of high frequency signals generated by typical marine air gun arrays, given that a calibration step is performed prior to the modeling.

  8. Hierarchical Model Predictive Image-Based Visual Servoing of Underwater Vehicles With Adaptive Neural Network Dynamic Control.

    PubMed

    Gao, Jian; Proctor, Alison A; Shi, Yang; Bradley, Colin

    2016-10-01

    This paper proposes a hierarchical image-based visual servoing (IBVS) strategy for dynamic positioning of a fully actuated underwater vehicle. In the kinematic loop, the desired velocity is generated by a nonlinear model predictive controller, which optimizes a cost function of the predicted image trajectories under the constraints of visibility and velocity. A velocity reference model, representing the desired closed-loop vehicle dynamics, is integrated with an IBVS kinematic model to predict the future trajectories. In the dynamic velocity tracking loop, a neural-network-based model reference adaptive controller is designed to ensure the convergence of the velocity tracking error in the presence of uncertainties associated with vehicle dynamic parameters, water velocity, and thrust forces. Comparative simulations with different control and system configurations are performed to verify the effectiveness of the proposed scheme and to illustrate the influences of the prediction horizon, cost function, closed-loop vehicle dynamics, and predictive velocity reference model on the IBVS system performance.

  9. Mine Avoidance and Localization for Underwater Vehicles Using Continuous Curvature Path Generation and Non-Linear Tracking Control

    DTIC Science & Technology

    1993-09-01

    NAVAL POSTGRADUATE SCHOOL Monterey, California X A DTICSt FLCTT THESIS MINE AVOIDANCE AND LOCALIZATION FOR UNDERWATER VEHICLES USING CONTINUOUS...Claitficaion) MINE AVOIDANCE AND LOCALIZATION FOR UNDERWATER VEHICLES USING CONTINUOUS CURVATURE PATH GENERATION AND NON-LINEAR TRACKING CONTROL 12 PERSONAL...SUB-GROUP Mine avoidance and localization; Autonomous underwater vehicles (ALV); Autopilot and guidance of AUV II; Sliding mode control 19 ABSTRACT

  10. Modeling and Implementation of PID Control for Autonomous Robots

    DTIC Science & Technology

    2007-06-01

    Ground Vehicle. Monterey, California: Naval Postgraduate School, 2007. Jewett, John, and Raymound Serway . Physics for Scientists and Engineers ... with similar physical characteristics. These characteristics would include any two or four-wheeled robot with a motor controller for each side... FOR AUTONOMOUS ROBOTS Todd A. Williamson Ensign, United States Navy B.S. Chemical Engineering , University of Idaho, 2006 Submitted in

  11. Electrohydroelastic Euler-Bernoulli-Morison model for underwater resonant actuation of macro-fiber composite piezoelectric cantilevers

    NASA Astrophysics Data System (ADS)

    Shahab, S.; Erturk, A.

    2016-10-01

    Bio-inspired hydrodynamic thrust generation using smart materials has received growing attention over the past few years to enable improved maneuverability and agility, small form factor, reduced power consumption, and ease of fabrication in next-generation aquatic swimmers. In order to develop a high-fidelity model to predict the electrohydroelastic dynamics of macro-fiber composite (MFC) piezoelectric structures, in this work, mixing rules-based (i.e. rule of mixtures) electroelastic mechanics formulation is coupled with the global electroelastic dynamics based on the Euler-Bernoulli kinematics and nonlinear fluid loading based on Morison’s semi-empirical model. The focus is placed on the dynamic actuation problem for the first two bending vibration modes under geometrically and materially linear, hydrodynamically nonlinear behavior. The electroelastic and dielectric properties of a representative volume element (piezoelectric fiber and epoxy matrix) between two subsequent interdigitated electrodes are correlated to homogenized parameters of MFC bimorphs and validated for a set of MFCs that have the same overhang length but different widths. Following this process of electroelastic model development and validation, underwater actuation experiments are conducted for different length-to-width aspect ratios (L/b) in quiescent water, and the empirical drag and inertia coefficients are extracted from Morison’s equation to establish the electrohydroelastic model. The repeatability of these empirical coefficients is demonstrated for experiments conducted using aluminum cantilevers of different aspect ratios with a focus on the first two bending modes. The convergence of the nonlinear electrohydroelastic Euler-Bernoulli-Morison model to its hydrodynamically linear counterpart for increased L/b values is also reported. The proposed model, its harmonic balance analysis, and experimental results can be used not only for underwater piezoelectric actuation, but also for

  12. Underwater manipulator

    DOEpatents

    Schrum, P.B.; Cohen, G.H.

    1993-04-20

    Self-contained, waterproof, water-submersible, remote-controlled apparatus is described for manipulating a device, such as an ultrasonic transducer for measuring crack propagation on an underwater specimen undergoing shock testing. The subject manipulator includes metal bellows for transmittal of angular motions without the use of rotating shaft seals or O-rings. Inside the manipulator, a first stepper motor controls angular movement. In the preferred embodiment, the bellows permit the first stepper motor to move an ultrasonic transducer [plus minus]45 degrees in a first plane and a second bellows permit a second stepper motor to move the transducer [plus minus]10 degrees in a second plane orthogonal to the first. In addition, an XY motor-driven table provides XY motion.

  13. Underwater manipulator

    DOEpatents

    Schrum, Phillip B.; Cohen, George H.

    1993-01-01

    Self-contained, waterproof, water-submersible, remote-controlled apparatus is provided for manipulating a device, such as an ultrasonic transducer for measuring crack propagation on an underwater specimen undergoing shock testing. The subject manipulator includes metal bellows for transmittal of angular motions without the use of rotating shaft seals or O-rings. Inside the manipulator, a first stepper motor controls angular movement. In the preferred embodiment, the bellows permit the first stepper motor to move an ultrasonic transducer .+-.45 degrees in a first plane and a second bellows permit a second stepper motor to move the transducer .+-.10 degrees in a second plane orthogonal to the first. In addition, an XY motor-driven table provides XY motion.

  14. Underwater manipulator

    SciTech Connect

    Schrum, P.B.; Cohen, G.H.

    1992-12-31

    This invention is comprised of a self-contained, waterproof, water-submersible, remote-controlled apparatus provided for manipulating a device, such as an ultrasonic transducer for measuring crack propagation on an underwater specimen undergoing shock testing. The subject manipulator includes metal bellows for transmittal of angular motions without the use of rotating shaft seals or O-rings. Inside the manipulator, a first stepper motor controls angular movement. In the preferred embodiment, the bellows permit the first stepper motor to move an ultrasonic transducer {plus_minus} 45 degrees in a first plane and a second bellows permit a second stepper motor to move the transducer {plus_minus} 10 degrees in a second plane orthogonal to the first. In addition, an XY motor-driven table provides XY motion.

  15. Angiotensin-dependent autonomic dysregulation precedes dilated cardiomyopathy in a mouse model of muscular dystrophy.

    PubMed

    Sabharwal, Rasna; Weiss, Robert M; Zimmerman, Kathy; Domenig, Oliver; Cicha, Michael Z; Chapleau, Mark W

    2015-07-01

    What is the central question of this study? Is autonomic dysregulation in a mouse model of muscular dystrophy dependent on left ventricular systolic dysfunction and/or activation of the renin-angiotensin system (RAS) and does it predict development of dilated cardiomyopathy (DCM)? What is the main finding and its importance? The results demonstrate that autonomic dysregulation precedes and predicts left ventricular dysfunction and DCM in sarcoglycan-δ-deficient (Sgcd-/-) mice. The autonomic dysregulation is prevented by treatment of young Sgcd-/- mice with the angiotensin II type 1 receptor blocker losartan. Measurements of RAS activation and autonomic dysregulation may predict risk of DCM, and therapies targeting the RAS and autonomic dysregulation at a young age may slow disease progression in patients. Sarcoglycan mutations cause muscular dystrophy. Patients with muscular dystrophy develop autonomic dysregulation and dilated cardiomyopathy (DCM), but the temporal relationship and mechanism of autonomic dysregulation are not well understood. We hypothesized that activation of the renin-angiotensin system (RAS) causes autonomic dysregulation prior to development of DCM in sarcoglycan-δ-deficient (Sgcd-/-) mice and that the severity of autonomic dysfunction at a young age predicts the severity of DCM at older ages. At 10-12 weeks of age, when left ventricular function assessed by echocardiography remained normal, Sgcd-/- mice exhibited decreases in arterial pressure, locomotor activity, baroreflex sensitivity and cardiovagal tone and increased sympathetic tone compared with age-matched C57BL/6 control mice (P < 0.05). Systemic and skeletal muscle RAS were activated, and angiotensin II type 1 receptor (AT1 R) expression, superoxide and fibrosis were increased in dystrophic skeletal muscle (P < 0.05). Treatment with the AT1 R blocker losartan for 7-9 weeks beginning at 3 weeks of age prevented or strongly attenuated the abnormalities in Sgcd-/- mice (P < 0

  16. DualTrust: A Trust Management Model for Swarm-Based Autonomic Computing Systems

    SciTech Connect

    Maiden, Wendy M.

    2010-05-01

    Trust management techniques must be adapted to the unique needs of the application architectures and problem domains to which they are applied. For autonomic computing systems that utilize mobile agents and ant colony algorithms for their sensor layer, certain characteristics of the mobile agent ant swarm -- their lightweight, ephemeral nature and indirect communication -- make this adaptation especially challenging. This thesis looks at the trust issues and opportunities in swarm-based autonomic computing systems and finds that by monitoring the trustworthiness of the autonomic managers rather than the swarming sensors, the trust management problem becomes much more scalable and still serves to protect the swarm. After analyzing the applicability of trust management research as it has been applied to architectures with similar characteristics, this thesis specifies the required characteristics for trust management mechanisms used to monitor the trustworthiness of entities in a swarm-based autonomic computing system and describes a trust model that meets these requirements.

  17. SWARMs Ontology: A Common Information Model for the Cooperation of Underwater Robots

    PubMed Central

    Li, Xin; Bilbao, Sonia; Martín-Wanton, Tamara; Bastos, Joaquim; Rodriguez, Jonathan

    2017-01-01

    In order to facilitate cooperation between underwater robots, it is a must for robots to exchange information with unambiguous meaning. However, heterogeneity, existing in information pertaining to different robots, is a major obstruction. Therefore, this paper presents a networked ontology, named the Smart and Networking Underwater Robots in Cooperation Meshes (SWARMs) ontology, to address information heterogeneity and enable robots to have the same understanding of exchanged information. The SWARMs ontology uses a core ontology to interrelate a set of domain-specific ontologies, including the mission and planning, the robotic vehicle, the communication and networking, and the environment recognition and sensing ontology. In addition, the SWARMs ontology utilizes ontology constructs defined in the PR-OWL ontology to annotate context uncertainty based on the Multi-Entity Bayesian Network (MEBN) theory. Thus, the SWARMs ontology can provide both a formal specification for information that is necessarily exchanged between robots and a command and control entity, and also support for uncertainty reasoning. A scenario on chemical pollution monitoring is described and used to showcase how the SWARMs ontology can be instantiated, be extended, represent context uncertainty, and support uncertainty reasoning. PMID:28287468

  18. SWARMs Ontology: A Common Information Model for the Cooperation of Underwater Robots.

    PubMed

    Li, Xin; Bilbao, Sonia; Martín-Wanton, Tamara; Bastos, Joaquim; Rodriguez, Jonathan

    2017-03-11

    In order to facilitate cooperation between underwater robots, it is a must for robots to exchange information with unambiguous meaning. However, heterogeneity, existing in information pertaining to different robots, is a major obstruction. Therefore, this paper presents a networked ontology, named the Smart and Networking Underwater Robots in Cooperation Meshes (SWARMs) ontology, to address information heterogeneity and enable robots to have the same understanding of exchanged information. The SWARMs ontology uses a core ontology to interrelate a set of domain-specific ontologies, including the mission and planning, the robotic vehicle, the communication and networking, and the environment recognition and sensing ontology. In addition, the SWARMs ontology utilizes ontology constructs defined in the PR-OWL ontology to annotate context uncertainty based on the Multi-Entity Bayesian Network (MEBN) theory. Thus, the SWARMs ontology can provide both a formal specification for information that is necessarily exchanged between robots and a command and control entity, and also support for uncertainty reasoning. A scenario on chemical pollution monitoring is described and used to showcase how the SWARMs ontology can be instantiated, be extended, represent context uncertainty, and support uncertainty reasoning.

  19. Terrain modelling and motion planning for an autonomous exploration rover

    NASA Technical Reports Server (NTRS)

    Richard, F.; Benoliel, S.; Faugeras, O.; Grandjean, P.; Hayard, M.; Simeon, T.

    1994-01-01

    To assess the feasibility of planetary exploration missions using rovers, the French national agency CNES, with a consortium of European laboratories and industrial concerns, has initiated the Eureka project, 'Illustration of an Autonomous Robot for the Exploration of Space' (IARES). IARES is a demonstrator composed of a rover and a ground station, linked by telemetry and telecommand. It is aimed at verifying, on earth, robotic concepts developed by the RISP group of French laboratories (LAAS, INRIA, CERT, LETI) to perform scientific missions such as autonomous terrain sample collecting over large areas. To cope with the actual needs of planet exploration, IARES suitability is assessed through constraints on limited bandwidth, time delay and on-board resources. This autonomy relies heavily on robust onboard trajectory generation capabilities. This paper presents the main functions of the IARES navigation sub-system and shows how they are combined to allow movement in Mars-like environments. Section 2 gives an overall description of the IARES system. Section 3 details the functions of the Navigation sub-system, and finally, section 4 illustrates with a simple example the use of these functions.

  20. Modeling of systems wireless data transmission based on antenna arrays in underwater acoustic channels

    NASA Astrophysics Data System (ADS)

    Fedosov, V. P.; Lomakina, A. V.; Legin, A. A.; Voronin, V. V.

    2016-05-01

    In this paper the system of wireless transmission of data based on the use an adaptive algorithm for processing spatial-time signals using antenna arrays is presented. In the transmission of data in a multipath propagation of signals have been used such technologies as a MIMO (Multiple input-Multiple output) and OFDM (Orthogonal frequency division multiplexing) to solve the problem of increasing the maximum speed of data transfer and the low probability of errors. The adaptation process is based on the formation of the directional pattern equivalent to the amplitude antenna array in the signal arrival direction with the highest capacity on one of propagation paths in the channel. The simulation results showed that the use of an adaptive algorithm on the reception side can significantly reduce the probability of bit errors, thus to increase throughput in an underwater acoustic data channel.

  1. Autonomous motivation: involvement in physical activity, and perceived sport competence: structural and mediator models.

    PubMed

    Bagøien, Tor Egil; Halvari, Hallgeir

    2005-02-01

    Students in upper secondary school (N = 231, M = 16.6 yr., SD = 1.6) were tested on involvement in physical activity, perceived sport competence, using the Perceived Competence Scale of Harter, and motivational regulation on the Self-regulation Questionnaire of Ryan and Connell. Correlations were positive among involvement in physical activity, autonomous motivation, and perceived sport competence. A hypothetical model indicated that autonomous motivation mediates the relation between perceived sport competence and involvement in physical activity. Although LISREL analysis supported this mediation, the best model fit of the data supported a structural model with involvement in physical activity (R2 = .63) to mediate between autonomous motivation and perceived competence (R2 = .47). Results are interpreted and discussed in terms of self-determination theory.

  2. Experiments and simulation models of a basic computation element of an autonomous molecular computing system

    NASA Astrophysics Data System (ADS)

    Takinoue, Masahiro; Kiga, Daisuke; Shohda, Koh-Ichiroh; Suyama, Akira

    2008-10-01

    Autonomous DNA computers have been attracting much attention because of their ability to integrate into living cells. Autonomous DNA computers can process information through DNA molecules and their molecular reactions. We have already proposed an idea of an autonomous molecular computer with high computational ability, which is now named Reverse-transcription-and-TRanscription-based Autonomous Computing System (RTRACS). In this study, we first report an experimental demonstration of a basic computation element of RTRACS and a mathematical modeling method for RTRACS. We focus on an AND gate, which produces an output RNA molecule only when two input RNA molecules exist, because it is one of the most basic computation elements in RTRACS. Experimental results demonstrated that the basic computation element worked as designed. In addition, its behaviors were analyzed using a mathematical model describing the molecular reactions of the RTRACS computation elements. A comparison between experiments and simulations confirmed the validity of the mathematical modeling method. This study will accelerate construction of various kinds of computation elements and computational circuits of RTRACS, and thus advance the research on autonomous DNA computers.

  3. Experiments and simulation models of a basic computation element of an autonomous molecular computing system.

    PubMed

    Takinoue, Masahiro; Kiga, Daisuke; Shohda, Koh-Ichiroh; Suyama, Akira

    2008-10-01

    Autonomous DNA computers have been attracting much attention because of their ability to integrate into living cells. Autonomous DNA computers can process information through DNA molecules and their molecular reactions. We have already proposed an idea of an autonomous molecular computer with high computational ability, which is now named Reverse-transcription-and-TRanscription-based Autonomous Computing System (RTRACS). In this study, we first report an experimental demonstration of a basic computation element of RTRACS and a mathematical modeling method for RTRACS. We focus on an AND gate, which produces an output RNA molecule only when two input RNA molecules exist, because it is one of the most basic computation elements in RTRACS. Experimental results demonstrated that the basic computation element worked as designed. In addition, its behaviors were analyzed using a mathematical model describing the molecular reactions of the RTRACS computation elements. A comparison between experiments and simulations confirmed the validity of the mathematical modeling method. This study will accelerate construction of various kinds of computation elements and computational circuits of RTRACS, and thus advance the research on autonomous DNA computers.

  4. Underwater lab

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    The University of Southern California's Catalina Marine Science Center (CMSC) has announced plans to build an underwater marine research laboratory near Santa Catalina Island off the California coast. The project, which will take 2 years to build, will be sponsored by the National Oceanic and Atmospheric Administration (NOAA). The laboratory will be similar in concept to the U.S. Navy Sea Lab III, which was canceled some time ago.The project's purpose is to give divers access to a laboratory without having to surface. The project leader, Andrew Pilmanis, of the University of Southern California, stated recently (Industrial Research and Development, July 1983): “By the nature of the work, scientists require a lot of bottom time, and to do it by scuba isn't practical…. The only way to do that is with saturation diving. Once the diver is saturated with inert gas, whether the individual stays a few days or for months, only one decompression is required.” Divers will typically stay in the laboratory for 7-10 days. The laboratory will initially be placed at a depth of 20 m, later to be refloated and located at depths to 37 m.

  5. A collision model for safety evaluation of autonomous intelligent cruise control.

    PubMed

    Touran, A; Brackstone, M A; McDonald, M

    1999-09-01

    This paper describes a general framework for safety evaluation of autonomous intelligent cruise control in rear-end collisions. Using data and specifications from prototype devices, two collision models are developed. One model considers a train of four cars, one of which is equipped with autonomous intelligent cruise control. This model considers the car in front and two cars following the equipped car. In the second model, none of the cars is equipped with the device. Each model can predict the possibility of rear-end collision between cars under various conditions by calculating the remaining distance between cars after the front car brakes. Comparing the two collision models allows one to evaluate the effectiveness of autonomous intelligent cruise control in preventing collisions. The models are then subjected to Monte Carlo simulation to calculate the probability of collision. Based on crash probabilities, an expected value is calculated for the number of cars involved in any collision. It is found that given the model assumptions, while equipping a car with autonomous intelligent cruise control can significantly reduce the probability of the collision with the car ahead, it may adversely affect the situation for the following cars.

  6. Convergence of Asymptotic Systems of Non-autonomous Neural Network Models with Infinite Distributed Delays

    NASA Astrophysics Data System (ADS)

    Oliveira, José J.

    2017-02-01

    In this paper, we investigate the global convergence of solutions of non-autonomous Hopfield neural network models with discrete time-varying delays, infinite distributed delays, and possible unbounded coefficient functions. Instead of using Lyapunov functionals, we explore intrinsic features between the non-autonomous systems and their asymptotic systems to ensure the boundedness and global convergence of the solutions of the studied models. Our results are new and complement known results in the literature. The theoretical analysis is illustrated with some examples and numerical simulations.

  7. Impact of Measured vs. Predicted Residual Lung Volume on Body Fat Percentage Using Underwater Weighing and 4-Compartment Model.

    PubMed

    Nickerson, Brett S; Esco, Michael R; Bishop, Phillip A; Schumacker, Randall E; Richardson, Mark T; Fedewa, Michael V; Wingo, Jonathan E; Welborn, Bailey A

    2017-09-01

    Nickerson, BS, Esco, MR, Bishop, PA, Schumacker, RE, Richardson, MT, Fedewa, MV, Wingo, JE, and Welborn, BA. Impact of measured vs. predicted residual lung volume on body fat percentage using underwater weighing and 4-compartment model. J Strength Cond Res 31(9): 2519-2527, 2017-The purpose of this study was to compare underwater weighing (UWW) and 4-compartment (4C) model body fat percentage (BF%) for predicted vs. simultaneously measured residual lung volume (RLV). Forty-seven women and 33 men (age = 22 ± 5 years) had UWW and 4C model BF% determined using Boren et al. (RLVBOREN), Goldman and Becklake (RLVGB), and Miller et al. (RLVMILLER) RLV prediction equations. Criterion UWW BF% included body density (BD) values with simultaneous RLV. Criterion 4C model BF% included BD through UWW with simultaneous RLV, total body water through bioimpedance spectroscopy, and bone mineral content through dual-energy x-ray absorptiometry. The standard error of estimate (SEE) for UWW and 4C model BF% determined through RLV prediction equations varied from 2.0 to 2.6% and from 1.3 to 1.5%, respectively. The constant error (CE) was significantly different for UWW BF% when using RLVBOREN, RLVGB, and RLVMILLER (all p < 0.016; CE = 0.7, -2.0, 1.0%, respectively). However, the CEs for RLVBOREN and RLVMILLER were not significant in the 4C model (p = 0.73 and 0.11; CE = 0.1 and 0.2%, respectively), whereas RLVGB remained significantly different (p < 0.001; CE = -1.5%). The 95% limits of agreement were less than ±5.2% for UWW BF% and less than ±3.1% for the 4C model when using the 3 RLV equations. When used in a 4C model, the RLV equations yielded a smaller CE, SEE, and 95% limits of agreement than UWW BF% results. However, because of the range of individual error shown in the current study, caution should be employed when using the 4C model as a criterion method with predicted RLV.

  8. Enriching the hierarchical model of achievement motivation: autonomous and controlling reasons underlying achievement goals.

    PubMed

    Michou, Aikaterini; Vansteenkiste, Maarten; Mouratidis, Athanasios; Lens, Willy

    2014-12-01

    The hierarchical model of achievement motivation presumes that achievement goals channel the achievement motives of need for achievement and fear of failure towards motivational outcomes. Yet, less is known whether autonomous and controlling reasons underlying the pursuit of achievement goals can serve as additional pathways between achievement motives and outcomes. We tested whether mastery approach, performance approach, and performance avoidance goals and their underlying autonomous and controlling reasons would jointly explain the relation between achievement motives (i.e., fear of failure and need for achievement) and learning strategies (Study 1). Additionally, we examined whether the autonomous and controlling reasons underlying learners' dominant achievement goal would account for the link between achievement motives and the educational outcomes of learning strategies and cheating (Study 2). Six hundred and six Greek adolescent students (Mage = 15.05, SD = 1.43) and 435 university students (Mage M = 20.51, SD = 2.80) participated in studies 1 and 2, respectively. In both studies, a correlational design was used and the hypotheses were tested via path modelling. Autonomous and controlling reasons underlying the pursuit of achievement goals mediated, respectively, the relation of need for achievement and fear of failure to aspects of learning outcomes. Autonomous and controlling reasons underlying achievement goals could further explain learners' functioning in achievement settings. © 2014 The British Psychological Society.

  9. Autonomous Optimal Rendezvous of Underwater Vehicles

    DTIC Science & Technology

    2004-09-01

    the data gathering operation based on conditions sensed by the device ( Andrews , 2004). Improvement came with tethers which also contained...missions (Department of the Navy, 2000). An example of an economic application is the Hugins AUV, which has been used extensively and effectively for...necessary condition for the function E( rt ) to have a minimum is 2 2 2 ( ) ( ) ( ) ( )0 2 3 ( )( ) 2 ( ) 3 r r r r r r r r r r r r E t BR t R t dR tA t

  10. Autonomous Underwater Vehicle (AUV) Fest 2007 Summary

    DTIC Science & Technology

    2007-01-01

    The Technology Cooperation Panel (TTCP) conducted the Mongoose 07 Trial. The focus of the TTCP is to leverage research being conducted in the five...TTCP countries Australia, Canada, New Zealand, United Kingdom and the United States. The goals of the Mongoose 07 Trial were to demonstrate coalition

  11. Terminal Homing for Autonomous Underwater Vehicle Docking

    DTIC Science & Technology

    2016-06-01

    previously, an AUVs PUC increases after the initial vehicle fix. Unless the PUC is reduced through additional vehicle fixes, the vehicle will begin the... Physical /Functional Area Sea State 3 1 kWh internally‐rechargeable Lithium‐ion 20 hrs at 2 knots;9 hours at 4 knots Direct drive DC brushless motor... Physical /Functional Area Characteristic 18 Table 3. Kearfott SeaDeViL INS System Specifications. Source: [22]. Physical /Functional Area

  12. Tracking Control for Autonomous Underwater Vehicles

    DTIC Science & Technology

    2002-12-01

    Unclassified 20. LIMITATION OF ABSTRACT UL NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. 239-18 ii...could be developed and tuned to better handle this tracking control problem. This example will merely set a standard for which to compare later control...Change to disrcete [Ecd,Fcd]=c2d(Ec,Fc,dt); [Asd,Bsd]=c2d(As,Bs,dt); [ Asdm ,Bsdm]=c2d(Asm,Bsm,dt); % Aries response with error space

  13. Autonomous Underwater Vehicle Planning for Information Exploitation

    DTIC Science & Technology

    2012-03-01

    probabilistic analysis process. 173 %********************************************************************** 174 175 global OG SnrImg PrOpoly PrEpoly 176...and Calculate Information Gain 193 194 [IGC1]=OGupdate(SnrImg, PrOpoly ,PrEpoly); % IGC1: IG Calculation 195 IG=IGC1; 196 197 %% Stern Points used for...PrOmdlfunc and 10 % PrEmdlfunc. 11 12 % The pdf’s may be plotted by uncommenting the plotting code in the last 13 % cell. 14 15 global PrOpoly PrEpoly 16 17

  14. Mission Executor for an Autonomous Underwater Vehicle

    DTIC Science & Technology

    1991-09-01

    missions can be bound at least for the time being. Some preVious rseach has suggested that AUV behaviors might in fact be smndardized. The University...executor (emergency situation) but report of an obstacle at the limit of the sonar is a different matter. The obstacle is assigned a confidence ...factor which comes frmn the Sonar Processing Suite. Obstacles of high or medium 67 confidence cause the path to be replanned. The rationale is that the

  15. Development of a Broadband Underwater Sound Projector

    DTIC Science & Technology

    1997-01-01

    classification systems use existing transducer designs, such as the tonpilz (piston) transducers . This type of design has been selected to provide a maximum...source level at 20 kHz with high efficiency and reliability as well as excellent directivity responses. The manufacturing of the tonpilz transducer is...an autonomous underwater vehicle (AUV). The transducer is resonant at 100 kHz but has been designed to deliver high sound pressure levels without

  16. Biosensor for underwater chemical sensing (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Kusterbeck, Anne W.; Deschamps, Jeffrey R.; Charles, Paul T.

    2005-05-01

    Emerging biosensor approaches may prove useful in reducing false positives and improving detection probabilities for unexploded ordnance (UXO) and underwater explosives. NRL researchers previously developed a biosensor that was field-tested and validated for use in environmental remediation to detect explosives in groundwater. The sensor relies on the selective recognition by antibodies of target analytes, including the common explosives TNT and RDX. Laboratory work has demonstrated that sensors based on these displacement immunoassay formats can detect explosives at the part-per-trillion level in seawater. More recently, participating in an Office of Naval Research program on Chemical Sensing in the Marine Environment (CSME), tests were conducted in controlled underwater experiments at San Clemente, CA and Duck, NC. Simulated UXO targets, autonomous underwater vehicles (AUV) and multiple sensor approaches were used to demonstrate the feasibility of underwater chemical sensing. Efforts are now underway to integrate the biosensor into an underwater platform as part of a broader sensor system. We will describe results of these studies and outline possible operational scenarios for applications in harbor security.

  17. Chinese Students' Goal Orientation in English Learning: A Study Based on Autonomous Inquiry Model

    ERIC Educational Resources Information Center

    Zhang, Jianfeng

    2014-01-01

    Goal orientation is a kind of theory of learning motivation, which helps learners to develop their capability by emphasis on new techniques acquiring and environment adapting. In this study, based on the autonomous inquiry model, the construction of Chinese students' goal orientations in English learning are summarized according to the data…

  18. Enriching the Hierarchical Model of Achievement Motivation: Autonomous and Controlling Reasons Underlying Achievement Goals

    ERIC Educational Resources Information Center

    Michou, Aikaterini; Vansteenkiste, Maarten; Mouratidis, Athanasios; Lens, Willy

    2014-01-01

    Background: The hierarchical model of achievement motivation presumes that achievement goals channel the achievement motives of need for achievement and fear of failure towards motivational outcomes. Yet, less is known whether autonomous and controlling reasons underlying the pursuit of achievement goals can serve as additional pathways between…

  19. Enriching the Hierarchical Model of Achievement Motivation: Autonomous and Controlling Reasons Underlying Achievement Goals

    ERIC Educational Resources Information Center

    Michou, Aikaterini; Vansteenkiste, Maarten; Mouratidis, Athanasios; Lens, Willy

    2014-01-01

    Background: The hierarchical model of achievement motivation presumes that achievement goals channel the achievement motives of need for achievement and fear of failure towards motivational outcomes. Yet, less is known whether autonomous and controlling reasons underlying the pursuit of achievement goals can serve as additional pathways between…

  20. Underwater terrain positioning method based on least squares estimation for AUV

    NASA Astrophysics Data System (ADS)

    Chen, Peng-yun; Li, Ye; Su, Yu-min; Chen, Xiao-long; Jiang, Yan-qing

    2015-12-01

    To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwater terrainmatching data. An underwater terrain interpolation error compensation method based on fractional Brownian motion is proposed for defects of normal terrain interpolation, and an underwater terrain-matching positioning method based on least squares estimation (LSE) is proposed for correlation analysis of topographic features. The Fisher method is introduced as a secondary criterion for pseudo localization appearing in a topographic features flat area, effectively reducing the impact of pseudo positioning points on matching accuracy and improving the positioning accuracy of terrain flat areas. Simulation experiments based on electronic chart and multi-beam sea trial data show that drift errors of an inertial navigation system can be corrected effectively using the proposed method. The positioning accuracy and practicality are high, satisfying the requirement of underwater accurate positioning.

  1. A Study of Kinematics Modeling and the Computational Optimization of the Human Underwater Undulatory Kick by Comparison of Swimmers and Body Orientations

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoran; Liu, Geng; Ren, Yan; Dong, Haibo; Flow Simulation Research Group Team

    2014-11-01

    Underwater Undulatory Swimming (UUS), better known as the underwater dolphin kick, is the most important technique in competitive swimming. Faster than three of the four strokes in swimming, UUS is permitted in the 15 m after dives and turns. In this study, we compared the UUS of a college-level swimmer and a younger swimmer. 3D human models were built and reconstructed using stereo-videos for identifying key components of undulatory kick kinematics with respect to strongly flexing joints. A gradient-based optimizer and an immersed boundary method based CFD solver was then used to study the hydrodynamic performance of each swimmer. Optimal settings of current kinematic models will help us to understand the efficiency of the observed undulatory kick mechanisms and further improvements of the human UUS strategy. This work is supported by NSF CEBT-1313217 and UVa HooS-STER program.

  2. Sensory and autonomic function and structure in footpads of a diabetic mouse model

    PubMed Central

    Liu, Ying; Sebastian, Blessan; Liu, Ben; Zhang, Yiyue; Fissel, John A.; Pan, Baohan; Polydefkis, Michael; Farah, Mohamed H.

    2017-01-01

    Sensory and autonomic neuropathy affects the majority of type II diabetic patients. Clinically, autonomic evaluation often focuses on sudomotor function yet this is rarely assessed in animal models. We undertook morphological and functional studies to assess large myelinated and small unmyelinated axons in the db/db type II diabetes mouse model. We observed that autonomic innervation of sweat glands in the footpads was significantly reduced in db/db mice compared to control db/+ mice and this deficit was greater compared to reductions in intraepidermal sensory innervation of adjacent epidermis. Additionally, db/db mice formed significantly fewer sweat droplets compared to controls as early as 6 weeks of age, a time when no statistical differences were observed electrophysiologically between db/db and db/+ mice studies of large myelinated sensory and motor nerves. The rate of sweat droplet formation was significantly slower and the sweat droplet size larger and more variable in db/db mice compared to controls. Whereas pilocarpine and glycopyrrolate increased and decreased sweating, respectively, in 6 month-old controls, db/db mice did not respond to pharmacologic manipulations. Our findings indicate autonomic neuropathy is an early and prominent deficit in the db/db model and have implications for the development of therapies for peripheral diabetic neuropathy. PMID:28128284

  3. Real-Time Modeling of Cross-Body Flow for Torpedo Tube Recovery of the Phoenix Autonomous Underwater Vehicle (AUV)

    DTIC Science & Technology

    1998-03-01

    5. INVOCATION INSTRUCTIONS 201 LIST OF REFERENCES 203 INITIAL DISTRIBUTION LIST 207 -IX- LIST OF FIGURES Figure 1.1 The Phoenix AUV...205 206, 213, 207 215, 216, 210 211, 218, 212 213, 220, 214 217, 222, 223 218, 225, 219 221, 227, 222 229, 230, 224 225, 232, 226 228, 234...198, 205, 199, -1, , -1, 200, 207 , 201, -1, , -1, 209, 210, 204, -1, -1, 205, 212, 206, -1, -1, 207 , 214, 208, -1, -1, 210, 217, 211, -1

  4. High accuracy navigation information estimation for inertial system using the multi-model EKF fusing adams explicit formula applied to underwater gliders.

    PubMed

    Huang, Haoqian; Chen, Xiyuan; Zhang, Bo; Wang, Jian

    2017-01-01

    The underwater navigation system, mainly consisting of MEMS inertial sensors, is a key technology for the wide application of underwater gliders and plays an important role in achieving high accuracy navigation and positioning for a long time of period. However, the navigation errors will accumulate over time because of the inherent errors of inertial sensors, especially for MEMS grade IMU (Inertial Measurement Unit) generally used in gliders. The dead reckoning module is added to compensate the errors. In the complicated underwater environment, the performance of MEMS sensors is degraded sharply and the errors will become much larger. It is difficult to establish the accurate and fixed error model for the inertial sensor. Therefore, it is very hard to improve the accuracy of navigation information calculated by sensors. In order to solve the problem mentioned, the more suitable filter which integrates the multi-model method with an EKF approach can be designed according to different error models to give the optimal estimation for the state. The key parameters of error models can be used to determine the corresponding filter. The Adams explicit formula which has an advantage of high precision prediction is simultaneously fused into the above filter to achieve the much more improvement in attitudes estimation accuracy. The proposed algorithm has been proved through theory analyses and has been tested by both vehicle experiments and lake trials. Results show that the proposed method has better accuracy and effectiveness in terms of attitudes estimation compared with other methods mentioned in the paper for inertial navigation applied to underwater gliders.

  5. Underwater hearing: A review

    NASA Astrophysics Data System (ADS)

    Al-Masri, M.; Martin, A.; Nedwell, J.

    1993-05-01

    In view of the prevalence of hearing loss among commercial divers and the absence of widely accepted noise exposure limits for occupational underwater use, a review of studies of underwater hearing thresholds and hearing mechanisms was undertaken with the ultimate aim of developing noise exposure limits. Previous studies of underwater hearing thresholds appear to show that the ear underwater is less sensitive than compared with air. However, a surprisingly wide range of values for underwater hearing thresholds was reported, for example 35-90 dB SPL(re 20 MuPa) at 0.25 kHz and 30-80 dB at 1 kHz. No representative single threshold curve can be extracted with any validity. Possible reasons for such a wide scatter of results include high underwater ambient noise levels which may have masked the subjects underwater hearing thresholds, ill defined stimuli and underwater sound fields, and variable and informal audiometric methodology. Previous authors have proposed three somewhat interlinked theories to explain how sound is transmitted from water to the cochlea. These involve: the 'auricular' conduction pathway, the bone conduction pathway, and the dual conduction pathway. Up to this day, no one pathway has been shown to predominate, and all of them have been poorly evaluated. It is also possible that the presence of air bubbles in the ear canal and increased water depth may have significant effects on underwater hearing thresholds. These effects may be dependent on the underwater hearing mechanism. Again, the studies reviewed give conflicting results and no valid conclusion can be drawn. It is apparent that further experimental studies are required to establish underwater hearing thresholds and to provide an understanding of the mechanisms of hearing underwater. These should be based upon suitable facilities and methodologies for testing hearing thresholds underwater following modern and scientific audio metric practice.

  6. Autonomous & Adaptive Oceanographic Feature Tracking on Board Autonomous Underwater Vehicles

    DTIC Science & Technology

    2015-02-01

    gravitational acceleration, and ρ is the average water density. is is analogous to a simple harmonic oscillator described by the differential equation ...formula used here to calculate sound speed is the MacKenzie Sound Speed Equation (1981) [65]. e calculated average acousticline depth range was 3–28 m with...with relatively constant salinity over depth, the water temperature dominates the density calculation in the equation of state for seawater [67]. is

  7. The Trans-Contextual Model of Autonomous Motivation in Education: Conceptual and Empirical Issues and Meta-Analysis

    ERIC Educational Resources Information Center

    Hagger, Martin S.; Chatzisarantis, Nikos L. D.

    2016-01-01

    The trans-contextual model outlines the processes by which autonomous motivation toward activities in a physical education context predicts autonomous motivation toward physical activity outside of school, and beliefs about, intentions toward, and actual engagement in, out-of-school physical activity. In the present article, we clarify the…

  8. The Trans-Contextual Model of Autonomous Motivation in Education: Conceptual and Empirical Issues and Meta-Analysis

    ERIC Educational Resources Information Center

    Hagger, Martin S.; Chatzisarantis, Nikos L. D.

    2016-01-01

    The trans-contextual model outlines the processes by which autonomous motivation toward activities in a physical education context predicts autonomous motivation toward physical activity outside of school, and beliefs about, intentions toward, and actual engagement in, out-of-school physical activity. In the present article, we clarify the…

  9. Using Model-Based Reasoning for Autonomous Instrument Operation - Lessons Learned From IMAGE/LENA

    NASA Technical Reports Server (NTRS)

    Johnson, Michael A.; Rilee, Michael L.; Truszkowski, Walt; Bailin, Sidney C.

    2001-01-01

    Model-based reasoning has been applied as an autonomous control strategy on the Low Energy Neutral Atom (LENA) instrument currently flying on board the Imager for Magnetosphere-to-Aurora Global Exploration (IMAGE) spacecraft. Explicit models of instrument subsystem responses have been constructed and are used to dynamically adapt the instrument to the spacecraft's environment. These functions are cast as part of a Virtual Principal Investigator (VPI) that autonomously monitors and controls the instrument. In the VPI's current implementation, LENA's command uplink volume has been decreased significantly from its previous volume; typically, no uplinks are required for operations. This work demonstrates that a model-based approach can be used to enhance science instrument effectiveness. The components of LENA are common in space science instrumentation, and lessons learned by modeling this system may be applied to other instruments. Future work involves the extension of these methods to cover more aspects of LENA operation and the generalization to other space science instrumentation.

  10. Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model

    PubMed Central

    Halievski, Katherine; Kemp, Michael Q.; Breedlove, S. Marc; Miller, Kyle E.

    2016-01-01

    Abstract Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-cell-autonomous fashion in muscle. The non-cell-autonomous mechanism is suggested by data from a unique “myogenic” transgenic (TG) mouse model in which an AR transgene expressed exclusively in skeletal muscle fibers triggers an androgen-dependent SBMA phenotype, including defects in retrograde transport. However, motoneurons in this TG model retain the endogenous AR gene, leaving open the possibility that impairments in transport in this model also depend on ARs in the motoneurons themselves. To test whether non-cell-autonomous mechanisms alone can perturb retrograde transport, we generated male TG mice in which the endogenous AR allele has the testicular feminization mutation (Tfm) and, consequently, is nonfunctional. Males carrying the Tfm allele alone show no deficits in motor function or axonal transport, with or without testosterone treatment. However, when Tfm males carrying the myogenic transgene (Tfm/TG) are treated with testosterone, they develop impaired motor function and defects in retrograde transport, having fewer retrogradely labeled motoneurons and deficits in endosomal flux based on time-lapse video microscopy of living axons. These findings demonstrate that non-cell-autonomous disease mechanisms originating in muscle are sufficient to induce defects in retrograde transport in motoneurons. PMID:27517091

  11. Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model.

    PubMed

    Halievski, Katherine; Kemp, Michael Q; Breedlove, S Marc; Miller, Kyle E; Jordan, Cynthia L

    2016-01-01

    Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-cell-autonomous fashion in muscle. The non-cell-autonomous mechanism is suggested by data from a unique "myogenic" transgenic (TG) mouse model in which an AR transgene expressed exclusively in skeletal muscle fibers triggers an androgen-dependent SBMA phenotype, including defects in retrograde transport. However, motoneurons in this TG model retain the endogenous AR gene, leaving open the possibility that impairments in transport in this model also depend on ARs in the motoneurons themselves. To test whether non-cell-autonomous mechanisms alone can perturb retrograde transport, we generated male TG mice in which the endogenous AR allele has the testicular feminization mutation (Tfm) and, consequently, is nonfunctional. Males carrying the Tfm allele alone show no deficits in motor function or axonal transport, with or without testosterone treatment. However, when Tfm males carrying the myogenic transgene (Tfm/TG) are treated with testosterone, they develop impaired motor function and defects in retrograde transport, having fewer retrogradely labeled motoneurons and deficits in endosomal flux based on time-lapse video microscopy of living axons. These findings demonstrate that non-cell-autonomous disease mechanisms originating in muscle are sufficient to induce defects in retrograde transport in motoneurons.

  12. A bihemispheric autonomic model for traumatic stress effects on health and behavior.

    PubMed

    Lee, Sung W; Gerdes, Lee; Tegeler, Catherine L; Shaltout, Hossam A; Tegeler, Charles H

    2014-01-01

    A bihemispheric autonomic model (BHAM) may support advanced understanding of traumatic stress effects on physiology and behavior. The model builds on established data showing hemispheric lateralization in management of the autonomic nervous system, and proposes that traumatic stress can produce dominant asymmetry in activity of bilateral homologous brain regions responsible for autonomic management. Rightward and leftward dominant asymmetries are associated with sympathetic high arousal or parasympathetic freeze tendencies, respectively, and return to relative symmetry is associated with improved autonomic regulation. Autonomic auto-calibration for recovery (inverse of Jacksonian dissolution proposed by polyvagal theory) has implications for risk behaviors associated with traumatic life stress. Trauma-induced high arousal may be associated with risk for maladaptive behaviors to attenuate arousal (including abuse of alcohol or sedative-hypnotics). Trauma-induced freeze mode (including callous-unemotional trait) may be associated with low resting heart rate and risk for conduct disorders. The model may explain higher prevalence of leftward hemispheric abnormalities reported in studies of violence. Implications of the BHAM are illustrated through case examples of a military special operations officer with history of traumatic brain injury and post-traumatic stress disorder, and a university student with persisting post-concussion symptoms. Both undertook use of a noninvasive closed-loop neurotechnology - high-resolution, relational, resonance-based, electroencephalic mirroring - with ensuing decrease in hemispheric asymmetry, improvement in heart rate variability, and symptom reduction. Finally, the BHAM aligns with calls for researchers to use brain-behavioral constructs (research domain criteria or RDoC, proposed by the National Institutes of Mental Health) as building blocks for assessment and intervention in mental health science.

  13. A bihemispheric autonomic model for traumatic stress effects on health and behavior

    PubMed Central

    Lee, Sung W.; Gerdes, Lee; Tegeler, Catherine L.; Shaltout, Hossam A.; Tegeler, Charles H.

    2014-01-01

    A bihemispheric autonomic model (BHAM) may support advanced understanding of traumatic stress effects on physiology and behavior. The model builds on established data showing hemispheric lateralization in management of the autonomic nervous system, and proposes that traumatic stress can produce dominant asymmetry in activity of bilateral homologous brain regions responsible for autonomic management. Rightward and leftward dominant asymmetries are associated with sympathetic high arousal or parasympathetic freeze tendencies, respectively, and return to relative symmetry is associated with improved autonomic regulation. Autonomic auto-calibration for recovery (inverse of Jacksonian dissolution proposed by polyvagal theory) has implications for risk behaviors associated with traumatic life stress. Trauma-induced high arousal may be associated with risk for maladaptive behaviors to attenuate arousal (including abuse of alcohol or sedative-hypnotics). Trauma-induced freeze mode (including callous-unemotional trait) may be associated with low resting heart rate and risk for conduct disorders. The model may explain higher prevalence of leftward hemispheric abnormalities reported in studies of violence. Implications of the BHAM are illustrated through case examples of a military special operations officer with history of traumatic brain injury and post-traumatic stress disorder, and a university student with persisting post-concussion symptoms. Both undertook use of a noninvasive closed-loop neurotechnology – high-resolution, relational, resonance-based, electroencephalic mirroring – with ensuing decrease in hemispheric asymmetry, improvement in heart rate variability, and symptom reduction. Finally, the BHAM aligns with calls for researchers to use brain-behavioral constructs (research domain criteria or RDoC, proposed by the National Institutes of Mental Health) as building blocks for assessment and intervention in mental health science. PMID:25136325

  14. Global asymptotic behaviour of positive solutions to a non-autonomous Nicholson's blowflies model with delays.

    PubMed

    Van Hien, Le

    2014-01-01

    This paper addresses the global existence and global asymptotic behaviour of positive solutions to a non-autonomous Nicholson's blowflies model with delays. By using a novel approach, sufficient conditions are derived for the existence and global exponential convergence of positive solutions of the model without any restriction on uniform positiveness of the per capita dead rate. Numerical examples are provided to illustrate the effectiveness of the obtained results.

  15. Underwater radiated noise from modern commercial ships.

    PubMed

    McKenna, Megan F; Ross, Donald; Wiggins, Sean M; Hildebrand, John A

    2012-01-01

    Underwater radiated noise measurements for seven types of modern commercial ships during normal operating conditions are presented. Calibrated acoustic data (<1000 Hz) from an autonomous seafloor-mounted acoustic recorder were combined with ship passage information from the Automatic Identification System. This approach allowed for detailed measurements (i.e., source level, sound exposure level, and transmission range) on ships of opportunity. A key result was different acoustic levels and spectral shapes observed from different ship-types. A 54 kGT container ship had the highest broadband source level at 188 dB re 1 μPa@1m; a 26 kGT chemical tanker had the lowest at 177 dB re 1 μPa@1m. Bulk carriers had higher source levels near 100 Hz, while container ship and tanker noise was predominantly below 40 Hz. Simple models to predict source levels of modern merchant ships as a group from particular ship characteristics (e.g., length, gross tonnage, and speed) were not possible given individual ship-type differences. Furthermore, ship noise was observed to radiate asymmetrically. Stern aspect noise levels are 5 to 10 dB higher than bow aspect noise levels. Collectively, these results emphasize the importance of including modern ship-types in quantifying shipping noise for predictive models of global, regional, and local marine environments.

  16. Autonomous mathematical models: constructing theories of metabolic control.

    PubMed

    Donaghy, Josephine

    2013-01-01

    This paper considers how the relationship between mathematical models and theories in biology may change over time, on the basis of a historical analysis of the development of a mathematical model of metabolism, metabolic control analysis, and its relationship to theories of metabolic control. I argue that one can distinguish two ways of characterising the relationship between models and theories, depending on the stage of model and/or theory development that one is considering: partial independence and autonomy. Partial independence describes a model's relationship with existing theory, thus referring to relationships that have already been established between model and theory during model construction. By contrast, autonomy is a feature of relationships which may become established between model and theory in the future, and is expressed by a model's open ended role in constructing emerging theory. These characteristics have often been conflated by existing philosophical accounts, partly because they can only be identified and analysed when adopting a historical perspective on scientific research. Adopting a clear distinction between partial independence and autonomy improves philosophical insight into the changing relationship between models and theories.

  17. Advancements in Underwater Inspection

    DTIC Science & Technology

    1989-05-01

    Guard. For example, the Underwater Survey in Lieu of Dry Dock program, mobile offshore drilling unit (MODU) underwater hull inspection, tension leg...could be used to perform various types of underwater inspection on tension leg platform (TLP) tendons and templates. Understanding inspection...intervention (Ref. 6). This technique has application to the inspection of the mooring chains and terminations on floating facilities, and tension leg

  18. Holistic Modeling for Human-Autonomous System Interaction

    DTIC Science & Technology

    2015-01-01

    primary mission for all vehicles is surveillance with the ultimate goal of locating specific objects of interest in urban coastal and inland settings...complex systems. Discrete event simulation (DES) models and system dynamics (SD) models are two different approaches that can be used to address these...better suited for modeling continuous performance feedback that is temporally dependent and is affected by qualitative variables such as trust. 15

  19. Road network modeling in open source GIS to manage the navigation of autonomous robots

    NASA Astrophysics Data System (ADS)

    Mangiameli, Michele; Muscato, Giovanni; Mussumeci, Giuseppe

    2013-10-01

    The autonomous navigation of a robot can be accomplished through the assignment of a sequence of waypoints previously identified in the territory to be explored. In general, the starting point is a vector graph of the network consisting of possible paths. The vector graph can be directly available in the case of actual road networks, or it can be modeled, i.e. on the basis of cartographic supports or, even better, of a digital terrain model (DTM). In this paper we present software procedures developed in Grass-GIS, PostGIS and QGIS environments to identify, model, and visualize a road graph and to extract and normalize sequence of waypoints which can be transferred to a robot for its autonomous navigation.

  20. Updraft Model for Development of Autonomous Soaring Uninhabited Air Vehicles

    NASA Technical Reports Server (NTRS)

    Allen, Michael J.

    2006-01-01

    Large birds and glider pilots commonly use updrafts caused by convection in the lower atmosphere to extend flight duration, increase cross-country speed, improve range, or simply to conserve energy. Uninhabited air vehicles may also have the ability to exploit updrafts to improve performance. An updraft model was developed at NASA Dryden Flight Research Center (Edwards, California) to investigate the use of convective lift for uninhabited air vehicles in desert regions. Balloon and surface measurements obtained at the National Oceanic and Atmospheric Administration Surface Radiation station (Desert Rock, Nevada) enabled the model development. The data were used to create a statistical representation of the convective velocity scale, w*, and the convective mixing-layer thickness, zi. These parameters were then used to determine updraft size, vertical velocity profile, spacing, and maximum height. This paper gives a complete description of the updraft model and its derivation. Computer code for running the model is also given in conjunction with a check case for model verification.

  1. Underwater color image segmentation method via RGB channel fusion

    NASA Astrophysics Data System (ADS)

    Xuan, Li; Mingjun, Zhang

    2017-02-01

    Aiming at the problem of low segmentation accuracy and high computation time by applying existing segmentation methods for underwater color images, this paper has proposed an underwater color image segmentation method via RGB color channel fusion. Based on thresholding segmentation methods to conduct fast segmentation, the proposed method relies on dynamic estimation of the optimal weights for RGB channel fusion to obtain the grayscale image with high foreground-background contrast and reaches high segmentation accuracy. To verify the segmentation accuracy of the proposed method, the authors have conducted various underwater comparative experiments. The experimental results demonstrate that the proposed method is robust to illumination, and it is superior to existing methods in terms of both segmentation accuracy and computation time. Moreover, a segmentation technique is proposed for image sequences for real-time autonomous underwater vehicle operations.

  2. Systems, methods and apparatus for modeling, specifying and deploying policies in autonomous and autonomic systems using agent-oriented software engineering

    NASA Technical Reports Server (NTRS)

    Hinchey, Michael G. (Inventor); Penn, Joaquin (Inventor); Sterritt, Roy (Inventor)

    2011-01-01

    Systems, methods and apparatus are provided through which in some embodiments, an agent-oriented specification modeled with MaCMAS, is analyzed, flaws in the agent-oriented specification modeled with MaCMAS are corrected, and an implementation is derived from the corrected agent-oriented specification. Described herein are systems, method and apparatus that produce fully (mathematically) tractable development of agent-oriented specification(s) modeled with methodology fragment for analyzing complex multiagent systems (MaCMAS) and policies for autonomic systems from requirements through to code generation. The systems, method and apparatus described herein are illustrated through an example showing how user formulated policies can be translated into a formal mode which can then be converted to code. The requirements-based programming systems, method and apparatus described herein may provide faster, higher quality development and maintenance of autonomic systems based on user formulation of policies.

  3. Mathematical model of unmanned aerial vehicle used for endurance autonomous monitoring

    SciTech Connect

    Chelaru, Teodor-Viorel; Chelaru, Adrian

    2014-12-10

    The paper purpose is to present some aspects regarding the control system of unmanned aerial vehicle - UAV, used to local observations, surveillance and monitoring interest area. The calculus methodology allows a numerical simulation of UAV evolution in bad atmospheric conditions by using nonlinear model, as well as a linear one for obtaining guidance command. The UAV model which will be presented has six DOF (degrees of freedom), and autonomous control system. This theoretical development allows us to build stability matrix, command matrix and control matrix and finally to analyse the stability of autonomous UAV flight. A robust guidance system, based on uncoupled state will be evaluated for different fly conditions and the results will be presented. The flight parameters and guidance will be analysed.

  4. Modeling for Semi-Autonomous Control of Cooperative Vehicles

    DTIC Science & Technology

    2009-01-15

    Environments," ASME International Mechanical Engineering Congress and Exposition, Nov2005. [17] M. Campbell, J. W. Lee, E. Scholte , D. Rathbun...pp. 1597-1609. [18] E. Scholte , M. Campbell, "Robust Nonlinear Model Predictive Control with Partial State Information," IEEE Transactions on

  5. Asymptotic behavior of a stochastic non-autonomous predator-prey model with impulsive perturbations

    NASA Astrophysics Data System (ADS)

    Wu, Ruihua; Zou, Xiaoling; Wang, Ke

    2015-03-01

    This paper is concerned with a stochastic non-autonomous Lotka-Volterra predator-prey model with impulsive effects. The asymptotic properties are examined. Sufficient conditions for persistence and extinction are obtained, our results demonstrate that the impulse has important effects on the persistence and extinction of the species. We also show that the solution is stochastically ultimate bounded under some conditions. Finally, several simulation figures are introduced to confirm our main results.

  6. A human body model with active muscles for simulation of pretensioned restraints in autonomous braking interventions.

    PubMed

    Osth, Jonas; Brolin, Karin; Bråse, Dan

    2015-01-01

    The aim of this work is to study driver and passenger kinematics in autonomous braking scenarios, with and without pretensioned seat belts, using a whole-body finite element (FE) human body model (HBM) with active muscles. Upper extremity musculature for elbow and shoulder flexion-extension feedback control was added to an HBM that was previously complemented with feedback controlled muscles for the trunk and neck. Controller gains were found using a radial basis function metamodel sampled by making 144 simulations of an 8 ms(-2) volunteer sled test. The HBM kinematics, interaction forces, and muscle activations were validated using a second volunteer data set for the passenger and driver positions, with and without 170 N seat belt pretension, in 11 ms(-2) autonomous braking deceleration. The HBM was then used for a parameter study in which seat belt pretension force and timing were varied from 170 to 570 N and from 0.25 s before to 0.15 s after deceleration onset, in an 11 ms(-2) autonomous braking scenario. The model validation showed that the forward displacements and interaction forces of the HBM correlated with those of corresponding volunteer tests. Muscle activations and head rotation angles were overestimated in the HBM when compared with volunteer data. With a standard seat belt in 11 ms(-2) autonomous braking interventions, the HBM exhibited peak forward head displacements of 153 and 232 mm for the driver and passenger positions. When 570 N seat belt pretension was applied 0.15 s before deceleration onset, a reduction of peak head displacements to 60 and 75 mm was predicted. Driver and passenger responses to autonomous braking with standard and pretensioned restraints were successfully modeled in a whole-body FE HBM with feedback controlled active muscles. Variations of belt pretension force level and timing revealed that belt pretension 0.15 s before deceleration onset had the largest effect in reducing forward head and torso movement caused

  7. Physics Based Model for Online Fault Detection in Autonomous Cryogenic Loading System

    NASA Technical Reports Server (NTRS)

    Kashani, Ali; Devine, Ekaterina Viktorovna P; Luchinsky, Dmitry Georgievich; Smelyanskiy, Vadim; Sass, Jared P.; Brown, Barbara L.; Patterson-Hine, Ann

    2013-01-01

    We report the progress in the development of the chilldown model for rapid cryogenic loading system developed at KSC. The nontrivial characteristic feature of the analyzed chilldown regime is its active control by dump valves. The two-phase flow model of the chilldown is approximated as one-dimensional homogeneous fluid flow with no slip condition for the interphase velocity. The model is built using commercial SINDAFLUINT software. The results of numerical predictions are in good agreement with the experimental time traces. The obtained results pave the way to the application of the SINDAFLUINT model as a verification tool for the design and algorithm development required for autonomous loading operation.

  8. A Queueing Model for Supervisory Control of Unmanned Autonomous Vehicles

    DTIC Science & Technology

    2013-09-01

    that analyze dynamic systems of flow have been developed in the domain of queueing theory . At SSC Pacific, we have applied queueing theory to teams...In this type of complex command and control (C2 scenario, UV operators will be subjected to vast amounts of information. Therefore, this theory ...Figure 8 shows the general model for a network of queues involving these servers. In an “open” queuing system, “customers” (tasks) arrive at each of

  9. Learning Preference Models for Autonomous Mobile Robots in Complex Domains

    DTIC Science & Technology

    2010-12-01

    utilize a terrain assessment approach named GESTALT [120, 121, 122], derived from an earlier approach named MORPHIN [123, 124, 125]. These ap...constructed to provide good empirical performance. For instance, the MORPHIN [123, 124, 125] and GESTALT [120, 121, 122] systems simply assume direct...the manual construction of preference models still result in a parameter tuning problem. For example, the MORPHIN [123, 124, 125] and GESTALT [120, 121

  10. Constitutive Model Calibration via Autonomous Multiaxial Experimentation (Postprint)

    DTIC Science & Technology

    2016-09-17

    replace experimental tests to avoid the costs associated with elaborate test fixtures and equipment or expensive physical specimens. In addition...certain stress states commonly of interest are difficult, if not impossible, to physically reproduce in experiments. Accurate material models that are...force and torque capabilities of 100 kN and 1100 N m, respectively. The test frame was controlled using a custom program written in MTS TestSuite. Axial

  11. Autonomous Coordination and Online Motion Modeling for Mobile Robots

    DTIC Science & Technology

    2007-09-01

    number of robots. The second goal of this work is to demonstrate a method by which a robot can automatically determine how it is moving...The second goal of this work is to demonstrate a method by which a robot can automatically determine how it is moving. Experiments demonstrate the...to introduce a method for automatically learning a robot’s motion model. The algorithm will be employed on real mobile robots so as to ensure the

  12. Coherence resonances in an autonomous thermochemical model with internal fluctuations

    NASA Astrophysics Data System (ADS)

    Lemarchand, A.; Nowakowski, B.

    2005-08-01

    Direct simulations of the master equation associated with a two-variable homogeneous thermochemical model are performed in order to analyze the effects of internal fluctuations on excitability and periodic oscillations. In both regimes, coherence resonances are observed in the absence of external noise and external forcing. These results suggest that the control of the combustion of lean premixed gas requires a stochastic description at a mesoscopic level.

  13. Colorful Underwater Sea Creatures

    ERIC Educational Resources Information Center

    McCutcheon, Heather

    2011-01-01

    In this article, the author describes a project wherein students created colorful underwater sea creatures. This project began with a discussion about underwater sea creatures and how they live. The first step was making the multi-colored tissue paper that would become sea creatures and seaweed. Once students had the shapes of their sea creatures…

  14. Colorful Underwater Sea Creatures

    ERIC Educational Resources Information Center

    McCutcheon, Heather

    2011-01-01

    In this article, the author describes a project wherein students created colorful underwater sea creatures. This project began with a discussion about underwater sea creatures and how they live. The first step was making the multi-colored tissue paper that would become sea creatures and seaweed. Once students had the shapes of their sea creatures…

  15. Underwater Scene Composition

    ERIC Educational Resources Information Center

    Kim, Nanyoung

    2009-01-01

    In this article, the author describes an underwater scene composition for elementary-education majors. This project deals with watercolor with crayon or oil-pastel resist (medium); the beauty of nature represented by fish in the underwater scene (theme); texture and pattern (design elements); drawing simple forms (drawing skill); and composition…

  16. Underwater Scene Composition

    ERIC Educational Resources Information Center

    Kim, Nanyoung

    2009-01-01

    In this article, the author describes an underwater scene composition for elementary-education majors. This project deals with watercolor with crayon or oil-pastel resist (medium); the beauty of nature represented by fish in the underwater scene (theme); texture and pattern (design elements); drawing simple forms (drawing skill); and composition…

  17. Underwater Flow Noise

    NASA Astrophysics Data System (ADS)

    Dowling, A. P.

    Lighthill's theory of aerodynamic sound provides an effective way of investigating underwater flow noise. When combined with a model of the coherent vortical structures in a turbulent boundary layer, it predicts the wave-number frequency pressure spectrum on a rigid surface and, in particular, highlights the rôle of surface viscous stresses as a source of low wave-number pressure fluctuations on a plane surface. The inclusion of surface curvature and flexibility enables the theory to be applied to acoustic streamers (sometimes known as towed arrays). The effect of the interior mechanical structure of the streamers on the flow noise is investigated. Simple algebraic forms are derived for the comparative performance of liquid and visco-elastic-filled streamers. The introduction of porous foam into a liquid streamer is found to be a particularly effective way of attenuating low wave-number disturbances, and theoretical predictions are compared with experiment.

  18. 3-D world modeling for an autonomous robot

    SciTech Connect

    Goldstein, M.; Pin, F.G.; Weisbin, C.R.

    1987-08-01

    This paper presents a methodology for a concise representation of the 3-D world model for a mobile robot, using range data. The process starts with the segmentation of the scene into ''objects'' that are given a unique label, based on principles of range continuity. Then the external surface of each object is partitioned into homogeneous surface patches. Contours of surface patches in 3-D space are identified by estimating the normal and curvature associated with each pixel. The resulting surface patches are then classified as planar, convex or concave. Since the world model uses a volumetric representation for the 3-D environment, planar surfaces are represented by thin volumetric polyhedra. Spherical and cylindrical surfaces are extracted and represented by appropriate volumetric primitives. All other surfaces are represented using the boolean union of spherical volumes (as described in a separate paper by the same authors). The result is a general, concise representation of the external 3-D world, which allows for efficient and robust 3-D object recognition. 20 refs., 14 figs.

  19. Time series modeling of autonomous hybrid power systems

    SciTech Connect

    Quinlan, P.J.; Beckman, W.A.; Mitchell, J.W.; Klein, S.A.; Blair, N.J.

    1997-12-31

    The Solar Energy Laboratory (SEL) has developed a wind diesel PV hybrid systems simulator, UW-HYBRID 1.0, as an application of the TRNSYS 14.2 time-series simulation environment. The simulator provides a customizable user interface. The simulation provides an AC/DC buss, diesel generators, wind turbines, PV modules, a battery bank, and power converter. PV system simulations include solar angle and peak power tracking options. Diesel simulations include estimated fuel-use and waste heat output, and are dispatched using a least-cost of fuel strategy. Wind system simulations include varying air density, wind shear and wake effects. Time step duration is user-selectable. This paper provides a description of the simulation models and example output.

  20. Model-based Executive Control through Reactive Planning for Autonomous Rovers

    NASA Technical Reports Server (NTRS)

    Finzi, Alberto; Ingrand, Felix; Muscettola, Nicola

    2004-01-01

    This paper reports on the design and implementation of a real-time executive for a mobile rover that uses a model-based, declarative approach. The control system is based on the Intelligent Distributed Execution Architecture (IDEA), an approach to planning and execution that provides a unified representational and computational framework for an autonomous agent. The basic hypothesis of IDEA is that a large control system can be structured as a collection of interacting agents, each with the same fundamental structure. We show that planning and real-time response are compatible if the executive minimizes the size of the planning problem. We detail the implementation of this approach on an exploration rover (Gromit an RWI ATRV Junior at NASA Ames) presenting different IDEA controllers of the same domain and comparing them with more classical approaches. We demonstrate that the approach is scalable to complex coordination of functional modules needed for autonomous navigation and exploration.

  1. Autonomous technology - sources of confusion: a model for explanation and prediction of conceptual shifts.

    PubMed

    Stensson, Patrik; Jansson, Anders

    2014-01-01

    Today, autonomous is often used for technology with a more intelligent self-management capability than common automation. This concept usage is maladaptive, ignoring both the distinction between autonomy and heteronomy according to Kant's categorical imperative and that the meaning of autonomy implies qualities technology cannot have. Being autonomous is about having the right to be wrong, a right justified by accountability and insightful understanding of real-life values, and it is about being externally uncontrollable. The contemporary use of autonomy as well as similar concepts is discussed and a model is presented showing how six sources of confusion interact in a vicious circle that impede human authority and autonomy. Our goal is to sort out these confusions and contribute to a development in which the different roles of machines and people, and human responsibilities, are explicated rather than blurred, which should facilitate the forming of truly beneficial and complementary systems.

  2. Toward Self-Referential Autonomous Learning of Object and Situation Models.

    PubMed

    Damerow, Florian; Knoblauch, Andreas; Körner, Ursula; Eggert, Julian; Körner, Edgar

    Most current approaches to scene understanding lack the capability to adapt object and situation models to behavioral needs not anticipated by the human system designer. Here, we give a detailed description of a system architecture for self-referential autonomous learning which enables the refinement of object and situation models during operation in order to optimize behavior. This includes structural learning of hierarchical models for situations and behaviors that is triggered by a mismatch between expected and actual action outcome. Besides proposing architectural concepts, we also describe a first implementation of our system within a simulated traffic scenario to demonstrate the feasibility of our approach.

  3. Autonomic, locomotor and cardiac abnormalities in a mouse model of muscular dystrophy: targeting the renin-angiotensin system.

    PubMed

    Sabharwal, Rasna; Chapleau, Mark W

    2014-04-01

    New Findings What is the topic of this review? This symposium report summarizes autonomic, cardiac and skeletal muscle abnormalities in sarcoglycan-δ-deficient mice (Sgcd-/-), a mouse model of limb girdle muscular dystrophy, with emphasis on the roles of autonomic dysregulation and activation of the renin-angiotensin system at a young age. What advances does it highlight? The contributions of the autonomic nervous system and the renin-angiotensin system to the pathogenesis of muscular dystrophy are highlighted. Results demonstrate that autonomic dysregulation precedes and predicts later development of cardiac dysfunction in Sgcd-/- mice and that treatment of young Sgcd-/- mice with the angiotensin type 1 receptor antagonist losartan or with angiotensin-(1-7) abrogates the autonomic dysregulation, attenuates skeletal muscle pathology and increases spontaneous locomotor activity. Muscular dystrophies are a heterogeneous group of genetic muscle diseases characterized by muscle weakness and atrophy. Mutations in sarcoglycans and other subunits of the dystrophin-glycoprotein complex cause muscular dystrophy and dilated cardiomyopathy in animals and humans. Aberrant autonomic signalling is recognized in a variety of neuromuscular disorders. We hypothesized that activation of the renin-angiotensin system contributes to skeletal muscle and autonomic dysfunction in mice deficient in the sarcoglycan-δ (Sgcd) gene at a young age and that this early autonomic dysfunction contributes to the later development of left ventricular (LV) dysfunction and increased mortality. We demonstrated that young Sgcd-/- mice exhibit histopathological features of skeletal muscle dystrophy, decreased locomotor activity and severe autonomic dysregulation, but normal LV function. Autonomic regulation continued to deteriorate in Sgcd-/- mice with age and was accompanied by LV dysfunction and dilated cardiomyopathy at older ages. Autonomic dysregulation at a young age predicted later development of

  4. What cycles the cell? -Robust autonomous cell cycle models.

    PubMed

    Lavi, Orit; Louzoun, Yoram

    2009-12-01

    The cell cycle is one of the best studied cellular mechanisms at the experimental and theoretical levels. Although most of the important biochemical components and reactions of the cell cycle are probably known, the precise way the cell cycle dynamics are driven is still under debate. This phenomenon is not atypical to many other biological systems where the knowledge of the molecular building blocks and the interactions between them does not lead to a coherent picture of the appropriate dynamics. We here propose a methodology to develop plausible models for the driving mechanisms of embryonic and cancerous cell cycles. We first define a key property of the system (a cyclic behaviour in the case of the embryonic cell cycle) and set mathematical constraints on the types of two variable simplified systems robustly reproducing such a cyclic behaviour. We then expand these robust systems to three variables and reiterate the procedure. At each step, we further limit the type of expanded systems to fit the known microbiology until a detailed description of the system is obtained. This methodology produces mathematical descriptions of the required biological systems that are more robust to changes in the precise function and rate constants. This methodology can be extended to practically any type of subcellular mechanism.

  5. Informal Workshop on Burial and Mobility Modeling of Munitions in the Underwater Environment

    DTIC Science & Technology

    2014-12-01

    sediments, large cobbles, and coral reefs . Heterogeneous bottom types (or mixtures) are also prevalent, complicating mobility modeling, as well as detection...managers, the concept may not apply to all sites of interest (e.g., coral reefs and rocky coasts). There was little confidence that any model would...WORKSHOP ON BURIAL AND MOBILITY MODELING 6 2.3. Past Projects MR-201003: Vortex Lattice UXO Mobility Model for Reef -Type Range Environments

  6. INVESTIGATION OF THE BASIC DESIGN PRINCIPLES OF THE FLEXTENSIONAL UNDERWATER ACOUSTIC TRANSDUCER.

    DTIC Science & Technology

    UNDERWATER SOUND EQUIPMENT, * TRANSDUCERS , MATHEMATICAL MODELS, UNDERWATER SOUND, SOUND TRANSMISSION, COMPUTER PROGRAMS, PERFORMANCE(ENGINEERING...ELECTRICAL IMPEDANCE, ELECTROMECHANICAL CONVERTERS, PIEZOELECTRIC TRANSDUCERS , SHELLS(STRUCTURAL FORMS), VIBRATION, EQUATIONS OF MOTION.

  7. Underwater Glider Dynamics and Control

    DTIC Science & Technology

    2002-09-30

    colleagues for underactuated systems (see, for example, Bloch, Leonard and Marsden [2001]). The method of controlled Lagrangians is a control...suited to underactuated systems , i.e., systems like underwater gliders that have fewer control inputs than system degrees of freedom. We will also... underactuated and constrained systems . In earlier work we have developed coordinated control strategies for fully actuated point mass vehicle models

  8. Ocean Research Enabled by Underwater Gliders.

    PubMed

    Rudnick, Daniel L

    2016-01-01

    Underwater gliders are autonomous underwater vehicles that profile vertically by changing their buoyancy and use wings to move horizontally. Gliders are useful for sustained observation at relatively fine horizontal scales, especially to connect the coastal and open ocean. In this review, research topics are grouped by time and length scales. Large-scale topics addressed include the eastern and western boundary currents and the regional effects of climate variability. The accessibility of horizontal length scales of order 1 km allows investigation of mesoscale and submesoscale features such as fronts and eddies. Because the submesoscales dominate vertical fluxes in the ocean, gliders have found application in studies of biogeochemical processes. At the finest scales, gliders have been used to measure internal waves and turbulent dissipation. The review summarizes gliders' achievements to date and assesses their future in ocean observation.

  9. Ocean Research Enabled by Underwater Gliders

    NASA Astrophysics Data System (ADS)

    Rudnick, Daniel L.

    2016-01-01

    Underwater gliders are autonomous underwater vehicles that profile vertically by changing their buoyancy and use wings to move horizontally. Gliders are useful for sustained observation at relatively fine horizontal scales, especially to connect the coastal and open ocean. In this review, research topics are grouped by time and length scales. Large-scale topics addressed include the eastern and western boundary currents and the regional effects of climate variability. The accessibility of horizontal length scales of order 1 km allows investigation of mesoscale and submesoscale features such as fronts and eddies. Because the submesoscales dominate vertical fluxes in the ocean, gliders have found application in studies of biogeochemical processes. At the finest scales, gliders have been used to measure internal waves and turbulent dissipation. The review summarizes gliders' achievements to date and assesses their future in ocean observation.

  10. Autonomous and Autonomic Swarms

    NASA Technical Reports Server (NTRS)

    Hinchey, Michael G.; Rash, James L.; Truszkowski, Walter F.; Rouff, Christopher A.; Sterritt, Roy

    2005-01-01

    A watershed in systems engineering is represented by the advent of swarm-based systems that accomplish missions through cooperative action by a (large) group of autonomous individuals each having simple capabilities and no global knowledge of the group s objective. Such systems, with individuals capable of surviving in hostile environments, pose unprecedented challenges to system developers. Design and testing and verification at much higher levels will be required, together with the corresponding tools, to bring such systems to fruition. Concepts for possible future NASA space exploration missions include autonomous, autonomic swarms. Engineering swarm-based missions begins with understanding autonomy and autonomicity and how to design, test, and verify systems that have those properties and, simultaneously, the capability to accomplish prescribed mission goals. Formal methods-based technologies, both projected and in development, are described in terms of their potential utility to swarm-based system developers.

  11. Three-dimensional numerical modeling of composite panels subjected to underwater blast

    NASA Astrophysics Data System (ADS)

    Wei, Xiaoding; Tran, Phuong; de Vaucorbeil, Alban; Ramaswamy, Ravi Bellur; Latourte, Felix; Espinosa, Horacio D.

    2013-06-01

    Designing lightweight high-performance materials that can sustain high impulsive loadings is of great interest for marine applications. In this study, a finite element fluid-structure interaction model was developed to understand the deformation and failure mechanisms of both monolithic and sandwich composite panels. Fiber (E-glass fiber) and matrix (vinylester resin) damage and degradation in individual unidirectional composite laminas were modeled using Hashin failure model. The delamination between laminas was modeled by a strain-rate sensitive cohesive law. In sandwich panels, core compaction (H250 PVC foam) is modeled by a crushable foam plasticity model with volumetric hardening and strain-rate sensitivity. The model-predicted deformation histories, fiber/matrix damage patterns, and inter-lamina delamination, in both monolithic and sandwich composite panels, were compared with experimental observations. The simulations demonstrated that the delamination process is strongly rate dependent, and that Hashin model captures the spatial distribution and magnitude of damage to a first-order approximation. The model also revealed that the foam plays an important role in improving panel performance by mitigating the transmitted impulse to the back-side face sheet while maintaining overall bending stiffness.

  12. Modeling the Autonomic and Metabolic Effects of Obstructive Sleep Apnea: A Simulation Study

    PubMed Central

    Cheng, Limei; Khoo, Michael C. K.

    2012-01-01

    Long-term exposure to intermittent hypoxia and sleep fragmentation introduced by recurring obstructive sleep apnea (OSA) has been linked to subsequent cardiovascular disease and Type 2 diabetes. The underlying mechanisms remain unclear, but impairment of the normal interactions among the systems that regulate autonomic and metabolic function is likely involved. We have extended an existing integrative model of respiratory, cardiovascular, and sleep–wake state control, to incorporate a sub-model of glucose–insulin–fatty acid regulation. This computational model is capable of simulating the complex dynamics of cardiorespiratory control, chemoreflex and state-related control of breath-to-breath ventilation, state-related and chemoreflex control of upper airway potency, respiratory and circulatory mechanics, as well as the metabolic control of glucose–insulin dynamics and its interactions with the autonomic control. The interactions between autonomic and metabolic control include the circadian regulation of epinephrine secretion, epinephrine regulation on dynamic fluctuations in glucose and free-fatty acid in plasma, metabolic coupling among tissues and organs provided by insulin and epinephrine, as well as the effect of insulin on peripheral vascular sympathetic activity. These model simulations provide insight into the relative importance of the various mechanisms that determine the acute and chronic physiological effects of sleep-disordered breathing. The model can also be used to investigate the effects of a variety of interventions, such as different glucose clamps, the intravenous glucose tolerance test, and the application of continuous positive airway pressure on OSA subjects. As such, this model provides the foundation on which future efforts to simulate disease progression and the long-term effects of pharmacological intervention can be based. PMID:22291654

  13. Noninvasive in vivo model demonstrating the effects of autonomic innervation on pancreatic islet function

    PubMed Central

    Rodriguez-Diaz, Rayner; Speier, Stephan; Molano, Ruth Damaris; Formoso, Alexander; Gans, Itai; Abdulreda, Midhat H.; Cabrera, Over; Molina, Judith; Fachado, Alberto; Ricordi, Camillo; Leibiger, Ingo; Pileggi, Antonello; Berggren, Per-Olof; Caicedo, Alejandro

    2012-01-01

    The autonomic nervous system is thought to modulate blood glucose homeostasis by regulating endocrine cell activity in the pancreatic islets of Langerhans. The role of islet innervation, however, has remained elusive because the direct effects of autonomic nervous input on islet cell physiology cannot be studied in the pancreas. Here, we used an in vivo model to study the role of islet nervous input in glucose homeostasis. We transplanted islets into the anterior chamber of the eye and found that islet grafts became densely innervated by the rich parasympathetic and sympathetic nervous supply of the iris. Parasympathetic innervation was imaged intravitally by using transgenic mice expressing GFP in cholinergic axons. To manipulate selectively the islet nervous input, we increased the ambient illumination to increase the parasympathetic input to the islet grafts via the pupillary light reflex. This reduced fasting glycemia and improved glucose tolerance. These effects could be blocked by topical application of the muscarinic antagonist atropine to the eye, indicating that local cholinergic innervation had a direct effect on islet function in vivo. By using this approach, we found that parasympathetic innervation influences islet function in C57BL/6 mice but not in 129X1 mice, which reflected differences in innervation densities and may explain major strain differences in glucose homeostasis. This study directly demonstrates that autonomic axons innervating the islet modulate glucose homeostasis. PMID:23236142

  14. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    PubMed Central

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  15. Calibration Techniques for Accurate Measurements by Underwater Camera Systems.

    PubMed

    Shortis, Mark

    2015-12-07

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems.

  16. AUV Positioning Method Based on Tightly Coupled SINS/LBL for Underwater Acoustic Multipath Propagation.

    PubMed

    Zhang, Tao; Shi, Hongfei; Chen, Liping; Li, Yao; Tong, Jinwu

    2016-03-11

    This paper researches an AUV (Autonomous Underwater Vehicle) positioning method based on SINS (Strapdown Inertial Navigation System)/LBL (Long Base Line) tightly coupled algorithm. This algorithm mainly includes SINS-assisted searching method of optimum slant-range of underwater acoustic propagation multipath, SINS/LBL tightly coupled model and multi-sensor information fusion algorithm. Fuzzy correlation peak problem of underwater LBL acoustic propagation multipath could be solved based on SINS positional information, thus improving LBL positional accuracy. Moreover, introduction of SINS-centered LBL locating information could compensate accumulative AUV position error effectively and regularly. Compared to loosely coupled algorithm, this tightly coupled algorithm can still provide accurate location information when there are fewer than four available hydrophones (or within the signal receiving range). Therefore, effective positional calibration area of tightly coupled system based on LBL array is wider and has higher reliability and fault tolerance than loosely coupled. It is more applicable to AUV positioning based on SINS/LBL.

  17. Determining spherical lens correction for astronaut training underwater

    PubMed Central

    Porter, Jason; Gibson, C. Robert; Strauss, Samuel

    2013-01-01

    Purpose To develop a model that will accurately predict the distance spherical lens correction needed to be worn by National Aeronautics and Space Administration (NASA) astronauts while training underwater. The replica space suit’s helmet contains curved visors that induce refractive power when submersed in water. Methods Anterior surface powers and thicknesses were measured for the helmet’s protective and inside visors. The impact of each visor on the helmet’s refractive power in water was analyzed using thick lens calculations and Zemax optical design software. Using geometrical optics approximations, a model was developed to determine the optimal distance spherical power needed to be worn underwater based on the helmet’s total induced spherical power underwater and the astronaut’s manifest spectacle plane correction in air. The validity of the model was tested using data from both eyes of 10 astronauts who trained underwater. Results The helmet visors induced a total power of −2.737 D when placed underwater. The required underwater spherical correction (FW) was linearly related to the spectacle plane spherical correction in air (FAir): FW = FAir + 2.356 D. The mean magnitude of the difference between the actual correction worn underwater and the calculated underwater correction was 0.20 ± 0.11 D. The actual and calculated values were highly correlated (R = 0.971) with 70% of eyes having a difference in magnitude of < 0.25 D between values. Conclusions We devised a model to calculate the spherical spectacle lens correction needed to be worn underwater by National Aeronautics and Space Administration astronauts. The model accurately predicts the actual values worn underwater and can be applied (more generally) to determine a suitable spectacle lens correction to be worn behind other types of masks when submerged underwater. PMID:21623249

  18. Efficient Modelling of Small Bodies Gravitational Potential for Autonomous Proximity Operations

    NASA Astrophysics Data System (ADS)

    Turconi, Andrea; Palmer, Phil; Roberts, Mark

    Maintaining missions in proximity of small bodies requires extensive orbit determination and ground station time due to a ground-in-the-loop approach. Recent developments in on-board navigation paved the way for autonomous proximity operations. The missing elements for achieving this goal are a gravity model, simple enough to be easily used by the spacecraft to steer itself around the asteroid, and guidance laws that rely on a such an inherently simple model. In this research we identified a class of models that can represent well some characteristics of the dynamical environment around small bodies. In particular we chose to fit the positions and Jacobi energies of the equilibrium points generated by the balance of gravity and centrifugal acceleration in the body fixed frame. In this way these gravity models give also a good estimate of the condition of stability against impact for orbital trajectories. Making use of these approximate models we show autonomous guidance laws for achieving body fixed hovering in proximity of the asteroid while ensuring that no impact with the small body will occur during the approach.

  19. Analysis of a 2D simulation model of biofilms with autonomous cells

    NASA Astrophysics Data System (ADS)

    Bhandar, Anand; Tatek, Yergou; Slater, Gary

    2006-03-01

    Biofilms are substances consisting of a large number of microorganisms that grow on surfaces in contact with liquids. They can be found growing in water pipes, on surgical instruments or on tooth surfaces. Mathematical models have been used for the last three decades in order to improve our understanding of their growth and behavior. We have designed and implemented a new Monte Carlo model based on the life of autonomous cells and investigated the static and dynamic characteristics of the resulting bacterial populations. Each cell is modeled as an autonomous agent whose behavior is controlled by thermodynamic parameters, mechanical properties, physiological rules and environmental conditions. In the 2D version studied, a cell is represented by a closed chain of self-avoiding beads linked together using the bond fluctuation algorithm. The cell is controlled both by the rigidity of its membrane and a pressure difference. The model is complemented by key features such as the processes of cell division, growth and death, attractive interactions between the cell and the surface, and the explicit presence of nutrient diffusion. Tuning model parameters leads to the growth and maturation of various types of biofilms. Typical colonies incorporating these and other important characteristics of biofilms such as the exopolymeric substance (EPS), metabolism and waste production, cell motility and chemotaxy, and cell mutation will be presented.

  20. Underwater Multi-Node Radio Communication Solutions for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Kawar, Zaid Fares Yousef; Haddad, Sanad Atef Sari; Mestariheh, Feras R. M.; Jonsson, Lars Jonas

    2015-01-01

    The exploration of the presumably life harboring subsurface ocean of Europa will provide scientists with extensive new knowledge in the search for extraterrestrial life. A highly miniaturized payload is required to penetrate a narrow passage through the thick ice crust covering Europa's surface. Underwater wireless communications may be the most viable means of communication for such exploratory missions, accounting for size and weight restrictions. This presents a challenge to achieve satisfactory data rates and a range that permits autonomous underwater vehicles (AUVs) to communicate within their region of operation, as well as with a surface lander or orbiter. This work presents thorough prototype experimentation on an underwater communication system established between several nodes using RF signals. During an eight-week internship experience at NASA's Ames Research Center in September-October 2014, our team developed a Europa exploration mission concept, built representative hardware, and carried out tests to assess the feasibility of key aspects of the concept. Experiments demonstrating the viability of RF communication underwater comprised inspecting the effect of depth and horizontal distance on signal strength as well as the optimum positioning of antennas. To test the system's performance, two submersibles were designed and built. A commercially available remotely operated vehicle (ROV) was also modified and used as a main communication node. The two submersibles were wirelessly connected and accommodated sensors capable of characterizing water properties and equipped with 2.4 GHz, 1 mW transceivers to communicate the measured data. The communication procedure is that the main communication node requests the collected data from the two submersibles when in range and receives it instantly through RF. This work models what may take place during an actual mission to Europa. The developed mission concept involved a hybrid communication system consisting of

  1. Fluid-Interaction and Cavitation Effects on a Surface Ship Model Due to an Underwater Explosion.

    DTIC Science & Technology

    1996-09-01

    itself is conducting the solution process which would normally be a SOL 109 transient analysis process in MSC/ NASTRAN . Appendix B provides the DMAP ... NASTRAN [Ref. 6], the engineer has a greater ability to improve ship modeling and predict the vibrational response of ship hulls and internal equipment...specifically associated by the MAT field in the NASTRAN ASCII input file. Because of the numerical processing in the USA code, node numbering needs to be

  2. Model-Based Assessment of Cardiovascular Autonomic Control in Children with Obstructive Sleep Apnea

    PubMed Central

    Chaicharn, Jarree; Lin, Zheng; Chen, Maida L.; Ward, Sally L.D.; Keens, Thomas; Khoo, Michael C. K.

    2009-01-01

    Study Objectives: To quantitatively assess daytime autonomic cardiovascular control in pediatric subjects with and without obstructive sleep apnea syndrome (OSAS). Design: Respiration, R-R intervals, and noninvasive continuous blood pressure were monitored in awake subjects in the supine and standing postures, as well as during cold face stimulation. Setting: Sleep disorders laboratory in a hospital setting. Participants: Ten pediatric patients (age 11.4 ± 3.6 years) with moderate to severe OSAS (obstructive apnea-hypopnea index = 21.0 ± 6.6/ h) before treatment and 10 age-matched normal control subjects (age 11.5 ± 3.7 years). Measurements and Results: Spectral analysis of heart rate variability revealed that high-frequency power was similar and the ratio of low- to high-frequency power was lower in subjects with OSAS vs control subjects. The closed-loop minimal model allowed heart rate variability to be partitioned into a component mediated by respiratory-cardiac coupling and a baroreflex component, whereas blood pressure variability was assumed to result from the direct effects of respiration and fluctuations in cardiac output. Baroreflex gain was lower in subjects with OSAS vs control subjects. Under orthostatic stress, respiratory-cardiac coupling gain decreased in both subject groups, but baroreflex gain decreased only in controls. The model was extended to incorporate time-varying parameter changes for analysis of the data collected during cold face stimulation: cardiac output gain increased in controls but remained unchanged in OSAS. Conclusions: Our findings suggest that vagal modulation of the heart remains relatively normal in pediatric subjects with OSAS. However, baseline cardiovascular sympathetic activity is elevated, and reactivity to autonomic challenges is impaired. Citation: Chaicharn J; Lin Z; Chen ML; Ward SLD; Keens T; Khoo MCK. Model-based assessment of cardiovascular autonomic control in children with obstructive sleep apnea. SLEEP 2009

  3. Smelling and Tasting Underwater.

    ERIC Educational Resources Information Center

    Atema, Jelle

    1980-01-01

    Discusses differences between smell and taste, comparing these senses in organisms in aquatic and terrestrial environments. Describes the chemical environment underwater and in air, differences in chemoreceptors to receive stimuli, and the organs, brain, and behavior involved in chemoreception. (CS)

  4. Underwater hydrophone location survey

    NASA Technical Reports Server (NTRS)

    Cecil, Jack B.

    1993-01-01

    The Atlantic Undersea Test and Evaluation Center (AUTEC) is a U.S. Navy test range located on Andros Island, Bahamas, and a Division of the Naval Undersea Warfare Center (NUWC), Newport, RI. The Headquarters of AUTEC is located at a facility in West Palm Beach, FL. AUTEC's primary mission is to provide the U.S. Navy with a deep-water test and evaluation facility for making underwater acoustic measurements, testing and calibrating sonars, and providing accurate underwater, surface, and in-air tracking data on surface ships, submarines, aircraft, and weapon systems. Many of these programs are in support of Antisubmarine Warfare (ASW), undersea research and development programs, and Fleet assessment and operational readiness trials. Most tests conducted at AUTEC require precise underwater tracking (plus or minus 3 yards) of multiple acoustic signals emitted with the correct waveshape and repetition criteria from either a surface craft or underwater vehicle.

  5. Smelling and Tasting Underwater.

    ERIC Educational Resources Information Center

    Atema, Jelle

    1980-01-01

    Discusses differences between smell and taste, comparing these senses in organisms in aquatic and terrestrial environments. Describes the chemical environment underwater and in air, differences in chemoreceptors to receive stimuli, and the organs, brain, and behavior involved in chemoreception. (CS)

  6. Utilizing Underwater Three-Dimensional Modeling to Enhance Ecological and Biological Studies of Coral Reefs

    NASA Astrophysics Data System (ADS)

    Burns, J. H. R.; Delparte, D.; Gates, R. D.; Takabayashi, M.

    2015-04-01

    The structural complexity of coral reefs profoundly affects the biodiversity, productivity, and overall functionality of reef ecosystems. Conventional survey techniques utilize 2-dimensional metrics that are inadequate for accurately capturing and quantifying the intricate structural complexity of scleractinian corals. A 3-dimensional (3D) approach improves the capacity to accurately measure architectural complexity, topography, rugosity, volume, and other structural characteristics that play a significant role in habitat facilitation and ecosystem processes. This study utilized Structure-from-Motion (SfM) photogrammetry techniques to create 3D mesh models for several Hawaiian corals that represent distinct morphological phenotypes. The orthophotos and digital elevation models generated from the SfM process were imported into geospatial analysis software in order to quantify several metrics pertaining to 3D complexity that are known to affect ecosystem biodiversity and productivity. The 3D structural properties of the reconstructed coral colonies were statistically analyzed to determine if the each species represents a unique morpho-functional group. The SfM reconstruction techniques described in this paper can be utilized for an array of research purposes to improve our understanding of how changes in coral composition affect habitat structure and ecological processes in coral reef ecosystems.

  7. Application of H-Infinity Fault Detection to Model-Scale Autonomous Aircraft

    NASA Astrophysics Data System (ADS)

    Vasconcelos, J. F.; Rosa, P.; Kerr, Murray; Latorre Sierra, Antonio; Recupero, Cristina; Hernandez, Lucia

    2015-09-01

    This paper describes the development of a fault detection system for a model scale autonomous aircraft. The considered fault scenario is defined by malfunctions in the elevator, namely bias and stuck-in-place of the surface. The H∞ design methodology is adopted, with an LFT description of the aircraft longitudinal dynamics, that allows for fault detection explicitly synthesized for a wide range of operating airspeeds. The obtained filter is validated in two stages: in a Functional Engineering Simulator (FES), providing preliminary results of the filter performance; and with experimental data, collected in field tests with actual injection of faults in the elevator surface.

  8. Training rats to voluntarily dive underwater: investigations of the mammalian diving response.

    PubMed

    McCulloch, Paul F

    2014-11-12

    Underwater submergence produces autonomic changes that are observed in virtually all diving animals. This reflexly-induced response consists of apnea, a parasympathetically-induced bradycardia and a sympathetically-induced alteration of vascular resistance that maintains blood flow to the heart, brain and exercising muscles. While many of the metabolic and cardiorespiratory aspects of the diving response have been studied in marine animals, investigations of the central integrative aspects of this brainstem reflex have been relatively lacking. Because the physiology and neuroanatomy of the rat are well characterized, the rat can be used to help ascertain the central pathways of the mammalian diving response. Detailed instructions are provided on how to train rats to swim and voluntarily dive underwater through a 5 m long Plexiglas maze. Considerations regarding tank design and procedure room requirements are also given. The behavioral training is conducted in such a way as to reduce the stressfulness that could otherwise be associated with forced underwater submergence, thus minimizing activation of central stress pathways. The training procedures are not technically difficult, but they can be time-consuming. Since behavioral training of animals can only provide a model to be used with other experimental techniques, examples of how voluntarily diving rats have been used in conjunction with other physiological and neuroanatomical research techniques, and how the basic training procedures may need to be modified to accommodate these techniques, are also provided. These experiments show that voluntarily diving rats exhibit the same cardiorespiratory changes typically seen in other diving animals. The ease with which rats can be trained to voluntarily dive underwater, and the already available data from rats collected in other neurophysiological studies, makes voluntarily diving rats a good behavioral model to be used in studies investigating the central aspects of the

  9. Fluid Dynamics of Underwater Flight in Sea Butterflies: Insights from Computational Modeling

    NASA Astrophysics Data System (ADS)

    Zhou, Zhuoyu; Mittal, Rajat; Yen, Jeannette; Webster, Donald

    2014-11-01

    Sea butterflies such as Limacine helicina swim by flapping their wing-like parapodia, in a stroke that exhibits a clap-and-fling type kinematics as well as a strong interaction between the parapodia and the body of the animal at the end of downstroke. We used numerical simulations based on videogrammetric data to examine the fluid dynamics and force generation associated with this swimming motion. The unsteady lift-generating mechanism of clap-and-fling results in a sawtooth trajectory with a characteristic ``wobble'' in pitch. We employ coupled flow-body-dynamics simulations to model the free-swimming motion of the organism and explore the efficiency of propulsion as well the factors such as shell weight, that affect its sawtooth swimming trajectory. This work is funded by NSF Grant 1246317 from the Division of Polar Programs.

  10. Reactive underwater object inspection based on artificial electric sense.

    PubMed

    Lebastard, Vincent; Boyer, Frédéric; Lanneau, Sylvain

    2016-07-26

    Weakly electric fish can perform complex cognitive tasks based on extracting information from blurry electric images projected from their immediate environment onto their electro-sensitive skin. In particular they can be trained to recognize the intrinsic properties of objects such as their shape, size and electric nature. They do this by means of novel perceptual strategies that exploit the relations between the physics of a self-generated electric field, their body morphology and the ability to perform specific movement termed probing motor acts (PMAs). In this article we artificially reproduce and combine these PMAs to build an autonomous control strategy that allows an artificial electric sensor to find electrically contrasted objects, and to orbit around them based on a minimum set of measurements and simple reactive feedback control laws of the probe's motion. The approach does not require any simulation models and could be implemented on an autonomous underwater vehicle (AUV) equipped with artificial electric sense. The AUV has only to satisfy certain simple geometric properties, such as bi-laterally (left/right) symmetrical electrodes and possess a reasonably high aspect (length/width) ratio.

  11. Human Injury Criteria for Underwater Blasts

    PubMed Central

    Lance, Rachel M.; Capehart, Bruce; Kadro, Omar; Bass, Cameron R.

    2015-01-01

    Underwater blasts propagate further and injure more readily than equivalent air blasts. Development of effective personal protection and countermeasures, however, requires knowledge of the currently unknown human tolerance to underwater blast. Current guidelines for prevention of underwater blast injury are not based on any organized injury risk assessment, human data or experimental data. The goal of this study was to derive injury risk assessments for underwater blast using well-characterized human underwater blast exposures in the open literature. The human injury dataset was compiled using 34 case reports on underwater blast exposure to 475 personnel, dating as early as 1916. Using severity ratings, computational reconstructions of the blasts, and survival information from a final set of 262 human exposures, injury risk models were developed for both injury severity and risk of fatality as functions of blast impulse and blast peak overpressure. Based on these human data, we found that the 50% risk of fatality from underwater blast occurred at 302±16 kPa-ms impulse. Conservatively, there is a 20% risk of pulmonary injury at a kilometer from a 20 kg charge. From a clinical point of view, this new injury risk model emphasizes the large distances possible for potential pulmonary and gut injuries in water compared with air. This risk value is the first impulse-based fatality risk calculated from human data. The large-scale inconsistency between the blast exposures in the case reports and the guidelines available in the literature prior to this study further underscored the need for this new guideline derived from the unique dataset of actual injuries in this study. PMID:26606655

  12. Modelling Seasonal Brucellosis Epidemics in Bayingolin Mongol Autonomous Prefecture of Xinjiang, China, 2010-2014.

    PubMed

    Lou, Pengwei; Wang, Lei; Zhang, Xueliang; Xu, Jiabo; Wang, Kai

    2016-01-01

    Brucellosis is one of the severe public health problems; the cumulative number of new human brucellosis cases reached 211515 from 2010 to 2014 in China. Bayingolin Mongol Autonomous Prefecture is situated in the southeast of Xinjiang, where brucellosis infection occurs every year. Based on the reported data of newly acute human brucellosis cases for each season in Bayingolin Mongol Autonomous Prefecture, we proposed a susceptible, exposed, infected, and vaccinated (SEIV) model with periodic transmission rates to investigate the seasonal brucellosis transmission dynamics among sheep/cattle and from sheep/cattle to humans. Compared with the criteria of MAPE and RMSPE, the model simulations agree to the data on newly acute human brucellosis. We predict that the number of newly acute human brucellosis is increasing and will peak 15325 [95% CI: 11920-18242] around the summer of 2023. We also estimate the basic reproduction number R0 = 2.5524 [95% CI: 2.5129-2.6225] and perform some sensitivity analysis of the newly acute human brucellosis cases and the basic reproduction number R0 in terms of model parameters. Our study demonstrates that reducing the birth number of sheep/cattle, raising the slaughter rate of infected sheep/cattle, increasing the vaccination rate of susceptible sheep/cattle, and decreasing the loss rate of vaccination are effective strategies to control brucellosis epidemic.

  13. Modelling Seasonal Brucellosis Epidemics in Bayingolin Mongol Autonomous Prefecture of Xinjiang, China, 2010–2014

    PubMed Central

    Lou, Pengwei; Wang, Lei; Zhang, Xueliang; Xu, Jiabo

    2016-01-01

    Brucellosis is one of the severe public health problems; the cumulative number of new human brucellosis cases reached 211515 from 2010 to 2014 in China. Bayingolin Mongol Autonomous Prefecture is situated in the southeast of Xinjiang, where brucellosis infection occurs every year. Based on the reported data of newly acute human brucellosis cases for each season in Bayingolin Mongol Autonomous Prefecture, we proposed a susceptible, exposed, infected, and vaccinated (SEIV) model with periodic transmission rates to investigate the seasonal brucellosis transmission dynamics among sheep/cattle and from sheep/cattle to humans. Compared with the criteria of MAPE and RMSPE, the model simulations agree to the data on newly acute human brucellosis. We predict that the number of newly acute human brucellosis is increasing and will peak 15325 [95% CI: 11920–18242] around the summer of 2023. We also estimate the basic reproduction number R0 = 2.5524 [95% CI: 2.5129–2.6225] and perform some sensitivity analysis of the newly acute human brucellosis cases and the basic reproduction number R0 in terms of model parameters. Our study demonstrates that reducing the birth number of sheep/cattle, raising the slaughter rate of infected sheep/cattle, increasing the vaccination rate of susceptible sheep/cattle, and decreasing the loss rate of vaccination are effective strategies to control brucellosis epidemic. PMID:27872852

  14. Physics based model for online fault detection in autonomous cryogenic loading system

    SciTech Connect

    Kashani, Ali; Ponizhovskaya, Ekaterina; Luchinsky, Dmitry; Smelyanskiy, Vadim; Patterson-Hine, Anna; Sass, Jared; Brown, Barbara

    2014-01-29

    We report the progress in the development of the chilldown model for a rapid cryogenic loading system developed at NASA-Kennedy Space Center. The nontrivial characteristic feature of the analyzed chilldown regime is its active control by dump valves. The two-phase flow model of the chilldown is approximated as one-dimensional homogeneous fluid flow with no slip condition for the interphase velocity. The model is built using commercial SINDA/FLUINT software. The results of numerical predictions are in good agreement with the experimental time traces. The obtained results pave the way to the application of the SINDA/FLUINT model as a verification tool for the design and algorithm development required for autonomous loading operation.

  15. Pulse-transmission Oscillators: Autonomous Boolean Models and the Yeast Cell Cycle

    NASA Astrophysics Data System (ADS)

    Sevim, Volkan; Gong, Xinwei; Socolar, Joshua

    2010-03-01

    Models of oscillatory gene expression typically involve a constitutively expressed or positively autoregulated gene which is repressed by a negative feedback loop. In Boolean representations of such systems, which include the repressilator and relaxation oscillators, dynamical stability stems from the impossibility of satisfying all of the Boolean rules at once. We consider a different class of networks, in which oscillations are due to the transmission of a pulse of gene activation around a ring. Using autonomous Boolean modeling methods, we show how the circulating pulse can be stabilized by decoration of the ring with certain feedback and feed-forward motifs. We then discuss the relation of these models to ODE models of transcriptional networks, emphasizing the role of explicit time delays. Finally, we show that a network recently proposed as a generator of cell cycle oscillations in yeast contains the motifs required to support stable transmission oscillations.

  16. Where neuroscience and dynamic system theory meet autonomous robotics: a contracting basal ganglia model for action selection.

    PubMed

    Girard, B; Tabareau, N; Pham, Q C; Berthoz, A; Slotine, J-J

    2008-05-01

    Action selection, the problem of choosing what to do next, is central to any autonomous agent architecture. We use here a multi-disciplinary approach at the convergence of neuroscience, dynamical system theory and autonomous robotics, in order to propose an efficient action selection mechanism based on a new model of the basal ganglia. We first describe new developments of contraction theory regarding locally projected dynamical systems. We exploit these results to design a stable computational model of the cortico-baso-thalamo-cortical loops. Based on recent anatomical data, we include usually neglected neural projections, which participate in performing accurate selection. Finally, the efficiency of this model as an autonomous robot action selection mechanism is assessed in a standard survival task. The model exhibits valuable dithering avoidance and energy-saving properties, when compared with a simple if-then-else decision rule.

  17. Zebrafish heart as a model to study the integrative autonomic control of pacemaker function.

    PubMed

    Stoyek, Matthew R; Quinn, T Alexander; Croll, Roger P; Smith, Frank M

    2016-09-01

    The cardiac pacemaker sets the heart's primary rate, with pacemaker discharge controlled by the autonomic nervous system through intracardiac ganglia. A fundamental issue in understanding the relationship between neural activity and cardiac chronotropy is the identification of neuronal populations that control pacemaker cells. To date, most studies of neurocardiac control have been done in mammalian species, where neurons are embedded in and distributed throughout the heart, so they are largely inaccessible for whole-organ, integrative studies. Here, we establish the isolated, innervated zebrafish heart as a novel alternative model for studies of autonomic control of heart rate. Stimulation of individual cardiac vagosympathetic nerve trunks evoked bradycardia (parasympathetic activation) and tachycardia (sympathetic activation). Simultaneous stimulation of both vagosympathetic nerve trunks evoked a summative effect. Effects of nerve stimulation were mimicked by direct application of cholinergic and adrenergic agents. Optical mapping of electrical activity confirmed the sinoatrial region as the site of origin of normal pacemaker activity and identified a secondary pacemaker in the atrioventricular region. Strong vagosympathetic nerve stimulation resulted in a shift in the origin of initial excitation from the sinoatrial pacemaker to the atrioventricular pacemaker. Putative pacemaker cells in the sinoatrial and atrioventricular regions expressed adrenergic β2 and cholinergic muscarinic type 2 receptors. Collectively, we have demonstrated that the zebrafish heart contains the accepted hallmarks of vertebrate cardiac control, establishing this preparation as a viable model for studies of integrative physiological control of cardiac function by intracardiac neurons. Copyright © 2016 the American Physiological Society.

  18. Zebrafish heart as a model to study the integrative autonomic control of pacemaker function

    PubMed Central

    Stoyek, Matthew R.; Quinn, T. Alexander; Croll, Roger P.

    2016-01-01

    The cardiac pacemaker sets the heart's primary rate, with pacemaker discharge controlled by the autonomic nervous system through intracardiac ganglia. A fundamental issue in understanding the relationship between neural activity and cardiac chronotropy is the identification of neuronal populations that control pacemaker cells. To date, most studies of neurocardiac control have been done in mammalian species, where neurons are embedded in and distributed throughout the heart, so they are largely inaccessible for whole-organ, integrative studies. Here, we establish the isolated, innervated zebrafish heart as a novel alternative model for studies of autonomic control of heart rate. Stimulation of individual cardiac vagosympathetic nerve trunks evoked bradycardia (parasympathetic activation) and tachycardia (sympathetic activation). Simultaneous stimulation of both vagosympathetic nerve trunks evoked a summative effect. Effects of nerve stimulation were mimicked by direct application of cholinergic and adrenergic agents. Optical mapping of electrical activity confirmed the sinoatrial region as the site of origin of normal pacemaker activity and identified a secondary pacemaker in the atrioventricular region. Strong vagosympathetic nerve stimulation resulted in a shift in the origin of initial excitation from the sinoatrial pacemaker to the atrioventricular pacemaker. Putative pacemaker cells in the sinoatrial and atrioventricular regions expressed adrenergic β2 and cholinergic muscarinic type 2 receptors. Collectively, we have demonstrated that the zebrafish heart contains the accepted hallmarks of vertebrate cardiac control, establishing this preparation as a viable model for studies of integrative physiological control of cardiac function by intracardiac neurons. PMID:27342878

  19. Omnidirectional Underwater Camera Design and Calibration

    PubMed Central

    Bosch, Josep; Gracias, Nuno; Ridao, Pere; Ribas, David

    2015-01-01

    This paper presents the development of an underwater omnidirectional multi-camera system (OMS) based on a commercially available six-camera system, originally designed for land applications. A full calibration method is presented for the estimation of both the intrinsic and extrinsic parameters, which is able to cope with wide-angle lenses and non-overlapping cameras simultaneously. This method is valid for any OMS in both land or water applications. For underwater use, a customized housing is required, which often leads to strong image distortion due to refraction among the different media. This phenomena makes the basic pinhole camera model invalid for underwater cameras, especially when using wide-angle lenses, and requires the explicit modeling of the individual optical rays. To address this problem, a ray tracing approach has been adopted to create a field-of-view (FOV) simulator for underwater cameras. The simulator allows for the testing of different housing geometries and optics for the cameras to ensure a complete hemisphere coverage in underwater operation. This paper describes the design and testing of a compact custom housing for a commercial off-the-shelf OMS camera (Ladybug 3) and presents the first results of its use. A proposed three-stage calibration process allows for the estimation of all of the relevant camera parameters. Experimental results are presented, which illustrate the performance of the calibration method and validate the approach. PMID:25774707

  20. Omnidirectional underwater camera design and calibration.

    PubMed

    Bosch, Josep; Gracias, Nuno; Ridao, Pere; Ribas, David

    2015-03-12

    This paper presents the development of an underwater omnidirectional multi-camera system (OMS) based on a commercially available six-camera system, originally designed for land applications. A full calibration method is presented for the estimation of both the intrinsic and extrinsic parameters, which is able to cope with wide-angle lenses and non-overlapping cameras simultaneously. This method is valid for any OMS in both land or water applications. For underwater use, a customized housing is required, which often leads to strong image distortion due to refraction among the different media. This phenomena makes the basic pinhole camera model invalid for underwater cameras, especially when using wide-angle lenses, and requires the explicit modeling of the individual optical rays. To address this problem, a ray tracing approach has been adopted to create a field-of-view (FOV) simulator for underwater cameras. The simulator allows for the testing of different housing geometries and optics for the cameras to ensure a complete hemisphere coverage in underwater operation. This paper describes the design and testing of a compact custom housing for a commercial off-the-shelf OMS camera (Ladybug 3) and presents the first results of its use. A proposed three-stage calibration process allows for the estimation of all of the relevant camera parameters. Experimental results are presented, which illustrate the performance of the calibration method and validate the approach.

  1. Underwater speech communications with a modulated laser

    NASA Astrophysics Data System (ADS)

    Woodward, B.; Sari, H.

    2008-04-01

    A novel speech communications system using a modulated laser beam has been developed for short-range applications in which high directionality is an exploitable feature. Although it was designed for certain underwater applications, such as speech communications between divers or between a diver and the surface, it may equally be used for air applications. With some modification it could be used for secure diver-to-diver communications in the situation where untethered divers are swimming close together and do not want their conversations monitored by intruders. Unlike underwater acoustic communications, where the transmitted speech may be received at ranges of hundreds of metres omnidirectionally, a laser communication link is very difficult to intercept and also obviates the need for cables that become snagged or broken. Further applications include the transmission of speech and data, including the short message service (SMS), from a fixed installation such as a sea-bed habitat; and data transmission to and from an autonomous underwater vehicle (AUV), particularly during docking manoeuvres. The performance of the system has been assessed subjectively by listening tests, which revealed that the speech was intelligible, although of poor quality due to the speech algorithm used.

  2. Underwater photogrammetric theoretical equations and technique

    NASA Astrophysics Data System (ADS)

    Fan, Ya-bing; Huang, Guiping; Qin, Gui-qin; Chen, Zheng

    2011-12-01

    In order to have a high level of accuracy of measurement in underwater close-range photogrammetry, this article deals with a study of three varieties of model equations according to the way of imaging upon the water. First, the paper makes a careful analysis for the two varieties of theoretical equations and finds out that there are some serious limitations in practical application and has an in-depth study for the third model equation. Second, one special project for this measurement has designed correspondingly. Finally, one rigid antenna has been tested by underwater photogrammetry. The experimental results show that the precision of 3D coordinates measurement is 0.94mm, which validates the availability and operability in practical application with this third equation. It can satisfy the measurement requirements of refraction correction, improving levels of accuracy of underwater close-range photogrammetry, as well as strong antijamming and stabilization.

  3. Remote repair grinding of cracks underwater

    SciTech Connect

    Thomessen, T.; Lien, T.K.; Johnsen, K.

    1994-12-31

    This paper presents a new approach for remote repair grinding of cracks underwater. The approach uses Controlled Material Removal Rate (CMRR) grinding strategy which is based on a force controlled manipulator for handling the grinding machine. The CMRR-strategy requires an empirical model of the grinding process. Different grinding wheels were tested in underwater grinding, and experiments were carried out to derived an empirical model of the grinding process for a cylindrical grinding wheel. Finally, the CMRR-strategy was applied to grind a groove according to given specifications. The force control system was used to measure the groove geometry after grinding. The results were promising and demonstrate clearly that the CMRR-strategy is very useful in underwater grinding due to its high flexibility.

  4. Visual-adaptation-mechanism based underwater object extraction

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Wang, Huibin; Xu, Lizhong; Shen, Jie

    2014-03-01

    Due to the major obstacles originating from the strong light absorption and scattering in a dynamic underwater environment, underwater optical information acquisition and processing suffer from effects such as limited range, non-uniform lighting, low contrast, and diminished colors, causing it to become the bottleneck for marine scientific research and projects. After studying and generalizing the underwater biological visual mechanism, we explore its advantages in light adaption which helps animals to precisely sense the underwater scene and recognize their prey or enemies. Then, aiming to transform the significant advantage of the visual adaptation mechanism into underwater computer vision tasks, a novel knowledge-based information weighting fusion model is established for underwater object extraction. With this bionic model, the dynamical adaptability is given to the underwater object extraction task, making them more robust to the variability of the optical properties in different environments. The capability of the proposed method to adapt to the underwater optical environments is shown, and its outperformance for the object extraction is demonstrated by comparison experiments.

  5. Model-Unified Planning and Execution for Distributed Autonomous System Control

    NASA Technical Reports Server (NTRS)

    Aschwanden, Pascal; Baskaran, Vijay; Bernardini, Sara; Fry, Chuck; Moreno, Maria; Muscettola, Nicola; Plaunt, Chris; Rijsman, David; Tompkins, Paul

    2006-01-01

    The Intelligent Distributed Execution Architecture (IDEA) is a real-time architecture that exploits artificial intelligence planning as the core reasoning engine for interacting autonomous agents. Rather than enforcing separate deliberation and execution layers, IDEA unifies them under a single planning technology. Deliberative and reactive planners reason about and act according to a single representation of the past, present and future domain state. The domain state behaves the rules dictated by a declarative model of the subsystem to be controlled, internal processes of the IDEA controller, and interactions with other agents. We present IDEA concepts - modeling, the IDEA core architecture, the unification of deliberation and reaction under planning - and illustrate its use in a simple example. Finally, we present several real-world applications of IDEA, and compare IDEA to other high-level control approaches.

  6. Model-Unified Planning and Execution for Distributed Autonomous System Control

    NASA Technical Reports Server (NTRS)

    Aschwanden, Pascal; Baskaran, Vijay; Bernardini, Sara; Fry, Chuck; Moreno, Maria; Muscettola, Nicola; Plaunt, Chris; Rijsman, David; Tompkins, Paul

    2006-01-01

    The Intelligent Distributed Execution Architecture (IDEA) is a real-time architecture that exploits artificial intelligence planning as the core reasoning engine for interacting autonomous agents. Rather than enforcing separate deliberation and execution layers, IDEA unifies them under a single planning technology. Deliberative and reactive planners reason about and act according to a single representation of the past, present and future domain state. The domain state behaves the rules dictated by a declarative model of the subsystem to be controlled, internal processes of the IDEA controller, and interactions with other agents. We present IDEA concepts - modeling, the IDEA core architecture, the unification of deliberation and reaction under planning - and illustrate its use in a simple example. Finally, we present several real-world applications of IDEA, and compare IDEA to other high-level control approaches.

  7. Design of a dynamic model of genes with multiple autonomous regulatory modules by evolutionary computations

    PubMed Central

    Spirov, Alexander V.; Holloway, David M.

    2010-01-01

    A new approach to design a dynamic model of genes with multiple autonomous regulatory modules by evolutionary computations is proposed. The approach is based on Genetic Algorithms (GA), with new crossover operators especially designed for these purposes. The new operators use local homology between parental strings to preserve building blocks found by the algorithm. The approach exploits the subbasin-portal architecture of the fitness functions suitable for this kind of evolutionary modeling. This architecture is significant for Royal Road class fitness functions. Two real-life Systems Biology problems with such fitness functions are implemented here: evolution of the bacterial promoter rrnPl and of the enhancer of the Drosophila even-skipped gene. The effectiveness of the approach compared to standard GA is demonstrated on several benchmark and real-life tasks. PMID:20930945

  8. Underwater Acoustic Carbon Nanotube Thermophone

    DTIC Science & Technology

    2016-09-23

    Attorney Docket No. 300042 1 of 10 UNDERWATER ACOUSTIC CARBON NANOTUBE THERMOPHONE STATEMENT OF GOVERNMENT INTEREST [0001] The invention...the Invention [0003] The present invention is an acoustically transparent carbon nanotube underwater acoustic source which acts as a thermophone...development of underwater acoustic carbon nanotube (CNT) yarn sheets capable of producing high acoustic output at low frequencies with broad bandwidth. An

  9. Resources for Underwater Robotics Education

    ERIC Educational Resources Information Center

    Wallace, Michael L.; Freitas, William M.

    2016-01-01

    4-H clubs can build and program underwater robots from raw materials. An annotated resource list for engaging youth in building underwater remotely operated vehicles (ROVs) is provided. This article is a companion piece to the Research in Brief article "Building Teen Futures with Underwater Robotics" in this issue of the "Journal of…

  10. Resources for Underwater Robotics Education

    ERIC Educational Resources Information Center

    Wallace, Michael L.; Freitas, William M.

    2016-01-01

    4-H clubs can build and program underwater robots from raw materials. An annotated resource list for engaging youth in building underwater remotely operated vehicles (ROVs) is provided. This article is a companion piece to the Research in Brief article "Building Teen Futures with Underwater Robotics" in this issue of the "Journal of…

  11. [Autonomic neuropathies].

    PubMed

    Siepmann, T; Penzlin, A I; Illigens, B M W

    2013-07-01

    Autonomic neuropathies are a heterogeneous group of diseases that involve damage of small peripheral autonomic Aδ- and C-fibers. Causes of autonomic nerve fiber damage are disorders such as diabetes mellitus and HIV-infection. Predominant symptoms of autonomic neuropathy are orthostatic hypotension, gastro-intestinal problems, urogenital dysfunction, and cardiac arrhythmia, which can severely impair the quality of life in affected patients. Furthermore, autonomic neuropathies can be induced by autoimmune diseases such as acute inflammatory demyelinating polyneuropathy, hereditary disorders such as the lysosomal storage disorder Fabry disease and hereditary sensory and autonomic neuropathies, as well as certain toxins and drugs. © Georg Thieme Verlag KG Stuttgart · New York.

  12. Design and Analysis of Underwater Acoustic Networks with Reflected Links

    NASA Astrophysics Data System (ADS)

    Emokpae, Lloyd

    Underwater acoustic networks (UWANs) have applications in environmental state monitoring, oceanic profile measurements, leak detection in oil fields, distributed surveillance, and navigation. For these applications, sets of nodes are employed to collaboratively monitor an area of interest and track certain events or phenomena. In addition, it is common to find autonomous underwater vehicles (AUVs) acting as mobile sensor nodes that perform search-and-rescue missions, reconnaissance in combat zones, and coastal patrol. These AUVs are to work cooperatively to achieve a desired goal and thus need to be able to, in an ad-hoc manner, establish and sustain communication links in order to ensure some desired level of quality of service. Therefore, each node is required to adapt to environmental changes and be able to overcome broken communication links caused by external noise affecting the communication channel due to node mobility. In addition, since radio waves are quickly absorbed in the water medium, it is common for most underwater applications to rely on acoustic (or sound) rather than radio channels for mid-to-long range communications. However, acoustic channels pose multiple challenging issues, most notably the high transmission delay due to slow signal propagation and the limited channel bandwidth due to high frequency attenuation. Moreover, the inhomogeneous property of the water medium affects the sound speed profile while the signal surface and bottom reflections leads to multipath effects. In this dissertation, we address these networking challenges by developing protocols that take into consideration the underwater physical layer dynamics. We begin by introducing a novel surface-based reflection scheme (SBR), which takes advantage of the multipath effects of the acoustic channel. SBR works by using reflections from the water surface, and bottom, to establish non-line-of-sight (NLOS) communication links. SBR makes it possible to incorporate both line

  13. Improving fundamental factors among correlation matching algorithms in underwater TANS

    NASA Astrophysics Data System (ADS)

    Lin, Yi; Yan, Lei; Tong, Qingxi

    2007-06-01

    TERCOM, ICP and TIEM algorithms, which mathematically all apply correlation matching mode, have been developed for positioning in underwater Terrain-aided Navigation System (TANS), but how to virtually improve their performance is still research puzzle now. Analyzing the characters of terrain reference data's distribution and vehicles prowling underwater, we find that grid spacing and accumulation sequence are two decisional elements of underwater TANS. Then the modified Maximum a Posteriori (MAP) estimation algorithm (M-MAP) from super-resolution images reconstruction is creatively explored for implementing interpolation to enhance the accuracy of non-surveyed points' deep-determination, and basic error mechanism model (EMM) based on Mean Absolute Difference (MAD) algorithm is deduced which can reflect the relationship of underwater TANS's inner factors. Simulation experiments indicate that adopting appropriate fundamental factors can effectively boost up underwater TANS's navigation competence based on the algorithms listed above.

  14. A simulation model of biofilms with autonomous cells: analysis of a two-dimensional version

    NASA Astrophysics Data System (ADS)

    Tatek, Yergou; Slater, Gary

    2004-03-01

    We introduce a novel model for simulating biofilms growth based on individual cells. Each cell is modelled as an autonomous agent whose behavior is controlled by thermodynamic parameters, mechanical properties and environmental factors. In the two-dimensional version presented here, a cell is represented by a closed chain of self-avoiding beads linked together using the bond fluctuation algorithm. The cell is thus controlled both by the rigidity of its membrane and its internal pressure. The model is complemented by key features such as the explicit inclusion of the so-called extra polymeric substance (EPS), the explicit presence of nutrient diffusion and flow, the processes of cell division and death and the attractive interactions between the cell (and / or the EPS) and the surface on which the colony grows. As the model is intended to integrate cellular processes into a generic population model, tuning the parameters of the model can lead to the growth and maturation of various types of biofilms.

  15. The Trans-Contextual Model of Autonomous Motivation in Education: Conceptual and Empirical Issues and Meta-Analysis.

    PubMed

    Hagger, Martin S; Chatzisarantis, Nikos L D

    2016-06-01

    The trans-contextual model outlines the processes by which autonomous motivation toward activities in a physical education context predicts autonomous motivation toward physical activity outside of school, and beliefs about, intentions toward, and actual engagement in, out-of-school physical activity. In the present article, we clarify the fundamental propositions of the model and resolve some outstanding conceptual issues, including its generalizability across multiple educational domains, criteria for its rejection or failed replication, the role of belief-based antecedents of intentions, and the causal ordering of its constructs. We also evaluate the consistency of model relationships in previous tests of the model using path-analytic meta-analysis. The analysis supported model hypotheses but identified substantial heterogeneity in the hypothesized relationships across studies unattributed to sampling and measurement error. Based on our meta-analysis, future research needs to provide further replications of the model in diverse educational settings beyond physical education and test model hypotheses using experimental methods.

  16. Adaptive Target Tracking for Underwater Maneuvering Targets.

    DTIC Science & Technology

    1979-12-01

    Gholson and Moose [5] to three-dimensional tracking. The general approach which uses the "adaptive semi-Markov man- euver model" of [4] and [5] implies a...of a maneuvering target (U)," U.S. Naval J. Underwater Acoustics, July 1973. [51 N. H. Gholson and R. L. Moose, "Maneuvering target tracking using

  17. Periodic solution for a stochastic non-autonomous competitive Lotka-Volterra model in a polluted environment

    NASA Astrophysics Data System (ADS)

    Jiang, Daqing; Zhang, Qiumei; Hayat, Tasawar; Alsaedi, Ahmed

    2017-04-01

    In this paper, we consider a stochastic non-autonomous competitive Lotka-Volterra model in a polluted environment. We derive sufficient criteria for the existence and global attractivity of the boundary periodic solutions. Furthermore, we obtain conditions for the existence and global attractivity of a nontrivial positive periodic solution. Finally we make simulations to illustrate our analytical results.

  18. The Autonomous-collaborative Care Model: meeting the future head on.

    PubMed

    LeClerc, Chantale Marie; Doyon, Julie; Gravelle, Debbie; Hall, Bonnie; Roussel, Josette

    2008-01-01

    As care needs continue to increase in complexity in inpatient settings, and nurses' scope of practice evolves to keep pace with these changing demands, it is imperative that nurse leaders ensure nursing care delivery models are well aligned to current realities. Older, traditional models of nursing service may no longer foster safe, effective and efficient care or contribute to job satisfaction and high-quality work life for nurses. This paper describes the Autonomous-Collaborative Care Model and its application in a continuing care setting. This innovative and flexible model fosters autonomy and accountability in nursing practice, reduces duplication in the execution of nursing tasks, enhances effective communication and outlines mechanisms for collaboration among various members of the nursing and interprofessional teams. The model has positioned the authors' organization to meet impending shortages of nursing personnel by ensuring that the right category of nurse is assigned to the appropriate patient, by reducing non-nursing work and by supporting nurses' autonomy to practise to their full scope.

  19. A simulation model of biofilms with autonomous cells: I. Analysis of a two-dimensional version

    NASA Astrophysics Data System (ADS)

    Tatek, Yergou B.; Slater, Gary W.

    2006-04-01

    We introduce a single-cell based simulation model of biofilm growth. Each microbial cell is modelled as an autonomous agent whose behavior is controlled by thermodynamic parameters, mechanical properties, physiological rules and environmental conditions. In the two-dimensional version presented here, a cell is represented by a closed chain of self-avoiding beads linked together using the bond fluctuation algorithm. The cell is thus controlled both by the rigidity of its membrane and a pressure difference. The model is complemented by key features such as the explicit presence of nutrient diffusion and flow, the processes of cell-division and cell-death, and the attractive interactions between the cell and the surface on which the colony grows. Tuning the parameters of the model can lead to the growth and maturation of various types of biofilms. In this first article, we describe the main properties of a two-dimensional version of the model, and we discuss the extension to three dimensions.

  20. Diversity in underwater inspection

    SciTech Connect

    Goldberg, L.

    1996-03-01

    Underwater nondestructive testing (NDT) of deepwater structures provides a diverse, hostile, and challenging means to implement NDT. Given a warm, shallow water with good visibility, working underwater approaches the category of ``I get paid for this.`` This environment allows for identical reliability as ``topside`` NDT. Underwater visual, magnetic particle, and ultrasonic testing have been in place since the early 1980s, with equipment modified for submergence and closely resembling topside NDT tools. However, deepwater structures represent the most unique of NDT considerations. In the Gulf of Mexico, there are approximately 15 fixed structures installed at a depth of 243--400 m. This article describes safety, technical, and commercial issues relating to inspecting deepwater structures and focuses especially on a comparison of remote operated vehicles (ROVs) and atmospheric diving suits (ADSs). Deepwater structures have excellent records of structural integrity with an extremely low incidence of corrosion or fatigue cracking problems. The primary reason for developing deepwater NDT capabilities is contingency for damage during installation impact damage from dropped objects. There are three means used for underwater NDT: diving, atmospheric diving suits (ADSs), and remotely operated vehicles (ROVs).

  1. Autonomous control

    NASA Technical Reports Server (NTRS)

    Brown, Barbara

    1990-01-01

    KSC has been developing the Knowledge-Based Autonomous Test Engineer (KATE), which is a tool for performing automated monitoring, diagnosis, and control of electromechanical devices. KATE employs artificial intelligence computing techniques to perform these functions. The KATE system consists of a generic shell and a knowledge base. The KATE shell is the portion of the system which performs the monitoring, diagnosis, and control functions. It is generic in the sense that it is application independent. This means that the monitoring activity, for instance, will be performed with the same algorithms regardless of the particular physical device being used. The knowledge base is the portion of the system which contains specific functional and behavorial information about the physical device KATE is working with. Work is nearing completion on a project at KSC to interface a Texas Instruments Explorer running a LISP version of KATE with a Generic Checkout System (GCS) test-bed to control a physical simulation of a shuttle tanking system (humorously called the Red Wagon because of its color and mobility). The Autonomous Control System (ACS) project supplements and extends the KATE/GCS project by adding three other major activities. The activities include: porting KATE from the Texas Instruments Explorer machine to an Intel 80386-based UNIX workstation in the LISP language; rewriting KATE as necessary to run on the same 80386 workstation but in the Ada language; and investigating software and techniques to translate ANSI Standard Common LISP to Mil Standard Ada. Primary goals of this task are as follows: (1) establish the advantages of using expert systems to provide intelligent autonomous software for Space Station Freedom applications; (2) determine the feasibility of using Ada as the run-time environment for model-based expert systems; (3) provide insight into the advantages and disadvantagesof using LISP or Ada in the run-time environment for expert systems; and (4

  2. Time-Dependent Modeling of Underwater Explosions by Convolving Similitude Source with Bandlimited Impulse from the CASS/GRAB Model

    DTIC Science & Technology

    2015-06-30

    with the farfield impulse response from the Comprehensive Acoustic System Simulation/Gaussian Ray Acoustic Bundle (CASS/GRAB) model. The impulse...Comprehensive Acoustic System Simulation/Gaussian Ray Acoustic Bundle (CASS/GRAB) Model Time-Dependent Computational Model Green’s Function Time...GRAB Comprehensive Acoustic System Simulation/Gaussian Ray Acoustic Bundle CW Continuous wave ESA Endangered Species Act FFT Fast Fourier

  3. Autonomic nervous system regulation of the sinoatrial cell depolarization rate: Unifying computational models.

    PubMed

    Castellanos, P; Godinez, R

    2015-01-01

    In the last years different computational models have been proposed to simulate the sinoatrial node cell (SANC) action potential. Also, there has been a great effort to model the heart regulation mechanism by the autonomic nervous system (ANS) through the sympathetic and parasympathetic pathways. Both computational models have tried to fit the rabbit and/or the guinea-pig experimental heart rate data with an increasing success. Thus, the aim of this work was to unify the available models that have been reported to study the heart rate behavior when the SANC is stimulated by using different frequency patterns. Our results contribute to the unification of part of the Scepanovic's model [1] (involved with second messengers dynamics and its influence over specific SANC ionic channels), and the SANC ionic channels computational model proposed by Severi et al. [2] in 2012. In this model unification we did refit some parameters, particularly, those related to the Hill functions in the dynamic modeling of phosphokinase and its effect on the ionic channels currents If and ICaL, and over the Pup, parameter that is related to the Ca(++) uptake by the sarcoplasmic reticulum. Also, we eliminated the neurotransmitter effect over the ionic current IKr that is not presented in the Severi's model. These modifications were enough to successfully reproduce the heart rate experimental recordings under acetylcholine (Ach) or norepinephrine (NE) for independent stimulation: Ach 10 nM stimulation showed a 21.54% action potential shift compared with the 20% reported for experimental recordings; Isoprenaline 1 μM, also displayed a depolarization increased rate of 29.3%, compared with the experimental data of 28.2%. Furthermore, we were able to reproduce the guinea-pig experimental heart rate recordings, when the SANC model was vagal stimulated by using a 2 Hz, 10 Hz and 20 Hz frequency for 10 seconds and the experimental heart rate data for a sympathetic stimulation of 10 Hz frequency for

  4. EXERCISE PREVENTS DEVELOPMENT OF AUTONOMIC DYSREGULATION AND HYPERALGESIA IN A MOUSE MODEL OF CHRONIC MUSCLE PAIN

    PubMed Central

    Sabharwal, Rasna; Rasmussen, Lynn; Sluka, Kathleen A.; Chapleau, Mark W.

    2015-01-01

    Chronic musculoskeletal pain (CMP) conditions, like fibromyalgia, are associated with widespread pain and alterations in autonomic function. Regular physical activity prevents development of CMP and can reduce autonomic dysfunction. We tested if there were alterations in autonomic function in sedentary mice with CMP, and if exercise reduced the autonomic dysfunction and pain induced by CMP. CMP was induced by two intramuscular injections of pH 5 in combination with a single fatiguing exercise task. A running wheel was placed into cages so that the mouse had free access for either 5 days or 8 weeks (exercise groups) and these animals were compared to sedentary mice without running wheels. Autonomic function and nociceptive withdrawal thresholds of the paw and muscle were assessed before and after induction of CMP in exercised and sedentary mice. In sedentary mice, we show decreased baroreflex sensitivity, increased blood pressure variability, decreased heart rate variability and decreased withdrawal thresholds of the paw and muscle 24h after induction of CMP. There were no sex differences after induction of the CMP in any outcome measure. We further show that both 5 days and 8 weeks of physical activity prevent the development of autonomic dysfunction and decreases in withdrawal threshold induced by CMP. Thus, this study uniquely shows development of autonomic dysfunction in animals with chronic muscle hyperalgesia that can be prevented with as little as 5 days of physical activity, and suggest that physical activity may prevent the development of pain and autonomic dysfunction in people with CMP. PMID:26313406

  5. Flatness-based adaptive fuzzy control of an autonomous submarine model

    NASA Astrophysics Data System (ADS)

    Rigatos, Gerasimos; Siano, Pierluigi; Raffo, Guilherme

    2015-12-01

    The article presents a differential flatness theory-based method for adaptive control of autonomous submarines. A proof is provided about the differential flatness properties of the submarine's model (having as state variables the vessel's depth and its pitch angle). This also means that all its state variables and its control inputs can be written as differential functions of the flat output. Making use of its differential flatness features, the submarine's dynamic model is transformed into the multivariable linear canonical (Brunovsky) form. In the transformed model, the control inputs consist of unknown nonlinear parts, which are identified with the use of neurofuzzy approximators. The learning rate for these estimators is determined by the requirement the first derivative of the closed-loop's Lyapunov function to be a negative one. Furthermore, with the use of Lyapunov stability analysis it is proven that an H-infinity tracking performance is succeeded for the feedback control loop. This implies enhanced robustness to model uncertainty and to external perturbations. Simulation experiments are carried out to further confirm the efficiency of the proposed adaptive fuzzy control scheme.

  6. Cytoskeletal turnover and Myosin contractility drive cell autonomous oscillations in a model of Drosophila Dorsal Closure

    NASA Astrophysics Data System (ADS)

    Machado, P. F.; Blanchard, G. B.; Duque, J.; Gorfinkiel, N.

    2014-06-01

    Oscillatory behaviour in force-generating systems is a pervasive phenomenon in cell biology. In this work, we investigate how oscillations in the actomyosin cytoskeleton drive cell shape changes during the process of Dorsal Closure (DC), a morphogenetic event in Drosophila embryo development whereby epidermal continuity is generated through the pulsatile apical area reduction of cells constituting the amnioserosa (AS) tissue. We present a theoretical model of AS cell dynamics by which the oscillatory behaviour arises due to a coupling between active myosin-driven forces, actin turnover and cell deformation. Oscillations in our model are cell-autonomous and are modulated by neighbour coupling, and our model accurately reproduces the oscillatory dynamics of AS cells and their amplitude and frequency evolution. A key prediction arising from our model is that the rate of actin turnover and Myosin contractile force must increase during DC in order to reproduce the decrease in amplitude and period of cell area oscillations observed in vivo. This prediction opens up new ways to think about the molecular underpinnings of AS cell oscillations and their link to net tissue contraction and suggests the form of future experimental measurements.

  7. Communication and cooperation in underwater acoustic networks

    NASA Astrophysics Data System (ADS)

    Yerramalli, Srinivas

    In this thesis, we present a study of several problems related to underwater point to point communications and network formation. We explore techniques to improve the achievable data rate on a point to point link using better physical layer techniques and then study sensor cooperation which improves the throughput and reliability in an underwater network. Robust point-to-point communications in underwater networks has become increasingly critical in several military and civilian applications related to underwater communications. We present several physical layer signaling and detection techniques tailored to the underwater channel model to improve the reliability of data detection. First, a simplified underwater channel model in which the time scale distortion on each path is assumed to be the same (single scale channel model in contrast to a more general multi scale model). A novel technique, which exploits the nature of OFDM signaling and the time scale distortion, called Partial FFT Demodulation is derived. It is observed that this new technique has some unique interference suppression properties and performs better than traditional equalizers in several scenarios of interest. Next, we consider the multi scale model for the underwater channel and assume that single scale processing is performed at the receiver. We then derive optimized front end pre-processing techniques to reduce the interference caused during single scale processing of signals transmitted on a multi-scale channel. We then propose an improvised channel estimation technique using dictionary optimization methods for compressive sensing and show that significant performance gains can be obtained using this technique. In the next part of this thesis, we consider the problem of sensor node cooperation among rational nodes whose objective is to improve their individual data rates. We first consider the problem of transmitter cooperation in a multiple access channel and investigate the stability of

  8. Polarimetric imaging and retrieval of target polarization characteristics in underwater environment.

    PubMed

    Gu, Yalong; Carrizo, Carlos; Gilerson, Alexander A; Brady, Parrish C; Cummings, Molly E; Twardowski, Michael S; Sullivan, James M; Ibrahim, Amir I; Kattawar, George W

    2016-01-20

    Polarized light fields contain more information than simple irradiance and such capabilities provide an advanced tool for underwater imaging. The concept of the beam spread function (BSF) for analysis of scalar underwater imaging was extended to a polarized BSF which considers polarization. The following studies of the polarized BSF in an underwater environment through Monte Carlo simulations and experiments led to a simplified underwater polarimetric imaging model. With the knowledge acquired in the analysis of the polarimetric imaging formation process of a manmade underwater target with known polarization properties, a method to extract the inherent optical properties of the water and to retrieve polarization characteristics of the target was explored. The proposed method for retrieval of underwater target polarization characteristics should contribute to future efforts to reveal the underlying mechanism of polarization camouflage possessed by marine animals and finally to generalize guidelines for creating engineered surfaces capable of similar polarization camouflage abilities in an underwater environment.

  9. The influence of oxazaphosphorines alkylating agents on autonomic nervous system activity in rat experimental cystitis model.

    PubMed

    Dobrek, Łukasz; Baranowska, Agnieszka; Thor, Piotr J

    2013-01-01

    The oxazaphosphorines alkylating agents (cyclophosphamide; CP and ifosfamide; IF) are often used in common clinical practice. However, treatment with CP/IF is burdened with the risk of many adverse drug reactions, especially including hemorrhagic cystitis (HC) that is associated with bladder overactivity symptoms (OAB). The HC pathophysiology is still not fully displayed; it seems that autonomic nervous system (ANS) functional abnormalities play important role in this disturbance. The aim of our study was to reveal the potential ANS differences in rat experimental HC model, evoked by CP and IF by an indirect ANS assessment--heart rate variability (HRV) study. We carried out our experimental research in three essential groups: control group (group 1), cyclophosphamide-induced HC (CP-HC; group 2) one and ifosfamide-induced HC (IF-HC; group 3) one. CP was i.p. administrated four times in dose of 75 mg/kg body weight while IF-treated rats received i.p. five drug doses; 50 mg/kg body weight. Control rats were administrated i.p. vehicle in appropriate volumes as CP/IF treated animals. HRV studies were performed the next day after the last oxazaphosphorines dose. Standard time- and spectral (frequency) domain parameters were estimated. We confirmed the HC development after both CP/IF in macroscopic assessment and bladder wet weight measurement; however, it was more aggravated in CP-HC group. Moreover, we demonstrated HRV disturbances, suggesting ANS impairment after both studied oxazaphosphorines, however, consistent with the findings mentioned above, the autonomic dysfunction was more emphasized after CP. CP treatment was also associated with changes of non-normalized HRV spectral components percentage distribution--a marked very low frequency--VLF [%] increase together with low frequency--LF [%] and high frequency--HF [%] decrease were observed. Taking into consideration the next findings, demonstrating the lack of both normalized power spectral components (nLF and n

  10. Autonomic dysregulation and the Window of Tolerance model of the effects of complex emotional trauma.

    PubMed

    Corrigan, F M; Fisher, J J; Nutt, D J

    2011-01-01

    This paper reviews the Window of Tolerance model of the long-term effects of the severe emotional trauma associated with childhood abuse, a model which can also be applied to adult trauma of sufficient severity to cause post-traumatic stress disorder, chronic dysthymic disorders and chronic anxiety disorders. Dysfunctional behaviours such as deliberate self-harm and substance abuse are seen as efforts to regulate an autonomic nervous system which is readily triggered into extreme states by reminders of the original traumatic events. While midbrain areas such as the periaqueductal gray mediate instant defence responses to traumatic events and their memory triggers it is proposed that ascending monoaminergic tracts are implicated in longer-term changes in mood and arousal. An imbalance of ascending dopaminergic tracts may drive rapid fluctuations in level of arousal and in the associated mood, drive and motivation. Animal models of depression frequently use traumatic experiences of pain, isolation or social defeat to induce changes in mesolimbic and mesocortical dopamine systems which may alter prefrontal cortical control of midbrain defence responses. A focus on the pharmacology of the Window of Tolerance could provide advances in drug treatments for promoting emotional regulation in those who are suffering from the chronic sequelae of traumatic experiences.

  11. Autonomous Modeling, Statistical Complexity and Semi-annealed Treatment of Boolean Networks

    NASA Astrophysics Data System (ADS)

    Gong, Xinwei

    This dissertation presents three studies on Boolean networks. Boolean networks are a class of mathematical systems consisting of interacting elements with binary state variables. Each element is a node with a Boolean logic gate, and the presence of interactions between any two nodes is represented by directed links. Boolean networks that implement the logic structures of real systems are studied as coarse-grained models of the real systems. Large random Boolean networks are studied with mean field approximations and used to provide a baseline of possible behaviors of large real systems. This dissertation presents one study of the former type, concerning the stable oscillation of a yeast cell-cycle oscillator, and two studies of the latter type, respectively concerning the statistical complexity of large random Boolean networks and an extension of traditional mean field techniques that accounts for the presence of short loops. In the cell-cycle oscillator study, a novel autonomous update scheme is introduced to study the stability of oscillations in small networks. A motif that corrects pulse-growing perturbations and a motif that grows pulses are identified. A combination of the two motifs is capable of sustaining stable oscillations. Examining a Boolean model of the yeast cell-cycle oscillator using an autonomous update scheme yields evidence that it is endowed with such a combination. Random Boolean networks are classified as ordered, critical or disordered based on their response to small perturbations. In the second study, random Boolean networks are taken as prototypical cases for the evaluation of two measures of complexity based on a criterion for optimal statistical prediction. One measure, defined for homogeneous systems, does not distinguish between the static spatial inhomogeneity in the ordered phase and the dynamical inhomogeneity in the disordered phase. A modification in which complexities of individual nodes are calculated yields vanishing

  12. The effects of autonomous and controlled regulation of performance-approach goals on well-being: a process model.

    PubMed

    Gillet, Nicolas; Lafrenière, Marc-André K; Vallerand, Robert J; Huart, Isabelle; Fouquereau, Evelyne

    2014-03-01

    The main purpose of the present research was to propose and test a motivational model linking achievement goal approach and self-determination theory. First, the effects of performance-approach goals and the autonomous and controlling reasons underlying their pursuit on well-being were investigated. Second, the mediating variables (i.e., effort, goal attainment, need satisfaction, and thwarting) at play in these relationships were examined based on the self-concordance model (Sheldon & Elliot, 1999). The model was tested in two studies in educational and work settings using cross sectional (Study 1) and prospective designs (Study 2). The present results revealed that considering autonomous and controlled regulations underlying performance-approach goals predicted well-being above and beyond the strength of performance-approach goals. Moreover, the mediational sequence based on the self-concordance model was supported in both studies. Theoretical implications and directions for future research are discussed. © 2012 The British Psychological Society.

  13. Modeling Forest Fire Occurrences Using Count-Data Mixed Models in Qiannan Autonomous Prefecture of Guizhou Province in China

    PubMed Central

    Ji, Ping

    2015-01-01

    Forest fires can cause catastrophic damage on natural resources. In the meantime, it can also bring serious economic and social impacts. Meteorological factors play a critical role in establishing conditions favorable for a forest fire. Effective prediction of forest fire occurrences could prevent or minimize losses. This paper uses count data models to analyze fire occurrence data which is likely to be dispersed and frequently contain an excess of zero counts (no fire occurrence). Such data have commonly been analyzed using count data models such as a Poisson model, negative binomial model (NB), zero-inflated models, and hurdle models. Data we used in this paper is collected from Qiannan autonomous prefecture of Guizhou province in China. Using the fire occurrence data from January to April (spring fire season) for the years 1996 through 2007, we introduced random effects to the count data models. In this study, the results indicated that the prediction achieved through NB model provided a more compelling and credible inferential basis for fitting actual forest fire occurrence, and mixed-effects model performed better than corresponding fixed-effects model in forest fire forecasting. Besides, among all meteorological factors, we found that relative humidity and wind speed is highly correlated with fire occurrence. PMID:25790309

  14. Modeling forest fire occurrences using count-data mixed models in Qiannan autonomous prefecture of Guizhou province in China.

    PubMed

    Xiao, Yundan; Zhang, Xiongqing; Ji, Ping

    2015-01-01

    Forest fires can cause catastrophic damage on natural resources. In the meantime, it can also bring serious economic and social impacts. Meteorological factors play a critical role in establishing conditions favorable for a forest fire. Effective prediction of forest fire occurrences could prevent or minimize losses. This paper uses count data models to analyze fire occurrence data which is likely to be dispersed and frequently contain an excess of zero counts (no fire occurrence). Such data have commonly been analyzed using count data models such as a Poisson model, negative binomial model (NB), zero-inflated models, and hurdle models. Data we used in this paper is collected from Qiannan autonomous prefecture of Guizhou province in China. Using the fire occurrence data from January to April (spring fire season) for the years 1996 through 2007, we introduced random effects to the count data models. In this study, the results indicated that the prediction achieved through NB model provided a more compelling and credible inferential basis for fitting actual forest fire occurrence, and mixed-effects model performed better than corresponding fixed-effects model in forest fire forecasting. Besides, among all meteorological factors, we found that relative humidity and wind speed is highly correlated with fire occurrence.

  15. The influence of underwater turbulence on optical phase measurements

    NASA Astrophysics Data System (ADS)

    Redding, Brandon; Davis, Allen; Kirkendall, Clay; Dandridge, Anthony

    2016-05-01

    Emerging underwater optical imaging and sensing applications rely on phase-sensitive detection to provide added functionality and improved sensitivity. However, underwater turbulence introduces spatio-temporal variations in the refractive index of water which can degrade the performance of these systems. Although the influence of turbulence on traditional, non-interferometric imaging has been investigated, its influence on the optical phase remains poorly understood. Nonetheless, a thorough understanding of the spatio-temporal dynamics of the optical phase of light passing through underwater turbulence are crucial to the design of phase-sensitive imaging and sensing systems. To address this concern, we combined underwater imaging with high speed holography to provide a calibrated characterization of the effects of turbulence on the optical phase. By measuring the modulation transfer function of an underwater imaging system, we were able to calibrate varying levels of optical turbulence intensity using the Simple Underwater Imaging Model (SUIM). We then used high speed holography to measure the temporal dynamics of the optical phase of light passing through varying levels of turbulence. Using this method, we measured the variance in the amplitude and phase of the beam, the temporal correlation of the optical phase, and recorded the turbulence induced phase noise as a function of frequency. By bench marking the effects of varying levels of turbulence on the optical phase, this work provides a basis to evaluate the real-world potential of emerging underwater interferometric sensing modalities.

  16. Measurements of optical underwater turbulence under controlled conditions

    NASA Astrophysics Data System (ADS)

    Kanaev, A. V.; Gladysz, S.; Almeida de Sá Barros, R.; Matt, S.; Nootz, G. A.; Josset, D. B.; Hou, W.

    2016-05-01

    Laser beam propagation underwater is becoming an important research topic because of high demand for its potential applications. Namely, ability to image underwater at long distances is highly desired for scientific and military purposes, including submarine awareness, diver visibility, and mine detection. Optical communication in the ocean can provide covert data transmission with much higher rates than that available with acoustic techniques, and it is now desired for certain military and scientific applications that involve sending large quantities of data. Unfortunately underwater environment presents serious challenges for propagation of laser beams. Even in clean ocean water, the extinction due to absorption and scattering theoretically limit the useful range to few attenuation lengths. However, extending the laser light propagation range to the theoretical limit leads to significant beam distortions due to optical underwater turbulence. Experiments show that the magnitude of the distortions that are caused by water temperature and salinity fluctuations can significantly exceed the magnitude of the beam distortions due to atmospheric turbulence even for relatively short propagation distances. We are presenting direct measurements of optical underwater turbulence in controlled conditions of laboratory water tank using two separate techniques involving wavefront sensor and LED array. These independent approaches will enable development of underwater turbulence power spectrum model based directly on the spatial domain measurements and will lead to accurate predictions of underwater beam propagation.

  17. Autonomous Reactor Control Using Model Based Predictive Control for Space Propulsion Applications

    SciTech Connect

    Bragg-Sitton, Shannon M.; Holloway, James Paul

    2005-02-06

    Reliable reactor control is important to reactor safety, both in terrestrial and space systems. For a space system, where the time for communication to Earth is significant, autonomous control is imperative. Based on feedback from reactor diagnostics, a controller must be able to automatically adjust to changes in reactor temperature and power level to maintain nominal operation without user intervention. Model-based predictive control (MBPC) (Clarke 1994; Morari 1994) is investigated as a potential control methodology for reactor start-up and transient operation in the presence of an external source. Bragg-Sitton and Holloway (2004) assessed the applicability of MBPC to reactor start-up from a cold, zero-power condition in the presence of a time-varying external radiation source, where large fluctuations in the external radiation source can significantly impact a reactor during start-up operations. The MBPC algorithm applied the point kinetics model to describe the reactor dynamics, using a single group of delayed neutrons; initial application considered a fast neutron lifetime (10-3 sec) to simplify calculations during initial controller analysis. The present study will more accurately specify the dynamics of a fast reactor, using a more appropriate fast neutron lifetime (10-7 sec) than in the previous work. Controller stability will also be assessed by carefully considering the dependencies of each component in the defined cost (objective) function and its subsequent effect on the selected 'optimal' control maneuvers.

  18. Methods for reducing interference in the Complementary Learning Systems model: oscillating inhibition and autonomous memory rehearsal.

    PubMed

    Norman, Kenneth A; Newman, Ehren L; Perotte, Adler J

    2005-11-01

    The stability-plasticity problem (i.e. how the brain incorporates new information into its model of the world, while at the same time preserving existing knowledge) has been at the forefront of computational memory research for several decades. In this paper, we critically evaluate how well the Complementary Learning Systems theory of hippocampo-cortical interactions addresses the stability-plasticity problem. We identify two major challenges for the model: Finding a learning algorithm for cortex and hippocampus that enacts selective strengthening of weak memories, and selective punishment of competing memories; and preventing catastrophic forgetting in the case of non-stationary environments (i.e. when items are temporarily removed from the training set). We then discuss potential solutions to these problems: First, we describe a recently developed learning algorithm that leverages neural oscillations to find weak parts of memories (so they can be strengthened) and strong competitors (so they can be punished), and we show how this algorithm outperforms other learning algorithms (CPCA Hebbian learning and Leabra at memorizing overlapping patterns. Second, we describe how autonomous re-activation of memories (separately in cortex and hippocampus) during REM sleep, coupled with the oscillating learning algorithm, can reduce the rate of forgetting of input patterns that are no longer present in the environment. We then present a simple demonstration of how this process can prevent catastrophic interference in an AB-AC learning paradigm.

  19. 3-D world modeling based on combinatorial geometry for autonomous robot navigation

    SciTech Connect

    Goldstein, M.; Pin, F.G.; de Saussure, G.; Weisbin, C.R.

    1987-01-01

    In applications of robotics to surveillance and mapping at nuclear facilities, the scene to be described is fundamentally three-dimensional. Usually, only partial information concerning the 3-D environment is known a-priori. Using an autonomous robot, this information may be updated using range data to provide an accurate model of the environment. Range data quantify the distances from the sensor focal plane to the object surface. In other words, the 3-D coordinates of discrete points on the object surface are known. The approach proposed herein for 3-D world modeling is based on the Combinatorial Geometry (C.G.) Method which is widely used in Monte Carlo particle transport calculations. First, each measured point on the object surface is surrounded by a small solid sphere with a radius determined by the range to that point. Then, the 3-D shapes of the visible surfaces are obtained by taking the (Boolean) union of all the spheres. The result is a concise and unambiguous representation of the object's boundary surfaces. The distances from discrete points on the robot's boundary surface to various objects are calculated effectively using the C.G. type of representation. This feature is particularly useful for navigation purposes. The efficiency of the proposed approach is illustrated by a simulation of a spherical robot navigating in a 3-D room with several static obstacles.

  20. Probabilistic Neighborhood-Based Data Collection Algorithms for 3D Underwater Acoustic Sensor Networks

    PubMed Central

    Han, Guangjie; Li, Shanshan; Zhu, Chunsheng; Jiang, Jinfang; Zhang, Wenbo

    2017-01-01

    Marine environmental monitoring provides crucial information and support for the exploitation, utilization, and protection of marine resources. With the rapid development of information technology, the development of three-dimensional underwater acoustic sensor networks (3D UASNs) provides a novel strategy to acquire marine environment information conveniently, efficiently and accurately. However, the specific propagation effects of acoustic communication channel lead to decreased successful information delivery probability with increased distance. Therefore, we investigate two probabilistic neighborhood-based data collection algorithms for 3D UASNs which are based on a probabilistic acoustic communication model instead of the traditional deterministic acoustic communication model. An autonomous underwater vehicle (AUV) is employed to traverse along the designed path to collect data from neighborhoods. For 3D UASNs without prior deployment knowledge, partitioning the network into grids can allow the AUV to visit the central location of each grid for data collection. For 3D UASNs in which the deployment knowledge is known in advance, the AUV only needs to visit several selected locations by constructing a minimum probabilistic neighborhood covering set to reduce data latency. Otherwise, by increasing the transmission rounds, our proposed algorithms can provide a tradeoff between data collection latency and information gain. These algorithms are compared with basic Nearest-neighbor Heuristic algorithm via simulations. Simulation analyses show that our proposed algorithms can efficiently reduce the average data collection completion time, corresponding to a decrease of data latency. PMID:28208735

  1. Probabilistic Neighborhood-Based Data Collection Algorithms for 3D Underwater Acoustic Sensor Networks.

    PubMed

    Han, Guangjie; Li, Shanshan; Zhu, Chunsheng; Jiang, Jinfang; Zhang, Wenbo

    2017-02-08

    Marine environmental monitoring provides crucial information and support for the exploitation, utilization, and protection of marine resources. With the rapid development of information technology, the development of three-dimensional underwater acoustic sensor networks (3D UASNs) provides a novel strategy to acquire marine environment information conveniently, efficiently and accurately. However, the specific propagation effects of acoustic communication channel lead to decreased successful information delivery probability with increased distance. Therefore, we investigate two probabilistic neighborhood-based data collection algorithms for 3D UASNs which are based on a probabilistic acoustic communication model instead of the traditional deterministic acoustic communication model. An autonomous underwater vehicle (AUV) is employed to traverse along the designed path to collect data from neighborhoods. For 3D UASNs without prior deployment knowledge, partitioning the network into grids can allow the AUV to visit the central location of each grid for data collection. For 3D UASNs in which the deployment knowledge is known in advance, the AUV only needs to visit several selected locations by constructing a minimum probabilistic neighborhood covering set to reduce data latency. Otherwise, by increasing the transmission rounds, our proposed algorithms can provide a tradeoff between data collection latency and information gain. These algorithms are compared with basic Nearest-neighbor Heuristic algorithm via simulations. Simulation analyses show that our proposed algorithms can efficiently reduce the average data collection completion time, corresponding to a decrease of data latency.

  2. Underwater welding, cutting and inspection

    SciTech Connect

    Tsai, C.L. . Ohio Underwater Welding Center)

    1995-02-01

    Underwater welding, cutting and inspection of offshore, inland waterway and port facilities are becoming a requirement for both military and industrial communities, as maintenance and repair costs continue to escalate, and as many of the facilities are in operation well beyond their intended design life. In nuclear applications, underwater welding, cutting and inspection for repair and modification of irradiated nuclear power plant components are also a requirement. This article summarizes recent developments in this emerging underwater technology.

  3. Perception of Work Load and Autonomic Responses: A Model for Student Experimentation.

    ERIC Educational Resources Information Center

    King, Elizabeth N.; Knight, Anne B.

    1980-01-01

    Described is an experiment that explores the relationships between conscious motor activity and autonomic processes such as breathing, blood pressure, and heart rate. Procedures for the construction and calibration of ball ergographs are outlined. (CS)

  4. Perception of Work Load and Autonomic Responses: A Model for Student Experimentation.

    ERIC Educational Resources Information Center

    King, Elizabeth N.; Knight, Anne B.

    1980-01-01

    Described is an experiment that explores the relationships between conscious motor activity and autonomic processes such as breathing, blood pressure, and heart rate. Procedures for the construction and calibration of ball ergographs are outlined. (CS)

  5. Natural Underwater Adhesives.

    PubMed

    Stewart, Russell J; Ransom, Todd C; Hlady, Vladimir

    2011-06-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)(3) coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  6. Conventional Weapons Underwater Explosions

    DTIC Science & Technology

    1988-12-01

    Bubble and a Solid Submerged Body, TRACOR Hydronautics Technical Report 86029-1 (1988). 26. Solomon, J., Szymczak , W., and Berger, A., private...FIELD GROUP SUB-GROUP Explosions, underwater, bubbles , detonatiohs, metal combustion, combustion 19 ABSTRACT (Continue on reverse if necessary and...detonations, bubble dynamics, bubble -water interface phencmena an~d metal combustion behavior, It was concluded that there are many potertial researCh areas

  7. NEW APPROACHES: Vision underwater

    NASA Astrophysics Data System (ADS)

    Steele, Alan L.

    1997-11-01

    A tutorial type problem examining the focusing performance of the human eye in air and in water is solved by two different approaches. Calculations show that light can be effectively focused on the retina when the eye is in air but not underwater, even with the usual accommodation. We then examine how some vertebrates have accommodation processes that permit them to see effectively both above and below water.

  8. Natural Underwater Adhesives

    PubMed Central

    Stewart, Russell J.; Ransom, Todd C.; Hlady, Vladimir

    2011-01-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  9. Exercise prevents development of autonomic dysregulation and hyperalgesia in a mouse model of chronic muscle pain.

    PubMed

    Sabharwal, Rasna; Rasmussen, Lynn; Sluka, Kathleen A; Chapleau, Mark W

    2016-02-01

    Chronic musculoskeletal pain (CMP) conditions, like fibromyalgia, are associated with widespread pain and alterations in autonomic functions. Regular physical activity prevents the development of CMP and can reduce autonomic dysfunction. We tested if there were alterations in autonomic function of sedentary mice with CMP, and whether exercise reduced the autonomic dysfunction and pain induced by CMP. Chronic musculoskeletal pain was induced by 2 intramuscular injections of pH 5.0 in combination with a single fatiguing exercise task. A running wheel was placed into cages so that the mouse had free access to it for either 5 days or 8 weeks (exercise groups) and these animals were compared to sedentary mice without running wheels. Autonomic function and nociceptive withdrawal thresholds of the paw and muscle were assessed before and after induction of CMP in exercised and sedentary mice. In sedentary mice, we show decreased baroreflex sensitivity, increased blood pressure variability, decreased heart rate variability, and decreased withdrawal thresholds of the paw and muscle 24 hours after induction of CMP. There were no sex differences after induction of the CMP in any outcome measure. We further show that both 5 days and 8 weeks of physical activity prevent the development of autonomic dysfunction and decreases in withdrawal threshold induced by CMP. Thus, this study uniquely shows the development of autonomic dysfunction in animals with chronic muscle hyperalgesia, which can be prevented with as little as 5 days of physical activity, and suggest that physical activity may prevent the development of pain and autonomic dysfunction in people with CMP.

  10. N(N)-nicotinic blockade as an acute human model of autonomic failure

    NASA Technical Reports Server (NTRS)

    Jordan, J.; Shannon, J. R.; Black, B. K.; Lance, R. H.; Squillante, M. D.; Costa, F.; Robertson, D.

    1998-01-01

    Pure autonomic failure has been conceptualized as deficient sympathetic and parasympathetic innervation. Several recent observations in chronic autonomic failure, however, cannot be explained simply by loss of autonomic innervation, at least according to our current understanding. To simulate acute autonomic failure, we blocked N(N)-nicotinic receptors with intravenous trimethaphan (6+/-0.4 mg/min) in 7 healthy subjects (4 men, 3 women, aged 32+/-3 years, 68+/-4 kg, 171+/-5 cm). N(N)-Nicotinic receptor blockade resulted in near-complete interruption of sympathetic and parasympathetic efferents as indicated by a battery of autonomic function tests. With trimethaphan, small postural changes from the horizontal were associated with significant blood pressure changes without compensatory changes in heart rate. Gastrointestinal motility, pupillary function, saliva production, and tearing were profoundly suppressed with trimethaphan. Plasma norepinephrine level decreased from 1.1+/-0.12 nmol/L (180+/-20 pg/mL) at baseline to 0.23+/-0.05 nmol/L (39+/-8 pg/mL) with trimethaphan (P<.001). There was a more than 16-fold increase in plasma vasopressin (P<.01) and no change in plasma renin activity. We conclude that blockade of N(N)-cholinergic receptors is useful to simulate the hemodynamic alterations of acute autonomic failure in humans. The loss of function with acute N(N)-cholinergic blockade is more complete than in most cases of chronic autonomic failure. This difference may be exploited to elucidate the contributions of acute denervation and chronic adaptation to the pathophysiology of autonomic failure. N(N)-Cholinergic blockade may also be applied to study human cardiovascular physiology and pharmacology in the absence of confounding baroreflexes.

  11. N(N)-nicotinic blockade as an acute human model of autonomic failure

    NASA Technical Reports Server (NTRS)

    Jordan, J.; Shannon, J. R.; Black, B. K.; Lance, R. H.; Squillante, M. D.; Costa, F.; Robertson, D.

    1998-01-01

    Pure autonomic failure has been conceptualized as deficient sympathetic and parasympathetic innervation. Several recent observations in chronic autonomic failure, however, cannot be explained simply by loss of autonomic innervation, at least according to our current understanding. To simulate acute autonomic failure, we blocked N(N)-nicotinic receptors with intravenous trimethaphan (6+/-0.4 mg/min) in 7 healthy subjects (4 men, 3 women, aged 32+/-3 years, 68+/-4 kg, 171+/-5 cm). N(N)-Nicotinic receptor blockade resulted in near-complete interruption of sympathetic and parasympathetic efferents as indicated by a battery of autonomic function tests. With trimethaphan, small postural changes from the horizontal were associated with significant blood pressure changes without compensatory changes in heart rate. Gastrointestinal motility, pupillary function, saliva production, and tearing were profoundly suppressed with trimethaphan. Plasma norepinephrine level decreased from 1.1+/-0.12 nmol/L (180+/-20 pg/mL) at baseline to 0.23+/-0.05 nmol/L (39+/-8 pg/mL) with trimethaphan (P<.001). There was a more than 16-fold increase in plasma vasopressin (P<.01) and no change in plasma renin activity. We conclude that blockade of N(N)-cholinergic receptors is useful to simulate the hemodynamic alterations of acute autonomic failure in humans. The loss of function with acute N(N)-cholinergic blockade is more complete than in most cases of chronic autonomic failure. This difference may be exploited to elucidate the contributions of acute denervation and chronic adaptation to the pathophysiology of autonomic failure. N(N)-Cholinergic blockade may also be applied to study human cardiovascular physiology and pharmacology in the absence of confounding baroreflexes.

  12. Autonomic neuropathies

    NASA Technical Reports Server (NTRS)

    Low, P. A.

    1998-01-01

    A limited autonomic neuropathy may underlie some unusual clinical syndromes, including the postural tachycardia syndrome, pseudo-obstruction syndrome, heat intolerance, and perhaps chronic fatigue syndrome. Antibodies to autonomic structures are common in diabetes, but their specificity is unknown. The presence of autonomic failure worsens prognosis in the diabetic state. Some autonomic neuropathies are treatable. Familial amyloid polyneuropathy may respond to liver transplantation. There are anecdotal reports of acute panautonomic neuropathy responding to intravenous gamma globulin. Orthostatic hypotension may respond to erythropoietin or midodrine.

  13. Autonomic neuropathies

    NASA Technical Reports Server (NTRS)

    Low, P. A.

    1998-01-01

    A limited autonomic neuropathy may underlie some unusual clinical syndromes, including the postural tachycardia syndrome, pseudo-obstruction syndrome, heat intolerance, and perhaps chronic fatigue syndrome. Antibodies to autonomic structures are common in diabetes, but their specificity is unknown. The presence of autonomic failure worsens prognosis in the diabetic state. Some autonomic neuropathies are treatable. Familial amyloid polyneuropathy may respond to liver transplantation. There are anecdotal reports of acute panautonomic neuropathy responding to intravenous gamma globulin. Orthostatic hypotension may respond to erythropoietin or midodrine.

  14. Recent Advances in Bathymetric Surveying of Continental Shelf Regions Using Autonomous Vehicles

    NASA Astrophysics Data System (ADS)

    Holland, K. T.; Calantoni, J.; Slocum, D.

    2016-02-01

    Obtaining bathymetric observations within the continental shelf in areas closer to the shore is often time consuming and dangerous, especially when uncharted shoals and rocks present safety concerns to survey ships and launches. However, surveys in these regions are critically important to numerical simulation of oceanographic processes, as bathymetry serves as the bottom boundary condition in operational forecasting models. We will present recent progress in bathymetric surveying using both traditional vessels retrofitted for autonomous operations and relatively inexpensive, small team deployable, Autonomous Underwater Vehicles (AUV). Both systems include either high-resolution multibeam echo sounders or interferometric sidescan sonar sensors with integrated inertial navigation system capabilities consistent with present commercial-grade survey operations. The advantages and limitations of these two configurations employing both unmanned and autonomous strategies are compared using results from several recent survey operations. We will demonstrate how sensor data collected from unmanned platforms can augment or even replace traditional data collection technologies. Oceanographic observations (e.g., sound speed, temperature and currents) collected simultaneously with bathymetry using autonomous technologies provide additional opportunities for advanced data assimilation in numerical forecasts. Discussion focuses on our vision for unmanned and autonomous systems working in conjunction with manned or in-situ systems to optimally and simultaneously collect data in environmentally hostile or difficult to reach areas.

  15. Underwater laser detection system

    NASA Astrophysics Data System (ADS)

    Gomaa, Walid; El-Sherif, Ashraf F.; El-Sharkawy, Yasser H.

    2015-02-01

    The conventional method used to detect an underwater target is by sending and receiving some form of acoustic energy. But the acoustic systems have limitations in the range resolution and accuracy; while, the potential benefits of a laserbased underwater target detection include high directionality, high response, and high range accuracy. Lasers operating in the blue-green region of the light spectrum(420 : 570nm)have a several applications in the area of detection and ranging of submersible targets due to minimum attenuation through water ( less than 0.1 m-1) and maximum laser reflection from estimated target (like mines or submarines) to provide a long range of detection. In this paper laser attenuation in water was measured experimentally by new simple method by using high resolution spectrometer. The laser echoes from different targets (metal, plastic, wood, and rubber) were detected using high resolution CCD camera; the position of detection camera was optimized to provide a high reflection laser from target and low backscattering noise from the water medium, digital image processing techniques were applied to detect and discriminate the echoes from the metal target and subtract the echoes from other objects. Extraction the image of target from the scattering noise is done by background subtraction and edge detection techniques. As a conclusion, we present a high response laser imaging system to detect and discriminate small size, like-mine underwater targets.

  16. Sensory and autonomic deficits in a new humanized mouse model of familial dysautonomia

    PubMed Central

    Morini, Elisabetta; Dietrich, Paula; Salani, Monica; Downs, Heather M.; Wojtkiewicz, Gregory R.; Alli, Shanta; Brenner, Anthony; Nilbratt, Mats; LeClair, John W.; Oaklander, Anne Louise; Slaugenhaupt, Susan A.; Dragatsis, Ioannis

    2016-01-01

    Familial dysautonomia (FD) is an autosomal recessive neurodegenerative disease that affects the development and survival of sensory and autonomic neurons. FD is caused by an mRNA splicing mutation in intron 20 of the IKBKAP gene that results in a tissue-specific skipping of exon 20 and a corresponding reduction of the inhibitor of kappaB kinase complex-associated protein (IKAP), also known as Elongator complex protein 1. To date, several promising therapeutic candidates for FD have been identified that target the underlying mRNA splicing defect, and increase functional IKAP protein. Despite these remarkable advances in drug discovery for FD, we lacked a phenotypic mouse model in which we could manipulate IKBKAP mRNA splicing to evaluate potential efficacy. We have, therefore, engineered a new mouse model that, for the first time, will permit to evaluate the phenotypic effects of splicing modulators and provide a crucial platform for preclinical testing of new therapies. This new mouse model, TgFD9; IkbkapΔ20/flox was created by introducing the complete human IKBKAP transgene with the major FD splice mutation (TgFD9) into a mouse that expresses extremely low levels of endogenous Ikbkap (IkbkapΔ20/flox). The TgFD9; IkbkapΔ20/flox mouse recapitulates many phenotypic features of the human disease, including reduced growth rate, reduced number of fungiform papillae, spinal abnormalities, and sensory and sympathetic impairments, and recreates the same tissue-specific mis-splicing defect seen in FD patients. This is the first mouse model that can be used to evaluate in vivo the therapeutic effect of increasing IKAP levels by correcting the underlying FD splicing defect. PMID:26769677

  17. Sensory and autonomic deficits in a new humanized mouse model of familial dysautonomia.

    PubMed

    Morini, Elisabetta; Dietrich, Paula; Salani, Monica; Downs, Heather M; Wojtkiewicz, Gregory R; Alli, Shanta; Brenner, Anthony; Nilbratt, Mats; LeClair, John W; Oaklander, Anne Louise; Slaugenhaupt, Susan A; Dragatsis, Ioannis

    2016-03-15

    Familial dysautonomia (FD) is an autosomal recessive neurodegenerative disease that affects the development and survival of sensory and autonomic neurons. FD is caused by an mRNA splicing mutation in intron 20 of the IKBKAP gene that results in a tissue-specific skipping of exon 20 and a corresponding reduction of the inhibitor of kappaB kinase complex-associated protein (IKAP), also known as Elongator complex protein 1. To date, several promising therapeutic candidates for FD have been identified that target the underlying mRNA splicing defect, and increase functional IKAP protein. Despite these remarkable advances in drug discovery for FD, we lacked a phenotypic mouse model in which we could manipulate IKBKAP mRNA splicing to evaluate potential efficacy. We have, therefore, engineered a new mouse model that, for the first time, will permit to evaluate the phenotypic effects of splicing modulators and provide a crucial platform for preclinical testing of new therapies. This new mouse model, TgFD9; Ikbkap(Δ20/flox) was created by introducing the complete human IKBKAP transgene with the major FD splice mutation (TgFD9) into a mouse that expresses extremely low levels of endogenous Ikbkap (Ikbkap(Δ20/flox)). The TgFD9; Ikbkap(Δ20/flox) mouse recapitulates many phenotypic features of the human disease, including reduced growth rate, reduced number of fungiform papillae, spinal abnormalities, and sensory and sympathetic impairments, and recreates the same tissue-specific mis-splicing defect seen in FD patients. This is the first mouse model that can be used to evaluate in vivo the therapeutic effect of increasing IKAP levels by correcting the underlying FD splicing defect. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Localization of non-linearly modeled autonomous mobile robots using out-of-sequence measurements.

    PubMed

    Besada-Portas, Eva; Lopez-Orozco, Jose A; Lanillos, Pablo; de la Cruz, Jesus M

    2012-01-01

    This paper presents a state of the art of the estimation algorithms dealing with Out-of-Sequence (OOS) measurements for non-linearly modeled systems. The state of the art includes a critical analysis of the algorithm properties that takes into account the applicability of these techniques to autonomous mobile robot navigation based on the fusion of the measurements provided, delayed and OOS, by multiple sensors. Besides, it shows a representative example of the use of one of the most computationally efficient approaches in the localization module of the control software of a real robot (which has non-linear dynamics, and linear and non-linear sensors) and compares its performance against other approaches. The simulated results obtained with the selected OOS algorithm shows the computational requirements that each sensor of the robot imposes to it. The real experiments show how the inclusion of the selected OOS algorithm in the control software lets the robot successfully navigate in spite of receiving many OOS measurements. Finally, the comparison highlights that not only is the selected OOS algorithm among the best performing ones of the comparison, but it also has the lowest computational and memory cost.

  19. Localization of Non-Linearly Modeled Autonomous Mobile Robots Using Out-of-Sequence Measurements

    PubMed Central

    Besada-Portas, Eva; Lopez-Orozco, Jose A.; Lanillos, Pablo; de la Cruz, Jesus M.

    2012-01-01

    This paper presents a state of the art of the estimation algorithms dealing with Out-of-Sequence (OOS) measurements for non-linearly modeled systems. The state of the art includes a critical analysis of the algorithm properties that takes into account the applicability of these techniques to autonomous mobile robot navigation based on the fusion of the measurements provided, delayed and OOS, by multiple sensors. Besides, it shows a representative example of the use of one of the most computationally efficient approaches in the localization module of the control software of a real robot (which has non-linear dynamics, and linear and non-linear sensors) and compares its performance against other approaches. The simulated results obtained with the selected OOS algorithm shows the computational requirements that each sensor of the robot imposes to it. The real experiments show how the inclusion of the selected OOS algorithm in the control software lets the robot successfully navigate in spite of receiving many OOS measurements. Finally, the comparison highlights that not only is the selected OOS algorithm among the best performing ones of the comparison, but it also has the lowest computational and memory cost. PMID:22736962

  20. Challenges in Modelling Hypoglycaemia-Associated Autonomic Failure: A Review of Human and Animal Studies

    PubMed Central

    Zhou, Xin-Fu

    2016-01-01

    Recurrent insulin-induced hypoglycaemia is a major limitation to insulin treatment in diabetes patients leading to a condition called hypoglycaemia-associated autonomic failure (HAAF). HAAF is characterised by reduced sympathoadrenal response to subsequent hypoglycaemia thereby predisposing the patients to severe hypoglycaemia that can lead to coma or even death. Despite several attempts being made, the mechanism of HAAF is yet to be clearly established. In order for the mechanism of HAAF to be elucidated, establishing a human/animal model of the phenomenon is the foremost requirement. Several research groups have attempted to reproduce the phenomenon in diabetic and nondiabetic humans and rodents and reported variable results. The success of the phenomenon is marked by a significant reduction in plasma adrenaline response to subsequent hypoglycaemic episode relative to that of the antecedent hypoglycaemic episode. A number of factors such as the insulin dosage, route of administration, fasting conditions, blood sampling methods and analyses, depth, duration, and number of antecedent hypoglycaemic episodes can impact the successful reproduction of the phenomenon and thus have to be carefully considered while developing the protocol. In this review, we have outlined the protocols followed by different research groups to reproduce the phenomenon in diabetic and nondiabetic humans and rodents including our own observations in rats and discussed the factors that have to be given careful consideration in reproducing the phenomenon successfully. PMID:27843452

  1. A study on model fidelity for model predictive control-based obstacle avoidance in high-speed autonomous ground vehicles

    NASA Astrophysics Data System (ADS)

    Liu, Jiechao; Jayakumar, Paramsothy; Stein, Jeffrey L.; Ersal, Tulga

    2016-11-01

    This paper investigates the level of model fidelity needed in order for a model predictive control (MPC)-based obstacle avoidance algorithm to be able to safely and quickly avoid obstacles even when the vehicle is close to its dynamic limits. The context of this work is large autonomous ground vehicles that manoeuvre at high speed within unknown, unstructured, flat environments and have significant vehicle dynamics-related constraints. Five different representations of vehicle dynamics models are considered: four variations of the two degrees-of-freedom (DoF) representation as lower fidelity models and a fourteen DoF representation with combined-slip Magic Formula tyre model as a higher fidelity model. It is concluded that the two DoF representation that accounts for tyre nonlinearities and longitudinal load transfer is necessary for the MPC-based obstacle avoidance algorithm in order to operate the vehicle at its limits within an environment that includes large obstacles. For less challenging environments, however, the two DoF representation with linear tyre model and constant axle loads is sufficient.

  2. Towards an Autonomous Space In-Situ Marine Sensorweb

    NASA Technical Reports Server (NTRS)

    Chien, S.; Doubleday, J.; Tran, D.; Thompson, D.; Mahoney, G.; Chao, Y.; Castano, R.; Ryan, J.; Kudela, R.; Palacios, S.; Foley, D.; Balasuriya, A.; Schmidt, H.; Schofield, O.; Arrott, M.; Meisinger, M.; Mandl, D.; Frye, S.; Ong, L.; Cappelaere, P.

    2009-01-01

    We describe ongoing efforts to integrate and coordinate space and marine assets to enable autonomous response to dynamic ocean phenomena such as algal blooms, eddies, and currents. Thus far we have focused on the use of remote sensing assets (e.g. satellites) but future plans include expansions to use a range of in-situ sensors such as gliders, autonomous underwater vehicles, and buoys/moorings.

  3. Machine Visual Guidance For An Autonomous Undersea Submersible

    NASA Astrophysics Data System (ADS)

    Nguyen, Hoa G.; Kaomea, Peter K.; Heckman, Paul J.

    1988-12-01

    Optical imaging is the preferred sensory modality for underwater robotic activities requiring high resolution at close range, such as station keeping, docking, control of manipulator, and object retrieval. Machine vision will play a vital part in the design of next generation autonomous underwater submersibles. This paper describes an effort to demonstrate that real-time vision-based guidance and control of autonomous underwater submersibles is possible with compact, low-power, and vehicle-imbeddable hardware. The Naval Ocean Systems Center's EAVE-WEST (Experimental Autonomous Vehicle-West) submersible is being used as the testbed. The vision hardware consists of a PC-bus video frame grabber and an IBM-PC/AT compatible single-board computer, both residing in the artificial intelligence/vision electronics bottle of the submersible. The specific application chosen involves the tracking of underwater buoy cables. Image recognition is performed in two steps. Feature points are identified in the underwater video images using a technique which detects one-dimensional local brightness minima and maxima. Hough transformation is then used to detect the straight line among these feature points. A hierarchical coarse-to-fine processing method is employed which terminates when enough feature points have been identified to allow a reliable fit. The location of the cable identified is then reported to the vehicle controller computer for automatic steering control. The process currently operates successfully with a throughput of approximately 2 frames per second.

  4. ANGIOTENSIN-DEPENDENT AUTONOMIC DYSREGULATION PRECEDES DILATED CARDIOMYOPATHY IN A MOUSE MODEL OF MUSCULAR DYSTROPHY

    PubMed Central

    Sabharwal, Rasna; Weiss, Robert M.; Zimmerman, Kathy; Domenig, Oliver; Cicha, Michael Z.; Chapleau, Mark W.

    2015-01-01

    Sarcoglycan mutations cause muscular dystrophy. Patients with muscular dystrophy develop autonomic dysregulation and dilated cardiomyopathy (DCM), but the temporal relationship and mechanism of autonomic dysregulation are not well understood. We hypothesized that activation of the renin-angiotensin system (RAS) causes autonomic dysregulation prior to development of DCM in sarcoglycan-delta (Sgcd) deficient mice, and that the severity of autonomic dysfunction at a young age predicts the severity of DCM at older ages. At 10-12 weeks of age, when left ventricular function assessed by echocardiography remained normal, Sgcd−/− mice exhibited decreases in arterial pressure, locomotor activity, baroreflex sensitivity (BRS) and cardiovagal tone, and increased sympathetic tone compared with age-matched C57BL/6 control mice (P<0.05). Systemic and skeletal muscle RAS were activated, and angiotensin II type 1 receptor (AT1R) expression, superoxide and fibrosis were increased in dystrophic skeletal muscle (P<0.05). Treatment with the AT1R blocker losartan for 7-9 weeks beginning at 3 weeks of age prevented or strongly attenuated the abnormalities in Sgcd−/− mice (P<0.05). Repeated assessment of phenotypes between 10 and 75 weeks of age demonstrated worsening of autonomic function, progressive cardiac dysfunction and DCM, and increased mortality in Sgcd−/− mice. High sympathetic tone predicted subsequent left ventricular dysfunction. We conclude that RAS activation causes severe autonomic dysregulation in young Sgcd−/− mice, which portends a worse long-term prognosis. Therapeutic targeting of RAS at a young age may improve autonomic function and slow disease progression in muscular dystrophy. PMID:25921929

  5. Brush development for underwater ship hull coating maintenance

    NASA Astrophysics Data System (ADS)

    Tribou, Melissa Eileen

    Ship hull grooming has been proposed as an environmentally friendly method of maintaining ship hull coatings in a fouling-free condition. It is defined as the frequent and gentle cleaning of a ship hull coating to prevent the establishment of fouling. This research investigated the grooming tool properties and operational requirements needed to implement the method. The grooming tool needs to provide sufficient force to remove incipient fouling without damaging the surface and consume minimal energy. Research showed that a vertical rotating brush design containing brushes filled with angled polypropylene bristles provided an effective method. This brush system was able to successfully prevent incipient fouling from becoming established on a copper ablative and two silicone fouling release coatings when groomed on a weekly basis; however, biofilm was not completely controlled. Brush design and operational parameters in relation to brush normal forces were investigated and models were developed to understand the relationship between bristle stiffness, dimensions, and angular velocity. A preliminary look at wear found that bristle stiffness has an effect on the degree of marring of the surface of a silicone fouling release coating. The knowledge gained by this research may be used to optimize grooming brush design and operational parameters that can be applied to the design and deployment of low power autonomous underwater vehicles that will groom the ship while in port.

  6. A flexible liquid crystal polymer MEMS pressure sensor array for fish-like underwater sensing

    NASA Astrophysics Data System (ADS)

    Kottapalli, A. G. P.; Asadnia, M.; Miao, J. M.; Barbastathis, G.; Triantafyllou, M. S.

    2012-11-01

    In order to perform underwater surveillance, autonomous underwater vehicles (AUVs) require flexible, light-weight, reliable and robust sensing systems that are capable of flow sensing and detecting underwater objects. Underwater animals like fish perform a similar task using an efficient and ubiquitous sensory system called a lateral-line constituting of an array of pressure-gradient sensors. We demonstrate here the development of arrays of polymer microelectromechanical systems (MEMS) pressure sensors which are flexible and can be readily mounted on curved surfaces of AUV bodies. An array of ten sensors with a footprint of 60 (L) mm × 25 (W) mm × 0.4 (H) mm is fabricated using liquid crystal polymer (LCP) as the sensing membrane material. The flow sensing and object detection capabilities of the array are illustrated with proof-of-concept experiments conducted in a water tunnel. The sensors demonstrate a pressure sensitivity of 14.3 μV Pa-1. A high resolution of 25 mm s-1 is achieved in water flow sensing. The sensors can passively sense underwater objects by transducing the pressure variations generated underwater by the movement of objects. The experimental results demonstrate the array’s ability to detect the velocity of underwater objects towed past by with high accuracy, and an average error of only 2.5%.

  7. Cell-autonomous progeroid changes in conditional mouse models for repair endonuclease XPG deficiency

    DOE PAGES

    Barnhoorn, Sander; Uittenboogaard, Lieneke M.; Jaarsma, Dick; ...

    2014-10-09

    As part of the Nucleotide Excision Repair (NER) process, the endonuclease XPG is involved in repair of helix-distorting DNA lesions, but the protein has also been implicated in several other DNA repair systems, complicating genotype-phenotype relationship in XPG patients. Defects in XPG can cause either the cancer-prone condition xeroderma pigmentosum (XP) alone, or XP combined with the severe neurodevelopmental disorder Cockayne Syndrome (CS), or the infantile lethal cerebro-oculo-facio-skeletal (COFS) syndrome, characterized by dramatic growth failure, progressive neurodevelopmental abnormalities and greatly reduced life expectancy. Here, we present a novel (conditional) Xpg-/- mouse model which—in a C57BL6/FVB F1 hybrid genetic background—displays manymore » progeroid features, including cessation of growth, loss of subcutaneous fat, kyphosis, osteoporosis, retinal photoreceptor loss, liver aging, extensive neurodegeneration, and a short lifespan of 4–5 months. We show that deletion of XPG specifically in the liver reproduces the progeroid features in the liver, yet abolishes the effect on growth or lifespan. In addition, specific XPG deletion in neurons and glia of the forebrain creates a progressive neurodegenerative phenotype that shows many characteristics of human XPG deficiency. Our findings therefore exclude that both the liver as well as the neurological phenotype are a secondary consequence of derailment in other cell types, organs or tissues (e.g. vascular abnormalities) and support a cell-autonomous origin caused by the DNA repair defect itself. In addition they allow the dissection of the complex aging process in tissue- and cell-type-specific components. Moreover, our data highlight the critical importance of genetic background in mouse aging studies, establish the Xpg-/- mouse as a valid model for the severe form of human XPG patients and segmental accelerated aging, and strengthen the link between DNA damage and aging.« less

  8. Cell-autonomous progeroid changes in conditional mouse models for repair endonuclease XPG deficiency

    SciTech Connect

    Barnhoorn, Sander; Uittenboogaard, Lieneke M.; Jaarsma, Dick; Vermeij, Wilbert P.; Tresini, Maria; Weymaere, Michael; Menoni, Hervé; Brandt, Renata M. C.; de Waard, Monique C.; Botter, Sander M.; Sarker, Altaf H.; Jaspers, Nicolaas G. J.; van der Horst, Gijsbertus T. J.; Cooper, Priscilla K.; Hoeijmakers, Jan H. J.; van der Pluijm, Ingrid; Niedernhofer, Laura J.

    2014-10-09

    As part of the Nucleotide Excision Repair (NER) process, the endonuclease XPG is involved in repair of helix-distorting DNA lesions, but the protein has also been implicated in several other DNA repair systems, complicating genotype-phenotype relationship in XPG patients. Defects in XPG can cause either the cancer-prone condition xeroderma pigmentosum (XP) alone, or XP combined with the severe neurodevelopmental disorder Cockayne Syndrome (CS), or the infantile lethal cerebro-oculo-facio-skeletal (COFS) syndrome, characterized by dramatic growth failure, progressive neurodevelopmental abnormalities and greatly reduced life expectancy. Here, we present a novel (conditional) Xpg-/- mouse model which—in a C57BL6/FVB F1 hybrid genetic background—displays many progeroid features, including cessation of growth, loss of subcutaneous fat, kyphosis, osteoporosis, retinal photoreceptor loss, liver aging, extensive neurodegeneration, and a short lifespan of 4–5 months. We show that deletion of XPG specifically in the liver reproduces the progeroid features in the liver, yet abolishes the effect on growth or lifespan. In addition, specific XPG deletion in neurons and glia of the forebrain creates a progressive neurodegenerative phenotype that shows many characteristics of human XPG deficiency. Our findings therefore exclude that both the liver as well as the neurological phenotype are a secondary consequence of derailment in other cell types, organs or tissues (e.g. vascular abnormalities) and support a cell-autonomous origin caused by the DNA repair defect itself. In addition they allow the dissection of the complex aging process in tissue- and cell-type-specific components. Moreover, our data highlight the critical importance of genetic background in mouse aging studies, establish the Xpg-/- mouse as a valid model for the severe form of human XPG patients and segmental accelerated aging, and strengthen the link between DNA damage and aging.

  9. Cell-Autonomous Progeroid Changes in Conditional Mouse Models for Repair Endonuclease XPG Deficiency

    PubMed Central

    Vermeij, Wilbert P.; Tresini, Maria; Weymaere, Michael; Menoni, Hervé; Brandt, Renata M. C.; de Waard, Monique C.; Botter, Sander M.; Sarker, Altaf H.; Jaspers, Nicolaas G. J.; van der Horst, Gijsbertus T. J.; Cooper, Priscilla K.; Hoeijmakers, Jan H. J.; van der Pluijm, Ingrid

    2014-01-01

    As part of the Nucleotide Excision Repair (NER) process, the endonuclease XPG is involved in repair of helix-distorting DNA lesions, but the protein has also been implicated in several other DNA repair systems, complicating genotype-phenotype relationship in XPG patients. Defects in XPG can cause either the cancer-prone condition xeroderma pigmentosum (XP) alone, or XP combined with the severe neurodevelopmental disorder Cockayne Syndrome (CS), or the infantile lethal cerebro-oculo-facio-skeletal (COFS) syndrome, characterized by dramatic growth failure, progressive neurodevelopmental abnormalities and greatly reduced life expectancy. Here, we present a novel (conditional) Xpg−/− mouse model which -in a C57BL6/FVB F1 hybrid genetic background- displays many progeroid features, including cessation of growth, loss of subcutaneous fat, kyphosis, osteoporosis, retinal photoreceptor loss, liver aging, extensive neurodegeneration, and a short lifespan of 4–5 months. We show that deletion of XPG specifically in the liver reproduces the progeroid features in the liver, yet abolishes the effect on growth or lifespan. In addition, specific XPG deletion in neurons and glia of the forebrain creates a progressive neurodegenerative phenotype that shows many characteristics of human XPG deficiency. Our findings therefore exclude that both the liver as well as the neurological phenotype are a secondary consequence of derailment in other cell types, organs or tissues (e.g. vascular abnormalities) and support a cell-autonomous origin caused by the DNA repair defect itself. In addition they allow the dissection of the complex aging process in tissue- and cell-type-specific components. Moreover, our data highlight the critical importance of genetic background in mouse aging studies, establish the Xpg−/− mouse as a valid model for the severe form of human XPG patients and segmental accelerated aging, and strengthen the link between DNA damage and aging. PMID:25299392

  10. Carbon Nanotube Underwater Acoustic Thermophone

    DTIC Science & Technology

    2016-09-23

    Attorney Docket No. 300009 1 of 8 A CARBON NANOTUBE UNDERWATER ACOUSTIC THERMOPHONE STATEMENT OF GOVERNMENT INTEREST [0001] The...the Invention [0003] The present invention is an acoustically transparent carbon nanotube thermophone. (2) Description of the Prior Art [0004...amplitude of the resulting sound waves. [0006] Recently, there has been development of underwater acoustic carbon nanotube (CNT) yarn sheets capable

  11. Design and implementation of an underwater sound recording device

    SciTech Connect

    Martinez, Jayson J.; Myers, Joshua R.; Carlson, Thomas J.; Deng, Zhiqun; Rohrer, John S.; Caviggia, Kurt A.; Woodley, Christa M.; Weiland, Mark A.

    2011-09-01

    To monitor the underwater sound and pressure waves generated by activities such as underwater blasting and pile driving, an autonomous system used to record underwater acoustic signals was designed. The device designed allows two hydrophones or other dynamic pressure sensors to be connected, filters out high frequency noise, has a gain that can be independently set for each sensor, and allows two hours of data to be collected. Two versions of the USR were created; one is submersible to a maximum depth of 300 m, and the other, although watertight, is not intended to be fully submersed. Tests were performed in the laboratory using a data acquisition system to send single-frequency sinusoidal voltages directly to the each component. These tests verified that the device performs as well as larger commercially available data acquisition systems, which are not suited for field use. A prototype of the device was used in a case study to investigate the effect of underwater rock blasting on juvenile Chinook salmon and rainbow trout. The case study demonstrated that the device was able to tolerate being operated in harsh environments, making it a valuable tool for collecting field measurements.

  12. ULTRA: Underwater Localization for Transit and Reconnaissance Autonomy

    NASA Technical Reports Server (NTRS)

    Huntsberger, Terrance L.

    2013-01-01

    This software addresses the issue of underwater localization of unmanned vehicles and the inherent drift in their onboard sensors. The software gives a 2 to 3 factor of improvement over the state-of-the-art underwater localization algorithms. The software determines the localization (position, heading) of an AUV (autonomous underwater vehicle) in environments where there is no GPS signal. It accomplishes this using only the commanded position, onboard gyros/accelerometers, and the bathymetry of the bottom provided by an onboard sonar system. The software does not rely on an onboard bathymetry dataset, but instead incrementally determines the position of the AUV while mapping the bottom. In order to enable long-distance underwater navigation by AUVs, a localization method called ULTRA uses registration of the bathymetry data products produced by the onboard forward-looking sonar system for hazard avoidance during a transit to derive the motion and pose of the AUV in order to correct the DR (dead reckoning) estimates. The registration algorithm uses iterative point matching (IPM) combined with surface interpolation of the Iterative Closest Point (ICP) algorithm. This method was used previously at JPL for onboard unmanned ground vehicle localization, and has been optimized for efficient computational and memory use.

  13. Effects of surface wettability on gecko adhesion underwater.

    PubMed

    Peng, Z L; Wang, C; Chen, S H

    2014-10-01

    Recent experiments have shown that gecko adhesion underwater depends significantly on surface wettability. Theoretical models of a gecko seta adhering on different substrates are firstly established in order to disclose such an adhesion mechanism. The results show that the capillary force induced by nano-bubbles between gecko seta and the substrate is the mainly influencing factor. The capillary force exhibits an attractive feature between gecko setae and hydrophobic surfaces underwater. However, it is extremely weak or even repulsive on hydrophilic surfaces underwater. A self-similarly splitting model is further considered to simulate multiple gecko setae on substrates underwater. It is interesting to find that the total capillary force depends significantly on the number of nano-bubble bridges and wettability of substrates. The total force is attractive and increases monotonically with the increase of the splitting number on hydrophobic substrates underwater. However, it decreases drastically or even becomes repulsive on hydrophilic substrates underwater. The present result can not only give a reasonable explanation on the existing experimental observations but also be helpful for the design of novel biomimetic adhesives.

  14. Autonomic neuropathies.

    PubMed

    Iodice, Valeria; Sandroni, Paola

    2014-10-01

    This article focuses on the most prevalent forms of autonomic neuropathies, but also discusses conditions such as focal and dysfunctional syndromes (altered autonomic function in the absence of structural lesions). The goal of this review is to allow the reader to promptly recognize these disorders, identify potentially reversible or treatable causes, and implement the appropriate treatment as well as supportive care. Secondary forms of autonomic neuropathies (eg, diabetes mellitus, amyloidosis) are much more common than primary forms, of which autoimmune ganglioneuropathies represent a major component. However, the spectrum of the latter is continuously evolving and has diagnostic and therapeutic implications. Testing modalities such as autonomic testing, serum autoimmune antibody testing, and skin biopsies are becoming more widely available. Autonomic neuropathies are relatively common conditions, and, because of the prognostic implications as well as impact on patient quality of life, they should be promptly recognized and treated aggressively. Testing is critical as other conditions may mimic autonomic neuropathies. Treatment is symptomatic in many cases, but specific therapies are also available in selected autonomic neuropathies.

  15. Underwater gas tornado

    NASA Astrophysics Data System (ADS)

    Byalko, Alexey V.

    2013-07-01

    We present the first experimental observation of a new hydrodynamic phenomenon, the underwater tornado. Simple measurements show that the tornado forms a vortex of the Rankine type, i.e. the rising gas rotates as a solid body and the liquid rotates with a velocity decreasing hyperbolically with the radius. We obtain the dependence of the tornado radius a on the gas stream value j theoretically: a ∼ j2/5. Processing of a set of experiments yielded the value 0.36 for the exponent in this expression. We also report the initial stages of the theoretical study of this phenomenon.

  16. Performance of Underwater Weldments

    DTIC Science & Technology

    1990-09-05

    background on the underwater wet and wet-backed SMAW process, including discussion of data gathered from the literature and from industry sources and...for wet-backed welds and HVN = 282 + 566(C.E.) for wet welds 18 TABLE 2.1. EFFECT OF WELDING VARIABLES ON HAZ HARDNESS A. SMAW Only, All Coatings...HARDNESS. 21 TABLE 2.2. EFFECT OF WELDING VARIABLES ON WELD METAL TENSILE STRENGTH A. SMAW Only, All Coatings --95 Observations (All were wet welds.) Range

  17. A Query Result Merging Scheme for Providing Energy Efficiency in Underwater Sensor Networks

    PubMed Central

    Kim, Yunsung; Park, Soo-Hyun

    2011-01-01

    Underwater sensor networks are emerging as a promising distributed data management system for various applications in underwater environments, despite their limited accessibility and restricted energy capacity. With the aid of recent developments in ubiquitous data computing, an increasing number of users are expected to overcome low accessibility by applying queries to underwater sensor networks. However, when multiple users send queries to an underwater sensor network in a disorganized manner, it may incur lethal energy waste and problematic network traffic. The current query management mechanisms cannot effectively deal with this matter due to their limited applicability and unrealistic assumptions. In this paper, a novel query management scheme involving query result merging is proposed for underwater sensor networks. The mechanism is based on a relational database model and is adjusted to the practical restrictions affecting underwater communication environments. Network simulations will prove that the scheme becomes more efficient with a greater number of queries and a smaller period range. PMID:22247695

  18. Evaluation of Underwater Welding and Cutting Equipment Available in 1969.

    DTIC Science & Technology

    UNDERWATER CUTTING, TORCHES), (*ARC WELDING , UNDERWATER EQUIPMENT), (*UNDERWATER EQUIPMENT, STATISTICAL DATA), SALVAGE, WELDABILITY, PERFORMANCE(ENGINEERING), PERFORMANCE(HUMAN), ANALYSIS OF VARIANCE.

  19. School Achievement and Backwardness Analysis Model at the Metropolitan Autonomous University--Cuajimalpa Unit

    ERIC Educational Resources Information Center

    Olivera-Villarroel, Sazcha Marcelo; del Pilar Fuerte-Celis, Maria

    2016-01-01

    This work stems from the need to develop a line of institutional policy recommendations to improve school performance and to reduce the backlog in the graduation of students in the Cuajimalpa Unit of the Metropolitan Autonomous University. The school backlog of students of this university is one of the main institutional concerns, due to the…

  20. Evidence for vestibular regulation of autonomic functions in a mouse genetic model

    NASA Technical Reports Server (NTRS)

    Murakami, Dean M.; Erkman, Linda; Hermanson, Ola; Rosenfeld, Michael G.; Fuller, Charles A.

    2002-01-01

    Physiological responses to changes in the gravitational field and body position, as well as symptoms of patients with anxiety-related disorders, have indicated an interrelationship between vestibular function and stress responses. However, the relative significance of cochlear and vestibular information in autonomic regulation remains unresolved because of the difficulties in distinguishing the relative contributions of other proprioceptive and interoceptive inputs, including vagal and somatic information. To investigate the role of cochlear and vestibular function in central and physiological responses, we have examined the effects of increased gravity in wild-type mice and mice lacking the POU homeodomain transcription factor Brn-3.1 (Brn-3bPou4f3). The only known phenotype of the Brn-3.1(-/-) mouse is related to hearing and balance functions, owing to the failure of cochlear and vestibular hair cells to differentiate properly. Here, we show that normal physiological responses to increased gravity (2G exposure), such as a dramatic drop in body temperature and concomitant circadian adjustment, were completely absent in Brn-3.1(-/-) mice. In line with the lack of autonomic responses, the massive increase in neuronal activity after 2G exposure normally detected in wild-type mice was virtually abolished in Brn-3.1(-/-) mice. Our results suggest that cochlear and vestibular hair cells are the primary regulators of autonomic responses to altered gravity and provide genetic evidence that these cells are sufficient to alter neural activity in regions involved in autonomic and neuroendocrine control.

  1. Evidence for vestibular regulation of autonomic functions in a mouse genetic model

    NASA Technical Reports Server (NTRS)

    Murakami, Dean M.; Erkman, Linda; Hermanson, Ola; Rosenfeld, Michael G.; Fuller, Charles A.

    2002-01-01

    Physiological responses to changes in the gravitational field and body position, as well as symptoms of patients with anxiety-related disorders, have indicated an interrelationship between vestibular function and stress responses. However, the relative significance of cochlear and vestibular information in autonomic regulation remains unresolved because of the difficulties in distinguishing the relative contributions of other proprioceptive and interoceptive inputs, including vagal and somatic information. To investigate the role of cochlear and vestibular function in central and physiological responses, we have examined the effects of increased gravity in wild-type mice and mice lacking the POU homeodomain transcription factor Brn-3.1 (Brn-3bPou4f3). The only known phenotype of the Brn-3.1(-/-) mouse is related to hearing and balance functions, owing to the failure of cochlear and vestibular hair cells to differentiate properly. Here, we show that normal physiological responses to increased gravity (2G exposure), such as a dramatic drop in body temperature and concomitant circadian adjustment, were completely absent in Brn-3.1(-/-) mice. In line with the lack of autonomic responses, the massive increase in neuronal activity after 2G exposure normally detected in wild-type mice was virtually abolished in Brn-3.1(-/-) mice. Our results suggest that cochlear and vestibular hair cells are the primary regulators of autonomic responses to altered gravity and provide genetic evidence that these cells are sufficient to alter neural activity in regions involved in autonomic and neuroendocrine control.

  2. Enhancing the Autonomous Use of CALL: A New Curriculum Model in EFL

    ERIC Educational Resources Information Center

    Smith, Karen; Craig, Hana

    2013-01-01

    This action research study evaluates the effectiveness of a CALL Learner Autonomy (CALL LA) course at a Japanese university. The "C course" blends face-to-face instruction and independent study in a CALL environment. It aims to enhance learners' autonomous use of CALL in the acquisition of English as a Foreign Language (EFL). In this…

  3. Enhancing the Autonomous Use of CALL: A New Curriculum Model in EFL

    ERIC Educational Resources Information Center

    Smith, Karen; Craig, Hana

    2013-01-01

    This action research study evaluates the effectiveness of a CALL Learner Autonomy (CALL LA) course at a Japanese university. The "C course" blends face-to-face instruction and independent study in a CALL environment. It aims to enhance learners' autonomous use of CALL in the acquisition of English as a Foreign Language (EFL). In this…

  4. Underwater laser scanning system

    NASA Astrophysics Data System (ADS)

    Austin, Roswell W.; Duntley, Seibert Q.; Ensminger, Richard L.; Petzold, Theodore J.; Smith, Raymond C.

    1991-12-01

    A system is described that produces high quality images through turbid waters by means of time encoded reflected light transmitted by scattering. The system consists of a compact battery operated laser scanning unit that scans the underwater scene with the laser beam in a manner similar to a television raster. Light reflected from any object in the scene varies in accordance with the reflectance of the minute spot being illuminated. This time varying intensity (TVI) signal is transmitted through the water to a remote receiver by both scattered and unscattered light where the received signal may be stored and/or displayed. The underwater laser scanning unit can be moved freely about the field of interest by scuba diver or ROV, unencumbered by entangling umbilicals, and can send real-time images over distances of 15 to 20 attenuation lengths to observers in a shirt-sleeve environment for critical viewing on an image display monitor. This previously undescribed system was developed in the early 1970s for proof of concept tests and used technology that is now 18 or more years old. The physical principles and the experimental hardware are described and examples are given of images providing exquisite detail that were made in an experimental tank together with some images obtained in ocean trials.

  5. Underwater Hearing in Turtles.

    PubMed

    Willis, Katie L

    2016-01-01

    The hearing of turtles is poorly understood compared with the other reptiles. Although the mechanism of transduction of sound into a neural signal via hair cells has been described in detail, the rest of the auditory system is largely a black box. What is known is that turtles have higher hearing thresholds than other reptiles, with best frequencies around 500 Hz. They also have lower underwater hearing thresholds than those in air, owing to resonance of the middle ear cavity. Further studies demonstrated that all families of turtles and tortoises share a common middle ear cavity morphology, with scaling best suited to underwater hearing. This supports an aquatic origin of the group. Because turtles hear best under water, it is important to examine their vulnerability to anthropogenic noise. However, the lack of basic data makes such experiments difficult because only a few species of turtles have published audiograms. There are also almost no behavioral data available (understandable due to training difficulties). Finally, few studies show what kinds of sounds are behaviorally relevant. One notable paper revealed that the Australian snake-necked turtle (Chelodina oblonga) has a vocal repertoire in air, at the interface, and under water. Findings like these suggest that there is more to the turtle aquatic auditory scene than previously thought.

  6. Loudness for tone underwater

    NASA Astrophysics Data System (ADS)

    Cudahy, Edward; Schwaller, Derek

    2002-05-01

    The loudness for pure tones was measured by loudness matching for 1-s pure tones from 100 to 50000 Hz. The standard tone was 1000 Hz. Subjects were instructed to match the loudness of the comparison tone at one of the test frequencies to the loudness of the standard tone. The standard was presented at one of five sound pressure levels (SPL) for each set of frequencies. The standard SPL was varied randomly across test series. The subjects were bareheaded US Navy divers tested at a depth of 3 m. All subjects had normal hearing. The tones were presented to the right side of the subject from an array of underwater sound projectors. The SPL was calibrated at the location of the subject's head with the subject absent. The loudness increased more rapidly as a function of standard SPL at mid-frequencies than at either high or low frequencies. The most compact loudness contours (least SPL change across range of standard SPL) were at 50000 Hz. The underwater loudness contours across frequency are significantly different from in-air measurements and have a minimum in the 1000 Hz region rather than the 2-4 kHz region observed for in-air measurements. [Work supported by ONR.

  7. Caenorhabditis elegans as a model system for studying non-cell-autonomous mechanisms in protein-misfolding diseases.

    PubMed

    Nussbaum-Krammer, Carmen I; Morimoto, Richard I

    2014-01-01

    Caenorhabditis elegans has a number of distinct advantages that are useful for understanding the basis for cellular and organismal dysfunction underlying age-associated diseases of protein misfolding. Although protein aggregation, a key feature of human neurodegenerative diseases, has been typically explored in vivo at the single-cell level using cells in culture, there is now increasing evidence that proteotoxicity has a non-cell-autonomous component and is communicated between cells and tissues in a multicellular organism. These discoveries have opened up new avenues for the use of C. elegans as an ideal animal model system to study non-cell-autonomous proteotoxicity, prion-like propagation of aggregation-prone proteins, and the organismal regulation of stress responses and proteostasis. This Review focuses on recent evidence that C. elegans has mechanisms to transmit certain classes of toxic proteins between tissues and a complex stress response that integrates and coordinates signals from single cells and tissues across the organism. These findings emphasize the potential of C. elegans to provide insights into non-cell-autonomous proteotoxic mechanisms underlying age-related protein-misfolding diseases.

  8. Channel analysis for single photon underwater free space quantum key distribution.

    PubMed

    Shi, Peng; Zhao, Shi-Cheng; Gu, Yong-Jian; Li, Wen-Dong

    2015-03-01

    We investigate the optical absorption and scattering properties of underwater media pertinent to our underwater free space quantum key distribution (QKD) channel model. With the vector radiative transfer theory and Monte Carlo method, we obtain the attenuation of photons, the fidelity of the scattered photons, the quantum bit error rate, and the sifted key generation rate of underwater quantum communication. It can be observed from our simulations that the most secure single photon underwater free space QKD is feasible in the clearest ocean water.

  9. A Study of 3-D Visualization and Knowledge-Based Mission Planning and Control for the NPS Model 2 Autonomous Underwater Vehicle

    DTIC Science & Technology

    1989-12-01

    if necessary and idenzify by block number Recently, specific tasking/total military mission concepts for subsea tasks have been developed that demand...military mission concepts for subsea tasks have been developed that demand substantially more endurance and range than can be provided by manned...to the recent past. During this era, almost all the required subsea tasks could be accomplished by manned submersibles (with their limited endurance

  10. DEPSCOR: Research on ARL’s Intelligent Control Architecture: Hierarchical Hybrid-Model Based Design, Verification, Simulation, and Synthesis of Mission Control for Autonomous Underwater Vehicles

    DTIC Science & Technology

    2007-02-01

    simulation tool can also be enhanced to get real time sensor information as feedback and then take actions accordingly. The simulation tool can be...indicates correct implementation) Change: TimeToWaypoint DistanceToWaypoint MinSpeed to check the various situations with the guard condition */ Efl ...guard condition */ Efl ] (WaypointNavigatorP. Time To Waypoint < WaypointNavigatorP.DistanceTo Waypoint / WaypointNavigatorP.MinSpeed) imply

  11. Active faults and seismogenic models for the Urumqi city, Xinjiang Autonomous Region, China

    NASA Astrophysics Data System (ADS)

    Li, Yingzhen; Yu, Yang; Shen, Jun; Shao, Bo; Qi, Gao; Deng, Mei

    2016-06-01

    We have studied the characteristics of the active faults and seismicity in the vicinity of Urumqi city, the capital of Xinjiang Autonomous Region, China, and have proposed a seismogenic model for the assessment of earthquake hazard in this area. Our work is based on an integrated analysis of data from investigations of active faults at the surface, deep seismic reflection soundings, seismic profiles from petroleum exploration, observations of temporal seismic stations, and the precise location of small earthquakes. We have made a comparative study of typical seismogenic structures in the frontal area of the North Tianshan Mountains, where Urumqi city is situated, and have revealed the primary features of the thrust-fold-nappe structure there. We suggest that Urumqi city is comprised two zones of seismotectonics which are interpreted as thrust-nappe structures. The first is the thrust nappe of the North Tianshan Mountains in the west, consisting of the lower (root) thrust fault, middle detachment, and upper fold-uplift at the front. Faults active in the Pleistocene are present in the lower and upper parts of this structure, and the detachment in the middle spreads toward the north. In the future, M7 earthquakes may occur at the root thrust fault, while the seismic risk of frontal fold-uplift at the front will not exceed M6.5. The second structure is the western flank of the arc-like Bogda nappe in the east, which is also comprised a root thrust fault, middle detachment, and upper fold-uplift at the front, of which the nappe stretches toward the north; several active faults are also developed in it. The fault active in the Holocene is called the South Fukang fault. It is not in the urban area of Urumqi city. The other three faults are located in the urban area and were active in the late Pleistocene. In these cases, this section of the nappe structure near the city has an earthquake risk of M6.5-7. An earthquake M S6.6, 60 km east to Urumqi city occurred along the

  12. Modeling of autonomous problem solving process by dynamic construction of task models in multiple tasks environment.

    PubMed

    Ohigashi, Yu; Omori, Takashi

    2006-10-01

    Traditional reinforcement learning (RL) supposes a complex but single task to be solved. When a RL agent faces a task similar to a learned one, the agent must re-learn the task from the beginning because it doesn't reuse the past learned results. This is the problem of quick action learning, which is the foundation of decision making in the real world. In this paper, we suppose agents that can solve a set of tasks similar to each other in a multiple tasks environment, where we encounter various problems one after another, and propose a technique of action learning that can quickly solve similar tasks by reusing previously learned knowledge. In our method, a model-based RL uses a task model constructed by combining primitive local predictors for predicting task and environmental dynamics. To evaluate the proposed method, we performed a computer simulation using a simple ping-pong game with variations.

  13. A non-cell autonomous mouse model of CNS haemangioblastoma mediated by mutant KRAS

    PubMed Central

    Bao, Leyuan; Al-Assar, Osama; Drynan, Lesley F.; Arends, Mark J.; Tyers, Pam; Barker, Roger A.; Rabbitts, Terence H.

    2017-01-01

    Haemangioblastoma is a rare malignancy of the CNS where vascular proliferation causes lesions due to endothelial propagation. We found that conditionally expressing mutant Kras, using Rag1-Cre, gave rise to CNS haemangioblastoma in the cortex and cerebellum in mice that present with highly vascular tumours with stromal cells similar to human haemangioblastomas. The aberrant haemangioblastoma endothelial cells do not express mutant Kras but rather the mutant oncogene is expressed in CNS interstitial cells, including neuronal cells and progeny. This demonstrates a non-cell autonomous origin of this disease that is unexpectedly induced via Rag1-Cre expression in CNS interstitial cells. This is the first time that mutant RAS has been shown to stimulate non-cell autonomous proliferation in malignancy and suggests that mutant RAS can control endothelial cell proliferation in neo-vascularisation when expressed in certain cells. PMID:28322325

  14. Evidence for vestibular regulation of autonomic functions in a mouse genetic model

    PubMed Central

    Murakami, Dean M.; Erkman, Linda; Hermanson, Ola; Rosenfeld, Michael G.; Fuller, Charles A.

    2002-01-01

    Physiological responses to changes in the gravitational field and body position, as well as symptoms of patients with anxiety-related disorders, have indicated an interrelationship between vestibular function and stress responses. However, the relative significance of cochlear and vestibular information in autonomic regulation remains unresolved because of the difficulties in distinguishing the relative contributions of other proprioceptive and interoceptive inputs, including vagal and somatic information. To investigate the role of cochlear and vestibular function in central and physiological responses, we have examined the effects of increased gravity in wild-type mice and mice lacking the POU homeodomain transcription factor Brn-3.1 (Brn-3b/Pou4f3). The only known phenotype of the Brn-3.1−/− mouse is related to hearing and balance functions, owing to the failure of cochlear and vestibular hair cells to differentiate properly. Here, we show that normal physiological responses to increased gravity (2G exposure), such as a dramatic drop in body temperature and concomitant circadian adjustment, were completely absent in Brn-3.1−/− mice. In line with the lack of autonomic responses, the massive increase in neuronal activity after 2G exposure normally detected in wild-type mice was virtually abolished in Brn-3.1−/− mice. Our results suggest that cochlear and vestibular hair cells are the primary regulators of autonomic responses to altered gravity and provide genetic evidence that these cells are sufficient to alter neural activity in regions involved in autonomic and neuroendocrine control. PMID:12466504

  15. Modelling and properties of a nonlinear autonomous switching system in fed-batch culture of glycerol

    NASA Astrophysics Data System (ADS)

    Wang, Juan; Sun, Qingying; Feng, Enmin

    2012-11-01

    A nonlinear autonomous switching system is proposed to describe the coupled fed-batch fermentation with the pH as the feedback parameter. We prove the non-Zeno behaviors of the switching system and some basic properties of its solution, including the existence, uniqueness, boundedness and regularity. Numerical simulation is also carried out, which reveals that the proposed system can describe the factual fermentation process properly.

  16. Toward Computational Modeling of C2 for Teams of Autonomous Systems and People

    DTIC Science & Technology

    2014-06-01

    Muller, J. 9/26/2012. With Driverless Cars , Once Again It Is California Leading The Way. Forbes; http://www.forbes.com/sites/joannmuller/2012/09/26...with- driverless - cars -once-again-it-is-california- leading-the-way/; retrieved 09/19/2013. Nissen, M.E. 2007. Computational Experimentation on New...map such degrees to the UAV domain. Briefly, in the autonomous automobile domain, Degree 0 corresponds to no autonomy; the car must be controlled

  17. Underwater wet welding of steel

    SciTech Connect

    Ibarra, S.; Liu, S.; Olson, D.L.

    1995-05-01

    Underwater wet welding is conducted directly in water with the shielded metal arc (SMA) and flux cored arc (FCA) welding processes. Underwater wet welding has been demonstrated as an acceptable repair technique down to 100 meters (325 ft.) in depth, but wet welds have been attempted on carbon steel structures down to 200 meters (650 ft.). The primary purpose of this interpretive report is to document and evaluate current understanding of metallurgical behavior of underwater wet welds so that new welding consumables can be designed and new welding practices can be developed for fabrication and repair of high strength steel structures at greater depths. First the pyrometallurgical and physical metallurgy behaviors of underwater weldments are discussed. Second, modifications of the welding consumables and processes are suggested to enhance the ability to apply wet welding techniques.

  18. Astronauts Practice Station Spacewalk Underwater

    NASA Image and Video Library

    Astronauts Robert Satcher Jr. and Rick Sturckow conduct an underwater practice spacewalk session at Johnson Space Center’s Neutral Buoyancy Laboratory. The session was used to help International Sp...

  19. Underwater boom box

    NASA Astrophysics Data System (ADS)

    White, M. Catherine

    So far, there is no evidence that humpback whales are negatively affected by noise emitted from underwater speakers that may one day be used to measure warming in the oceans. A group of independent biologists from Cornell University monitored the behavior of the whales before, during, and after a scaled-down version of the controversial Acoustic Thermometry of Ocean Climate (ATOC) experiment off the coast of Hawaii. In 84 trials from February through March, they “saw no overt response from the whales.” Previous observations of similar sound transmissions at California's Pioneer Seamount, the other site planned for the experiment, also found no sign of disturbance among marine mammals, including elephant seals and several whale species. More observations are needed, however, before the experiment can be deemed safe, the Cornell biologists advised.

  20. Architecture of autonomous systems

    NASA Technical Reports Server (NTRS)

    Dikshit, Piyush; Guimaraes, Katia; Ramamurthy, Maya; Agrawala, Ashok; Larsen, Ronald L.

    1989-01-01

    Automation of Space Station functions and activities, particularly those involving robotic capabilities with interactive or supervisory human control, is a complex, multi-disciplinary systems design problem. A wide variety of applications using autonomous control can be found in the literature, but none of them seem to address the problem in general. All of them are designed with a specific application in mind. In this report, an abstract model is described which unifies the key concepts underlying the design of automated systems such as those studied by the aerospace contractors. The model has been kept as general as possible. The attempt is to capture all the key components of autonomous systems. With a little effort, it should be possible to map the functions of any specific autonomous system application to the model presented here.