Laser Scanner Reliefs of Selected Archeological Structures in the Submerged Baiae (naples)

NASA Astrophysics Data System (ADS)

Davidde Petriaggi, B.; Gomez de Ayala, G.

2015-04-01

In 2011 the ISCR (Rome), in the frame of the Project Restoring Underwater directed by Barbara Davidde Petriaggi, started to test Naumacos Laser Scann 1, designed by Gabriele Gomez de Ayala, in order to document the restoration of a room paved with opus sectile probably part of the Bath of Punta Epitaffio (Underwater Park of Baiae - Marine Protected Area, Naples). The experimentation conducted in Baiae by ISCR has shown the effectiveness of the Laser Scanner; this method also allowed to considerably reduce times and costs of underwater surveying. Moreover, the 3D relief obtained, has the characteristic of being geometrically (accuracy is sub-millimetric) and chromatically faithful to the reconstructed structure, as well as being exportable in various forms and usable in several contexts. From 2011 to 2013 the evolution of the instrument Naumacos Laser Scanner 3 was developed and tested in the restoration work of the Villa con ingresso a protiro, where three structures were documented in 3D (a paved with black and white mosaic decorated with hexagons and peltae, a very fragmentary black and white mosaic and a stone artefact. This paper shows the results of this documentation campaign and it underlines the prominent role in documentation and in museum display of Underwater Cultural Heritage played by the three-dimensional laser scanning survey. This technique also contributes to the increase of the value of scientific dissemination.

Implantable acoustic-beacon automatic fish-tracking system

NASA Technical Reports Server (NTRS)

Mayhue, R. J.; Lovelady, R. W.; Ferguson, R. L.; Richards, C. E.

1977-01-01

A portable automatic fish tracking system was developed for monitoring the two dimensional movements of small fish within fixed areas of estuarine waters and lakes. By using the miniature pinger previously developed for this application, prototype tests of the system were conducted in the York River near the Virginia Institute of Marine Science with two underwater listening stations. Results from these tests showed that the tracking system could position the miniature pinger signals to within + or - 2.5 deg and + or - 135 m at ranges up to 2.5 km. The pingers were implanted in small fish and were successfully tracked at comparable ranges. No changes in either fish behavior or pinger performance were observed as a result of the implantation. Based on results from these prototype tests, it is concluded that the now commercially available system provides an effective approach to underwater tracking of small fish within a fixed area of interest.

EMI Modeling for UXO Detection and Discrimination Underwater

DTIC Science & Technology

2011-12-01

detection and discrimination underwater,? submitted to the Strategic Environmental Research and Development Program (SERDP) in response to the...phenomena from highly conducting and permeable metallic objects in underwater environments, and 3) investigate the impact of the electromagnetic parameters of...to the Department of Defense Strategic Environmental Research and Development Program (SERDP). The publication of this report does not indicate

New Polish occupational health and safety regulations for underwater works.

PubMed

Kot, Jacek; Sićko, Zdzisław

2007-01-01

In Poland, the new regulation of the Ministry of Health on Occupational Health for Underwater Works (dated 2007) pursuant to the Act on Underwater Works (dated 2003) has just been published. It is dedicated for commercial, non-military purposes. It defines health requirements for commercial divers and candidates for divers, medical assessment guide with a list of specific medical tests done on initial and periodical medical examination in order for a diver or a candidate for diver to be recognised fit for work, health surveillance during diving operations, compression and decompression procedures, list of content for medical equipment to be present at any diving place, formal qualifications for physicians conducting medical assessment of divers, requirements for certifications confirming the medical status of divers and candidates for divers. Decompression tables cover divings up to 120 meters of depth using compressed air, oxygen, nitrox and heliox as breathing mixtures. There are also decompression tables for repetitive diving, altitude diving and diving in the high-density waters (mud diving). It this paper, general description of health requirements for divers, as well as decompression tables that are included in the new Regulation on Occupational Health for Underwater Works are presented.

Underwater Electromagnetic Sensor Networks—Part I: Link Characterization †

PubMed Central

Quintana-Díaz, Gara; Mena-Rodríguez, Pablo; Pérez-Álvarez, Iván; Jiménez, Eugenio; Dorta-Naranjo, Blas-Pablo; Zazo, Santiago; Pérez, Marina; Quevedo, Eduardo; Cardona, Laura; Hernández, J. Joaquín

2017-01-01

Underwater Wireless Sensor Networks (UWSNs) using electromagnetic (EM) technology in marine shallow waters are examined, not just for environmental monitoring but for further interesting applications. Particularly, the use of EM waves is reconsidered in shallow waters due to the benefits offered in this context, where acoustic and optical technologies have serious disadvantages. Sea water scenario is a harsh environment for radiocommunications, and there is no standard model for the underwater EM channel. The high conductivity of sea water, the effect of seabed and the surface make the behaviour of the channel hard to predict. This justifies the need of link characterization as the first step to approach the development of EM underwater sensor networks. To obtain a reliable link model, measurements and simulations are required. The measuring setup for this purpose is explained and described, as well as the procedures used. Several antennas have been designed and tested in low frequency bands. Agreement between attenuation measurements and simulations at different distances was analysed and made possible the validation of simulation setups and the design of different communications layers of the system. This leads to the second step of this work, where data and routing protocols for the sensor network are examined. PMID:28106843

Underwater Electromagnetic Sensor Networks-Part I: Link Characterization.

PubMed

Quintana-Díaz, Gara; Mena-Rodríguez, Pablo; Pérez-Álvarez, Iván; Jiménez, Eugenio; Dorta-Naranjo, Blas-Pablo; Zazo, Santiago; Pérez, Marina; Quevedo, Eduardo; Cardona, Laura; Hernández, J Joaquín

2017-01-19

Underwater Wireless Sensor Networks (UWSNs) using electromagnetic (EM) technology in marine shallow waters are examined, not just for environmental monitoring but for further interesting applications. Particularly, the use of EM waves is reconsidered in shallow waters due to the benefits offered in this context, where acoustic and optical technologies have serious disadvantages. Sea water scenario is a harsh environment for radiocommunications, and there is no standard model for the underwater EM channel. The high conductivity of sea water, the effect of seabed and the surface make the behaviour of the channel hard to predict. This justifies the need of link characterization as the first step to approach the development of EM underwater sensor networks. To obtain a reliable link model, measurements and simulations are required. The measuring setup for this purpose is explained and described, as well as the procedures used. Several antennas have been designed and tested in low frequency bands. Agreement between attenuation measurements and simulations at different distances was analysed and made possible the validation of simulation setups and the design of different communications layers of the system. This leads to the second step of this work, where data and routing protocols for the sensor network are examined.

Determination of JWL Parameters for Non-Ideal Explosive

NASA Astrophysics Data System (ADS)

Hamashima, H.; Kato, Y.; Itoh, S.

2004-07-01

JWL equation of state is widely used in numerical simulation of detonation phenomena. JWL parameters are determined by cylinder test. Detonation characteristics of non-ideal explosive depend strongly on confinement, and JWL parameters determined by cylinder test do not represent the state of detonation products in many applications. We developed a method to determine JWL parameters from the underwater explosion test. JWL parameters were determined through a method of characteristics applied to the configuration of the underwater shock waves of cylindrical explosives. The numerical results obtained using JWL parameters determined by the underwater explosion test and those obtained using JWL parameters determined by cylinder test were compared with experimental results for typical non-ideal explosive; emulsion explosive. Good agreement was confirmed between the results obtained using JWL parameters determined by the underwater explosion test and experimental results.

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.

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

Using the combination refraction-reflection solid to design omni-directional light source used in underwater wireless optical communication

NASA Astrophysics Data System (ADS)

Rao, Jionghui; Yao, Wenming; Wen, Linqiang

2015-10-01

Underwater wireless optical communication is a communication technology which uses laser as an information carrier and transmits data through water. Underwater wireless optical communication has some good features such as broader bandwidth, high transmission rate, better security, anti—interference performance. Therefore, it is promising to be widely used in the civil and military communication domains. It is also suitable for high-speed, short-range communication between underwater mobile vehicles. This paper presents a design approach of omni-directional light source used in underwater wireless optical communication, using TRACEPRO simulation tool to help design a combination solid composed of the lens, conical reflector and parabolic reflector, and using the modulated DPSS green laser in the transmitter module to output the laser beam in small divergence angles, after expanded by the combination refraction-reflection solid, the angle turns into a space divergence angle of 2π, achieving the omni-directional light source of hemisphere space, and test in the air and underwater, the result shows that the effect is fine. This paper analyzes the experimental test in the air and water, in order to make further improvement of the uniformity of light distribution, we optimize the reflector surface parameters of combination refraction-reflection solid and test in the air and water. The result shows that omni-directional light source used in underwater wireless optical communication optimized could achieve the uniformity of light distribution of underwater space divergence angle of 2π. Omni-directional light source used in underwater wireless optical communication designed in this paper has the characteristics of small size and uniformity of light distribution, it is suitable for application between UUVs, AUVs, Swimmer Delivery Vehicles (SDVs) and other underwater vehicle fleet, it realizes point-to-multipoint communications.

29 CFR 1926.912 - Underwater blasting.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Underwater blasting. (a) A blaster shall conduct all blasting operations, and no shot shall be fired without... herein on handling and storing explosives. (h) When more than one charge is placed under water, a float...

29 CFR 1926.912 - Underwater blasting.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Underwater blasting. (a) A blaster shall conduct all blasting operations, and no shot shall be fired without... herein on handling and storing explosives. (h) When more than one charge is placed under water, a float...

29 CFR 1926.912 - Underwater blasting.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Underwater blasting. (a) A blaster shall conduct all blasting operations, and no shot shall be fired without... herein on handling and storing explosives. (h) When more than one charge is placed under water, a float...

29 CFR 1926.912 - Underwater blasting.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Underwater blasting. (a) A blaster shall conduct all blasting operations, and no shot shall be fired without... herein on handling and storing explosives. (h) When more than one charge is placed under water, a float...

29 CFR 1926.912 - Underwater blasting.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Underwater blasting. (a) A blaster shall conduct all blasting operations, and no shot shall be fired without... herein on handling and storing explosives. (h) When more than one charge is placed under water, a float...

Underwater manipulator's kinematic analysis for sustainable and energy efficient water hydraulics system

NASA Astrophysics Data System (ADS)

Hassan, Siti Nor Habibah; Yusof, Ahmad Anas; Tuan, Tee Boon; Saadun, Mohd Noor Asril; Ibrahim, Mohd Qadafie; Nik, Wan Mohd Norsani Wan

2015-05-01

In promoting energy saving and sustainability, this paper presents research development of water hydraulics manipulator test rig for underwater application. Kinematic analysis of the manipulator has been studied in order to identify the workspace of the fabricated manipulator. The workspace is important as it will define the working area suitable to be developed on the test rig, in order to study the effectiveness of using water hydraulics system for underwater manipulation application. Underwater manipulator that has the ability to utilize the surrounding sea water itself as the power and energy carrier should have better advantages over sustainability and performance.

A Summary of the Naval Postgraduate School Research Program.

DTIC Science & Technology

1982-05-01

and testing of PCM modu- lation formats, design and test of an underwater video line using a diver’s handheld camera and bi-directional interconnection...to design and develop advanced control schemes which successfully optimize the tor- pedo steering performance for Project Courageous. cummary: Work...investigating the feasibility and design of fiber optic communications in underwater torpedo ranges. Summary: An underwater fiber optic video uplink was

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

DTIC Science & Technology

2013-09-30

underwater acoustic communication technologies for autonomous distributed underwater networks, through innovative signal processing, coding, and navigation...in real enviroments , an offshore testbed has been developed to conduct field experimetns. The testbed consists of four nodes and has been deployed...Leadership by the Connecticut Technology Council. Dr. Zhaohui Wang joined the faculty of the Department of Electrical and Computer Engineering at

Visual training improves underwater vision in children.

PubMed

Gislén, Anna; Warrant, Eric J; Dacke, Marie; Kröger, Ronald H H

2006-10-01

Children in a tribe of sea-gypsies from South-East Asia have been found to have superior underwater vision compared to European children. In this study, we show that the improved underwater vision of these Moken children is not due to better contrast sensitivity in general. We also show that European children can achieve the same underwater acuity as the Moken children. After 1 month of underwater training (11 sessions) followed by 4 months with no underwater activities, European children showed improved underwater vision and distinct bursts of pupil constriction. When tested 8 months after the last training session in an outdoor pool in bright sunlight-comparable to light environments in South-East Asia-the children had attained the same underwater acuity as the sea-gypsy children. The achieved performance can be explained by the combined effect of pupil constriction and strong accommodation.

75 FR 79342 - Taking and Importing Marine Mammals; Navy Training Activities Conducted Within the Northwest...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-20

...-frequency or high frequency active sonar (MFAS/HFAS) or to underwater detonations at levels that NMFS... exposing them to sound from mid-frequency or high frequency active sonar (MFAS/HFAS) or underwater...

Experimental Investigations of the Effects of Underwater Explosions on Swimbladder Fish. I. 1973 Chesapeake Bay Tests

DTIC Science & Technology

1975-06-20

H1101600 Underwater Explosions Explosion Effects on Fish Fish Lethal Ranges " Environmental Effects of Explosions 𔃺. A*STRACT reverse side It nooosemy and...effects of its research operations. When such operations involve the detonation of underwater explosions, one of the environmental factors to be evaluated...04o APPENDIX A: EXPERIMENTS WITH CRABS AND OYSTERS ......... .. A-I APPENDIX B: FINAL REPORT: ENVIRONMENTAL EFFECTS OF EXPLOSIVE TESTING

a Comparison Between Active and Passive Techniques for Underwater 3d Applications

NASA Astrophysics Data System (ADS)

Bianco, G.; Gallo, A.; Bruno, F.; Muzzupappa, M.

2011-09-01

In the field of 3D scanning, there is an increasing need for more accurate technologies to acquire 3D models of close range objects. Underwater exploration, for example, is very hard to perform due to the hostile conditions and the bad visibility of the environment. Some application fields, like underwater archaeology, require to recover tridimensional data of objects that cannot be moved from their site or touched in order to avoid possible damages. Photogrammetry is widely used for underwater 3D acquisition, because it requires just one or two digital still or video cameras to acquire a sequence of images taken from different viewpoints. Stereo systems composed by a pair of cameras are often employed on underwater robots (i.e. ROVs, Remotely Operated Vehicles) and used by scuba divers, in order to survey archaeological sites, reconstruct complex 3D structures in aquatic environment, estimate in situ the length of marine organisms, etc. The stereo 3D reconstruction is based on the triangulation of corresponding points on the two views. This requires to find in both images common points and to match them (correspondence problem), determining a plane that contains the 3D point on the object. Another 3D technique, frequently used in air acquisition, solves this point-matching problem by projecting structured lighting patterns to codify the acquired scene. The corresponding points are identified associating a binary code in both images. In this work we have tested and compared two whole-field 3D imaging techniques (active and passive) based on stereo vision, in underwater environment. A 3D system has been designed, composed by a digital projector and two still cameras mounted in waterproof housing, so that it can perform the various acquisitions without changing the configuration of optical devices. The tests were conducted in a water tank in different turbidity conditions, on objects with different surface properties. In order to simulate a typical seafloor, we used various concentrations of clay. The performances of the two techniques are described and discussed. In particular, the point clouds obtained are compared in terms of number of acquired 3D points and geometrical deviation.

The Theseus Autonomous Underwater Vehicle: A Canadian Success Story

DTIC Science & Technology

1997-04-01

P502414.PDF [Page: 1 of 9] P502414.PDF [Page: 2 of 9] P502414.PDF [Page: 3 of 9] The Theseus Autonomous Underwater Vehicle A Canadian Success Story...autonomous underwater vehicle, named Theseus , for laying optical fiber cables in ice- covered waters. In trials and missions conducted in 1996, this...stations. An acoustic telemetry system enables communication with Theseus from surface stations, and an optical telemetry system is used for system

Actuated Recoil Absorbing Mounting System for use with an Underwater Gun

DTIC Science & Technology

1998-03-31

fire supercavitating bullets, requires that 20 the new projectile launchers be tested. The firing of projectile 21 launchers involving a high...of projectile launcher 12 includes an underwater gun 15 that fires supercavitating bullets underwater and has a high 16 discharge energy. However

Underwater laser weld bowing distortion behavior and mechanism of thin 304 stainless steel plates

NASA Astrophysics Data System (ADS)

Huang, ZunYue; Luo, Zhen; Ao, Sansan; Cai, YangChuan

2018-10-01

Underwater laser weld bowing distortion behavior and mechanism of thin 304 stainless steel plates are studied in the paper. The influence of underwater laser welding parameters (such as laser power, welding speed, defocusing distance and gas flow rate) on weld bowing distortion was investigated through central composite rotatable design and an orthogonal test. A quadratic response model was established to evaluate the underwater laser weld bowing distortion by central composite rotatable design and the order of the impacts of the welding parameters on weld bowing distortion was studied by an orthogonal test. The weld bowing distortion after welding was determined by the digital image correlation technique. The weld bowing distortion of in-air laser welding and underwater laser welding were compared and it revealed that the shape of the in-air and underwater laser welded specimens are the same, but the weld bowing distortion amount of in-air welding is larger than that of underwater welding. Weld bowing distortion mechanism was studied by the digital image correlation technique, and it was demonstrated that weld bowing distortion is associated with the welding plate temperature gradient during laser welding. The wider weld width also resulted in larger weld bowing distortion.

KENNEDY SPACE CENTER, FLA. - Researchers conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Researchers conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

Trajectory-based visual localization in underwater surveying missions.

PubMed

Burguera, Antoni; Bonin-Font, Francisco; Oliver, Gabriel

2015-01-14

We present a new vision-based localization system applied to an autonomous underwater vehicle (AUV) with limited sensing and computation capabilities. The traditional EKF-SLAM approaches are usually expensive in terms of execution time; the approach presented in this paper strengthens this method by adopting a trajectory-based schema that reduces the computational requirements. The pose of the vehicle is estimated using an extended Kalman filter (EKF), which predicts the vehicle motion by means of a visual odometer and corrects these predictions using the data associations (loop closures) between the current frame and the previous ones. One of the most important steps in this procedure is the image registration method, as it reinforces the data association and, thus, makes it possible to close loops reliably. Since the use of standard EKFs entail linearization errors that can distort the vehicle pose estimations, the approach has also been tested using an iterated Kalman filter (IEKF). Experiments have been conducted using a real underwater vehicle in controlled scenarios and in shallow sea waters, showing an excellent performance with very small errors, both in the vehicle pose and in the overall trajectory estimates.

Another round for noisy ocean temperature test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, C.

1993-03-05

It's a deal a talk show host would kill for: $35 million to sound off for a while. But there's one other aspect of the bargain that might be a bit tough for the average radio personality: You've got to listen to your own noise and gauge whether the world is warming. Luckily, that's nothing new for oceanographer Walter Munk, who last week won funding from the Defense Advanced Research Projects Agency to conduct a second trial of his underwater sonic thermometer of the world's oceans. Sound waves are pulsed form underwater loudspeakers to receivers thousands of miles away. Bymore » the measuring the elapsed time, Munk and his collaborators can precisely measure temperatures in entire ocean basins and watch for signs of global warming.« less

Evaluation of electrical conductivity and equations of state of non-ideal plasma through microsecond timescale underwater electrical wire explosion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheftman, D.; Krasik, Ya. E.

2011-09-15

Experimental and simulation results of underwater electrical Cu, Al, and W wire explosions in the microsecond timescale are presented. It was shown that the electrical conductivity results for Cu and Al agree well with modified Lee-More and quantum molecular dynamic models for temperatures above 10 kK. The equation of state (EOS) values based on SESAME tables for Cu and Al were slightly modified for intermediate temperatures in order to obtain fitting between experimental and simulated exploding wire radial expansion. Also, it was shown that the electrical conductivity results and the EOS evaluation differ significantly from the results obtained in nanosecondmore » timescale experiments. Finally, it was found that underwater electrical W wire explosion is characterized by the appearance of non-uniformities along the z-axis of the wire. This phenomena adds uncertainty to the possibility of applying this type of experiments for evaluation of the electrical conductivity and EOS of W.« less

Underwater Photo-Elicitation: A New Experiential Marine Education Technique

ERIC Educational Resources Information Center

Andrews, Steve; Stocker, Laura; Oechel, Walter

2018-01-01

Underwater photo-elicitation is a novel experiential marine education technique that combines direct experience in the marine environment with the use of digital underwater cameras. A program called Show Us Your Ocean! (SUYO!) was created, utilising a mixed methodology (qualitative and quantitative methods) to test the efficacy of this technique.…

The effect of different rutile electrodes on mechanical properties of underwater wet welded AH-36 steel plates

NASA Astrophysics Data System (ADS)

Winarto, Winarto; Purnama, Dewin; Churniawan, Iwan

2018-04-01

Underwater welding is an important role in the rescue of ships and underwater structures, in case of emergency. In this study, the marine steel plates used are AH-36 steel as parent material. This type of steel is included in the High Strength Low Alloy (HSLA). Electrodes used for welding AH-36 steel plates are commonly the E6013 and E 7024 which are the type of based rutile electrodes. Those electrodes are widely available on the market and they would be compared with the original electrode for underwater which is the type of E7014 with the trade name of Broco UW-CS-1. Welding method used is Shielding Metal Arc Welding (SMAW) with the variation of 5 m and 10 m underwater depth and also varied with the electric current of 120A, 140A and 250A. It was found that hardness value of increased in the area of weld metal and HAZ. HAZ also tends to have the highest hardness compared to both of weld metal and base metal. Non destructive test by radiographed test (RT) on welds showed that there are found welding defects in the form of incomplete penetration on all variations of welding parameters, but there is no porosity defect detected. The results of the hardness tests of underwater wet welded steel plates show that the hardness value of both rutile electrodes (E6013 and E 7024) is apparently similar hardness value compared with the existing commercial electrode (E7014 of Broco UW-CS- 1). The tensile test results of underwater wet welded steel plates show that the use of rutile electrode of E6013 gives a better tensile properties than other rutile electrodes.

Application of a high-energy-density permanent magnet material in underwater systems

NASA Astrophysics Data System (ADS)

Cho, C. P.; Egan, C.; Krol, W. P.

1996-06-01

This paper addresses the application of high-energy-density permanent magnet (PM) technology to (1) the brushless, axial-field PM motor and (2) the integrated electric motor/pump system for under-water applications. Finite-element analysis and lumped parameter magnetic circuit analysis were used to calculate motor parameters and performance characteristics and to conduct tradeoff studies. Compact, efficient, reliable, and quiet underwater systems are attainable with the development of high-energy-density PM material, power electronic devices, and power integrated-circuit technology.

Underwater localization of pure tones by harbor seals (Phoca vitulina).

PubMed

Bodson, Anaïs; Miersch, Lars; Dehnhardt, Guido

2007-10-01

The underwater sound localization acuity of harbor seals (Phoca vitulina) was measured in the horizontal plane. Minimum audible angles (MAAs) of pure tones were determined as a function of frequency from 0.2 to 16 kHz for two seals. Testing was conducted in a 10-m-diam underwater half circle using a right/left psychophysical procedure. The results indicate that for both harbor seals, MAAs were large at high frequencies (13.5 degrees and 17.4 degrees at 16 kHz), transitional at intermediate frequencies (9.6 degrees and 10.1 degrees at 4 kHz), and particularly small at low frequencies (3.2 degrees and 3.1 degrees at 0.2 kHz). Harbor seals seem to be able to utilize both binaural cues, interaural time differences (ITDs) and interaural intensity differences (IIDs), but a significant decrease in the sound localization acuity with increasing frequency suggests that IID cues may not be as robust as ITD cues under water. These results suggest that the harbor seal can be regarded as a low-frequency specialist. Additionally, to obtain a MAA more representative of the species, the horizontal underwater MAA of six adult harbor seals was measured at 2 kHz under identical conditions. The MAAs of the six animals ranged from 8.8 degrees to 11.7 degrees , resulting in a mean MAA of 10.3 degrees .

Mars aerobrake assembly simulation

NASA Technical Reports Server (NTRS)

Filatovs, G. J.; Lee, Gordon K. F.; Garvey, John

1992-01-01

On-orbit assembly operation simulations in neutral buoyancy conditions are presently undertaken by a partial/full-scale Mars mission aerobrake mockup, whose design, conducted in the framework of an engineering senior students' design project, involved several levels of constraints for critical physical and operational features. Allowances had to be made for the auxiliary constraints introduced by underwater testing, as well as the subsegmenting required for overland shipment to the neutral-buoyancy testing facility. This mockup aerobrake's fidelity is determined by the numerous, competing design objectives.

RF Path and Absorption Loss Estimation for Underwater Wireless Sensor Networks in Different Water Environments

PubMed Central

Qureshi, Umair Mujtaba; Shaikh, Faisal Karim; Aziz, Zuneera; Shah, Syed M. Zafi S.; Sheikh, Adil A.; Felemban, Emad; Qaisar, Saad Bin

2016-01-01

Underwater Wireless Sensor Network (UWSN) communication at high frequencies is extremely challenging. The intricacies presented by the underwater environment are far more compared to the terrestrial environment. The prime reason for such intricacies are the physical characteristics of the underwater environment that have a big impact on electromagnetic (EM) signals. Acoustics signals are by far the most preferred choice for underwater wireless communication. Because high frequency signals have the luxury of large bandwidth (BW) at shorter distances, high frequency EM signals cannot penetrate and propagate deep in underwater environments. The EM properties of water tend to resist their propagation and cause severe attenuation. Accordingly, there are two questions that need to be addressed for underwater environment, first what happens when high frequency EM signals operating at 2.4 GHz are used for communication, and second which factors affect the most to high frequency EM signals. To answer these questions, we present real-time experiments conducted at 2.4 GHz in terrestrial and underwater (fresh water) environments. The obtained results helped in studying the physical characteristics (i.e., EM properties, propagation and absorption loss) of underwater environments. It is observed that high frequency EM signals can propagate in fresh water at a shallow depth only and can be considered for a specific class of applications such as water sports. Furthermore, path loss, velocity of propagation, absorption loss and the rate of signal loss in different underwater environments are also calculated and presented in order to understand why EM signals cannot propagate in sea water and oceanic water environments. An optimal solk6ution for underwater communication in terms of coverage distance, bandwidth and nature of communication is presented, along with possible underwater applications of UWSNs at 2.4 GHz. PMID:27322263

RF Path and Absorption Loss Estimation for Underwater Wireless Sensor Networks in Different Water Environments.

PubMed

Qureshi, Umair Mujtaba; Shaikh, Faisal Karim; Aziz, Zuneera; Shah, Syed M Zafi S; Sheikh, Adil A; Felemban, Emad; Qaisar, Saad Bin

2016-06-16

Underwater Wireless Sensor Network (UWSN) communication at high frequencies is extremely challenging. The intricacies presented by the underwater environment are far more compared to the terrestrial environment. The prime reason for such intricacies are the physical characteristics of the underwater environment that have a big impact on electromagnetic (EM) signals. Acoustics signals are by far the most preferred choice for underwater wireless communication. Because high frequency signals have the luxury of large bandwidth (BW) at shorter distances, high frequency EM signals cannot penetrate and propagate deep in underwater environments. The EM properties of water tend to resist their propagation and cause severe attenuation. Accordingly, there are two questions that need to be addressed for underwater environment, first what happens when high frequency EM signals operating at 2.4 GHz are used for communication, and second which factors affect the most to high frequency EM signals. To answer these questions, we present real-time experiments conducted at 2.4 GHz in terrestrial and underwater (fresh water) environments. The obtained results helped in studying the physical characteristics (i.e., EM properties, propagation and absorption loss) of underwater environments. It is observed that high frequency EM signals can propagate in fresh water at a shallow depth only and can be considered for a specific class of applications such as water sports. Furthermore, path loss, velocity of propagation, absorption loss and the rate of signal loss in different underwater environments are also calculated and presented in order to understand why EM signals cannot propagate in sea water and oceanic water environments. An optimal solk6ution for underwater communication in terms of coverage distance, bandwidth and nature of communication is presented, along with possible underwater applications of UWSNs at 2.4 GHz.

Optimized decoy state QKD for underwater free space communication

NASA Astrophysics Data System (ADS)

Lopes, Minal; Sarwade, Nisha

Quantum cryptography (QC) is envisioned as a solution for global key distribution through fiber optic, free space and underwater optical communication due to its unconditional security. In view of this, this paper investigates underwater free space quantum key distribution (QKD) model for enhanced transmission distance, secret key rates and security. It is reported that secure underwater free space QKD is feasible in the clearest ocean water with the sifted key rates up to 207kbps. This paper extends this work by testing performance of optimized decoy state QKD protocol with underwater free space communication model. The attenuation of photons, quantum bit error rate and the sifted key generation rate of underwater quantum communication is obtained with vector radiative transfer theory and Monte Carlo method. It is observed from the simulations that optimized decoy state QKD evidently enhances the underwater secret key transmission distance as well as secret key rates.

A New Method for Determining the Equation of State of Aluminized Explosive

NASA Astrophysics Data System (ADS)

Zhou, Zheng-Qing; Nie, Jian-Xin; Guo, Xue-Yong; Wang, Qiu-Shi; Ou, Zhuo-Cheng; Jiao, Qing-Jie

2015-01-01

The time-dependent Jones—Wilkins—Lee equation of state (JWL-EOS) is applied to describe detonation state products for aluminized explosives. To obtain the time-dependent JWL-EOS parameters, cylinder tests and underwater explosion experiments are performed. According to the result of the wall radial velocity in cylinder tests and the shock wave pressures in underwater explosion experiments, the time-dependent JWL-EOS parameters are determined by iterating these variables in AUTODYN hydrocode simulations until the experimental values are reproduced. In addition, to verify the reliability of the derived JWL-EOS parameters, the aluminized explosive experiment is conducted in concrete. The shock wave pressures in the affected concrete bodies are measured by using manganin pressure sensors, and the rod velocity is obtained by using a high-speed camera. Simultaneously, the shock wave pressure and the rod velocity are calculated by using the derived time-dependent JWL equation of state. The calculated results are in good agreement with the experimental data.

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.

Xenon monitoring and the Comprehensive Nuclear-Test-Ban Treaty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowyer, Theodore W.

How do you monitor (verify) a CTBT? It is a difficult challenge to monitor the entire world for nuclear tests, regardless of size. Nuclear tests 'normally' occur underground, above ground or underwater. Setting aside very small tests (let's limit our thinking to 1 kiloton or more), nuclear tests shake the ground, emit large amounts of radioactivity, and make loud noises if in the atmosphere (or hydroacoustic waves if underwater)

Experimental Analysis of the Mechanism of Hearing under Water

PubMed Central

Chordekar, Shai; Kishon-Rabin, Liat; Kriksunov, Leonid; Adelman, Cahtia; Sohmer, Haim

2015-01-01

The mechanism of human hearing under water is debated. Some suggest it is by air conduction (AC), others by bone conduction (BC), and others by a combination of AC and BC. A clinical bone vibrator applied to soft tissue sites on the head, neck, and thorax also elicits hearing by a mechanism called soft tissue conduction (STC) or nonosseous BC. The present study was designed to test whether underwater hearing at low intensities is by AC or by osseous BC based on bone vibrations or by nonosseous BC (STC). Thresholds of normal hearing participants to bone vibrator stimulation with their forehead in air were recorded and again when forehead and bone vibrator were under water. A vibrometer detected vibrations of a dry human skull in all similar conditions (in air and under water) but not when water was the intermediary between the sound source and the skull forehead. Therefore, the intensities required to induce vibrations of the dry skull in water were significantly higher than the underwater hearing thresholds of the participants, under conditions when hearing by AC and osseous BC is not likely. The results support the hypothesis that hearing under water at low sound intensities may be attributed to nonosseous BC (STC). PMID:26770975

Analysing deterioration of marble stones exposed to underwater conditions

NASA Astrophysics Data System (ADS)

Cámara, Beatriz; Álvarez de Buergo, Mónica; Bethencourt, Manuel; Freire-Lista, David; Fort, Rafael

2016-04-01

The peculiar conditions of the marine environment make the conservation of underwater archaeological sites an extremely complex procedure. This is due to the fact that the prevailing conditions in this environment promote the development of deterioration phenomena in submerged artefacts through the synergistic action of physical, chemical and biological factors. The objective of the present investigation was to determine how petrophysical properties of cultural heritage materials can be affected by being exposed to the specific underwater conditions of the sea bottom, and so, to evaluate how this can affect, in a long term, in their durability and evolution when they part of an archaeological site. For this purpose, two types of marble (the Italian Carrara and the Spanish Macael) were subjected to an experiment consisting of exposing stone materials for one and a half year to underwater conditions. The experimental test was located in an archaeological site in the Bay of Cadiz (southern Spain), Bajo del Chapitel (recognized as Cultural Interest), which includes remains of shipwrecks from different periods. In this site, samples were submerged to 12 m depth and placed in the sea bottom simulating the different positions in which underwater archaeological objects can be found (fully exposed, half buried and covered). Petrophysical characterisation involved determination of the apparent and bulk densities, water saturation (maximum water content a material may contain), open porosity (porosity accessible to water), chromatic parameters and ultrasonic velocity. Before measuring, samples were subjected to mechanical cleaning (in those samples with biological colonization) and to removal of salt deposits. Results showed significant differences in these petrophysical properties after underwater submersion, which were directly related to the type of underwater exposure condition. Comparative analysis of petrophysical properties, like the one conducted in this study, provides useful information for evaluation of the deterioration processes of heritage stones in a marine environment, and for conservation measures aimed at the in situ preservation of archaeological sites. Acknowledgements: Community of Madrid for financing Geomateriales2 program (P2013/MIT2914), CEI-Moncloa UCM-UPM, Applied Petrology for Heritage Stone Materials Conservation Research Group.

Deep Learning Methods for Underwater Target Feature Extraction and Recognition

PubMed Central

Peng, Yuan; Qiu, Mengran; Shi, Jianfei; Liu, Liangliang

2018-01-01

The classification and recognition technology of underwater acoustic signal were always an important research content in the field of underwater acoustic signal processing. Currently, wavelet transform, Hilbert-Huang transform, and Mel frequency cepstral coefficients are used as a method of underwater acoustic signal feature extraction. In this paper, a method for feature extraction and identification of underwater noise data based on CNN and ELM is proposed. An automatic feature extraction method of underwater acoustic signals is proposed using depth convolution network. An underwater target recognition classifier is based on extreme learning machine. Although convolution neural networks can execute both feature extraction and classification, their function mainly relies on a full connection layer, which is trained by gradient descent-based; the generalization ability is limited and suboptimal, so an extreme learning machine (ELM) was used in classification stage. Firstly, CNN learns deep and robust features, followed by the removing of the fully connected layers. Then ELM fed with the CNN features is used as the classifier to conduct an excellent classification. Experiments on the actual data set of civil ships obtained 93.04% recognition rate; compared to the traditional Mel frequency cepstral coefficients and Hilbert-Huang feature, recognition rate greatly improved. PMID:29780407

Game Theory-Based Cooperation for Underwater Acoustic Sensor Networks: Taxonomy, Review, Research Challenges and Directions

PubMed Central

Muhammed, Dalhatu; Anisi, Mohammad Hossein; Vargas-Rosales, Cesar; Khan, Anwar

2018-01-01

Exploring and monitoring the underwater world using underwater sensors is drawing a lot of attention these days. In this field cooperation between acoustic sensor nodes has been a critical problem due to the challenging features such as acoustic channel failure (sound signal), long propagation delay of acoustic signal, limited bandwidth and loss of connectivity. There are several proposed methods to improve cooperation between the nodes by incorporating information/game theory in the node’s cooperation. However, there is a need to classify the existing works and demonstrate their performance in addressing the cooperation issue. In this paper, we have conducted a review to investigate various factors affecting cooperation in underwater acoustic sensor networks. We study various cooperation techniques used for underwater acoustic sensor networks from different perspectives, with a concentration on communication reliability, energy consumption, and security and present a taxonomy for underwater cooperation. Moreover, we further review how the game theory can be applied to make the nodes cooperate with each other. We further analyze different cooperative game methods, where their performance on different metrics is compared. Finally, open issues and future research direction in underwater acoustic sensor networks are highlighted. PMID:29389874

Game Theory-Based Cooperation for Underwater Acoustic Sensor Networks: Taxonomy, Review, Research Challenges and Directions.

PubMed

Muhammed, Dalhatu; Anisi, Mohammad Hossein; Zareei, Mahdi; Vargas-Rosales, Cesar; Khan, Anwar

2018-02-01

Exploring and monitoring the underwater world using underwater sensors is drawing a lot of attention these days. In this field cooperation between acoustic sensor nodes has been a critical problem due to the challenging features such as acoustic channel failure (sound signal), long propagation delay of acoustic signal, limited bandwidth and loss of connectivity. There are several proposed methods to improve cooperation between the nodes by incorporating information/game theory in the node's cooperation. However, there is a need to classify the existing works and demonstrate their performance in addressing the cooperation issue. In this paper, we have conducted a review to investigate various factors affecting cooperation in underwater acoustic sensor networks. We study various cooperation techniques used for underwater acoustic sensor networks from different perspectives, with a concentration on communication reliability, energy consumption, and security and present a taxonomy for underwater cooperation. Moreover, we further review how the game theory can be applied to make the nodes cooperate with each other. We further analyze different cooperative game methods, where their performance on different metrics is compared. Finally, open issues and future research direction in underwater acoustic sensor networks are highlighted.

Astronaut Bruce McCandless during an underwater test MMU/FSS in bldg 29 WETF

NASA Image and Video Library

1981-08-04

Astronaut Bruce McCandless during an underwater test of the Manned Maneuvering Unit (MMU) Flight Support Station (FSS) donning and doffing in the Bldg 29 Weightless Environment Training Facility (WETF). View is of McCandless wearing the extravehicular mobility unit (EMU), stepping into the MMU.

Underwater sightings of sea turtles in the northern Gulf of Mexico. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosman, I.; Boland, G.S.; Martin, L.

1987-10-01

Between 1975 and 1985, eight scientific studies were conducted in the northern Gulf of Mexico. The purpose here was to review the data collected from all eight studies for information concerning underwater sightings of sea turtles. Records of 1,024 scuba dives, 909 hours of underwater video and submersible observations, and some 1,500 days of time-lapse photographic observations were compiled from published reports, data logs, and photographic material. The effort yielded 268 verifiable underwater sightings of sea turtles, 231 of which came from time-lapse cameras. The majority of sightings that could be identified by species were of loggerheads. Other species sightedmore » included three leatherbacks and one Kemp's Ridley.« less

Characterization of underwater optical turbulence on the example of the Rayleigh-Benard water tank

NASA Astrophysics Data System (ADS)

Gladysz, Szymon; Barros, Rui; Kanaev, Andrey V.; Hou, Weilin

2017-09-01

For many years sound has been used as a primary method for underwater communication. However, data transmission rate of acoustic systems is low because typical frequencies associated with underwater acoustics are between tens of hertz and hundreds of kilohertz. A higher bandwidth can be achieved with visible light to transfer data underwater. The first challenge for underwater laser communication is scattering and absorption. In addition, there are disturbances caused by spatial and temporal changes in the water refraction index due to temperature and/or salinity variations. Optical turbulence, which includes the two effects, is the main theme of this paper. We will discuss the joint IOSB-NRL experiment whose goal was to test techniques for characterization of underwater optical turbulence and in particular we will focus on differential motion measurement from an LED array.

Monocular Vision-Based Underwater Object Detection

PubMed Central

Zhang, Zhen; Dai, Fengzhao; Bu, Yang; Wang, Huibin

2017-01-01

In this paper, we propose an underwater object detection method using monocular vision sensors. In addition to commonly used visual features such as color and intensity, we investigate the potential of underwater object detection using light transmission information. The global contrast of various features is used to initially identify the region of interest (ROI), which is then filtered by the image segmentation method, producing the final underwater object detection results. We test the performance of our method with diverse underwater datasets. Samples of the datasets are acquired by a monocular camera with different qualities (such as resolution and focal length) and setups (viewing distance, viewing angle, and optical environment). It is demonstrated that our ROI detection method is necessary and can largely remove the background noise and significantly increase the accuracy of our underwater object detection method. PMID:28771194

KENNEDY SPACE CENTER, FLA. - Research team members work with acoustic cable during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Research team members work with acoustic cable during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

46 CFR 115.600 - Drydock examination, internal structural examination, and underwater survey intervals.

Code of Federal Regulations, 2010 CFR

2010-10-01

... a United States port, it must undergo the required examination before sailing. (c) If your vessel is... hull exams and two internal structural exams within any five-year period. If a vessel completes a satisfactory alternate hull exam, with the underwater survey portion conducted predominantly by an approved...

A Method for Calculating the Amount of Movements to Estimate the Self-position of Manta Robots

NASA Astrophysics Data System (ADS)

Imahama, Takuya; Watanabe, Keigo; Mikuriya, Kota; Nagai, Isaku

2018-02-01

In recent years, the demand of underwater investigation is increasing in the circumference of a dam, the environmental research of the shallow where approach by ship is difficult, etc. It is known, however, that for man, all over the sea, danger exists mostly, and prolonged diving has a bad influence to a human body. Then, the development of underwater exploration robots that investigate underwater instead of humans is expected. Among underwater exploration robots, it is known that robots imitating aquatic organisms have little influence on underwater environment. Therefore, at this laboratory, a Manta robot using propulsive mechanisms with pectoral fins was developed, imitating the pectoral fin of Manta. Although underwater environmental research needs a function for estimating the self-position, it is not mounted in this Manta robot. This paper explains the amount estimation of movements using optical flows. Especially, a gimbal mechanism is introduced to reduce the influence on the optical flow calculation by pitch motion of the Manta robot. Several experiments are conducted to demonstrate the usefulness of the proposed method.

Measuring Coastal Boating Noise to Assess Potential Impacts on Marine Life

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matzner, Shari; Jones, Mark E.

2011-07-01

Article requested for submission in Sea Technology Magazine describing the Underwater Noise From Small Boats. An Overlooked Component of the Acoustic Environment in Coastal Areas. Underwater noise and its effects on marine life deserve attention as human activity in the marine environment increases. Noise can affect fish and marine mammals in ways that are physiological, as in auditory threshold shifts, and behavioral, as in changes in foraging habits. One anthropogenic source of underwater noise that has received little attention to date is recreational boating. Coastal areas and archipelago regions, which play a crucial role in the marine ecosystem, are oftenmore » subject to high levels of boat traffic. In order to better understand the noise produced by a small powerboat, a test was conducted in Sequim Bay, Washington, using an instrumented research vessel and multiple acoustic sensors. The broadband noise and narrowband peak levels were observed from two different locations while the boat was operated under various conditions. The results, combined with background noise levels, sound propagation and local boat traffic patterns, can provide a picture of the total boating noise to which marine life may be subjected.« less

First results from the NEMO Test Site

NASA Astrophysics Data System (ADS)

Riccobene, Giorgio; NEMO Collaboration

2007-03-01

The NEMO (NEutrino Mediterranean Observatory) Collaboration is constructing, 25 km E from Catania (Sicily) at 2000 m depth, an underwater test site to perform long-term tests of prototypes and new technologies for an underwater high energy neutrino detector in the Mediterranean Sea. In this framework the collaboration deployed and operated an experimental apparatus for on-line monitoring of deep-sea noise. The station is equipped with 4 hydrophones operational in the range 30 Hz - 40 kHz. This interval of frequencies matches the range suitable for acoustic detection of high energy neutrino-induced showers in water. Hydrophone signals are digitized underwater at 96 kHz sampling frequency and 24 bits resolution. A custom software was developed to record data on high resolution 4-channels PCM .le. Data are used to model underwater acoustic noise as a function of frequency and time, a mandatory parametre for future acoustic neutrino detectors. Results indicate that the average noise in the site is compatible with noise produced in condition of sea surface agitation (sea state.)

A comparison of body fat determined by underwater weighing and volume displacement.

PubMed

Ward, A; Pollock, M L; Jackson, A S; Ayres, J J; Pape, G

1978-01-01

Two hydrostatic techniques, underwater weighing and water displacement, were used to determine body fat for 67 volunteer men between 25 and 61 yr of age (-/x=41 yr). All tests were administered in random order in the morning on the same day while subjects were in the postabsorptive state. Test-retest reliabilities for the underwater weighing and water displacement techniques were 0.995 and 0.96, respectively. The correlation between the two hydrostatic techniques was r=0.96. The mean percent fat determined by underwater weighing (-/x=20.1 +/- 6.4) and water displacement (-/x=19.4 +/- 6.1) were significantly different (t=28.16; df=65; P less than 0.001). These analyses showed that both techniques were reliable in measuring percent body fat, but produced slight systematic differences. Regression equations were provided to adjust for the difference.

Underwater single beam circumferentially scanning detection system using range-gated receiver and adaptive filter

NASA Astrophysics Data System (ADS)

Tan, Yayun; Zhang, He; Zha, Bingting

2017-09-01

Underwater target detection and ranging in seawater are of interest in unmanned underwater vehicles. This study presents an underwater detection system that synchronously scans a collimated laser beam and a narrow field of view to circumferentially detect an underwater target. Hybrid methods of range-gated and variable step-size least mean squares (VSS-LMS) adaptive filter are proposed to suppress water backscattering. The range-gated receiver eliminates the backscattering of near-field water. The VSS-LMS filter extracts the target echo in the remaining backscattering and the constant fraction discriminator timing method is used to improve ranging accuracy. The optimal constant fraction is selected by analysing the jitter noise and slope of the target echo. The prototype of the underwater detection system is constructed and tested in coastal seawater, then the effectiveness of backscattering suppression and high-ranging accuracy is verified through experimental results and analysis discussed in this paper.

An energy-harvesting power supply for underwater bridge scour monitoring sensors

NASA Astrophysics Data System (ADS)

Wang, Yuli; Li, Yingjie; He, Longzhuang; Shamsi, Pourya; Zheng, Yahong R.

2018-03-01

The natural force of scouring has become one of the most critical risk endangering the endurance of bridges, thus leading to the necessity of deploying underwater monitoring sensors to actively detect potential scour holes under bridges. Due to the difficulty in re-charging batteries for underwater sensors, super capacitors with energy harvesting (EH) means are exploited to prolong the sustainability of underwater sensors. In this paper, an energy harvesting power supply based on a helical turbine is proposed to power underwater monitoring sensors. A small helical turbine is designed to convert water flow energy to electrical energy with favorable environmental robustness. A 3-inch diameter, 2.5-inch length and 3-bladed helical turbine was designed with two types of waterproof coupling with the sensor housing. Both designs were prototyped and tested under different flow conditions and we get valid voltage around 0.91 V which is enough to power monitoring sensor. The alternating current (AC) electrical energy generated by the helical turbine is then rectified and boosted to drive a DC charger for efficiently charging one super capacitor. The charging circuit was designed, prototyped and tested thoroughly with the helical turbine harvester. The results were promising, that the overall power supply can power an underwater sensor node with wireless transceivers for long-term operations

Operation of electrothermal and electrostatic MUMPs microactuators underwater

NASA Astrophysics Data System (ADS)

Sameoto, Dan; Hubbard, Ted; Kujath, Marek

2004-10-01

Surface-micromachined actuators made in multi-user MEMS processes (MUMPs) have been operated underwater without modifying the manufacturing process. Such actuators have generally been either electro-thermally or electro-statically actuated and both actuator styles are tested here for suitability underwater. This is believed to be the first time that thermal and electrostatic actuators have been compared for deflection underwater relative to air performance. A high-frequency ac square wave is used to replicate a dc-driven actuator output without the associated problem of electrolysis in water. This method of ac activation, with frequencies far above the mechanical resonance frequencies of the MEMS actuators, has been termed root mean square (RMS) operation. Both thermal and electrostatic actuators have been tested and proved to work using RMS control. Underwater performance has been evaluated by using in-air operation of these actuators as a benchmark. When comparing deflection per volt applied, thermal actuators operate between 5 and 9% of in-air deflection and electrostatic actuators show an improvement in force per volt applied of upwards of 6000%. These results agree with predictions based on the physical properties of the surrounding medium.

Underwater psychophysical audiogram of a young male California sea lion (Zalophus californianus).

PubMed

Mulsow, Jason; Houser, Dorian S; Finneran, James J

2012-05-01

Auditory evoked potential (AEP) data are commonly obtained in air while sea lions are under gas anesthesia; a procedure that precludes the measurement of underwater hearing sensitivity. This is a substantial limitation considering the importance of underwater hearing data in designing criteria aimed at mitigating the effects of anthropogenic noise exposure. To determine if some aspects of underwater hearing sensitivity can be predicted using rapid aerial AEP methods, this study measured underwater psychophysical thresholds for a young male California sea lion (Zalophus californianus) for which previously published aerial AEP thresholds exist. Underwater thresholds were measured in an aboveground pool at frequencies between 1 and 38 kHz. The underwater audiogram was very similar to those previously published for California sea lions, suggesting that the current and previously obtained psychophysical data are representative for this species. The psychophysical and previously measured AEP audiograms were most similar in terms of high-frequency hearing limit (HFHL), although the underwater HFHL was sharper and occurred at a higher frequency. Aerial AEP methods are useful for predicting reductions in the HFHL that are potentially independent of the testing medium, such as those due to age-related sensorineural hearing loss.

ABS-FishCount: An Agent-Based Simulator of Underwater Sensors for Measuring the Amount of Fish.

PubMed

García-Magariño, Iván; Lacuesta, Raquel; Lloret, Jaime

2017-11-13

Underwater sensors provide one of the possibilities to explore oceans, seas, rivers, fish farms and dams, which all together cover most of our planet's area. Simulators can be helpful to test and discover some possible strategies before implementing these in real underwater sensors. This speeds up the development of research theories so that these can be implemented later. In this context, the current work presents an agent-based simulator for defining and testing strategies for measuring the amount of fish by means of underwater sensors. The current approach is illustrated with the definition and assessment of two strategies for measuring fish. One of these two corresponds to a simple control mechanism, while the other is an experimental strategy and includes an implicit coordination mechanism. The experimental strategy showed a statistically significant improvement over the control one in the reduction of errors with a large Cohen's d effect size of 2.55.

New ultrasensitive pickup device for deep-sea robots: underwater super-HARP color TV camera

NASA Astrophysics Data System (ADS)

Maruyama, Hirotaka; Tanioka, Kenkichi; Uchida, Tetsuo

1994-11-01

An ultra-sensitive underwater super-HARP color TV camera has been developed. The characteristics -- spectral response, lag, etc. -- of the super-HARP tube had to be designed for use underwater because the propagation of light in water is very different from that in air, and also depends on the light's wavelength. The tubes have new electrostatic focusing and magnetic deflection functions and are arranged in parallel to miniaturize the camera. A deep sea robot (DOLPHIN 3K) was fitted with this camera and used for the first sea test in Sagami Bay, Japan. The underwater visual information was clear enough to promise significant improvements in both deep sea surveying and safety. It was thus confirmed that the Super- HARP camera is very effective for underwater use.

Determining spherical lens correction for astronaut training underwater.

PubMed

Porter, Jason; Gibson, C Robert; Strauss, Samuel

2011-09-01

To develop a model that will accurately predict the distance spherical lens correction needed to be worn by National Aeronautics and Space Administration astronauts while training underwater. The replica space suit's helmet contains curved visors that induce refractive power when submersed in water. 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. The helmet's 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. 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.

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

In-air versus underwater comparison of 3D reconstruction accuracy using action sport cameras.

PubMed

Bernardina, Gustavo R D; Cerveri, Pietro; Barros, Ricardo M L; Marins, João C B; Silvatti, Amanda P

2017-01-25

Action sport cameras (ASC) have achieved a large consensus for recreational purposes due to ongoing cost decrease, image resolution and frame rate increase, along with plug-and-play usability. Consequently, they have been recently considered for sport gesture studies and quantitative athletic performance evaluation. In this paper, we evaluated the potential of two ASCs (GoPro Hero3+) for in-air (laboratory) and underwater (swimming pool) three-dimensional (3D) motion analysis as a function of different camera setups involving the acquisition frequency, image resolution and field of view. This is motivated by the fact that in swimming, movement cycles are characterized by underwater and in-air phases what imposes the technical challenge of having a split volume configuration: an underwater measurement volume observed by underwater cameras and an in-air measurement volume observed by in-air cameras. The reconstruction of whole swimming cycles requires thus merging of simultaneous measurements acquired in both volumes. Characterizing and optimizing the instrumental errors of such a configuration makes mandatory the assessment of the instrumental errors of both volumes. In order to calibrate the camera stereo pair, black spherical markers placed on two calibration tools, used both in-air and underwater, and a two-step nonlinear optimization were exploited. The 3D reconstruction accuracy of testing markers and the repeatability of the estimated camera parameters accounted for system performance. For both environments, statistical tests were focused on the comparison of the different camera configurations. Then, each camera configuration was compared across the two environments. In all assessed resolutions, and in both environments, the reconstruction error (true distance between the two testing markers) was less than 3mm and the error related to the working volume diagonal was in the range of 1:2000 (3×1.3×1.5m 3 ) to 1:7000 (4.5×2.2×1.5m 3 ) in agreement with the literature. Statistically, the 3D accuracy obtained in the in-air environment was poorer (p<10 -5 ) than the one in the underwater environment, across all the tested camera configurations. Related to the repeatability of the camera parameters, we found a very low variability in both environments (1.7% and 2.9%, in-air and underwater). This result encourage the use of ASC technology to perform quantitative reconstruction both in-air and underwater environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Kinematic and EMG data during underwater dolphin kick change while synchronizing with or without synchronization of kick frequency with the beat of a metronome.

PubMed

Yamakawa, Keisuke Kobayashi; Shimojo, Hirofumi; Takagi, Hideki; Tsubakimoto, Shozo; Sengoku, Yasuo

2017-10-01

We investigated the effects of synchronizing kick frequency with the beat of a metronome on kinematic and electromyographic (EMG) parameters during the underwater dolphin kick as a pilot study related to the research that entitled " Effect of increased kick frequency on propelling efficiency and muscular co-activation during underwater dolphin kick" (Yamakawa et al., 2017) [1]. Seven collegiate female swimmers participated in this experiment. The participants conducted two underwater dolphin kick trials: swimming freely at maximum effort, and swimming while synchronizing the kick frequency of maximum effort with the beat of a metronome. The kinematic parameters during the underwater dolphin kick were calculated by 2-D motion analysis, and surface electromyographic measurements were taken from six muscles (rectus abdominis, erector spinae, rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius). The results revealed no significant differences in the kinematic and EMG parameters between trials of the two swimming techniques. Therefore, the action of synchronizing the kick frequency with the beat of a metronome did not affect movement or muscle activity during the underwater dolphin kick in this experiment.

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.

NEW TECHNOLOGY FOR CONDUCTING RADIATION HAZARD ASSESSMENTS: THE APPLICATION OF THE UNDERWATER RADIATION SPECTRAL IDENTIFICATION SYSTEM (URSIS) AT THE MASSACHUSETTS BAY INDUSTRIAL WASTE (SITE) (U.S.A.)

EPA Science Inventory

The Underwater Radiation Spectral Identification System (URSIS) is a portable spectrometer used for the in situ detection of radioactivity in the marine environment. This paper reports on the first time application of this technology to assess, in a preliminary manner, the potent...

Evaluation of electrical conductivity of Cu and Al through sub microsecond underwater electrical wire explosion

NASA Astrophysics Data System (ADS)

Sheftman, D.; Shafer, D.; Efimov, S.; Krasik, Ya. E.

2012-03-01

Sub-microsecond timescale underwater electrical wire explosions using Cu and Al materials have been conducted. Current and voltage waveforms and time-resolved streak images of the discharge channel, coupled to 1D magneto-hydrodynamic simulations, have been used to determine the electrical conductivity of the metals for the range of conditions between hot liquid metal and strongly coupled non-ideal plasma, in the temperature range of 10-60 KK. The results of these studies showed that the conductivity values obtained are typically lower than those corresponding to modern theoretical electrical conductivity models and provide a transition between the conductivity values obtained in microsecond time scale explosions and those obtained in nanosecond time scale wire explosions. In addition, the measured wire expansion shows good agreement with equation of state tables.

Underwater Concrete Inspection Equipment

DTIC Science & Technology

1991-04-01

nondestructive testing of con- crete waterfront structures. One instrument is a magnetic rebar locator that locates rebar in concrete structures and measures the...amount of con- crete cover over the rebar . Another instrument is a rebound hammer that measures the surface hardness of the concrete . The third...development of three specialized instruments for the underwater nondestructive testing or concrete waterfront structures. One instrument is a magnetic rebar

Effect of coordination movement using the PNF pattern underwater on the balance and gait of stroke patients

PubMed Central

Kim, Kyoung; Lee, Dong-Kyu; Jung, Sang-In

2015-01-01

[Purpose] To investigate the effect of coordination movement using the Proprioceptive Neuromuscular Facilitation pattern underwater on the balance and gait of stroke patients. [Subjects and Methods] Twenty stroke patients were randomly assigned to an experimental group that performed coordination movement using the Proprioceptive Neuromuscular Facilitation pattern underwater and a control group (n =10 each). Both the groups underwent neurodevelopmental treatment, and the experimental group performed coordination movement using the Proprioceptive neuromuscular facilitation pattern underwater. Balance was measured using the Berg Balance Scale and Functional Reach Test, and gait was measured using the 10-Meter Walk Test and Timed Up and Go Test. To compare in-group data before and after the intervention, paired t-test was used. Independent t-test was used to compare differences in the results of the Berg Balance Scale, Functional Reach Test, 10-Meter Walk Test, and Timed Up and Go Test before and after the intervention between the groups. [Results] Comparison within the groups showed significant differences in the results of the Berg Balance Scale, Functional Reach Test, 10-Meter Walk Test, and Timed Up and Go Test before and after the experimental intervention. On comparison between the groups, there were greater improvements in the scores of the Berg Balance Scale, Functional Reach Test, 10-Meter Walk Test, and Timed Up and Go Test in the experimental group. [Conclusion] The findings demonstrate that coordination movement using the Proprioceptive Neuromuscular Facilitation pattern under water has a significant effect on the balance and gait of stroke patients. PMID:26834335

Underwater hearing and sound localization with and without an air interface.

PubMed

Shupak, Avi; Sharoni, Zohara; Yanir, Yoav; Keynan, Yoav; Alfie, Yechezkel; Halpern, Pinchas

2005-01-01

Underwater hearing acuity and sound localization are improved by the presence of an air interface around the pinnae and inside the external ear canals. Hearing threshold and the ability to localize sound sources are reduced underwater. The resonance frequency of the external ear is lowered when the external ear canal is filled with water, and the impedance-matching ability of the middle ear is significantly reduced due to elevation of the ambient pressure, the water-mass load on the tympanic membrane, and the addition of a fluid-air interface during submersion. Sound lateralization on land is largely explained by the mechanisms of interaural intensity differences and interaural temporal or phase differences. During submersion, these differences are largely lost due to the increase in underwater sound velocity and cancellation of the head's acoustic shadow effect because of the similarity between the impedance of the skull and the surrounding water. Ten scuba divers wearing a regular opaque face mask or an opaque ProEar 2000 (Safe Dive, Ltd., Hofit, Israel) mask that enables the presence of air at ambient pressure in and around the ear made a dive to a depth of 3 m in the open sea. Four underwater speakers arranged on the horizontal plane at 90-degree intervals and at a distance of 5 m from the diver were used for testing pure-tone hearing thresholds (PTHT), the reception threshold for the recorded sound of a rubber-boat engine, and sound localization. For sound localization, the sound of the rubber boat's engine was randomly delivered by one speaker at a time at 40 dB HL above the recorded sound of a rubber-boat engine, and the diver was asked to point to the sound source. The azimuth was measured by the diver's companion using a navigation board. Underwater PTHT with both masks were significantly higher for frequencies of 250 to 6000 Hz when compared with the thresholds on land (p <0.0001). No differences were found in the PTHT or the reception threshold for the recorded sound of a rubber-boat engine for dry or wet ear conditions. There was no difference in the sound localization error between the regular mask and the ProEar 2000 mask. The presence of air around the pinna and inside the external ear canal did not improve underwater hearing sensitivity or sound localization. These results support the argument that bone conduction plays the main role in underwater hearing.

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

NEEMO 21: Tools, Techniques, Technologies & Training for Science Exploration EVA

NASA Technical Reports Server (NTRS)

Graff, Trevor

2016-01-01

The 21st mission of the NASA Extreme Environment Mission Operations (NEEMO) was a highly integrated operational test and evaluation of tools, techniques, technologies, and training for science driven exploration during Extravehicular Activity (EVA).The 16-day mission was conducted from the Aquarius habitat, an underwater laboratory, off the coast of Key Largo, FL. The unique facility, authentic science objectives, and diverse skill-sets of the crew/team facilitate the planning and design for future space exploration.

Modeling Gas Bubble Behaviour and Loading on a Rigid Target due to Close-Proximity Underwater Explosions: Comparison to Tests Conducted at DRDC Suffield

DTIC Science & Technology

2010-11-01

rayon de bulle de type champ libre, d’une cible rigide. À cette distance de sécurité, l’onde de choc et la bulle de gaz contribuent de façon...produisent des prédictions d’impulsion améliorées pour les cibles rigides. DRDC Atlantic TM 2010-238 iii Executive summary Modeling...i Executive summary

A velocity probe-based method for continuous detonation and shock measurement in near-field underwater explosion.

PubMed

Li, Kebin; Li, Xiaojie; Yan, Honghao; Wang, Xiaohong; Miao, Yusong

2017-12-01

A new velocity probe which permits recording the time history of detonation and shock waves has been developed by improving the commercial on principle and structure. A method based on the probe is then designed to measure the detonation velocity and near-field shock parameters in a single underwater explosion, by which the oblique shock wave front of cylindrical charges and the peak pressure attenuation curve of spherical explosive are obtained. A further derivation of detonation pressure, adiabatic exponent, and other shock parameters is conducted. The present method offers a novel and reliable parameter determination for near-field underwater explosion.

A velocity probe-based method for continuous detonation and shock measurement in near-field underwater explosion

NASA Astrophysics Data System (ADS)

Li, Kebin; Li, Xiaojie; Yan, Honghao; Wang, Xiaohong; Miao, Yusong

2017-12-01

A new velocity probe which permits recording the time history of detonation and shock waves has been developed by improving the commercial on principle and structure. A method based on the probe is then designed to measure the detonation velocity and near-field shock parameters in a single underwater explosion, by which the oblique shock wave front of cylindrical charges and the peak pressure attenuation curve of spherical explosive are obtained. A further derivation of detonation pressure, adiabatic exponent, and other shock parameters is conducted. The present method offers a novel and reliable parameter determination for near-field underwater explosion.

KENNEDY SPACE CENTER, FLA. - Researchers are positioned on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Researchers are positioned on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Dr. Grant Gilmore (left), Dynamac Corp., talks to another member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Dr. Grant Gilmore (left), Dynamac Corp., talks to another member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Joe Bartoszek, NASA, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Joe Bartoszek, NASA, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members take their places on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members take their places on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

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.

UTOFIA: an underwater time-of-flight image acquisition system

NASA Astrophysics Data System (ADS)

Driewer, Adrian; Abrosimov, Igor; Alexander, Jonathan; Benger, Marc; O'Farrell, Marion; Haugholt, Karl Henrik; Softley, Chris; Thielemann, Jens T.; Thorstensen, Jostein; Yates, Chris

2017-10-01

In this article the development of a newly designed Time-of-Flight (ToF) image sensor for underwater applications is described. The sensor is developed as part of the project UTOFIA (underwater time-of-flight image acquisition) funded by the EU within the Horizon 2020 framework. This project aims to develop a camera based on range gating that extends the visible range compared to conventional cameras by a factor of 2 to 3 and delivers real-time range information by means of a 3D video stream. The principle of underwater range gating as well as the concept of the image sensor are presented. Based on measurements on a test image sensor a pixel structure that suits best to the requirements has been selected. Within an extensive characterization underwater the capability of distance measurements in turbid environments is demonstrated.

Geometric and Optic Characterization of a Hemispherical Dome Port for Underwater Photogrammetry

PubMed Central

Menna, Fabio; Nocerino, Erica; Fassi, Francesco; Remondino, Fabio

2016-01-01

The popularity of automatic photogrammetric techniques has promoted many experiments in underwater scenarios leading to quite impressive visual results, even by non-experts. Despite these achievements, a deep understanding of camera and lens behaviors as well as optical phenomena involved in underwater operations is fundamental to better plan field campaigns and anticipate the achievable results. The paper presents a geometric investigation of a consumer grade underwater camera housing, manufactured by NiMAR and equipped with a 7′′ dome port. After a review of flat and dome ports, the work analyzes, using simulations and real experiments, the main optical phenomena involved when operating a camera underwater. Specific aspects which deal with photogrammetric acquisitions are considered with some tests in laboratory and in a swimming pool. Results and considerations are shown and commented. PMID:26729133

Underwater Acoustic Source Localisation Among Blind and Sighted Scuba Divers: Comparative study.

PubMed

Cambi, Jacopo; Livi, Ludovica; Livi, Walter

2017-05-01

Many blind individuals demonstrate enhanced auditory spatial discrimination or localisation of sound sources in comparison to sighted subjects. However, this hypothesis has not yet been confirmed with regards to underwater spatial localisation. This study therefore aimed to investigate underwater acoustic source localisation among blind and sighted scuba divers. This study took place between February and June 2015 in Elba, Italy, and involved two experimental groups of divers with either acquired (n = 20) or congenital (n = 10) blindness and a control group of 30 sighted divers. Each subject took part in five attempts at an under-water acoustic source localisation task, in which the divers were requested to swim to the source of a sound originating from one of 24 potential locations. The control group had their sight obscured during the task. The congenitally blind divers demonstrated significantly better underwater sound localisation compared to the control group or those with acquired blindness ( P = 0.0007). In addition, there was a significant correlation between years of blindness and underwater sound localisation ( P <0.0001). Congenital blindness was found to positively affect the ability of a diver to recognise the source of a sound in an underwater environment. As the correct localisation of sounds underwater may help individuals to avoid imminent danger, divers should perform sound localisation tests during training sessions.

Leaf gas films, underwater photosynthesis and plant species distributions in a flood gradient.

PubMed

Winkel, Anders; Visser, Eric J W; Colmer, Timothy D; Brodersen, Klaus P; Voesenek, Laurentius A C J; Sand-Jensen, Kaj; Pedersen, Ole

2016-07-01

Traits for survival during flooding of terrestrial plants include stimulation or inhibition of shoot elongation, aerenchyma formation and efficient gas exchange. Leaf gas films form on superhydrophobic cuticles during submergence and enhance underwater gas exchange. The main hypothesis tested was that the presence of leaf gas films influences the distribution of plant species along a natural flood gradient. We conducted laboratory experiments and field observations on species distributed along a natural flood gradient. We measured presence or absence of leaf gas films and specific leaf area of 95 species. We also measured, gas film retention time during submergence and underwater net photosynthesis and dark respiration of 25 target species. The presence of a leaf gas film was inversely correlated to flood frequency and duration and reached a maximum value of 80% of the species in the rarely flooded locations. This relationship was primarily driven by grasses that all, independently of their field location along the flood gradient, possess gas films when submerged. Although the present study and earlier experiments have shown that leaf gas films enhance gas exchange of submerged plants, the ability of species to form leaf gas films did not show the hypothesized relationship with species composition along the flood gradient. © 2016 John Wiley & Sons Ltd.

Underwater auditory localization by a swimming harbor seal (Phoca vitulina).

PubMed

Bodson, Anais; Miersch, Lars; Mauck, Bjoern; Dehnhardt, Guido

2006-09-01

The underwater sound localization acuity of a swimming harbor seal (Phoca vitulina) was measured in the horizontal plane at 13 different positions. The stimulus was either a double sound (two 6-kHz pure tones lasting 0.5 s separated by an interval of 0.2 s) or a single continuous sound of 1.2 s. Testing was conducted in a 10-m-diam underwater half circle arena with hidden loudspeakers installed at the exterior perimeter. The animal was trained to swim along the diameter of the half circle and to change its course towards the sound source as soon as the signal was given. The seal indicated the sound source by touching its assumed position at the board of the half circle. The deviation of the seals choice from the actual sound source was measured by means of video analysis. In trials with the double sound the seal localized the sound sources with a mean deviation of 2.8 degrees and in trials with the single sound with a mean deviation of 4.5 degrees. In a second experiment minimum audible angles of the stationary animal were found to be 9.8 degrees in front and 9.7 degrees in the back of the seal's head.

Design and implementation of an underwater sound recording device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez, Jayson J.; Myers, Joshua R.; Carlson, Thomas J.

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 performedmore » 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.« less

Inspecting the inside of underwater hull

NASA Astrophysics Data System (ADS)

Valkovic, Vladivoj; Sudac, Davorin

2009-05-01

In order to demonstrate the possibility of identifying the material within ship's underwater hull, sunken ships and other objects on the sea floor tests with the 14 MeV sealed tube neutron generator incorporated inside a small submarine submerged in the test basin filled with sea water have been performed. Results obtained for inspection of diesel fuel and explosive presence behind single and double hull constructions are presented.

Simulation and preparation of surface EVA in reduced gravity at the Marseilles Bay subsea analogue sites

NASA Astrophysics Data System (ADS)

Weiss, P.; Gardette, B.; Chirié, B.; Collina-Girard, J.; Delauze, H. G.

2012-12-01

Extravehicular activity (EVA) of astronauts during space missions is simulated nowadays underwater in neutral buoyancy facilities. Certain aspects of weightlessness can be reproduced underwater by adding buoyancy to a diver-astronaut, therefore exposing the subject to the difficulties of working without gravity. Such tests were done at the COMEX' test pool in Marseilles in the 1980s to train for a French-Russian mission to the MIR station, for the development of the European HERMES shuttle and the COLUMBUS laboratory. However, space agencies are currently studying missions to other destinations than the International Space Station in orbit, such as the return to the Moon, NEO (near-Earth objects) or Mars. All these objects expose different gravities: Moon has one sixth of Earth's gravity, Mars has a third of Earth's gravity and asteroids have virtually no surface gravity; the astronaut "floats" above the ground. The preparation of such missions calls for a new concept in neutral buoyancy training, not on man-made structures, but on natural terrain, underwater, to simulate EVA operations such as sampling, locomotion or even anchoring in low gravity. Underwater sites can be used not only to simulate the reduced gravity that astronauts will experience during their field trips, also human factors like stress are more realistically reproduced in such environment. The Bay of Marseille hosts several underwater sites that can be used to simulate various geologic morphologies, such as sink-holes which can be used to simulate astronaut descends into craters, caves where explorations of lava tubes can be trained or monolithic rock structures that can be used to test anchoring devices (e.g., near Earth objects). Marseilles with its aerospace and maritime/offshore heritage hosts the necessary logistics and expertise that is needed to perform such simulations underwater in a safe manner (training of astronaut-divers in local test pools, research vessels, subsea robots and submarines). COMEX is currently preparing a space mission simulation in the Marseilles Bay (foreseen in June 2012), and the paper will give an overview of the different underwater analogue sites that are available to the scientific community for the simulation of surface EVA or the test of scientific instruments and devices.

Effect of Boric Acid Concentration on Viscosity of Slag and Property of Weld Metal Obtained from Underwater Wet Welding

NASA Astrophysics Data System (ADS)

Guo, Ning; Guo, Wei; Xu, Changsheng; Du, Yongpeng; Feng, Jicai

2015-06-01

Underwater wet welding is a crucial repair and maintenance technology for nuclear plant. A boric acid environment raises a new challenge for the underwater welding maintenance of nuclear plant. This paper places emphasis on studying the influence of a boric acid environment in nuclear plant on the underwater welding process. Several groups of underwater wet welding experiments have been conducted in boric acid aqueous solution with different concentration (0-35000 ppm). The viscosity of the welding slag and the mechanical properties of welds, such as the hardness, strength, and elongation, have been studied. The results show that with increasing boric acid concentration, the viscosity of the slag decreases first and then increases at a lower temperature (less than 1441 °C). However, when the temperature is above 1480 °C, the differences between the viscosity measurements become less pronounced, and the viscosity tends to a constant value. The hardness and ductility of the joints can be enhanced significantly, and the maximum strength of the weld metal can be reached at 2300 ppm.

A Hierarchical Communication Architecture for Oceanic Surveillance Applications

PubMed Central

Macias, Elsa; Suarez, Alvaro; Chiti, Francesco; Sacco, Andrea; Fantacci, Romano

2011-01-01

The interest in monitoring applications using underwater sensor networks has been growing in recent years. The severe communication restrictions imposed by underwater channels make that efficient monitoring be a challenging task. Though a lot of research has been conducted on underwater sensor networks, there are only few concrete applications to a real-world case study. In this work, hence, we propose a general three tier architecture leveraging low cost wireless technologies for acoustic communications between underwater sensors and standard technologies, Zigbee and Wireless Fidelity (WiFi), for water surface communications. We have selected a suitable Medium Access Control (MAC) layer, after making a comparison with some common MAC protocols. Thus the performance of the overall system in terms of Signals Discarding Rate (SDR), signalling delay at the surface gateway as well as the percentage of true detection have been evaluated by simulation, pointing out good results which give evidence in applicability’s favour. PMID:22247669

Reduction of the Radiating Sound of a Submerged Finite Cylindrical Shell Structure by Active Vibration Control

PubMed Central

Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok

2013-01-01

In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water. PMID:23389344

Reduction of the radiating sound of a submerged finite cylindrical shell structure by active vibration control.

PubMed

Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok

2013-02-06

In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

DECOMPRESSION FROM He-N2-O2 (TRIMIX) BOUNCE DIVES IS NOT MORE EFFICIENT THAN FROM He-O2 (HELIOX) BOUNCE DIVES

DTIC Science & Technology

2015-05-28

true, trimix would be an attractive alternative to heliox for U. S. Navy MK 16 MOD 1 underwater breathing apparatus (UBA) diving. However, there is no...for the semi-closed circuit Canadian Underwater Mine-countermeasures Apparatus (CUMA) that are shorter than...diving15-17 and by the U.S. Navy for the MK 6 semi- closed circuit underwater breathing apparatus (UBA);18,19 each of these programs tested trimix schedules

Photogrammetry in maritime and underwater archaeology: two marble wrecks from Sicily

NASA Astrophysics Data System (ADS)

Balletti, C.; Beltrame, C.; Costa, E.; Guerra, F.; Vernier, P.

2015-06-01

Underwater survey, compared to land archaeology, needs some specific techniques, because the application of some active 3D sensor, such as laser scanner, is obviously impossible. The necessity to produce three-dimensional survey, offering the same accuracy of classical terrestrial laserscanning or photogrammetric methods, combined with the request of low costs and rapid solutions, led the researchers to test and apply oftentimes image-based techniques. In the last two years the Ca' Foscari University and University IUAV of Venice are conducting a research on the application of integrated techniques to support underwater metric documentation, comparing them to the manual traditional one. The gained experience (and confirmed by other recently published papers) shows that the actual multiimage digital photogrammetry is a good solution for the underwater archaeology. This approach is useful both from a metric and from a recording point of view, because it achieves high quality results, such as accurate 3D models or 2D representations, offering a complete documentation of underwater sites. But photogrammetry has to be supported by a topographical survey (to acquire ground control points - GCP) to georeference all the finds in the same reference system. This paper presents the integrated survey of two roman shipwrecks, approaching differently in the GCP's acquisition just for the different morphological characteristic of the sites. The wrecks' cargos are huge marble blocks, presenting differences in quantities, layout and depths. Those characteristics determine the choice of the topographic survey. The results of the survey are two 3D polygonal textured models of the sites, which can be easily used for different analyses and reconstructive hypothesis, opening new possibilities of documentation with both specialists and the wider public. Furthermore, 3D models are the geometric base for 2D orthophoto and cross section extraction. The paper will illustrate all the phases regarding the survey's design, acquisition and realization and the data processing to obtain 2D and 3D final representation.

Efficient system for wavenumber-frequency analysis of underwater structures

NASA Astrophysics Data System (ADS)

Boober, Walter H.; Morton, David; Gedney, Charles; Abbot, Philip

1998-06-01

A watertight housing was developed to a low a scanning laser vibrometer (SLV) system to work underwater. Compared to other underwater optical measurement systems, this system offers distinct advantages, including ease of adaptation to a variety of teste, no requirement to be near tank windows, and a simplified rigging system. The system was recently sued to successfully conduct a wavenumber frequency evaluation of the vibratory response of a submerged cylindrical shell. The technical issues in developing the housing and assuring the integrity of the SLV accuracy during transition to underwater use will be discussed. Also, problems encountered in maximizing return signal strength, preparation of the shell, and the process of on-sight data transfer for quick-look wavenumber-frequency analysis while data are being acquired will be presented. The cylindrical shell was excited with 100 to 5000 Hz chirp signals by a 44 N shaker that was attached axially at the center of a bulkhead. A scan consisted of 3 columns with 64 measurement points per column. The shell was rotated 11.25 degrees and the scan repeated to collect an array of 32 by 64 equally spaced points totalling 6144 measurements. The time of data acquisition was about 11 hours. This underwater housing permitted the type of measurements that are not readily available with other systems. With most other techniques the collection time would have been significantly longer. The transfer functions between the velocities measured at each scan location and the shaker force signal were computed as functions of frequency. The transfer functions computed for the center scan columns were then transformed into the wavevector domain using a 2D FFT program. Preliminary results show that the shell response is concentrated near zero circumferential wavenumber, due to the axial symmetry of the driving force. Further, the maximum shell response is also concentrated near the ring frequency of the cylinder, at an axial wavenumber of about -20 rad/m.

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 acoustic and RF signals to enhance the capability of the nodes to communicate over greater distances. The AUVs will need to avoid obstacles and maneuver around to collect data based on predefined algorithms. Thus, they will be provided with two positioning systems; the inertial navigation system, backed with an acoustic positioning system to mitigate drift. The AUVs divide the ocean into planes and explore along circular paths increasing in diameter with depth. Moreover, they make use of miniaturized sensors to map the surrounding environment. In this paper, the ROV and the submersibles are described, along with sections explaining the mechanism of communication and the testing procedures conducted to yield results.

Underwater Mapping Results for Seabotix vLBV300 Vehicle with Tritech Gemini 720i Imaging Sonar near Newport, OR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hollinger, Geoffrey

This document presents results from tests to demonstrate underwater mapping capabilities of an underwater vehicle in conditions typically found in marine renewable energy arrays. These tests were performed with a tethered Seabotix vLBV300 underwater vehicle. The vehicle is equipped with an inertial navigation system (INS) based on a Gladiator Landmark 40 IMU and Teledyne Explorer Doppler Velocity Log, as well as a Gemini 720i scanning sonar acquired from Tritech. The results presented include both indoor pool and offshore deployments. The indoor pool deployments were performed on October 7, 2016 and February 3, 2017 in Corvallis, OR. The offshore deployment wasmore » performed on April 20, 2016 off the coast of Newport, OR (44.678 degrees N, 124.109 degrees W). During the mission period, the sea state varied between 3 and 4, with an average significant wave height of 1.6 m. Data was recorded from both the INS and the sonar.« less

ABS-FishCount: An Agent-Based Simulator of Underwater Sensors for Measuring the Amount of Fish

PubMed Central

2017-01-01

Underwater sensors provide one of the possibilities to explore oceans, seas, rivers, fish farms and dams, which all together cover most of our planet’s area. Simulators can be helpful to test and discover some possible strategies before implementing these in real underwater sensors. This speeds up the development of research theories so that these can be implemented later. In this context, the current work presents an agent-based simulator for defining and testing strategies for measuring the amount of fish by means of underwater sensors. The current approach is illustrated with the definition and assessment of two strategies for measuring fish. One of these two corresponds to a simple control mechanism, while the other is an experimental strategy and includes an implicit coordination mechanism. The experimental strategy showed a statistically significant improvement over the control one in the reduction of errors with a large Cohen’s d effect size of 2.55. PMID:29137165

Investigation of charge weight and shock factor effect on non-linear transient structural response of rectangular plates subjected to underwater explosion (UNDEX) shock loading

NASA Astrophysics Data System (ADS)

Demir, Ozgur; Sahin, Abdurrahman; Yilmaz, Tamer

2012-09-01

Underwater explosion induced shock loads are capable of causing considerable structural damage. Investigations of the underwater explosion (UNDEX) effects on structures have seen continuous developments because of security risks. Most of the earlier experimental investigations were performed by military since the World War I. Subsequently; Cole [1] established mathematical relations for modeling underwater explosion shock loading, which were the outcome of many experimental investigations This study predicts and establishes the transient responses of a panel structure to underwater explosion shock loads using non-linear finite element code Ls-Dyna. Accordingly, in this study a new MATLAB code has been developed for predicting shock loading profile for different weight of explosive and different shock factors. Numerical analysis was performed for various test conditions and results are compared with Ramajeyathilagam's experimental study [8].

Study of archaeological underwater finds: deterioration and conservation

NASA Astrophysics Data System (ADS)

Crisci, G. M.; La Russa, M. F.; Macchione, M.; Malagodi, M.; Palermo, A. M.; Ruffolo, S. A.

2010-09-01

This study is aimed at an assessment of the methodologies, instruments and new applications for underwater archaeology. Research focused on study of the various kinds of degradation affecting underwater finds and stone materials aged in underwater environment, efficiency evaluation of various surface cleaning methods and study and mixing of protective products with consolidating resins and antimicrobial biocides to be applied to restored underwater finds. Transmitted light optical microscopy and scanning electron microscopy (SEM) were used to study surface biofilms and the interactions with samples of different stone materials such as brick, marble and granite immersed in the submarine archaeological area of Crotone (South of Italy). Surface cleaning tests were performed with application of ion exchange resins, EDTA, hydrogen peroxide and ultrasound techniques. Capillary water absorption, simulated solar ageing and colourimetric measurements were carried out to evaluate hydrophobic and consolidant properties; to assess biocidal efficacy, heterotrophic micro-organisms ( Aspergillus niger) were inoculated on agar plates and growth inhibition was measured.

Three-dimensional model of hydro acoustic channel for research MIMO systems

NASA Astrophysics Data System (ADS)

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

2017-05-01

Currently, wireless hydroacoustic modems are actively being developed, which are used to provide efficient data transmission in the hydroacoustic channel. Such kind of developments are relevant for today, as they are used in various fields of science and fields of activity. An example is the connection with underwater vehicles for scientific, research, search and rescue purposes. Development of this kind of communication systems (modems) is a difficult task, as signal propagation is affected by various factors. As a result, the transfer characteristic changes with time, thereby imposing restrictions on the acoustic communication channel. In this regard, the researchers began the task of further study sonar environment and get a detailed mathematical description of the underwater channel. For this, a huge number of field tests were conducted, aimed at studying the underwater acoustic environment. However, the results of the research are always limited by the conditions in which the test took place. Therefore, it is not always possible to apply these results to the required conditions. All of the above features do not allow you to create some kind of a commonly accepted model for the acoustic channel, as studies based on experiments, collected in localized environments without generalizations. This paper presents, the three-dimensional model of the sonar channel for MIMO systems in the coastal zone, based on the acoustic signal propagation characteristics in the presence of multiple paths, the influence of the Doppler effect (as a result of mobile and / or base station traffic), in terms of signal attenuation, receiver characteristics influence and Transmitting antenna, etc.

Underwater Acoustic Source Localisation Among Blind and Sighted Scuba Divers

PubMed Central

Cambi, Jacopo; Livi, Ludovica; Livi, Walter

2017-01-01

Objectives Many blind individuals demonstrate enhanced auditory spatial discrimination or localisation of sound sources in comparison to sighted subjects. However, this hypothesis has not yet been confirmed with regards to underwater spatial localisation. This study therefore aimed to investigate underwater acoustic source localisation among blind and sighted scuba divers. Methods This study took place between February and June 2015 in Elba, Italy, and involved two experimental groups of divers with either acquired (n = 20) or congenital (n = 10) blindness and a control group of 30 sighted divers. Each subject took part in five attempts at an under-water acoustic source localisation task, in which the divers were requested to swim to the source of a sound originating from one of 24 potential locations. The control group had their sight obscured during the task. Results The congenitally blind divers demonstrated significantly better underwater sound localisation compared to the control group or those with acquired blindness (P = 0.0007). In addition, there was a significant correlation between years of blindness and underwater sound localisation (P <0.0001). Conclusion Congenital blindness was found to positively affect the ability of a diver to recognise the source of a sound in an underwater environment. As the correct localisation of sounds underwater may help individuals to avoid imminent danger, divers should perform sound localisation tests during training sessions. PMID:28690888

Constrained Surface-Level Gateway Placement for Underwater Acoustic Wireless Sensor Networks

NASA Astrophysics Data System (ADS)

Li, Deying; Li, Zheng; Ma, Wenkai; Chen, Hong

One approach to guarantee the performance of underwater acoustic sensor networks is to deploy multiple Surface-level Gateways (SGs) at the surface. This paper addresses the connected (or survivable) Constrained Surface-level Gateway Placement (C-SGP) problem for 3-D underwater acoustic sensor networks. Given a set of candidate locations where SGs can be placed, our objective is to place minimum number of SGs at a subset of candidate locations such that it is connected (or 2-connected) from any USN to the base station. We propose a polynomial time approximation algorithm for the connected C-SGP problem and survivable C-SGP problem, respectively. Simulations are conducted to verify our algorithms' efficiency.

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

NEMO-SMO acoustic array: A deep-sea test of a novel acoustic positioning system for a km3-scale underwater neutrino telescope

NASA Astrophysics Data System (ADS)

Viola, S.; Ardid, M.; Bertin, V.; Enzenhöfer, A.; Keller, P.; Lahmann, R.; Larosa, G.; Llorens, C. D.; NEMO Collaboration; SMO Collaboration

2013-10-01

Within the activities of the NEMO project, the installation of a 8-floors tower (NEMO-Phase II) at a depth of 3500 m is foreseen in 2012. The tower will be installed about 80 km off-shore Capo Passero, in Sicily. On board the NEMO tower, an array of 18 acoustic sensors will be installed, permitting acoustic detection of biological sources, studies for acoustic neutrino detection and primarily acoustic positioning of the underwater structures. For the latter purpose, the sensors register acoustic signals emitted by five acoustic beacons anchored on the sea-floor. The data acquisition system of the acoustic sensors is fully integrated with the detector data transport system and is based on an “all data to shore” philosophy. Signals coming from hydrophones are continuously sampled underwater at 192 kHz/24 bit and transmitted to shore through an electro-optical cable for real-time analysis. A novel technology for underwater GPS time-stamping of data has been implemented and tested. The operation of the acoustic array will permit long-term test of sensors and electronics technologies that are proposed for the acoustic positioning system of KM3NeT.

An Aquatic Acoustic Metrics Interface Utility for Underwater Sound Monitoring and Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Huiying; Halvorsen, Michele B.; Deng, Zhiqun

Fishes and other marine mammals suffer a range of potential effects from intense sound sources generated by anthropogenic underwater processes such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording devices (USR) were built to monitor the acoustic sound pressure waves generated by those anthropogenic underwater activities, so the relevant processing software becomes indispensable for analyzing the audio files recorded by these USRs. However, existing software packages did not meet performance and flexibility requirements. In this paper, we provide a detailed description of a new software package, named Aquatic Acoustic Metrics Interface (AAMI), which is a Graphicalmore » User Interface (GUI) designed for underwater sound monitoring and analysis. In addition to the general functions, such as loading and editing audio files recorded by USRs, the software can compute a series of acoustic metrics in physical units, monitor the sound's influence on fish hearing according to audiograms from different species of fishes and marine mammals, and batch process the sound files. The detailed applications of the software AAMI will be discussed along with several test case scenarios to illustrate its functionality.« less

Research on the Effect of Welding Speed on the Quality of Welding Seam Based on the Local Dry Underwater Welding

NASA Astrophysics Data System (ADS)

Liu, Lei; Chen, Wu; Wang, Huagang; Ba, Jinyu; Li, Bing

2017-12-01

The repair of nuclear spent fuel pool has a high requirement for the quality of welding, the welding speed directly affects the quality of the weld when local dry automatic underwater welding is used to repair the damaged surface. Under the condition of the same condition, the local dry automatic underwater welding test was carried out under the condition of the same welding condition. Taking the 20cm as the experimental condition, after massive experiments show that when the welding speed is approximately 48cm/min the weld quality is high, meeting the design requirements, based on the double layer shrinkage nozzle chamber of local dry underwater automatic welding.

A comparison of underwater hearing sensitivity in bottlenose dolphins (Tursiops truncatus) determined by electrophysiological and behavioral methods.

PubMed

Houser, Dorian S; Finneran, James J

2006-09-01

Variable stimulus presentation methods are used in auditory evoked potential (AEP) estimates of cetacean hearing sensitivity, each of which might affect stimulus reception and hearing threshold estimates. This study quantifies differences in underwater hearing thresholds obtained by AEP and behavioral means. For AEP estimates, a transducer embedded in a suction cup (jawphone) was coupled to the dolphin's lower jaw for stimulus presentation. Underwater AEP thresholds were obtained for three dolphins in San Diego Bay and for one dolphin in a quiet pool. Thresholds were estimated from the envelope following response at carrier frequencies ranging from 10 to 150 kHz. One animal, with an atypical audiogram, demonstrated significantly greater hearing loss in the right ear than in the left. Across test conditions, the range and average difference between AEP and behavioral threshold estimates were consistent with published comparisons between underwater behavioral and in-air AEP thresholds. AEP thresholds for one animal obtained in-air and in a quiet pool demonstrated a range of differences of -10 to 9 dB (mean = 3 dB). Results suggest that for the frequencies tested, the presentation of sound stimuli through a jawphone, underwater and in-air, results in acceptable differences to AEP threshold estimates.

Unmanned Instrument Platform for Undersea Exploration

NASA Technical Reports Server (NTRS)

Paine, G.; Hansen, G. R.; Gulizia, R. W.; Paluzzi, P.

1984-01-01

Instruments accommodated on moving underwater platform. Towable underwater platform 3.2 meters long, 1.2 meters wide, 1.4 meters high and has mass of about 1,250 kilogram. Platform remotely operated and unmanned. Serves as test bed for development of ocean-measuring instruments and sonars at depths to 20,000 feet.

Using Underwater Explosion and Cylinder Expansion Tests to Calibrate Afterburn Models for Aluminized Explosives

NASA Astrophysics Data System (ADS)

Wedberg, Rasmus

2017-06-01

The study explores the combined use of underwater performance tests and cylinder expansion tests in order to parameterize detonation models for aluminized explosives which exhibit afterburning. The approach is suggested to be used in conjunction with thermochemical computation. A formulation containing RDX and aluminum powder is considered and several charges with varying masses are submerged and detonated. Pressure gauges are employed at horizontal distances scaling with the charge diameter, and the specific shock wave energy is shown to increase with charge mass. This is attributed to the combustion of aluminum particles after the Chapman-Jouguet plane. Cylinder expansion tests are carried out using Photon Doppler Velocimetry to register the wall expansion velocity. The tests are modeled using a multi-material arbitrary Lagrangian-Eulerian approach with the Guirguis-Miller model describing detonation with afterburning. The equation of state and afterburn rate law parameters are adjusted such that the model reproduces the results from the cylinder expansion and underwater tests. The approach seems promising, and might be valuable for aluminized explosive formulations intended to be used in a variety of confinement conditions. Swedish Armed Forces.

Experimental Investigations of the Effects of Underwater Explosions on Swimbladder Fish, II: 1975 Chesapeake Bay Tests

DTIC Science & Technology

1976-09-21

Ranges Environmental Effects of Explosions 20. ABSTRACT (Continue on reverse side It necessary and Identify by block number; The experiment...CHESAPEAKE BAY TESTS The Navy is required to consider the possible adverse environmental effects of its research operations. When such operations involve...the detonation of underwater explosions, one of the environmental factors to be evaluated is the effect of these explosions on nearby marine life

Underwater temporary threshold shift induced by octave-band noise in three species of pinniped.

PubMed

Kastak, D; Schusterman, R J; Southall, B L; Reichmuth, C J

1999-08-01

Pure-tone sound detection thresholds were obtained in water for one harbor seal (Phoca vitulina), two California sea lions (Zalophus californianus), and one northern elephant seal (Mirounga angustirostris) before and immediately following exposure to octave-band noise. Additional thresholds were obtained following a 24-h recovery period. Test frequencies ranged from 100 Hz to 2000 Hz and octave-band exposure levels were approximately 60-75 dB SL (sensation level at center frequency). Each subject was trained to dive into a noise field and remain stationed underwater during a noise-exposure period that lasted a total of 20-22 min. Following exposure, three of the subjects showed threshold shifts averaging 4.8 dB (Phoca), 4.9 dB (Zalophus), and 4.6 dB (Mirounga). Recovery to baseline threshold levels was observed in test sessions conducted within 24 h of noise exposure. Control sessions in which the subjects completed a simulated noise exposure produced shifts that were significantly smaller than those observed following noise exposure. These results indicate that noise of moderate intensity and duration is sufficient to induce TTS under water in these pinniped species.

An IMM-Aided ZUPT Methodology for an INS/DVL Integrated Navigation System.

PubMed

Yao, Yiqing; Xu, Xiaosu; Xu, Xiang

2017-09-05

Inertial navigation system (INS)/Doppler velocity log (DVL) integration is the most common navigation solution for underwater vehicles. Due to the complex underwater environment, the velocity information provided by DVL always contains some errors. To improve navigation accuracy, zero velocity update (ZUPT) technology is considered, which is an effective algorithm for land vehicles to mitigate the navigation error during the pure INS mode. However, in contrast to ground vehicles, the ZUPT solution cannot be used directly for underwater vehicles because of the existence of the water current. In order to leverage the strengths of the ZUPT method and the INS/DVL solution, an interactive multiple model (IMM)-aided ZUPT methodology for the INS/DVL-integrated underwater navigation system is proposed. Both the INS/DVL and INS/ZUPT models are constructed and operated in parallel, with weights calculated according to their innovations and innovation covariance matrices. Simulations are conducted to evaluate the proposed algorithm. The results indicate that the IMM-aided ZUPT solution outperforms both the INS/DVL solution and the INS/ZUPT solution in the underwater environment, which can properly distinguish between the ZUPT and non-ZUPT conditions. In addition, during DVL outage, the effectiveness of the proposed algorithm is also verified.

Synthesis and Development of Gold Polypyrrole Actuator for Underwater Application

NASA Astrophysics Data System (ADS)

Panda, S. K.; Bandopadhya, D.

2018-02-01

Electro-active polymer (EAP) such as Polypyrrole has gained much attention in the category of functional materials for fabrication of both active actuator and sensor. Particularly, PPy actuator has shown potential in fluid medium application because of high strain, large bending displacement and work density. This paper focuses on developing a low cost active actuator promising in delivering high performance in underwater environment. The proposed Au-pyrrole actuator is synthesized by adopting the layer-by-layer electrochemical polymerization technique and is fabricated as strip actuator from aqueous solution of Pyrrole and NaDBS in room temperature. In the follow-up, topographical analysis has been carried out using SEM and FESEM instruments showing surface morphology and surface integrity of chemical components of the structure. Several experiments have been conducted under DC input voltage evaluating performance effectiveness such as underwater bending displacement and tip force etc. This is observed that the actuator exhibits quite similar stress profile as of natural muscle, endowed with high modulus makes them effective in working nearly 10,000 cycles underwater environment. In addition, the bending displacement up to 5.4 mm with a low input voltage 1.3 V makes the actuator suitable for underwater micro-robotics applications.

Electrically-Conductive Polyaramid Cable And Fabric

NASA Technical Reports Server (NTRS)

Orban, Ralph F.

1988-01-01

Tows coated with metal provide strength and conductance. Cable suitable for use underwater made of electrically conductive tows of metal-coated polyaramid filaments surrounded by electrically insulating jacket. Conductive tows used to make conductive fabrics. Tension borne by metal-coated filaments, so upon release, entire cable springs back to nearly original length without damage.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin monitor some of the project's equipment just released into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin monitor some of the project's equipment just released into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Justin Manley, of the National Oceanic and Atmospheric Administration, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Justin Manley, of the National Oceanic and Atmospheric Administration, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin retrieve some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin retrieve some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin lifts some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin lifts some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin releases some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin releases some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepare to release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepare to release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin secure some of the project's equipment back into the vessel. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin secure some of the project's equipment back into the vessel. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepares some of the project's equipment for placement in the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepares some of the project's equipment for placement in the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge as others stand by in a watercraft during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge as others stand by in a watercraft during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

Analysis of Water Shock Data and Bubble Screen Effectiveness on the Blast Effect Mitigation Test Series, Wilmington Harbor, North Carolina

DTIC Science & Technology

2000-08-01

ERDC/SL ; TR-00-4) Includes bibliographic references. 1. Underwater explosions - Testing. 2. Shock waves. 3. Air curtains. 4. Wilmington, (N.C...water is the placement of air curtains or bubble screens around the underwater explosive source. Bubble screens are generated by pumping air into a...Geomechanics and Explosion Effects Division (GEED), Structures Laboratory (SL), Waterways Experiment Station (WES), U. S. Army Engineer Research and

A Chemical Monitoring Program of the Explosion Products in Underwater Explosion Tests

DTIC Science & Technology

1975-04-04

CLASSIFICATION QF THIS PAGE- (When Date Entered) UNCLASSIFIED tL,URJTY CLASSIFICATION OF THIS PAGE(Then Data Entered) 20.and determination of various explosion...to institute a chemical monitoring program of the explosion products in underwater explosion tests, to determine monitoring parameters, and to...27 3.2.3 Samplers 28 3.2.4 Storage of Sediment Samples 32 IV. DETERMINATION OF EXPLOSION PRODUCTS 32 4.1 DESIGN OF MEASUREMENT SYSTEM 32 4.1.1

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

Motion analysis and trials of the deep sea hybrid underwater glider Petrel-II

NASA Astrophysics Data System (ADS)

Liu, Fang; Wang, Yan-hui; Wu, Zhi-liang; Wang, Shu-xin

2017-03-01

A hybrid underwater glider Petrel-II has been developed and field tested. It is equipped with an active buoyancy unit and a compact propeller unit. Its working modes have been expanded to buoyancy driven gliding and propeller driven level-flight, which can make the glider work in strong currents, as well as many other complicated ocean environments. Its maximal gliding speed reaches 1 knot and the propelling speed is up to 3 knots. In this paper, a 3D dynamic model of Petrel-II is derived using linear momentum and angular momentum equations. According to the dynamic model, the spiral motion in the underwater space is simulated for the gliding mode. Similarly the cycle motion on water surface and the depth-keeping motion underwater are simulated for the level-flight mode. These simulations are important to the performance analysis and parameter optimization for the Petrel-II underwater glider. The simulation results show a good agreement with field trials.

Preparation of Polyurethane/Graphite Composite Films with Stable Mechanical Property and Wear Resistance Underwater.

PubMed

Wang, Miaomiao; Wang, Zubin; Chen, Qirong; Meng, Xiangfu; Heng, Liping

2018-06-01

The wear resistance and stable mechanical properties affect the service life of the underwater functional materials to a certain extent. Unfortunately, the current study of underwater functional materials is rarely related to these aspects. Herein, we successfully designed and prepared polyurethane/graphite nanosheet (PU/GN) composite materials, which exhibited excellent wear resistance and stable mechanical properties underwater. The PU/GN composite films were prepared by evaporating a mixed solution of PU and GN on concave hexagonal honeycomb silicon templates. The mechanical properties of the composite films were determined by tensile test, and the wear resistance was evaluated by comparing the surface morphology before and after grind. By adjusting the content of graphite in the composite films, we found that the composite films containing 23 wt% GN had higher tensile strength and superior wear resistance. Moreover, this composite film showed an outstanding stability when expose to water. The impressive results along with simple preparation process made PU/GN composite films had potential applications in robust underwater functional materials.

Subjective Quality Assessment of Underwater Video for Scientific Applications

PubMed Central

Moreno-Roldán, José-Miguel; Luque-Nieto, Miguel-Ángel; Poncela, Javier; Díaz-del-Río, Víctor; Otero, Pablo

2015-01-01

Underwater video services could be a key application in the better scientific knowledge of the vast oceanic resources in our planet. However, limitations in the capacity of current available technology for underwater networks (UWSNs) raise the question of the feasibility of these services. When transmitting video, the main constraints are the limited bandwidth and the high propagation delays. At the same time the service performance depends on the needs of the target group. This paper considers the problems of estimations for the Mean Opinion Score (a standard quality measure) in UWSNs based on objective methods and addresses the topic of quality assessment in potential underwater video services from a subjective point of view. The experimental design and the results of a test planned according standardized psychometric methods are presented. The subjects used in the quality assessment test were ocean scientists. Video sequences were recorded in actual exploration expeditions and were processed to simulate conditions similar to those that might be found in UWSNs. Our experimental results show how videos are considered to be useful for scientific purposes even in very low bitrate conditions. PMID:26694400

Subjective Quality Assessment of Underwater Video for Scientific Applications.

PubMed

Moreno-Roldán, José-Miguel; Luque-Nieto, Miguel-Ángel; Poncela, Javier; Díaz-del-Río, Víctor; Otero, Pablo

2015-12-15

Underwater video services could be a key application in the better scientific knowledge of the vast oceanic resources in our planet. However, limitations in the capacity of current available technology for underwater networks (UWSNs) raise the question of the feasibility of these services. When transmitting video, the main constraints are the limited bandwidth and the high propagation delays. At the same time the service performance depends on the needs of the target group. This paper considers the problems of estimations for the Mean Opinion Score (a standard quality measure) in UWSNs based on objective methods and addresses the topic of quality assessment in potential underwater video services from a subjective point of view. The experimental design and the results of a test planned according standardized psychometric methods are presented. The subjects used in the quality assessment test were ocean scientists. Video sequences were recorded in actual exploration expeditions and were processed to simulate conditions similar to those that might be found in UWSNs. Our experimental results show how videos are considered to be useful for scientific purposes even in very low bitrate conditions.

Underwater detection by using ultrasonic sensor

NASA Astrophysics Data System (ADS)

Bakar, S. A. A.; Ong, N. R.; Aziz, M. H. A.; Alcain, J. B.; Haimi, W. M. W. N.; Sauli, Z.

2017-09-01

This paper described the low cost implementation of hardware and software in developing the system of ultrasonic which can visualize the feedback of sound in the form of measured distance through mobile phone and monitoring the frequency of detection by using real time graph of Java application. A single waterproof transducer of JSN-SR04T had been used to determine the distance of an object based on operation of the classic pulse echo detection method underwater. In this experiment, the system was tested by placing the housing which consisted of Arduino UNO, Bluetooth module of HC-06, ultrasonic sensor and LEDs at the top of the box and the transducer was immersed in the water. The system which had been tested for detection in vertical form was found to be capable of reporting through the use of colored LEDs as indicator to the relative proximity of object distance underwater form the sensor. As a conclusion, the system can detect the presence of an object underwater within the range of ultrasonic sensor and display the measured distance onto the mobile phone and the real time graph had been successfully generated.

Optical aberrations in underwater photogrammetry with flat and hemispherical dome ports

NASA Astrophysics Data System (ADS)

Menna, Fabio; Nocerino, Erica; Remondino, Fabio

2017-06-01

The paper analyses differences between dome and flat port housings used for underwater photogrammetry. The underwater environment negatively affects image quality and 3D reconstructions, but this influence on photogrammetric measurements, so far, has not been addressed properly in the literature. In this work, motivations behind the need for systematic underwater calibrations are provided, then experimental tests using a specifically designed photogrammetric modular test object in laboratory and at sea are reported. The experiments are carried out using a Nikon D750 24 Mpx DSLR camera with a 24 mm f2.8 AF/D lens coupled with a NIMAR NI3D750ZM housing, equipped first with a dome and, successively, with a flat port. To quantify the degradation of image quality, MTF measurements are carried out, then the outcomes of self-calibrating bundle adjustment calibrations are shown and commented. Optical phenomena like field curvature as well as chromatic aberration and astigmatism are analysed and their implications on the degradation of image quality is factored in the bundle adjustment through a different weighting of 2D image observations.

Experiences from using Autonomous Underwater Vehicles and Synthetic Aperture Sonar for Sediment and Habitat Mapping

NASA Astrophysics Data System (ADS)

Thorsnes, T.; Bjarnadóttir, L. R.

2017-12-01

Emerging platforms and tools like autonomous underwater vehicles and synthetic aperture sonars provide interesting opportunities for making seabed mapping more efficient and precise. Sediment grain-size maps are an important product in their own right and a key input for habitat and biotope maps. National and regional mapping programmes are tasked with mapping large areas, and survey efficiency, data quality, and resulting map confidence are important considerations when selecting the mapping strategy. Since 2005, c. 175,000 square kilometres of the Norwegian continental shelf and continental slope has been mapped with respect to sediments, habitats and biodiversity, and pollution under the MAREANO programme (www.mareano.no). At present the sediment mapping is based on a combination of ship-borne multibeam bathymetry and backscatter, visual documentation using a towed video platform, and grab sampling. We have now tested a new approach, using an Autonomous Underwater Vehicle (AUV) as the survey platform for the collection of acoustic data (Synthetic Aperture Sonar (SAS), EM2040 bathymetry and backscatter) and visual data (still images using a TFish colour photo system). This pilot project was conducted together the Norwegian Hydrographic Service, the Institute of Marine Research (biology observations) and the Norwegian Defence Research Establishment (operation of ship and AUV). The test site reported here is the Vesterdjupet area, offshore Lofoten, northern Norway. The water depth is between 170 and 300 metres, with sediments ranging from gravel, cobbles and boulders to sandy mud. A cold-water coral reef, associated with bioclastic sediments was also present in the study area. The presentation will give an overview of the main findings and experiences gained from this pilot project with a focus on geological mapping and will also discuss the relevance of AUV-based mapping to large-area mapping programmes like MAREANO.

A facile bacterial assisted electrochemical self-assembly of polypyrrole micro-pillars: towards underwater low adhesive superoleophobicity

NASA Astrophysics Data System (ADS)

Cheng, Zhe; Ding, Chunmei; Liu, Huan; Zhu, Ying; Jiang, Lei

2013-12-01

By taking advantage of bacterial extracellular electron transfer behavior, a facile method was developed to fabricate oriented polypyrrole micro-pillars (PPy-MP) with nanoscale surface roughness. Microbes acted as a living conductive template on which PPy was in situ polymerized. The as-prepared PPy-MP exhibit the distinctive underwater low adhesive superoleophobicity which is attributable to the unique hierarchical micro/nano-structures and the high surface energy by doping with inorganic small anions.By taking advantage of bacterial extracellular electron transfer behavior, a facile method was developed to fabricate oriented polypyrrole micro-pillars (PPy-MP) with nanoscale surface roughness. Microbes acted as a living conductive template on which PPy was in situ polymerized. The as-prepared PPy-MP exhibit the distinctive underwater low adhesive superoleophobicity which is attributable to the unique hierarchical micro/nano-structures and the high surface energy by doping with inorganic small anions. Electronic supplementary information (ESI) available: The shape of a water drop on PPy-MPA and cauliflower-like PPy film in air. See DOI: 10.1039/c3nr03788f

Underwater Sediment Sampling Research

DTIC Science & Technology

2017-01-01

resolved through further experimentation . Underwater Sediment Sampling Research vi UNCLAS//Public | CG-926 RDC | A. Hanson, et al. Public...Chemical Oceanographer, and In situ Chemical Analysis Subject Matter Expert (SME). 2 LABORATORY TEST SET UP The experimental research and laboratory... methodology involved using a fluorescence oil sensor (Turner Designs Cyclops-7) to measure the TPH contained in the interstitial waters (i.e., pore

A Novel Method to Determine the Hydrodynamic Coefficients of an Eyeball ROV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yh, Eng; Ws, Lau; Low, E.

2009-01-12

A good dynamics model is essential and critical for the successful design of navigation and control system of an underwater vehicle. However, it is difficult to determine from the hydrodynamic forces, the inertial added mass terms and the drag coefficients. In this paper, a new experimental method has been used to find the hydrodynamic forces for the ROV II, a remotely operated underwater vehicle. The proposed method is based on the classical free decay test, but with the spring oscillation replaced by a pendulum motion. The experiment results determined from the free decay test of a scaled model compared wellmore » with the simulation results obtained from well‐established computational fluid dynamics (CFD) program. Thus, the proposed approach can be used to find the added mass and drag coefficients for other underwater vehicles.« less

Bathymetric and underwater video survey of Lower Granite Reservoir and vicinity, Washington and Idaho, 2009-10

USGS Publications Warehouse

Williams, Marshall L.; Fosness, Ryan L.; Weakland, Rhonda J.

2012-01-01

The U.S. Geological Survey conducted a bathymetric survey of the Lower Granite Reservoir, Washington, using a multibeam echosounder, and an underwater video mapping survey during autumn 2009 and winter 2010. The surveys were conducted as part of the U.S. Army Corps of Engineer's study on sediment deposition and control in the reservoir. The multibeam echosounder survey was performed in 1-mile increments between river mile (RM) 130 and 142 on the Snake River, and between RM 0 and 2 on the Clearwater River. The result of the survey is a digital elevation dataset in ASCII coordinate positioning data (easting, northing, and elevation) useful in rendering a 3×3-foot point grid showing bed elevation and reservoir geomorphology. The underwater video mapping survey was conducted from RM 107.73 to 141.78 on the Snake River and RM 0 to 1.66 on the Clearwater River, along 61 U.S. Army Corps of Engineers established cross sections, and dredge material deposit transects. More than 900 videos and 90 bank photographs were used to characterize the sediment facies and ground-truth the multibeam echosounder data. Combined, the surveys were used to create a surficial sediment facies map that displays type of substrate, level of embeddedness, and presence of silt.

Operation and testing of Mark 10 Mod 3 underwater breathing apparatus

NASA Technical Reports Server (NTRS)

Milwee, W. I., Jr.

1972-01-01

Performance tests on a closed circuit, mixed gas underwater breathing apparatus are reported. The equipment is designed to provide a minimum diving duration of four hours at 1500 ft below sea surface; it senses oxygen partial pressure in the breathing gas mix and controls oxygen content of the breathing gas within narrow limits about a preset value. The breathing circuit subsystem provides respirable gas to the diver and removes carbon dioxide and moisture from the expired gas. Test results indicate undesirable variations in oxygen partial pressure with oxygen addition and insufficient carbon dioxide absorption.

Underwater videography outperforms above-water videography and in-person surveys for monitoring the spawning of Devils Hole Pupfish

USGS Publications Warehouse

Chaudoin, Ambre L.; Feuerbacher, Olin; Bonar, Scott A.; Barrett, Paul J.

2015-01-01

The monitoring of threatened and endangered fishes in remote environments continues to challenge fisheries biologists. The endangered Devils Hole Pupfish Cyprinodon diabolis, which is confined to a single warm spring in Death Valley National Park, California–Nevada, has recently experienced record declines, spurring renewed conservation and recovery efforts. In February–December 2010, we investigated the timing and frequency of spawning in the species' native habitat by using three survey methods: underwater videography, above-water videography, and in-person surveys. Videography methods incorporated fixed-position, solar-powered cameras to record continuous footage of a shallow rock shelf that Devils Hole Pupfish use for spawning. In-person surveys were conducted from a platform placed above the water's surface. The underwater camera recorded more overall spawning throughout the year (mean ± SE = 0.35 ± 0.06 events/sample) than the above-water camera (0.11 ± 0.03 events/sample). Underwater videography also recorded more peak-season spawning (March: 0.83 ± 0.18 events/sample; April: 2.39 ± 0.47 events/sample) than above-water videography (March: 0.21 ± 0.10 events/sample; April: 0.9 ± 0.32 events/sample). Although the overall number of spawning events per sample did not differ significantly between underwater videography and in-person surveys, underwater videography provided a larger data set with much less variability than data from in-person surveys. Fixed videography was more cost efficient than in-person surveys (\\$1.31 versus \\$605 per collected data-hour), and underwater videography provided more usable data than above-water videography. Furthermore, video data collection was possible even under adverse conditions, such as the extreme temperatures of the region, and could be maintained successfully with few study site visits. Our results suggest that self-contained underwater cameras can be efficient tools for monitoring remote and sensitive aquatic ecosystems.

Underwater image enhancement based on the dark channel prior and attenuation compensation

NASA Astrophysics Data System (ADS)

Guo, Qingwen; Xue, Lulu; Tang, Ruichun; Guo, Lingrui

2017-10-01

Aimed at the two problems of underwater imaging, fog effect and color cast, an Improved Segmentation Dark Channel Prior (ISDCP) defogging method is proposed to solve the fog effects caused by physical properties of water. Due to mass refraction of light in the process of underwater imaging, fog effects would lead to image blurring. And color cast is closely related to different degree of attenuation while light with different wavelengths is traveling in water. The proposed method here integrates the ISDCP and quantitative histogram stretching techniques into the image enhancement procedure. Firstly, the threshold value is set during the refinement process of the transmission maps to identify the original mismatching, and to conduct the differentiated defogging process further. Secondly, a method of judging the propagating distance of light is adopted to get the attenuation degree of energy during the propagation underwater. Finally, the image histogram is stretched quantitatively in Red-Green-Blue channel respectively according to the degree of attenuation in each color channel. The proposed method ISDCP can reduce the computational complexity and improve the efficiency in terms of defogging effect to meet the real-time requirements. Qualitative and quantitative comparison for several different underwater scenes reveals that the proposed method can significantly improve the visibility compared with previous methods.

An IMM-Aided ZUPT Methodology for an INS/DVL Integrated Navigation System

PubMed Central

Yao, Yiqing

2017-01-01

Inertial navigation system (INS)/Doppler velocity log (DVL) integration is the most common navigation solution for underwater vehicles. Due to the complex underwater environment, the velocity information provided by DVL always contains some errors. To improve navigation accuracy, zero velocity update (ZUPT) technology is considered, which is an effective algorithm for land vehicles to mitigate the navigation error during the pure INS mode. However, in contrast to ground vehicles, the ZUPT solution cannot be used directly for underwater vehicles because of the existence of the water current. In order to leverage the strengths of the ZUPT method and the INS/DVL solution, an interactive multiple model (IMM)-aided ZUPT methodology for the INS/DVL-integrated underwater navigation system is proposed. Both the INS/DVL and INS/ZUPT models are constructed and operated in parallel, with weights calculated according to their innovations and innovation covariance matrices. Simulations are conducted to evaluate the proposed algorithm. The results indicate that the IMM-aided ZUPT solution outperforms both the INS/DVL solution and the INS/ZUPT solution in the underwater environment, which can properly distinguish between the ZUPT and non-ZUPT conditions. In addition, during DVL outage, the effectiveness of the proposed algorithm is also verified. PMID:28872602

Captive Bottlenose Dolphins Do Discriminate Human-Made Sounds Both Underwater and in the Air.

PubMed

Lima, Alice; Sébilleau, Mélissa; Boye, Martin; Durand, Candice; Hausberger, Martine; Lemasson, Alban

2018-01-01

Bottlenose dolphins ( Tursiops truncatus ) spontaneously emit individual acoustic signals that identify them to group members. We tested whether these cetaceans could learn artificial individual sound cues played underwater and whether they would generalize this learning to airborne sounds. Dolphins are thought to perceive only underwater sounds and their training depends largely on visual signals. We investigated the behavioral responses of seven dolphins in a group to learned human-made individual sound cues, played underwater and in the air. Dolphins recognized their own sound cue after hearing it underwater as they immediately moved toward the source, whereas when it was airborne they gazed more at the source of their own sound cue but did not approach it. We hypothesize that they perhaps detected modifications of the sound induced by air or were confused by the novelty of the situation, but nevertheless recognized they were being "targeted." They did not respond when hearing another group member's cue in either situation. This study provides further evidence that dolphins respond to individual-specific sounds and that these marine mammals possess some capacity for processing airborne acoustic signals.

Dolphin Sounds-Inspired Covert Underwater Acoustic Communication and Micro-Modem

PubMed Central

Qiao, Gang; Liu, Songzuo; Bilal, Muhammad

2017-01-01

A novel portable underwater acoustic modem is proposed in this paper for covert communication between divers or underwater unmanned vehicles (UUVs) and divers at a short distance. For the first time, real dolphin calls are used in the modem to realize biologically inspired Covert Underwater Acoustic Communication (CUAC). A variety of dolphin whistles and clicks stored in an SD card inside the modem helps to realize different biomimetic CUAC algorithms based on the specified covert scenario. In this paper, the information is conveyed during the time interval between dolphin clicks. TMS320C6748 and TLV320AIC3106 are the core processors used in our unique modem for fast digital processing and interconnection with other terminals or sensors. Simulation results show that the bit error rate (BER) of the CUAC algorithm is less than 10−5 when the signal to noise ratio is over ‒5 dB. The modem was tested in an underwater pool, and a data rate of 27.1 bits per second at a distance of 10 m was achieved. PMID:29068363

Assessment of laser tracking and data transfer for underwater optical communications

NASA Astrophysics Data System (ADS)

Watson, Malcolm A.; Blanchard, Paul M.; Stace, Chris; Bhogul, Priya K.; White, Henry J.; Kelly, Anthony E.; Watson, Scott; Valyrakis, Manousos; Najda, Stephen P.; Marona, Lucja; Perlin, Piotr

2014-10-01

We report on an investigation into optical alignment and tracking for high bandwidth, laser-based underwater optical communication links. Link acquisition approaches (including scanning of narrow laser beams versus a wide-angle `beacon' approach) for different underwater laser-based communications scenarios are discussed. An underwater laserbased tracking system was tested in a large water flume facility using water whose scattering properties resembled that of a turbid coastal or harbour region. The lasers used were state-of-the-art, temperature-controlled, high modulation bandwidth gallium nitride (GaN) devices. These operate at blue wavelengths and can achieve powers up to ~100 mW. The tracking performance and characteristics of the system were studied as the light-scattering properties of the water were increased using commercial antacid (Maalox) solution, and the results are reported here. Optical tracking is expected to be possible even in high scattering water environments, assuming better components are developed commercially; in particular, more sensitive detector arrays. High speed data transmission using underwater optical links, based on blue light sources, is also reported.

Comparison of Effects of a Proprioceptive Exercise Program in Water and on Land the Balance of Chronic Stroke Patients

PubMed Central

Han, Seul Ki; Kim, Myung Chul; An, Chang Sik

2013-01-01

[Purpose] The purpose of this study was to compare changes in balance ability of land exercise and underwater exercise on chronic stroke patients. [Subjects] A total of 60 patients received exercise for 40 minutes, three times a week, for 6 weeks. [Methods] Subjects from both groups performed general conventional treatment during the experimental period. In addition, all subjects engaged in extra treatment sessions. This extra treatment consisted of unstable surface exercise. The underwater exercise group used wonder boards in a pool (depth 1.1m, water temperature 33.5 °C, air temperature 27 °C) dedicated to underwater exercise, and the land exercise group used balance mats. [Result] The joint position sense, sway area, Berg Balance Scale showed significant improvements in both groups. However, the joint position sense test, sway area, and Berg Balance Scale showed there was more improvement in the underwater exercise group than in the land exercise group. [Conclusion] The results suggest that underwater exercise is more effective than land exercise at improving the joint position sense and balance of stroke patients. PMID:24259761

Comparison of effects of a proprioceptive exercise program in water and on land the balance of chronic stroke patients.

PubMed

Han, Seul Ki; Kim, Myung Chul; An, Chang Sik

2013-10-01

[Purpose] The purpose of this study was to compare changes in balance ability of land exercise and underwater exercise on chronic stroke patients. [Subjects] A total of 60 patients received exercise for 40 minutes, three times a week, for 6 weeks. [Methods] Subjects from both groups performed general conventional treatment during the experimental period. In addition, all subjects engaged in extra treatment sessions. This extra treatment consisted of unstable surface exercise. The underwater exercise group used wonder boards in a pool (depth 1.1m, water temperature 33.5 °C, air temperature 27 °C) dedicated to underwater exercise, and the land exercise group used balance mats. [Result] The joint position sense, sway area, Berg Balance Scale showed significant improvements in both groups. However, the joint position sense test, sway area, and Berg Balance Scale showed there was more improvement in the underwater exercise group than in the land exercise group. [Conclusion] The results suggest that underwater exercise is more effective than land exercise at improving the joint position sense and balance of stroke patients.

Modular detector for deep underwater registration of muons and muon groups

NASA Technical Reports Server (NTRS)

Demianov, A. I.; Sarycheva, L. I.; Sinyov, N. B.; Varadanyan, I. N.; Yershov, A. A.

1985-01-01

Registration and identification of muons and muon groups penetrating into the ocean depth, can be performed using a modular multilayer detector with high resolution bidimensional readout - deep underwater calorimeter (project NADIR). Laboratory testing of a prototype sensor cell with liquid scintillator in light-tight casing, testifies to the practicability of the full-scale experiment within reasonable expences.

Biosensor UUV payload for underwater detection

NASA Astrophysics Data System (ADS)

Kusterbeck, Anne W.; Charles, Paul T.; Melde, Brian J.; Trammell, Scott A.; Adams, André A.; Deschamps, Jeffrey R.

2010-04-01

Increased emphasis on maritime domain awareness and port security has led to the development of unmanned underwater vehicles (UUVs) capable of extended missions. These systems rely most frequently on well-developed side scan sonar and acoustic methods to locate potential targets. The Naval Research Laboratory (NRL) is developing biosensors for underwater explosives detection that complement acoustic sensors and can be used as UUV payloads to monitor areas for port and harbor security or in detection of underwater unexploded ordnance (UXO) and biochemical threats. The prototype sensor has recently been demonstrated to detect explosives in seawater at trace levels when run in a continuous sampling mode. To overcome ongoing issues with sample preparation and facilitate rapid detection at trace levels in a marine environment, we have been developing new mesoporous materials for in-line preconcentration of explosives and other small molecules, engineering microfluidic components to improve the signal, and testing alternative signal transduction methods. Additional work is being done to optimize the optical components and sensor response time. Highlights of these current studies and our ongoing efforts to integrate the biosensor with existing detection technologies to reduce false positives are described. In addition, we present the results of field tests that demonstrate the prototype biosensor performance as a UUV payload.

Underwater partial polarization signatures from the shallow water real-time imaging polarimeter (SHRIMP)

NASA Astrophysics Data System (ADS)

Taylor, James S., Jr.; Davis, P. S.; Wolff, Lawrence B.

2003-09-01

Research has shown that naturally occurring light outdoors and underwater is partially linearly polarized. The polarized components can be combined to form an image that describes the polarization of the light in the scene. This image is known as the degree of linear polarization (DOLP) image or partial polarization image. These naturally occurring polarization signatures can provide a diver or an unmanned underwater vehicle (UUV) with more information to detect, classify, and identify threats such as obstacles and/or mines in the shallow water environment. The SHallow water Real-time IMaging Polarimeter (SHRIMP), recently developed under sponsorship of Dr. Tom Swean at the Office of Naval Research (Code 321OE), can measure underwater partial polarization imagery. This sensor is a passive, three-channel device that simultaneously measures the three components of the Stokes vector needed to determine the partial linear polarization of the scene. The testing of this sensor has been completed and the data has been analyzed. This paper presents performance results from the field-testing and quantifies the gain provided by the partial polarization signature of targets in the Very Shallow Water (VSW) and Surf Zone (SZ) regions.

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.

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.

Underwater olfaction for real-time detection of submerged unexploded ordnance

NASA Astrophysics Data System (ADS)

Harper, Ross J.; Dock, Matthew L.

2007-04-01

The presence of Underwater Unexploded Ordnance (UUXO) represents a considerable threat in the marine environment. Elevated concentrations of dissolved explosive compounds, such as TNT and RDX, may be produced in the vicinity of degraded UUXO shell casings and are known to have significant toxicant effects on local marine organisms. During World War II and in subsequent years, the US military inadvertently or, in some cases intentionally, deposited many thousands of tons of UUXO in US coastal waters. Much of this material is difficult to locate by magnetometry or sonar imaging techniques, and can be extremely challenging to identify by visual means after lying on the bottom of the ocean for several decades. The present work is focused on advances in underwater olfaction, wherein trace amounts of dissolved explosive compounds may be detected and discriminated from other chemical species found in the marine environment, for the purpose of establishing safe cordons and/or neutralization of the explosives. ICx Nomadics has developed the first known real-time sensor system that is capable of detecting chemical signatures emanating from underwater explosives. The SeaPup sensor, which is based on the fluorescence-quenching transduction mechanism of an amplifying fluorescent polymer (AFP), is capable of real-time detection of the trace chemical signatures emanating from submerged explosive compounds. The SeaPup system has been successfully tested on various marine platforms, including a crawler robot, an autonomous underwater vehicle (AUV), and a remotely operated underwater vehicle (ROV). In one study, the SeaPup was shown to effectively map liquid phase "explosive scent plumes" emanating from an underwater source of TNT. The presented paper will provide an overview of the history, current status, and future development of explosive analyte detection in the underwater environment.

Extended Range Underwater Loudhailer for Port Security Applications

DTIC Science & Technology

2006-06-01

and Subtitle Extended Range Underwater Loudhailer for Port Security Applications 6. Performing Organization Code Project No. 5903 7. Author( s ...used in the audio market . The name ‘RCA’ derives from the Radio Corporation of America, which introduced the design, by the early 1940s, to allow...Test June 2005 Test Range (yds) S pe ct ru m B an d Le ve l ( dB re 1 µ P a) S pe ct ru m B an d Le ve l ( dB re 1 µ P a) Figure 9

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.

Effect of Traverse and Rotational Speeds on the Tensile Behavior of the Underwater Dissimilar Friction Stir Welded Aluminum Alloys

NASA Astrophysics Data System (ADS)

Bijanrostami, Kh.; Barenji, R. Vatankhah; Hashemipour, M.

2017-02-01

The tensile behavior of the underwater dissimilar friction stir welded AA6061 and AA7075 aluminum alloy joints was investigated for the first time. For this aim, the joints were welded at different conditions and tensile test was conducted for measuring the strength and elongation of them. In addition, the microstructure of the joints was characterized by means of optical and transmission electron microscopes. Scanning electron microscope was used for fractography of the joints. Furthermore, the process parameters and tensile properties of the joints were correlated and optimized. The results revealed that the maximum tensile strength of 237.3 MPa and elongation of 41.2% could be obtained at a rotational speed 1853 rpm and a traverse speed of 50 mm/min. In comparison with the optimum condition, higher heat inputs caused grain growth and reduction in dislocation density and hence led to lower strength. The higher elongations for the joints welded at higher heat inputs were due to lower dislocation density inside the grains, which was consistent with a more ductile fracture of them.

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.

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

The Underwater Spectrometric System Based on CZT Detector for Survey of the Bottom of MR Reactor Pool - 13461

DOE Office of Scientific and Technical Information (OSTI.GOV)

Potapov, Victor; Safronov, Alexey; Ivanov, Oleg

2013-07-01

The underwater spectrometer system for detection of irradiated nuclear fuel on the pool bottom of the reactor was elaborated. During the development process metrological studies of CdZnTe (CZT) detectors were conducted. These detectors are designed for spectrometric measurements in high radiation fields. A mathematical model based on the Monte Carlo method was created to evaluate the capability of such a system. A few experimental models were realized and the characteristics of the spectrometric system are represented. (authors)

Discovery and Characterization of Cold Seep Vents Using a Mass Spectrometer Operating aboard an Autonomous Underwater Vehicle

NASA Astrophysics Data System (ADS)

Camilli, R.; Macelloni, L.; Asper, V.; Woolsey, M.; Williams, J.; Diercks, A.; Lutken, C. B.; Sleeper, K.

2009-12-01

A chemical and bathymetric survey was conducted in June 2009 at a known gas hydrate site approximately 900 meters deep in the Gulf of Mexico Mississippi Canyon 118 block. This survey used the EagleRay autonomous underwater vehicle equipped with a TETHYS in-situ mass spectrometer and EM 2000 multibeam sonar. Results indicate previously unobserved active sea floor methane seeps that correlate with bathymetric depressions and a geologic fault. These data suggest linkage of the methane cold seeps to an underlying thermogenic hydrocarbon reservoir.

Surveying the Underwater Arcaheological Site of Cape Glaros at Pagasetikos Gulf

NASA Astrophysics Data System (ADS)

Diamanti, E.; Spondylis, E.; Vlachaki, F.; Kolyva, E.

2017-02-01

The Hellenic Institute of Marine Archaeology (H.I.M.A.)1 has been conducting an underwater archaeological research in the west coast of southern Pagasetikos Gulf, since 2000. Every year the underwater research focuses on specific archaeological targets that have been recovered during previous field campaigns. The current publication elaborates on the comprehensive documentation of the underwater archaeological site at Cape Glaros, during the 2015 field season, under the direction of the archaeologist Elias Spondylis. The 2015 research campaign was conducted within the framework of the ITACA- Innovation Technologies and Applications for Coastal Archaeological sites European Project (FP7/2007-2013, GA No 606805), at two archaeological sites, namely the Cape Glaros and Metohi. It was among the most important challenges of the project to successfully produce the detailed and accurate 3D mapping of the Cape Glaros site that covers an extended area. Four large concentrations of pottery finds and numerous anchors of different typology have been recorded, that can be dated from the late Hellenistic to the Byzantine periods. This challenge was tackled through the simultaneous implementation of three recording methods; photogrammetry, geodesy and conventional architectural mapping. The workflow of the documentation process, including data acquisition, processing and graphic visualization, along with the derived results are presented below. 1The Hellenic Institute of Marine Archaeology (H.I.M.A.) is a private, non-profit organization, founded in 1973, which undertakes maritime archaeological research under the supervision or in collaboration with the Greek Ministry of Culture. It has over 100 members, with diverse academic credentials, all of whom work, mainly, on a voluntary basis. 3D recording of underwater archaeological sites has been applied to numerous projects that have been carried out by the multidisciplinary team of H.I.M.A. in locations of utmost archaeological importance and interest, such as Modi island (Poros) and numerous wreck sites in Pagasetikos and South Euboean (Diamanti, Vlachaki, 2015) Gulfs and others.

Visual search strategies of experienced and nonexperienced swimming coaches.

PubMed

Moreno, Francisco J; Saavedra, José M; Sabido, Rafael; Luis, Vicente; Reina, Raúl

2006-12-01

The aim of this study consists of the application of an experimental protocol that allows information to be obtained about the visual search strategies elaborated by swimming coaches. 16 swimming coaches participated. The Experienced group (n=8) had 16.1 yr. (SD=8.2) of coaching experience and at least five years of experience in underwater vision. The Nonexperienced group in underwater vision (n= 8) had 4.2 yr. (SD= 4.0) of coaching experience. Participants were tested in a laboratory environment using a video-projected sample of the crawl stroke of an elite swimmer. This work discusses the main areas of the swimmer's body used by coaches to identify and analyse errors in technique from overhead and underwater perspectives. In front-underwater videos, body roll and mid-water were the locations of the display with higher percentages of fixation time. In the side-underwater slow videos, the upper body was the location with higher percentages of visual fixation time and was used to detect the low elbow fault. Side-overhead takes were not the best perspectives to pick up information directly about performance of the arms; coaches attended to the head as a reference for their visual search. The observation and technical analysis of the hands and arms were facilitated by an underwater perspective. Visual fixation on the elbow served as a reference to identify errors in the upper body. The side-underwater perspective may be an adequate way to identify correct knee angles in leg kicking and the alignment of a swimmer's body and leg actions.

KSC-03PD-2364

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

Design and research on the two-joint mating system of underwater vehicle

NASA Astrophysics Data System (ADS)

Zhang, Zhong-lin; Wang, Li-quan

2013-03-01

In the 21st century, people have come to the era of ocean science and ocean economy. With the development of ocean science and technology and the thorough research on the ocean, underwater mating technique has been widely used in such fields as sunk ship salvage, deep ocean workstation, submarine lifesaving aid and military affairs. In this paper, researches are made home and abroad on mating technology. Two-joint mating system of underwater vehicle is designed including plane system, three-dimensional assembly system and control system in order to increase the capacity of adapting platform obliquity and adopting rotational skirt scheme. It is clear that the system fits the working space of underwater vehicle passageway and there is no interference phenomenon in assembly design. The finite element model of the system shell and the pressurization of the joint are established. The results of the finite element computing and the pressing test are accordant, and thus it can testify that the shell material meet the need of intension and joint pressurization is reliable. Modeling of the control system is accomplished, and simulation and analysis are made, which can provide directions for the controller design of mating system of underwater vehicles.

Captive Bottlenose Dolphins Do Discriminate Human-Made Sounds Both Underwater and in the Air

PubMed Central

Lima, Alice; Sébilleau, Mélissa; Boye, Martin; Durand, Candice; Hausberger, Martine; Lemasson, Alban

2018-01-01

Bottlenose dolphins (Tursiops truncatus) spontaneously emit individual acoustic signals that identify them to group members. We tested whether these cetaceans could learn artificial individual sound cues played underwater and whether they would generalize this learning to airborne sounds. Dolphins are thought to perceive only underwater sounds and their training depends largely on visual signals. We investigated the behavioral responses of seven dolphins in a group to learned human-made individual sound cues, played underwater and in the air. Dolphins recognized their own sound cue after hearing it underwater as they immediately moved toward the source, whereas when it was airborne they gazed more at the source of their own sound cue but did not approach it. We hypothesize that they perhaps detected modifications of the sound induced by air or were confused by the novelty of the situation, but nevertheless recognized they were being “targeted.” They did not respond when hearing another group member’s cue in either situation. This study provides further evidence that dolphins respond to individual-specific sounds and that these marine mammals possess some capacity for processing airborne acoustic signals. PMID:29445350

Implementation and Testing of the JANUS Standard with SSC Pacific’s Software-Defined Acoustic Modem

DTIC Science & Technology

2017-10-01

Communications Outpost (FDECO) Innovative Naval Prototype (INP) Program by the Advanced Photonic Technologies Branch (Code 55360), Space and Naval Warfare...underwater acoustic communication operations with NATO and non-NATO military and civilian maritime assets. iv ACRONYMS SPAWAR Space and Naval Warfare...the center frequency [1]. The ease of implementation and proven robustness in harsh underwater acoustic communication channels paved the way for

Comparison of different classification algorithms for underwater target discrimination.

PubMed

Li, Donghui; Azimi-Sadjadi, Mahmood R; Robinson, Marc

2004-01-01

Classification of underwater targets from the acoustic backscattered signals is considered here. Several different classification algorithms are tested and benchmarked not only for their performance but also to gain insight to the properties of the feature space. Results on a wideband 80-kHz acoustic backscattered data set collected for six different objects are presented in terms of the receiver operating characteristic (ROC) and robustness of the classifiers wrt reverberation.

Multisensor system for the protection of critical infrastructure of a seaport

NASA Astrophysics Data System (ADS)

Kastek, Mariusz; Dulski, Rafał; Zyczkowski, Marek; Szustakowski, Mieczysław; Trzaskawka, Piotr; Ciurapinski, Wiesław; Grelowska, Grazyna; Gloza, Ignacy; Milewski, Stanislaw; Listewnik, Karol

2012-06-01

There are many separated infrastructural objects within a harbor area that may be considered "critical", such as gas and oil terminals or anchored naval vessels. Those objects require special protection, including security systems capable of monitoring both surface and underwater areas, because an intrusion into the protected area may be attempted using small surface vehicles (boats, kayaks, rafts, floating devices with weapons and explosives) as well as underwater ones (manned or unmanned submarines, scuba divers). The paper will present the concept of multisensor security system for a harbor protection, capable of complex monitoring of selected critical objects within the protected area. The proposed system consists of a command centre and several different sensors deployed in key areas, providing effective protection from land and sea, with special attention focused on the monitoring of underwater zone. The initial project of such systems will be presented, its configuration and initial tests of the selected components. The protection of surface area is based on medium-range radar and LLTV and infrared cameras. Underwater zone will be monitored by a sonar and acoustic and magnetic barriers, connected into an integrated monitoring system. Theoretical analyses concerning the detection of fast, small surface objects (such as RIB boats) by a camera system and real test results in various weather conditions will also be presented.

An underwater blood pressure measuring device.

PubMed

Sieber, Arne; Kuch, Benjamin; L'abbate, Antonio; Wagner, Matthias; Dario, Paolo; Bedini, Remo

2008-09-01

Measurement of arterial blood pressure is an important vital sign for monitoring the circulation. However, up to now no instrument has been available that enables the measurement of blood pressure underwater. The present paper details a novel, oscillometric, automatic digital blood pressure (BP) measurement device especially designed for this purpose. It consists mainly of analogue and digital electronics in a lexan housing that is rated to a depth of up to 200 metres' sea water, a cuff and a solenoid for inflation of the cuff with air supplied from a scuba tank. An integrated differential pressure sensor, exposed to the same ambient pressure as the cuff, allows accurate BP measurement. Calculation of systolic and diastolic pressures is based on the analysis of pressure oscillations recorded during the deflation. In hyperbaric chamber tests to pressures up to 405 kPa, BP measurements taken with the prototype were comparable to those obtained with established manual and automated methods. Swimming pool tests confirmed the correct functioning of the system underwater. The quality of the recorded pressure oscillations was very good even at 10 metres' fresh water, and allowed determination of diastolic and systolic pressure values. Based on these results we envisage that this device will lead to a better understanding of human cardiovascular physiology in underwater and hyperbaric environments.

Prospects for using sonar for underwater archeology on the Yenisei: surveying a 19th century shipwreck

NASA Astrophysics Data System (ADS)

Goncharov, A. E.; Mednikov, D. M.; Karelin, N. M.; Nasyrov, I. R.

2016-11-01

Current progress in underwater archeology is based on a rich arsenal of high-tech appliances, among which sonar technology plays a key role; it enables scientists not only to detect submerged archeological objects, but to examine them in high definition without having to conduct diving operations or use expensive underwater unmanned vehicles. While the majority of sensational scientific discoveries using sonar have been made in saltwater environments, freshwater ones, rivers in particular, have seen limited activity. The river Yenisei in central Siberia contains an unrecorded number of shipwrecks that await being discovered and studied. In this article we focus on the peculiarities of using sonar for detecting archeological sites on the Yenisei. This article is based on the results of the 2016 expedition, which has determined the location of Thames, a 19th century British steam schooner which was wrecked on the Yenisei.

Multi-dimensional water quality assessment of an urban drinking water source elucidated by high resolution underwater towed vehicle mapping.

PubMed

Lock, Alan; Spiers, Graeme; Hostetler, Blair; Ray, James; Wallschläger, Dirk

2016-04-15

Spatial surveys of Ramsey Lake, Sudbury, Ontario water quality were conducted using an innovative underwater towed vehicle (UTV) equipped with a multi-parameter probe providing real-time water quality data. The UTV revealed underwater vent sites through high resolution monitoring of different spatial chemical characteristics using common sensors (turbidity, chloride, dissolved oxygen, and oxidation/reduction sensors) that would not be feasible with traditional water sampling methods. Multi-parameter probe vent site identification is supported by elevated alkalinity and silica concentrations at these sites. The identified groundwater vent sites appear to be controlled by bedrock fractures that transport water from different sources with different contaminants of concern. Elevated contaminants, such as, arsenic and nickel and/or nutrient concentrations are evident at the vent sites, illustrating the potential of these sources to degrade water quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

15 CFR 922.191 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922... authorization issued by the State of Michigan for the conduct of activities or projects within the Thunder Bay...

15 CFR 922.191 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922... authorization issued by the State of Michigan for the conduct of activities or projects within the Thunder Bay...

15 CFR 922.191 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922... authorization issued by the State of Michigan for the conduct of activities or projects within the Thunder Bay...

15 CFR 922.191 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922... authorization issued by the State of Michigan for the conduct of activities or projects within the Thunder Bay...

15 CFR 922.191 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922... authorization issued by the State of Michigan for the conduct of activities or projects within the Thunder Bay...

Small Vessel Contribution to Underwater Noise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matzner, Shari; Maxwell, Adam R.; Myers, Joshua R.

2010-12-10

Understanding the types of noise generated by a small boat is important for ensuring that marine ecosystems are protected from detrimental anthropogenic noise. Here we present the results of a field test conducted to examine the effects of engine RPM, number of engines and number of propeller blades on the broadband and narrowband noise produced by a small boat. The test boat was a 23-foot aluminum-hulled boat with dual 100 hp engines. The broadband noise and narrowband peak levels were observed using two hydrophones in different locations. The broadband noise levels were affected by both the number of engines andmore » the RPM; the narrowband peaks showed a greater increase in amplitude with an increase in RPM than the broadband noise levels.« less

Link Connectivity and Coverage of Underwater Cognitive Acoustic Networks under Spectrum Constraint

PubMed Central

Wang, Qiu; Cheang, Chak Fong

2017-01-01

Extensive attention has been given to the use of cognitive radio technology in underwater acoustic networks since the acoustic spectrum became scarce due to the proliferation of human aquatic activities. Most of the recent studies on underwater cognitive acoustic networks (UCANs) mainly focus on spectrum management or protocol design. Few efforts have addressed the quality-of-service (QoS) of UCANs. In UCANs, secondary users (SUs) have lower priority to use acoustic spectrum than primary users (PUs) with higher priority to access spectrum. As a result, the QoS of SUs is difficult to ensure in UCANs. This paper proposes an analytical model to investigate the link connectivity and the probability of coverage of SUs in UCANs. In particular, this model takes both topological connectivity and spectrum availability into account, though spectrum availability has been ignored in most recent studies. We conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Simulation results show that our proposed model is quite accurate. Besides, our results also imply that the link connectivity and the probability of coverage of SUs heavily depend on both the underwater acoustic channel conditions and the activities of PUs. PMID:29215561

Neoprene wet-suit hood affects low-frequency underwater hearing thresholds.

PubMed

Fothergill, David M; Sims, John R; Curley, Michael D

2004-05-01

Psychophysical measures of wet-suit hood sound attenuation are needed to provide the diving community with guidance on protection from underwater sound. Underwater hearing thresholds were obtained from 15 male and 5 female recreational divers with and without a 3-mm thick wet-suit hood. Dives were conducted at a depth of 1 m in a large quiet anechoic pool. Thresholds were determined using a two-interval forced-choice procedure with a 0.71 probability of positive response at convergence. A 1-s pure tone was presented with a 20-ms rise and fall time at 100, 200, 250, 300, 400, and 500 Hz. Without a wet-suit hood, mean thresholds decreased from 99 dB re 1 microPa at 100 Hz to 85 dB at 500 Hz. Thresholds were statistically similar at 100 to 300 Hz with and without the wet-suit hood, but were significantly increased at 400 and 500 Hz with the hood (p < 0.001). In conclusion, at shallow depths, a 3-mm neoprene wet-suit hood attenuates underwater sound by approximately 10 dB for frequencies between 400 Hz and 500 Hz. At frequencies below 400 Hz, a 3-mm neoprene wet-suit hood offers no sound protection.

An Adaptive OFDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks

PubMed Central

Khalil, Issa M.; Gadallah, Yasser; Hayajneh, Mohammad; Khreishah, Abdallah

2012-01-01

Underwater acoustic wireless sensor networks (UAWSNs) have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA)-based Media Access Control (MAC) protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA)-based MAC protocols. PMID:23012517

An adaptive OFDMA-based MAC protocol for underwater acoustic wireless sensor networks.

PubMed

Khalil, Issa M; Gadallah, Yasser; Hayajneh, Mohammad; Khreishah, Abdallah

2012-01-01

Underwater acoustic wireless sensor networks (UAWSNs) have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA)-based Media Access Control (MAC) protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA)-based MAC protocols.

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.

Validation of Underwater Sensor Package Using Feature Based SLAM

PubMed Central

Cain, Christopher; Leonessa, Alexander

2016-01-01

Robotic vehicles working in new, unexplored environments must be able to locate themselves in the environment while constructing a picture of the objects in the environment that could act as obstacles that would prevent the vehicles from completing their desired tasks. In enclosed environments, underwater range sensors based off of acoustics suffer performance issues due to reflections. Additionally, their relatively high cost make them less than ideal for usage on low cost vehicles designed to be used underwater. In this paper we propose a sensor package composed of a downward facing camera, which is used to perform feature tracking based visual odometry, and a custom vision-based two dimensional rangefinder that can be used on low cost underwater unmanned vehicles. In order to examine the performance of this sensor package in a SLAM framework, experimental tests are performed using an unmanned ground vehicle and two feature based SLAM algorithms, the extended Kalman filter based approach and the Rao-Blackwellized, particle filter based approach, to validate the sensor package. PMID:26999142

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.

Numerical study of tsunami generated by multiple submarine slope failures in Resurrection Bay, Alaska, during the MW 9.2 1964 earthquake

USGS Publications Warehouse

Suleimani, E.; Hansen, R.; Haeussler, Peter J.

2009-01-01

We use a viscous slide model of Jiang and LeBlond (1994) coupled with nonlinear shallow water equations to study tsunami waves in Resurrection Bay, in south-central Alaska. The town of Seward, located at the head of Resurrection Bay, was hit hard by both tectonic and local landslide-generated tsunami waves during the MW 9.2 1964 earthquake with an epicenter located about 150 km northeast of Seward. Recent studies have estimated the total volume of underwater slide material that moved in Resurrection Bay during the earthquake to be about 211 million m3. Resurrection Bay is a glacial fjord with large tidal ranges and sediments accumulating on steep underwater slopes at a high rate. Also, it is located in a seismically active region above the Aleutian megathrust. All these factors make the town vulnerable to locally generated waves produced by underwater slope failures. Therefore it is crucial to assess the tsunami hazard related to local landslide-generated tsunamis in Resurrection Bay in order to conduct comprehensive tsunami inundation mapping at Seward. We use numerical modeling to recreate the landslides and tsunami waves of the 1964 earthquake to test the hypothesis that the local tsunami in Resurrection Bay has been produced by a number of different slope failures. We find that numerical results are in good agreement with the observational data, and the model could be employed to evaluate landslide tsunami hazard in Alaska fjords for the purposes of tsunami hazard mitigation. ?? Birkh??user Verlag, Basel 2009.

Exploring the Eastern United States Continental Shelf with the NOAA Cooperative Institute for Ocean Exploration, Research, and Technology

NASA Astrophysics Data System (ADS)

Glickson, D.; Pomponi, S. A.

2016-02-01

The Cooperative Institute for Ocean Exploration, Research, and Technology (CIOERT) serves NOAA priorities in three theme areas: exploring the eastern U.S. continental shelf, improving the understanding of coral and sponge ecosystems, and developing advanced underwater technologies. CIOERT focuses on the exploration and research of ecosystems and habitats along frontier regions of the eastern U.S. continental shelf that are of economic, scientific, or cultural importance or of natural hazards concern. One particular focus is supporting ocean exploration and research through the use of advanced underwater technologies and techniques in order to improve the understanding of vulnerable deep and shallow coral and sponge ecosystems. CIOERT expands the scope and efficiency of exploration and research by developing, testing, and applying new and/or innovative uses of existing technologies to ocean exploration and research activities. In addition, CIOERT is dedicated to expanding ocean literacy and building NOAA's technical and scientific workforce through hands-on, at-sea experiences. A recent CIOERT cruise characterized Gulf of Mexico mesophotic and deepwater reef ecosystems off the west Florida shelf, targeting northern Pulley Ridge. This project created and ground-truthed new sonar maps made with an autonomous underwater vehicle; conducted video and photographic transects of benthic habitat and fish using a remotely operated vehicle; and examined the connectivity of fauna from shallow to deep reef ecosystems. CIOERT was established in 2009 by FAU-Harbor Branch Oceanographic Institute, with University of North Carolina, Wilmington, SRI International, and the University of Miami. The primary NOAA partner is the Office of Oceanic and Atmospheric Research's Office of Ocean Exploration and Research.

Exploring the Eastern United States Continental Shelf with the NOAA Cooperative Institute for Ocean Exploration, Research, and Technology

NASA Astrophysics Data System (ADS)

Glickson, D.; Pomponi, S.

2015-12-01

The Cooperative Institute for Ocean Exploration, Research, and Technology (CIOERT) serves NOAA priorities in three theme areas: exploring the eastern U.S. continental shelf, improving the understanding of coral and sponge ecosystems, and developing advanced underwater technologies. CIOERT focuses on the exploration and research of ecosystems and habitats along frontier regions of the eastern U.S. continental shelf that are of economic, scientific, or cultural importance or of natural hazards concern. One particular focus is supporting ocean exploration and research through the use of advanced underwater technologies and techniques in order to improve the understanding of vulnerable deep and shallow coral and sponge ecosystems. CIOERT expands the scope and efficiency of exploration and research by developing, testing, and applying new and/or innovative uses of existing technologies to ocean exploration and research activities. In addition, CIOERT is dedicated to expanding ocean literacy and building NOAA's technical and scientific workforce through hands-on, at-sea experiences. A recent CIOERT cruise characterized Gulf of Mexico mesophotic and deepwater reef ecosystems off the west Florida shelf, targeting northern Pulley Ridge. This project created and ground-truthed new sonar maps made with an autonomous underwater vehicle; conducted video and photographic transects of benthic habitat and fish using a remotely operated vehicle; and examined the connectivity of fauna from shallow to deep reef ecosystems. CIOERT was established in 2009 by FAU-Harbor Branch Oceanographic Institute, with University of North Carolina, Wilmington, SRI International, and the University of Miami. The primary NOAA partner is the Office of Oceanic and Atmospheric Research's Office of Ocean Exploration and Research.

Distortion of Prospective Time Production Underwater.

PubMed

Hobbs, Malcolm B; Kneller, Wendy

2017-07-01

The few prior studies of time perception underwater have reached contradictory conclusions as to how, and if, time perception becomes distorted when submerged. The current paper expands upon this limited data by describing two studies of prospective time production in scuba divers. Study 1 (N = 32) compared performance on a 30-s interval time production task in deep water (35 m-42 m/∼115-138 ft) with a shallow water control (3-12 m/∼10-39 ft). Using the same task, study 2 (N = 31) tested performance at the surface and at a range of depths underwater (1 m/3 ft; 11 m/36 ft; 20 m/66 ft; 30 m/98 ft; 40 m/131 ft). Study 1 revealed time production to be significantly longer in deep water compared to shallow water. In study 2 time production at the surface was not significantly different from that at 1 m, but productions at 11-40 m were significantly longer than at both 1 m and on the surface. Time productions between 11-40 m did not differ significantly. It was concluded that divers judge less time to have passed underwater than is objectively the case from a depth of 11 m, but that this effect does not deteriorate significantly once past 11 m. The cause of this distortion of time perception underwater was suggested to be the action of gas narcosis.Hobbs MB, Kneller W. Distortion of prospective time production underwater. Aerosp Med Hum Perform. 2017; 88(7):677-681.

Fish Hearing.

ERIC Educational Resources Information Center

Blaxter, J. H. S.

1980-01-01

Provides related information about hearing in fish, including the sensory stimulus of sound in the underwater environment, mechanoreceptors in fish, pressure perception and the swimbladder, specializations in sound conduction peculiar to certain fish families. Includes numerous figures. (CS)

Cognitive factors in the close visual and magnetic particle inspection of welds underwater.

PubMed

Leach, J; Morris, P E

1998-06-01

Underwater close visual inspection (CVI) and magnetic particle inspection (MPI) are major components of the commercial diver's job of nondestructive testing and the maintenance of subsea structures. We explored the accuracy of CVI in Experiment 1 and that of MPI in Experiment 2 and observed high error rates (47% and 24%, respectively). Performance was strongly correlated with embedded figures and visual search tests and was unrelated to length of professional diving experience, formal inspection qualification, or age. Cognitive tests of memory for designs, spatial relations, dotted outlines, and block design failed to correlate with performance. Actual or potential applications of this research include more reliable inspection reporting, increased effectiveness from current inspection techniques, and directions for the refinement of subsea inspection equipment.

Underwater Test Diagnostics Using Explosively Excited Argon And Laser Light Photography Techniques

NASA Astrophysics Data System (ADS)

Wisotski, John

1990-01-01

This paper presents results of photographic methods employed in underwater tests used to study high-velocity fragment deceleration, deformation and fracture during the perforation of water-backed plates. These methods employed overlapping ultra-high and very high speed camera recordings using explosively excited argon and ruby-laser light sources that gave ample light to penetrate across a 2.3-meter (7.54-foot) diameter tank of water with enough intensity to photograph displacement-time histories of steel cubes with impact speeds of 1000 to 1500 m/s (3280 to 4920 ft/s) at camera framing rates of 250,000 and 17,000 fr/s, respectively.

Energy balance during underwater implosion of ductile metallic cylinders.

PubMed

Chamberlin, Ryan E; Guzas, Emily L; Ambrico, Joseph M

2014-11-01

Energy-based metrics are developed and applied to a numerical test case of implosion of an underwater pressure vessel. The energy metrics provide estimates of the initial energy in the system (potential energy), the energy released into the fluid as a pressure pulse, the energy absorbed by the imploding structure, and the energy absorbed by air trapped within the imploding structure. The primary test case considered is the implosion of an aluminum cylinder [diameter: 2.54 cm (1 in.), length: 27.46 cm (10.81 in.)] that collapses flat in a mode-2 shape with minimal fracture. The test case indicates that the structure absorbs the majority (92%) of the initial energy in the system. Consequently, the energy emitted as a pressure pulse into the fluid is a small fraction, approximately 5%, of the initial energy. The energy absorbed by the structure and the energy emitted into the fluid are calculated for additional simulations of underwater pressure vessel implosions. For all cases investigated, there is minimal fracture in the collapse, the structure absorbs more than 80% of the initial energy of the system, and the released pressure pulse carries away less than 6% of the initial energy.

Underwater hearing in the loggerhead turtle (Caretta caretta): a comparison of behavioral and auditory evoked potential audiograms.

PubMed

Martin, Kelly J; Alessi, Sarah C; Gaspard, Joseph C; Tucker, Anton D; Bauer, Gordon B; Mann, David A

2012-09-01

The purpose of this study was to compare underwater behavioral and auditory evoked potential (AEP) audiograms in a single captive adult loggerhead sea turtle (Caretta caretta). The behavioral audiogram was collected using a go/no-go response procedure and a modified staircase method of threshold determination. AEP thresholds were measured using subdermal electrodes placed beneath the frontoparietal scale, dorsal to the midbrain. Both methods showed the loggerhead sea turtle to have low frequency hearing with best sensitivity between 100 and 400 Hz. AEP testing yielded thresholds from 100 to 1131 Hz with best sensitivity at 200 and 400 Hz (110 dB re. 1 μPa). Behavioral testing using 2 s tonal stimuli yielded underwater thresholds from 50 to 800 Hz with best sensitivity at 100 Hz (98 dB re. 1 μPa). Behavioral thresholds averaged 8 dB lower than AEP thresholds from 100 to 400 Hz and 5 dB higher at 800 Hz. The results suggest that AEP testing can be a good alternative to measuring a behavioral audiogram with wild or untrained marine turtles and when time is a crucial factor.

A Keyboard for Underwater Performance Assessment Battery Testing

DTIC Science & Technology

1990-11-08

Applied Engineering . This four button underwater keyboard uses only a small portion of the boards capacity. The cable is connected to the I/O 32 board via a...H.O., by Applied Engineering ) require special programming to work with the IO 32 board. If the boards are accessed directly from Apple Basic with the... Applied Engineering , 1988) is presented in the Appendix. This program will work with either the enhanced or the unenhanced version of the Apple lie. 6

Underwater Simultaneous EMI and Magnetometer System (USEMS)

DTIC Science & Technology

2011-02-01

advantages over other marine metal detectors . The first is that, because the sensors are affixed via a rigid boom instead of towed with a cable...Island free of metallic clutter, emplaced a test plot with 14 pipes ranging from 1.5 to 4 inches in diameter, measured the locations of items in it with... metallic contamination. 2.3 REGULATORY DRIVERS The primary driver is the continued need to develop tools to detect underwater MEC. The documented use

The Shock and Vibration Bulletin. Part 4. Underwater Problems, Environments and Measurements

DTIC Science & Technology

1974-08-01

6585th Test Group, Holloman AFB, New Mexico FLOW-INDUCED VIBRATIONS OF A GLASS-REINFORCED PLASTIC SONAR DOME D.A. King, Rockwell International...Bolts plasticity 10 Fig 13b Fig. 13 - Underwater Explosion Experimental Results on 2.5 t Mass (Nun Linear Mount) y Energy transfer calculation...makes it possible to access the stress level which is reached in every part of the fixture system in- cluding the region of plasticity . VI

The low-frequency sound power measuring technique for an underwater source in a non-anechoic tank

NASA Astrophysics Data System (ADS)

Zhang, Yi-Ming; Tang, Rui; Li, Qi; Shang, Da-Jing

2018-03-01

In order to determine the radiated sound power of an underwater source below the Schroeder cut-off frequency in a non-anechoic tank, a low-frequency extension measuring technique is proposed. This technique is based on a unique relationship between the transmission characteristics of the enclosed field and those of the free field, which can be obtained as a correction term based on previous measurements of a known simple source. The radiated sound power of an unknown underwater source in the free field can thereby be obtained accurately from measurements in a non-anechoic tank. To verify the validity of the proposed technique, a mathematical model of the enclosed field is established using normal-mode theory, and the relationship between the transmission characteristics of the enclosed and free fields is obtained. The radiated sound power of an underwater transducer source is tested in a glass tank using the proposed low-frequency extension measuring technique. Compared with the free field, the radiated sound power level of the narrowband spectrum deviation is found to be less than 3 dB, and the 1/3 octave spectrum deviation is found to be less than 1 dB. The proposed testing technique can be used not only to extend the low-frequency applications of non-anechoic tanks, but also for measurement of radiated sound power from complicated sources in non-anechoic tanks.

The basis for the development of a fuselage evacuation time for a ditched helicopter.

PubMed

Brooks, C J; Muir, H C; Gibbs, P N

2001-06-01

When a helicopter ditches or crashes in water, unless the buoyancy bags are inflated, it commonly sinks inverted. Thus, crew and passengers must make an underwater escape. It is postulated that later passengers in the escape sequence do not have the breath-holding ability to conduct a successful escape, particularly if the water is cold. This contributes to the 20-50% mortality rate in survivable accidents. There were 132 immersed subject evaluations which were conducted in daylight and darkness to measure escape times from a helicopter underwater escape trainer, configured to the Super Puma, seated for 15 and 18 passengers. The subjects were highly experienced instructors or Navy clearance divers. The time from when each subject's head disappeared underwater until each subject surfaced and total fuselage evacuation time were measured and any problems hampering escape were noted. Breath-holding for the last subject out ranged from 28 to 92 s. An emergency breathing system was used by a minimum of four subjects each time and a maximum of 11 subjects in one condition. The buoyancy of the survival suit was the principal component that hampered escape. Breath-holding times were too long for the later subjects to escape without resorting to an EBS, in spite of the fact that they were highly trained. For regular crew and passengers flying over water, this would explain the high mortality, etc. Therefore, a new helicopter standard should be developed requiring fuselage design to accommodate total evacuation within 20 s from underwater. For current helicopters, where this cannot be achieved, passengers should be provided with some form of air supply, or, after ditching, the helicopter should be modified so that it will stay afloat on its side and retain an air space in the cabin.

Underwater sound pressure variation and bottlenose dolphin (Tursiops truncatus) hearing thresholds in a small pool.

PubMed

Finneran, James J; Schlundt, Carolyn E

2007-07-01

Studies of underwater hearing are often hampered by the behavior of sound waves in small experimental tanks. At lower frequencies, tank dimensions are often not sufficient for free field conditions, resulting in large spatial variations of sound pressure. These effects may be mitigated somewhat by increasing the frequency bandwidth of the sound stimulus, so effects of multipath interference average out over many frequencies. In this study, acoustic fields and bottlenose dolphin (Tursiops truncatus) hearing thresholds were compared for pure tone and frequency modulated signals. Experiments were conducted in a vinyl-walled, seawater-filled pool approximately 3.7 x 6 x 1.5 m. Acoustic signals were pure tone and linear and sinusoidal frequency modulated tones with bandwidths/modulation depths of 1%, 2%, 5%, 10%, and 20%. Thirteen center frequencies were tested between 1 and 100 kHz. Acoustic fields were measured (without the dolphin present) at three water depths over a 60 x 65 cm grid with a 5-cm spacing. Hearing thresholds were measured using a behavioral response paradigm and up/down staircase technique. The use of FM signals significantly improved the sound field without substantially affecting the measured hearing thresholds.

Passenger carrying submersibles : system safety analysis

DOT National Transportation Integrated Search

1989-08-01

During the past few years, several private companies have been using passenger carrying submersibles to conduct underwater sightseeing tours for tourists. For submersible operations under U.S. jurisdiction, the Coast Guard is required by law to estab...

Integrating dynamic and distributed compressive sensing techniques to enhance image quality of the compressive line sensing system for unmanned aerial vehicles application

NASA Astrophysics Data System (ADS)

Ouyang, Bing; Hou, Weilin; Caimi, Frank M.; Dalgleish, Fraser R.; Vuorenkoski, Anni K.; Gong, Cuiling

2017-07-01

The compressive line sensing imaging system adopts distributed compressive sensing (CS) to acquire data and reconstruct images. Dynamic CS uses Bayesian inference to capture the correlated nature of the adjacent lines. An image reconstruction technique that incorporates dynamic CS in the distributed CS framework was developed to improve the quality of reconstructed images. The effectiveness of the technique was validated using experimental data acquired in an underwater imaging test facility. Results that demonstrate contrast and resolution improvements will be presented. The improved efficiency is desirable for unmanned aerial vehicles conducting long-duration missions.

KSC-03PD-2379

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers are positioned on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2365

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2376

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers are positioned on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2366

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

Validation of trophic and anthropic underwater noise as settlement trigger in blue mussels

NASA Astrophysics Data System (ADS)

Jolivet, Aurélie; Tremblay, Rejean; Olivier, Fréderic; Gervaise, Cédric; Sonier, Rémi; Genard, Bertrand; Chauvaud, Laurent

2016-09-01

Like the majority of benthic invertebrates, the blue mussel Mytilus edulis has a bentho-pelagic cycle with its larval settlement being a complex phenomenon involving numerous factors. Among these factors, underwater noise and pelagic trophic conditions have been weakly studied in previous researches. Under laboratory conditions, we tested the hypothesis that picoplankton assimilation by the pediveliger blue mussel larvae acts as a food cue that interacts with anthropic underwater sound to stimulate settlement. We used 13C-labeling microalgae to validate the assimilation of different picoplankton species in the tissues of pediveliger larvae. Our results clearly confirm our hypothesis with a significant synergic effect of these two factors. However, only the picoeukaryotes strains assimilated by larvae stimulated the settlement, whereas the non-ingested picocyanobacteria did not. Similar positive responses were observed with underwater sound characterized by low frequency vessel noises. The combination of both factors (trophic and vessel noise) drastically increased the mussel settlement by an order of 4 compared to the control (without picoplankton and noise). Settlement levels ranged from 16.5 to 67% in 67 h.

Comparative assessment of amphibious hearing in pinnipeds.

PubMed

Reichmuth, Colleen; Holt, Marla M; Mulsow, Jason; Sills, Jillian M; Southall, Brandon L

2013-06-01

Auditory sensitivity in pinnipeds is influenced by the need to balance efficient sound detection in two vastly different physical environments. Previous comparisons between aerial and underwater hearing capabilities have considered media-dependent differences relative to auditory anatomy, acoustic communication, ecology, and amphibious life history. New data for several species, including recently published audiograms and previously unreported measurements obtained in quiet conditions, necessitate a re-evaluation of amphibious hearing in pinnipeds. Several findings related to underwater hearing are consistent with earlier assessments, including an expanded frequency range of best hearing in true seals that spans at least six octaves. The most notable new results indicate markedly better aerial sensitivity in two seals (Phoca vitulina and Mirounga angustirostris) and one sea lion (Zalophus californianus), likely attributable to improved ambient noise control in test enclosures. An updated comparative analysis alters conventional views and demonstrates that these amphibious pinnipeds have not necessarily sacrificed aerial hearing capabilities in favor of enhanced underwater sound reception. Despite possessing underwater hearing that is nearly as sensitive as fully aquatic cetaceans and sirenians, many seals and sea lions have retained acute aerial hearing capabilities rivaling those of terrestrial carnivores.

Underwater sound radiation patterns of contemporary merchant ships

NASA Astrophysics Data System (ADS)

Gassmann, M.; Wiggins, S. M.; Hildebrand, J. A.

2016-12-01

Merchant ships radiate underwater sound as an unintended by-product of their operation and as consequence contribute significantly to low-frequency, man-made noise in the ocean. Current measurement standards for the description of underwater sound from ships (ISO 17208-1:2016 and ANSI S12.64-2009) require nominal hydrophone depths of 15°, 30° and 45° at the starboard and portside of the test vessel.To opportunistically study the underwater sound of contemporary merchant ships that were tracked by the Automatic Identification System (AIS), an array of seven high-frequency acoustic recording packages (HARPs) with a sampling frequency of 200 kHz was deployed in the Santa Barbara Channel in the primary outgoing shipping lane for the port of Los Angeles and Long Beach. The vertical and horizontal aperture of the array allowed for starboard and portside measurements at all standard-required nominal hydrophone depths in addition to measurements taken at the keel aspect. Based on these measurements, frequency-dependent radiation patterns of contemporary merchant ships were estimated and used to evaluate current standards for computing ship source levels.

Long-term measurements of acoustic background noise in very deep sea

NASA Astrophysics Data System (ADS)

Riccobene, G.; NEMO Collaboration

2009-06-01

The NEMO (NEutrino Mediterranean Observatory) Collaboration installed, 25 km E offshore the port of Catania (Sicily) at 2000 m depth, an underwater laboratory to perform long-term tests of prototypes and new technologies for an underwater high energy neutrino km-scale detector in the Mediterranean Sea. In this framework the Collaboration deployed and successfully operated for about two years, starting from January 2005, an experimental apparatus for on-line monitoring of deep-sea noise. The station was equipped with four hydrophones and it is operational in the range 30 Hz-43 kHz. This interval of frequencies matches the range suitable for the proposed acoustic detection technique of high energy neutrinos. Hydrophone signals were digitized underwater at 96 kHz sampling frequency and 24 bits resolution. The stored data library, consisting of more than 2000 h of recordings, is a unique tool to model underwater acoustic noise at large depth, to characterize its variations as a function of environmental parameters, biological sources and human activities (ship traffic, etc.), and to determine the presence of cetaceans in the area.

A High-Speed Optical Modem Communication System for CORK Seafloor Observatories

NASA Astrophysics Data System (ADS)

Farr, N.; Tivey, M.; Ware, J.; Pontbriand, C.; Pelletier, L. P.

2014-12-01

High-speed communications underwater is an increasing requirement for data intensive seafloor sensors. Acoustic modems provide dependable long-range communications underwater, but data rates are limited to <57Kbps. Free-water optical modems (OMs) offer high data rate, 10Mbps communications over a range of 200 m - a distance for ROVs, AUVs or wire-lowered packages to communicate without the need to directly plug-in or retrieve the instrument. Over the past 4 years, we have demonstrated the functionality and utility of OM technology using a CORK borehole observatory as a test case. A CORK represents all of the basic components required for a seafloor observatory: a stable environment for long-term continuous measurements of earth and ocean phenomena, access to a unique environment below the seafloor and a standard communication interface. The CORK-OM features a high-bandwidth, low-latency optical system based on LED emitters and PMT receivers and an acoustic command and control system. OM tests established a communication link from 20 to 200 meters range at rates of 1, 5 and 10 Mbps with no bit errors. The seafloor OM was plugged into the CORK's existing underwater wet mateable connector and provided additional power to the CORK to boost the data rate to 1 Hz from the normal 1 minute sample period. To communicate with the seafloor CORK-OM, a number of different modalities were used. One method was an OM mounted to a CTD frame on a lowered wire from a ship with an SDSL link over the conducting wire. Other methods utilized OMs mounted to both ROV Jason and submersible Alvin. We deployed OMs at two CORKs in 2012 in the northeast pacific at sites 857D and 1025C. The CORKs were visited in 2013 by a vessel of opportunity to download data and were put into sleep mode. The CORKs were revisited in 2014, woken up and successfully interrogated for data. ALVIN retrieved the CORK-OMs for corrosion, biofouling and battery performance assessment. We also performed tests of a next generation OM using a deployed seafloor modem and AUV Sentry. A complete lambertian optical field was quantitatively mapped by Sentry and test data was successfully downloaded from 20 to 150 m slant range. The AUV modality demonstrates the capability of 'data-mule' operations to autonomously recover data from a seafloor observatory with minimal human intervention.

78 FR 40436 - Takes of Marine Mammals Incidental to Specified Activities; Navy Training Conducted at the Silver...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-05

... break, presence of glassy foam, and/or perhaps scattered whitecaps). EOD or NSW personnel can be... proposed IHA notice (78 FR 24161, April 24, 2013), the Navy will conduct an underwater acoustic propagation monitoring project during the first available ELCAS deployment at the SSTC. The acoustic monitoring will...

Underwater noise assessment in the Gulf of Trieste (Northern Adriatic Sea, Italy) using an MSFD approach.

PubMed

Codarin, Antonio; Picciulin, Marta

2015-12-30

In the marine environment, underwater noise is one of the most widespread input of man-made energy. Recently, the European Commission has stressed the necessity of establishing threshold levels as a target for the descriptor 11.2.1 "Continuous low frequency sounds" in the Marine Strategy Framework Directive (MSFD). In 2012, a monthly underwater noise monitoring programme was conducted in the Gulf of Trieste (Northern Adriatic Sea, Italy); the collected acoustic samples (frequency range: 10-20,000 Hz) were analysed in the 1/3 octave bands. The stations have been further clustered following the 63 and 125 Hz bands noise levels. Average SPL levels resulted similar to those previously computed for proximate areas, indicating that the Adriatic Sea sub-region experiences high noise pressure in the marine waters. In its turn this claims for a scientific and technical international cooperation, as requested by the EU programme. No seasonal variation in local noise levels has been found. Copyright © 2015 Elsevier Ltd. All rights reserved.

Impacts of Underwater Noise on Marine Vertebrates: Project Introduction and First Results.

PubMed

Liebschner, Alexander; Seibel, Henrike; Teilmann, Jonas; Wittekind, Dietrich; Parmentier, Eric; Dähne, Michael; Dietz, Rune; Driver, Jörg; van Elk, Cornelis; Everaarts, Eligius; Findeisen, Henning; Kristensen, Jacob; Lehnert, Kristina; Lucke, Klaus; Merck, Thomas; Müller, Sabine; Pawliczka, Iwona; Ronnenberg, Katrin; Rosenberger, Tanja; Ruser, Andreas; Tougaard, Jakob; Schuster, Max; Sundermeyer, Janne; Sveegaard, Signe; Siebert, Ursula

2016-01-01

The project conducts application-oriented research on impacts of underwater noise on marine vertebrates in the North and Baltic Seas. In distinct subprojects, the hearing sensitivity of harbor porpoises and gray seals as well as the acoustic tolerance limit of harbor porpoises to impulsive noise from pile driving and stress reactions caused by anthropogenic noise is investigated. Animals are equipped with DTAGs capable of recording the actual surrounding noise field of free-swimming harbor porpoises and seals. Acoustic noise mapping including porpoise detectors in the Natura 2000 sites of the North and Baltic Seas will help to fully understand current noise impacts.

Aided target recognition processing of MUDSS sonar data

NASA Astrophysics Data System (ADS)

Lau, Brian; Chao, Tien-Hsin

1998-09-01

The Mobile Underwater Debris Survey System (MUDSS) is a collaborative effort by the Navy and the Jet Propulsion Lab to demonstrate multi-sensor, real-time, survey of underwater sites for ordnance and explosive waste (OEW). We describe the sonar processing algorithm, a novel target recognition algorithm incorporating wavelets, morphological image processing, expansion by Hermite polynomials, and neural networks. This algorithm has found all planted targets in MUDSS tests and has achieved spectacular success upon another Coastal Systems Station (CSS) sonar image database.

Procedures manual for compressed air diving (scuba mode).

DOT National Transportation Integrated Search

1980-01-01

The Virginia Department of Highways and Transportation conducts underwater inspection, maintenance, and salvage activities as part of its routine operations. These activities are carried out by divers from the private sector working on a contract bas...

A methodology for conducting underwater archaeological surveys : final report.

DOT National Transportation Integrated Search

1990-01-01

Departments of transportation and other construction agencies are required to locate and conserve cultural resources located in the area of a construction project. Although most organizations have procedures for locating cultural resources on land, t...

Maritime and Underwater Cultural Heritage Initiatives in Tanzania and Mozambique

NASA Astrophysics Data System (ADS)

Jeffery, Bill; Parthesius, Robert

2013-06-01

The aim of this paper is provide an overview of the capacity building programmes in maritime and underwater cultural heritage (MUCH) conducted by the authors in Tanzania and Mozambique. Tanzania and Mozambique have long histories of indigenous cultures, foreign contacts and influences and African adaptations beginning in the late Greco-Roman period, when the coastal populations exploited the peoples and riches of the interior. Today the coastline contains numerous examples of indigenous tangible and intangible heritage and many sites and histories related to the Swahili culture. Some exploratory research and training has been conducted in Tanzania and Mozambique, but the implementation by local residents of their own MUCH programme is still at an early stage. Under a UNESCO agreement framework, Tanzania in particular has started to develop a MUCH programme, which can assist in highlighting their extensive histories, cultural landscapes and cultural identity.

Forced underwater laminar flows with active magnetohydrodynamic metamaterials

NASA Astrophysics Data System (ADS)

Culver, Dean; Urzhumov, Yaroslav

2017-12-01

Theory and practical implementations for wake-free propulsion systems are proposed and proven with computational fluid dynamic modeling. Introduced earlier, the concept of active hydrodynamic metamaterials is advanced by introducing magnetohydrodynamic metamaterials, structures with custom-designed volumetric distribution of Lorentz forces acting on a conducting fluid. Distributions of volume forces leading to wake-free, laminar flows are designed using multivariate optimization. Theoretical indications are presented that such flows can be sustained at arbitrarily high Reynolds numbers. Moreover, it is shown that in the limit Re ≫102 , a fixed volume force distribution may lead to a forced laminar flow across a wide range of Re numbers, without the need to reconfigure the force-generating metamaterial. Power requirements for such a device are studied as a function of the fluid conductivity. Implications to the design of distributed propulsion systems underwater and in space are discussed.

A new technique for robot vision in autonomous underwater vehicles using the color shift in underwater imaging

DTIC Science & Technology

2017-06-01

FOR ROBOT VISION IN AUTONOMOUS UNDERWATER VEHICLES USING THE COLOR SHIFT IN UNDERWATER IMAGING by Jake A. Jones June 2017 Thesis Advisor...June 2017 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE A NEW TECHNIQUE FOR ROBOT VISION IN AUTONOMOUS UNDERWATER...Developing a technique for underwater robot vision is a key factor in establishing autonomy in underwater vehicles. A new technique is developed and

High speed visible light communication using blue GaN laser diodes

NASA Astrophysics Data System (ADS)

Watson, S.; Viola, S.; Giuliano, G.; Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Targowski, G.; Watson, M. A.; White, H.; Rowe, D.; Laycock, L.; Kelly, A. E.

2016-10-01

GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmission can be achieved in free space by modulating the visible light from the laser with a pseudo-random bit sequence (PRBS), with recent results approaching 5 Gbit/s error free data transmission. By exploiting the low-loss in the blue part of the spectrum through water, data transmission experiments have also been conducted to show rates of 2.5 Gbit/s underwater. Different water types have been tested to monitor the effect of scattering and to see how this affects the overall transmission rate and distance. This is of great interest for communication with unmanned underwater vehicles (UUV) as the current method using acoustics is much slower and vulnerable to interception. These types of laser diodes can typically reach 50-100 mW of power which increases the length at which the data can be transmitted. This distance could be further improved by making use of high power laser arrays. Highly uniform GaN substrates with low defectivity allow individually addressable laser bars to be fabricated. This could ultimately increase optical power levels to 4 W for a 20-emitter array. Overall, the development of GaN laser diodes will play an important part in free space optical communications and will be vital in the advancement of security and defence applications.

Remote high-definition rotating video enables fast spatial survey of marine underwater macrofauna and habitats.

PubMed

Pelletier, Dominique; Leleu, Kévin; Mallet, Delphine; Mou-Tham, Gérard; Hervé, Gilles; Boureau, Matthieu; Guilpart, Nicolas

2012-01-01

Observing spatial and temporal variations of marine biodiversity from non-destructive techniques is central for understanding ecosystem resilience, and for monitoring and assessing conservation strategies, e.g. Marine Protected Areas. Observations are generally obtained through Underwater Visual Censuses (UVC) conducted by divers. The problems inherent to the presence of divers have been discussed in several papers. Video techniques are increasingly used for observing underwater macrofauna and habitat. Most video techniques that do not need the presence of a diver use baited remote systems. In this paper, we present an original video technique which relies on a remote unbaited rotating remote system including a high definition camera. The system is set on the sea floor to record images. These are then analysed at the office to quantify biotic and abiotic sea bottom cover, and to identify and count fish species and other species like marine turtles. The technique was extensively tested in a highly diversified coral reef ecosystem in the South Lagoon of New Caledonia, based on a protocol covering both protected and unprotected areas in major lagoon habitats. The technique enabled to detect and identify a large number of species, and in particular fished species, which were not disturbed by the system. Habitat could easily be investigated through the images. A large number of observations could be carried out per day at sea. This study showed the strong potential of this non obtrusive technique for observing both macrofauna and habitat. It offers a unique spatial coverage and can be implemented at sea at a reasonable cost by non-expert staff. As such, this technique is particularly interesting for investigating and monitoring coastal biodiversity in the light of current conservation challenges and increasing monitoring needs.

Ethylene-promoted elongation: an adaptation to submergence stress.

PubMed

Jackson, Michael B

2008-01-01

A sizeable minority of taxa is successful in areas prone to submergence. Many such plants elongate with increased vigour when underwater. This helps to restore contact with the aerial environment by shortening the duration of inundation. Poorly adapted species are usually incapable of this underwater escape. Evidence implicating ethylene as the principal factor initiating fast underwater elongation by leaves or stems is evaluated comprehensively along with its interactions with other hormones and gases. These interactions make up a sequence of events that link the perception of submergence to a prompt acceleration of extension. The review encompasses whole plant physiology, cell biology and molecular genetics. It includes assessments of how submergence threatens plant life and of the extent to which the submergence escape demonstrably improves the likelihood of survival. Experimental testing over many years establishes ethylene-promoted underwater extension as one of the most convincing examples of hormone-mediated stress adaptation by plants. The research has utilized a wide range of species that includes numerous angiosperms, a fern and a liverwort. It has also benefited from detailed physiological and molecular studies of underwater elongation by rice (Oryza sativa) and the marsh dock (Rumex palustris). Despite complexities and interactions, the work reveals that the signal transduction pathway is initiated by the simple expediency of physical entrapment of ethylene within growing cells by a covering of water.

Ontogenetic investigation of underwater hearing capabilities in loggerhead sea turtles (Caretta caretta) using a dual testing approach.

PubMed

Lavender, Ashley L; Bartol, Soraya M; Bartol, Ian K

2014-07-15

Sea turtles reside in different acoustic environments with each life history stage and may have different hearing capacity throughout ontogeny. For this study, two independent yet complementary techniques for hearing assessment, i.e. behavioral and electrophysiological audiometry, were employed to (1) measure hearing in post-hatchling and juvenile loggerhead sea turtles Caretta caretta (19-62 cm straight carapace length) to determine whether these migratory turtles exhibit an ontogenetic shift in underwater auditory detection and (2) evaluate whether hearing frequency range and threshold sensitivity are consistent in behavioral and electrophysiological tests. Behavioral trials first required training turtles to respond to known frequencies, a multi-stage, time-intensive process, and then recording their behavior when they were presented with sound stimuli from an underwater speaker using a two-response forced-choice paradigm. Electrophysiological experiments involved submerging restrained, fully conscious turtles just below the air-water interface and recording auditory evoked potentials (AEPs) when sound stimuli were presented using an underwater speaker. No significant differences in behavior-derived auditory thresholds or AEP-derived auditory thresholds were detected between post-hatchling and juvenile sea turtles. While hearing frequency range (50-1000/1100 Hz) and highest sensitivity (100-400 Hz) were consistent in audiograms pooled by size class for both behavior and AEP experiments, both post-hatchlings and juveniles had significantly higher AEP-derived than behavior-derived auditory thresholds, indicating that behavioral assessment is a more sensitive testing approach. The results from this study suggest that post-hatchling and juvenile loggerhead sea turtles are low-frequency specialists, exhibiting little differences in threshold sensitivity and frequency bandwidth despite residence in acoustically distinct environments throughout ontogeny. © 2014. Published by The Company of Biologists Ltd.

Matrix effect of sodium compounds on the determination of metal ions in aqueous solutions by underwater laser-induced breakdown spectroscopy

DOE PAGES

Goueguel, Christian; McIntyre, Dustin L.; Jain, Jinesh; ...

2015-06-30

A significant portion of the carbon sequestration research being performed in the United States involves the risk assessment of injecting large quantities of carbon dioxide into deep saline aquifers. Leakage of CO 2 has the potential to affect the quality of groundwater supplies in case contaminants migrate through underlying conduits. New remote sensing and near-surface monitoring technologies are needed to ensure that injection, abandoned, and monitoring wells are structurally sound, and that CO 2 remains within the geologic storage reservoir. In this paper, we propose underwater laser-induced breakdown spectroscopy (underwater LIBS) as an analytical method for monitoring naturally occurring elementsmore » that can act as tracers to detect a CO 2 leak from storage sites. Laboratory-scale experiments were conducted to measure Sr 2+, Ca 2+, K +, and Li + in bulk solutions to ascertain the analytical performance of underwater LIBS. We compared the effect of NaCl, Na 2CO 3, and Na 2SO 4 on the analytes calibration curves to determine underwater LIBS’ ability to analyze samples of sodium compounds. In all cases, the calibration curves showed a good linearity within 2 orders of magnitude. The limit of detections (LODs) obtained for K + (30±1 ppb) and Li + (60±2 ppb) were in ppb range, while higher LODs were observed for Ca 2+ (0.94±0.14 ppm) and Sr 2+ (2.89±0.11 ppm). Evaluation of the calibration curves for the analytes in mixed solutions showed dependence of the lines’ intensity with the sodium compounds. The intensities increased respectively in the presence of dissolved NaCl and Na 2SO 4, whereas the intensities slightly decreased in the presence of Na 2CO 3. Lastly, the capabilities of underwater LIBS to detect certain elements in the ppb or in the low ppm range make it particularly appealing for in situ monitoring of a CO 2 leak.« less

Matrix effect of sodium compounds on the determination of metal ions in aqueous solutions by underwater laser-induced breakdown spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goueguel, Christian; McIntyre, Dustin L.; Jain, Jinesh

A significant portion of the carbon sequestration research being performed in the United States involves the risk assessment of injecting large quantities of carbon dioxide into deep saline aquifers. Leakage of CO 2 has the potential to affect the quality of groundwater supplies in case contaminants migrate through underlying conduits. New remote sensing and near-surface monitoring technologies are needed to ensure that injection, abandoned, and monitoring wells are structurally sound, and that CO 2 remains within the geologic storage reservoir. In this paper, we propose underwater laser-induced breakdown spectroscopy (underwater LIBS) as an analytical method for monitoring naturally occurring elementsmore » that can act as tracers to detect a CO 2 leak from storage sites. Laboratory-scale experiments were conducted to measure Sr 2+, Ca 2+, K +, and Li + in bulk solutions to ascertain the analytical performance of underwater LIBS. We compared the effect of NaCl, Na 2CO 3, and Na 2SO 4 on the analytes calibration curves to determine underwater LIBS’ ability to analyze samples of sodium compounds. In all cases, the calibration curves showed a good linearity within 2 orders of magnitude. The limit of detections (LODs) obtained for K + (30±1 ppb) and Li + (60±2 ppb) were in ppb range, while higher LODs were observed for Ca 2+ (0.94±0.14 ppm) and Sr 2+ (2.89±0.11 ppm). Evaluation of the calibration curves for the analytes in mixed solutions showed dependence of the lines’ intensity with the sodium compounds. The intensities increased respectively in the presence of dissolved NaCl and Na 2SO 4, whereas the intensities slightly decreased in the presence of Na 2CO 3. Lastly, the capabilities of underwater LIBS to detect certain elements in the ppb or in the low ppm range make it particularly appealing for in situ monitoring of a CO 2 leak.« less

Reversible switch between underwater superaerophilicity and superaerophobicity on the superhydrophobic nanowire-haired mesh for controlling underwater bubble wettability

NASA Astrophysics Data System (ADS)

Shan, Chao; Yong, Jiale; Yang, Qing; Chen, Feng; Huo, Jinglan; Zhuang, Jian; Jiang, Zhuangde; Hou, Xun

2018-04-01

Controlling the underwater bubble wettability on a solid surface is of great research significance. In this letter, a simple method to achieve reversible switch between underwater superaerophilicity and underwater superaerophobicity on a superhydrophobic nanowire-haired mesh by alternately vacuumizing treatment in water and drying in air is reported. Such reversible switch endows the as-prepared mesh with many functional applications in controlling bubble's behavior on a solid substrate. The underwater superaerophilic mesh is able to absorb/capture bubbles in water, while the superaerophobic mesh has great anti-bubble ability. The reversible switch between underwater superaerophilicity and superaerophobicity can selectively allow bubbles to go through the resultant mesh; that is, bubbles can pass through the underwater superaerophilic mesh while are fully intercepted by the underwater superaerophobic mesh in a water medium. We believe these meshes will have important applications in removing or capturing underwater bubbles/gas.

Underwater Turbulence Detection Using Gated Wavefront Sensing Technique

PubMed Central

Bi, Ying; Xu, Xiping; Chow, Eddy Mun Tik

2018-01-01

Laser sensing has been applied in various underwater applications, ranging from underwater detection to laser underwater communications. However, there are several great challenges when profiling underwater turbulence effects. Underwater detection is greatly affected by the turbulence effect, where the acquired image suffers excessive noise, blurring, and deformation. In this paper, we propose a novel underwater turbulence detection method based on a gated wavefront sensing technique. First, we elaborate on the operating principle of gated wavefront sensing and wavefront reconstruction. We then setup an experimental system in order to validate the feasibility of our proposed method. The effect of underwater turbulence on detection is examined at different distances, and under different turbulence levels. The experimental results obtained from our gated wavefront sensing system indicate that underwater turbulence can be detected and analyzed. The proposed gated wavefront sensing system has the advantage of a simple structure and high detection efficiency for underwater environments. PMID:29518889

Research on the strategy of underwater united detection fusion and communication using multi-sensor

NASA Astrophysics Data System (ADS)

Xu, Zhenhua; Huang, Jianguo; Huang, Hai; Zhang, Qunfei

2011-09-01

In order to solve the distributed detection fusion problem of underwater target detection, when the signal to noise ratio (SNR) of the acoustic channel is low, a new strategy for united detection fusion and communication using multiple sensors was proposed. The performance of detection fusion was studied and compared based on the Neyman-Pearson principle when the binary phase shift keying (BPSK) and on-off keying (OOK) modes were used by the local sensors. The comparative simulation and analysis between the optimal likelihood ratio test and the proposed strategy was completed, and both the theoretical analysis and simulation indicate that using the proposed new strategy could improve the detection performance effectively. In theory, the proposed strategy of united detection fusion and communication is of great significance to the establishment of an underwater target detection system.

Masking in three pinnipeds: underwater, low-frequency critical ratios.

PubMed

Southall, B L; Schusterman, R J; Kastak, D

2000-09-01

Behavioral techniques were used to determine underwater masked hearing thresholds for a northern elephant seal (Mirounga angustirostris), a harbor seal (Phoca vitulina), and a California sea lion (Zalophus californianus). Octave-band white noise maskers were centered at five test frequencies ranging from 200 to 2500 Hz; a slightly wider noise band was used for testing at 100 Hz. Critical ratios were calculated at one masking noise level for each test frequency. Above 200 Hz, critical ratios increased with frequency. This pattern is similar to that observed in most animals tested, and indicates that these pinnipeds lack specializations for detecting low-frequency tonal sounds in noise. However, the individual pinnipeds in this study, particularly the northern elephant seal, detected signals at relatively low signal-to-noise ratios. These results provide a means of estimating zones of auditory masking for pinnipeds exposed to anthropogenic noise sources.

Taiwan's underwater cultural heritage documentation management

NASA Astrophysics Data System (ADS)

Tung, Y.-Y.

2015-09-01

Taiwan is an important trading and maritime channels for many countries since ancient time. Numerous relics lie underwater due to weather, wars, and other factors. In the year of 2006, Bureau of Cultural Heritage (BOCH) entrusted the Underwater Archaeological Team of Academia Sinica to execute the underwater archaeological investigation projects. Currently, we verified 78 underwater targets, with 78 site of those had been recognized as shipwrecks sites. Up to date, there is a collection of 638 underwater objects from different underwater archaeological sites. Those artefacts are distributed to different institutions and museums. As very diverse management methods/systems are applied for every individual institution, underwater cultural heritage data such as survey, excavation report, research, etc. are poorly organized and disseminated for use. For better communication regarding to Taiwan's underwater cultural heritage in every level, a universal format of documentation should be established. By comparing the existing checklist used in Taiwan with guidelines that are followed in other countries, a more intact and appropriate underwater cultural heritage condition documentation system can be established and adapted in Taiwan.

75 FR 5575 - Taking and Importing Marine Mammals; Navy Training Activities Conducted in the Gulf of Alaska

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-03

... present in the area to sound from various active tactical sonar sources or to pressure from underwater... utilizing mid- and high frequency active sonar sources and explosive detonations. These sonar and explosive...

46 CFR 115.650 - Alternative Hull Examination (AHE) Program options: Divers or underwater ROV.

Code of Federal Regulations, 2011 CFR

2011-10-01

... ultrasonic thickness gaugings at a minimum of 5 points on each plate, evenly spaced; (4) Take hull plating... the Officer in Charge, Marine Inspection (OCMI) prior to conducting the survey. If you choose this...

46 CFR 115.650 - Alternative Hull Examination (AHE) Program options: Divers or underwater ROV.

Code of Federal Regulations, 2014 CFR

2014-10-01

... ultrasonic thickness gaugings at a minimum of 5 points on each plate, evenly spaced; (4) Take hull plating... the Officer in Charge, Marine Inspection (OCMI) prior to conducting the survey. If you choose this...

46 CFR 115.650 - Alternative Hull Examination (AHE) Program options: Divers or underwater ROV.

Code of Federal Regulations, 2012 CFR

2012-10-01

... ultrasonic thickness gaugings at a minimum of 5 points on each plate, evenly spaced; (4) Take hull plating... the Officer in Charge, Marine Inspection (OCMI) prior to conducting the survey. If you choose this...

46 CFR 115.650 - Alternative Hull Examination (AHE) Program options: Divers or underwater ROV.

Code of Federal Regulations, 2013 CFR

2013-10-01

... ultrasonic thickness gaugings at a minimum of 5 points on each plate, evenly spaced; (4) Take hull plating... the Officer in Charge, Marine Inspection (OCMI) prior to conducting the survey. If you choose this...

KSC-03PD-2377

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members take their places on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2384

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin retrieve some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2381

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2369

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Dr. Grant Gilmore (left), Dynamac Corp., talks to another member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

Crystallization to polycrystalline silicon thin film and simultaneous inactivation of electrical defects by underwater laser annealing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Machida, Emi; Research Fellowships of the Japan Society for the Promotion of Science, Japan Society for the Promotion of Science, 1-8 Chiyoda, Tokyo 102-8472; Horita, Masahiro

2012-12-17

We propose a low-temperature laser annealing method of a underwater laser annealing (WLA) for polycrystalline silicon (poly-Si) films. We performed crystallization to poly-Si films by laser irradiation in flowing deionized-water where KrF excimer laser was used for annealing. We demonstrated that the maximum value of maximum grain size of WLA samples was 1.5 {mu}m, and that of the average grain size was 2.8 times larger than that of conventional laser annealing in air (LA) samples. Moreover, WLA forms poly-Si films which show lower conductivity and larger carrier life time attributed to fewer electrical defects as compared to LA poly-Si films.

Effect of Water Cooling on the Performances of Friction Stir Welding Heat-Affected Zone

NASA Astrophysics Data System (ADS)

Zhang, H. J.; Liu, H. J.; Yu, L.

2012-07-01

The heat-affected zone (HAZ) is generally the intrinsic weakest location of the normal friction stir welded precipitate hardened aluminum alloys. In order to improve the mechanical properties of the HAZ by controlling the temperature level, underwater friction stir welding (FSW) of an Al-Cu aluminum alloy was conducted in the present study. The results indicate that the hardness of the HAZ can be improved through underwater FSW. Microstructural analysis reveals that the hardness improvement is attributed to the lowering of precipitate coarsening level and the narrowing of precipitate free zone, which are essentially induced by the variations of welding thermal cycles under the cooling effect of water.

Underwater audiogram of a tucuxi (Sotalia fluviatilis guianensis).

PubMed

Sauerland, M; Dehnhardt, G

1998-02-01

Using a go/no go response paradigm, a tucuxi (Sotalia fluviatilis guianensis) was trained to respond to pure-tone signals for an underwater hearing test. Auditory thresholds were obtained from 4 to 135 kHz. The audiogram curve shows that this Sotalia had an upper limit of hearing at 135 kHz; from 125 to 135 kHz sensitivity decreased by 475 dB/oct. This coincides with results from electrophysiological threshold measurements. The range of best hearing (defined as 10 dB from maximum sensitivity) was between 64 and 105 kHz. This range appears to be narrower and more restricted to higher frequencies in Sotalia fluviatilis guianensis than in other odontocete species that had been tested before. Peak frequencies of echolocation pulses reported from free-ranging Sotalia correspond with the range of most sensitive hearing of this test subject.

Sound transmission in archaic and modern whales: anatomical adaptations for underwater hearing.

PubMed

Nummela, Sirpa; Thewissen, J G M; Bajpai, Sunil; Hussain, Taseer; Kumar, Kishor

2007-06-01

The whale ear, initially designed for hearing in air, became adapted for hearing underwater in less than ten million years of evolution. This study describes the evolution of underwater hearing in cetaceans, focusing on changes in sound transmission mechanisms. Measurements were made on 60 fossils of whole or partial skulls, isolated tympanics, middle ear ossicles, and mandibles from all six archaeocete families. Fossil data were compared with data on two families of modern mysticete whales and nine families of modern odontocete cetaceans, as well as five families of noncetacean mammals. Results show that the outer ear pinna and external auditory meatus were functionally replaced by the mandible and the mandibular fat pad, which posteriorly contacts the tympanic plate, the lateral wall of the bulla. Changes in the ear include thickening of the tympanic bulla medially, isolation of the tympanoperiotic complex by means of air sinuses, functional replacement of the tympanic membrane by a bony plate, and changes in ossicle shapes and orientation. Pakicetids, the earliest archaeocetes, had a land mammal ear for hearing in air, and used bone conduction underwater, aided by the heavy tympanic bulla. Remingtonocetids and protocetids were the first to display a genuine underwater ear where sound reached the inner ear through the mandibular fat pad, the tympanic plate, and the middle ear ossicles. Basilosaurids and dorudontids showed further aquatic adaptations of the ossicular chain and the acoustic isolation of the ear complex from the skull. The land mammal ear and the generalized modern whale ear are evolutionarily stable configurations, two ends of a process where the cetacean mandible might have been a keystone character. 2007 Wiley-Liss, Inc.

Investigation of the potential effects of underwater noise from petroleum-industry activities on feeding humpback whale behavior. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malme, C.I.; Miles, P.R.; Tyack, P.

1985-06-01

An investigation was made of the potential effects of underwater noise from petroleum-industry activities on the behavior of feeding humpback whales in Frederick Sound and Stephens Passage, Alaska in August, 1984. Test sounds were a 100 cu. in. air gun and playbacks of recorded drillship, drilling platform, production platform, semi-submersible drill rig, and helicopter fly-over noise. Sound source levels and acoustic propagation losses were measured. The movement patterns of whales were determined by observations of whale-surfacing positions.

Radio Frequency Identification (RFID) technology applied to the definition of underwater and subaerial coarse sediment movement

NASA Astrophysics Data System (ADS)

Bertoni, Duccio; Sarti, Giovanni; Benelli, Giuliano; Pozzebon, Alessandro; Raguseo, Gianluca

2010-07-01

In this paper, Radio Frequency Identification technology has been applied to track both underwater and subaerial displacement of pebbles along an artificial coarse beach at Marina di Pisa, Italy. Several preliminary laboratory tests have been performed to adapt the RFID technique for underwater use, which has been the primary impediment to this promising approach to the study of coarse sediment transport and movement. Tests showed the reliability of low frequencies for this kind of work, since they enable good signal transmission and reception through water. Passive ABS plastic transponders were inserted into about 100 pebbles and released onto the beach in March, 2009. A CORE-125 reader was chosen as the operating antenna to continuously transmit low frequency (125 kHz) signals. An acoustic signal toned whenever a pebble was detected while the unambiguous identification code of the pebble is shown immediately on the screen of a laptop connected to the reader. The positions of the pebbles were recorded with a total station. After two months (May, 2009), 74 marked pebbles were retrieved, 77% of the total. The positions of the retrieved pebbles were also recorded with the total station, thus allowing calculation of the coarse sediment transport tendency. About 60% of the recovered pebbles (44 out of 74) were found on the upper shoreface. The analysis of the marked pebble trajectories revealed a divergent transport movement in the northernmost sector of the beach. This movement was probably triggered by an irregularity of the submerged breakwater fronting the shoreline. The southern sector is characterised by chaotic pathways related to the formation and evolution of beach cusps. This outcome highlights and confirms the importance of a complete definition of the beach system, with no separation between the underwater and the subaerial portion of the shore when it comes to sediment transport and movement. This successful application of RFID technology to the underwater environment provides a chance to broaden understanding of a topic in need of further study.

Acute and long-term behavioral correlates of underwater trauma--potential relevance to stress and post-stress syndromes.

PubMed

Richter-Levin, G

1998-06-02

As a consequence of a brief but significantly extreme stressor, an individual will experience a stress response, which may sometimes develop into Acute Stress Disorder (ASD) or Post-Traumatic Stress Disorder (PTSD). Though a rat model for ASD and PTSD is not expected to encompass the richness and complexity of the disorders in humans, it will enable the study of the common underlying mechanisms that generate the disorders, the study of pre-trauma etiological aspects of the disorders and the screening of drugs with potential relevance to the treatment of the disorders. One well-documented aspect of PTSD is the enhancing influence of contextual elements on the appearance of symptoms of the post-stress trauma. To exploit this effect, we have chosen to assess the effects of an underwater trauma in the Morris water maze since the effects of such trauma on memory and attention can be later evaluated in the context of the trauma. At both 1 h and 3 weeks after the trauma, significant behavioral deficits were observed in the water maze. The effects of the underwater trauma on the performance of rats in the water maze were context specific. Underwater trauma in a different (out-of-context) water container had no effects on the ability of rats to perform a spatial memory task in the water maze. An elevated level of anxiety was found in the plus maze test, independently of whether the trauma was performed in the water maze or in a different (out-of-context) water container. The results indicate that a within-context underwater trauma has both acute and lasting behavioral consequences which can be assessed using a spatial memory test in the context of the trauma. The results are discussed in relation to their relevance to stress and PTSD.

Influence of multiple-passes on microstructure and mechanical properties of Al-Mg/SiC surface composites fabricated via underwater friction stir processing

NASA Astrophysics Data System (ADS)

Srivastava, Manu; Rathee, Sandeep; Maheshwari, Sachin; Siddiquee, Arshad Noor

2018-06-01

Friction stir processing (FSP) is a relatively newly developed solid-state process involving surface modifications for fabricating metal matrix surface composites. Obtaining metal matrix nano-composites with uniform dispersion of reinforcement particles via FSP route is an intricate task to accomplish. In this work, AA5059/SiC nano surface composites (SCs) were developed. Effect of multiple FSP passes and SiC addition on microstructure and mechanical properties of fabricated SCs during underwater condition was investigated. Results reflected that the average microhardness value of base metal (BM) increases from 85 Hv to 159 Hv in stir zone of four pass underwater friction stir processed (FSPed) SC. Highest ultimate tensile strength (UTS) achieved during four pass FSPed sample was 377 MPa that is higher than UTS of BM (321 MPa) and four pass FSPed sample developed at ambient air FSP conditions (347 MPa). An appreciably narrower heat affected zone is obtained owing to fast cooling and reduced heat conduction during underwater FSP, amounting to higher UTS as compared to BM and SC at ambient conditions. Thus, it can be concluded that surrounding medium and number of FSP passes have significant impact on mechanical properties of fabricated SCs. Analysis of microstructures and distribution of SiC particles in fabricated SCs were studied by optical microscope and FESEM respectively and found in good corroboration with the mechanical properties.

46 CFR 167.05-40 - Underwater survey.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's underwater...

46 CFR 167.05-40 - Underwater survey.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's underwater...

46 CFR 167.05-40 - Underwater survey.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's underwater...

46 CFR 167.05-40 - Underwater survey.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's underwater...

46 CFR 167.05-40 - Underwater survey.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's underwater...

Network Computing for Distributed Underwater Acoustic Sensors

DTIC Science & Technology

2014-03-31

underwater sensor network with mobility. In preparation. [3] EvoLogics (2013), Underwater Acoustic Modems, (Product Information Guide... Wireless Communications, 9(9), 2934–2944. [21] Pompili, D. and Akyildiz, I. (2010), A multimedia cross-layer protocol for underwater acoustic sensor networks ... Network Computing for Distributed Underwater Acoustic Sensors M. Barbeau E. Kranakis

Communications system for zero-g simulation tests in water

NASA Technical Reports Server (NTRS)

Smith, H. E.

1971-01-01

System connects seven observers, diver, and spare station, and utilizes public address system with underwater speakers to provide two-way communications between test subject and personnel in control of life support, so that test personnel are warned immediately of malfunction in pressure suit or equipment.

Multibeam 3D Underwater SLAM with Probabilistic Registration.

PubMed

Palomer, Albert; Ridao, Pere; Ribas, David

2016-04-20

This paper describes a pose-based underwater 3D Simultaneous Localization and Mapping (SLAM) using a multibeam echosounder to produce high consistency underwater maps. The proposed algorithm compounds swath profiles of the seafloor with dead reckoning localization to build surface patches (i.e., point clouds). An Iterative Closest Point (ICP) with a probabilistic implementation is then used to register the point clouds, taking into account their uncertainties. The registration process is divided in two steps: (1) point-to-point association for coarse registration and (2) point-to-plane association for fine registration. The point clouds of the surfaces to be registered are sub-sampled in order to decrease both the computation time and also the potential of falling into local minima during the registration. In addition, a heuristic is used to decrease the complexity of the association step of the ICP from O(n2) to O(n) . The performance of the SLAM framework is tested using two real world datasets: First, a 2.5D bathymetric dataset obtained with the usual down-looking multibeam sonar configuration, and second, a full 3D underwater dataset acquired with a multibeam sonar mounted on a pan and tilt unit.

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.

Underwater Wireless Sensor Networks: how do acoustic propagation models impact the performance of higher-level protocols?

PubMed

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.

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

Results and applications of a space suit range-of-motion study

NASA Technical Reports Server (NTRS)

Reinhardt, AL

1989-01-01

The range of motion of space suits has traditionally been described using limited 2-D mapping of limb, torso, or arm movements performed in front of an orthogonal grid. A new technique for recovering extra-vehicular (EVA) space suit range-of-motion data during underwater testing was described in a paper presented by the author at the 1988 conference. The new technique uses digitized data which is automatically acquired from video images of the subject. Three-dimensional trajectories are recovered from these data, and can be displayed using 2-D computer graphics. Results of using this technique for the current shuttle EVA suit during underwater simulated weightlessness testing are discussed. Application of the data for use in animating anthropometric computer models is highlighted.

Inertial sensor self-calibration in a visually-aided navigation approach for a micro-AUV.

PubMed

Bonin-Font, Francisco; Massot-Campos, Miquel; Negre-Carrasco, Pep Lluis; Oliver-Codina, Gabriel; Beltran, Joan P

2015-01-16

This paper presents a new solution for underwater observation, image recording, mapping and 3D reconstruction in shallow waters. The platform, designed as a research and testing tool, is based on a small underwater robot equipped with a MEMS-based IMU, two stereo cameras and a pressure sensor. The data given by the sensors are fused, adjusted and corrected in a multiplicative error state Kalman filter (MESKF), which returns a single vector with the pose and twist of the vehicle and the biases of the inertial sensors (the accelerometer and the gyroscope). The inclusion of these biases in the state vector permits their self-calibration and stabilization, improving the estimates of the robot orientation. Experiments in controlled underwater scenarios and in the sea have demonstrated a satisfactory performance and the capacity of the vehicle to operate in real environments and in real time.

Inertial Sensor Self-Calibration in a Visually-Aided Navigation Approach for a Micro-AUV

PubMed Central

Bonin-Font, Francisco; Massot-Campos, Miquel; Negre-Carrasco, Pep Lluis; Oliver-Codina, Gabriel; Beltran, Joan P.

2015-01-01

This paper presents a new solution for underwater observation, image recording, mapping and 3D reconstruction in shallow waters. The platform, designed as a research and testing tool, is based on a small underwater robot equipped with a MEMS-based IMU, two stereo cameras and a pressure sensor. The data given by the sensors are fused, adjusted and corrected in a multiplicative error state Kalman filter (MESKF), which returns a single vector with the pose and twist of the vehicle and the biases of the inertial sensors (the accelerometer and the gyroscope). The inclusion of these biases in the state vector permits their self-calibration and stabilization, improving the estimates of the robot orientation. Experiments in controlled underwater scenarios and in the sea have demonstrated a satisfactory performance and the capacity of the vehicle to operate in real environments and in real time. PMID:25602263

Fusion and Gaussian mixture based classifiers for SONAR data

NASA Astrophysics Data System (ADS)

Kotari, Vikas; Chang, KC

2011-06-01

Underwater mines are inexpensive and highly effective weapons. They are difficult to detect and classify. Hence detection and classification of underwater mines is essential for the safety of naval vessels. This necessitates a formulation of highly efficient classifiers and detection techniques. Current techniques primarily focus on signals from one source. Data fusion is known to increase the accuracy of detection and classification. In this paper, we formulated a fusion-based classifier and a Gaussian mixture model (GMM) based classifier for classification of underwater mines. The emphasis has been on sound navigation and ranging (SONAR) signals due to their extensive use in current naval operations. The classifiers have been tested on real SONAR data obtained from University of California Irvine (UCI) repository. The performance of both GMM based classifier and fusion based classifier clearly demonstrate their superior classification accuracy over conventional single source cases and validate our approach.

Explosives detection in the marine environment using UUV-modified immunosensor

NASA Astrophysics Data System (ADS)

Charles, Paul T.; Adams, André A.; Deschamps, Jeffrey R.; Veitch, Scott P.; Hanson, Alfred; Kusterbeck, Anne W.

2011-05-01

Port and harbor security has rapidly become a point of interest and concern with the emergence of new improvised explosive devices (IEDs). The ability to provide physical surveillance and identification of IEDs and unexploded ordnances (UXO) at these entry points has led to an increased effort in the development of unmanned underwater vehicles (UUVs) equipped with sensing devices. Traditional sensors used to identify and locate potential threats are side scan sonar/acoustic methods and magnetometers. At the Naval Research Laboratory (NRL), we have developed an immunosensor capable of detecting trace levels of explosives that has been integrated into a REMUS payload for use in the marine environment. Laboratory tests using a modified PMMA microfluidic device with immobilized monoclonal antibodies specific for TNT and RDX have been conducted yielding detection levels in the low parts-per-billion (ppb) range. New designs and engineered improvements in microfluidic devices, fluorescence signal probes, and UUV internal fluidic and optical components have been investigated and integrated into the unmanned underwater prototype. Results from laboratory and recent field demonstrations using the prototype UUV immunosensor will be discussed. The immunosensor in combination with acoustic and other sensors could serve as a complementary characterization tool for the detection of IEDs, UXOs and other potential chemical or biological threats.

The effect of traveling wave shapes in the maneuver control and efficiency of an underwater robot propelled by an undulating fin

NASA Astrophysics Data System (ADS)

Liu, Hanlin; Curet, Oscar

2016-11-01

Effective control of propulsive undulating fins has the potential to enhance the maneuverability and efficiency of underwater vehicles allowing them to navigate in more complex environments. Aquatic animals using this type of propulsion are able to perform complex maneuvers by sending different traveling waves along one or multiple elongated fins. Recent work has investigated the propulsive forces, the hydrodynamics and the efficiency of an undulating ribbon fin. However, it is still not understood how different traveling wave shapes along the fin can be used to control the hydrodynamic forces and torques to perform different maneuvers. In this work, we study the effect of traveling wave shapes on the hydrodynamic forces and torques, swimming speed, maneuver control and propulsive performance of an underwater vehicle propelled by an undulating fin. The underwater robot propels by actuating a fin that is composed of sixteen independent rays interconnected with a flexible membrane. The hull contains all the electronics, batteries, motors and sensors. The underwater vehicle was tested in a water tank-flume facility. In a series of experiments, we measured the motion of the vessel and the power consumption for different traveling wave patterns. In addition, we measured the flow around the fin using Particle Image Velocimetry. We present the results concerning the power distribution along the fin, propulsive efficiency, free-swimming speed and pitch control based on different fin kinematics. National Science Foundation under Grant No. 1420774.

Results of EVA/mobile transporter space station truss assembly tests

NASA Technical Reports Server (NTRS)

Watson, Judith J.; Heard, Walter L., Jr.; Bush, Harold G.; Lake, M. S.; Jensen, J. K.; Wallsom, R. E.; Phelps, J. E.

1988-01-01

Underwater neutral buoyance tests were conducted to evaluate the use of a Mobile Transporter concept in conjunction with EVA astronauts to construct the Space Station Freedom truss structure. A three-bay orthogonal tetrahedral truss configuration with a 15 foot square cross section was repeatedly assembled by a single pair of pressure suited test subjects working from the Mobile Transporter astronaut positioning devices (mobile foot restraints). The average unit assembly time (which included integrated installation of utility trays) was 27.6 s/strut, or 6 min/bay. The results of these tests indicate that EVA assembly of space station size structures can be significantly enhanced when using a Mobile Transporter equipped with astronaut positioning devices. Rapid assembly time can be expected and are dependent primarily on the rate of translation permissible for on-orbit operations. The concept used to demonstate integrated installation of utility trays requires minimal EVA handling and consequentially, as the results show, has little impact on overall assembly time.

New Explorer-class AUV Ready for Deep-water, High-resolution Habitat Mapping Studies

NASA Astrophysics Data System (ADS)

Potts, T. A.; Shepard, A.

2006-12-01

In 2002, a partnership was formed to design, construct, field test, and operate an Autonomous Underwater Vehicle (AUV) equipped to provide high-resolution (<1 m) maps of offshore seafloor habitats down to 2200 meters depth. An ISE Explorer-class AUV was constructed and equipped to conduct seafloor characterization via multi-beam EM2000 providing both bathymetry and backscatter. Three 10-day cruises will be conducted between August and November 2006 to put the vehicle through its paces and refine operating protocols. It is anticipated that the vehicle will log over 200 hours of bottom time and acquire over 30 GB of data at proposed marine protected area sites off North and South Carolina, Gray's Reef National Marine Sanctuary off Georgia, and at the Oculina Habitat Area of Particular Concern off the east coast of Florida. The AUV will begin supporting competitively reviewed science projects starting in 2007.

Drying results of K-Basin fuel element 1990 (Run 1)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marschman, S.C.; Abrefah, J.; Klinger, G.S.

1998-06-01

The water-filled K-Basins in the Hanford 100-Area have been used to store N-Reactor spent nuclear fuel (SNF) since the 1970s. Because some leaks in the basins have been detected and some of the fuel is breached due to handling damage and corrosion, efforts are underway to remove the fuel elements from wet storage. An Integrated Process Strategy (IPS) has been developed to package, dry, transport, and store these metallic uranium fuels in an interim storage facility on the Hanford Site (WHC 1995). Information required to support the development of the drying processes, and the required safety analyses, is being obtainedmore » from characterization tests conducted on fuel elements removed from the K-Basins. A series of whole element drying tests (reported in separate documents, see Section 8.0) have been conducted by Pacific Northwest National Laboratory (PNNL) on several intact and damaged fuel elements recovered from both the K-East and K-West Basins. This report documents the results of the first of those tests (Run 1), which was conducted on an N-Reactor inner fuel element (1990) that had been stored underwater in the K-West Basin (see Section 2.0). This fuel element was subjected to a combination of low- and high-temperature vacuum drying treatments that were intended to mimic, wherever possible, the fuel treatment strategies of the IPS. The testing was conducted in the Whole Element Furnace Testing System, described in Section 3.0, located in the Postirradiation Testing Laboratory (PTL, 327 Building). The test conditions and methodology are given in Section 4.0, and the experimental results provided in Section 5.0. These results are further discussed in Section 6.0.« less

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.

Blue Laser Diode Enables Underwater Communication at 12.4 Gbps

PubMed Central

Wu, Tsai-Chen; Chi, Yu-Chieh; Wang, Huai-Yung; Tsai, Cheng-Ting; Lin, Gong-Ru

2017-01-01

To enable high-speed underwater wireless optical communication (UWOC) in tap-water and seawater environments over long distances, a 450-nm blue GaN laser diode (LD) directly modulated by pre-leveled 16-quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) data was employed to implement its maximal transmission capacity of up to 10 Gbps. The proposed UWOC in tap water provided a maximal allowable communication bit rate increase from 5.2 to 12.4 Gbps with the corresponding underwater transmission distance significantly reduced from 10.2 to 1.7 m, exhibiting a bit rate/distance decaying slope of −0.847 Gbps/m. When conducting the same type of UWOC in seawater, light scattering induced by impurities attenuated the blue laser power, thereby degrading the transmission with a slightly higher decay ratio of 0.941 Gbps/m. The blue LD based UWOC enables a 16-QAM OFDM bit rate of up to 7.2 Gbps for transmission in seawater more than 6.8 m. PMID:28094309

On the coupling of nonlinear macro-fiber composite piezoelectric cantilever dynamics with hydrodynamic loads

NASA Astrophysics Data System (ADS)

Tan, D.; Erturk, A.

2018-03-01

For bio-inspired, fish-like robotic propulsion, the Macro-Fiber Composite (MFC) piezoelectric technology offers noiseless actuation with a balance between actuation force and velocity response. However, internal nonlinear- ities within the MFCs, such as piezoelectric softening, geometric hardening, inertial softening, and nonlinear dissipation, couple with the hydrodynamic loading on the structure from the surrounding fluid. In the present work, we explore nonlinear actuation of MFC cantilevers underwater and develop a mathematical framework for modeling and analysis. In vacuo resonant actuation experiments are conducted for a set of MFC cantilevers of varying length to width aspect ratios to validate the structural model in the absence of fluid loading. These MFC cantilevers are then subjected to underwater resonant actuation experiments, and model simulations are compared with nonlinear experimental frequency response functions. It is observed that semi-empirical hydro- dynamic loads obtained from quasilinear experiments have to be modified to account for amplitude dependent added mass, and additional nonlinear hydrodynamic effects might be present, yielding qualitative differences in the resulting underwater frequency respones curves with increased excitation amplitude.

Annotated Bibliography of Psychomotor Testing.

DTIC Science & Technology

1987-03-01

of observation and comparison were administered four times in one week to 394 adolescent boys enrolled in a trade school. Observations and subjective...44 Time Production Test: 15 Torque Test: 48,49,64,65 Tremor: 2 U Underwater depth, effects of: 2,3,11 U.S. Employment Service Pegboard: 16 V Videogame

Methods and Systems for Configuring Sensor Acquisition Based on Pressure Steps

NASA Technical Reports Server (NTRS)

DeDonato, Mathew (Inventor)

2015-01-01

Technologies are provided for underwater measurements. A system includes an underwater vessels including: a plurality of sensors disposed thereon for measuring underwater properties; and a programmable controller configured to selectively activate the plurality of sensors based at least in part on underwater pressure. A user may program at what pressure ranges certain sensors are activated to measure selected properties, and may also program the ascent/descent rate of the underwater vessel, which is correlated with the underwater pressure.

A Strategy to employ coordinated, autonomous Platforms for addressing long-term biochemical observing Tasks

NASA Astrophysics Data System (ADS)

Waldmann, H. C.; Montenegro, S.

2016-02-01

Autonomous platforms get a growing importance for ocean observing tasks in particular to enable long-term observing tasks. Employing the mobility of those platforms allows a targeted investigations of phenomena that up to now are mainly seen from satellite but are lacking detailed scrutiny. As part oft he national funded project ROBEX new operation concepts for mobile platforms are developed in particular a new type of underwater glider with larger payload capacity compared to legacy systems will be developed. First tests in the pool of a aparticular hull shape have led to a better understanding oft he hydrodynamic condition and an optomized hull design was derived from that. The WAVEGLIDER system of Liquid Robotics lends itsself to be used as a communication hub and a platform to track underwater vehicles. Therefore the combination of those systems are currently assessed in regard to a possible operation and its hard- and software implementation. A major issue ist o achieve a coordinated displacement of these completely decoupled systems. Issues on how to mitigate faulty mission runs, coping with low communication bandwidths, and ensuring adequate positioning information about the underwater glider have to be addressed. Robotic concepts known from terrestrial applications like for UAV systems are tested under the more stringent environmental conditions in ocean waters. With this combination of WAVEGLIDER and underwater glider it is planned to carry out long-term missions to investigate biochemical processes in the water column in particular to investigate the particle transport through the water column and the processes resulting from that. Concepts and first results of those tasks will be presented.

Optimal Scheduling for Underwater Communications in Multiple-user Scenarios

DTIC Science & Technology

2014-09-30

underwater acoustic sensor networks . These techniques aim at consuming as less energy as... underwater acoustic networks disrupt the behavior of surrounding species of marine mammals. As a consequence of these two studies, we aim at developing...Markov models of incremental redundancy hybrid ARQ over underwater acoustic channels. Elsevier Journal on Ad-hoc Networks (Special Issue on Underwater Communications and Networks ), 2014. 4

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

DTIC Science & Technology

2014-09-30

underwater acoustic communication technologies for autonomous distributed underwater networks , through innovative signal processing, coding, and...4. TITLE AND SUBTITLE Advancing Underwater Acoustic Communication for Autonomous Distributed Networks via Sparse Channel Sensing, Coding, and...coding: 3) OFDM modulated dynamic coded cooperation in underwater acoustic channels; 3 Localization, Networking , and Testbed: 4) On-demand

Selective increase in the association of the β2 adrenergic receptor, β Arrestin-1 and p53 with Mdm2 in the ventral hippocampus one month after underwater trauma.

PubMed

Sood, Rapita; Ritov, Gilad; Richter-Levin, Gal; Barki-Harrington, Liza

2013-03-01

Chronic infusion of mice with a β2 adrenergic receptor (β2AR) analog was shown to cause long-term DNA damage in a pathway which involves β Arresin-1-mediated activation of Mdm2 and subsequent degradation of the tumor suppressor protein p53. The objective of the present study was to test whether a single acute stress, which manifests long lasting changes in behavior, affects the interaction of Mdm2 with p53, β2AR, and β Arrestin-1 in the dorsal and ventral hippocampal CA1. Adult rats were subject to underwater trauma, a brief forceful submersion under water and tested a month later for behavioral and biochemical changes. Elevated plus maze tests confirmed that animals that experienced the threat of drowning present heightened levels of anxiety one month after trauma. An examination of the CA1 hippocampal areas of the same rats showed that underwater trauma caused a significant increase in the association of Mdm2 with β2AR, β Arrestin-1, and p53 in the ventral but not dorsal CA1. Our results provide support for the idea that stress-related events may result in biochemical changes restricted to the ventral 'emotion-related' parts of the hippocampus. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous adaptation to size, distance, and curvature underwater.

PubMed

Vernoy, M W

1989-02-01

Perceptual adaptation to underwater size, distance, and curvature distortion was measured for four different adaptation conditions. These conditions consisted of (a) playing Chinese checkers underwater, (b) swimming with eyes open underwater, (c) viewing a square underwater, and (d) an air control. Significant adaptation to underwater distortions was recorded in all except the air control condition. In the viewing square condition a positive correlation between size and distance adaptation was noted. It was suggested that adaptation to curvature may have mediated the positive correlation. Possible applications for the training of divers are discussed.

Reef Sound as an Orientation Cue for Shoreward Migration by Pueruli of the Rock Lobster, Jasus edwardsii

PubMed Central

Green, Bridget S.; Gardner, Caleb; Hesse, Jan; Stanley, Jenni A.

2016-01-01

The post-larval or puerulus stage of spiny, or rock, lobsters (Palinuridae) swim many kilometres from open oceans into coastal waters where they subsequently settle. The orientation cues used by the puerulus for this migration are unclear, but are presumed to be critical to finding a place to settle. Understanding this process may help explain the biological processes of dispersal and settlement, and be useful for developing realistic dispersal models. In this study, we examined the use of reef sound as an orientation cue by the puerulus stage of the southern rock lobster, Jasus edwardsii. Experiments were conducted using in situ binary choice chambers together with replayed recording of underwater reef sound. The experiment was conducted in a sandy lagoon under varying wind conditions. A significant proportion of puerulus (69%) swam towards the reef sound in calm wind conditions. However, in windy conditions (>25 m s-1) the orientation behaviour appeared to be less consistent with the inclusion of these results, reducing the overall proportion of pueruli that swam towards the reef sound (59.3%). These results resolve previous speculation that underwater reef sound is used as an orientation cue in the shoreward migration of the puerulus of spiny lobsters, and suggest that sea surface winds may moderate the ability of migrating pueruli to use this cue to locate coastal reef habitat to settle. Underwater sound may increase the chance of successful settlement and survival of this valuable species. PMID:27310676

Reef Sound as an Orientation Cue for Shoreward Migration by Pueruli of the Rock Lobster, Jasus edwardsii.

PubMed

Hinojosa, Ivan A; Green, Bridget S; Gardner, Caleb; Hesse, Jan; Stanley, Jenni A; Jeffs, Andrew G

2016-01-01

The post-larval or puerulus stage of spiny, or rock, lobsters (Palinuridae) swim many kilometres from open oceans into coastal waters where they subsequently settle. The orientation cues used by the puerulus for this migration are unclear, but are presumed to be critical to finding a place to settle. Understanding this process may help explain the biological processes of dispersal and settlement, and be useful for developing realistic dispersal models. In this study, we examined the use of reef sound as an orientation cue by the puerulus stage of the southern rock lobster, Jasus edwardsii. Experiments were conducted using in situ binary choice chambers together with replayed recording of underwater reef sound. The experiment was conducted in a sandy lagoon under varying wind conditions. A significant proportion of puerulus (69%) swam towards the reef sound in calm wind conditions. However, in windy conditions (>25 m s-1) the orientation behaviour appeared to be less consistent with the inclusion of these results, reducing the overall proportion of pueruli that swam towards the reef sound (59.3%). These results resolve previous speculation that underwater reef sound is used as an orientation cue in the shoreward migration of the puerulus of spiny lobsters, and suggest that sea surface winds may moderate the ability of migrating pueruli to use this cue to locate coastal reef habitat to settle. Underwater sound may increase the chance of successful settlement and survival of this valuable species.

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

AURP: an AUV-aided underwater routing protocol for underwater acoustic sensor networks.

PubMed

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.

76 FR 4529 - Safety Zone; Underwater Hazard, Gravesend Bay, Brooklyn, NY

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-26

... divers, U.S. Navy Explosive Ordnance Disposal divers from Naval Weapons Station Earle conducted... Government and Indian tribes. Energy Effects We have analyzed this rule under Executive Order 13211, Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use. We have determined that...

Airborne Lidar Bathymetry Beam Diagnostics Using an Underwater Optical Detector Array

NASA Astrophysics Data System (ADS)

Birkebak, Matthew

The surface geometry of air-water interface is considered as an important factor affecting the performance of Airborne Lidar Bathymetry (ALB), and laser optical communication through the water surface. ALB is a remote sensing technique that utilizes a pulsed green (532 nm) laser mounted to an airborne platform in order to measure water depth. The water surface (i.e., air-water interface) can distort the light beam's ray-path geometry and add uncertainty to range calculation measurements. Previous studies on light refracting through a complex water surface are heavily dependent on theoretical models and simulations. In addition, only very limited work has been conducted to validate these theoretical models using experiments under well-controlled laboratory conditions. The goal of the study is to establish a clear relationship between water-surface conditions and the uncertainty of ALB measurement. This relationship will be determined by conducting more extensive empirical measurements to characterize the changes in beam slant path associated with a variety of short wavelength wind ripples, typically seen in ALB survey conditions. This study will focus on the effects of capillary and gravity-capillary waves with surface wavelengths smaller than the diameter of the laser beam on the water surface. Simulations using Monte-Carlo techniques of the ALB beam footprints and the environmental conditions were used to analyze the ray-path geometries. Based on the simulation results, laboratory experiments were then designed to test key parameters that have the greatest contribution on beam path and direction through the water. The laser beam dispersion experiments were conducted in well-controlled laboratory setting at the University of New Hampshire's Wave and Tow tank. The spatial elevations of the water surface were independently measured using a high resolution wave staff. The refracted laser beam footprint was measured using an underwater optical detector consisting of a 6x6 array of photodiodes. Image processing techniques were used to estimate the laser's incidence angle intercepted by the detector array. Beam patterns that resulted from intersection between the laser beam light field underwater and the detector array were modeled and used to calculate changes in position and orientation for water surface conditions containing wavelengths less than 0.1m. Finally, a total horizontal uncertainty (THU) model was estimated, which can be implemented in total propagated uncertainty (TPU) models for reporting as a measure of the quality of each measurement. The wave refraction error for various sea states and beam characteristics was successfully quantified using both experimental and analytical techniques.

Vehicle Based Vector Sensor

DTIC Science & Technology

2015-09-28

buoyant underwater vehicle with an interior space in which a length of said underwater vehicle is equal to one tenth of the acoustic wavelength...underwater vehicle with an interior space in which a length of said underwater vehicle is equal to one tenth of the acoustic wavelength; an...unmanned underwater vehicle that can function as an acoustic vector sensor. (2) Description of the Prior Art [0004] It is known that a propagating

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.

Auditory and behavioral responses of California sea lions (Zalophus californianus) to single underwater impulses from an arc-gap transducer.

PubMed

Finneran, James J; Dear, Randall; Carder, Donald A; Ridgway, Sam H

2003-09-01

A behavioral response paradigm was used to measure underwater hearing thresholds in two California sea lions (Zalophus californianus) before and after exposure to underwater impulses from an arc-gap transducer. Preexposure and postexposure hearing thresholds were compared to determine if the subjects experienced temporary shifts in their masked hearing thresholds (MTTS). Hearing thresholds were measured at 1 and 10 kHz. Exposures consisted of single underwater impulses produced by an arc-gap transducer referred to as a "pulsed power device" (PPD). The electrical charge of the PPD was varied from 1.32 to 2.77 kJ; the distance between the subject and the PPD was varied over the range 3.4 to 25 m. No MTTS was observed in either subject at the highest received levels: peak pressures of approximately 6.8 and 14 kPa, rms pressures of approximately 178 and 183 dB re: 1 microPa, and total energy fluxes of 161 and 163 dB re: 1 microPa2s for the two subjects. Behavioral reactions to the tests were observed in both subjects. These reactions primarily consisted of temporary avoidance of the site where exposure to the PPD impulse had previously occurred.

Experimental findings on the underwater measurements uncertainty of speed of sound and the alignment system

NASA Astrophysics Data System (ADS)

Santos, T. Q.; Alvarenga, A. V.; Oliveira, D. P.; Mayworm, R. C.; Souza, R. M.; Costa-Félix, R. P. B.

2016-07-01

Speed of sound is an important quantity to characterize reference materials for ultrasonic applications, for instance. The alignment between the transducer and the test body is an key activity in order to perform reliable and consistent measurement. The aim of this work is to evaluate the influence of the alignment system to the expanded uncertainty of such measurement. A stainless steel cylinder was previously calibrated on an out of water system typically used for calibration of non-destructive blocks. Afterwards, the cylinder was calibrated underwater with two distinct alignment system: fixed and mobile. The values were statistically compared to the out-of-water measurement, considered the golden standard for such application. For both alignment systems, the normalized error was less than 0.8, leading to conclude that the both measurement system (under and out-of-water) do not diverge significantly. The gold standard uncertainty was 2.7 m-s-1, whilst the fixed underwater system resulted in 13 m-s-1, and the mobile alignment system achieved 6.6 m-s-1. After the validation of the underwater system for speed of sound measurement, it will be applied to certify Encapsulated Tissue Mimicking Material as a reference material for biotechnology application.

Comparison of PAM Systems for Acoustic Monitoring and Further Risk Mitigation Application.

PubMed

Ludwig, Stefan; Kreimeyer, Roman; Knoll, Michaela

2016-01-01

We present results of the SIRENA 2011 research cruises conducted by the NATO Undersea Research Centre (NURC) and joined by the Research Department for Underwater Acoustics and Geophysics (FWG), Bundeswehr Technical Centre (WTD 71) and the Universities of Kiel and Pavia. The cruises were carried out in the Ligurian Sea. The main aim of the FWG was to test and evaluate the newly developed towed hydrophone array as a passive acoustic monitoring (PAM) tool for risk mitigation applications. The system was compared with the PAM equipment used by the other participating institutions. Recorded sounds were used to improve an automatic acoustic classifier for marine mammals, and validated acoustic detections by observers were compared with the results of the classifier.

KSC-03PD-2383

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin monitor some of the project's equipment just released into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2380

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepare to release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2385

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin lifts some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2382

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin releases some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2378

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepares some of the project's equipment for placement in the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2386

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin secure some of the project's equipment back into the vessel. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

Influence of long-range forces and capillarity on the function of underwater superoleophobic wrinkled surfaces.

PubMed

Owais, Ahmed; Smith-Palmer, Truis; Gentle, Angus; Neto, Chiara

2018-06-26

Underwater superoleophobic surfaces can be considered a particular type of lubricant-infused surface, that have anti-fouling properties by virtue of a trapped water layer that repels oils. However, as their function relies on a water layer being trapped in the surface roughness, it is crucial to understand the factors that determine the layer stability. In this work, the forces that are responsible for the stability of thin liquid films within structured surfaces were quantified, and the conclusions were tested against the performance of wrinkled surfaces as underwater superoleophobic coatings. Here, the system studied was a family of wrinkled surfaces made of hydrophilic poly(4-vinylpyridine) (P4VP), whereby the wrinkle width could be controllably tuned in the range 90 nm to 8000 nm. The van der Waals free energy was quantified and the capillary forces trapping water in the surface micro- and nano-wrinkle structure were estimated. P4VP surfaces with micro-scale wrinkles had underwater superoleophobic properties, and low adhesion to different oils with droplet roll-off angle below 6° ± 1°. Despite the van der Waals free energy of the system pointing to the dewetting of a water film under oil on top of a smooth P4VP film, the wrinkled structure is sufficient to induce a Cassie state with a trapped water layer. The micro-scale wrinkles (average width 4-12 μm) were found to be particularly effective in the trapping of the water in a Cassie non-adhesive state. The P4VP wrinkled surfaces are superamphiphobic, as when they were first infused with oil, and then exposed to a droplet of water under oil, they exhibited superhydrophobic behavior. The P4VP wrinkles have the additional useful feature of being transparent underwater, which makes them useful candidates for the protection of underwater cameras and sensors.

Survey and Recording Technologies in Italian Underwater Cultural Heritage: Research and Public Access Within the Framework of the 2001 UNESCO Convention

NASA Astrophysics Data System (ADS)

Secci, Massimiliano

2017-08-01

The 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage is slowly but peremptorily becoming a standard reference tool for underwater archaeology and underwater cultural heritage management. The many provisions included within the Convention touch on many aspects that are key to an effective protection and promotion of the underwater cultural heritage. Within the web of these provisions many aspects are gaining consideration and driving research in underwater archaeology worldwide. These provisions, when seen within a wider frame of social, economical and technological dynamics, pinpoint many aspects requiring further scrutiny from the disciplinary circle. In the framework of the 2001 UNESCO Convention, this article will analyze the path traveled in technological acquisition in the practice of Italian underwater archaeology and how this has affected the approach to underwater cultural heritage management, particularly highlighting how this process has been further influenced by the adoption in 2001 of the Convention and Italy's ratification of it in 2010.

An Interdisciplinary Field Robotics Program for Undergraduate Computer Science and Engineering Education

ERIC Educational Resources Information Center

Kitts, Christopher; Quinn, Neil

2004-01-01

Santa Clara University's Robotic Systems Laboratory conducts an aggressive robotic development and operations program in which interdisciplinary teams of undergraduate students build and deploy a wide range of robotic systems, ranging from underwater vehicles to spacecraft. These year-long projects expose students to the breadth of and…

Advanced Geophysical Classification with the Marine Towed Array

NASA Astrophysics Data System (ADS)

Steinhurst, D.; Harbaugh, G.; Keiswetter, D.; Bell, T. W.; Massey, G.; Wright, D.

2017-12-01

The Marine Towed Array, or MTA, is an underwater dual-mode sensor array that has been successfully deployed at multiple marine venues in support of Strategic Environmental Research and Development Program (SERDP) and Environmental Security Technology Certification Program (ESTCP) demonstrations beginning in 2004. It provided both marine electromagnetic and marine magnetic sensors for detection and mapping of underwater UXO. The EMI sensor array was based on older technology, which in several ESTCP demonstrations has not been able to support advanced geophysical classification (AGC). Under ESTCP funding, the U.S. Naval Research Laboratory is in the process of upgrading the MTA with modern, advanced electromagnetic (EMI) electronics and replacing the sensor array with a modern, multistatic array design. A half-scale version of the proposed array has been built and tested on land. Six tri-axial receiver cubes were placed inside two- and three- transmit coil configurations in equivalent positions to design locations for the MTA wing. The responses of a variety of munitions items and test spheres were measured over a range of target-to-array geometries and in both static and simulated dynamic data collection modes. The multi-transmit coil configuration was shown to provide enhanced single-pass classification performance over the original single coil design, particularly as a function of target location relative to the centerline. The ability to go beyond anomaly detection and additionally classify detected anomalies from survey data would dramatically improve the state of the art for underwater UXO remediation by reducing costs and improving the efficiency of these efforts. The results of our efforts to return the MTA to service and validating the new EMI array's design for UXO detection and classification in the underwater environment will be the focus of this presentation.

The Effect of Underwater Imagery Radiometry on 3d Reconstruction and Orthoimagery

NASA Astrophysics Data System (ADS)

Agrafiotis, P.; Drakonakis, G. I.; Georgopoulos, A.; Skarlatos, D.

2017-02-01

The work presented in this paper investigates the effect of the radiometry of the underwater imagery on automating the 3D reconstruction and the produced orthoimagery. Main aim is to investigate whether pre-processing of the underwater imagery improves the 3D reconstruction using automated SfM - MVS software or not. Since the processing of images either separately or in batch is a time-consuming procedure, it is critical to determine the necessity of implementing colour correction and enhancement before the SfM - MVS procedure or directly to the final orthoimage when the orthoimagery is the deliverable. Two different test sites were used to capture imagery ensuring different environmental conditions, depth and complexity. Three different image correction methods are applied: A very simple automated method using Adobe Photoshop, a developed colour correction algorithm using the CLAHE (Zuiderveld, 1994) method and an implementation of the algorithm described in Bianco et al., (2015). The produced point clouds using the initial and the corrected imagery are then being compared and evaluated.

Assessment of Suited Reach Envelope in an Underwater Environment

NASA Technical Reports Server (NTRS)

Kim, Han; Benson, Elizabeth; Bernal, Yaritza; Jarvis, Sarah; Meginnis, Ian; Rajulu, Sudhakar

2017-01-01

Predicting the performance of a crewmember in an extravehicular activity (EVA) space suit presents unique challenges. The kinematic patterns of suited motions are difficult to reproduce in gravity. Additionally, 3-D suited kinematics have been practically and technically difficult to quantify in an underwater environment, in which crewmembers are commonly trained and assessed for performance. The goal of this study is to develop a hardware and software system to predictively evaluate the kinematic mobility of suited crewmembers, by measuring the 3-D reach envelope of the suit in an underwater environment. This work is ultimately aimed at developing quantitative metrics to compare the mobility of the existing Extravehicular Mobility Unit (EMU) to newly developed space suit, such as the Z-2. The EMU has been extensively used at NASA since 1981 for EVA outside the Space Shuttle and International Space Station. The Z-2 suit is NASA's newest prototype space suit. The suit is comprised of new upper torso and lower torso architectures, which were designed to improve test subject mobility.

An Underwater Target Detection System for Electro-Optical Imagery Data

DTIC Science & Technology

2010-06-01

detection and segmentation of underwater mine-like objects in the EO images captured with a CCD-based image sensor. The main focus of this research is to...develop a robust detection algorithm that can be used to detect low contrast and partial underwater objects from the EO imagery with low false alarm rate...underwater target detection I. INTRODUCTION Automatic detection and recognition of underwater objects from EO imagery poses a serious challenge due to poor

46 CFR 167.15-33 - Underwater Survey in Lieu of Drydocking (UWILD).

Code of Federal Regulations, 2010 CFR

2010-10-01

... SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Inspections § 167.15-33 Underwater Survey in Lieu of Drydocking (UWILD). (a) The Officer in Charge, Marine Inspection (OCMI), may approve an underwater survey instead of..., Marine Inspection submits a recommendation for future underwater surveys, the results of the hull gauging...

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…

Cardiorespiratory performance of coronary artery disease patients on land versus underwater treadmill tests: a comparative study.

PubMed

Garcia, Mauricio Koprowski; Rizzo, Limanara; Yazbek-Júnior, Paulo; Yutiyama, Daniela; Silva, Fabiola Jomar da; Matheus, Denise; Mastrocolla, Luiz Eduardo; Massad, Eduardo

2017-11-01

To compare responses to a cardiopulmonary exercise test on land versus on an underwater treadmill, to assess the cardiorespiratory performance of coronary artery disease patients while immersed in warm water and to compare with the performance of healthy individuals. The sample population consisted of 40 subjects, which included 20 coronary artery disease patients aged 63.7±8.89 years old, functional class I and II, according to the New York Hearth Association, and 20 healthy subjects aged 64.7±7.09 years old. The statistical significances were calculated through an ANOVA test with a (1 - β) power of 0.861. ClinicalTrials.gov: NCT00989248 (22). Significant differences were uncovered in coronary artery disease group regarding the variables heart beats (HB), (p>0.01), oxygen consumption (VO2), (p>0.01) and carbon dioxide production (VCO2) (p<0.01). Also, for the same group, in relation to the environment, water versus on land for HB, VO2, VCO2 and oxygen for each heart beat (VO2/HB) all of than (p<0.01). The stages for data collected featured the subject's performance throughout the experiment, and within the given context, variables rating of perceived exertion (RPE), HB, VO2, VCO2 and VO2/HB (p<0.01) showed significant interactions between test stages and environment. Additionally, there was a significant interaction between the etiology and the test stages for the variables HB, VO2 and VCO2 (p<0.01). Electrocardiographic changes compatible with myocardial ischemia or arrhythmia were not observed. The subjects exhibited lower scores on Borg's perceived exertion scale in the water than at every one of the test stages on land (p<0.01). This study show that a cardiopulmonary exercise test can be safely conducted in subjects in immersion and that the procedures, resources and equipment used yielded replicable and reliable data. Significant differences observed in water versus on land allow us to conclude that coronary artery disease patients are able to do physical exercise in water and that the physiological effects of immersion do not present any risk for such patients, as exercise was well tolerated by all subjects.

Estimates of the radiological dose to people living on Bikini Island for two weeks while diving in and around the sunken ships in Bikini Lagoon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robison, W.L.

1990-09-01

Bikini Island and Bikini Lagoon were contaminated by fallout from nuclear weapons tests conducted at the atoll by the United States from 1946 to 1958. The second test, Baker, of the Crossroads series was an underwater detonation in 1946 that sank several ships in the lagoon, including the USS Saratoga and the Japanese battleship Nagato. The ships received high-intensity gamma-ray and neutron bombardment from the Baker test, which induced radioactivity in the metal structures. Some of the tests conducted after the Baker shot (there were 21 tests in all) injected contaminated carbonate particles into the air, some of which weremore » deposited across the lagoon surface. Most of this contaminated soil then settled onto the ships` decks and other structures and on the lagoon bottom. These sunken ships provide an interesting location for divers. Recreational diving and swimming in and around the ships raises the question of the potential radiological dose from the radionuclides present in or on the ships and in the lagoon sediments. The purpose of this paper, therefore, is to present an analysis of the potential radiological dose to persons who would dive near the sunken ships and live on Bikini Island for a short period of time.« less

Estimates of the radiological dose to people living on Bikini Island for two weeks while diving in and around the sunken ships in Bikini Lagoon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robison, W.L.

1990-09-01

Bikini Island and Bikini Lagoon were contaminated by fallout from nuclear weapons tests conducted at the atoll by the United States from 1946 to 1958. The second test, Baker, of the Crossroads series was an underwater detonation in 1946 that sank several ships in the lagoon, including the USS Saratoga and the Japanese battleship Nagato. The ships received high-intensity gamma-ray and neutron bombardment from the Baker test, which induced radioactivity in the metal structures. Some of the tests conducted after the Baker shot (there were 21 tests in all) injected contaminated carbonate particles into the air, some of which weremore » deposited across the lagoon surface. Most of this contaminated soil then settled onto the ships' decks and other structures and on the lagoon bottom. These sunken ships provide an interesting location for divers. Recreational diving and swimming in and around the ships raises the question of the potential radiological dose from the radionuclides present in or on the ships and in the lagoon sediments. The purpose of this paper, therefore, is to present an analysis of the potential radiological dose to persons who would dive near the sunken ships and live on Bikini Island for a short period of time.« less

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

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.

Evaluation of lens distortion errors using an underwater camera system for video-based motion analysis

NASA Technical Reports Server (NTRS)

Poliner, Jeffrey; Fletcher, Lauren; Klute, Glenn K.

1994-01-01

Video-based motion analysis systems are widely employed to study human movement, using computers to capture, store, process, and analyze video data. This data can be collected in any environment where cameras can be located. One of the NASA facilities where human performance research is conducted is the Weightless Environment Training Facility (WETF), a pool of water which simulates zero-gravity with neutral buoyance. Underwater video collection in the WETF poses some unique problems. This project evaluates the error caused by the lens distortion of the WETF cameras. A grid of points of known dimensions was constructed and videotaped using a video vault underwater system. Recorded images were played back on a VCR and a personal computer grabbed and stored the images on disk. These images were then digitized to give calculated coordinates for the grid points. Errors were calculated as the distance from the known coordinates of the points to the calculated coordinates. It was demonstrated that errors from lens distortion could be as high as 8 percent. By avoiding the outermost regions of a wide-angle lens, the error can be kept smaller.

Composite Membrane with Underwater-Oleophobic Surface for Anti-Oil-Fouling Membrane Distillation.

PubMed

Wang, Zhangxin; Hou, Deyin; Lin, Shihong

2016-04-05

In this study, we fabricated a composite membrane for membrane distillation (MD) by modifying a commercial hydrophobic polyvinylidene fluoride (PVDF) membrane with a nanocomposite coating comprising silica nanoparticles, chitosan hydrogel and fluoro-polymer. The composite membrane exhibits asymmetric wettability, with the modified surface being in-air hydrophilic and underwater oleophobic, and the unmodified surface remaining hydrophobic. By comparing the performance of the composite membrane and the pristine PVDF membrane in direct contact MD experiments using a saline emulsion with 1000 ppm crude oil (in water), we showed that the fabricated composite membrane was significantly more resistant to oil fouling compared to the pristine hydrophobic PVDF membrane. Force spectroscopy was conducted for the interaction between an oil droplet and the membrane surface using a force tensiometer. The difference between the composite membrane and the pristine PVDF membrane in their interaction with an oil droplet served to explain the difference in the fouling propensities between these two membranes observed in MD experiments. The results from this study suggest that underwater oleophobic coating can effectively mitigate oil fouling in MD operations, and that the fabricated composite membrane with asymmetric wettability can enable MD to desalinate hypersaline wastewater with high concentrations of hydrophobic contaminants.

Optimization of decoupling performance of underwater acoustic coating with cavities via equivalent fluid model

NASA Astrophysics Data System (ADS)

Huang, Lingzhi; Xiao, Yong; Wen, Jihong; Zhang, Hao; Wen, Xisen

2018-07-01

Acoustic coatings with periodically arranged internal cavities have been successfully applied in submarines for the purpose of decoupling water from vibration of underwater structures, and thus reducing underwater sound radiation. Previous publications on decoupling acoustic coatings with cavities are mainly focused on the case of coatings with specific shaped cavities, including cylindrical and conical cavities. To explore better decoupling performance, an optimal design of acoustic coating with complex shaped cavities is attempted in this paper. An equivalent fluid model is proposed to characterize coatings with general axisymmetrical cavities. By employing the equivalent fluid model, an analytical vibroacoustic model is further developed for the prediction of sound radiation from an infinite plate covered with an equivalent fluid layer (as a replacement of original coating) and immersed in water. Numerical examples are provided to verify the equivalent fluid model. Based on a combining use of the analytical vibroacoustic model and a differential evolution algorithm, optimal designs for acoustic coatings with cavities are conducted. Numerical results demonstrate that the decoupling performance of acoustic coating can be significantly improved by employing special axisymmetrical cavities as compared to traditional cylindrical cavities.

Remote sensing of deep hermatypic coral reefs in Puerto Rico and the U.S. Virgin Islands using the Seabed autonomous underwater vehicle

NASA Astrophysics Data System (ADS)

Armstrong, Roy A.; Singh, Hanumant

2006-09-01

Optical imaging of coral reefs and other benthic communities present below one attenuation depth, the limit of effective airborne and satellite remote sensing, requires the use of in situ platforms such as autonomous underwater vehicles (AUVs). The Seabed AUV, which was designed for high-resolution underwater optical and acoustic imaging, was used to characterize several deep insular shelf reefs of Puerto Rico and the US Virgin Islands using digital imagery. The digital photo transects obtained by the Seabed AUV provided quantitative data on living coral, sponge, gorgonian, and macroalgal cover as well as coral species richness and diversity. Rugosity, an index of structural complexity, was derived from the pencil-beam acoustic data. The AUV benthic assessments could provide the required information for selecting unique areas of high coral cover, biodiversity and structural complexity for habitat protection and ecosystem-based management. Data from Seabed sensors and related imaging technologies are being used to conduct multi-beam sonar surveys, 3-D image reconstruction from a single camera, photo mosaicking, image based navigation, and multi-sensor fusion of acoustic and optical data.

NEEMO 21: Tools, Techniques, Technologies and Training for Science Exploration

NASA Technical Reports Server (NTRS)

Graff, T.; Young, K.; Coan, D.; Merselis, D.; Bellantuono, A.; Dougan, K.; Rodriguez-Lanetty, M.; Nedimyer, K.; Chappell, S.; Beaton, K.;

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.

Astronaut Robert L. Crippen prepares for underwater training session

NASA Technical Reports Server (NTRS)

1983-01-01

Astronaut Robert L. Crippen, STS-7 crew commander, adjusts his extravehicular mobility unit's (EMU) gloves prior to donning his helmet for a training session in the weightless environment test facility (WETF).

Analysis of NSWC Ocean EM Observatory Test Data

DTIC Science & Technology

2016-09-01

deployment locations. 1S. SUBJECT TERMS magnetic anomaly detection (MAD), oceanographic magnetic fields, coherence, magnetic noise reduction 16...analyses ......................................................................................... 11 3. Analysis of magnetic data...37 Appendix B: Feb 11 underwater magnetic data

Natural hydrocarbon seeps observation with underwater gliders and UV fluorescence sensor

NASA Astrophysics Data System (ADS)

Rochet, V.

2016-02-01

Hydrocarbons may leak to the near-surface from subsurface accumulations, from mature source rock, or by buoyancy along major cross-strata routes. The presence of migrating near-surface hydrocarbons can provide strong evidence for the presence of a working petroleum system, as well as valuable information on source, maturity, and migration pathways. Detection and characterization of hydrocarbons in the water column may then help to de-risk hydrocarbon plays at a very preliminary stage of an exploration program. In order to detect hydrocarbons in the water column, an underwater glider survey was conducted in an offshore frontier area. Driven by buoyancy variation, underwater gliders enable collecting data autonomously along the water column for weeks to months. Underwater gliders are regularly piloted from shore by satellite telemetry and do not require a surface supervising vessel resulting in substantial operational costs savings. The data compiled, over 700m depth of the water column, included temperature, salinity, pressure, dissolved oxygen and hydrocarbon components (phenanthrene and naphthalene) measured by "MINIFLUO" sensors to particularly target representative crude oil compounds Two gliders were deployed at sea, one from coast in shallow water and the other one offshore on the survey area. Both accurately squared the survey area following pre-defined lines and cross lines. Data files were transmitted by satellite telemetry in near real time during the performance of the mission for real time observations and appropriate re-positioning of the gliders. Using rechargeable underwater gliders increased reliability reducing the risk of leakage and associated logistics during operation at sea. Despite strong evidences of seabed seepages such as pockmarks, faults, etc, over the area of interest, no hydrocarbon indices were detected in the water column, which was confirmed later by seabed sample analysis. The use of glider platforms for hydrocarbon detection has been demonstrated, and they can nowadays be utilized as a proven and efficient technology for hydrocarbon exploration purposes beyond their classical oceanology uses.

Testing of a Composite Wavelet Filter to Enhance Automated Target Recognition in SONAR

NASA Technical Reports Server (NTRS)

Chiang, Jeffrey N.

2011-01-01

Automated Target Recognition (ATR) systems aim to automate target detection, recognition, and tracking. The current project applies a JPL ATR system to low resolution SONAR and camera videos taken from Unmanned Underwater Vehicles (UUVs). These SONAR images are inherently noisy and difficult to interpret, and pictures taken underwater are unreliable due to murkiness and inconsistent lighting. The ATR system breaks target recognition into three stages: 1) Videos of both SONAR and camera footage are broken into frames and preprocessed to enhance images and detect Regions of Interest (ROIs). 2) Features are extracted from these ROIs in preparation for classification. 3) ROIs are classified as true or false positives using a standard Neural Network based on the extracted features. Several preprocessing, feature extraction, and training methods are tested and discussed in this report.

Analysis of recordings from underwater controlled sources in the Pacific Ocean received by the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO)

NASA Astrophysics Data System (ADS)

Yamada, Tomoaki; Zampolli, Mario; Haralabus, Georgios; Heaney, Kevin; Prior, Mark; Isse, Takeshi

2016-04-01

Controlled impulsive scientific underwater sound sources in the Northwestern Pacific were observed at two IMS hydroacoustic stations in the Pacific Ocean. Although these experiments were conducted with the aim of studying the physical properties of the plate boundaries inside the Earth, they are also suitable for the investigation of long range underwater acoustic detections. In spite of the fact that the energy of these controlled impulsive scientific sources is significantly smaller than that of nuclear explosions, the signals were obtained by IMS hydrophone stations thousands of kilometres away and also by distant ocean bottom instruments operated by various Institutes, such as the Earthquake Research Institute, University of Tokyo. These experiments provide calibrated (yield, time, location) long-range acoustic transmissions, which enable one to examine the physics of long-range acoustic propagation and to verify the capabilities of the CTBTO IMS network to detect even small explosions.The two IMS stations used are H03 (Juan Fernandez Island, Chile) off the coast of Chile in the Southeastern Pacific and H11 (Wake Island, USA) in the Western Pacific. Both stations consist of two triplets of hydrophones in the SOFAR channel, which monitor the oceans for signs of nuclear explosions. H03 detected low-yield explosions above flat terrain at distances of 15,000 km across the Pacific as well as explosions above the landward slope off the coast of Japan at distances above 16,000 km across the Pacific. These records showed that source signatures, such as short duration and bubble pulses, were preserved over the long propagation distances. It was found that the observed maximum amplitudes from each source exhibit order of magnitude variations even when the yield and detonation depth are the same. The experimental data and transmission loss simulations suggest that bathymetric features around the sources and between the sources and the receivers are the main causes for these variations.

Use of an UROV to develop 3-D optical models of submarine environments

NASA Astrophysics Data System (ADS)

Null, W. D.; Landry, B. J.

2017-12-01

The ability to rapidly obtain high-fidelity bathymetry is crucial for a broad range of engineering, scientific, and defense applications ranging from bridge scour, bedform morphodynamics, and coral reef health to unexploded ordnance detection and monitoring. The present work introduces the use of an Underwater Remotely Operated Vehicle (UROV) to develop 3-D optical models of submarine environments. The UROV used a Raspberry Pi camera mounted to a small servo which allowed for pitch control. Prior to video data collection, in situ camera calibration was conducted with the system. Multiple image frames were extracted from the underwater video for 3D reconstruction using Structure from Motion (SFM). This system provides a simple and cost effective solution to obtaining detailed bathymetry in optically clear submarine environments.

Combined geophysical methods for mapping infiltration pathways at the Aurora Water Aquifer recharge and recovery site

NASA Astrophysics Data System (ADS)

Jasper, Cameron A.

Although aquifer recharge and recovery systems are a sustainable, decentralized, low cost, and low energy approach for the reclamation, treatment, and storage of post- treatment wastewater, they can suffer from poor infiltration rates and the development of a near-surface clogging layer within infiltration ponds. One such aquifer recharge and recovery system, the Aurora Water site in Colorado, U.S.A, functions at about 25% of its predicted capacity to recharge floodplain deposits by flooding infiltration ponds with post-treatment wastewater extracted from river bank aquifers along the South Platte River. The underwater self-potential method was developed to survey self-potential signals at the ground surface in a flooded infiltration pond for mapping infiltration pathways. A method for using heat as a groundwater tracer within the infiltration pond used an array of in situ high-resolution temperature sensing probes. Both relatively positive and negative underwater self-potential anomalies are consistent with observed recovery well pumping rates and specific discharge estimates from temperature data. Results from electrical resistivity tomography and electromagnetics surveys provide consistent electrical conductivity distributions associated with sediment textures. A lab method was developed for resistivity tests of near-surface sediment samples. Forward numerical modeling synthesizes the geophysical information to best match observed self- potential anomalies and provide permeability distributions, which is important for effective aquifer recharge and recovery system design, and optimization strategy development.

Tribological properties of fish scale inspired underwater superoleophobic hierarchical structure in aqueous environment

NASA Astrophysics Data System (ADS)

Lian, Zhongxu; Xu, Jinkai; Wan, Yanling; Li, Yiquan; Yu, Zhanjiang; Liu, Qimeng; Yu, Huadong

2017-10-01

Underwater superoleophobic surfaces are becoming increasingly important in regard to self-cleaning, anti-fouling, oil droplet transportation and water/oil separation. Although a great number of underwater superoleophobic surfaces have been demonstrated, their tribological properties remain impractical for the purposes of real-life applications. Herein, a two-step method of high speed wire electrical discharge machining and boiling water treatment was adopted to fabricate fish scale inspired underwater oil repellent hierarchical structure on an aluminum (Al) alloy 5083 surface. The hierarchical roughness and hydroxyl groups were obtained on the surface, and the surface exhibited the ability to prevent contact with organic fluids when submerged in water. Moreover, the tribological properties of underwater superoleophobic Al surfaces in aqueous environments were analyzed. The average friction coefficient of underwater superoleophobic surfaces was decreased compared with the polished Al surface. We believe that this research will contribute to the engineering application of underwater superoleophobic surfaces in the future.

46 CFR 169.229 - Drydock examination, internal structural examination, and underwater survey intervals.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., and underwater survey intervals. 169.229 Section 169.229 Shipping COAST GUARD, DEPARTMENT OF HOMELAND... Hauling Out § 169.229 Drydock examination, internal structural examination, and underwater survey... period unless it has been approved to undergo an underwater survey (UWILD) under § 169.230 of this part...

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.

Underwater magnetic gradiometer for magnetic anomaly detection, localization, and tracking

NASA Astrophysics Data System (ADS)

Kumar, S.; Sulzberger, G.; Bono, J.; Skvoretz, D.; Allen, G. I.; Clem, T. R.; Ebbert, M.; Bennett, S. L.; Ostrom, R. K.; Tzouris, A.

2007-04-01

GE Security and the Naval Surface Warfare Center, Panama City (NSWC-PC) have collaborated to develop a magnetic gradiometer, called the Real-time Tracking Gradiometer or RTG that is mounted inside an unmanned underwater vehicle (UUV). The RTG is part of a buried mine hunting platform being developed by the United States Navy. The RTG has been successfully used to make test runs on mine-like targets buried off the coast of Florida. We will present a general description of the system and latest results describing system performance. This system can be also potentially used for other applications including those in the area of Homeland Security.

[Cardiovascular effects of sodium chloride bath and underwater shower in coronary ischemia].

PubMed

Ghighineishvili, G R; Sirtori, P G; Balsamo, V; Miani, A; Di Francesco, A; Lanfranchi, M; Dagnoni, L; Mauro, F

Two hundred and eighteen patients (209 males and 9 females, mean age 57.1 +/- 0.6 years) with I class coronary ischemia were subdivided into two groups of 109 subjects each. Group I received NaCl baths, group II underwater massage-showers. On days 2-3 and 23-24 of treatment all underwent incremental stress testing until exhaustion. In group I, only subjects with moderate maximal muscular power improved their stress endurance. In group II, stress endurance significantly improved in all subjects: all hemodynamic indices (cardiac, output, stroke volume, systemic vascular resistances) showed variations indicative of improved cardiorespiratory function and peripheral blood supply.

Controlled trial of balneotherapy in treatment of low back pain.

PubMed Central

Konrad, K; Tatrai, T; Hunka, A; Vereckei, E; Korondi, I

1992-01-01

Three treatments for non-specific lumbar pain--balneotherapy, underwater traction bath, and underwater massage--were assessed in a randomised prospective controlled trial in 158 outpatients. Each group was treated for four weeks and patients were reviewed at the end of this period and at 12 months after entry to the trial. The prescription of analgesics and the pain score were significantly reduced in all three treated groups, but there was no difference between the three groups. No significant change occurred in spinal motion and the straight leg raising test. After one year only the analgesic consumption was significantly lower than in the control group. PMID:1535495

Station Keeping Results for Seabotix vLBV300 Underwater Vehicle near Newport, OR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hollinger, Geoffrey

This data set presents results testing the station keeping abilities of a tethered Seabotix vLBV300 underwater vehicle equipped with an inertial navigation system. These results are from an offshore deployment on April 20, 2016 off the coast of Newport, OR (44.678 degrees N, 124.109 degrees W). During the mission period, the sea state varied between 3 and 4, with an average significant wave height of 1.6 m. The vehicle utilizes an inertial navigation system based on a Gladiator Landmark 40 IMU coupled with a Teledyne Explorer Doppler Velocity Log to perform station keeping at a desired location and orientation.

The benefits of hydrotherapy to patients with spinal cord injuries.

PubMed

Ellapen, Terry J; Hammill, Henriëtte V; Swanepoel, Mariëtte; Strydom, Gert L

2018-01-01

Many patients with spinal cord injury (PWSCI) lead sedentary lifestyles, experiencing poor quality of life and medical challenges. PWSCI don't like to participate in land-based-exercises because it's tedious to perform the same exercises, decreasing their rehabilitative compliance and negatively impacting their well-being. An alternative exercise environment and exercises may alleviate boredom, enhancing compliance. Discuss the benefits of hydrotherapy to PWSCI concerning underwater gait-kinematics, thermoregulatory and cardiovascular responses and spasticity. A literature surveillance was conducted between 1998 and 2017, through the Crossref meta-database and Google Scholar, according to the PRISMA procedures. Key search words were water-therapy, aquatic-therapy, hydrotherapy, spinal cord injury, rehabilitation, human, kinematics, underwater gait, cardiorespiratory, thermoregulation and spasticity. The quality of each paper was evaluated using a modified Downs and Black Appraisal Scale. The participants were records pertaining to PWSCI and hydrotherapy. The outcomes of interest were: hydrotherapy interventions, the impact of hydrotherapy on gait-kinematics, thermoregulation during water submersion and cardiorespiratory function of PWSCI. Omitted records included: non-English publications from before 1998 or unrelated to hydrotherapy and PWSCI. The record screening admissibility was performed as follows: the title screen, the abstract screen and the full text screen. Literature search identified 1080 records. Upon application of the exclusion criteria, 92 titles, 29 abstracts and 17 full text records were eligible. Only 15 records were selected to be included in this clinical commentary. Evidence shows a paucity of randomised control trials (RCT) conducted in this field. Hydrotherapy improves PWSCI underwater gait-kinematics, cardiorespiratory and thermoregulatory responses and reduces spasticity.

The benefits of hydrotherapy to patients with spinal cord injuries

PubMed Central

Strydom, Gert L.

2018-01-01

Background Many patients with spinal cord injury (PWSCI) lead sedentary lifestyles, experiencing poor quality of life and medical challenges. PWSCI don’t like to participate in land-based-exercises because it’s tedious to perform the same exercises, decreasing their rehabilitative compliance and negatively impacting their well-being. An alternative exercise environment and exercises may alleviate boredom, enhancing compliance. Objectives Discuss the benefits of hydrotherapy to PWSCI concerning underwater gait-kinematics, thermoregulatory and cardiovascular responses and spasticity. Methodology A literature surveillance was conducted between 1998 and 2017, through the Crossref meta-database and Google Scholar, according to the PRISMA procedures. Key search words were water-therapy, aquatic-therapy, hydrotherapy, spinal cord injury, rehabilitation, human, kinematics, underwater gait, cardiorespiratory, thermoregulation and spasticity. The quality of each paper was evaluated using a modified Downs and Black Appraisal Scale. The participants were records pertaining to PWSCI and hydrotherapy. The outcomes of interest were: hydrotherapy interventions, the impact of hydrotherapy on gait-kinematics, thermoregulation during water submersion and cardiorespiratory function of PWSCI. Omitted records included: non-English publications from before 1998 or unrelated to hydrotherapy and PWSCI. The record screening admissibility was performed as follows: the title screen, the abstract screen and the full text screen. Results Literature search identified 1080 records. Upon application of the exclusion criteria, 92 titles, 29 abstracts and 17 full text records were eligible. Only 15 records were selected to be included in this clinical commentary. Evidence shows a paucity of randomised control trials (RCT) conducted in this field. Conclusion Hydrotherapy improves PWSCI underwater gait-kinematics, cardiorespiratory and thermoregulatory responses and reduces spasticity. PMID:29850439

Underwater fiber-wireless communication with a passive front end

NASA Astrophysics Data System (ADS)

Xu, Jing; Sun, Bin; Lyu, Weichao; Kong, Meiwei; Sarwar, Rohail; Han, Jun; Zhang, Wei; Deng, Ning

2017-11-01

We propose and experimentally demonstrate a novel concept on underwater fiber-wireless (Fi-Wi) communication system with a fully passive wireless front end. A low-cost step-index (SI) plastic optical fiber (POF) together with a passive collimating lens at the front end composes the underwater Fi-Wi architecture. We have achieved a 1.71-Gb/s transmission at a mean BER of 4.97 × 10-3 (1.30 × 10-3 when using power loading) over a 50-m SI-POF and 2-m underwater wireless channel using orthogonal frequency division multiplexing (OFDM). Although the wireless part is very short, it actually plays a crucial role in practical underwater implementation, especially in deep sea. Compared with the wired solution (e.g. using a 52-m POF cable without the UWOC part), the proposed underwater Fi-Wi scheme can save optical wet-mate connectors that are sophisticated, very expensive and difficult to install in deep ocean. By combining high-capacity robust POF with the mobility and ubiquity of underwater wireless optical communication (UWOC), the proposed underwater Fi-Wi technology will find wide application in ocean exploration.

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. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Biodeterioration of marble in an underwater environment.

PubMed

Cámara, Beatriz; de Buergo, Mónica Álvarez; Bethencourt, Manuel; Fernández-Montblanc, Tomás; La Russa, Mauro F; Ricca, Michela; Fort, Rafael

2017-12-31

This study examines the deterioration of geomaterials used throughout history that today may be found lying on the ocean floor. Submerged archaeological sites including cargoes from shipwrecks or ancient city ruins have been a topic of interest from a perspective of in situ musealization, as a way of making underwater cultural heritage accessible to the public. In an experimental study conducted at an underwater archaeological site in the Bay of Cádiz (SW Spain), we subjected two types of marble (Carrara and Macael) to three conditions to which submerged archaeological objects are often exposed: full exposure to the water column, natural processes of burial and unearthing, or permanent burial. After an 18-month study period, the factor found to mostly affect these materials was their biological colonization. This factor was assessed by estimating total surface biocover and the rate of surface biocolonization, and also through the identification of skeletons and associated alteration forms by light microscopy, and scanning electron microscopy (SEM). Biofouling and bioerosion were the main causes of biodeterioration and dependent on the position of the marble specimens in the seawater. The response of both materials was similar, though dolomite crystals in the Carrara marble acted as a protective barrier against actively penetrating microorganisms. These investigations have allowed the study of tracers left by epilithic encrusting organisms and endolithic bioeroders on marbles intentionally exposed to seawater, providing new insights to the understanding of the biodeterioration processes occurring in cultural heritage stones, with significant implications when they are part of underwater archaeological remains. Copyright © 2017 Elsevier B.V. All rights reserved.

Stratigraphic Evidence for Environmental Change in a Bermudian Coastal Underwater Cave (Palm Cave System) in Response to Holocene Sea-level Rise

NASA Astrophysics Data System (ADS)

Cresswell, J. N.; van Hengstum, P. J.; Iliffe, T. M.

2016-12-01

Unique environments exist worldwide in coastal underwater caves, including those from Bermuda, which has been a global epicenter for interdisciplinary cave research. However, the development of environments, ecosystems, and sedimentary deposits in coastal underwater caves, particularly over millennial timescales is poorly understood, with previous research from Bermuda indicating a critical role for sea-level rise in driving environmental change. A multi-proxy stratigraphic analysis of 14 sediment cores that were collected from the Palm Cave System in Bermuda from 2 m to 20 m water depths was conducted to better understand Holocene-scale environmental change in coastal underwater caves (e.g., textural analysis, x-radiographs, microfossil analysis, radiocarbon dating). The rate of deposition was found to be variable throughout time and dependent upon the proximity of core locations to cave openings (`karst windows') and conduit geometry. The oldest recovered sediment was likely Pleistocene-aged, terra-rosa soil deposits that predate the Holocene inundation. By 9500 Cal yrs BP, deposition was dominated by organic-rich facies (gyttja), with agglutinated brackish foraminifera (Trochammina, Polysaccammina) and bivalves indicating brackish aquatic conditions in the system by 9200 Cal yrs BP. A system-wide shift to carbonate deposition occurred 8500 Cal yrs BP, which indicates the onset of oxygenated marine water entering the cave and development of a marine-dominated (i.e., submarine) cave environment. Comparison with local maximum sea-level indicators shows that inundation of the Bermuda platform by Holocene sea-level rise likely drove environmental change in the Palm Cave System.

46 CFR 115.640 - Pre-Survey meeting.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Pre-Survey meeting. 115.640 Section 115.640 Shipping... Tailshaft Examinations § 115.640 Pre-Survey meeting. (a) You must conduct a pre-survey meeting to discuss... of the ROV operating company must attend the pre-survey meeting and address the underwater ROV's...

46 CFR 115.640 - Pre-Survey meeting.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Pre-Survey meeting. 115.640 Section 115.640 Shipping... Tailshaft Examinations § 115.640 Pre-Survey meeting. (a) You must conduct a pre-survey meeting to discuss... of the ROV operating company must attend the pre-survey meeting and address the underwater ROV's...

46 CFR 115.640 - Pre-Survey meeting.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Pre-Survey meeting. 115.640 Section 115.640 Shipping... Tailshaft Examinations § 115.640 Pre-Survey meeting. (a) You must conduct a pre-survey meeting to discuss... of the ROV operating company must attend the pre-survey meeting and address the underwater ROV's...

46 CFR 115.640 - Pre-Survey meeting.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Pre-Survey meeting. 115.640 Section 115.640 Shipping... Tailshaft Examinations § 115.640 Pre-Survey meeting. (a) You must conduct a pre-survey meeting to discuss... of the ROV operating company must attend the pre-survey meeting and address the underwater ROV's...

46 CFR 115.640 - Pre-Survey meeting.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Pre-Survey meeting. 115.640 Section 115.640 Shipping... Tailshaft Examinations § 115.640 Pre-Survey meeting. (a) You must conduct a pre-survey meeting to discuss... of the ROV operating company must attend the pre-survey meeting and address the underwater ROV's...

Demonstration of ROV-based Underwater Electromagnetic Array Technology

DTIC Science & Technology

2017-05-25

Volume Magnetic Source Model that Was Modified to Address EM Propagation through a Conductive Seawater Medium...16  Figure 7. Still Shots of the Integrated ROV- EM System (left) and the EM Sensor (right) Performing Bottom Following...of Defense DVL Doppler Velocity Log E Easting EOD Explosive Ordnance Disposal EM Electromagnetic EMI Electromagnetic Induction EMF

Underwater Advanced Time-Domain Electromagnetic System

DTIC Science & Technology

2017-03-03

SUPPLEMENTARY NOTES 14. ABSTRACT The overall objective of the project is to design , build and demonstrate an underwater advanced time -domain...Description The overall objective of the project is to design , build and demonstrate an underwater advanced time - domain electromagnetic (TEM) system...Electromagnetic System Design (July, 2015), and in the Underwater Advanced Time -Domain Electromagnetic System Evaluation Plan (October, 2016). A

A High-Resolution Cluster of Oceanographic Instruments for Boundary Layer Measurements under Ice.

DTIC Science & Technology

1985-11-01

arrangement for use with laser velocimetry. The EO components are mounted on an aluminum chassis, which is in turn placed in an underwater housing made...temperature/conductivity probe pair used * on the HRC cluster. It consists of a thermistor probe (FASTIP, Model FP07, Thermometrics , Inc.) and a dual...component. The orientation of all three DLT)V pairs is shown in Figure 1. 3.2 Temperature and Conductivity Probes The FASTIP thermistor by Thermometrics

Computational Modeling and Experimental Validation of Shock Induced Damage in Woven E-Glass/Vinylester Laminates

NASA Astrophysics Data System (ADS)

Hufner, D. R.; Augustine, M. R.

2018-05-01

A novel experimental method was developed to simulate underwater explosion pressure pulses within a laboratory environment. An impact-based experimental apparatus was constructed; capable of generating pressure pulses with basic character similar to underwater explosions, while also allowing the pulse to be tuned to different intensities. Having the capability to vary the shock impulse was considered essential to producing various levels of shock-induced damage without the need to modify the fixture. The experimental apparatus and test method are considered ideal for investigating the shock response of composite material systems and/or experimental validation of new material models. One such test program is presented herein, in which a series of E-glass/Vinylester laminates were subjected to a range of shock pulses that induced varying degrees of damage. Analysis-test correlations were performed using a rate-dependent constitutive model capable of representing anisotropic damage and ultimate yarn failure. Agreement between analytical predictions and experimental results was considered acceptable.

Zero-power autonomous buoyancy system controlled by microbial gas production

NASA Astrophysics Data System (ADS)

Wu, Peter K.; Fitzgerald, Lisa A.; Biffinger, Justin C.; Spargo, Barry J.; Houston, Brian H.; Bucaro, Joseph A.; Ringeisen, Bradley R.

2011-05-01

A zero-power ballast control system that could be used to float and submerge a device solely using a gas source was built and tested. This system could be used to convey sensors, data loggers, and communication devices necessary for water quality monitoring and other applications by periodically maneuvering up and down a water column. Operational parameters for the system such as duration of the submerged and buoyant states can be varied according to its design. The gas source can be of any origin, e.g., compressed air, underwater gas vent, gas produced by microbes, etc. The zero-power ballast system was initially tested using a gas pump and further tested using gas produced by Clostridium acetobutylicum. Using microbial gas production as the only source of gas and no electrical power during operation, the system successfully floated and submerged periodically with a period of 30 min for at least 24 h. Together with microbial fuel cells, this system opens up possibilities for underwater monitoring systems that could function indefinitely.

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

Design and validation of an automated hydrostatic weighing system.

PubMed

McClenaghan, B A; Rocchio, L

1986-08-01

The purpose of this study was to design and evaluate the validity of an automated technique to assess body density using a computerized hydrostatic weighing system. An existing hydrostatic tank was modified and interfaced with a microcomputer equipped with an analog-to-digital converter. Software was designed to input variables, control the collection of data, calculate selected measurements, and provide a summary of the results of each session. Validity of the data obtained utilizing the automated hydrostatic weighing system was estimated by: evaluating the reliability of the transducer/computer interface to measure objects of known underwater weight; comparing the data against a criterion measure; and determining inter-session subject reliability. Values obtained from the automated system were found to be highly correlated with known underwater weights (r = 0.99, SEE = 0.0060 kg). Data concurrently obtained utilizing the automated system and a manual chart recorder were also found to be highly correlated (r = 0.99, SEE = 0.0606 kg). Inter-session subject reliability was determined utilizing data collected on subjects (N = 16) tested on two occasions approximately 24 h apart. Correlations revealed high relationships between measures of underwater weight (r = 0.99, SEE = 0.1399 kg) and body density (r = 0.98, SEE = 0.00244 g X cm-1). Results indicate that a computerized hydrostatic weighing system is a valid and reliable method for determining underwater weight.

Terminal Homing for Autonomous Underwater Vehicle Docking

DTIC Science & Technology

2016-06-01

underwater domain, accurate navigation. Above the water, light and electromagnetic signals travel well through air and space, mediums that allow for a...DISTRIBUTION CODE 13. ABSTRACT The use of docking stations for autonomous underwater vehicles (AUV) provides the ability to keep a vehicle on...Mechanical and Aerospace Engineering iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT The use of docking stations for autonomous underwater

Underwater Acoustic Beacon Location System

DTIC Science & Technology

2016-12-23

300087 1 of 31 UNDERWATER ACOUSTIC BEACON LOCATION SYSTEM [0001] The present application claims the benefit of United States Provisional...Application Serial Number 62/297,179 filed on February 19, 2016 by the inventor, Steven E. Crocker and entitled “ Underwater Acoustic Beacon...search for and can locate an underwater location beacon. Attorney Docket No. 300087 2 of 31 (2) Description of the Prior Art [0005

Autonomous Adaptive Acoustic Relay Positioning

DTIC Science & Technology

2013-09-01

underwater acoustic sensor networks . In Proc. 1st ACM International Work- shop on Underwater Networks , pages 7–16, 2006. [4] A Alvarez, A...routing in underwater delay/disruption tolerant sensor networks . In Wireless on Demand Network Systems and Services, 2008. WONS 2008. Fifth Annual...the development of multi-vehicle applications in the ocean, and the main mode of wireless data transmission underwater is acoustic .

Non-Data Aided Doppler Shift Estimation for Underwater Acoustic Communication

DTIC Science & Technology

2014-05-01

in underwater acoustic wireless sensor networks . We analyzed the data collected from our experiments using non-data aided (blind) techniques such as...investigated different methods for blind Doppler shift estimation and compensation for a single carrier in underwater acoustic wireless sensor ...distributed underwater sensor networks . Detailed experimental and simulated results based on second order cyclostationary features of the received signals

Global Network Connectivity Assessment via Local Data Exchange for Underwater Acoustic Sensor Networks

DTIC Science & Technology

2014-03-31

Network Connectivity Assessment via Local Data Exchange for Underwater Acoustic Sensor Networks M.M. Asadi H. Mahboubi A...2014 Global Network Connectivity Assessment via Local Data Exchange for Underwater Acoustic Sensor Networks Contract Report # AMBUSH.1.1 Contract...pi j /= 0. The sensor network considered in this work is composed of underwater sensors , which use acoustic waves for

Underwater 3D Surface Measurement Using Fringe Projection Based Scanning Devices

PubMed Central

Bräuer-Burchardt, Christian; Heinze, Matthias; Schmidt, Ingo; Kühmstedt, Peter; Notni, Gunther

2015-01-01

In this work we show the principle of optical 3D surface measurements based on the fringe projection technique for underwater applications. The challenges of underwater use of this technique are shown and discussed in comparison with the classical application. We describe an extended camera model which takes refraction effects into account as well as a proposal of an effective, low-effort calibration procedure for underwater optical stereo scanners. This calibration technique combines a classical air calibration based on the pinhole model with ray-based modeling and requires only a few underwater recordings of an object of known length and a planar surface. We demonstrate a new underwater 3D scanning device based on the fringe projection technique. It has a weight of about 10 kg and the maximal water depth for application of the scanner is 40 m. It covers an underwater measurement volume of 250 mm × 200 mm × 120 mm. The surface of the measurement objects is captured with a lateral resolution of 150 μm in a third of a second. Calibration evaluation results are presented and examples of first underwater measurements are given. PMID:26703624

Blue-light digital communication in underwater environments utilizing orbital angular momentum

NASA Astrophysics Data System (ADS)

Baghdady, Joshua; Miller, Keith; Osler, Sean; Morgan, Kaitlyn; Li, Wenzhe; Johnson, Eric; Cochenour, Brandon

2016-05-01

Underwater optical communication has recently become the topic of much investigation as the demands for underwater data transmission have rapidly grown in recent years. The need for reliable, high-speed, secure underwater communication has turned increasingly to blue-light optical solutions. The blue-green visible wavelength window provides an attractive solution to the problem of underwater data transmission thanks to its low attenuation, where traditional RF solutions used in free-space communications collapse. Beginning with GaN laser diodes as the optical source, this work explores the encoding and transmission of digital data across underwater environments of varying turbidities. Given the challenges present in an underwater environment, such as the mechanical and optical turbulences that make proper alignment difficult to maintain, it is desirable to achieve extremely high data rates in order to allow the time window of alignment between the transmitter and receiver to be as small as possible. In this paper, work is done to increase underwater data rates through the use of orbital angular momentum. Results are shown for a range of data rates across a variety of channel types ranging in turbidity from that of a clear ocean to a dirty harbor.

Fitting primitive shapes in point clouds: a practical approach to improve autonomous underwater grasp specification of unknown objects

NASA Astrophysics Data System (ADS)

Fornas, D.; Sales, J.; Peñalver, A.; Pérez, J.; Fernández, J. J.; Marín, R.; Sanz, P. J.

2016-03-01

This article presents research on the subject of autonomous underwater robot manipulation. Ongoing research in underwater robotics intends to increase the autonomy of intervention operations that require physical interaction in order to achieve social benefits in fields such as archaeology or biology that cannot afford the expenses of costly underwater operations using remote operated vehicles. Autonomous grasping is still a very challenging skill, especially in underwater environments, with highly unstructured scenarios, limited availability of sensors and adverse conditions that affect the robot perception and control systems. To tackle these issues, we propose the use of vision and segmentation techniques that aim to improve the specification of grasping operations on underwater primitive shaped objects. Several sources of stereo information are used to gather 3D information in order to obtain a model of the object. Using a RANSAC segmentation algorithm, the model parameters are estimated and a set of feasible grasps are computed. This approach is validated in both simulated and real underwater scenarios.

Quantum imaging for underwater arctic navigation

NASA Astrophysics Data System (ADS)

Lanzagorta, Marco

2017-05-01

The precise navigation of underwater vehicles is a difficult task due to the challenges imposed by the variable oceanic environment. It is particularly difficult if the underwater vehicle is trying to navigate under the Arctic ice shelf. Indeed, in this scenario traditional navigation devices such as GPS, compasses and gyrocompasses are unavailable or unreliable. In addition, the shape and thickness of the ice shelf is variable throughout the year. Current Arctic underwater navigation systems include sonar arrays to detect the proximity to the ice. However, these systems are undesirable in a wartime environment, as the sound gives away the position of the underwater vehicle. In this paper we briefly describe the theoretical design of a quantum imaging system that could allow the safe and stealthy navigation of underwater Arctic vehicles.

Safety and Suitability for Service Assessment Testing for Surface and Underwater Launched Munitions

DTIC Science & Technology

2014-12-05

test efficiency that tend to associate the Analytical S3 Test Approach with large, complex munition systems and the Empirical S3 Test Approach with...the smaller, less complex munition systems . 8.1 ANALYTICAL S3 TEST APPROACH. The Analytical S3 test approach, as shown in Figure 3, evaluates...assets than the Analytical S3 Test approach to establish the safety margin of the system . This approach is generally applicable to small munitions

NPF MECHANICAL CELL NaK DISPOSAL AND FUME ABATEMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rey, G.

Some of the fuels originally scheduled for processing in the nonproduction fuel (NPF) processing program incorporated sodium or sodium- potassium alloy (NaK) as the bonding material between stainless-steel cladding and the uranium or uranium-molybdenum alloy core. Because of the special hazards involved in handling NaK, studies were made to determine safe methods for processing NaK-containing fuels. An underwater NaK dispensing system was installed, and tests were made to determine the characteristics of the NaK-water reaction. The equipment consisted of a dispenser, reaction pan, and off-gas scrubber. After initinl studies, a prototype test was made wherein U-Mo canned slugs containing NaKmore » reservoirs were hack sawed underwater. The studies demonstrated that the NaK reservoirs can be safely deactivated by hack sawing under a submerged hood in a shallow water bath. (W.L.H.)« less

Based on the rainfall system platform raindrops research and analysis of pressure loss

NASA Astrophysics Data System (ADS)

Cao, Gang; Sun, Jian

2018-01-01

With the rapid development of China’s military career, land, sea and air force all services and equipment of modern equipment need to be in the rain test, and verify its might suffer during transportation, storage or use a different environment temperature lower water or use underwater, the water is derived from the heavy rain, the wind and rain, sprinkler system, splash water, water wheel, a violent shock waves or use underwater, etcTest the product performance and quality, under the condition of rainfall system platform in the process of development, how to control the raindrops pressure loss becomes the key to whether the system can simulate the real rainfall [1], this paper is according to the rainfall intensity, nozzle flow resistance, meet water flow of rain pressure loss calculation and analysis, and system arrangement of the optimal solution of rainfall is obtained [2].

Analysis of security and threat of underwater wireless sensor network topology

NASA Astrophysics Data System (ADS)

Yang, Guang; Wei, Zhiqiang; Cong, Yanping; Jia, Dongning

2012-04-01

Underwater wireless sensor networks (UWSNs) are a subclass of wireless sensor networks. Underwater sensor deployment is a significant challenge due to the characteristics of UWSNs and underwater environment. Recent researches for UWSNs deployment mostly focus on the maintenance of network connectivity and maximum communication coverage. However, the broadcast nature of the transmission medium incurs various types of security attacks. This paper studies the security issues and threats of UWSNs topology. Based on the cluster-based topology, an underwater cluster-based security scheme (U-CBSS) is presented to defend against these attacks. and safety.

Mapping Underwater Sound in the Dutch Part of the North Sea.

PubMed

Sertlek, H Özkan; Aarts, Geert; Brasseur, Sophie; Slabbekoorn, Hans; ten Cate, Carel; von Benda-Beckmann, Alexander M; Ainslie, Michael A

2016-01-01

The European Union requires member states to achieve or maintain good environmental status for their marine territorial waters and explicitly mentions potentially adverse effects of underwater sound. In this study, we focused on producing maps of underwater sound from various natural and anthropogenic origins in the Dutch North Sea. The source properties and sound propagation are simulated by mathematical methods. These maps could be used to assess and predict large-scale effects on behavior and distribution of underwater marine life and therefore become a valuable tool in assessing and managing the impact of underwater sound on marine life.

Development of fast wireless detection system for fixed offshore platform

NASA Astrophysics Data System (ADS)

Li, Zhigang; Yu, Yan; Jiao, Dong; Wang, Jie; Li, Zhirui; Ou, Jinping

2011-04-01

Offshore platforms' security is concerned since in 1950s and 1960s, and in the early 1980s some important specifications and standards are built, and all these provide technical basis of fixed platform design, construction, installation and evaluation. With the condition that more and more platforms are in serving over age, the research about the evaluation and detection technology of offshore platform has been a hotspot, especially underwater detection, and assessment method based on the finite element calculation. For fixed platform structure detection, conventional NDT methods, such as eddy current, magnetic powder, permeate, X-ray and ultrasonic, etc, are generally used. These techniques are more mature, intuitive, but underwater detection needs underwater robot, the necessary supporting tools of auxiliary equipment, and trained professional team, thus resources and cost used are considerable, installation time of test equipment is long. This project presents a new kind of fast wireless detection and damage diagnosis system for fixed offshore platform using wireless sensor networks, that is, wireless sensor nodes can be put quickly on the offshore platform, detect offshore platform structure global status by wireless communication, and then make diagnosis. This system is operated simply, suitable for offshore platform integrity states rapid assessment. The designed system consists in intelligence acquisition equipment and 8 wireless collection nodes, the whole system has 64 collection channels, namely every wireless collection node has eight 16-bit accuracy of A/D channels. Wireless collection node, integrated with vibration sensing unit, embedded low-power micro-processing unit, wireless transceiver unit, large-capacity power unit, and GPS time synchronization unit, can finish the functions such as vibration data collection, initial analysis, data storage, data wireless transmission. Intelligence acquisition equipment, integrated with high-performance computation unit, wireless transceiver unit, mobile power unit and embedded data analysis software, can totally control multi-wireless collection nodes, receive and analyze data, parameter identification. Data is transmitted at the 2.4GHz wireless communication channel, every sensing data channel in charge of data transmission is in a stable frequency band, control channel responsible for the control of power parameters is in a public frequency band. The test is initially conducted for the designed system, experimental results show that the system has good application prospects and practical value with fast arrangement, high sampling rate, high resolution, capacity of low frequency detection.

Accuracy Assessment of GO Pro Hero 3 (black) Camera in Underwater Environment

NASA Astrophysics Data System (ADS)

Helmholz, , P.; Long, J.; Munsie, T.; Belton, D.

2016-06-01

Modern digital cameras are increasing in quality whilst decreasing in size. In the last decade, a number of waterproof consumer digital cameras (action cameras) have become available, which often cost less than 500. A possible application of such action cameras is in the field of Underwater Photogrammetry. Especially with respect to the fact that with the change of the medium to below water can in turn counteract the distortions present. The goal of this paper is to investigate the suitability of such action cameras for underwater photogrammetric applications focusing on the stability of the camera and the accuracy of the derived coordinates for possible photogrammetric applications. For this paper a series of image sequences was capture in a water tank. A calibration frame was placed in the water tank allowing the calibration of the camera and the validation of the measurements using check points. The accuracy assessment covered three test sets operating three GoPro sports cameras of the same model (Hero 3 black). The test set included the handling of the camera in a controlled manner where the camera was only dunked into the water tank using 7MP and 12MP resolution and a rough handling where the camera was shaken as well as being removed from the waterproof case using 12MP resolution. The tests showed that the camera stability was given with a maximum standard deviation of the camera constant σc of 0.0031mm for 7MB (for an average c of 2.720mm) and 0.0072 mm for 12MB (for an average c of 3.642mm). The residual test of the check points gave for the 7MB test series the largest rms value with only 0.450mm and the largest maximal residual of only 2.5 mm. For the 12MB test series the maximum rms value is 0. 653mm.

The Need for US Coast Guard Underwater Mission Development

DTIC Science & Technology

2013-04-23

vehicles and proliferation of fiber optic cables, raising the level of human interactions in the underwater environment. Besides the benefits from the...unmanned underwater vehicles, proliferation of fiber optic cables, and observation posts on the ocean floor will raise the level of human interactions...world’s demand for wood grows.39 As technology progresses, undersea infrastructure will continue to expand. Already, underwater fiber optic communication

Joint Optimal Placement and Energy Allocation of Underwater Sensors in a Tree Topology

DTIC Science & Technology

2014-03-10

underwater acoustic sensor nodes with respect to the capacity of the wireless links between the... underwater acoustic sensor nodes with respect to the capacity of the wireless links between the nodes. We assumed that the energy consumption of...nodes’ optimal placements. We achieve the optimal placement of the underwater acoustic sensor nodes with respect to the capacity of the wireless

Optimal Scheduling for Underwater Communications in Multiple-User Scenarios

DTIC Science & Technology

2015-09-30

term goals of this project is to analyze and propose energy-efficient communication techniques for underwater acoustic sensor networks . These...investigate the possibility that these underwater acoustic networks disrupt the behavior of surrounding species of marine mammals. As a consequence of... underwater VHF acoustics , high data rate/short range acoustic communications and networking , and acoustic sensing in the VHF regime. WORK COMPLETED We

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Pengfei; Roy, Subrata, E-mail: roy@ufl.edu

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 watermore » 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.« less

Assessment of Enterococcus Levels in Recreational Beach Sand Along the Rhode Island Coast.

PubMed

Coakley, Eugenie; Parris, Amie L; Wyman, Al; Latowsky, Gretchen

2016-04-01

Recent studies have shown that coastal beach sand as well as coastal ocean water can be contaminated with fecal indicator Enterococcus bacteria (ENT). A study of sand ENT concentrations over a four-week period at 12 Rhode Island beaches was conducted during the summer of 2009. While average contamination was low relative to water quality standards, every beach had at least one day with very high sand ENT readings. On 10 of the 12 beaches, a statistically significant gradient occurred in geometric mean ENT concentrations among tidal zones, with dry (supratidal, or above high tide mark) sand having the highest level, followed by wet (intratidal, or below high tide mark) and underwater sand. Beaches with higher wave action had significantly lower ENT levels in wet and underwater sand compared to beaches with lower wave action.

OPTICAL correlation identification technology applied in underwater laser imaging target identification

NASA Astrophysics Data System (ADS)

Yao, Guang-tao; Zhang, Xiao-hui; Ge, Wei-long

2012-01-01

The underwater laser imaging detection is an effective method of detecting short distance target underwater as an important complement of sonar detection. With the development of underwater laser imaging technology and underwater vehicle technology, the underwater automatic target identification has gotten more and more attention, and is a research difficulty in the area of underwater optical imaging information processing. Today, underwater automatic target identification based on optical imaging is usually realized with the method of digital circuit software programming. The algorithm realization and control of this method is very flexible. However, the optical imaging information is 2D image even 3D image, the amount of imaging processing information is abundant, so the electronic hardware with pure digital algorithm will need long identification time and is hard to meet the demands of real-time identification. If adopt computer parallel processing, the identification speed can be improved, but it will increase complexity, size and power consumption. This paper attempts to apply optical correlation identification technology to realize underwater automatic target identification. The optics correlation identification technology utilizes the Fourier transform characteristic of Fourier lens which can accomplish Fourier transform of image information in the level of nanosecond, and optical space interconnection calculation has the features of parallel, high speed, large capacity and high resolution, combines the flexibility of calculation and control of digital circuit method to realize optoelectronic hybrid identification mode. We reduce theoretical formulation of correlation identification and analyze the principle of optical correlation identification, and write MATLAB simulation program. We adopt single frame image obtained in underwater range gating laser imaging to identify, and through identifying and locating the different positions of target, we can improve the speed and orientation efficiency of target identification effectively, and validate the feasibility of this method primarily.

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.

A man-made object detection for underwater TV

NASA Astrophysics Data System (ADS)

Cheng, Binbin; Wang, Wenwu; Chen, Yao

2018-03-01

It is a great challenging task to complete an automatic search of objects underwater. Usually the forward looking sonar is used to find the target, and then the initial identification of the target is completed by the side-scan sonar, and finally the confirmation of the target is accomplished by underwater TV. This paper presents an efficient method for automatic extraction of man-made sensitive targets in underwater TV. Firstly, the image of underwater TV is simplified with taking full advantage of the prior knowledge of the target and the background; then template matching technology is used for target detection; finally the target is confirmed by extracting parallel lines on the target contour. The algorithm is formulated for real-time execution on limited-memory commercial-of-the-shelf platforms and is capable of detection objects in underwater TV.

Evaluating the SCC resistance of underwater welds in sodium tetrathionate

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, R.A.; Angeliu, T.M.

1997-12-01

The susceptibility of welds to stress corrosion cracking (SCC) is enhanced by the surface residual tensile stresses generated by the typical welding process. However, underwater plasma transferred arc (PTA) welding has been shown to produce compressive surface residual stresses, an encouraging result if repairs of cracked boiling water reactor (BWR) components are to be made without further endangering them to SCC. This program was designed to verify that underwater PTA welds are resistant to SCC and to determine if underwater PTA welding could mitigate SCC in potentially susceptible welds. This was achieved by exposing various welds on solution annealed (SA)more » and SA + thermally sensitized 304 stainless steel at 25 C in a solution of 1.5 gm/liter of sodium sulfide added to 0.05M sodium tetrathionate, titrated to a pH of 1.25 with H{sub 2}SO{sub 4}. The autogeneous welds were produced using gas tungsten arc (GTA) and plasma transferred arc (PTA) welding under atmospheric conditions, and PTA welding underwater. After 1 hour of sodium tetrathionate exposure, GTA and air PTA welds exhibited SCC while the underwater PTA weld heat affected zones were more resistant. Underwater PTA welds bisecting a GTA weld eliminated the cracking in the GTA weld heat affected zone under certain conditions. The lack of IG cracking in the region influenced by the underwater PTA weld is consistent with the measurement of compressive surface residual stresses inherent to the underwater welding process.« less

CSI feedback-based CS for underwater acoustic adaptive modulation OFDM system with channel prediction

NASA Astrophysics Data System (ADS)

Kuai, Xiao-yan; Sun, Hai-xin; Qi, Jie; Cheng, En; Xu, Xiao-ka; Guo, Yu-hui; Chen, You-gan

2014-06-01

In this paper, we investigate the performance of adaptive modulation (AM) orthogonal frequency division multiplexing (OFDM) system in underwater acoustic (UWA) communications. The aim is to solve the problem of large feedback overhead for channel state information (CSI) in every subcarrier. A novel CSI feedback scheme is proposed based on the theory of compressed sensing (CS). We propose a feedback from the receiver that only feedback the sparse channel parameters. Additionally, prediction of the channel state is proposed every several symbols to realize the AM in practice. We describe a linear channel prediction algorithm which is used in adaptive transmission. This system has been tested in the real underwater acoustic channel. The linear channel prediction makes the AM transmission techniques more feasible for acoustic channel communications. The simulation and experiment show that significant improvements can be obtained both in bit error rate (BER) and throughput in the AM scheme compared with the fixed Quadrature Phase Shift Keying (QPSK) modulation scheme. Moreover, the performance with standard CS outperforms the Discrete Cosine Transform (DCT) method.

Instruments and Methodologies for the Underwater Tridimensional Digitization and Data Musealization

NASA Astrophysics Data System (ADS)

Repola, L.; Memmolo, R.; Signoretti, D.

2015-04-01

In the research started within the SINAPSIS project of the Università degli Studi Suor Orsola Benincasa an underwater stereoscopic scanning aimed at surveying of submerged archaeological sites, integrable to standard systems for geomorphological detection of the coast, has been developed. The project involves the construction of hardware consisting of an aluminum frame supporting a pair of GoPro Hero Black Edition cameras and software for the production of point clouds and the initial processing of data. The software has features for stereoscopic vision system calibration, reduction of noise and the of distortion of underwater captured images, searching for corresponding points of stereoscopic images using stereo-matching algorithms (dense and sparse), for points cloud generating and filtering. Only after various calibration and survey tests carried out during the excavations envisaged in the project, the mastery of methods for an efficient acquisition of data has been achieved. The current development of the system has allowed generation of portions of digital models of real submerged scenes. A semi-automatic procedure for global registration of partial models is under development as a useful aid for the study and musealization of sites.

Underwater audiogram of a false killer whale (Pseudorca crassidens).

PubMed

Thomas, J; Chun, N; Au, W; Pugh, K

1988-09-01

Underwater audiograms are available for only a few odontocete species. A false killer whale (Pseudorca crassidens) was trained at Sea Life Park in Oahu, Hawaii for an underwater hearing test using a go/no-go response paradigm. Over a 6-month period, auditory thresholds from 2-115 kHz were measured using an up/down staircase psychometric technique. The resulting audiogram showed hearing sensitivities below 64 kHz similar to those of belugas (Delphinapterus leucas) and Atlantic bottlenosed dolphins (Tursiops truncatus). Above 64 kHz, this Pseudorca had a rapid decrease in sensitivity of about 150 dB per octave. A similar decrease in sensitivity occurs at 32 kHz in the killer whale, at 50 kHz in the Amazon River dolphin, at 120 kHz in the beluga, at 140 kHz in the bottlenosed dolphin, and at 140 kHz in the harbor porpoise. The most sensitive range of hearing was from 16-64 kHz (a range of 10 dB from the maximum sensitivity). This range corresponds with the peak frequency of echolocation pulses recorded from captive Pseudorca.

A high-frequency warm shallow water acoustic communications channel model and measurements.

PubMed

Chitre, Mandar

2007-11-01

Underwater acoustic communication is a core enabling technology with applications in ocean monitoring using remote sensors and autonomous underwater vehicles. One of the more challenging underwater acoustic communication channels is the medium-range very shallow warm-water channel, common in tropical coastal regions. This channel exhibits two key features-extensive time-varying multipath and high levels of non-Gaussian ambient noise due to snapping shrimp-both of which limit the performance of traditional communication techniques. A good understanding of the communications channel is key to the design of communication systems. It aids in the development of signal processing techniques as well as in the testing of the techniques via simulation. In this article, a physics-based channel model for the very shallow warm-water acoustic channel at high frequencies is developed, which are of interest to medium-range communication system developers. The model is based on ray acoustics and includes time-varying statistical effects as well as non-Gaussian ambient noise statistics observed during channel studies. The model is calibrated and its accuracy validated using measurements made at sea.

Performance of multimirror quartzline lamps in a high-pressure, underwater environment

NASA Technical Reports Server (NTRS)

Slater, Howard A.

1988-01-01

Multimirror Quartzline Lamps are extremely versatile and effective for nonconventional imaging requirements such as high-speed photo and video instrumentation and high-magnification imaging. The lamps' versatility though, is not limited to conventional environments. Many research experiments and projects require a high pressure environment. Continuous photographic data acquisition in a high-pressure vessel requires wall penetrations and creates design problems as well as potential failure sites. Underwater photography adds the extra consideration of a liquid. This report expands upon the basic research presented in, Performance of Multimirror Quartzline Lamps in High-Pressure Environments, (NASA-TM-83793, Ernie Walker and Howard Slater, 1984). The report provides information to professional industrial, scientific, and technical photographers as well as research personnel on the survivability of lighting a multimirror quartzline lamp in a nonconventional high-pressure underwater environment. Test results of lighted ELH 300 W multimirror quartzline lamps under high-pressure conditions are documented and general information on the lamps' intensity (footcandle output), cone of light coverage, approximate color temperature is provided. Continuous lighting considerations in liquids are also discussed.

Neutron Interrogation System For Underwater Threat Detection And Identification

NASA Astrophysics Data System (ADS)

Barzilov, Alexander P.; Novikov, Ivan S.; Womble, Phil C.

2009-03-01

Wartime and terrorist activities, training and munitions testing, dumping and accidents have generated significant munitions contamination in the coastal and inland waters in the United States and abroad. Although current methods provide information about the existence of the anomaly (for instance, metal objects) in the sea bottom, they fail to identify the nature of the found objects. Field experience indicates that often in excess of 90% of objects excavated during the course of munitions clean up are found to be non-hazardous items (false alarm). The technology to detect and identify waterborne or underwater threats is also vital for protection of critical infrastructures (ports, dams, locks, refineries, and LNG/LPG). We are proposing a compact neutron interrogation system, which will be used to confirm possible threats by determining the chemical composition of the suspicious underwater object. The system consists of an electronic d-T 14-MeV neutron generator, a gamma detector to detect the gamma signal from the irradiated object and a data acquisition system. The detected signal then is analyzed to quantify the chemical elements of interest and to identify explosives or chemical warfare agents.

Use of baited remote underwater video (BRUV) and motion analysis for studying the impacts of underwater noise upon free ranging fish and implications for marine energy management.

PubMed

Roberts, Louise; Pérez-Domínguez, Rafael; Elliott, Michael

2016-11-15

Free-ranging individual fish were observed using a baited remote underwater video (BRUV) system during sound playback experiments. This paper reports on test trials exploring BRUV design parameters, image analysis and practical experimental designs. Three marine species were exposed to playback noise, provided as examples of behavioural responses to impulsive sound at 163-171dB re 1μPa (peak-to-peak SPL) and continuous sound of 142.7dB re 1μPa (RMS, SPL), exhibiting directional changes and accelerations. The methods described here indicate the efficacy of BRUV to examine behaviour of free-ranging species to noise playback, rather than using confinement. Given the increasing concern about the effects of water-borne noise, for example its inclusion within the EU Marine Strategy Framework Directive, and the lack of empirical evidence in setting thresholds, this paper discusses the use of BRUV, and short term behavioural changes, in supporting population level marine noise management. Copyright © 2016 Elsevier Ltd. All rights reserved.

78 FR 60852 - Taking of Marine Mammals Incidental to Specified Activities; Construction of the East Span of the...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-02

... a result of the proposed pile- driving. A detailed description of the acoustic measurements is... measurements, CALTRANS shall establish these zones based on prior measurements conducted during SF-OBB... Driving H-pile NA 1,000 235 95 Dismantling 2,000 NA 100 100 Once the underwater acoustic measurements are...

78 FR 24161 - Takes of Marine Mammals Incidental to Specified Activities; Navy Training Conducted at the Silver...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-24

... one provided here. Comments sent via email, including all attachments, must not exceed a 10-megabyte... due to their light weight, low magnetic signature (in cases of mines sensitive to magnetic fields... underwater detonation training events include one or two detonations. Table 2-1 in the Navy's LOA application...

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...Underwater Acoustic MIMO - OFDM . MIMO - OFDM has been actively studied for high data rate communications over the bandwidthlimited underwater acoustic...with the cochannel interference (CCI) due to parallel transmissions in MIMO - OFDM . Our proposed receiver has the following components: 1

Eddy-Current Non-Inertial Displacement Sensing for Underwater Infrasound Measurements

DTIC Science & Technology

2011-05-01

Eddy-current non-inertial displacement sensing for underwater infrasound measurements Dimitri M. Donskoy Stevens Institute of Technology, 711 Hudson...geophysicists have an ongoing interest in exploring underwater acous- tic processes at infrasound frequencies, for example, for monitoring natural events...underwater infrasound measurements 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f

Human Factors Issues When Operating Underwater Remotely Operated Vehicles and Autonomous Underwater Vehicles

DTIC Science & Technology

2011-03-01

etiquette (Parasuraman & Miller, 2004). Through natural and intuitive communication, Johnson et al., (2007) hope that this interface will instill greater...and etiquette in high criticality automated systems. Communications of the ACM, 47(4), 51-55. Parasuraman, R., & Riley, V. (1997). Humans and... protocols for underwater wireless communications. IEEE Communications Magazine, pp. 97-102. Quazi, A. H., & Konrad, W. L. (1982, March 1982). Underwater

DE-Sync: A Doppler-Enhanced Time Synchronization for Mobile Underwater Sensor Networks.

PubMed

Zhou, Feng; Wang, Qi; Nie, DongHu; Qiao, Gang

2018-05-25

Time synchronization is the foundation of cooperative work among nodes of underwater sensor networks; it takes a critical role in the research and application of underwater sensor networks. Although numerous time synchronization protocols have been proposed for terrestrial wireless sensor networks, they cannot be directly applied to underwater sensor networks. This is because most of them typically assume that the propagation delay among sensor nodes is negligible, which is not the case in underwater sensor networks. Time synchronization is mainly affected by a long propagation delay among sensor nodes due to the low propagation speed of acoustic signals. Furthermore, sensor nodes in underwater tend to experience some degree of mobility due to wind or ocean current, or some other nodes are on self-propelled vehicles, such as autonomous underwater vehicles (AUVs). In this paper, we propose a Doppler-enhanced time synchronization scheme for mobile underwater sensor networks, called DE-Sync. Our new scheme considers the effect of the clock skew during the process of estimating the Doppler scale factor and directly substitutes the Doppler scale factor into linear regression to achieve the estimation of the clock skew and offset. Simulation results show that DE-Sync outperforms existing time synchronization protocols in both accuracy and energy efficiency.

Hearing in the Juvenile Green Sea Turtle (Chelonia mydas): A Comparison of Underwater and Aerial Hearing Using Auditory Evoked Potentials

PubMed Central

Piniak, Wendy E. D.; Mann, David A.; Harms, Craig A.; Jones, T. Todd; Eckert, Scott A.

2016-01-01

Sea turtles spend much of their life in aquatic environments, but critical portions of their life cycle, such as nesting and hatching, occur in terrestrial environments, suggesting that it may be important for them to detect sounds in both air and water. In this study we compared underwater and aerial hearing sensitivities in five juvenile green sea turtles (Chelonia mydas) by measuring auditory evoked potential responses to tone pip stimuli. Green sea turtles detected acoustic stimuli in both media, responding to underwater stimuli between 50 and 1600 Hz and aerial stimuli between 50 and 800 Hz, with maximum sensitivity between 200 and 400 Hz underwater and 300 and 400 Hz in air. When underwater and aerial hearing sensitivities were compared in terms of pressure, green sea turtle aerial sound pressure thresholds were lower than underwater thresholds, however they detected a wider range of frequencies underwater. When thresholds were compared in terms of sound intensity, green sea turtle sound intensity level thresholds were 2–39 dB lower underwater particularly at frequencies below 400 Hz. Acoustic stimuli may provide important environmental cues for sea turtles. Further research is needed to determine how sea turtles behaviorally and physiologically respond to sounds in their environment. PMID:27741231

Hearing in the Juvenile Green Sea Turtle (Chelonia mydas): A Comparison of Underwater and Aerial Hearing Using Auditory Evoked Potentials.

PubMed

Piniak, Wendy E D; Mann, David A; Harms, Craig A; Jones, T Todd; Eckert, Scott A

2016-01-01

Sea turtles spend much of their life in aquatic environments, but critical portions of their life cycle, such as nesting and hatching, occur in terrestrial environments, suggesting that it may be important for them to detect sounds in both air and water. In this study we compared underwater and aerial hearing sensitivities in five juvenile green sea turtles (Chelonia mydas) by measuring auditory evoked potential responses to tone pip stimuli. Green sea turtles detected acoustic stimuli in both media, responding to underwater stimuli between 50 and 1600 Hz and aerial stimuli between 50 and 800 Hz, with maximum sensitivity between 200 and 400 Hz underwater and 300 and 400 Hz in air. When underwater and aerial hearing sensitivities were compared in terms of pressure, green sea turtle aerial sound pressure thresholds were lower than underwater thresholds, however they detected a wider range of frequencies underwater. When thresholds were compared in terms of sound intensity, green sea turtle sound intensity level thresholds were 2-39 dB lower underwater particularly at frequencies below 400 Hz. Acoustic stimuli may provide important environmental cues for sea turtles. Further research is needed to determine how sea turtles behaviorally and physiologically respond to sounds in their environment.

Protocols for Image Processing based Underwater Inspection of Infrastructure Elements

NASA Astrophysics Data System (ADS)

O'Byrne, Michael; Ghosh, Bidisha; Schoefs, Franck; Pakrashi, Vikram

2015-07-01

Image processing can be an important tool for inspecting underwater infrastructure elements like bridge piers and pile wharves. Underwater inspection often relies on visual descriptions of divers who are not necessarily trained in specifics of structural degradation and the information may often be vague, prone to error or open to significant variation of interpretation. Underwater vehicles, on the other hand can be quite expensive to deal with for such inspections. Additionally, there is now significant encouragement globally towards the deployment of more offshore renewable wind turbines and wave devices and the requirement for underwater inspection can be expected to increase significantly in the coming years. While the merit of image processing based assessment of the condition of underwater structures is understood to a certain degree, there is no existing protocol on such image based methods. This paper discusses and describes an image processing protocol for underwater inspection of structures. A stereo imaging image processing method is considered in this regard and protocols are suggested for image storage, imaging, diving, and inspection. A combined underwater imaging protocol is finally presented which can be used for a variety of situations within a range of image scenes and environmental conditions affecting the imaging conditions. An example of detecting marine growth is presented of a structure in Cork Harbour, Ireland.

Robust and underwater superoleophobic coating with excellent corrosion and biofouling resistance in harsh environments

NASA Astrophysics Data System (ADS)

Su, Mingji; Liu, Yong; Zhang, Yuhong; Wang, Zhiguo; Li, Yulin; He, Peixin

2018-04-01

Underwater superoleophobic surfaces are based on the surface with micro-/nanoscale roughness and hydration layer. But the self-cleaning surfaces are usually mechanically weak and will lose their underwater superoleophobicity when the surfaces are corroded or damaged. In this paper, to overcome these problems, the robust underwater superoleophobic coating (HN/ER-coating) has been fabricated successfully through MPS (methacryloxy propyl trimethoxyl silane)-SiO2/PNIPAM (N-isopropylacryamide) hybrid nanoparticles and epoxy resin (ER) via a simple solution-casting method. The SiO2/PNIPAM hybrid nanoparticles can enhance multiscale roughness and excellent abrasion-resistant property, and the epoxy resin can be used as an interlayer between hybrid nanoparticles and substrates to promote the robustness and corrosion resistance of the coating. The obtained coatings have excellent underwater superoleophobicity, and exhibit highly stability in harsh environments (including acid-base, strong ionic strength, mechanical abrasion). Moreover, this coating can provide protective effect on the substrate in corrosive solution, and may also resist bacterial attachment and subsequent biofilm formation because of the presence of high density PNIPAM polymers. Herein, the developed underwater superoleophobic coating can be applied as an effective platform for the applications in underwater instruments, underwater oil transport, marine oil platform and ships.

Comparison of conventional and self-consolidating concrete for drilled shaft construction.

DOT National Transportation Integrated Search

2015-04-01

Many entities currently use self-consolidating concrete (SCC), especially for drilled shaft construction. This project investigated the use of SCC : and various test methods to assess the suitability of SCC in underwater placement conditions. Eight m...

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

Astro Stars Camp features underwater robotics

NASA Image and Video Library

2010-06-29

Ian Tonglet, 13, (left) and Seth Malley, 13, both of Picayune, Miss., and both participants in the 2010 Astro Stars session at Stennis Space Center, work with an underwater robot during a camp activity June 29. NASA joined with the U.S. Navy for the underwater robotics exercise involving Sea Perch robots, which are simple, remotely operated underwater vehicles made from PVC pipe and other inexpensive, easily available materials. During the Stennis exercise, students used robots constructed earlier in the day to maneuver underwater and collect plastic rings, as seen to the left of Tonglet. Astro STARS (Spaceflight, Technology, Astronomy & Robotics @ Stennis) is a science and technology camp for 13-15 year olds.

Award 1 Title: Acoustic Communications 2011 Experiment: Deployment Support and Post Experiment Data Handling and Analysis. Award 2 Title: Exploiting Structured Dependencies in the Design of Adaptive Algorithms for Underwater Communication Award. 3 Title: Coupled Research in Ocean Acoustics and Signal Processing for the Next Generation of Underwater Acoustic Communication Systems

DTIC Science & Technology

2015-09-30

Wireless Networks (WUWNet’14), Rome, Italy, Nov. 12 ­ 14, 2014. J. Preisig, “ Underwater Acoustic Communications: Enabling the Next Generation at the...on Wireless Communication. M. Pajovic, J. Preisig, “Performance Analytics and Optimal Design of Multichannel Equalizers for Underwater Acoustic Communications”, to appear in IEEE Journal of Oceanic Engineering. 6 ...Exploiting Structured Dependencies in the Design of Adaptive Algorithms for Underwater Communication Award #3

Advanced instrumentation for research in diving and hyperbaric medicine.

PubMed

Sieber, Arne; L'Abbate, Antonio; Kuch, Benjamin; Wagner, Matthias; Benassi, Antonio; Passera, Mirko; Bedini, Remo

2010-01-01

Improving the safety of diving and increasing knowledge about the adaptation of the human body to underwater and hyperbaric environment require specifically developed underwater instrumentation for physiological measurements. In fact, none of the routine clinical devices for health control is suitable for in-water and/or under-pressure operation. The present paper addresses novel technological acquisitions and the development of three dedicated devices: * an underwater data logger for recording O2 saturation (reflective pulsoxymetry), two-channel ECG, depth and temperature; * an underwater blood pressure meter based on the oscillometric method; and * an underwater echography system. Moreover, examples of recordings are presented and discussed.

Underwater cleaning techniqued used for removal of zebra mussels at the FitzPatrick Nuclear Power Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hobbs, B.; Kahabka, J.

1995-06-01

This paper discusses the use of a mechanical brush cleaning technology recently used to remove biofouling from the Circulating Water (CW) System at New York Power Authority`s James A. FitzPatrick Nuclear Power Plant. The FitzPatrick plant had previously used chemical molluscicide to treat zebra mussels in the CW system. Full system treatment was performed in 1992 with limited forebay/screenwell treatment in 1993. The New York Power Authority (NYPA) decided to conduct a mechanical cleaning of the intake system in 1994. Specific project objectives included: (1) Achieve a level of surface cleaniness greater than 98%; (2) Remove 100% of debris, bothmore » existing sediment and debris generated as a result of cleaning; (3) Inspect all surfaces and components, identifying any problem areas; (4) Complete the task in a time frame within the 1994-95 refueling outage schedule window, and; (5) Determine if underwater mechanical cleaning is a cost-effective zebra mussel control method suitable for future application at FitzPatrick. A pre-cleaning inspection, including underwater video photography, was conducted of each area. Cleaning was accomplished using diver-controlled, multi-brush equipment included the electro-hydraulic powered Submersible Cleaning and Maintenance Platform (SCAMP), and several designs of hand-held machines. The brushes swept all zebra mussels off surfaces, restoring concrete and metal substrates to their original condition. Sensitive areas including pump housings, standpipes, sensor piping and chlorine injection tubing, were cleaned without degradation. Submersible vortex vacuum pumps were used to remove debris from the cavity. More than 46,000 ft{sup 2} of surface area was cleaned and over 460 cubic yards of dewatered debris were removed. As each area was completed, a post-clean inspection with photos and video was performed.« less

Locating underwater objects. [technology transfer

NASA Technical Reports Server (NTRS)

Grice, C. F.

1974-01-01

Underwater search operations are considered to be engineering and operational problems. A process for proper definition of the problem and selection of instrumentation and operational procedures is described. An outline of underwater search instrumentation and techniques is given.

Optical turbulence on underwater image degradation in natural environments.

PubMed

Hou, Weilin; Woods, Sarah; Jarosz, Ewa; Goode, Wesley; Weidemann, Alan

2012-05-10

It is a well-known fact that the major degradation source on electro-optical imaging underwater is from scattering by particles of various origins and sizes. Recent research indicates that, under certain conditions, the apparent degradation could also be caused by the variations of index of refraction associated with temperature and salinity microstructures in the ocean and lakes. The combined impact has been modeled previously through the simple underwater imaging model. The current study presents the first attempts in quantifying the level of image degradation due to optical turbulence in natural waters in terms of modulation transfer functions using measured turbulence dissipation rates. Image data collected from natural environments during the Skaneateles Optical Turbulence Exercise are presented. Accurate assessments of the turbulence conditions are critical to the model validation and were measured by two instruments to ensure consistency and accuracy. Optical properties of the water column in the field were also measured in coordination with temperature, conductivity, and depth. The results show that optical turbulence degrades the image quality as predicted and on a level comparable to that caused by the particle scattering just above the thermocline. Other contributing elements involving model closure, including temporal and spatial measurement scale differences among sensors and mitigation efforts, are discussed.

Design of underwater robot lines based on a hybrid automatic optimization strategy

NASA Astrophysics Data System (ADS)

Lyu, Wenjing; Luo, Weilin

2014-09-01

In this paper, a hybrid automatic optimization strategy is proposed for the design of underwater robot lines. Isight is introduced as an integration platform. The construction of this platform is based on the user programming and several commercial software including UG6.0, GAMBIT2.4.6 and FLUENT12.0. An intelligent parameter optimization method, the particle swarm optimization, is incorporated into the platform. To verify the strategy proposed, a simulation is conducted on the underwater robot model 5470, which originates from the DTRC SUBOFF project. With the automatic optimization platform, the minimal resistance is taken as the optimization goal; the wet surface area as the constraint condition; the length of the fore-body, maximum body radius and after-body's minimum radius as the design variables. With the CFD calculation, the RANS equations and the standard turbulence model are used for direct numerical simulation. By analyses of the simulation results, it is concluded that the platform is of high efficiency and feasibility. Through the platform, a variety of schemes for the design of the lines are generated and the optimal solution is achieved. The combination of the intelligent optimization algorithm and the numerical simulation ensures a global optimal solution and improves the efficiency of the searching solutions.

Navigation by light polarization in clear and turbid waters

PubMed Central

Lerner, Amit; Sabbah, Shai; Erlick, Carynelisa; Shashar, Nadav

2011-01-01

Certain terrestrial animals use sky polarization for navigation. Certain aquatic species have also been shown to orient according to a polarization stimulus, but the correlation between underwater polarization and Sun position and hence the ability to use underwater polarization as a compass for navigation is still under debate. To examine this issue, we use theoretical equations for per cent polarization and electric vector (e-vector) orientation that account for the position of the Sun, refraction at the air–water interface and Rayleigh single scattering. The polarization patterns predicted by these theoretical equations are compared with measurements conducted in clear and semi-turbid coastal sea waters at 2 m and 5 m depth over sea floors of 6 m and 28 m depth. We find that the per cent polarization is correlated with the Sun's elevation only in clear waters. We furthermore find that the maximum value of the e-vector orientation angle equals the angle of refraction only in clear waters, in the horizontal viewing direction, over the deeper sea floor. We conclude that navigation by use of underwater polarization is possible under restricted conditions, i.e. in clear waters, primarily near the horizontal viewing direction, and in locations where the sea floor has limited effects on the light's polarization. PMID:21282170

Stable aqueous dispersions of functionalized multi-layer graphene by pulsed underwater plasma exfoliation of graphite

NASA Astrophysics Data System (ADS)

Meyer-Plath, Asmus; Beckert, Fabian; Tölle, Folke J.; Sturm, Heinz; Mülhaupt, Rolf

2016-02-01

A process was developed for graphite particle exfoliation in water to stably dispersed multi-layer graphene. It uses electrohydraulic shockwaves and the functionalizing effect of solution plasma discharges in water. The discharges were excited by 100 ns high voltage pulsing of graphite particle chains that bridge an electrode gap. The underwater discharges allow simultaneous exfoliation and chemical functionalization of graphite particles to partially oxidized multi-layer graphene. Exfoliation is caused by shockwaves that result from rapid evaporation of carbon and water to plasma-excited gas species. Depending on discharge energy and locus of ignition, the shockwaves cause stirring, erosion, exfoliation and/or expansion of graphite flakes. The process was optimized to produce long-term stable aqueous dispersions of multi-layer graphene from graphite in a single process step without requiring addition of intercalants, surfactants, binders or special solvents. A setup was developed that allows continuous production of aqueous dispersions of flake size-selected multi-layer graphenes. Due to the well-preserved sp2-carbon structure, thin films made from the dispersed graphene exhibited high electrical conductivity. Underwater plasma discharge processing exhibits high innovation potential for morphological and chemical modifications of carbonaceous materials and surfaces, especially for the generation of stable dispersions of two-dimensional, layered materials.

Underwater Photogrammetry and 3d Reconstruction of Marble Cargos Shipwreck

NASA Astrophysics Data System (ADS)

Balletti, C.; Beltrame, C.; Costa, E.; Guerra, F.; Vernier, P.

2015-04-01

Nowadays archaeological and architectural surveys are based on the acquisition and processing of point clouds, allowing a high metric precision, essential prerequisite for a good documentation. Digital image processing and laser scanner have changed the archaeological survey campaign, from manual and direct survey to a digital one and, actually, multi-image photogrammetry is a good solution for the underwater archaeology. This technical documentation cannot operate alone, but it has to be supported by a topographical survey to georeference all the finds in the same reference system. In the last years the Ca' Foscari and IUAV University of Venice are conducting a research on integrated survey techniques to support underwater metric documentation. The paper will explain all the phases regarding the survey's design, images acquisition, topographic measure and the data processing of two Roman shipwrecks in south Sicily. The cargos of the shipwrecks are composed by huge marble blocks, but they are different for morphological characteristic of the sites, for the depth and for their distribution on the seabed. Photogrammetrical and topographical surveys were organized in two distinct methods, especially for the second one, due to the depth that have allowed an experimentation of GPS RTK's measurements on one shipwreck. Moreover, this kind of three-dimensional documentation is useful for educational and dissemination aspect, for the ease of understanding by wide public.

King County Nearshore Habitat Mapping Data Report: Picnic Point to Shilshole Bay Marina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woodruff, Dana L.; Farley, Paul J.; Borde, Amy B.

2000-12-31

The objective of this study is to provide accurate, georeferenced maps of benthic habitats to assist in the siting of a new wastewater treatment plant outfall and the assessment of habitats of endangered, threatened, and economically important species. The mapping was conducted in the fall of 1999 using two complementary techniques: side-scan sonar and underwater videography. Products derived from these techniques include geographic information system (GIS) compatible polygon data of substrate type and vegetation cover, including eelgrass and kelp. Additional GIS overlays include underwater video track line data of total macroalgae, selected macroalgal species, fish, and macroinvertebrates. The combined toolsmore » of geo-referenced side-scan sonar and underwater video is a powerful technique for assessing and mapping of nearshore habitat in Puget Sound. Side-scan sonar offers the ability to map eelgrass with high spatial accuracy and resolution, and provides information on patch size, shape, and coverage. It also provides information on substrate change and location of specific targets (e.g., piers, docks, pilings, large boulders, debris piles). The addition of underwater video is a complementary tool providing both groundtruthing for the sonar and additional information on macro fauna and flora. As a groundtruthing technique, the video was able to confirm differences between substrate types, as well as detect subtle spatial changes in substrate. It also verified information related to eelgrass, including the density classification categories and the type of substrate associated with eelgrass, which could not be determined easily with side- scan sonar. Video is also a powerful tool for mapping the location of macroalgae, (including kelp and Ulva), fish and macroinvertebrates. The ability to geo-locate these resources in their functional habitat provides an added layer of information and analytical potential.« less

Feasibility of Underwater Friction Stir Welding of HY-80 Steel

DTIC Science & Technology

2011-03-01

UNDERWATER FRICTION STIR WELDING OF HY-80 STEEL by William C. Stewart March 2011 Thesis Advisor: Terry McNelley Second Reader: Sarath Menon...Master’s Thesis 4. TITLE AND SUBTITLE Feasibility of Underwater Friction Stir Welding of HY-80 Steel 5. FUNDING NUMBERS 6. AUTHOR(S) William...DISTRIBUTION CODE A 13. ABSTRACT (maximum 200 words) The purpose of this thesis is to determine the feasibility of underwater friction stir welding

Topology Optimization for Energy Management in Underwater Sensor Networks

DTIC Science & Technology

2015-02-01

1 To appear in International Journal of Control as a regular paper Topology Optimization for Energy Management in Underwater Sensor Networks ⋆ Devesh...K. Jha1 Thomas A. Wettergren2 Asok Ray1 Kushal Mukherjee3 Keywords: Underwater Sensor Network , Energy Management, Pareto Optimization, Adaptation...Optimization for Energy Management in Underwater Sensor Networks 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d

The Effect of Underwater Gait Training on Balance Ability of Stroke Patients

PubMed Central

Park, Seok Woo; Lee, Kyoung Jin; Shin, Doo Chul; Shin, Seung Ho; Lee, Myung Mo; Song, Chang Ho

2014-01-01

[Purpose] The purpose of this study was to investigate the effects of underwater treadmill gait training on the balance ability of stroke patients. [Subjects] Twenty-two patients with stroke were randomly assigned to an underwater treadmill group (n =11) or a control group (n =11). [Methods] Both groups received general rehabilitation for 30 min per session, 5 times per week, over a 4-week period. The underwater treadmill group received additional underwater gait training for 30 min per session, 5 times per week, over the same 4-week period. Static and dynamic balances were evaluated before and after the intervention. [Results] The means of static and dynamic balance ability increased significantly in both groups, but there was no significant difference between the two groups. [Conclusion] Compared to the general rehabilitation program, underwater treadmill gait training was not more effective at improving the balance ability of stroke patients than land-based training. PMID:25013292

A novel underwater dam crack detection and classification approach based on sonar images

PubMed Central

Shi, Pengfei; Fan, Xinnan; Ni, Jianjun; Khan, Zubair; Li, Min

2017-01-01

Underwater dam crack detection and classification based on sonar images is a challenging task because underwater environments are complex and because cracks are quite random and diverse in nature. Furthermore, obtainable sonar images are of low resolution. To address these problems, a novel underwater dam crack detection and classification approach based on sonar imagery is proposed. First, the sonar images are divided into image blocks. Second, a clustering analysis of a 3-D feature space is used to obtain the crack fragments. Third, the crack fragments are connected using an improved tensor voting method. Fourth, a minimum spanning tree is used to obtain the crack curve. Finally, an improved evidence theory combined with fuzzy rule reasoning is proposed to classify the cracks. Experimental results show that the proposed approach is able to detect underwater dam cracks and classify them accurately and effectively under complex underwater environments. PMID:28640925

A novel underwater dam crack detection and classification approach based on sonar images.

PubMed

Shi, Pengfei; Fan, Xinnan; Ni, Jianjun; Khan, Zubair; Li, Min

2017-01-01

Underwater dam crack detection and classification based on sonar images is a challenging task because underwater environments are complex and because cracks are quite random and diverse in nature. Furthermore, obtainable sonar images are of low resolution. To address these problems, a novel underwater dam crack detection and classification approach based on sonar imagery is proposed. First, the sonar images are divided into image blocks. Second, a clustering analysis of a 3-D feature space is used to obtain the crack fragments. Third, the crack fragments are connected using an improved tensor voting method. Fourth, a minimum spanning tree is used to obtain the crack curve. Finally, an improved evidence theory combined with fuzzy rule reasoning is proposed to classify the cracks. Experimental results show that the proposed approach is able to detect underwater dam cracks and classify them accurately and effectively under complex underwater environments.

Homogeneity of Mechanical Properties of Underwater Friction Stir Welded 2219-T6 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Liu, H. J.; Zhang, H. J.; Yu, L.

2011-11-01

Underwater friction stir welding (FSW) has been demonstrated to be available for the improvement in tensile strength of normal FSW joints. In order to illuminate the intrinsic reason for strength improvement through underwater FSW, a 2219 aluminum alloy was underwater friction stir welded and the homogeneity of mechanical properties of the joint was investigated by dividing the joint into three layers. The results indicate that the tensile strength of the three layers of the joint is all improved by underwater FSW, furthermore, the middle and lower layers have larger extent of strength improvement than the upper layer, leading to an increase in the homogeneity of mechanical properties of the joint. The minimum hardness value of each layer, especially the middle and lower layers, is improved under the integral water cooling effect, which is the intrinsic reason for the strength improvement of underwater joint.

Optimal diving behaviour and respiratory gas exchange in birds.

PubMed

Halsey, Lewis G; Butler, Patrick J

2006-11-01

This review discusses the advancements in our understanding of the physiology and behaviour of avian diving that have been underpinned by optimal foraging theory and the testing of optimal models. To maximise their foraging efficiency during foraging periods, diving birds must balance numerous factors that are directly or indirectly related to the replenishment of the oxygen stores and the removal of excess carbon dioxide. These include (1) the time spent underwater (which diminishes the oxygen supply, increases carbon dioxide levels and may even include a build up of lactate due to anaerobic metabolism), (2) the time spent at the surface recovering from the previous dive and preparing for the next (including reloading their oxygen supply, decreasing their carbon dioxide levels and possibly also metabolising lactate) and (3) the trade-off between maximising oxygen reserves for consumption underwater by taking in more air to the respiratory system, and minimising the energy costs of positive buoyancy caused by this air, to maximise the time available underwater to forage. Due to its importance in avian diving, replenishment of the oxygen stores has become integral to models of optimal diving, which predict the time budgeting of animals foraging underwater. While many of these models have been examined qualitatively, such tests of predictive trends appear fallible and only quantifiable support affords strong evidence of their predictive value. This review describes how the quantification of certain optimal diving models, using tufted ducks, indeed demonstrates some predictive success. This suggests that replenishment of the oxygen stores and removal of excess carbon dioxide have significant influences on the duration of the surface period between dives. Nevertheless, present models are too simplistic to be robust predictors of diving behaviour for individual animals and it is proposed that they require refinement through the incorporation of other variables that also influence diving behaviour such as, perhaps, prey density and predator avoidance.

Underwater gait analysis in Parkinson's disease.

PubMed

Volpe, Daniele; Pavan, Davide; Morris, Meg; Guiotto, Annamaria; Iansek, Robert; Fortuna, Sofia; Frazzitta, Giuseppe; Sawacha, Zimi

2017-02-01

Although hydrotherapy is one of the physical therapies adopted to optimize gait rehabilitation in people with Parkinson disease, the quantitative measurement of gait-related outcomes has not been provided yet. This work aims to document the gait improvements in a group of parkinsonians after a hydrotherapy program through 2D and 3D underwater and on land gait analysis. Thirty-four parkinsonians and twenty-two controls were enrolled, divided into two different cohorts. In the first one, 2 groups of patients underwent underwater or land based walking training; controls underwent underwater walking training. Hence pre-treatment 2D underwater and on land gait analysis were performed, together with post-treatment on land gait analysis. Considering that current literature documented a reduced movement amplitude in parkinsonians across all lower limb joints in all movement planes, 3D underwater and on land gait analysis were performed on a second cohort of subjects (10 parkinsonians and 10 controls) who underwent underwater gait training. Baseline land 2D and 3D gait analysis in parkinsonians showed shorter stride length and slower speed than controls, in agreement with previous findings. Comparison between underwater and on land gait analysis showed reduction in stride length, cadence and speed on both parkinsonians and controls. Although patients who underwent underwater treatment exhibited significant changes on spatiotemporal parameters and sagittal plane lower limb kinematics, 3D gait analysis documented a significant (p<0.05) improvement in all movement planes. These data deserve attention for research directions promoting the optimal recovery and maintenance of walking ability. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Design and Application of New Low-Cost Instruments for Marine Environmental Research

PubMed Central

Marcelli, Marco; Piermattei, Viviana; Madonia, Alice; Mainardi, Umberto

2014-01-01

The development of low-cost instrumentation plays a key role in marine environmental studies and represents one of the most innovative aspects of current oceanographic research. These kinds of devices can be used for several applications, ranging from vertical profilers to stand-alone systems, and can be installed on different platforms (buoys, Voluntary Observing Ships, underwater vehicles, etc.). The availability of low-cost technologies enables the realization of extended observatory networks for the study of marine physical and biological processes through an integrated approach merging in situ observations, forecasting models and remotely sensed data. We present new low-cost sensors and probes developed to measure marine temperature, conductivity, chlorophyll a and Chromophoric Dissolved Organic Matter fluorescence, focusing on sensing strategies, general architecture, laboratory trials, in situ tests and comparison with standard instruments. Furthermore, we report the expendable (New T-FLaP), vertical profiler (T-FLaPpro) and stand-alone (Spectra) applications of these technological developments that were tested during several oceanographic surveys in the Mediterranean Sea. PMID:25490594

Experimental study of a DMD based compressive line sensing imaging system in the turbulence environment

NASA Astrophysics Data System (ADS)

Ouyang, Bing; Hou, Weilin; Gong, Cuiling; Caimi, Frank M.; Dalgleish, Fraser R.; Vuorenkoski, Anni K.

2016-05-01

The Compressive Line Sensing (CLS) active imaging system has been demonstrated to be effective in scattering mediums, such as turbid coastal water through simulations and test tank experiments. Since turbulence is encountered in many atmospheric and underwater surveillance applications, a new CLS imaging prototype was developed to investigate the effectiveness of the CLS concept in a turbulence environment. Compared with earlier optical bench top prototype, the new system is significantly more robust and compact. A series of experiments were conducted at the Naval Research Lab's optical turbulence test facility with the imaging path subjected to various turbulence intensities. In addition to validating the system design, we obtained some unexpected exciting results - in the strong turbulence environment, the time-averaged measurements using the new CLS imaging prototype improved both SNR and resolution of the reconstructed images. We will discuss the implications of the new findings, the challenges of acquiring data through strong turbulence environment, and future enhancements.

Design and application of new low-cost instruments for marine environmental research.

PubMed

Marcelli, Marco; Piermattei, Viviana; Madonia, Alice; Mainardi, Umberto

2014-12-05

The development of low-cost instrumentation plays a key role in marine environmental studies and represents one of the most innovative aspects of current oceanographic research. These kinds of devices can be used for several applications, ranging from vertical profilers to stand-alone systems, and can be installed on different platforms (buoys, Voluntary Observing Ships, underwater vehicles, etc.). The availability of low-cost technologies enables the realization of extended observatory networks for the study of marine physical and biological processes through an integrated approach merging in situ observations, forecasting models and remotely sensed data. We present new low-cost sensors and probes developed to measure marine temperature, conductivity, chlorophyll a and Chromophoric Dissolved Organic Matter fluorescence, focusing on sensing strategies, general architecture, laboratory trials, in situ tests and comparison with standard instruments. Furthermore, we report the expendable (New T-FLaP), vertical profiler (T-FLaPpro) and stand-alone (Spectra) applications of these technological developments that were tested during several oceanographic surveys in the Mediterranean Sea.

15 CFR 922.190 - Boundary.

Code of Federal Regulations, 2012 CFR

2012-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922.190 Boundary. The Thunder Bay National Marine Sanctuary and Underwater Preserve (Sanctuary) consists... submerged lands thereunder, over, around, and under the underwater cultural resources in Thunder Bay. The...

15 CFR 922.190 - Boundary.

Code of Federal Regulations, 2013 CFR

2013-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922.190 Boundary. The Thunder Bay National Marine Sanctuary and Underwater Preserve (Sanctuary) consists... submerged lands thereunder, over, around, and under the underwater cultural resources in Thunder Bay. The...

15 CFR 922.190 - Boundary.

Code of Federal Regulations, 2014 CFR

2014-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922.190 Boundary. The Thunder Bay National Marine Sanctuary and Underwater Preserve (Sanctuary) consists... submerged lands thereunder, over, around, and under the underwater cultural resources in Thunder Bay. The...

15 CFR 922.190 - Boundary.

Code of Federal Regulations, 2010 CFR

2010-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922.190 Boundary. The Thunder Bay National Marine Sanctuary and Underwater Preserve (Sanctuary) consists... submerged lands thereunder, over, around, and under the underwater cultural resources in Thunder Bay. The...

15 CFR 922.190 - Boundary.

Code of Federal Regulations, 2011 CFR

2011-01-01

... MARINE SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve § 922.190 Boundary. The Thunder Bay National Marine Sanctuary and Underwater Preserve (Sanctuary) consists... submerged lands thereunder, over, around, and under the underwater cultural resources in Thunder Bay. The...

Priority Determination of Underwater Tourism Site Development in Gorontalo Province using Analytical Hierarchy Process (AHP)

NASA Astrophysics Data System (ADS)

Rohandi, M.; Tuloli, M. Y.; Jassin, R. T.

2018-02-01

This research aims to determine the development of priority of underwater tourism in Gorontalo province using the Analytical Hierarchy Process (AHP) method which is one of DSS methods applying Multi-Attribute Decision Making (MADM). This method used 5 criteria and 28 alternatives to determine the best priority of underwater tourism site development in Gorontalo province. Based on the AHP calculation it appeared that the best priority development of underwater tourism site is Pulau Cinta whose total AHP score is 0.489 or 48.9%. This DSS produced a reliable result, faster solution, time-saving, and low cost for the decision makers to obtain the best underwater tourism site to be developed.

Chinese research on underwater acoustics

NASA Astrophysics Data System (ADS)

Qian, Zhengxu; Ding, Dong

1992-09-01

The monograph provides a baseline assessment of Chinese literature in research on the physics and technology of underwater acoustics during the last decade in China. However, developments prior to 1980 are also briefly covered, as they provide background and context for recent developments. This report will provide the following: (1) a description of research organizations and their administrative structure, professional societies, conferences, researchers, and engineers; (2) a technical review of the physics and engineering of underwater acoustics; (3) a list of underwater acoustics experts from the United States and Europe who visited China; (4) a list of underwater acoustics monography written by Chinese authors; and (5) a brief assessment of the Chinese research at the international level.

Efficient Use of AUVs in the Maritime Environment

NASA Astrophysics Data System (ADS)

Slămnoiu, G.; Radu, O.; Roşca, V.; Pascu, C.; Surdu, G.; Curcă, E.; Damian, R. G.; Rădulescu, A.

2017-06-01

Autonomous underwater vehicle (AUV) a.k.a. underwater drones are subsea vehicles which operate in the underwater environment independently of direct human input. There is a growing interest in underwater data collection by using autonomous underwater vehicles within the oceanographic research community. In this paper, the Iver 2 AUV is examined to accomplish accurate side-scan data while executing well planned missions. Therefore, this papers goal is to establish the optimal use conditions for the AUV that RCN has so that we maximize the detection probability of sea bottom objects that can be risk factors and at the same time to cover a surface as large as possible during a single mission.

Underwater sympathetic detonation of pellet explosive

NASA Astrophysics Data System (ADS)

Kubota, Shiro; Saburi, Tei; Nagayama, Kunihito

2017-06-01

The underwater sympathetic detonation of pellet explosives was taken by high-speed photography. The diameter and the thickness of the pellet were 20 and 10 mm, respectively. The experimental system consists of the precise electric detonator, two grams of composition C4 booster and three pellets, and these were set in water tank. High-speed video camera, HPV-X made by Shimadzu was used with 10 Mfs. The underwater explosions of the precise electric detonator, the C4 booster and a pellet were also taken by high-speed photography to estimate the propagation processes of the underwater shock waves. Numerical simulation of the underwater sympathetic detonation of the pellet explosives was also carried out and compared with experiment.

A review of underwater bio-mimetic propulsion: cruise and fast-start

NASA Astrophysics Data System (ADS)

Chao, Li-Ming; Cao, Yong-Hui; Pan, Guang

2017-08-01

This paper reviews recent developments in the understanding of underwater bio-mimetic propulsion. Two impressive models of underwater propulsion are considered: cruise and fast-start. First, we introduce the progression of bio-mimetic propulsion, especially underwater propulsion, where some primary conceptions are touched upon. Second, the understanding of flapping foils, considered as one of the most efficient cruise styles of aquatic animals, is introduced, where the effect of kinematics and the shape and flexibility of foils on generating thrust are elucidated respectively. Fast-start propulsion is always exhibited when predator behaviour occurs, and we provide an explicit introduction of corresponding zoological experiments and numerical simulations. We also provide some predictions about underwater bio-mimetic propulsion.

How many fish? Comparison of two underwater visual sampling methods for monitoring fish communities

PubMed Central

Sini, Maria; Vatikiotis, Konstantinos; Katsoupis, Christos

2018-01-01

Background Underwater visual surveys (UVSs) for monitoring fish communities are preferred over fishing surveys in certain habitats, such as rocky or coral reefs and seagrass beds and are the standard monitoring tool in many cases, especially in protected areas. However, despite their wide application there are potential biases, mainly due to imperfect detectability and the behavioral responses of fish to the observers. Methods The performance of two methods of UVSs were compared to test whether they give similar results in terms of fish population density, occupancy, species richness, and community composition. Distance sampling (line transects) and plot sampling (strip transects) were conducted at 31 rocky reef sites in the Aegean Sea (Greece) using SCUBA diving. Results Line transects generated significantly higher values of occupancy, species richness, and total fish density compared to strip transects. For most species, density estimates differed significantly between the two sampling methods. For secretive species and species avoiding the observers, the line transect method yielded higher estimates, as it accounted for imperfect detectability and utilized a larger survey area compared to the strip transect method. On the other hand, large-scale spatial patterns of species composition were similar for both methods. Discussion Overall, both methods presented a number of advantages and limitations, which should be considered in survey design. Line transects appear to be more suitable for surveying secretive species, while strip transects should be preferred at high fish densities and for species of high mobility. PMID:29942703

76 FR 52734 - Underwater Locating Devices (Acoustic) (Self-Powered)

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-23

...This notice announces the planned revocation of all Technical Standard Order authorizations (TSOA) issued for the production of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured to the TSO-C121 and TSO-C121a specifications. These actions are necessary because the planned issuance of TSO-C121b, Underwater Locating Devices (Acoustic) (Self-Powered), with a minimum performance standard (MPS) that will increase the minimum operating life of Underwater Locating Devices from 30 days to 90 days.

77 FR 13174 - Underwater Locating Devices (Acoustic) (Self-Powered)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-05

...This is a confirmation notice for the planned revocation of all Technical Standard Order authorizations issued for the production of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured to the TSO-C121 and TSO-C121a specifications. These actions are necessary because the planned issuance of TSO-C121b, Underwater Locating Devices (Acoustic) (Self-Powered), minimum performance standard (MPS) will increase the minimum operating life of Underwater Locating Devices from 30 days to 90 days.

Spatial-Gain Improvement Resulting from Left/Right Discriminating Elements of an Underwater Towed Array

DTIC Science & Technology

1981-09-15

DISCRIMINATING ELEMENTS OF AN UNDERWATER TOWED ARRAY rsil RONALD A. WAGSTAFF and PIETRO MANASCA D TIC": L• ’" .... 4"•’.,, 15 SEPTEMBER 1981...IMPROVEMENT RESULTING FROM LEFT/RIGHT DISCRIMINATING ELEMENTS OF AN UNDERWATER TOWED ARRAY by Ronald A. Wagstaff and Pietro Zanasca 15 September 1981 F...RESULTING FROM LEFT/RIGHT DISCRIMINATING ELEMENTS OF AN UNDERWATER TOWED ARRAY by Ronald A. Wagstaff and Pietro Zanasca ABSTRACT The improvement in

Results from an Integrated Optical/Acoustic Communication System Installed at CORK 857D: Implications for Future Seafloor Observatories

NASA Astrophysics Data System (ADS)

Tivey, M.; Farr, N.; Ware, J.; Pontbriand, C.

2011-12-01

A CORK (Circulation Obviation Retrofit Kit) borehole represents all of the basic components required for a seafloor observatory: a stable environment for long-term continuous measurements of earth and ocean phenomena, access to a unique environment below the seafloor under controlled conditions (e.g. hydrologically sealed), and a standard interface for communication. Typically, however, due to power constraints and a limited frequency of data download opportunities, data sampling has been limited to rates on the order of several minutes. For full seismic wave sampling, at least 1 Hz or better is required. While some CORK systems are now being connected to an underwater cable to provide continuous power and real-time data (cf. Neptune network in the Northeast Pacific), there will be locations where cabled observatories are not viable. Another mode of communication is required to enable both high data rate communication and access for data download via more conventional vessels and not limited to those with ROV or submersibles. We here report on technology to enable high data rate download and transfer of data and information using underwater optical communications, which can be accomplished from a surface vessel of opportunity or, in the future, by autonomous underwater vehicle. In 2010, we successfully deployed and tested an underwater optical communication system that provides high data rate communications over a range of 100 meters from a deep sea CORK borehole observatory located in the northeast Pacific at IODP Hole 857D. The CORK is instrumented with a thermistor string and pressure sensors that record downhole formation pressures and temperatures within oceanic basement and is pressure sealed from the overlying water column. The seafloor Optical Telemetry System (OTS) was plugged into the CORK's existing underwater matable connector to provide an optical and acoustic communication interface and additional data storage and battery power for the CORK to sample at 1 Hz data-rate, an increase over the normal 15 sec data sample rate. A CTD-mounted OTS lowered by wire from a surface ship established an optical communication link at 100 meters range at rates of 1, 5 and 10 Mbps with no bit errors. This mode of communication demonstrates the effectiveness of using a ship-based system to interrogate the system remotely. The OTS was designed to be installed at the seafloor CORK for a year. In 2011, we will revisit the CORK and OTS using the ROV Jason to test the system, download the data collected during this period and to refurbish the batteries for a further year-long deployment period. We will report on the results of those tests at the meeting. As the need to observe oceanic and earth phenomenon over periods not limited to weather windows or cruise schedules increases, the borehole observatory will provide an important venue for gaining access to such timescales. High data-rate underwater communications will be required to make full use of such observatory infrastructure. The use of free water optical communication methods provides a logical way to accomplish these goals in the future.

Looking into the water with oblique head tilting: revision of the aerial binocular imaging of underwater objects.

PubMed

Horváth, Gábor; Buchta, Krisztián; Varjú, Dezsö

2003-06-01

It is a well-known phenomenon that when we look into the water with two aerial eyes, both the apparent position and the apparent shape of underwater objects are different from the real ones because of refraction at the water surface. Earlier studies of the refraction-distorted structure of the underwater binocular visual field of aerial observers were restricted to either vertically or horizontally oriented eyes. We investigate a generalized version of this problem: We calculate the position of the binocular image point of an underwater object point viewed by two arbitrarily positioned aerial eyes, including oblique orientations of the eyes relative to the flat water surface. Assuming that binocular image fusion is performed by appropriate vergent eye movements to bring the object's image onto the foveas, the structure of the underwater binocular visual field is computed and visualized in different ways as a function of the relative positions of the eyes. We show that a revision of certain earlier treatments of the aerial imaging of underwater objects is necessary. We analyze and correct some widespread erroneous or incomplete representations of this classical geometric optical problem that occur in different textbooks. Improving the theory of aerial binocular imaging of underwater objects, we demonstrate that the structure of the underwater binocular visual field of aerial observers distorted by refraction is more complex than has been thought previously.

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.

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.

Instrumenting free-swimming dolphins echolocating in open water.

PubMed

Martin, Stephen W; Phillips, Michael; Bauer, Eric J; Moore, Patrick W; Houser, Dorian S

2005-04-01

Dolphins within the Navy Marine Mammal Program use echolocation to effectively locate underwater mines. They currently outperform manmade systems at similar tasks, particularly in cluttered environments and on buried targets. In hopes of improving manmade mine-hunting sonar systems, two instrumentation packages were developed to monitor free-swimming dolphin motion and echolocation during open-water target detection tasks. The biosonar measurement tool (BMT) is carried by a dolphin and monitors underwater position and attitude while simultaneously recording echolocation clicks and returning echoes through high-gain binaural receivers. The instrumented mine simulator (IMS) is a modified bottom target that monitors echolocation signals arriving at the target during ensonification. Dolphin subjects were trained to carry the BMT in open-bay bottom-object target searches in which the IMS could serve as a bottom object. The instrumentation provides detailed data that reveal hereto-unavailable information on the search strategies of free-swimming dolphins conducting open-water, bottom-object search tasks with echolocation.

Instrumenting free-swimming dolphins echolocating in open water

NASA Astrophysics Data System (ADS)

Martin, Stephen W.; Phillips, Michael; Bauer, Eric J.; Moore, Patrick W.; Houser, Dorian S.

2005-04-01

Dolphins within the Navy Marine Mammal Program use echolocation to effectively locate underwater mines. They currently outperform manmade systems at similar tasks, particularly in cluttered environments and on buried targets. In hopes of improving manmade mine-hunting sonar systems, two instrumentation packages were developed to monitor free-swimming dolphin motion and echolocation during open-water target detection tasks. The biosonar measurement tool (BMT) is carried by a dolphin and monitors underwater position and attitude while simultaneously recording echolocation clicks and returning echoes through high-gain binaural receivers. The instrumented mine simulator (IMS) is a modified bottom target that monitors echolocation signals arriving at the target during ensonification. Dolphin subjects were trained to carry the BMT in open-bay bottom-object target searches in which the IMS could serve as a bottom object. The instrumentation provides detailed data that reveal hereto-unavailable information on the search strategies of free-swimming dolphins conducting open-water, bottom-object search tasks with echolocation. .

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.

A Biological Hierarchical Model Based Underwater Moving Object Detection

PubMed Central

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. PMID:25140194

Emerging From Water: Underwater Image Color Correction Based on Weakly Supervised Color Transfer

NASA Astrophysics Data System (ADS)

Li, Chongyi; Guo, Jichang; Guo, Chunle

2018-03-01

Underwater vision suffers from severe effects due to selective attenuation and scattering when light propagates through water. Such degradation not only affects the quality of underwater images but limits the ability of vision tasks. Different from existing methods which either ignore the wavelength dependency of the attenuation or assume a specific spectral profile, we tackle color distortion problem of underwater image from a new view. In this letter, we propose a weakly supervised color transfer method to correct color distortion, which relaxes the need of paired underwater images for training and allows for the underwater images unknown where were taken. Inspired by Cycle-Consistent Adversarial Networks, we design a multi-term loss function including adversarial loss, cycle consistency loss, and SSIM (Structural Similarity Index Measure) loss, which allows the content and structure of the corrected result the same as the input, but the color as if the image was taken without the water. Experiments on underwater images captured under diverse scenes show that our method produces visually pleasing results, even outperforms the art-of-the-state methods. Besides, our method can improve the performance of vision tasks.

Does underwater flash photography affect the behaviour, movement and site persistence of seahorses?

PubMed

Harasti, D; Gladstone, W

2013-11-01

The effect of flash photography on seahorse species has never been tested. An experiment was established to test the effect of flash photography and the handling of Hippocampus whitei, a medium-sized seahorse species endemic to Australia, on their behavioural responses, movements and site persistence. A total of 24 H. whitei were utilized in the experiment with eight in each of the three treatments (flash photography, handling and control). The effect of underwater flash photography on H. whitei movements was not significant; however, the effect of handling H. whitei to take a photograph had a significant effect on their short-term behavioural responses to the photographer. Kaplan-Meier log-rank test revealed that there was no significant difference in site persistence of H. whitei from each of the three treatments and that flash photography had no long-term effects on their site persistence. It is concluded that the use of flash photography by divers is a safe and viable technique with H. whitei, particularly if photographs can be used for individual identification purposes. © 2013 The Fisheries Society of the British Isles.

Design and Fabrication of Soft Morphing Ray Propulsor: Undulator and Oscillator.

PubMed

Kim, Hyung-Soo; Lee, Jang-Yeob; Chu, Won-Shik; Ahn, Sung-Hoon

2017-03-01

A soft morphing ray propulsor capable of generating an undulating motion in its pectoral fins was designed and fabricated. The propulsor used shape memory alloy for actuation, and the body was made with soft polymers. To determine the effects of undulation in the fins, two models that differed in terms of the presence of undulation were fabricated using different polymer materials. The experimental models were tested with a dynamometer to measure and compare thrust tendencies. Thrust measurements were conducted with various fin beat frequencies. Using the experimental data, the concept of an optimized standalone version of the ray robot was suggested and its prototype was fabricated. The fabricated robot was able to swim as fast as 0.26 body length per second and 38% more efficient than other smart material-based ray-like underwater robots.

Underwater methods for study of salmonids in the Intermountain West

Treesearch

Russell F. Thurow

1994-01-01

This guide describes underwater methods using snorkeling gear to study fish populations in flowing waters of the Intermountain West. It outlines procedures for estimating salmonid abundance and habitat use and provides criteria for identifying and estimating the size of fish underwater.

Deep Lake Explorer: Using citizen science to analyze underwater video from the Great Lakes

EPA Science Inventory

While underwater video collection technology continues to improve, advancements in underwater video analysis techniques have lagged. Crowdsourcing image interpretation using the Zooniverse platform has proven successful for many projects, but few projects to date have included vi...

Apparatus for Changing the Attack Angle of a Cavitator on a Supercavatating Underwater Research Model

DTIC Science & Technology

2005-07-18

the Invention 14 The present invention generally relates to an apparatus 15 for changing the attack of a cavitator on a supercavitating 16 underwater...research model. 17 2. Description of the Prior Art 18 Supercavitating underwater vehicles and projectiles are 19 known in the art. One such... supercavitating underwater 20 projectile is described in Harkins et al., U.S. Patent No. 21 5,955,698. This projectile uses a supercavitating nose 22 section that

Underwater Flow Visualization Methods in the Upper Layer of the Ocean.

DTIC Science & Technology

1981-05-22

AD-A107 919 NAVAL RESEARCH LAB WASHINGTON DC F/G 8/3 UNDERWATER FLOW VISUALIZATION METHODS IN T1E UPPER LAYER OF THE-ETC(U) AMAY 81 J R MCGRATH, C M...S.bOti1.) S. TYPE OF REPORT I PERIOD COVERED UNDERWATER FLOW VISUALIZATION METHODS Interim report on a continuingNRL problem. IN THE UPPER LAYER OF THE...56 UNDERWATER FLOW VISUALIZATION METHODS IN THE UPPER LAYER OF THE OCEAN 1. INTRODUCTION a) Purpose This report documents the

Optimal Estimation of Glider’s Underwater Trajectory with Depth-Dependent Correction Using the Navy Coastal Ocean Model with Application to Antisubmarine Warfare

DTIC Science & Technology

2014-09-01

deployed simultaneously. For example, a fleet of gliders would be able to act as an intelligence network by gathering underwater target information ...and to verify our novel method, a glider’s real underwater trajectory information must be obtained by using additional sensors like ADCP or DVL (see...lacks of inexpensive and efficient localization sensors during its subsurface mission. Therefore, knowing its precise underwater position is a

Cardiorespiratory performance of coronary artery disease patients on land versus underwater treadmill tests: a comparative study

PubMed Central

Garcia, Mauricio Koprowski; Rizzo, Limanara; Yazbek-Júnior, Paulo; Yutiyama, Daniela; da Silva, Fabiola Jomar; Matheus, Denise; Mastrocolla, Luiz Eduardo; Massad, Eduardo

2017-01-01

OBJECTIVE: To compare responses to a cardiopulmonary exercise test on land versus on an underwater treadmill, to assess the cardiorespiratory performance of coronary artery disease patients while immersed in warm water and to compare with the performance of healthy individuals. METHODS: The sample population consisted of 40 subjects, which included 20 coronary artery disease patients aged 63.7±8.89 years old, functional class I and II, according to the New York Hearth Association, and 20 healthy subjects aged 64.7±7.09 years old. The statistical significances were calculated through an ANOVA test with a (1 - β) power of 0.861. ClinicalTrials.gov: NCT00989248 (22). RESULTS: Significant differences were uncovered in coronary artery disease group regarding the variables heart beats (HB), (p>0.01), oxygen consumption (VO2), (p>0.01) and carbon dioxide production (VCO2) (p<0.01). Also, for the same group, in relation to the environment, water versus on land for HB, VO2, VCO2 and oxygen for each heart beat (VO2/HB) all of than (p<0.01). The stages for data collected featured the subject’s performance throughout the experiment, and within the given context, variables rating of perceived exertion (RPE), HB, VO2, VCO2 and VO2/HB (p<0.01) showed significant interactions between test stages and environment. Additionally, there was a significant interaction between the etiology and the test stages for the variables HB, VO2 and VCO2 (p<0.01). Electrocardiographic changes compatible with myocardial ischemia or arrhythmia were not observed. The subjects exhibited lower scores on Borg’s perceived exertion scale in the water than at every one of the test stages on land (p<0.01). CONCLUSION: This study show that a cardiopulmonary exercise test can be safely conducted in subjects in immersion and that the procedures, resources and equipment used yielded replicable and reliable data. Significant differences observed in water versus on land allow us to conclude that coronary artery disease patients are able to do physical exercise in water and that the physiological effects of immersion do not present any risk for such patients, as exercise was well tolerated by all subjects. PMID:29236912

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.

Sensor Network Architectures for Monitoring Underwater Pipelines

PubMed Central

Mohamed, Nader; Jawhar, Imad; Al-Jaroodi, Jameela; Zhang, Liren

2011-01-01

This paper develops and compares different sensor network architecture designs that can be used for monitoring underwater pipeline infrastructures. These architectures are underwater wired sensor networks, underwater acoustic wireless sensor networks, RF (Radio Frequency) wireless sensor networks, integrated wired/acoustic wireless sensor networks, and integrated wired/RF wireless sensor networks. The paper also discusses the reliability challenges and enhancement approaches for these network architectures. The reliability evaluation, characteristics, advantages, and disadvantages among these architectures are discussed and compared. Three reliability factors are used for the discussion and comparison: the network connectivity, the continuity of power supply for the network, and the physical network security. In addition, the paper also develops and evaluates a hierarchical sensor network framework for underwater pipeline monitoring. PMID:22346669

Underwater image enhancement through depth estimation based on random forest

NASA Astrophysics Data System (ADS)

Tai, Shen-Chuan; Tsai, Ting-Chou; Huang, Jyun-Han

2017-11-01

Light absorption and scattering in underwater environments can result in low-contrast images with a distinct color cast. This paper proposes a systematic framework for the enhancement of underwater images. Light transmission is estimated using the random forest algorithm. RGB values, luminance, color difference, blurriness, and the dark channel are treated as features in training and estimation. Transmission is calculated using an ensemble machine learning algorithm to deal with a variety of conditions encountered in underwater environments. A color compensation and contrast enhancement algorithm based on depth information was also developed with the aim of improving the visual quality of underwater images. Experimental results demonstrate that the proposed scheme outperforms existing methods with regard to subjective visual quality as well as objective measurements.

Sensor network architectures for monitoring underwater pipelines.

PubMed

Mohamed, Nader; Jawhar, Imad; Al-Jaroodi, Jameela; Zhang, Liren

2011-01-01

This paper develops and compares different sensor network architecture designs that can be used for monitoring underwater pipeline infrastructures. These architectures are underwater wired sensor networks, underwater acoustic wireless sensor networks, RF (radio frequency) wireless sensor networks, integrated wired/acoustic wireless sensor networks, and integrated wired/RF wireless sensor networks. The paper also discusses the reliability challenges and enhancement approaches for these network architectures. The reliability evaluation, characteristics, advantages, and disadvantages among these architectures are discussed and compared. Three reliability factors are used for the discussion and comparison: the network connectivity, the continuity of power supply for the network, and the physical network security. In addition, the paper also develops and evaluates a hierarchical sensor network framework for underwater pipeline monitoring.

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…

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.

Underwater Sensor Nodes and Networks

PubMed Central

Lloret, Jaime

2013-01-01

Sensor technology has matured enough to be used in any type of environment. The appearance of new physical sensors has increased the range of environmental parameters for gathering data. Because of the huge amount of unexploited resources in the ocean environment, there is a need of new research in the field of sensors and sensor networks. This special issue is focused on collecting recent advances on underwater sensors and underwater sensor networks in order to measure, monitor, surveillance of and control of underwater environments. On the one hand, from the sensor node perspective, we will see works related with the deployment of physical sensors, development of sensor nodes and transceivers for sensor nodes, sensor measurement analysis and several issues such as layer 1 and 2 protocols for underwater communication and sensor localization and positioning systems. On the other hand, from the sensor network perspective, we will see several architectures and protocols for underwater environments and analysis concerning sensor network measurements. Both sides will provide us a complete view of last scientific advances in this research field. PMID:24013489

Underwater Sensor Network Redeployment Algorithm Based on Wolf Search

PubMed Central

Jiang, Peng; Feng, Yang; Wu, Feng

2016-01-01

This study addresses the optimization of node redeployment coverage in underwater wireless sensor networks. Given that nodes could easily become invalid under a poor environment and the large scale of underwater wireless sensor networks, an underwater sensor network redeployment algorithm was developed based on wolf search. This study is to apply the wolf search algorithm combined with crowded degree control in the deployment of underwater wireless sensor networks. The proposed algorithm uses nodes to ensure coverage of the events, and it avoids the prematurity of the nodes. The algorithm has good coverage effects. In addition, considering that obstacles exist in the underwater environment, nodes are prevented from being invalid by imitating the mechanism of avoiding predators. Thus, the energy consumption of the network is reduced. Comparative analysis shows that the algorithm is simple and effective in wireless sensor network deployment. Compared with the optimized artificial fish swarm algorithm, the proposed algorithm exhibits advantages in network coverage, energy conservation, and obstacle avoidance. PMID:27775659

Underwater Calibration of Dome Port Pressure Housings

NASA Astrophysics Data System (ADS)

Nocerino, E.; Menna, F.; Fassi, F.; Remondino, F.

2016-03-01

Underwater photogrammetry using consumer grade photographic equipment can be feasible for different applications, e.g. archaeology, biology, industrial inspections, etc. The use of a camera underwater can be very different from its terrestrial use due to the optical phenomena involved. The presence of the water and camera pressure housing in front of the camera act as additional optical elements. Spherical dome ports are difficult to manufacture and consequently expensive but at the same time they are the most useful for underwater photogrammetry as they keep the main geometric characteristics of the lens unchanged. Nevertheless, the manufacturing and alignment of dome port pressure housing components can be the source of unexpected changes of radial and decentring distortion, source of systematic errors that can influence the final 3D measurements. The paper provides a brief introduction of underwater optical phenomena involved in underwater photography, then presents the main differences between flat and dome ports to finally discuss the effect of manufacturing on 3D measurements in two case studies.

Optimal Deployment of Sensor Nodes Based on Performance Surface of Underwater Acoustic Communication

PubMed Central

Choi, Jee Woong

2017-01-01

The underwater acoustic sensor network (UWASN) is a system that exchanges data between numerous sensor nodes deployed in the sea. The UWASN uses an underwater acoustic communication technique to exchange data. Therefore, it is important to design a robust system that will function even in severely fluctuating underwater communication conditions, along with variations in the ocean environment. In this paper, a new algorithm to find the optimal deployment positions of underwater sensor nodes is proposed. The algorithm uses the communication performance surface, which is a map showing the underwater acoustic communication performance of a targeted area. A virtual force-particle swarm optimization algorithm is then used as an optimization technique to find the optimal deployment positions of the sensor nodes, using the performance surface information to estimate the communication radii of the sensor nodes in each generation. The algorithm is evaluated by comparing simulation results between two different seasons (summer and winter) for an area located off the eastern coast of Korea as the selected targeted area. PMID:29053569

Testing Momentum Enhancement of Ribbon Fin Based Propulsion Using a Robotic Model With an Adjustable Body

NASA Astrophysics Data System (ADS)

English, Ian; Curet, Oscar

2016-11-01

Lighthill and Blake's 1990 momentum enhancement theory suggests there is a multiplicative propulsive effect linked to the ratio of body and fin heights in Gymnotiform and Balistiform swimmers, which propel themselves using multi-rayed undulating fins while keeping their bodies mostly rigid. Proof of such a momentum enhancement could have a profound effect on unmanned underwater vehicle design and shed light on the evolutionary advantage to body-fin ratios found in nature, shown as optimal for momentum enhancement in Lighthill and Blake's theory. A robotic ribbon fin with twelve independent fin rays, elastic fin membrane, and a body of adjustable height was developed specifically to experimentally test momentum enhancement. Thrust tests for various body heights were conducted in a recirculating flow tank at different flow speeds and fin flapping frequencies. When comparing thrust at different body heights, flow speeds, and frequencies to a 'no-body' thrust test case at each frequency and flow speed, data indicate there is no momentum enhancement factor due to the presence of a body on top of an undulating fin. This suggests that if there is a benefit to a specific ratio between body and fin height, it is not due to momentum enhancement.

Advanced Undersea Warfare Systems

DTIC Science & Technology

2011-06-01

122 hours188 187 Rowinski, Lech . “Submersible propulsion and energy.” 18 Mar. 2002. underwater.pg.gda.pl. 23 Apr. 2011. <http...Rowinski, Lech . “Submersible propulsion and energy.” 18 Mar. 2002. underwater.pg.gda.pl. 23 Apr. 2011. <http://www.underwater.pg.gda.pl/publikacje

Development of underwater cutting system by abrasive water-jet

NASA Astrophysics Data System (ADS)

Demura, Kenji; Yamaguchi, Hitoshi

1993-09-01

The technology to cut objects in the ocean's depths with abrasive water jets was examined for possible application in view of the greater water depths and sophistication involved in work on the ocean floor today. A test model was developed to study this technology's safety and practicability. The test model was designed for use at great water depths and has functions and a configuration that are unlike equipment used on land. A continuous, stable supply of abrasive is a distinctive design feature. In land applications, there had been problems with plugged tubes and an uneven supply. For this reason, the abrasive was converted to slurry form, and a continuous pressurized tube pump system was adopted for supply to the nozzle head. Also, a hydraulic motor that does not employ oil or electric power was used to provide an underwater drive that is environment-friendly. The report outlines the technology's general design concept including its distinctive functions and its configuration for use at great depths, and the report provides great detail on the equipment.

Real-Time Seismic Data from the Bottom Sea

PubMed Central

Roset, Xavier; Trullols, Enric; Artero-Delgado, Carola; Prat, Joana; Massana, Immaculada; Carbonell, Montserrat; Barco de la Torre, Jaime; Toma, Daniel Mihai

2018-01-01

An anchored marine seismometer, acquiring real-time seismic data, has been built and tested. The system consists of an underwater seismometer, a surface buoy, and a mooring line that connects them. Inductive communication through the mooring line provides an inexpensive, reliable, and flexible solution. Prior to the deployment the dynamics of the system have been simulated numerically in order to find optimal materials, cables, buoys, and connections under critical marine conditions. The seismometer used is a high sensitivity triaxial broadband geophone able to measure low vibrational signals produced by the underwater seismic events. The power to operate the surface buoy is provided by solar panels. Additional batteries are needed for the underwater unit. In this paper we also present the first results and an earthquake detection of a prototype system that demonstrates the feasibility of this concept. The seismometer transmits continuous data at a rate of 1000 bps to a controller equipped with a radio link in the surface buoy. A GPS receiver on the surface buoy has been configured to perform accurate timestamps on the seismic data, which makes it possible to integrate the seismic data from these marine seismometers into the existing seismic network. PMID:29642479

How Doth the Little Crocodilian: Analyzing the Influence of Environmental Viscosity on Feeding Performance of Juvenile Alligator mississippiensis

PubMed Central

Kerfoot, James R.; Easter, Emily; Elsey, Ruth M.

2016-01-01

Wetland habitats are used as nursery sites for hatchling and juvenile alligators (Alligator mississippiensis), where they utilize prey from aquatic and terrestrial settings. However, little is known about how viscosity of the medium influences feeding performance. We hypothesized that timing and linear excursion feeding kinematic variables would be different for individuals feeding on prey above the water compared with the same individuals feeding underwater. Individuals were fed immobile fish prey and feeding events were recorded using a high speed video camera. Feeding performance was summarized by analyzing three feeding kinematic variables (maximum gape, maximum gape velocity, duration of feeding bout) and success of strike. Results of a series of paired t-tests indicated no significant difference in kinematic variables between feeding events above water compared with underwater. Similarity in feeding performance could indicate that prey-capture is not altered by environmental viscosity or that feeding behavior can mitigate its influence. Behavioral differences were observed during feeding events with alligators approaching underwater prey having their mouths partially opened versus fully closed when feeding above water. This behavior could be an indication of a strategy used to overcome water viscosity. PMID:27706023

Effect of Nozzle Geometry on Characteristics of Submerged Gas Jet and Bubble Noise.

PubMed

Bie, Hai-Yan; Ye, Jian-Jun; Hao, Zong-Rui

2016-10-01

Submerged exhaust noise is one of the main noise sources of underwater vehicles. The nozzle features of pipe discharging systems have a great influence on exhaust noise, especially on the noise produced by gas-liquid two-phase flow outside the nozzle. To study the influence of nozzle geometry on underwater jet noises, a theoretical study was performed on the critical weber number at which the jet flow field morphology changes. The underwater jet noise experiments of different nozzles under various working conditions were carried out. The experimental results implied that the critical weber number at which the jet flow transformed from bubbling regime to jetting regime was basically identical with the theoretical analysis. In the condition of jetting regime, the generated cavity of elliptical and triangular nozzles was smaller than that of the circular nozzle, and the middle- and high-frequency bands increased nonlinearly. The radiated noise decreased with the decrease in nozzle diameter. Combined with theoretical analysis and experimental research, three different submerged exhaust noise reduction devices were designed, and the validation tests proved that the noise reduction device with folds and diversion cone was the most effective. © 2015 Society for Laboratory Automation and Screening.

DUMAND-II (deep underwater muon and neutrino detector) progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, K.K.; The DUMAND Collaboration

1995-07-10

The DUMAND II detector will search for astronomical sources of high energy neutrinos. Successful deployment of the basic infrastructure, including the shore cable, the underwater junction box, and an environmental module was accomplished in December, 1993. One optical module string was also deployed and operated, logging data for about 10 hours. The underwater cable was connected to the shore station where we were able to successfully exercise system controls and log further environmental data. After this time, water leaking into the electronics control module for the deployed string disabled the string electrical system. The acquired data are consistent with themore » expected rate of downgoing muons, and our ability to reconstruct muons was demonstrated. The measured acoustical backgrounds are consistent with expectation, which should allow acoustical detection of nearby PeV particle cascades. The disabled string has been recovered and is undergoing repairs ashore. We have identified the source of the water leak and implemented additional testing and QC procedures to ensure no repetition in our next deployment. We will be ready to deploy three strings and begin continuous data taking in late 1994 or early 1995. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less

Real-Time Seismic Data from the Bottom Sea.

PubMed

Roset, Xavier; Trullols, Enric; Artero-Delgado, Carola; Prat, Joana; Del Río, Joaquin; Massana, Immaculada; Carbonell, Montserrat; Barco de la Torre, Jaime; Toma, Daniel Mihai

2018-04-08

An anchored marine seismometer, acquiring real-time seismic data, has been built and tested. The system consists of an underwater seismometer, a surface buoy, and a mooring line that connects them. Inductive communication through the mooring line provides an inexpensive, reliable, and flexible solution. Prior to the deployment the dynamics of the system have been simulated numerically in order to find optimal materials, cables, buoys, and connections under critical marine conditions. The seismometer used is a high sensitivity triaxial broadband geophone able to measure low vibrational signals produced by the underwater seismic events. The power to operate the surface buoy is provided by solar panels. Additional batteries are needed for the underwater unit. In this paper we also present the first results and an earthquake detection of a prototype system that demonstrates the feasibility of this concept. The seismometer transmits continuous data at a rate of 1000 bps to a controller equipped with a radio link in the surface buoy. A GPS receiver on the surface buoy has been configured to perform accurate timestamps on the seismic data, which makes it possible to integrate the seismic data from these marine seismometers into the existing seismic network.

Adhesion beyond the interface: Molecular adaptations of the mussel byssus to the intertidal zone

NASA Astrophysics Data System (ADS)

MIller, Dusty Rose

The California mussel, Mytilus californianus, adheres robustly in the high-energy and oxidizing intertidal zone with a fibrous holdfast called the byssus using 3,4-dihydroxyphenyl-L-alanine (Dopa)-containing adhesive mussel foot proteins (mfps). There are many supporting roles to mussel adhesion that are intimately linked and ultimately responsible for mussel byssus's durable and dynamic adhesion. This dissertation explores these supporting mechanisms, including delivery of materials underwater, iron binding, friction, and antioxidant activity. As the outermost covering of the byssus, the cuticle deserves particular attention for its supporting roles to adhesion including the high stiffness and extensibility of the M. californianus byssal cuticle, which make it one of the most energy tolerant materials known. The cuticle's matrix-granule composite structure contributes to its toughness by microcracking between its harder granules and softer matrix. We investigated delivery of cuticular material underwater, cohesion of cuticle proteins, and surface damage mitigation by cuticle protein-based coacervates. To investigate underwater material delivery, we made cuticle matrix mimics by coacervating a key cuticular protein, Mytilus californianus foot protein 1, mfp-1, with hyaluronic acid. These matrix mimics coacervated over a wide range of solution conditions, delivered concentrated material, settled on and coated surfaces underwater. Because the granules are composed of mfp-1 condensed with iron, we used the surface forces apparatus to investigate the effects of iron on the cohesion of mfp-1 from two different species of mussels and found that subtle sequence variations modulate cohesion. Using the coacervate matrix mimics and, modeling the granules as a hard surface (mica), we investigated the wear protection of coacervated mfp-1/HA to mica under frictional shear and found that preventing wear depends critically on the presence of Dopa groups. In addition to cuticle-derived mechanisms for adhesion protection, we also tested for direct chemical mechanisms by tracking redox in the mussel adhesive plaques and found a persistent reservoir of antioxidant activity that can protect Dopa from oxidation. Overall, the mussel byssus represents an excellent model system for understanding adaptive mechanisms of both underwater adhesives and tough materials and I propose in this dissertation that these supporting mechanisms are intimately linked and ultimately responsible for the durable and dynamic underwater adhesion of mussels in the intertidal zone.

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…

46 CFR 115.650 - Alternative Hull Examination (AHE) Program options: Divers or underwater ROV.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Alternative Hull Examination (AHE) Program options... MORE THAN 49 PASSENGERS INSPECTION AND CERTIFICATION Hull and Tailshaft Examinations § 115.650 Alternative Hull Examination (AHE) Program options: Divers or underwater ROV. To complete your underwater...

Visual resource management of the sea

Treesearch

Louis V. Mills Jr.

1979-01-01

The scenic quality of the marine environment has become an important concern for the design and planning professions. Increased public use of the underwater environment has resulted from technological advancements in SCUBA, recreational submarines and through development of under-water restaurants and parks. This paper presents an approach to an underwater visual...

Seeking Teachers for Underwater Robotics PD Program

ERIC Educational Resources Information Center

McGrath, Beth; Sayres, Jason

2012-01-01

With funding from the National Science Foundation (NSF), ITEEA members will contribute to the development of a hybrid professional development program designed to facilitate the scale-up of an innovative underwater robotics curriculum. WaterBotics[TM] is an underwater robotics curriculum that targets students in middle and high school classrooms…

77 FR 12355 - Hours of Service of Drivers: Underwater Construction Corporation Application for Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-29

...-0376] Hours of Service of Drivers: Underwater Construction Corporation Application for Exemption AGENCY...; request for comments. SUMMARY: FMCSA has received an application from the Underwater Construction... duty status for each 24 hour period using methods prescribed in that section. UCC claims that...

AUV Underwater Positioning Algorithm Based on Interactive Assistance of SINS and LBL.

PubMed

Zhang, Tao; Chen, Liping; Li, Yao

2015-12-30

This paper studies an underwater positioning algorithm based on the interactive assistance of a strapdown inertial navigation system (SINS) and LBL, and this algorithm mainly includes an optimal correlation algorithm with aided tracking of an SINS/Doppler velocity log (DVL)/magnetic compass pilot (MCP), a three-dimensional TDOA positioning algorithm of Taylor series expansion and a multi-sensor information fusion algorithm. The final simulation results show that compared to traditional underwater positioning algorithms, this scheme can not only directly correct accumulative errors caused by a dead reckoning algorithm, but also solves the problem of ambiguous correlation peaks caused by multipath transmission of underwater acoustic signals. The proposed method can calibrate the accumulative error of the AUV position more directly and effectively, which prolongs the underwater operating duration of the AUV.

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).

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

Underwater disaster victim identification: the process and the problems.

PubMed

Winskog, Calle

2012-06-01

An underwater disaster may involve a crime scene investigation which should be handled as if it were located above water and include a detailed description and documentation of items, belongings and findings. The environment, however, creates special circumstances, each with specific problems that are not encountered during land investigations. Risks associated with underwater recovery cannot be overestimated and underwater disaster recovery diving should not be performed without special training and careful pre-dive planning. Handling of cadavers in an underwater recovery operation also requires special training and a systematic approach to victim recovery. Environmental circumstances, local judicial requirements, religious and cultural issues and the scope of the disaster are only some of the factors that have to be considered before commencing any aquatic disaster victim recovery operation.

[The heart and underwater diving].

PubMed

Lafay, V

2006-11-01

Cardiovascular examination of a certain number of candidates for underwater diving raises justifiable questions of aptitude. An indicative list of contraindications has been proposed by the French Federation of Underwater Studies and Sports but a physiopathological basis gives a better understanding of what is involved. During diving, the haemodynamic changes due not only to the exercise but also to cold immersion, hyperoxaemia and decompression impose the absence of any symptomatic cardiac disease. Moreover, the vasoconstriction caused by the cold and hyperoxaemia should incite great caution in both coronary and hypertensive patients. The contraindication related to betablocker therapy is controversial and the debate has not been settled in France. The danger of drowning makes underwater diving hazardous in all pathologies carrying a risk of syncope. Pacemaker patients should be carefully assessed and the depth of diving limited. Finally, the presence of right-to-left intracardiac shunts increases the risk of complications during decompressionand contraindicates underwater diving. Patent foramen ovale is a special case but no special investigation is required for its detection. The cardiologist examining candidates for underwater diving should take all these factors into consideration because, although underwater diving is a sport associated with an increased risk, each year there are more and more people, with differing degrees of aptitude, who wish to practice it.

Affordable underwater wireless optical communication using LEDs

NASA Astrophysics Data System (ADS)

Pilipenko, Vladimir; Arnon, Shlomi

2013-09-01

In recent years the need for high data rate underwater wireless communication (WC) has increased. Nowadays, the conventional technology for underwater communication is acoustic. However, the maximum data rate that acoustic technology can provide is a few kilobits per second. On the other hand, emerging applications such as underwater imaging, networks of sensors and swarms of underwater vehicles require much faster data rates. As a result, underwater optical WC, which can provide much higher data rates, has been proposed as an alternative means of communication. In addition to high data rates, affordable communication systems become an important feature in the development requirements. The outcome of these requirements is a new system design based on off-the-shelf components such as blue and green light emitting diodes (LEDs). This is due to the fact that LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness. However, there are some challenges to be met when incorporating LEDs as part of the optical transmitter, such as low modulation rates and non linearity. In this paper, we review the main challenges facing the incorporation of LEDs as an integral part of underwater WC systems and propose some techniques to mitigate the LED limitations in order to achieve high data rate communication

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

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.