Injury rate in a helicopter underwater escape trainer (HUET) from 2005-2012.

PubMed

Brooks, Christopher J; MacDonald, Conor V; Gibbs, Peter N A

2014-08-01

Helicopter underwater escape training (HUET) carries a potential for injury and this paper identifies the injury rate. A marine survival training school registry of all students trained between 2005-2012 in HUET and the coinciding accident records were examined. There were 8902 students trained in a helicopter underwater escape simulator for a total of 59,245 underwater escapes. There were 40 cases where only first-aid was required and 3 serious injuries (a laceration requiring 5 sutures, 1 dislocated shoulder, and 1 water aspiration requiring hospitalization). There were no deaths and no problems reported with using the Emergency Breathing System (EBS) or Air Pocket. Of the injuries, 11 were due to the student using a poor escape technique. The overall probability of injury was 0.74 per 1000 ascents. In HUET training, there is a very low injury rate with almost no significant severity. Although not scientifically proven, this would suggest that the low incident rate is due to good medical screening and the attention given by instructors to anxious students. Compared to other training such as diving, parachute jumping, and submarine escape training, the rate of injury was considerably lower.

Underwater, low-frequency noise in a coastal sea turtle habitat.

PubMed

Samuel, Y; Morreale, S J; Clark, C W; Greene, C H; Richmond, M E

2005-03-01

Underwater sound was recorded in one of the major coastal foraging areas for juvenile sea turtles in the Peconic Bay Estuary system in Long Island, New York. The recording season of the underwater environment coincided with the sea turtle activity season in an inshore area where there is considerable boating and recreational activity, especially during the summer between Independence Day and Labor Day. Within the range of sea turtle hearing, average noise pressure reached 110 dB during periods of high human activity and diminished proportionally, down to 80 dB, with decreasing human presence. Therefore, during much of the season when sea turtles are actively foraging in New York waters, their coastal habitats are flooded with underwater noise. During the period of highest human activity, average noise pressures within the range of frequencies heard by sea turtles were greater by over two orders of magnitude (26 dB) than during the lowest period of human activity. Sea turtles undoubtedly are exposed to high levels of noise, most of which is anthropogenic. Results suggest that continued exposure to existing high levels of pervasive anthropogenic noise in vital sea turtle habitats and any increase in noise could affect sea turtle behavior and ecology.

Secured Optical Communications Using Quantum Entangled Two-Photon Transparency Modulation

NASA Technical Reports Server (NTRS)

Nguyen, Quang-Viet (Inventor); Kojima, Jun (Inventor); Lekki, John (Inventor)

2015-01-01

A system and method is disclosed wherein optical signals are coded in a transmitter by tuning or modulating the interbeam delay time (which modulates the fourth-order coherence) between pairs of entangled photons. The photon pairs are either absorbed or not absorbed (transparent) by an atomic or molecular fluorescer in a receiver, depending on the inter-beam delay that is introduced in the entangled photon pairs. Upon the absorption, corresponding fluorescent optical emissions follow at a certain wavelength, which are then detected by a photon detector. The advantage of the disclosed system is that it eliminates a need of a coincidence counter to realize the entanglement-based secure optical communications because the absorber acts as a coincidence counter for entangled photon pairs.

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

NASA Astrophysics Data System (ADS)

Ramesh, Sai Sudha; Lim, Kian Meng

2017-03-01

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

Boron-Coated Straw Collar for Uranium Neutron Coincidence Collar Replacement

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

Hu, Jianwei; Croft, Stephen; McElroy, Robert Dennis

The objective of this project was to design and optimize, in simulation space, an active neutron coincidence counter (or collar) using boron-coated straws (BCSs) as a non- 3He replacement to the Uranium Neutron Coincidence Collar (UNCL). UNCL has been used by the International Atomic Energy Agency (IAEA) and European Atomic Energy Community (Euratom) since the 1980s to verify the 235U content in fresh light water reactor fuel assemblies for safeguards purposes. This report documents the design and optimization of the BCS collar.

An alpha–gamma coincidence spectrometer based on the Photon–Electron Rejecting Alpha Liquid Scintillation (PERALS®) system

DOE PAGES

Cadieux, J. R.; Fugate, G. A.; King, III, G. S.

2015-02-07

Here, an alpha–gamma coincidence spectrometer has been developed for the measurement of selected actinide isotopes in the presence of high beta/gamma fields. The system is based on a PERALS® liquid scintillation counter for beta/alpha discrimination and was successfully tested with both high purity germanium and bismuth germanate, gamma-ray detectors using conventional analog electronics.

Portable multiplicity counter

DOEpatents

Newell, Matthew R [Los Alamos, NM; Jones, David Carl [Los Alamos, NM

2009-09-01

A portable multiplicity counter has signal input circuitry, processing circuitry and a user/computer interface disposed in a housing. The processing circuitry, which can comprise a microcontroller integrated circuit operably coupled to shift register circuitry implemented in a field programmable gate array, is configured to be operable via the user/computer interface to count input signal pluses receivable at said signal input circuitry and record time correlations thereof in a total counting mode, coincidence counting mode and/or a multiplicity counting mode. The user/computer interface can be for example an LCD display/keypad and/or a USB interface. The counter can include a battery pack for powering the counter and low/high voltage power supplies for biasing external detectors so that the counter can be configured as a hand-held device for counting neutron events.

A Study of Underwater Sound Ray Tracing Methodology

DTIC Science & Technology

1990-09-01

SRER ,LB,SV,SVU2,SVU,SU2,SU4,GI,G PIE = 3.14159265359D0 77 lEST = 0 MI = M C DISTRIBUTE THE K SOURCES EQUALLY AROUND THE CIRCLE COUNTER C CLOCKWISE...C(I) - TI-R(I TIMER(I = TIMCO) - T(5) HER(IW HC(I - Hl ZER(IW ZC(I - ZI SR = DSQRT(HI**2 + WA - Zl)**2) SRER = DSQRT(HC(I)**2 + (A2 - Zl)**2) - SR 50

Enhancing acoustic signal response and absorption of an underwater coated plate by embedding periodical inhomogeneities.

PubMed

Zhang, Yanni; Pan, Jie

2017-12-01

An underwater structure is proposed for simultaneous detection and stealth purposes by embedding periodic signal conditioning plates (SCPs) at the interface of two elastic coatings attached to an elastic plate. Results show that the embedded SCPs can enhance sound absorption at frequencies below the coincidence frequency of the plate (f c ). Significantly enhanced absorption occurs at five peaks, of which the peak due to excited localized bending resonance in the outer coating between SCPs is the most significant. When the dilatational velocity of the outer coating equals that of the inner coating, nearly total absorption occurs in a wideband, owing to strong coupling between the localized waveguide resonance in the outer coating and that in the inner coating, and the diffraction waves by the SCPs. Meanwhile, an amplified acoustic signal of over 14 dB is observed at most frequencies within 0 ∼ f c at the coatings' interface close to the SCPs' edges, owing to focused stress formed there. Peaks in the signal response at maximal 30 dB are also observed. These peak frequencies are coincident with or close to the peak frequencies of absorption, demonstrating that significantly enhanced acoustic signal and absorption can be achieved simultaneously through the use of embedded periodic SCPs.

Multianode cylindrical proportional counter for high count rates

DOEpatents

Hanson, J.A.; Kopp, M.K.

1980-05-23

A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (< 60 keV) at count rates of greater than 10/sup 5/ counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

Multianode cylindrical proportional counter for high count rates

DOEpatents

Hanson, James A.; Kopp, Manfred K.

1981-01-01

A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (<60 keV) at count rates of greater than 10.sup.5 counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

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.

Variations in AmLi source spectra and their estimation utilizing the 5 Ring Multiplicity Counter

DOE PAGES

Weinmann-Smith, Robert; Beddingfield, David H.; Enqvist, Andreas; ...

2017-02-28

Active-mode assay systems are widely used for the safeguards of uranium items to verify compliance with the Non-Proliferation Treaty. Systems such as the Active-Well Coincidence Counter (AWCC) and the Uranium Neutron Coincidence Collar (UNCL) use americium-lithium (AmLi) neutron sources to induce fissions which are measured to determine the sample mass. These systems have historically relied on calibrations derived from well-defined standards. Recently, restricted access to standards or more difficult measurements have resulted in a reliance on modeling and simulation for the calibration of systems, which introduces potential simulation biases. Furthermore, the AmLi source energy spectra commonly used in the safeguardsmore » community do not accurately represent measurement results and the spectrum uncertainty can represent a large contribution to the total modeling uncertainty in active-mode systems.« less

Monte Carlo simulation of β γ coincidence system using plastic scintillators in 4π geometry

NASA Astrophysics Data System (ADS)

Dias, M. S.; Piuvezam-Filho, H.; Baccarelli, A. M.; Takeda, M. N.; Koskinas, M. F.

2007-09-01

A modified version of a Monte Carlo code called Esquema, developed at the Nuclear Metrology Laboratory in IPEN, São Paulo, Brazil, has been applied for simulating a 4 πβ(PS)-γ coincidence system designed for primary radionuclide standardisation. This system consists of a plastic scintillator in 4 π geometry, for alpha or electron detection, coupled to a NaI(Tl) counter for gamma-ray detection. The response curves for monoenergetic electrons and photons have been calculated previously by Penelope code and applied as input data to code Esquema. The latter code simulates all the disintegration processes, from the precursor nucleus to the ground state of the daughter radionuclide. As a result, the curve between the observed disintegration rate as a function of the beta efficiency parameter can be simulated. A least-squares fit between the experimental activity values and the Monte Carlo calculation provided the actual radioactive source activity, without need of conventional extrapolation procedures. Application of this methodology to 60Co and 133Ba radioactive sources is presented and showed results in good agreement with a conventional proportional counter 4 πβ(PC)-γ coincidence system.

The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter

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

McElroy, Robert Dennis; Cleveland, Steven L.

The 235U mass assay of bulk uranium items, such as oxide canisters, fuel pellets, and fuel assemblies, is not achievable by traditional gamma-ray assay techniques due to the limited penetration of the item by the characteristic 235U gamma rays. Instead, fast neutron interrogation methods such as active neutron coincidence counting must be used. For international safeguards applications, the most commonly used active neutron systems, the Active Well Coincidence Counter (AWCC), Uranium Neutron Collar (UNCL) and 252Cf Shuffler, rely on fast neutron interrogation using an isotopic neutron source [i.e., 252Cf or Am(Li)] to achieve better measurement accuracies than are possible usingmore » gamma-ray techniques for high-mass, high-density items. However, the Am(Li) sources required for the AWCC and UNCL systems are no longer manufactured, and newly produced systems rely on limited supplies of sources salvaged from disused instruments. The 252Cf shuffler systems rely on the use of high-output 252Cf sources, which while still available have become extremely costly for use in routine operations and require replacement every five to seven years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. In this work, we made use of Oak Ridge National Laboratory’s (ORNL’s) Large Volume Active Well Coincidence Counter (LV-AWCC) and a commercially available deuterium-deuterium (D-D) neutron generator to examine the potential of the D-D neutron generator as an alternative to the isotopic sources. We present the performance of the LV-AWCC with D-D generator for the assay of 235U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium (DU), low enriched uranium (LEU), and highly enriched uranium (HEU) items.« less

Comparison Of 252Cf Time Correlated Induced Fisssion With AmLi Induced Fission On Fresh MTR Research Reactor Fuel

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

Joshi, Jay Prakash

The effective application of international safeguards to research reactors requires verification of spent fuel as well as fresh fuel. To accomplish this goal various nondestructive and destructive assay techniques have been developed in the US and around the world. The Advanced Experimental Fuel Counter (AEFC) is a nondestructive assay (NDA) system developed at Los Alamos National Laboratory (LANL) combining both neutron and gamma measurement capabilities. Since spent fuel assemblies are stored in water, the system was designed to be watertight to facilitate underwater measurements by inspectors. The AEFC is comprised of six 3He detectors as well as a shielded andmore » collimated ion chamber. The 3He detectors are used for active and passive neutron coincidence counting while the ion chamber is used for gross gamma counting. Active coincidence measurement data is used to measure residual fissile mass, whereas the passive coincidence measurement data along with passive gamma measurement can provide information about burnup, cooling time, and initial enrichment. In the past, most of the active interrogation systems along with the AEFC used an AmLi neutron interrogation source. Owing to the difficulty in obtaining an AmLi source, a 252Cf spontaneous fission (SF) source was used during a 2014 field trail in Uzbekistan as an alternative. In this study, experiments were performed to calibrate the AEFC instrument and compare use of the 252Cf spontaneous fission source and the AmLi (α,n) neutron emission source. The 252Cf source spontaneously emits bursts of time-correlated prompt fission neutrons that thermalize in the water and induce fission in the fuel assembly. The induced fission (IF) neutrons are also time correlated resulting in more correlated neutron detections inside the 3He detector, which helps reduce the statistical errors in doubles when using the 252Cf interrogation source instead of the AmLi source. In this work, two MTR fuel assemblies varying both in size and number of fuel plates were measured using 252Cf and AmLi active interrogation sources. This paper analyzes time correlated induced fission (TCIF) from fresh MTR fuel assemblies due to 252Cf and AmLi active interrogation sources.« less

Self-regulating neutron coincidence counter

DOEpatents

Baron, N.

1980-06-16

A device for accurately measuring the mass of /sup 240/Pu and /sup 239/Pu in a sample having arbitrary moderation and mixed with various contaminants. The device utilizes a thermal neutron well counter which has two concentric rings of neutron detectors separated by a moderating material surrounding the well. Neutron spectroscopic information derived by the two rings of detectors is used to measure the quantity of /sup 239/Pu and /sup 240/Pu in device which corrects for background radiation, deadtime losses of the detector and electronics and various other constants of the system.

Xe isotope detection and discrimination using beta spectroscopy with coincident gamma spectroscopy

NASA Astrophysics Data System (ADS)

Reeder, P. L.; Bowyer, T. W.

1998-02-01

Beta spectroscopic techniques show promise of significant improvements for a beta-gamma coincidence counter that is part of a system for analyzing Xe automatically separated from air. The previously developed counting system for 131mXe, 133mXe, 133gXe, and 135gXe can be enhanced to give additional discrimination between these Xe isotopes by using the plastic scintillation sample cell as a beta spectrometer to resolve the conversion electron peaks. The automated system will be a key factor in monitoring the Comprehensive Test Ban Treaty.

Four methods for determining the composition of trace radioactive surface contamination of low-radioactivity metal

NASA Astrophysics Data System (ADS)

O'Keeffe, H. M.; Burritt, T. H.; Cleveland, B. T.; Doucas, G.; Gagnon, N.; Jelley, N. A.; Kraus, C.; Lawson, I. T.; Majerus, S.; McGee, S. R.; Myers, A. W.; Poon, A. W. P.; Rielage, K.; Robertson, R. G. H.; Rosten, R. C.; Stonehill, L. C.; VanDevender, B. A.; Van Wechel, T. D.

2011-12-01

Four methods for determining the composition of low-level uranium- and thorium-chain surface contamination are presented. One method is the observation of Cherenkov light production in water. In two additional methods a position-sensitive proportional counter surrounding the surface is used to make both a measurement of the energy spectrum of alpha particle emissions and also coincidence measurements to derive the thorium-chain content based on the presence of short-lived isotopes in that decay chain. The fourth method is a radiochemical technique in which the surface is eluted with a weak acid, the eluate is concentrated, added to liquid scintillator and assayed by recording beta-alpha coincidences. These methods were used to characterize two 'hotspots' on the outer surface of one of the 3He proportional counters in the Neutral Current Detection array of the Sudbury Neutrino Observatory experiment. The methods have similar sensitivities, of order tens of ng, to both thorium- and uranium-chain contamination.

Design of the biosonar simulator for dolphin's clicks waveform reproduction

NASA Astrophysics Data System (ADS)

Ishii, Ken; Akamatsu, Tomonari; Hatakeyama, Yoshimi

1992-03-01

The emitted clicks of Dall's porpoises consist of a pulse train of burst signals with an ultrasonic carrier frequency. The authors have designed a biosonar simulator to reproduce the waveforms associated with a dolphin's clicks underwater. The total reproduction system consists of a click signal acquisition block, a waveform analysis block, a memory unit, a click simulator, and a underwater, ultrasonic wave transmitter. In operation, data stored in an EPROM (Erasable Programmable Read Only Memory) are read out sequentially by a fast clock and converted to analog output signals. Then an ultrasonic power amplifier reproduces these signals through a transmitter. The click signal replaying block is referred to as the BSS (Biosonar Simulator). This is what simulates the clicks. The details of the BSS are described in this report. A unit waveform is defined. The waveform is divided into a burst period and a waiting period. Clicks are a sequence based on a unit waveform, and digital data are sequentially read out from an EPROM of waveform data. The basic parameters of the BSS are as follows: (1) reading clock, 100 ns to 25.4 microseconds; (2) number of reading clock, 34 to 1024 times; (3) counter clock in a waiting period, 100 ns to 25.4 microseconds; (4) number of counter clock, zero to 16,777,215 times; (5) number of burst/waiting repetition cycle, one to 128 times; and (6) transmission level adjustment by a programmable attenuator, zero to 86.5 dB. These basic functions enable the BSS to replay clicks of Dall's porpoise precisely.

Detection of Neutrons with Scintillation Counters

DOE R&D Accomplishments Database

Hofstadter, R.

1948-11-01

Detection of slow neutrons by: detection of single gamma rays following capture by cadmium or mercury; detection of more than one gamma ray by observing coincidences after capture; detection of heavy charged particles after capture in lithium or baron nuclei; possible use of anthracene for counting fast neutrons investigated briefly.

An automated LS(β)- NaI(Tl)(γ) coincidence system as absolute standard for radioactivity measurements.

PubMed

Joseph, Leena; Das, A P; Ravindra, Anuradha; Kulkarni, D B; Kulkarni, M S

2018-07-01

4πβ-γ coincidence method is a powerful and widely used method to determine the absolute activity concentration of radioactive solutions. A new automated liquid scintillator based coincidence system has been designed, developed, tested and established as absolute standard for radioactivity measurements. The automation is achieved using PLC (programmable logic controller) and SCADA (supervisory control and data acquisition). Radioactive solution of 60 Co was standardized to compare the performance of the automated system with proportional counter based absolute standard maintained in the laboratory. The activity concentrations determined using these two systems were in very good agreement; the new automated system can be used for absolute measurement of activity concentration of radioactive solutions. Copyright © 2018. Published by Elsevier Ltd.

Multiple Input Sliding Mode Control for Autonomous Diving and Steering of Underwater Vehicles

DTIC Science & Technology

1990-12-01

States Navy B.S., University of Minnesota Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MECHANICAL...VARIABLES C REAL UCO,UC,VCO,VC REAL TARGET,PSID,DAWAY,ALPHA REAL XD,XD1,XD2,XPOS,XCURRXCTE,YD,YD1,YD2,YPOS,YCU RR,YCTE REAL XDOT,YDOT INTEGER IWAY, INAV C...INVERT THE MASS MATRIX USING IMSL LIBRARY SUBROUTINE CALL LINRG(3,MM,3,MMINV,3) C C INITIALIZE THE COUNTERS C ISCREEN=l INAV =0 IWAY=l IOUT=1 C C OPEN

Implementation of the TDCR liquid scintillation method at CNEA-LMR, Argentina.

PubMed

Arenillas, Pablo; Cassette, Philippe

2006-01-01

During the last two years, a triple-to-double coincidence ratio (TDCR) system was assembled and adjusted at the CNEA-LMR, Argentina. The new counting system will add complementary capabilities to the absolute measurements section of the CNEA-LMR. This work describes its implementation and validation. Several checks and a set of beta-emitting standard solutions were used in order to perform the validation experiments. In preliminary measurements, a 3H LNHB solution with reference activity concentration of (119.7+/-0.9) kBq/g on 11 November 2003 was used. The CNEA-LMR TDCR counter gave, at the same reference date, an activity concentration of (120+/-1) kBq/g. Results and improvements are presented in detail. Concerning the asymmetry of the system, the quantum efficiency of the three photomultiplier tubes was studied for different operating conditions of the focusing voltage. The counter also includes an automatic system to change the efficiency by defocusing the photomultipliers and on the other hand, it was coupled to a HPGe detector to also measure beta-gamma coincidences.

Micromachined fiber optic Fabry-Perot underwater acoustic probe

NASA Astrophysics Data System (ADS)

Wang, Fuyin; Shao, Zhengzheng; Hu, Zhengliang; Luo, Hong; Xie, Jiehui; Hu, Yongming

2014-08-01

One of the most important branches in the development trend of the traditional fiber optic physical sensor is the miniaturization of sensor structure. Miniature fiber optic sensor can realize point measurement, and then to develop sensor networks to achieve quasi-distributed or distributed sensing as well as line measurement to area monitoring, which will greatly extend the application area of fiber optic sensors. The development of MEMS technology brings a light path to address the problems brought by the procedure of sensor miniaturization. Sensors manufactured by MEMS technology possess the advantages of small volume, light weight, easy fabricated and low cost. In this paper, a fiber optic extrinsic Fabry-Perot interferometric underwater acoustic probe utilizing micromachined diaphragm collaborated with fiber optic technology and MEMS technology has been designed and implemented to actualize underwater acoustic sensing. Diaphragm with central embossment, where the embossment is used to anti-hydrostatic pressure which would largely deflect the diaphragm that induce interferometric fringe fading, has been made by double-sided etching of silicon on insulator. By bonding the acoustic-sensitive diaphragm as well as a cleaved fiber end in ferrule with an outer sleeve, an extrinsic Fabry-Perot interferometer has been constructed. The sensor has been interrogated by quadrature-point control method and tested in field-stable acoustic standing wave tube. Results have been shown that the recovered signal detected by the sensor coincided well with the corresponding transmitted signal and the sensitivity response was flat in frequency range from 10 Hz to 2kHz with the value about -154.6 dB re. 1/μPa. It has been manifest that the designed sensor could be used as an underwater acoustic probe.

Underwater sky image as remote sensing instrument of sea roughness parameters and its variability

NASA Astrophysics Data System (ADS)

Molkov, Alexander A.; Dolin, Lev S.; Kapustin, Ivan A.; Sergievskaya, Irina A.; Shomina, Olga V.

2016-10-01

At present a sufficient amount of methods is offered for determining the characteristics of sea roughness in accordance with optical images of wavy water surface obtained from different near-shore constructions, sea platforms, vessels, aircraft and satellites. The most informative elements in this case are solar path and peripheral areas of the image free from sun glitters. However, underwater images of the surface obtained with the help of optical receiver located at a certain depth contain apart from the mentioned elements one more informative element- Snell's window. It is an underwater sky image which distortions of border contain information on roughness characteristics and serve as the indicator of its variability. The research offers the method for determining energy spectra of wind waves in accordance with the second statistical moment of Snell's window image. The results of testing of the offered method are provided based on natural images registered in the course of trip to the Black Sea under conditions of different wind and wave environment for clear surface and surface covered by surfactant films. For both cases frequency spectra of surface slopes are recovered and their good coincidence to the spectra received by processing of signals from a string wave recorder is established. Efficiency of application of the offered method for tasks of remote monitoring and environmental control of natural reservoirs is shown.

Ring magnet firing angle control

DOEpatents

Knott, M.J.; Lewis, L.G.; Rabe, H.H.

1975-10-21

A device is provided for controlling the firing angles of thyratrons (rectifiers) in a ring magnet power supply. A phase lock loop develops a smooth ac signal of frequency equal to and in phase with the frequency of the voltage wave developed by the main generator of the power supply. A counter that counts from zero to a particular number each cycle of the main generator voltage wave is synchronized with the smooth AC signal of the phase lock loop. Gates compare the number in the counter with predetermined desired firing angles for each thyratron and with coincidence the proper thyratron is fired at the predetermined firing angle.

Standardization and determination of the total internal conversion coefficient of In-111.

PubMed

Matos, Izabela T; Koskinas, Marina F; Nascimento, Tatiane S; Yamazaki, Ione M; Dias, Mauro S

2014-05-01

The standardization of (111)In by means of a 4πβ-γ coincidence system, composed of a proportional counter in 4π geometry, coupled to a 20% relative efficiency HPGe crystal, for measuring gamma-rays is presented. The data acquisition was performed by means of the software coincidence system (SCS) and the activity was determined by the extrapolation technique. Two gamma-ray windows were selected: at 171 keV and 245 keV total absorption peaks, allowing the determination of the total internal conversion coefficient for these two gamma transitions. The results were compared with those available in the literature. © 2013 Published by Elsevier Ltd.

STS-100 crewmembers prepare to train in NBL

NASA Image and Video Library

2000-12-01

JSC2000-07391 (1 December 2000)--- Astronaut Chris A. Hadfield, representing the Canadian Space Agency (CSA), puts final touches on the suit-up process in preparation for a training session in the Neutral Buoyancy Laboratory (NBL) near the Johnson Space Center (JSC). Hadfield is designated for space walk duty on the STS-100 flight, and underwater simulations of his duties help prepare him for the mission, scheduled for spring of next year. By coincidence, Hadfield is aligned beneath the Canadian flag, one of the many on NBL walls which pay tribute to the participating international partners.

Vocalizations produced by humpback whale (Megaptera novaeangliae) calves recorded in Hawaii.

PubMed

Zoidis, Ann M; Smultea, Mari A; Frankel, Adam S; Hopkins, Julia L; Day, Andy; McFarland, A Sasha; Whitt, Amy D; Fertl, Dagmar

2008-03-01

Although humpback whale (Megaptera novaeangliae) calves are reported to vocalize, this has not been measurably verified. During March 2006, an underwater video camera and two-element hydrophone array were used to record nonsong vocalizations from a mother-calf escort off Hawaii. Acoustic data were analyzed; measured time delays between hydrophones provided bearings to 21 distinct vocalizations produced by the male calf. Signals were pulsed (71%), frequency modulated (19%), or amplitude modulated (10%). They were of simple structure, low frequency (mean=220 Hz), brief duration (mean=170 ms), and relatively narrow bandwidth (mean=2 kHz). The calf produced three series of "grunts" when approaching the diver. During winters of the years 2001-2005 in Hawaii, nonsong vocalizations were recorded in 109 (65%) of 169 groups with a calf using an underwater video and single (omnidirectional) hydrophone. Nonsong vocalizations were most common (34 of 39) in lone mother-calf pairs. A subsample from this dataset of 60 signals assessed to be vocalizations provided strong evidence that 10 male and 18 female calves vocalized based on statistical similarity to the 21 verified calf signals, proximity to an isolated calf (27 of 28 calves), strong signal-to-noise ratio, and/or bubble emissions coincident to sound.

Variations in AmLi source spectra and their estimation utilizing the 5 Ring Multiplicity Counter

NASA Astrophysics Data System (ADS)

Weinmann-Smith, R.; Beddingfield, D. H.; Enqvist, A.; Swinhoe, M. T.

2017-06-01

Active-mode assay systems are widely used for the safeguards of uranium items to verify compliance with the Non-Proliferation Treaty. Systems such as the Active-Well Coincidence Counter (AWCC) and the Uranium Neutron Coincidence Collar (UNCL) use americium-lithium (AmLi) neutron sources to induce fissions which are measured to determine the sample mass. These systems have historically relied on calibrations derived from well-defined standards. Recently, restricted access to standards or more difficult measurements have resulted in a reliance on modeling and simulation for the calibration of systems, which introduces potential simulation biases. The AmLi source energy spectra commonly used in the safeguards community do not accurately represent measurement results and the spectrum uncertainty can represent a large contribution to the total modeling uncertainty in active-mode systems. The 5-Ring Multiplicity Counter (5RMC) has been used to measure 17 AmLi sources. The measurements showed a significant spectral variation between different sources. Utilization of a spectrum that is specific to an individual source or a series of sources will give improved results over historical general spectra when modeling AmLi sources. Candidate AmLi neutron spectra were calculated in MCNP and SOURCES4C for a range of physical AmLi characteristics. The measurement and simulation data were used to fit reliable and accurate AmLi spectra for use in the simulation of active-mode systems. Spectra were created for average Gammatron C, Gammatron N, and MRC series sources, and for individual sources. The systematic uncertainty introduced by physical aspects of the AmLi source were characterized through simulations. The accuracy of spectra from the literature was compared.

The effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting

DOE PAGES

Croft, Stephen; Favalli, Andrea; Swinhoe, Martyn T.; ...

2016-01-13

In neutron coincidence counting using the shift register autocorrelation technique, a predelay is inserted before the opening of the (R+A)-gate. Operationally the purpose of the predelay is to ensure that the (R+A)- and A-gates have matched effectiveness, otherwise a bias will result when the difference between the gates is used to calculate the accidentals corrected net reals coincidence rate. The necessity for the predelay was established experimentally in the early practical development and deployment of the coincidence counting method. The choice of predelay for a given detection system is usually made experimentally, but even today long standing traditional values (e.g.,more » 4.5 µs) are often used. This, at least in part, reflects the fact that a deep understanding of why a finite predelay setting is needed and how to control the underlying influences has not been fully worked out. We attempt, in this paper, to gain some insight into the problem. One aspect we consider is the slowing down, thermalization, and diffusion of neutrons in the detector moderator. The other is the influence of deadtime and electronic transients. These may be classified as non-ideal detector behaviors because they are not included in the conventional model used to interpret measurement data. From improved understanding of the effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting, the performance of both future and current coincidence counters may be improved.« less

The effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting

NASA Astrophysics Data System (ADS)

Croft, Stephen; Favalli, Andrea; Swinhoe, Martyn T.; Goddard, Braden; Stewart, Scott

2016-04-01

In neutron coincidence counting using the shift register autocorrelation technique, a predelay is inserted before the opening of the (R+A)-gate. Operationally the purpose of the predelay is to ensure that the (R+A)- and A-gates have matched effectiveness, otherwise a bias will result when the difference between the gates is used to calculate the accidentals corrected net reals coincidence rate. The necessity for the predelay was established experimentally in the early practical development and deployment of the coincidence counting method. The choice of predelay for a given detection system is usually made experimentally, but even today long standing traditional values (e.g., 4.5 μs) are often used. This, at least in part, reflects the fact that a deep understanding of why a finite predelay setting is needed and how to control the underlying influences has not been fully worked out. In this paper we attempt to gain some insight into the problem. One aspect we consider is the slowing down, thermalization, and diffusion of neutrons in the detector moderator. The other is the influence of deadtime and electronic transients. These may be classified as non-ideal detector behaviors because they are not included in the conventional model used to interpret measurement data. From improved understanding of the effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting, the performance of both future and current coincidence counters may be improved.

Defining the uncertainty of electro-optical identification system performance estimates using a 3D optical environment derived from satellite

NASA Astrophysics Data System (ADS)

Ladner, S. D.; Arnone, R.; Casey, B.; Weidemann, A.; Gray, D.; Shulman, I.; Mahoney, K.; Giddings, T.; Shirron, J.

2009-05-01

Current United States Navy Mine-Counter-Measure (MCM) operations primarily use electro-optical identification (EOID) sensors to identify underwater targets after detection via acoustic sensors. These EOID sensors which are based on laser underwater imaging by design work best in "clear" waters and are limited in coastal waters especially with strong optical layers. Optical properties and in particular scattering and absorption play an important role on systems performance. Surface optical properties alone from satellite are not adequate to determine how well a system will perform at depth due to the existence of optical layers. The spatial and temporal characteristics of the 3d optical variability of the coastal waters along with strength and location of subsurface optical layers maximize chances of identifying underwater targets by exploiting optimum sensor deployment. Advanced methods have been developed to fuse the optical measurements from gliders, optical properties from "surface" satellite snapshot and 3-D ocean circulation models to extend the two-dimensional (2-D) surface satellite optical image into a three-dimensional (3-D) optical volume with subsurface optical layers. Modifications were made to an EOID performance model to integrate a 3-D optical volume covering an entire region of interest as input and derive system performance field. These enhancements extend present capability based on glider optics and EOID sensor models to estimate the system's "image quality". This only yields system performance information for a single glider profile location in a very large operational region. Finally, we define the uncertainty of the system performance by coupling the EOID performance model with the 3-D optical volume uncertainties. Knowing the ensemble spread of EOID performance field provides a new and unique capability for tactical decision makers and Navy Operations.

Bulk muscles, loose cables

PubMed Central

Liyanage, Chamari R D G; Kodali, Venkata

2014-01-01

The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. PMID:25326558

Bulk muscles, loose cables.

PubMed

Liyanage, Chamari R D G; Kodali, Venkata

2014-10-17

The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. 2014 BMJ Publishing Group Ltd.

The influence of underwater data transmission sounds on the displacement behaviour of captive harbour seals (Phoca vitulina).

PubMed

Kastelein, Ronald A; van der Heul, Sander; Verboom, Willem C; Triesscheijn, Rob J V; Jennings, Nancy V

2006-02-01

To prevent grounding of ships and collisions between ships in shallow coastal waters, an underwater data collection and communication network (ACME) using underwater sounds to encode and transmit data is currently under development. Marine mammals might be affected by ACME sounds since they may use sound of a similar frequency (around 12 kHz) for communication, orientation, and prey location. If marine mammals tend to avoid the vicinity of the acoustic transmitters, they may be kept away from ecologically important areas by ACME sounds. One marine mammal species that may be affected in the North Sea is the harbour seal (Phoca vitulina). No information is available on the effects of ACME-like sounds on harbour seals, so this study was carried out as part of an environmental impact assessment program. Nine captive harbour seals were subjected to four sound types, three of which may be used in the underwater acoustic data communication network. The effect of each sound was judged by comparing the animals' location in a pool during test periods to that during baseline periods, during which no sound was produced. Each of the four sounds could be made into a deterrent by increasing its amplitude. The seals reacted by swimming away from the sound source. The sound pressure level (SPL) at the acoustic discomfort threshold was established for each of the four sounds. The acoustic discomfort threshold is defined as the boundary between the areas that the animals generally occupied during the transmission of the sounds and the areas that they generally did not enter during transmission. The SPLs at the acoustic discomfort thresholds were similar for each of the sounds (107 dB re 1 microPa). Based on this discomfort threshold SPL, discomfort zones at sea for several source levels (130-180 dB re 1 microPa) of the sounds were calculated, using a guideline sound propagation model for shallow water. The discomfort zone is defined as the area around a sound source that harbour seals are expected to avoid. The definition of the discomfort zone is based on behavioural discomfort, and does not necessarily coincide with the physical discomfort zone. Based on these results, source levels can be selected that have an acceptable effect on harbour seals in particular areas. The discomfort zone of a communication sound depends on the sound, the source level, and the propagation characteristics of the area in which the sound system is operational. The source level of the communication system should be adapted to each area (taking into account the width of a sea arm, the local sound propagation, and the importance of an area to the affected species). The discomfort zone should not coincide with ecologically important areas (for instance resting, breeding, suckling, and feeding areas), or routes between these areas.

Analysis of calibration data for the uranium active neutron coincidence counting collar with attention to errors in the measured neutron coincidence rate

DOE PAGES

Croft, Stephen; Burr, Thomas Lee; Favalli, Andrea; ...

2015-12-10

We report that the declared linear density of 238U and 235U in fresh low enriched uranium light water reactor fuel assemblies can be verified for nuclear safeguards purposes using a neutron coincidence counter collar in passive and active mode, respectively. The active mode calibration of the Uranium Neutron Collar – Light water reactor fuel (UNCL) instrument is normally performed using a non-linear fitting technique. The fitting technique relates the measured neutron coincidence rate (the predictor) to the linear density of 235U (the response) in order to estimate model parameters of the nonlinear Padé equation, which traditionally is used to modelmore » the calibration data. Alternatively, following a simple data transformation, the fitting can also be performed using standard linear fitting methods. This paper compares performance of the nonlinear technique to the linear technique, using a range of possible error variance magnitudes in the measured neutron coincidence rate. We develop the required formalism and then apply the traditional (nonlinear) and alternative approaches (linear) to the same experimental and corresponding simulated representative datasets. Lastly, we find that, in this context, because of the magnitude of the errors in the predictor, it is preferable not to transform to a linear model, and it is preferable not to adjust for the errors in the predictor when inferring the model parameters« less

LaCl3:Ce Coincidence Signatures to Calibrate Gamma-ray Detectors

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

McIntyre, Justin I.; Schrom, Brian T.; Cooper, Matthew W.

Abstract Calibrating the gamma-ray detection efficiency of radiation detectors in a field environment is difficult under most circumstances. To counter this problem we have developed a technique that uses a Cerium doped Lanthanum-Tri-Chloride (LaCl3:Ce) scintillation detector to provide gated gammas[ , ]. Exploiting the inherent radioactivity of the LaCl3:Ce due to the long-lived radioactive isotope 138La (t1/2 = 1.06 x 1011 yrs) allows the use of the 788 and 1436-keV gammas as a measure of efficiency. In this paper we explore the effectiveness of using the beta-gamma coincidences radiation LaCl3:Ce detector to calibrate the energy and efficiency of a numbermore » of gamma-ray detectors.« less

Maritime and Underwater Cultural Heritage in South Africa: The Development of Relevant Management Strategies in the Historical Maritime Context of the Southern Tip of Africa

NASA Astrophysics Data System (ADS)

Sharfman, Jonathan; Boshoff, Jaco; Parthesius, Robert

2012-10-01

South Africans have a long association with water. It has provided a source of food, a medium for trade and a catalyst for migration and development. The country's geographical position as a crossroads of maritime trade between Europe and the East means that its history is inextricably linked to the history of the rest of the world. The result is a multi-faceted representation of sites, objects and mythologies related to water and maritime heritage that reflect not only local historical and social development, but global cultural change as well. Given the importance of South Africa's underwater cultural heritage (UCH), managers have grappled with management principles, ethics and theoretical models in an effort to produce and enforce heritage legislation that is relevant and effective. This paper outlines South Africa's maritime context from 1.5 million years ago until the present, summarises legislative and mitigation developments over the past half century and provides details of current trends in maritime archaeology and UCH management at the southern tip of Africa. Training programmes and public awareness are keys to this strategy to bring UCH and maritime archaeology into the mainstream and counter treasure hunting and looting of this rich, friable resource.

High-Resolution Seafloor Mapping at A Deep-Sea Methane Seep Field with an Autonomous Underwater Vehicle

NASA Astrophysics Data System (ADS)

Skarke, A. D.

2017-12-01

A growing body of research indicates that points of seafloor gas emission, known as cold-seeps, are a common feature along many continental margins. Results from recent exploration efforts show that benthic environments at cold-seeps are characterized by extensive authigenic carbonate crusts and complex chemosynthetic communities. The seafloor morphology and geophysical properties of these locations are heterogeneous and relatively complex due to the three-dimensional structure created by carbonate buildups and dense bivalve beds. Seeps are often found clustered and the spatial extent of associated seafloor crusts and beds can reach multiple square kilometers. Here, the results of a 1.25 km2 autonomous underwater vehicle (AUV) survey of a deep-sea methane seep field with 13 vents, at a nominal depth of 1400 m, located near Veatch Canyon on the US Atlantic margin are presented. Multibeam sonar, sidescan sonar, and a sub bottom profiler on the AUV were used to make high-resolution observations of seafloor bathymetry (resolution 1m2) as well as water column, seafloor, and subsurface acoustic backscatter intensity. Additionally, a downward oriented camera was used to collect seafloor imagery coincident with acoustic observations at select locations. Acoustic results indicated the location of discrete gas plumes as well as a continuous area of elevated seafloor roughness and backscatter intensity consistent with the presence of large scale authigenic rock outcrops and extensive mussel beds, which were visually confirmed with camera imagery. Additionally, a linear area of particularly elevated seafloor roughness and acoustic backscatter intensity that lies sub-parallel to an adjacent ridge was interpreted to be controlled by underlying geologic processes such as soft sediment faulting. Automated analysis of camera imagery and coincident acoustic backscatter and bathymetry data as well as derivative metrics (e.g. slope and rugosity) was used to segment and classify bed type (carbonate rock, sediment, mussel bed), yielding insight into geologic and ecological processes within the seep field study area.

Renormalization of the inflationary perturbations revisited

NASA Astrophysics Data System (ADS)

Markkanen, Tommi

2018-05-01

In this work we clarify aspects of renormalization on curved backgrounds focussing on the potential ramifications on the amplitude of inflationary perturbations. We provide an alternate view of the often used adiabatic prescription by deriving a correspondence between the adiabatic subtraction terms and traditional renormalization. Specifically, we show how adiabatic subtraction can be expressed as a set of counter terms that are introduced by redefining the bare parameters of the action. Our representation of adiabatic subtraction then allows us to easily find other renormalization prescriptions differing only in the finite parts of the counter terms. As our main result, we present for quadratic inflation how one may consistently express the renormalization of the spectrum of perturbations from inflation as a redefinition of the bare cosmological constant and Planck mass such that the observable predictions coincide with the unrenormalized result.

Development of the cosmic ray techniques

NASA Technical Reports Server (NTRS)

Rossi, B.

1982-01-01

It has been found that most advances of cosmic-ray physics have been directly related to the development of observational techniques. The history of observational techniques is discussed, taking into account ionization chambers, refinements applied to ionization chambers to make them suitable for an effective use in the study of cosmic radiation, the Wulf-type electrometer, the electrometer designed by Millikan and Neher, the Geiger-Mueller counter, the experiment of Bothe and Kolhoerster, the coincidence circuit, and a cosmic-ray 'telescope'. Attention is given to a magnetic lens for cosmic rays, a triangular arrangement of Geiger-Mueller counters used to demonstrate the production of a secondary radiation, a stereoscopic cloud-chamber photograph of showers, the cloud-chamber picture which provided the first evidence of the positive electron, and arrangements for studying photon components, mu-mesons, and air showers.

Half-life measurement of 212Pb by means of a liquid scintillator-based 220Rn trap.

PubMed

Kossert, Karsten

2017-07-01

A beaker was filled with a liquid mineral oil scintillator to catch 220 Rn from a 228 Th source. The liquid scintillator was then transferred to a polyethylene vial which was measured in a custom-built triple-to-double coincidence ratio (TDCR) counter. The measurements were used to determine the 212 Pb half-life which was found to be 10.622(7) hours. Copyright © 2017 Elsevier Ltd. All rights reserved.

CHICO2, a two-dimensional pixelated parallel-plate avalanche counter

DOE PAGES

Wu, C. Y.; Cline, D.; Hayes, A.; ...

2016-01-27

CHICO 2 (Compact Heavy Ion COunter), is a large solid-angle, charged-particle detector array developed to provide both θ and Φ angle resolutions matching those of GRETINA (Gamma-Ray Energy Tracking In-beam Nuclear Array). CHICO 2 was successfully tested at the Argonne National Laboratory where it was fielded as an auxiliary detector with GRETINA for γ-ray spectroscopic studies of nuclei using a 252Cf spontaneous fission source, stable beams, and radioactive beams from CARIBU. In field tests of the 72,76Ge beams on a 0.5 mg/cm 2208Pb target at the sub-barrier energy, CHICO 2 provided charged-particle angle resolutions (FWHM) of 1.55° in θ andmore » 2.47° in Φ. This achieves the design goal for both coordinates assuming a beam-spot size (>3 mm) and the target thickness (>0.5 mg/cm 2). The combined angular resolution of GRETINA/CHICO 2 resulted in a Doppler-shift corrected energy resolution of 0.60% for 1 MeV coincident de-excitation γ-rays. This is nearly a factor of two improvements in resolution and sensitivity compared to Gammasphere/CHICO. Kinematically-coincident detection of scattered ions by CHICO 2 still maintains the mass resolution (ΔM/M) of ~5% that enhanced isolation of scattered weak beams of interest from scattered contaminant beams.« less

Fast coincidence counting with active inspection systems

NASA Astrophysics Data System (ADS)

Mullens, J. A.; Neal, J. S.; Hausladen, P. A.; Pozzi, S. A.; Mihalczo, J. T.

2005-12-01

This paper describes 2nd and 3rd order time coincidence distributions measurements with a GHz processor that synchronously samples 5 or 10 channels of data from radiation detectors near fissile material. On-line, time coincidence distributions are measured between detectors or between detectors and an external stimulating source. Detector-to-detector correlations are useful for passive measurements also. The processor also measures the number of times n pulses occur in a selectable time window and compares this multiplet distribution to a Poisson distribution as a method of determining the occurrence of fission. The detectors respond to radiation emitted in the fission process induced internally by inherent sources or by external sources such as LINACS, DT generators either pulsed or steady state with alpha detectors, etc. Data can be acquired from prompt emission during the source pulse, prompt emissions immediately after the source pulse, or delayed emissions between source pulses. These types of time coincidence measurements (occurring on the time scale of the fission chain multiplication processes for nuclear weapons grade U and Pu) are useful for determining the presence of these fissile materials and quantifying the amount, and are useful for counter terrorism and nuclear material control and accountability. This paper presents the results for a variety of measurements.

LIDAR and acoustics applications to ocean productivity

NASA Technical Reports Server (NTRS)

Collins, D. J.

1982-01-01

The requirements for the submersible, the instrumentation necessary to perform these measurements, and the optical and acoustical technology required to develop the ocean color scanner instrumentation are described. The development of a second generation ocean color scanner produced the need for coincident in situ scientific measurements which examine the primary productivity of the upper ocean on time and space scales which are large compared to the environmental scales. The vertical and horizontal variability of the biota, including the relationship between chlorophyll and primary productivity, the productivity of zooplankton, and the dynamic interaction between phytoplankton and zooplankton, and between these populations and the physical environment are investigated. A towed submersible will be constructed which accommodates both an underwater LIDAR instrument and a multifrequency sonar.

Measuring the radon concentration in air meting van de radonconcentratie in lucht

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

Aten, J.B.T.; Bierhuizen, H.W.J.; Vanhoek, L.P.

1975-01-01

A simple transportable apparatus for measurement of the radon concentration in the air of a workshop was developed. An air sample is sucked through a filter and the decay curve of the alpha activity is measured. The counting speed 40 min after sampling gives an indication of the radon activity. The apparatus was calibrated by analyzing an analogous decay curve obtained with a big filter and a big air sample, the activity being measured with an anti-coincidence counter. (GRA)

Fissile material detector

DOEpatents

Ivanov, Alexander I.; Lushchikov, Vladislav I.; Shabalin, Eugeny P.; Maznyy, Nikita G.; Khvastunov, Michael M.; Rowland, Mark

2002-01-01

A detector for fissile materials which provides for integrity monitoring of fissile materials and can be used for nondestructive assay to confirm the presence of a stable content of fissile material in items. The detector has a sample cavity large enough to enable assay of large items of arbitrary configuration, utilizes neutron sources fabricated in spatially extended shapes mounted on the endcaps of the sample cavity, incorporates a thermal neutron filter insert with reflector properties, and the electronics module includes a neutron multiplicity coincidence counter.

Comparison of aerosol volume size distributions retrieved from ground-based remote sensing measurements with those from an optical particle counter on the ground

NASA Astrophysics Data System (ADS)

Kim, B.; Choi, Y.; Ghim, Y.

2013-12-01

Both Cimel CE-318 sunphotometer and POM-02 skyradiometer were operated for around 15 months starting from March 2012 as a part of the DRAGON (Distributed Regional Aerosol Gridded Observation Networks) campaign. These two instruments were collocated at the Hankuk_UFS (Hankuk University of Foreign Studies) site of AERONET (AErosol RObotic NETwork,) and the YGN (Yongin) site of SKYNET (SKYradiometer NETwork). We have also measured the particle concentration on the ground using an optical particle counter (Grimm Model 1.108) since the beginning of this year. The measurement site (37.02 °N, 127.16 °E, 167 m above sea level) is located about 35 km southeast of downtown Seoul. We compare the volume size distributions from sunphotometer, skyradiometer, and optical particle counter for the former part of this year. In the retrieval process, AERONET assumes 22 bins for 0.05-15 μm while SKYNET assumes 20 bins for 0.01-20 μm. The optical particle counter measures the particle number concentrations between 0.25 and 32 μm in 31 bins. Since the measurement intervals are different between instruments, we compare the distributions when the measurement time coincides within 5 minutes as well as mean distributions from the instruments. We examine the differences in mode radii and volume concentrations of fine and coarse mode aerosols between instruments.

Soft X-ray astronomy proportional counter electronics

NASA Technical Reports Server (NTRS)

Gardner, W. R.

1971-01-01

The X-ray multiwire proportional counter is designed to measure cosmic X-ray fluxes at sounding rocket altitudes in the energy range of 0.1 to 10 keV. Four instruments will be launched in a Black Brant 4 rocket employing different combinations of detector windows and gas. The detector is constructed with two layers of twelve cells. A columnator is mounted on the face of one layer whose cells are wired together alternately to form two main detector sections. The electronics and gas regulation systems are mounted on the face of the second layer whose cells are wired together to form one anticoincidence detector section. Normally X-rays will have short ionization paths in only one of the main detector cells at a time and won't enter the anticoincidence detector cells. To distinguish between X-rays and charged particles, the instrument includes a coincidence discriminator, an anticoincidence discriminator, and a pulse rise time discriminator.

An experiment to study the nuclear component of primary cosmic rays

NASA Technical Reports Server (NTRS)

Paul, J. M.; Verma, S. D.

1971-01-01

An apparatus has been designed and is being fabricated to study the charge composition, fluxes, and energy spectra of light nuclei in the energy region from 1 GeV to 100 GeV. The apparatus essentially consists of an array of a large number of particle detectors operated in coincidence and serving as a charged particle telescope. A mosaic silicon semiconductor detector, a plastic scintillation counter and a lucite Cerenkov detector are used to measure the charges of the incident nuclei. Two one-inch thick CsI detectors are used to study low energy particles. An ionization spectrometer is utilized to measure primary energies in the 1 to 100 GeV energy interval. A gas Cerenkov counter is being designed to distinguish between electrons and protons. It is planned to calibrate the apparatus at an accelerator using particles of known energy.

Characterizations of double pulsing in neutron multiplicity and coincidence counting systems

DOE PAGES

Koehler, Katrina E.; Henzl, Vladimir; Croft, Stephen; ...

2016-06-29

Passive neutron coincidence/multiplicity counters are subject to non-ideal behavior, such as double pulsing and dead time. It has been shown in the past that double-pulsing exhibits a distinct signature in a Rossi-alpha distribution, which is not readily noticed using traditional Multiplicity Shift Register analysis. But, it has been assumed that the use of a pre-delay in shift register analysis removes any effects of double pulsing. Here, we use high-fidelity simulations accompanied by experimental measurements to study the effects of double pulsing on multiplicity rates. By exploiting the information from the double pulsing signature peak observable in the Rossi-alpha distribution, themore » double pulsing fraction can be determined. Algebraic correction factors for the multiplicity rates in terms of the double pulsing fraction have been developed. We also discuss the role of these corrections across a range of scenarios.« less

FPGA-based gating and logic for multichannel single photon counting

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

Pooser, Raphael C; Earl, Dennis Duncan; Evans, Philip G

2012-01-01

We present results characterizing multichannel InGaAs single photon detectors utilizing gated passive quenching circuits (GPQC), self-differencing techniques, and field programmable gate array (FPGA)-based logic for both diode gating and coincidence counting. Utilizing FPGAs for the diode gating frontend and the logic counting backend has the advantage of low cost compared to custom built logic circuits and current off-the-shelf detector technology. Further, FPGA logic counters have been shown to work well in quantum key distribution (QKD) test beds. Our setup combines multiple independent detector channels in a reconfigurable manner via an FPGA backend and post processing in order to perform coincidencemore » measurements between any two or more detector channels simultaneously. Using this method, states from a multi-photon polarization entangled source are detected and characterized via coincidence counting on the FPGA. Photons detection events are also processed by the quantum information toolkit for application testing (QITKAT)« less

An instrument for continuous measurement of 220Rn (and 222Rn) using delayed coincidences between 220Rn and 216Po

NASA Astrophysics Data System (ADS)

Bigu, J.; Elliott, J.

1994-05-01

An instrument has been developed for continuous monitoring of 220Rn. The method of data analysis is based on delayed coincidences between 220Rn and 216Po. The instrument basically consists of a scaler equipped with a photomultiplier tube (PMT) to which a scintillation cell (SC) of the flow through type is optically coupled. The scaler is equipped with a pulse output (P/O) port which provides a TTL pulse, +5 V in amplitude and 5 to 10 μs duration for each nuclear event recorded by the SC and its associated electronic circuitry. The P/O port is connected to a 32 bit counter/timer unit operating at 1 MHz which records and stores the time of arrival of pulses. For laboratory use, the counter/timer is connected to the serial port of a laptop PC. However, for field applications, where space and weight pose severe practical limitations, the PC is substituted by an expanded counter/timer unit which incorporates a muprocessor for data analysis, a LCD for data display, and a keypad to key in function instructions. Furthermore, some additional hardware permits the measurement of 220Rn flux density, J( 220Rn) , from soils and other materials. Because total α-particle count, as well as delayed (α - α) coincidence rates are recorded in two separate channels, the method permits the measurement of 222Rn in addition to 220Rn. The method is particularly useful for low concentration levels. The sensitivity of the method primarily depends on the volume of the SC. For a low volume SC (˜0.16 l), a sensitivity of 0.2 h -1/Bq m -3 for 220Rn and 1.4 h -1/Bq m -3 for 222Rn are readily attainable. For a large volume (1.5 l) SC (external PMT used), the sensitivity for 220Rn is ≥ 1.5 h -1/Bq m -3, depending on the SC design and the operating sampling flowrate. (Note: h -1 stands for counts per hour). The above instrument has been used extensively at the National Radon/Thoron Test Facility (NRTTF) of the Elliot Lake Laboratory for routine monitoring of 220Rn levels since 1992. It has also been used for outdoor and indoor 220Rn measurements, as well as for the determination of J( 220Rn) from earthen materials and the like.

Estimating the Effective System Dead Time Parameter for Correlated Neutron Counting

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

Croft, Stephen; Cleveland, Steve; Favalli, Andrea

We present that neutron time correlation analysis is one of the main technical nuclear safeguards techniques used to verify declarations of, or to independently assay, special nuclear materials. Quantitative information is generally extracted from the neutron-event pulse train, collected from moderated assemblies of 3He proportional counters, in the form of correlated count rates that are derived from event-triggered coincidence gates. These count rates, most commonly referred to as singles, doubles and triples rates etc., when extracted using shift-register autocorrelation logic, are related to the reduced factorial moments of the time correlated clusters of neutrons emerging from the measurement items. Correctingmore » these various rates for dead time losses has received considerable attention recently. The dead time losses for the higher moments in particular, and especially for large mass (high rate and highly multiplying) items, can be significant. Consequently, even in thoughtfully designed systems, accurate dead time treatments are needed if biased mass determinations are to be avoided. In support of this effort, in this paper we discuss a new approach to experimentally estimate the effective system dead time of neutron coincidence counting systems. It involves counting a random neutron source (e.g. AmLi is a good approximation to a source without correlated emission) and relating the second and higher moments of the neutron number distribution recorded in random triggered interrogation coincidence gates to the effective value of dead time parameter. We develop the theoretical basis of the method and apply it to the Oak Ridge Large Volume Active Well Coincidence Counter using sealed AmLi radionuclide neutron sources and standard multiplicity shift register electronics. The method is simple to apply compared to the predominant present approach which involves using a set of 252Cf sources of wide emission rate, it gives excellent precision in a conveniently short time, and it yields consistent results as a function of the order of the moment used to extract the dead time parameter. In addition, this latter observation is reassuring in that it suggests the assumptions underpinning the theoretical analysis are fit for practical application purposes. However, we found that the effective dead time parameter obtained is not constant, as might be expected for a parameter that in the dead time model is characteristic of the detector system, but rather, varies systematically with gate width.« less

Estimating the Effective System Dead Time Parameter for Correlated Neutron Counting

DOE PAGES

Croft, Stephen; Cleveland, Steve; Favalli, Andrea; ...

2017-04-29

We present that neutron time correlation analysis is one of the main technical nuclear safeguards techniques used to verify declarations of, or to independently assay, special nuclear materials. Quantitative information is generally extracted from the neutron-event pulse train, collected from moderated assemblies of 3He proportional counters, in the form of correlated count rates that are derived from event-triggered coincidence gates. These count rates, most commonly referred to as singles, doubles and triples rates etc., when extracted using shift-register autocorrelation logic, are related to the reduced factorial moments of the time correlated clusters of neutrons emerging from the measurement items. Correctingmore » these various rates for dead time losses has received considerable attention recently. The dead time losses for the higher moments in particular, and especially for large mass (high rate and highly multiplying) items, can be significant. Consequently, even in thoughtfully designed systems, accurate dead time treatments are needed if biased mass determinations are to be avoided. In support of this effort, in this paper we discuss a new approach to experimentally estimate the effective system dead time of neutron coincidence counting systems. It involves counting a random neutron source (e.g. AmLi is a good approximation to a source without correlated emission) and relating the second and higher moments of the neutron number distribution recorded in random triggered interrogation coincidence gates to the effective value of dead time parameter. We develop the theoretical basis of the method and apply it to the Oak Ridge Large Volume Active Well Coincidence Counter using sealed AmLi radionuclide neutron sources and standard multiplicity shift register electronics. The method is simple to apply compared to the predominant present approach which involves using a set of 252Cf sources of wide emission rate, it gives excellent precision in a conveniently short time, and it yields consistent results as a function of the order of the moment used to extract the dead time parameter. In addition, this latter observation is reassuring in that it suggests the assumptions underpinning the theoretical analysis are fit for practical application purposes. However, we found that the effective dead time parameter obtained is not constant, as might be expected for a parameter that in the dead time model is characteristic of the detector system, but rather, varies systematically with gate width.« less

Estimating the effective system dead time parameter for correlated neutron counting

NASA Astrophysics Data System (ADS)

Croft, Stephen; Cleveland, Steve; Favalli, Andrea; McElroy, Robert D.; Simone, Angela T.

2017-11-01

Neutron time correlation analysis is one of the main technical nuclear safeguards techniques used to verify declarations of, or to independently assay, special nuclear materials. Quantitative information is generally extracted from the neutron-event pulse train, collected from moderated assemblies of 3He proportional counters, in the form of correlated count rates that are derived from event-triggered coincidence gates. These count rates, most commonly referred to as singles, doubles and triples rates etc., when extracted using shift-register autocorrelation logic, are related to the reduced factorial moments of the time correlated clusters of neutrons emerging from the measurement items. Correcting these various rates for dead time losses has received considerable attention recently. The dead time losses for the higher moments in particular, and especially for large mass (high rate and highly multiplying) items, can be significant. Consequently, even in thoughtfully designed systems, accurate dead time treatments are needed if biased mass determinations are to be avoided. In support of this effort, in this paper we discuss a new approach to experimentally estimate the effective system dead time of neutron coincidence counting systems. It involves counting a random neutron source (e.g. AmLi is a good approximation to a source without correlated emission) and relating the second and higher moments of the neutron number distribution recorded in random triggered interrogation coincidence gates to the effective value of dead time parameter. We develop the theoretical basis of the method and apply it to the Oak Ridge Large Volume Active Well Coincidence Counter using sealed AmLi radionuclide neutron sources and standard multiplicity shift register electronics. The method is simple to apply compared to the predominant present approach which involves using a set of 252Cf sources of wide emission rate, it gives excellent precision in a conveniently short time, and it yields consistent results as a function of the order of the moment used to extract the dead time parameter. This latter observation is reassuring in that it suggests the assumptions underpinning the theoretical analysis are fit for practical application purposes. However, we found that the effective dead time parameter obtained is not constant, as might be expected for a parameter that in the dead time model is characteristic of the detector system, but rather, varies systematically with gate width.

Optical Design Considerations for Efficient Light Collection from Liquid Scintillation Counters

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

Bernacki, Bruce E.; Douglas, Matthew; Erchinger, Jennifer L.

2015-01-01

Liquid scintillation counters measure charged particle-emitting radioactive isotopes and are used for environmental studies, nuclear chemistry, and life science. Alpha and beta emissions arising from the material under study interact with the scintillation cocktail to produce light. The prototypical liquid scintillation counter employs low-level photon-counting detectors to measure the arrival of the scintillation light produced as a result of the dissolved material under study interacting with the scintillation cocktail. For reliable operation the counting instrument must convey the scintillation light to the detectors efficiently and predictably. Current best practices employ the use of two or more detectors for coincidence processingmore » to discriminate true scintillation events from background events due to instrumental effects such as photomultiplier tube dark rates, tube flashing, or other light emission not generated in the scintillation cocktail vial. In low background liquid scintillation counters additional attention is paid to shielding the scintillation cocktail from naturally occurring radioactive material (NORM) present in the laboratory and within the instruments construction materials. Low background design is generally at odds with optimal light collection. This study presents the evolution of a light collection design for liquid scintillation counting in a low background shield. The basic approach to achieve both good light collection and a low background measurement is described. The baseline signals arising from the scintillation vial are modeled and methods to efficiently collect scintillation light are presented as part of the development of a customized low-background, high sensitivity liquid scintillation counting system.« less

X-ray observations of AM Herculis from OSO-8

NASA Technical Reports Server (NTRS)

Coe, M. J.; Dennis, B. R.; Dolan, J. F.; Crannell, C. J.; Frost, K. J.; Orwig, L. E.

1979-01-01

The white dwarf binary system AM Herculis (2A1815+500) was observed in X-rays at both low energies (E less 10 keV) and higher energies. The exact shape of the spectrum, particularly at the higher energies, has yet to be determined. Results from the high energy scintillation spectrometer on OSO-8 are presented. These are combined with results published elsewhere obtained concurrently with the proportional counter on the same satellite, thereby giving for the first time coincident observations of AM Her over the range 2 to 250 keV.

Background noise levels and correlation with ship traffic in the Gulf of Catania

NASA Astrophysics Data System (ADS)

Viola, Salvatore; Buscaino, Giuseppa; Caruso, Francesco; Chierici, Francesco; Embriaco, Davide; Favali, Paolo; Giovanetti, Gabriele; Grammauta, Roasario; Larosa, Giuseppina; Pavan, Gianni; Pellegrino, Carmelo; Pulvirenti, Sara; Riccobene, Giorgio; Sciacca, Virginia; Simeone, Francesco; Beranzoli, Laura; Marinaro, Giuditta

2015-04-01

In the last decades the growing interest in the evaluation of the underwater acoustic noise for studies in the fields of geology, biology and high-energy physics is driving the scientific community to collaborate towards a multidisciplinary approach to the topic. In June 2012 in the framework of the European project EMSO, a multidisciplinary underwater observatory, named NEMO-SN1, was installed 25 km off-shore the port of Catania, at a depth of 2100 m and operated until May 2013 by INFN (Istituto Nazionale di Fisica Nucleare) and INGV (Istituto Nazionale di Geofisica e Vulcanologia). NEMO-SN1 hosted aboard geophysical, oceanographic and acoustic sensors: among these a seismic hydrophone model SMID DT-405D(V). In this work, conducted within the activity of the SMO project, the results on the evaluation of the underwater acoustic pollution in the Gulf of Catania through SMID DT-405D(V) recordings are presented. The seismic hydrophone provided a data set of about 11 months of continuous (24/7) recordings. Underwater sounds have been continuously digitized at a sampling frequency of 2 kHz and the acquired data have been stored in 10min long files for off-line analysis. To describe one-year background noise levels, the mean integrated acoustic noise was measured every second (sampling frequency 2000, NFFT 2048) in the 1/3 octave bands with centre frequency 63 Hz and for each 10 minutes-long file the 5th, the 50th and the 98th percentiles were calculated. Measured noise was correlated with the shipping traffic in the area, thanks to the data provided by an AIS receiver installed at the INFN-Laboratori Nazionali del Sud. An acoustic noise increment was measured in coincidence with the passing of crafts in the area and it was possible to identify the characteristic spectrum of each ship. A simple model for the estimation of the acoustic noise induced by the ships passing through the area was developed. The model was applied by using AIS data acquired during the operation of the NEMO-SN1 and the results of the model were compared with the experimental acoustic data. This approach paves the way for further studies on the acoustic identification of the ships producing high noise levels to find solutions to mitigate the underwater acoustic pollution. Further studies on the whole water column are foreseen, taking advantage of the data provided by the acoustic antennas that are going to be installed between 3500 m and 3000 m water depth, off-shore Portopalo di Capo Passero, in South-East Sicily.

Time correlated measurements using plastic scintillators with neutron-photon pulse shape discrimination

NASA Astrophysics Data System (ADS)

Richardson, Norman E., IV

Since the beginning of the nuclear age, there has been a strong demand for the development of efficient technologies for the detection of ionizing radiation. According to the United States' Department of Energy, the accurate assessment of fissile materials is essential in achieving the nonproliferation goals of enhancing safety and security of nuclear fuel cycle and nuclear energy facilities. Nuclear materials can be characterized by the measurement of prompt and delayed neutrons and gamma rays emitted in spontaneous or induced fission reactions and neutrons emitted in fission reactions are the distinctive signatures of nuclear materials. Today, the most widely used neutron detection technologies rely on thermal neutron capture reactions using a moderating material to cause the neutron to lose its energy prior to the detection event. This is necessary because as the fission event occurs, neutrons are emitted carrying high amounts of energy, typically on the order of mega electron volts (MeV). These energetic particles are classified as "fast" neutrons. For detecting the thermal neutrons, the Helium-3 (3He) gas-filled counters are arguably the most widely used technology of neutron detection. 3He counters have been the scientific standard for the nuclear engineering community for several decades, and have earned their place as a reliable technique for the detection of neutrons. However, 3He gas-filled counters have several disadvantages. First, gas-filled counters are not rigid and are sensitive to vibrations. Secondly, gas-filled counters are prone to the count rate limitations due to the physical processes of charge multiplication and transport in the gas medium in the electric field. Lastly, 3He gas-filled counters suffer from a supply shortage of the 3He isotope. As it is stated in [3], this shortage is created by the new demand for Helium-3 due to the deployment of neutron detectors at the borders after the 9/11 attack to help secure the nation against smuggled nuclear and radiological material. Moreover, the production of 3He isotope as a byproduct of security programs was drastically decreased. This isotope shortage coupled with the disadvantages of relying on a detector that requires neutron moderation before the detection of fission neutrons, poses a significant challenge in supporting the existing detection systems and the development of future technologies. To address this problem, a reliable and accurate alternative technology to detect neutrons emitted in fissions must be developed. One such alternative technology that shows promise in this application is the use of scintillators based on solid state materials (plastics) which are sensitive to fast neutrons. However, plastic scintillators are also sensitive to photons. Hence, it is necessary to separate the neutron signals from the photon signals, using the pulse shape discrimination (PSD) analysis. The PSD is based on the comparison of the pulse shapes of digitized signal waveforms. This approach allows for the measurement of fast neutrons without the necessity of their moderation. Because the fission spectrum neutrons are mainly fast, methods employing fast neutron detection are applicable for the assay of fissile materials. In addition, the average time of scintillation of the plastic medium is much shorter than those of the gaseous counters, thus allowing scintillation detectors to be used in high count rate environments. Furthermore, the temporal information of the fast neutron detection using multiple sensors enables the time correlation analysis of the fission neutron multiplicity. The study of time correlation measurements of fast neutrons using the array of plastic scintillators is the basis of this work. The array of four plastic scintillator detectors equipped with the digital data acquisition and analysis system was developed. The digital PSD analysis of detector signals "on-the-fly" was implemented for the array. The time coincidence measurement technique using the list mode was employed for two detectors operating on the single time scale. This was necessary as no fission source was available to be used as a fast neutron multiplicity source. The detection technology was tested using isotopic photon sources and a plutonium-beryllium neutron source. It was shown that the system can be effectively used for fast-neutron multiplicity measurements, through a "proof-of-concept" model, enabling a shorter width of the time coincidence window compared to the 3He counters. This result opens prospects to reduce the false coincidence rates in the neutron multiplicity measurements, thus increasing the sensitivity of nuclear material detection.

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

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

Quantitative NDA of isotopic neutron sources.

PubMed

Lakosi, L; Nguyen, C T; Bagi, J

2005-01-01

A non-destructive method for assaying transuranic neutron sources was developed, using a combination of gamma-spectrometry and neutron correlation technique. Source strength or actinide content of a number of PuBe, AmBe, AmLi, (244)Cm, and (252)Cf sources was assessed, both as a safety issue and with respect to combating illicit trafficking. A passive neutron coincidence collar was designed with (3)He counters embedded in a polyethylene moderator (lined with Cd) surrounding the sources to be measured. The electronics consist of independent channels of pulse amplifiers and discriminators as well as a shift register for coincidence counting. The neutron output of the sources was determined by gross neutron counting, and the actinide content was found out by adopting specific spontaneous fission and (alpha,n) reaction yields of individual isotopes from the literature. Identification of an unknown source type and constituents can be made by gamma-spectrometry. The coincidences are due to spontaneous fission in the case of Cm and Cf sources, while they are mostly due to neutron-induced fission of the Pu isotopes (i.e. self-multiplication) and the (9)Be(n,2n)(8)Be reaction in Be-containing sources. Recording coincidence rate offers a potential for calibration, exploiting a correlation between the Pu amount and the coincidence-to-total ratio. The method and the equipment were tested in an in-field demonstration exercise, with participation of national public authorities and foreign observers. Seizure of the illicit transport of a PuBe source was simulated in the exercise, and the Pu content of the source was determined. It is expected that the method could be used for identification and assay of illicit, found, or not documented neutron sources.

High-resolution frequency measurement method with a wide-frequency range based on a quantized phase step law.

PubMed

Du, Baoqiang; Dong, Shaofeng; Wang, Yanfeng; Guo, Shuting; Cao, Lingzhi; Zhou, Wei; Zuo, Yandi; Liu, Dan

2013-11-01

A wide-frequency and high-resolution frequency measurement method based on the quantized phase step law is presented in this paper. Utilizing a variation law of the phase differences, the direct different frequency phase processing, and the phase group synchronization phenomenon, combining an A/D converter and the adaptive phase shifting principle, a counter gate is established in the phase coincidences at one-group intervals, which eliminates the ±1 counter error in the traditional frequency measurement method. More importantly, the direct phase comparison, the measurement, and the control between any periodic signals have been realized without frequency normalization in this method. Experimental results show that sub-picosecond resolution can be easily obtained in the frequency measurement, the frequency standard comparison, and the phase-locked control based on the phase quantization processing technique. The method may be widely used in navigation positioning, space techniques, communication, radar, astronomy, atomic frequency standards, and other high-tech fields.

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.

Undulated Nozzle for Enhanced Exit Area Mixing

NASA Technical Reports Server (NTRS)

Seiner, John M. (Inventor); Gilinsky, Mikhail M. (Inventor)

2000-01-01

A nozzle having an undulating surface for enhancing the mixing of a primary flow with a secondary flow or ambient air, without requiring an ejector. The nozzle includes a nozzle structure and design for introducing counter-rotating vorticity into the primary flow either through (i) internal surface corrugations where an axisymmetric line through each corrugation is coincident with an axisymmetric line through the center of the flow passageway or (ii) through one or more sets of alternating convexities and cavities in the internal surface of the nozzle where an axisymmetric line through each convexity and cavity is coincident with an axisymmetric line through the center of the flow passageway, and where the convexities contract from the entrance end towards the exit end. Exit area mixing is also enhanced by one or more chevrons attached to the exit edge of the nozzle. The nozzle is ideally suited for application as a jet engine nozzle. When used as a jet engine nozzle, noise suppression with simultaneous thrust augmentation/minimal thrust loss is achieved.

Cosmic Radiation Detection and Observations

NASA Astrophysics Data System (ADS)

Ramirez Chavez, Juan; Troncoso, Maria

Cosmic rays consist of high-energy particles accelerated from remote supernova remnant explosions and travel vast distances throughout the universe. Upon arriving at earth, the majority of these particles ionize gases in the upper atmosphere, while others interact with gas molecules in the troposphere and producing secondary cosmic rays, which are the main focus of this research. To observe these secondary cosmic rays, a detector telescope was designed and equipped with two silicon photomultipliers (SiPMs). Each SiPM is coupled to a bundle of 4 wavelength shifting optical fibers that are embedded inside a plastic scintillator sheet. The SiPM signals were amplified using a fast preamplifier with coincidence between detectors established using a binary logic gate. The coincidence events were recorded with two devices; a digital counter and an Arduino micro-controller. For detailed analysis of the SiPM waveforms, a DRS4 sensory digitizer captured the waveforms for offline analysis with the CERN software package Physics Analysis Workstation in a Linux environment. Results from our experiments would be presented. Hartnell College STEM Internship Program.

Performance of coincidence-based PSD on LiF/ZnS Detectors for Multiplicity Counting

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

Robinson, Sean M.; Stave, Sean C.; Lintereur, Azaree

Abstract: Mass accountancy measurement is a nuclear nonproliferation application which utilizes coincidence and multiplicity counters to verify special nuclear material declarations. With a well-designed and efficient detector system, several relevant parameters of the material can be verified simultaneously. 6LiF/ZnS scintillating sheets may be used for this purpose due to a combination of high efficiency and short die-away times in systems designed with this material, but involve choices of detector geometry and exact material composition (e.g., the addition of Ni-quenching in the material) that must be optimized for the application. Multiplicity counting for verification of declared nuclear fuel mass involves neutronmore » detection in conditions where several neutrons arrive in a short time window, with confounding gamma rays. This paper considers coincidence-based Pulse-Shape Discrimination (PSD) techniques developed to work under conditions of high pileup, and the performance of these algorithms with different detection materials. Simulated and real data from modern LiF/ZnS scintillator systems are evaluated with these techniques and the relationship between the performance under pileup and material characteristics (e.g., neutron peak width and total light collection efficiency) are determined, to allow for an optimal choice of detector and material.« less

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

A new method for detection of distant supernova neutrino bursts

NASA Astrophysics Data System (ADS)

Cline, D.; Fenyves, E.; Foshe, T.; Fuller, G.; Meyer, B.; Wilson, J.

1990-03-01

The feasibility of astrophysical neutrino detectors is studied, which is based on the detection of neutrons produced in neutrino-nucleus inelastic scattering events. Collective nuclear effects greatly enhancing the relevant interaction cross sections over those of single particle interactions are discussed. These effects can help to reduce the mass required for neutrino detectors. An example of a simple detector based on CaCO3 neutrino targets and BF3 neutron counters is presented. Neutron background limitations are discussed and the possibility of forming a coincidence between neutrino detectors and future gravity wave detectors is also considered.

Stability analysis of hybrid-driven underwater glider

NASA Astrophysics Data System (ADS)

Niu, Wen-dong; Wang, Shu-xin; Wang, Yan-hui; Song, Yang; Zhu, Ya-qiang

2017-10-01

Hybrid-driven underwater glider is a new type of unmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steadystate operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and simulation, and to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.

Development of an artificial sensor for hydrodynamic detection inspired by a seal's whisker array.

PubMed

Eberhardt, William C; Wakefield, Brendan F; Murphy, Christin T; Casey, Caroline; Shakhsheer, Yousef; Calhoun, Benton H; Reichmuth, Colleen

2016-08-31

Nature has shaped effective biological sensory systems to receive complex stimuli generated by organisms moving through water. Similar abilities have not yet been fully developed in artificial systems for underwater detection and monitoring, but such technology would enable valuable applications for military, commercial, and scientific use. We set out to design a fluid motion sensor array inspired by the searching performance of seals, which use their whiskers to find and follow underwater wakes. This sensor prototype, called the Wake Information Detection and Tracking System (WIDTS), features multiple whisker-like elements that respond to hydrodynamic disturbances encountered while moving through water. To develop and test this system, we trained a captive harbor seal (Phoca vitulina) to wear a blindfold while tracking a remote-controlled, propeller-driven submarine. After mastering the tracking task, the seal learned to carry the WIDTS adjacent to its own vibrissal array during active pursuit of the target. Data from the WIDTS sensors describe changes in the deflection angles of the whisker elements as they pass through the hydrodynamic trail left by the submarine. Video performance data show that these detections coincide temporally with WIDTS-wake intersections. Deployment of the sensors on an actively searching seal allowed for the direct comparison of our instrument to the ability of the biological sensory system in a proof-of-concept demonstration. The creation of the WIDTS provides a foundation for instrument development in the field of biomimetic fluid sensor technology.

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.

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.

An Underwater Color Image Quality Evaluation Metric.

PubMed

Yang, Miao; Sowmya, Arcot

2015-12-01

Quality evaluation of underwater images is a key goal of underwater video image retrieval and intelligent processing. To date, no metric has been proposed for underwater color image quality evaluation (UCIQE). The special absorption and scattering characteristics of the water medium do not allow direct application of natural color image quality metrics especially to different underwater environments. In this paper, subjective testing for underwater image quality has been organized. The statistical distribution of the underwater image pixels in the CIELab color space related to subjective evaluation indicates the sharpness and colorful factors correlate well with subjective image quality perception. Based on these, a new UCIQE metric, which is a linear combination of chroma, saturation, and contrast, is proposed to quantify the non-uniform color cast, blurring, and low-contrast that characterize underwater engineering and monitoring images. Experiments are conducted to illustrate the performance of the proposed UCIQE metric and its capability to measure the underwater image enhancement results. They show that the proposed metric has comparable performance to the leading natural color image quality metrics and the underwater grayscale image quality metrics available in the literature, and can predict with higher accuracy the relative amount of degradation with similar image content in underwater environments. Importantly, UCIQE is a simple and fast solution for real-time underwater video processing. The effectiveness of the presented measure is also demonstrated by subjective evaluation. The results show better correlation between the UCIQE and the subjective mean opinion score.

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

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.

Fission of actinide nuclei using multi-nucleon transfer reactions

NASA Astrophysics Data System (ADS)

Léguillon, Romain; Nishio, Katsuhisa; Hirose, Kentaro; Orlandi, Riccardo; Makii, Hiroyuki; Nishinaka, Ichiro; Ishii, Tetsuro; Tsukada, Kazuaki; Asai, Masato; Chiba, Satoshi; Ohtsuki, Tsutomu; Araki, Shohei; Watanabe, Yukinobu; Tatsuzawa, Ryotaro; Takaki, Naoyuki

2014-09-01

We are promoting a campaign to measure fission-fragment mass distributions for neutron-rich actinide nuclei populated by transfer reactions from their ground state up to an excitation energy of several tens MeV. We thus obtain the excitation energy dependence of the mass distribution. The experiment was carried out at the 20 MV JAEA tandem facility at Tokai. We report on the data obtained in the direct reaction 18 O + 232 Th . Transfer-channels and excitation energies of the fissioning nuclei were identified using silicon dE-E detectors located at forward angle. Two fission fragments were detected in coincidence using multi-wire proportional counters. Fission fragment masses were determined by kinematic consideration. We obtained the fission fragment mass distributions for 13 nuclei from actinium to uranium and some fission barrier heights. We are promoting a campaign to measure fission-fragment mass distributions for neutron-rich actinide nuclei populated by transfer reactions from their ground state up to an excitation energy of several tens MeV. We thus obtain the excitation energy dependence of the mass distribution. The experiment was carried out at the 20 MV JAEA tandem facility at Tokai. We report on the data obtained in the direct reaction 18 O + 232 Th . Transfer-channels and excitation energies of the fissioning nuclei were identified using silicon dE-E detectors located at forward angle. Two fission fragments were detected in coincidence using multi-wire proportional counters. Fission fragment masses were determined by kinematic consideration. We obtained the fission fragment mass distributions for 13 nuclei from actinium to uranium and some fission barrier heights. Present study is supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan.

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.

Global and local skin friction diagnostics from TSP surface patterns on an underwater cylinder in crossflow

NASA Astrophysics Data System (ADS)

Miozzi, Massimo; Capone, Alessandro; Di Felice, Fabio; Klein, Christian; Liu, Tianshu

2016-12-01

A systematical method is formulated for extracting skin-friction fields from Temperature Sensitive Paint (TSP) images in the sense of time-averaging and phase-averaging. The method is applied to an underwater cylinder in crossflow at two subcritical regimes (Re = 72 000 and 144 000). TSP maps are decomposed in a time-averaged, a phase-averaged, and a random component. The asymptotic form of the energy equation at the wall provides an Euler-Lagrange equation set that is solved numerically to gain the relative skin friction time- and phase-averaged fields from the TSP surface temperature maps. The comparison of the time averaged relative skin-friction profiles with the literature data shows an excellent agreement on the whole laminar boundary layer up to the laminar separation line. Downstream of separation, time averaged results identify the secondary reattachment/separation events, which are lost in the available literature data. The periodic behavior of the skin-friction is taken, describing how the laminar separation bubble evolves by providing the time history of the laminar separation line and of the secondary reattachment/separation over the entire vortex shedding period. Instantaneous skin friction maps reveal the existence of coherent structures by capturing their footprint on the cylinder's surface. An array of Π-shaped traces marks the existence of counter-rotating, streamwise-oriented vortices just before the laminar separation line. Their interaction with the laminar boundary layer and with the separation line is briefly described. An example of the intermittent excerpt of their influence through the laminar separation line is reported.

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

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

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

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.

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.

Single underwater image enhancement based on color cast removal and visibility restoration

NASA Astrophysics Data System (ADS)

Li, Chongyi; Guo, Jichang; Wang, Bo; Cong, Runmin; Zhang, Yan; Wang, Jian

2016-05-01

Images taken under underwater condition usually have color cast and serious loss of contrast and visibility. Degraded underwater images are inconvenient for observation and analysis. In order to address these problems, an underwater image-enhancement method is proposed. A simple yet effective underwater image color cast removal algorithm is first presented based on the optimization theory. Then, based on the minimum information loss principle and inherent relationship of medium transmission maps of three color channels in an underwater image, an effective visibility restoration algorithm is proposed to recover visibility, contrast, and natural appearance of degraded underwater images. To evaluate the performance of the proposed method, qualitative comparison, quantitative comparison, and color accuracy test are conducted. Experimental results demonstrate that the proposed method can effectively remove color cast, improve contrast and visibility, and recover natural appearance of degraded underwater images. Additionally, the proposed method is comparable to and even better than several state-of-the-art methods.

ARIES NDA Robot operators` manual

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

Scheer, N.L.; Nelson, D.C.

1998-05-01

The ARIES NDA Robot is an automation device for servicing the material movements for a suite of Non-destructive assay (NDA) instruments. This suite of instruments includes a calorimeter, a gamma isotopic system, a segmented gamma scanner (SGS), and a neutron coincidence counter (NCC). Objects moved by the robot include sample cans, standard cans, and instrument plugs. The robot computer has an RS-232 connection with the NDA Host computer, which coordinates robot movements and instrument measurements. The instruments are expected to perform measurements under the direction of the Host without operator intervention. This user`s manual describes system startup, using the mainmore » menu, manual operation, and error recovery.« less

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…

Investigation of Very Fast Light Detectors: Silicon Photomultiplier and Micro PMT for a Cosmic Ray Array

NASA Astrophysics Data System (ADS)

Cervantes, Omar; Reyes, Liliana; Hooks, Tyler; Perez, Luis; Ritt, Stefan

2016-03-01

To construct a cosmic detector array using 4 scintillation detectors, we investigated 2 recent light sensor technologies from Hamamatsu, as possible readout detectors. First, we investigated several homemade versions of the multipixel photon counter (MPPC) light sensors. These detectors were either biased with internal or external high voltage power supplies. We made extensive measurements to confirm for the coincidence of the MPPC devices. Each sensor is coupled to a wavelength shifting fiber (WSF) that is embedded along a plastic scintillator sheet (30cmx60cmx1/4''). Using energetic cosmic rays, we evaluated several of these homemade detector modules placed above one another in a light proof enclosure. Next, we assembled 2 miniaturized micro photomultiplier (micro PMT), a device recently marketed by Hamamatsu. These sensors showed very fast response times. With 3 WSF embedded in scintillator sheets, we performed coincidence experiments. The detector waveforms were captured using the 5GS/sec domino ring sampler, the DRS4 and our workflow using the CERN PAW package and data analysis results would be presented. Title V Grant.

Investigation of Self Triggered Cosmic Ray Detectors using Silicon Photomultiplier

NASA Astrophysics Data System (ADS)

Knox, Adrian; Niduaza, Rommel; Hernandez, Victor; Ruiz, Daniel; Ramos, Daniel; Fan, Sewan; Fatuzzo, Laura; Ritt, Stefan

2015-04-01

The silicon photomultiplier (SiPM) is a highly sensitive light detector capable of measuring single photons. It costs a fraction of the photomultiplier tube and operates slightly above the breakdown voltage. At this conference we describe our investigation of SiPM, the multipixel photon counters (MPPC) from Hamamatsu as readout detectors for plastic scintillators working for detecting cosmic ray particles. Our setup consists of scintillator sheets embedded with blue to green wavelength shifting fibers optically coupled to MPPCs to detect scintillating light. Four detector assemblies would be constructed and arranged to work in self triggered mode. Using custom matching tee boxes, the amplified MPPC signals are fed to discriminators with threshold set to give a reasonable coincidence count rate. Moreover, the detector waveforms are digitized using a 5 Giga Samples per second waveform digitizer, the DRS4, and triggered with the coincidence logic to capture the MPPC waveforms. Offline analysis of the digitized waveforms is accomplished using the CERN package PAW and results of our experiments and the data analysis would also be discussed. US Department of Education Title V Grant Number PO31S090007.

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.

Directly measuring melt at a vertical face tidewater glacier: is it possible?

NASA Astrophysics Data System (ADS)

Sutherland, D.; Amundson, J. M.; Duncan, D.; Jackson, R. H.; Kienholz, C.; Motyka, R. J.; Nash, J. D.

2017-12-01

Direct observations of melt on the underwater portion of tidewater glaciers have proved elusive, mostly due to the inherent dangers of making measurements next to a calving ice front. Additionally, the melting process itself is often masked by large ice speeds, variable calving across the glacier front, and enhanced melting due to rising subglacial discharge plumes. Here, we use repeat multibeam sonar images of LeConte Glacier to assess the possibility of measuring terminus melt in situ. LeConte Glacier is a fast-moving tidewater system in southeast Alaska with ice speeds of 25 m d-1 and previously estimated submarine melting that accounts for 50% of ice loss at the front. In August 2016, May 2017, and September 2017, we conducted intensive fieldwork at the 1.5 km long, 250 m deep glacier front, collecting dozens of repeat multibeam images of the underwater terminus. Combined with coincident time-lapse photography and surface radar measurements, we attempt to disentangle the ambient melt at the glacier face from ice motion and calving. We use a suite of oceanographic observations of the emerging subglacial discharge plume to separate portions of the glacier front that show evidence of enhanced melting versus portions outside of the affected plume areas. We find a complex, time-varying geometry, with regions of undercutting, overcutting, and large discharge channels. Measurements like these are critical to i) improving numerical model parameterizations of coupled glacier-ocean interactions and ii) developing a process-based understanding of how the literal ice-ocean boundary evolves in time and space.

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.

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 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.

Performance analysis of a multispectral system for mine detection in the littoral zone

NASA Astrophysics Data System (ADS)

Hargrove, John T.; Louchard, Eric

2004-09-01

Science & Technology International (STI) has developed, under contract with the Office of Naval Research, a system of multispectral airborne sensors and processing algorithms capable of detecting mine-like objects in the surf zone. STI has used this system to detect mine-like objects in a littoral environment as part of blind tests at Kaneohe Marine Corps Base Hawaii, and Panama City, Florida. The airborne and ground subsystems are described. The detection algorithm is graphically illustrated. We report on the performance of the system configured to operate without a human in the loop. A subsurface (underwater bottom proud mine in the surf zone and moored mine in shallow water) mine detection capability is demonstrated in the surf zone, and in shallow water with wave spillage and foam. Our analysis demonstrates that this STI-developed multispectral airborne mine detection system provides a technical foundation for a viable mine counter-measures system for use prior to an amphibious assault.

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

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 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.

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.

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

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.

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

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.

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.

Quantitative non-destructive assay of PuBe neutron sources

NASA Astrophysics Data System (ADS)

Lakosi, László; Bagi, János; Nguyen, Cong Tam

2006-02-01

PuBe neutron sources were assayed, using a combination of high resolution γ-spectrometry (HRGS) and neutron correlation technique. In a previous publication [J. Bagi, C. Tam Nguyen, L. Lakosi, Nucl. Instr. and Meth. B 222 (2004) 242] a passive neutron well-counter was reported with 3He tubes embedded in a polyamide (TERRAMID) moderator (lined inside with Cd) surrounding the sources to be measured. Gross and coincidence neutron counting was performed, and the Pu content of the sources was found out from isotope analysis and by adopting specific (α, n) reaction yields of the Pu isotopes and 241Am in Be, based on supplier's information and literature data. The method was further developed and refined. Evaluation algorithm was more precisely worked out. The contribution of secondary (correlated) neutrons to the total neutron output was derived from the coincidence (doubles) count rate and taken into account in assessing the Pu content. A new evaluation of former results was performed. Assay was extended to other PuBe sources, and new results were added. In order to attain higher detection efficiency, a more efficient moderator was also applied, with and without Cd shielding around the assay chamber. Calibration seems possible using neutron measurements only (without γ-spectrometry), based on a correlation between the Pu amount and the coincidence-to-total ratio. It is expected that the method could be used for Pu accountancy and safeguards verification as well as identification and assay of seized, found, or not documented PuBe neutron sources.

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.

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

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

Underwater Nondestructive Testing of Ship Hull Welds

DTIC Science & Technology

1979-09-01

Norske Veritas. 5. Alan Taylor , Underwater Testing, Marine rechnology (Germany) Dec 1971, pp. 251-2. 6. Ship Underwater Maintenance, Evaluation and Repair...11. Peters, V. "NDT for Offshore Drilling Platform Structure," Welding end Metal Fabricatior, Jul 1973, V. 41-7. 12. Taylor , A., "Underwater...N. Cordea, Chairman, Senior Staff MetalZlugiet, ARMCO INC., Middletown, OH Mr. W. C. Brayton , Aset. to Gener•l Manager, Bethlehem Steel Corp

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.

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.

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.

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.

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.

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.

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.

Assessing sound exposure from shipping in coastal waters using a single hydrophone and Automatic Identification System (AIS) data.

PubMed

Merchant, Nathan D; Witt, Matthew J; Blondel, Philippe; Godley, Brendan J; Smith, George H

2012-07-01

Underwater noise from shipping is a growing presence throughout the world's oceans, and may be subjecting marine fauna to chronic noise exposure with potentially severe long-term consequences. The coincidence of dense shipping activity and sensitive marine ecosystems in coastal environments is of particular concern, and noise assessment methodologies which describe the high temporal variability of sound exposure in these areas are needed. We present a method of characterising sound exposure from shipping using continuous passive acoustic monitoring combined with Automatic Identification System (AIS) shipping data. The method is applied to data recorded in Falmouth Bay, UK. Absolute and relative levels of intermittent ship noise contributions to the 24-h sound exposure level are determined using an adaptive threshold, and the spatial distribution of potential ship sources is then analysed using AIS data. This technique can be used to prioritize shipping noise mitigation strategies in coastal marine environments. Copyright © 2012 Elsevier Ltd. All rights reserved.

Multiple field-based methods to assess the potential impacts of seismic surveys on scallops.

PubMed

Przeslawski, Rachel; Huang, Zhi; Anderson, Jade; Carroll, Andrew G; Edmunds, Matthew; Hurt, Lynton; Williams, Stefan

2018-04-01

Marine seismic surveys are an important tool to map geology beneath the seafloor and manage petroleum resources, but they are also a source of underwater noise pollution. A mass mortality of scallops in the Bass Strait, Australia occurred a few months after a marine seismic survey in 2010, and fishing groups were concerned about the potential relationship between the two events. The current study used three field-based methods to investigate the potential impact of marine seismic surveys on scallops in the region: 1) dredging and 2) deployment of Autonomous Underwater Vehicles (AUVs) were undertaken to examine the potential response of two species of scallops (Pecten fumatus, Mimachlamys asperrima) before, two months after, and ten months after a 2015 marine seismic survey; and 3) MODIS satellite data revealed patterns of sea surface temperatures from 2006-2016. Results from the dredging and AUV components show no evidence of scallop mortality attributable to the seismic survey, although sub-lethal effects cannot be excluded. The remote sensing revealed a pronounced thermal spike in the eastern Bass Strait between February and May 2010, overlapping the scallop beds that suffered extensive mortality and coinciding almost exactly with dates of operation for the 2010 seismic survey. The acquisition of in situ data coupled with consideration of commercial seismic arrays meant that results were ecologically realistic, while the paired field-based components (dredging, AUV imagery) provided a failsafe against challenges associated with working wholly in the field. This study expands our knowledge of the potential environmental impacts of marine seismic survey and will inform future applications for marine seismic surveys, as well as the assessment of such applications by regulatory authorities. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Towards Restoration of Missing Underwater Forests

PubMed Central

Vergés, Adriana; Coleman, Melinda A.; Steinberg, Peter D.

2014-01-01

Degradation of natural habitats due to urbanization is a major cause of biodiversity loss. Anthropogenic impacts can drive phase shifts from productive, complex ecosystems to less desirable, less diverse systems that provide fewer services. Macroalgae are the dominant habitat-forming organisms on temperate coastlines, providing habitat and food to entire communities. In recent decades, there has been a decline in macroalgal cover along some urbanised shorelines, leading to a shift from diverse algal forests to more simple turf algae or barren habitats. Phyllospora comosa, a major habitat forming macroalga in south-eastern Australia, has disappeared from the urban shores of Sydney. Its disappearance is coincident with heavy sewage outfall discharges along the metropolitan coast during 1970s and 1980s. Despite significant improvements in water-quality since that time, Phyllospora has not re-established. We experimentally transplanted adult Phyllospora into two rocky reefs in the Sydney metropolitan region to examine the model that Sydney is now suitable for the survival and recruitment of Phyllospora and thus assess the possibility of restoring Phyllospora back onto reefs where it was once abundant. Survival of transplanted individuals was high overall, but also spatially variable: at one site most individuals were grazed, while at the other site survival was similar to undisturbed algae and procedural controls. Transplanted algae reproduced and recruitment rates were higher than in natural populations at one experimental site, with high survival of new recruits after almost 18 months. Low supply and settlement success of propagules in the absence of adults and herbivory (in some places) emerge as three potential processes that may have been preventing natural re-establishment of this alga. Understanding of the processes and interactions that shape this system are necessary to provide ecologically sensible goals and the information needed to successfully restore these underwater forests. PMID:24416198

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.

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.

Innovations in the Assay of Un-Segregated Multi-Isotopic Grade TRU Waste Boxes with SuperHENC and FRAM Technology

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

Simpson, A. P.; Barber, S.; Abdurrahman, N. M.

2006-07-01

The Super High Efficiency Neutron Coincidence Counter (SuperHENC) was originally developed by BIL Solutions Inc., Los Alamos National Laboratory (LANL) and Rocky Flats Environmental Technology Site (RFETS) for assay of transuranic (TRU) waste in Standard Waste Boxes (SWB) at Rocky Flats. This mobile system was a key component in the shipment of over 4,000 SWBs to the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. The system was WIPP certified in 2001 and operated at the site for four years. The success of this system, a passive neutron coincidence counter combined with high resolution gamma spectroscopy, led to themore » order of two new units, delivered to Hanford in 2004. Several new challenges were faced at Hanford: For example, the original RFETS system was calibrated for segregated waste streams such that metals, plastics, wet combustibles and dry combustibles were separated by 'Item Description Codes' prior to assay. Furthermore, the RFETS mission of handling only weapons grade plutonium, enabled the original SuperHENC to benefit from the use of known Pu isotopics. Operations at Hanford, as with most other DOE sites, generate un-segregated waste streams, with a wide diversity of Pu isotopics. Consequently, the new SuperHENCs are required to deal with new technical challenges. The neutron system's software and calibration methodology have been modified to encompass these new requirements. In addition, PC-FRAM software has been added to the gamma system, providing a robust isotopic measurement capability. Finally a new software package has been developed that integrates the neutron and gamma data to provide a final assay results and analysis report. The new system's performance has been rigorously tested and validated against WIPP quality requirements. These modifications, together with the mobile platform, make the new SuperHENC far more versatile in handling diverse waste streams and allow for rapid redeployment around the DOE complex. (authors)« less

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

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

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.

Field transportable beta spectrometer. Innovative technology summary report

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

NONE

1998-12-01

The objective of the Large-Scale Demonstration Project (LSDP) is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) Chicago Pile-5 Test Reactor (CP-5). The purpose of the LSDP is to demonstrate that by using innovative and improved deactivation and decommissioning (D and D) technologies from various sources, significant benefits can be achieved when compared to baseline D and D technologies. One such capability being addressed by the D and D Focus Area is rapid characterization for facility contaminants. The technology was field demonstrated during the period January 7 through January 9, 1997, and offers several potentialmore » benefits, including faster turn-around time, cost reduction, and reduction in secondary waste. This report describes a PC controlled, field-transportable beta counter-spectrometer which uses solid scintillation coincident counting and low-noise photomultiplier tubes to count element-selective filters and other solid media. The dry scintillation counter used in combination with an element-selective technology eliminates the mess and disposal costs of liquid scintillation cocktails. Software in the instrument provides real-time spectral analysis. The instrument can detect and measure Tc-99, Sr-90, and other beta emitters reaching detection limits in the 20 pCi range (with shielding). Full analysis can be achieved in 30 minutes. The potential advantages of a field-portable beta counter-spectrometer include the savings gained from field generated results. The basis for decision-making is provided with a rapid turnaround analysis in the field. This technology would be competitive with the radiometric analysis done in fixed laboratories and the associated chain of custody operations.« less

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.

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

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

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

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.

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.

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

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.

Feasibility of in situ beta ray measurements in underwater environment.

PubMed

Park, Hye Min; Park, Ki Hyun; Kang, Sung Won; Joo, Koan Sik

2017-09-01

We describe an attempt at the development of an in situ detector for beta ray measurements in underwater environment. The prototype of the in situ detector is based on a CaF2: Eu scintillator using crystal light guide and Si photomultiplier. Tests were conducted using various reference sources for evaluating the linearity and stability of the detector in underwater environment. The system is simple and stable for long-term monitoring, and consumes low power. We show here an effective detection distance of 7 mm and a 2.273 MeV end-point energy spectrum of 90 Sr/ 90 Y when using the system underwater. The results demonstrate the feasibility of in situ beta ray measurements in underwater environment and can be applied for designing an in situ detector for radioactivity measurement in underwater environment. The in situ detector can also have other applications such as installation on the marine monitoring platform and quantitative analysis of radionuclides. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

A biomimetic underwater vehicle actuated by waves with ionic polymer-metal composite soft sensors.

PubMed

Shen, Qi; Wang, Tianmiao; Kim, Kwang J

2015-09-28

The ionic polymer-metal composite (IPMC) is a soft material based actuator and sensor and has a promising potential in underwater application. This paper describes a hybrid biomimetic underwater vehicle that uses IPMCs as sensors. Propelled by the energy of waves, this underwater vehicle does not need an additional energy source. A physical model based on the hydrodynamics of the vehicle was developed, and simulations were conducted. Using the Poisson-Nernst-Planck system of equations, a physics model for the IPMC sensor was proposed. For this study, experimental apparatus was developed to conduct hydrodynamic experiments for both the underwater vehicle and the IPMC sensors. By comparing the experimental and theoretical results, the speed of the underwater vehicle and the output of the IPMC sensors were well predicted by the theoretical models. A maximum speed of 1.08 × 10(-1) m s(-1) was recorded experimentally at a wave frequency of 1.6 Hz. The peak output voltage of the IPMC sensor was 2.27 × 10(-4) V, recorded at 0.8 Hz. It was found that the speed of the underwater vehicle increased as the wave frequency increased and the IPMC output decreased as the wave frequency increased. Further, the energy harvesting capabilities of the underwater vehicle hosting the IPMCs were tested. A maximum power of 9.50 × 10(-10) W was recorded at 1.6 Hz.

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

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

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

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.

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

Human Injury Criteria for Underwater Blasts

PubMed Central

Lance, Rachel M.; Capehart, Bruce; Kadro, Omar; Bass, Cameron R.

2015-01-01

Underwater blasts propagate further and injure more readily than equivalent air blasts. Development of effective personal protection and countermeasures, however, requires knowledge of the currently unknown human tolerance to underwater blast. Current guidelines for prevention of underwater blast injury are not based on any organized injury risk assessment, human data or experimental data. The goal of this study was to derive injury risk assessments for underwater blast using well-characterized human underwater blast exposures in the open literature. The human injury dataset was compiled using 34 case reports on underwater blast exposure to 475 personnel, dating as early as 1916. Using severity ratings, computational reconstructions of the blasts, and survival information from a final set of 262 human exposures, injury risk models were developed for both injury severity and risk of fatality as functions of blast impulse and blast peak overpressure. Based on these human data, we found that the 50% risk of fatality from underwater blast occurred at 302±16 kPa-ms impulse. Conservatively, there is a 20% risk of pulmonary injury at a kilometer from a 20 kg charge. From a clinical point of view, this new injury risk model emphasizes the large distances possible for potential pulmonary and gut injuries in water compared with air. This risk value is the first impulse-based fatality risk calculated from human data. The large-scale inconsistency between the blast exposures in the case reports and the guidelines available in the literature prior to this study further underscored the need for this new guideline derived from the unique dataset of actual injuries in this study. PMID:26606655

Experimental and Numerical Analyses of Dynamic Deformation and Failure in Marine Structures Subjected to Underwater Impulsive Loads

DTIC Science & Technology

2012-08-01

based impulsive loading ......................................... 48 4.4 Computational modeling of USLS ...56 4.5 Underwater Shock Loading Simulator ( USLS ) ...................................................... 59 4.6 Concluding...42 Figure 4.1 Schematic of Underwater Shock Loading Simulator ( USLS ). A high-velocity projectile hits the flyer-plate and creates a stress

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

NASA Technical Reports Server (NTRS)

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

1979-01-01

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

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.…

OD-ing on Reality: An Interview with Alex Flinn

ERIC Educational Resources Information Center

Lesesne, Teri S.

2005-01-01

Alex Flinn discusses her debut novel, Breathing Underwater, which received much critical acclaim. She absolutely felt like her second book was being compared to Breathing Underwater at first. Breaking Point (which was completed before Breathing Underwater was published) was very different in tone. It was darker. The voice was different. The ending…

Wide Area Detection and Identification of Underwater UXO Using Structural Acoustic Sensors

DTIC Science & Technology

2011-02-01

measurements of underwater unexploded ordnance (UXO),” J. Acoustic. Soc. Am. 123, 738-746 (2008). 10. R. J. Urick , “Principles of Underwater Sound... Urick , op. cit., pp 291-327. 14. S. Dey and D.K. Datta, “A parrallel hp-FEM infrastructure for three-dimensional structural acoustics,” Int. J

Underwater Munitions Expert System to Predict Mobility and Burial

DTIC Science & Technology

2017-11-14

exposure and aggregation for underwater munitions. 15. SUBJECT TERMS Underwater Munitions, Mobility, Burial, Application Programmer Interface...Munitions Expert System: Demonstration and Evaluation Report Acronyms API – Application Programmer Interface APL – Applied Physics...comparisons and traditional metrics such as the coefficient of correlation. The summary statistic for the comparisons of burial results

46 CFR 71.50-3 - Drydock examination, internal structural examination, underwater survey, and alternate hull exam...

Code of Federal Regulations, 2010 CFR

2010-10-01

..., underwater survey, and alternate hull exam intervals. 71.50-3 Section 71.50-3 Shipping COAST GUARD...-3 Drydock examination, internal structural examination, underwater survey, and alternate hull exam... wooden hulls must undergo two drydock and two internal structural examinations within any five year...

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

ERIC Educational Resources Information Center

Jabba Molinares, Daladier

2009-01-01

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

77 FR 38236 - Special Local Regulation, Underwater Music Festival, Carr Inlet, Cutts Island, WA

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-27

...-AA08 Special Local Regulation, Underwater Music Festival, Carr Inlet, Cutts Island, WA AGENCY: Coast... ensure the safety of the maritime public during the Underwater Music Festival and would do so by... Music Festival is an event which includes musical performances from a barge. Spectators approach the...

Using side-scan sonar to characterize and map physical habitat and anthropogenic underwater features in the St. Louis River.

EPA Science Inventory

Characterizing underwater habitat and other features is difficult and costly, especially in the large St. Louis River Estuary. We are using side-scan sonar (SSS), first developed in the 1960s to remotely sense underwater habitat features from reflected acoustic signals (backscatt...

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.

Mechanically durable underwater superoleophobic surfaces based on hydrophilic bulk metals for oil/water separation

NASA Astrophysics Data System (ADS)

Yu, Huadong; Lian, Zhongxu; Xu, Jinkai; Wan, Yanling; Wang, Zuobin; Li, Yiquan; Yu, Zhanjiang; Weng, Zhankun

2018-04-01

Despite the success of previous methods for fabricating underwater superoleophobic surfaces, most of the surfaces based on soft materials are prone to collapse and deformation due to their mechanically fragile nature, and they fail to perform their designed functions after the surface materials are damaged in water. In this work, the nanosecond laser-induced oxide coatings on hydrophilic bulk metals are reported which overcomes the limitation and shows the robust underwater superoleophobicity to a mechanical challenge encountered by surfaces deployed in water environment. The results show that the surface materials have the advantage that the underwater superoleophobicity is still preserved after the surfaces are scratched by knife or sandpaper and even completely destroyed because of the hydrophilic property of damaged materials in water. It is important that the results provide a guide for the design of durable underwater superoleophobic surfaces, and the development of superoleophobic materials in many potential applications such as the oil-repellent and the oil/water separation. Additionally, the nanosecond laser technology is simple, cost-effective and suitable for the large-area and mass fabrication of mechanically durable underwater superoleophobic metal materials.

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

Hydrostatic weighing at residual volume and functional residual capacity.

PubMed

Thomas, T R; Etheridge, G L

1980-07-01

Hydrostatic weighing (HW) was performed at both residual volume (RV) and functional residual capacity (FRC) to determine if underwater weighing at different lung volumes affected the measurement of body density. Subjects were 43 males, 18-25 yr. Subjects were submerged in the prone position, and the lung volume was measured by helium dilution at the time of the underwater weighing. Underwater weight was first assessed at FRC followed by assessment at RV. Changes in lung volume were accurately reflected in the underwater weight. Body density (D) was not different with the use of the FRC (mean D = 1.0778) or RV (mean D = 1.0781) data. Percent fat values for the FRC and RV data were 9.3 +/- 5.4 and 9.2 +/- 5.1%, respectively, and were not statistically different. The results indicate that the difference between percent fat determinations by HW in the prone position at FRC and RV is negligible. Because measurement of underwater weight at FRC is more comfortable for the subject, this may be the method of choice when the lung volume can be measured during the underwater weighing.

AUV Underwater Positioning Algorithm Based on Interactive Assistance of SINS and LBL

PubMed Central

Zhang, Tao; Chen, Liping; Li, Yao

2015-01-01

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. PMID:26729120

Trade-off Analysis of Underwater Acoustic Sensor Networks

NASA Astrophysics Data System (ADS)

Tuna, G.; Das, R.

2017-09-01

In the last couple of decades, Underwater Acoustic Sensor Networks (UASNs) were started to be used for various commercial and non-commercial purposes. However, in underwater environments, there are some specific inherent constraints, such as high bit error rate, variable and large propagation delay, limited bandwidth capacity, and short-range communications, which severely degrade the performance of UASNs and limit the lifetime of underwater sensor nodes as well. Therefore, proving reliability of UASN applications poses a challenge. In this study, we try to balance energy consumption of underwater acoustic sensor networks and minimize end-to-end delay using an efficient node placement strategy. Our simulation results reveal that if the number of hops is reduced, energy consumption can be reduced. However, this increases end-to-end delay. Hence, application-specific requirements must be taken into consideration when determining a strategy for node deployment.

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 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.

Study on Underwater Image Denoising Algorithm Based on Wavelet Transform

NASA Astrophysics Data System (ADS)

Jian, Sun; Wen, Wang

2017-02-01

This paper analyzes the application of MATLAB in underwater image processing, the transmission characteristics of the underwater laser light signal and the kinds of underwater noise has been described, the common noise suppression algorithm: Wiener filter, median filter, average filter algorithm is brought out. Then the advantages and disadvantages of each algorithm in image sharpness and edge protection areas have been compared. A hybrid filter algorithm based on wavelet transform has been proposed which can be used for Color Image Denoising. At last the PSNR and NMSE of each algorithm has been given out, which compares the ability to de-noising

Preparations for Underwater EVA training for the STS 41-G crew

NASA Image and Video Library

1984-07-05

S84-36900 (29 June 1984) ---Astronauts Robert L. Crippen (right) and Jon A. McBride, crew commander and pilot, respectively, for NASA's 41-G Space Shuttle mission, don self contained underwater breathing apparatus (SCUBA) gear prior to their underwater to observe a simulation of an extravehicular activity (EVA) to be performed on their mission. Astronauts Kathryn D. Sullivan and David C. Leestma, two of three mission specialists on the seven-member crew, are scheduled for the EVA. The underwater training took place in the Johnson Space Center's weightless environment training facility (WET-F).

Underwater optical communications using orbital angular momentum-based spatial division multiplexing

NASA Astrophysics Data System (ADS)

Willner, Alan E.; Zhao, Zhe; Ren, Yongxiong; Li, Long; Xie, Guodong; Song, Haoqian; Liu, Cong; Zhang, Runzhou; Bao, Changjing; Pang, Kai

2018-02-01

In this paper, we review high-capacity underwater optical communications using orbital angular momentum (OAM)-based spatial division multiplexing. We discuss methods to generate and detect blue-green optical data-carrying OAM beams as well as various underwater effects, including attenuation, scattering, current, and thermal gradients on OAM beams. Attention is also given to the system performance of high-capacity underwater optical communication links using OAM-based space division multiplexing. The paper closes with a discussion of a digital signal processing (DSP) algorithm to mitigate the inter-mode crosstalk caused by thermal gradients.

A Secure Communication Suite for Underwater Acoustic Sensor Networks

PubMed Central

Dini, Gianluca; Duca, Angelica Lo

2012-01-01

In this paper we describe a security suite for Underwater Acoustic Sensor Networks comprising both fixed and mobile nodes. The security suite is composed of a secure routing protocol and a set of cryptographic primitives aimed at protecting the confidentiality and the integrity of underwater communication while taking into account the unique characteristics and constraints of the acoustic channel. By means of experiments and simulations based on real data, we show that the suite is suitable for an underwater networking environment as it introduces limited, and sometimes negligible, communication and power consumption overhead. PMID:23202204

Remote Control over Underwater Dynamic Attachment/Detachment and Locomotion.

PubMed

Ma, Yanfei; Ma, Shuanhong; Wu, Yang; Pei, Xiaowei; Gorb, Stanislav N; Wang, Zuankai; Liu, Weimin; Zhou, Feng

2018-06-19

Despite extensive efforts to mimic the fascinating adhesion capability of geckos, the development of reversible adhesives underwater has long been lagging. The appearance of mussels-inspired dopamine chemistry has provided the feasibility to fabricate underwater adhesives; however, for such a system, imitating the reversible and fast dynamic attachment/detachment mechanism of gecko feet still remains unsolved. Here, by synthesizing a thermoresponsive copolymer of poly(dopamine methacrylamide-co-methoxyethyl-acrylate-co-N-isopropyl acrylamide) and then decorating it onto mushroom-shaped poly(dimethylsiloxane) pillar arrays, a novel underwater thermoresponsive gecko-like adhesive (TRGA) can be fabricated, yielding high adhesion during the attachment state above the lower critical solution temperature (LCST) of the copolymer, yet low adhesion during the detachment state below the LCST of the copolymer. By integrating the Fe 3 O 4 nanoparticles into the TRGA, TRGAs responsive to near-infrared laser radiation can be engineered, which can be successfully used for rapid and reversible remote control over adhesion so as to capture and release heavy objects underwater because of the contrast force change of both the normal adhesion force and the lateral friction force. It is also demonstrated that the material can be assembled on the tracks of an underwater mobile device to realize controllable movement. This opens up the door for developing intelligent underwater gecko-like locomotion with dynamic attachment/detachment ability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

L2-LBMT: A Layered Load Balance Routing Protocol for underwater multimedia data transmission

NASA Astrophysics Data System (ADS)

Lv, Ze; Tang, Ruichun; Tao, Ye; Sun, Xin; Xu, Xiaowei

2017-12-01

Providing highly efficient underwater transmission of mass multimedia data is challenging due to the particularities of the underwater environment. Although there are many schemes proposed to optimize the underwater acoustic network communication protocols, from physical layer, data link layer, network layer to transport layer, the existing routing protocols for underwater wireless sensor network (UWSN) still cannot well deal with the problems in transmitting multimedia data because of the difficulties involved in high energy consumption, low transmission reliability or high transmission delay. It prevents us from applying underwater multimedia data to real-time monitoring of marine environment in practical application, especially in emergency search, rescue operation and military field. Therefore, the inefficient transmission of marine multimedia data has become a serious problem that needs to be solved urgently. In this paper, A Layered Load Balance Routing Protocol (L2-LBMT) is proposed for underwater multimedia data transmission. In L2-LBMT, we use layered and load-balance Ad Hoc Network to transmit data, and adopt segmented data reliable transfer (SDRT) protocol to improve the data transport reliability. And a 3-node variant of tornado (3-VT) code is also combined with the Ad Hoc Network to transmit little emergency data more quickly. The simulation results show that the proposed protocol can balance energy consumption of each node, effectively prolong the network lifetime and reduce transmission delay of marine multimedia data.

Cardiovascular response during submaximal underwater treadmill exercise in stroke patients.

PubMed

Yoo, Jeehyun; Lim, Kil-Byung; Lee, Hong-Jae; Kwon, Yong-Geol

2014-10-01

To evaluate the cardiovascular response during head-out water immersion, underwater treadmill gait, and land treadmill gait in stroke patients. Ten stroke patients were recruited for underwater and land treadmill gait sessions. Each session was 40 minutes long; 5 minutes for standing rest on land, 5 minutes for standing rest in water or on treadmill, 20 minutes for treadmill walking in water or on land, 5 minutes for standing rest in water or on treadmill, and 5 minutes for standing rest on land. Blood pressure (BP) and heart rate (HR) were measured during each session. In order to estimate the cardiovascular workload and myocardial oxygen demand, the rate pressure product (RPP) value was calculated by multiplying systolic BP (SBP) by HR. SBP, DBP, mean BP (mBP), and RPP decreased significantly after water immersion, but HR was unchanged. During underwater and land treadmill gait, SBP, mBP, DBP, RPP, and HR increased. However, the mean maximum increases in BP, HR and RPP of underwater treadmill walking were significantly lower than that of land treadmill walking. Stroke patients showed different cardiovascular responses during water immersion and underwater gait as opposed to standing and treadmill-walking on land. Water immersion and aquatic treadmill gait may reduce the workload of the cardiovascular system. This study suggested that underwater treadmill may be a safe and useful option for cardiovascular fitness and early ambulation in stroke rehabilitation.

Development of a highly maneuverable unmanned underwater vehicle on the basis of quad-copter dynamics

NASA Astrophysics Data System (ADS)

Amin, Osman Md; Karim, Md. Arshadul; Saad, Abdullah His

2017-12-01

At present, research on unmanned underwater vehicle (UUV) has become a significant & familiar topic for researchers from various engineering fields. UUV is of mainly two types - AUV (Autonomous Underwater vehicle) & ROV (Remotely Operated Vehicle). There exist a significant number of published research papers on UUV, where very few researchers emphasize on the ease of maneuvering and control of UUV. Maneuvering is important for underwater vehicle in avoiding obstacles, installing underwater piping system, searching undersea resources, underwater mine disposal operations, oceanographic surveys etc. A team from Dept. of Naval Architecture & Marine Engineering of MIST has taken a project to design a highly maneuverable unmanned underwater vehicle on the basis of quad-copter dynamics. The main objective of the research is to develop a control system for UUV which would be able to maneuver the vehicle in six DOF (Degrees of Freedom) with great ease. For this purpose we are not only focusing on controllability but also designing an efficient hull with minimal drag force & optimized propeller using CFD technique. Motors were selected on the basis of the simulated thrust generated by propellers in ANSYS Fluent software module. Settings for control parameters to carry out different types of maneuvering such as hovering, spiral, one point rotation about its centroid, gliding, rolling, drifting and zigzag motions were explained in short at the end.

Quantitative NDA measurements of advanced reprocessing product materials containing uranium, neptunium, plutonium, and americium

NASA Astrophysics Data System (ADS)

Goddard, Braden

The ability of inspection agencies and facility operators to measure powders containing several actinides is increasingly necessary as new reprocessing techniques and fuel forms are being developed. These powders are difficult to measure with nondestructive assay (NDA) techniques because neutrons emitted from induced and spontaneous fission of different nuclides are very similar. A neutron multiplicity technique based on first principle methods was developed to measure these powders by exploiting isotope-specific nuclear properties, such as the energy-dependent fission cross sections and the neutron induced fission neutron multiplicity. This technique was tested through extensive simulations using the Monte Carlo N-Particle eXtended (MCNPX) code and by one measurement campaign using the Active Well Coincidence Counter (AWCC) and two measurement campaigns using the Epithermal Neutron Multiplicity Counter (ENMC) with various (alpha,n) sources and actinide materials. Four potential applications of this first principle technique have been identified: (1) quantitative measurement of uranium, neptunium, plutonium, and americium materials; (2) quantitative measurement of mixed oxide (MOX) materials; (3) quantitative measurement of uranium materials; and (4) weapons verification in arms control agreements. This technique still has several challenges which need to be overcome, the largest of these being the challenge of having high-precision active and passive measurements to produce results with acceptably small uncertainties.

Prediction of gastrointestinal disease with over-the-counter diarrheal remedy sales records in the San Francisco Bay Area.

PubMed

Kirian, Michelle L; Weintraub, June M

2010-07-20

Water utilities continue to be interested in implementing syndromic surveillance for the enhanced detection of waterborne disease outbreaks. The authors evaluated the ability of sales of over-the-counter diarrheal remedies available from the National Retail Data Monitor to predict endemic and epidemic gastrointestinal disease in the San Francisco Bay Area. Time series models were fit to weekly diarrheal remedy sales and diarrheal illness case counts. Cross-correlations between the pre-whitened residual series were calculated. Diarrheal remedy sales model residuals were regressed on the number of weekly outbreaks and outbreak-associated cases. Diarrheal remedy sales models were used to auto-forecast one week-ahead sales. The sensitivity and specificity of signals, generated by observed diarrheal remedy sales exceeding the upper 95% forecast confidence interval, in predicting weekly outbreaks were calculated. No significant correlations were identified between weekly diarrheal remedy sales and diarrhea illness case counts, outbreak counts, or the number of outbreak-associated cases. Signals generated by forecasting with the diarrheal remedy sales model did not coincide with outbreak weeks more reliably than signals chosen randomly. This work does not support the implementation of syndromic surveillance for gastrointestinal disease with data available though the National Retail Data Monitor.

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

Underwater Acoustic Tracer System

DTIC Science & Technology

2009-03-13

for controlling and utilizing supercavitating projectile dynamics to produce a distinctive radiated noise signal. (2) Description of the Prior Art...metallic objects which travel relatively closely to a magnetic pickup. For larger, high speed, underwater projectiles, supercavitating underwater vehicles...have been proposed for use. The conditions for supercavitation are known in the art. Supercavitation allows for higher speeds to be sustainable

Elastic Wave Propagation Mechanisms in Underwater Acoustic Environments

DTIC Science & Technology

2015-09-30

Elastic wave propagation mechanisms in underwater acoustic environments Scott D. Frank Marist College Department of Mathematics Poughkeepsie...conversion from elastic propagation to acoustic propagation, and intense interface waves on underwater acoustic environments with elastic bottoms...acoustic propagation will be considered as a means to predict the presence of elastic ice layers. APPROACH In a cylindrically symmetric environment

Development of High Data Rate Acoustic Multiple-Input/Multiple-Output Modems

DTIC Science & Technology

2015-09-30

communication capabilities of underwater platforms and facilitate real-time adaptive operations in the ocean. OBJECTIVES The ...signaling at the transmitter and low-complexity time reversal processing at the receiver. APPROACH Underwater acoustic (UWA) communication is useful...digital communications in shallow water environments. The advancement has direct impacts on defense appliations since underwater acoustic modems

Multireceiver Acoustic Communications in Time-Varying Environments

DTIC Science & Technology

2014-06-01

Canberra, ACT, 2012, pp. 1–7. [7] W. Chen and F. Yanjun, “Physical layer design consideration for underwater acoustic sensor networks ,”3rd IEEE Int...analysis of underwater acoustic MIMO communications,”OCEANS, Sydney, NSW, 2010, pp. 1–8. [9] Wines lab (2013). Wireless networks and embedded... NETWORKS ......................................................................3 B. CHALLENGES OF UNDERWATER ACOUSTIC COMMUNICATIONS

Compact multiwire proportional counters for the detection of fission fragments

NASA Astrophysics Data System (ADS)

Jhingan, Akhil; Sugathan, P.; Golda, K. S.; Singh, R. P.; Varughese, T.; Singh, Hardev; Behera, B. R.; Mandal, S. K.

2009-12-01

Two large area multistep position sensitive (two dimensional) multiwire proportional counters have been developed for experiments involving study of fission dynamics using general purpose scattering chamber facility at IUAC. Both detectors have an active area of 20×10 cm2 and provide position signals in horizontal (X) and vertical (Y) planes, timing signal for time of flight measurements and energy signal giving the differential energy loss in the active volume. The design features are optimized for the detection of low energy heavy ions at very low gas pressures. Special care was taken in setting up the readout electronics, constant fraction discriminators for position signals in particular, to get optimum position and timing resolutions along with high count rate handling capability of low energy heavy ions. A custom made charge sensitive preamplifier, having lower gain and shorter decay time, has been developed for extracting the differential energy loss signal. The position and time resolutions of the detectors were determined to be 1.1 mm full width at half maximum (FWHM) and 1.7 ns FWHM, respectively. The detector could handle heavy ion count rates exceeding 20 kHz without any breakdown. Time of flight signal in combination with differential energy loss signal gives a clean separation of fission fragments from projectile and target like particles. The timing and position signals of the detectors are used for fission coincidence measurements and subsequent extraction of their mass, angular, and total kinetic energy distributions. This article describes systematic study of these fission counters in terms of efficiency, time resolution, count rate handling capability, position resolution, and the readout electronics. The detector has been operated with both five electrode geometry and four electrode geometry, and a comparison has been made in their performances.

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

NASA Astrophysics Data System (ADS)

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

2007-06-01

Underwater passive navigation technology is one of the important development orientations in the field of modern navigation. With the advantage of high self-determination, stealth at sea, anti-jamming and high precision, passive navigation is completely meet with actual navigation requirements. Therefore passive navigation has become a specific navigating method for underwater vehicles. The scientists and researchers in the navigating field paid more attention to it. The underwater passive navigation can provide accurate navigation information with main Inertial Navigation System (INS) for a long period, such as location and speed. Along with the development of micro-electronics technology, the navigation of AUV is given priority to INS assisted with other navigation methods, such as terrain matching navigation. It can provide navigation ability for a long period, correct the errors of INS and make AUV not emerge from the seabed termly. With terrain matching navigation technique, in the assistance of digital charts and ocean geographical characteristics sensors, we carry through underwater image matching assistant navigation to obtain the higher location precision, therefore it is content with the requirement of underwater, long-term, high precision and all-weather of the navigation system for Autonomous Underwater Vehicles. Tertian-assistant navigation (TAN) is directly dependent on the image information (map information) in the navigating field to assist the primary navigation system according to the path appointed in advance. In TAN, a factor coordinative important with the system operation is precision and practicability of the storable images and the database which produce the image data. If the data used for characteristics are not suitable, the system navigation precision will be low. Comparing with terrain matching assistant navigation system, image matching navigation system is a kind of high precision and low cost assistant navigation system, and its matching precision directly influences the final precision of integrated navigation system. Image matching assistant navigation is spatially matching and aiming at two underwater scenery images coming from two different sensors matriculating of the same scenery in order to confirm the relative displacement of the two images. In this way, we can obtain the vehicle's location in fiducial image known geographical relation, and the precise location information given from image matching location is transmitted to INS to eliminate its location error and greatly enhance the navigation precision of vehicle. Digital image data analysis and processing of image matching in underwater passive navigation is important. In regard to underwater geographic data analysis, we focus on the acquirement, disposal, analysis, expression and measurement of database information. These analysis items structure one of the important contents of underwater terrain matching and are propitious to know the seabed terrain configuration of navigation areas so that the best advantageous seabed terrain district and dependable navigation algorithm can be selected. In this way, we can improve the precision and reliability of terrain assistant navigation system. The pre-process and format transformation of digital image during underwater image matching are expatiated in this paper. The information of the terrain status in navigation areas need further study to provide the reliable data terrain characteristic and underwater overcast for navigation. Through realizing the choice of sea route, danger district prediction and navigating algorithm analysis, TAN can obtain more high location precision and probability, hence provide technological support for image matching of underwater passive navigation.

Real-Time Communication Support for Underwater Acoustic Sensor Networks †.

PubMed

Santos, Rodrigo; Orozco, Javier; Micheletto, Matias; Ochoa, Sergio F; Meseguer, Roc; Millan, Pere; Molina, And Carlos

2017-07-14

Underwater sensor networks represent an important and promising field of research due to the large diversity of underwater ubiquitous applications that can be supported by these networks, e.g., systems that deliver tsunami and oil spill warnings, or monitor submarine ecosystems. Most of these monitoring and warning systems require real-time communication in wide area networks that have a low density of nodes. The underwater communication medium involved in these networks is very harsh and imposes strong restrictions to the communication process. In this scenario, the real-time transmission of information is done mainly using acoustic signals, since the network nodes are not physically close. The features of the communication scenario and the requirements of the communication process represent major challenges for designers of both, communication protocols and monitoring and warning systems. The lack of models to represent these networks is the main stumbling block for the proliferation of underwater ubiquitous systems. This paper presents a real-time communication model for underwater acoustic sensor networks (UW-ASN) that are designed to cover wide areas with a low density of nodes, using any-to-any communication. This model is analytic, considers two solution approaches for scheduling the real-time messages, and provides a time-constraint analysis for the network performance. Using this model, the designers of protocols and underwater ubiquitous systems can quickly prototype and evaluate their solutions in an evolving way, in order to determine the best solution to the problem being addressed. The suitability of the proposal is illustrated with a case study that shows the performance of a UW-ASN under several initial conditions. This is the first analytic model for representing real-time communication in this type of network, and therefore, it opens the door for the development of underwater ubiquitous systems for several application scenarios.

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.

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.

Real-Time Communication Support for Underwater Acoustic Sensor Networks †

PubMed Central

Santos, Rodrigo; Orozco, Javier; Micheletto, Matias

2017-01-01

Underwater sensor networks represent an important and promising field of research due to the large diversity of underwater ubiquitous applications that can be supported by these networks, e.g., systems that deliver tsunami and oil spill warnings, or monitor submarine ecosystems. Most of these monitoring and warning systems require real-time communication in wide area networks that have a low density of nodes. The underwater communication medium involved in these networks is very harsh and imposes strong restrictions to the communication process. In this scenario, the real-time transmission of information is done mainly using acoustic signals, since the network nodes are not physically close. The features of the communication scenario and the requirements of the communication process represent major challenges for designers of both, communication protocols and monitoring and warning systems. The lack of models to represent these networks is the main stumbling block for the proliferation of underwater ubiquitous systems. This paper presents a real-time communication model for underwater acoustic sensor networks (UW-ASN) that are designed to cover wide areas with a low density of nodes, using any-to-any communication. This model is analytic, considers two solution approaches for scheduling the real-time messages, and provides a time-constraint analysis for the network performance. Using this model, the designers of protocols and underwater ubiquitous systems can quickly prototype and evaluate their solutions in an evolving way, in order to determine the best solution to the problem being addressed. The suitability of the proposal is illustrated with a case study that shows the performance of a UW-ASN under several initial conditions. This is the first analytic model for representing real-time communication in this type of network, and therefore, it opens the door for the development of underwater ubiquitous systems for several application scenarios. PMID:28708093

A new compact, cost-efficient concept for underwater range-gated imaging: the UTOFIA project

NASA Astrophysics Data System (ADS)

Mariani, Patrizio; Quincoces, Iñaki; Galparsoro, Ibon; Bald, Juan; Gabiña, Gorka; Visser, Andy; Jónasdóttir, Sigrun; Haugholt, Karl Henrik; Thorstensen, Jostein; Risholm, Petter; Thielemann, Jens

2017-04-01

Underwater Time Of Flight Image Acquisition system (UTOFIA) is a recently launched H2020 project (H2020 - 633098) to develop a compact and cost-effective underwater imaging system especially suited for observations in turbid environments. The UTOFIA project targets technology that can overcome the limitations created by scattering, by introducing cost-efficient range-gated imaging for underwater applications. This technology relies on a image acquisition principle that can extends the imaging range of the cameras 2-3 times respect to other cameras. Moreover, the system will simultaneously capture 3D information of the observed objects. Today range-gated imaging is not widely used, as it relies on specialised optical components making systems large and costly. Recent technology developments have made it possible a significant (2-3 times) reduction in size, complexity and cost of underwater imaging systems, whilst addressing the scattering issues at the same time. By acquiring simultaneous 3D data, the system allows to accurately measure the absolute size of marine life and their spatial relationship to their habitat, enhancing the precision of fish stock monitoring and ecology assessment, hence supporting proper management of marine resources. Additionally, the larger observed volume and the improved image quality make the system suitable for cost-effective underwater surveillance operations in e.g. fish farms, underwater infrastructures. The system can be integrated into existing ocean observatories for real time acquisition and can greatly advance present efforts in developing species recognition algorithms, given the additional features provided, the improved image quality and the independent illumination source based on laser. First applications of the most recent prototype of the imaging system will be provided including inspection of underwater infrastructures and observations of marine life under different environmental conditions.

Filming Underwater in 3d Respecting Stereographic Rules

NASA Astrophysics Data System (ADS)

Rinaldi, R.; Hordosch, H.

2015-04-01

After an experimental phase of many years, 3D filming is now effective and successful. Improvements are still possible, but the film industry achieved memorable success on 3D movie's box offices due to the overall quality of its products. Special environments such as space ("Gravity") and the underwater realm look perfect to be reproduced in 3D. "Filming in space" was possible in "Gravity" using special effects and computer graphic. The underwater realm is still difficult to be handled. Underwater filming in 3D was not that easy and effective as filming in 2D, since not long ago. After almost 3 years of research, a French, Austrian and Italian team realized a perfect tool to film underwater, in 3D, without any constrains. This allows filmmakers to bring the audience deep inside an environment where they most probably will never have the chance to be.

Underwater hydrophone location survey

NASA Technical Reports Server (NTRS)

Cecil, Jack B.

1993-01-01

The Atlantic Undersea Test and Evaluation Center (AUTEC) is a U.S. Navy test range located on Andros Island, Bahamas, and a Division of the Naval Undersea Warfare Center (NUWC), Newport, RI. The Headquarters of AUTEC is located at a facility in West Palm Beach, FL. AUTEC's primary mission is to provide the U.S. Navy with a deep-water test and evaluation facility for making underwater acoustic measurements, testing and calibrating sonars, and providing accurate underwater, surface, and in-air tracking data on surface ships, submarines, aircraft, and weapon systems. Many of these programs are in support of Antisubmarine Warfare (ASW), undersea research and development programs, and Fleet assessment and operational readiness trials. Most tests conducted at AUTEC require precise underwater tracking (plus or minus 3 yards) of multiple acoustic signals emitted with the correct waveshape and repetition criteria from either a surface craft or underwater vehicle.

Virtual Diving in the Underwater Archaeological Site of Cala Minnola

NASA Astrophysics Data System (ADS)

Bruno, F.; Lagudi, A.; Barbieri, L.; Muzzupappa, M.; Mangeruga, M.; Pupo, F.; Cozza, M.; Cozza, A.; Ritacco, G.; Peluso, R.; Tusa, S.

2017-02-01

The paper presents the application of the technologies and methods defined in the VISAS project for the case study of the underwater archaeological site of Cala Minnola located in the island of Levanzo, in the archipelago of the Aegadian Islands (Sicily, Italy). The VISAS project (http://visas-project.eu) aims to improve the responsible and sustainable exploitation of the Underwater Cultural Heritage by means the development of new methods and technologies including an innovative virtual tour of the submerged archaeological sites. In particular, the paper describes the 3D reconstruction of the underwater archaeological site of Cala Minnola and focus on the development of the virtual scene for its visualization and exploitation. The virtual dive of the underwater archaeological site allows users to live a recreational and educational experience by receiving historical, archaeological and biological information about the submerged exhibits, the flora and fauna of the place.

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.

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

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

The purpose of this study was to design and build two versions of an underwater sound recording device. The device designed is referred to as the Underwater Sound Recorder (USR), which can be connected to one or two hydrophones or other underwater sound sensors. The URS contains a 26 dB preamplifier and a user selectable gain that permits additional amplification of input to the system from 26 dB to 46 dB. Signals within the frequency range up to 15 kHz may be recorded using the USR. Examples of USR applications are monitoring underwater processes that have the potential to createmore » large pressure waves that could potentially harm fish or other aquatic life, such as underwater explosions or pile driving. Additional applications are recording sound generated by vessels or the vocalizations of some marine mammals, such as the calls from many species of whales.« less

Underwater audiogram of the California sea lion by the conditioned vocalization technique1

PubMed Central

Schusterman, Ronald J.; Balliet, Richard F.; Nixon, James

1972-01-01

Conditioning techniques were developed demonstrating that pure tone frequencies under water can exert nearly perfect control over the underwater click vocalizations of the California sea lion (Zalophus californianus). Conditioned vocalizations proved to be a reliable way of obtaining underwater sound detection thresholds in Zalophus at 13 different frequencies, covering a frequency range of 250 to 64,000 Hz. The audiogram generated by these threshold measurements suggests that under water, the range of maximal sensitivity for Zalophus lies between one and 28 kHz with best sensitivity at 16 kHz. Between 28 and 36 kHz there is a loss in sensitivity of 60 dB/octave. However, with relatively intense acoustic signals (> 38 dB re 1 μb underwater), Zalophus will respond to frequencies at least as high as 192 kHz. These results are compared with the underwater hearing of other marine mammals. ImagesFig. 1. PMID:5033891

Low-contrast underwater living fish recognition using PCANet

NASA Astrophysics Data System (ADS)

Sun, Xin; Yang, Jianping; Wang, Changgang; Dong, Junyu; Wang, Xinhua

2018-04-01

Quantitative and statistical analysis of ocean creatures is critical to ecological and environmental studies. And living fish recognition is one of the most essential requirements for fishery industry. However, light attenuation and scattering phenomenon are present in the underwater environment, which makes underwater images low-contrast and blurry. This paper tries to design a robust framework for accurate fish recognition. The framework introduces a two stage PCA Network to extract abstract features from fish images. On a real-world fish recognition dataset, we use a linear SVM classifier and set penalty coefficients to conquer data unbalanced issue. Feature visualization results show that our method can avoid the feature distortion in boundary regions of underwater image. Experiments results show that the PCA Network can extract discriminate features and achieve promising recognition accuracy. The framework improves the recognition accuracy of underwater living fishes and can be easily applied to marine fishery industry.

Underwater Electrical Safety Practices

DTIC Science & Technology

1976-01-01

under water. While advances continue in developing new and more effective underwater electrical equipment, the Navy is concerned that its underwater...levels passing through human tissue is known to alter, temporarily, the physiological function of cells. The long-term effects , if any, are unknown. Much...of the system--human physiology, equipment, procedures, and training. Human Physiology Present knowledge of the physiological effects of electrical

Determining Detection and Classification Potential of Munitions using Advanced EMI Sensors in the Underwater Environment

DTIC Science & Technology

2016-11-01

focuses on characterizing Electromagnetic Induction (EMI) responses in the underwater setting through numerical and experimental studies with the...marine EMI sensing. 15. SUBJECT TERMS Munitions Response, Electromagnetic Induction, Unexploded Ordnance, Classification 16. SECURITY CLASSIFICATION...using Advanced EMI Sensors in the Underwater Environment.” The project focuses on characterizing Electromagnetic Induction (EMI) responses in the

15 CFR Appendix A to Subpart R of... - Thunder Bay National Marine Sanctuary and Underwater Preserve Boundary Coordinates

Code of Federal Regulations, 2013 CFR

2013-01-01

... 15 Commerce and Foreign Trade 3 2013-01-01 2013-01-01 false Thunder Bay National Marine Sanctuary... SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve Pt. 922, Subpt. R, App. A Appendix A to Subpart R of Part 922—Thunder Bay National Marine Sanctuary and Underwater...

15 CFR Appendix A to Subpart R of... - Thunder Bay National Marine Sanctuary and Underwater Preserve Boundary Coordinates

Code of Federal Regulations, 2012 CFR

2012-01-01

... 15 Commerce and Foreign Trade 3 2012-01-01 2012-01-01 false Thunder Bay National Marine Sanctuary... SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve Pt. 922, Subpt. R, App. A Appendix A to Subpart R of Part 922—Thunder Bay National Marine Sanctuary and Underwater...

15 CFR Appendix A to Subpart R of... - Thunder Bay National Marine Sanctuary and Underwater Preserve Boundary Coordinates

Code of Federal Regulations, 2014 CFR

2014-01-01

... 15 Commerce and Foreign Trade 3 2014-01-01 2014-01-01 false Thunder Bay National Marine Sanctuary... SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve Pt. 922, Subpt. R, App. A Appendix A to Subpart R of Part 922—Thunder Bay National Marine Sanctuary and Underwater...

15 CFR Appendix A to Subpart R of... - Thunder Bay National Marine Sanctuary and Underwater Preserve Boundary Coordinates

Code of Federal Regulations, 2010 CFR

2010-01-01

... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Thunder Bay National Marine Sanctuary... SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve Pt. 922, Subpt. R, App. A Appendix A to Subpart R of Part 922—Thunder Bay National Marine Sanctuary and Underwater...

15 CFR Appendix A to Subpart R of... - Thunder Bay National Marine Sanctuary and Underwater Preserve Boundary Coordinates

Code of Federal Regulations, 2011 CFR

2011-01-01

... 15 Commerce and Foreign Trade 3 2011-01-01 2011-01-01 false Thunder Bay National Marine Sanctuary... SANCTUARY PROGRAM REGULATIONS Thunder Bay National Marine Sanctuary and Underwater Preserve Pt. 922, Subpt. R, App. A Appendix A to Subpart R of Part 922—Thunder Bay National Marine Sanctuary and Underwater...

GOATS 2008 Autonomous, Adaptive Multistatic Acoustic Sensing

DTIC Science & Technology

2008-09-30

To develop net-centric, autonomous underwater vehicle sensing concepts for littoral MCM and ASW, exploiting collaborative and environmentally...unlimited 13. SUPPLEMENTARY NOTES code 1 only 14. ABSTRACT To develop net-centric, autonomous underwater vehicle sensing concepts for littoral MCM and...of autonomous underwater vehicle networks as platforms for new sonar concepts exploring the full 3-D acoustic environment of shallow water (SW) and

NRL Fact Book

DTIC Science & Technology

1988-05-01

interests are centered on signal processing and the physics of underwater acoustic propagation, ambient noise, and reverberation. Mr. Rojas is a member...Airborne underwater acoustics Bottom-limited acoustics Arctic underwater acoustics Propagation Noise Ambient noise measurements and modeling Spectral...Multispectral image correlation Space sensor and mission analysis CROWN" STALK Time, ms (100 ms after impactO Time-history of the . radar backscatter from a

Maritime In Situ Sensing Inter-Operable Networks (MISSION)

DTIC Science & Technology

2013-09-30

creating acoustic communications (acomms) technologies enabling underwater sensor networks and distributed systems. Figure 1. Project MISSION...Marn, S. Ramp, F. Bahr, “Implementation of an Underwater Wireless Sensor Network in San Francisco Bay,” Proc. 10th International Mine Warfare...NILUS – An Underwater Acoustic Sensor Network Demonstrator System,” Proc. 10th International Mine Warfare Technology Symposium, Monterey, CA, May 7

System and Method for Automated Rendezvous, Docking and Capture of Autonomous Underwater Vehicles

NASA Technical Reports Server (NTRS)

Clark, Evan (Inventor); Richmond, Kristof (Inventor); Paulus, Jeremy (Inventor); Kimball, Peter (Inventor); Scully, Mark (Inventor); Kapit, Jason (Inventor); Stone, William C. (Inventor)

2018-01-01

A system for automated rendezvous, docking, and capture of autonomous underwater vehicles at the conclusion of a mission comprising of comprised of a docking rod having lighted, pulsating (in both frequency and light intensity) series of LED light strips thereon, with the LEDs at a known spacing, and the autonomous underwater vehicle specially designed to detect and capture the docking rod and then be lifted structurally by a spherical end strop about which the vehicle can be pivoted and hoisted up (e.g., onto a ship). The method of recovery allows for very routine and reliable automated recovery of an unmanned underwater asset.

A simple underwater imaging model.

PubMed

Hou, Weilin

2009-09-01

It is commonly known that underwater imaging is hindered by both absorption and scattering by particles of various origins. However, evidence also indicates that the turbulence in natural underwater environments can cause severe image-quality degradation. A model is presented to include the effects of both particle and turbulence on underwater optical imaging through optical transfer functions to help quantify the limiting factors under different circumstances. The model utilizes Kolmogorov-type index of refraction power spectra found in the ocean, along with field examples, to demonstrate that optical turbulence can limit imaging resolution by affecting high spatial frequencies. The effects of the path radiance are also discussed.

WODA Technical Guidance on Underwater Sound from Dredging.

PubMed

Thomsen, Frank; Borsani, Fabrizio; Clarke, Douglas; de Jong, Christ; de Wit, Pim; Goethals, Fredrik; Holtkamp, Martine; Martin, Elena San; Spadaro, Philip; van Raalte, Gerard; Victor, George Yesu Vedha; Jensen, Anders

2016-01-01

The World Organization of Dredging Associations (WODA) has identified underwater sound as an environmental issue that needs further consideration. A WODA Expert Group on Underwater Sound (WEGUS) prepared a guidance paper in 2013 on dredging sound, including a summary of potential impacts on aquatic biota and advice on underwater sound monitoring procedures. The paper follows a risk-based approach and provides guidance for standardization of acoustic terminology and methods for data collection and analysis. Furthermore, the literature on dredging-related sounds and the effects of dredging sounds on marine life is surveyed and guidance on the management of dredging-related sound risks is provided.

Discovery of Sound in the Sea: Resources for Educators, Students, the Public, and Policymakers.

PubMed

Vigness-Raposa, Kathleen J; Scowcroft, Gail; Miller, James H; Ketten, Darlene R; Popper, Arthur N

2016-01-01

There is increasing concern about the effects of underwater sound on marine life. However, the science of sound is challenging. The Discovery of Sound in the Sea (DOSITS) Web site ( http://www.dosits.org ) was designed to provide comprehensive scientific information on underwater sound for the public and educational and media professionals. It covers the physical science of underwater sound and its use by people and marine animals for a range of tasks. Celebrating 10 years of online resources, DOSITS continues to develop new material and improvements, providing the best resource for the most up-to-date information on underwater sound and its potential effects.

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

PubMed

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

2016-11-01

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

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.

Great cormorants ( Phalacrocorax carbo) can detect auditory cues while diving

NASA Astrophysics Data System (ADS)

Hansen, Kirstin Anderson; Maxwell, Alyssa; Siebert, Ursula; Larsen, Ole Næsbye; Wahlberg, Magnus

2017-06-01

In-air hearing in birds has been thoroughly investigated. Sound provides birds with auditory information for species and individual recognition from their complex vocalizations, as well as cues while foraging and for avoiding predators. Some 10% of existing species of birds obtain their food under the water surface. Whether some of these birds make use of acoustic cues while underwater is unknown. An interesting species in this respect is the great cormorant ( Phalacrocorax carbo), being one of the most effective marine predators and relying on the aquatic environment for food year round. Here, its underwater hearing abilities were investigated using psychophysics, where the bird learned to detect the presence or absence of a tone while submerged. The greatest sensitivity was found at 2 kHz, with an underwater hearing threshold of 71 dB re 1 μPa rms. The great cormorant is better at hearing underwater than expected, and the hearing thresholds are comparable to seals and toothed whales in the frequency band 1-4 kHz. This opens up the possibility of cormorants and other aquatic birds having special adaptations for underwater hearing and making use of underwater acoustic cues from, e.g., conspecifics, their surroundings, as well as prey and predators.

Channel coding for underwater acoustic single-carrier CDMA communication system

NASA Astrophysics Data System (ADS)

Liu, Lanjun; Zhang, Yonglei; Zhang, Pengcheng; Zhou, Lin; Niu, Jiong

2017-01-01

CDMA is an effective multiple access protocol for underwater acoustic networks, and channel coding can effectively reduce the bit error rate (BER) of the underwater acoustic communication system. For the requirements of underwater acoustic mobile networks based on CDMA, an underwater acoustic single-carrier CDMA communication system (UWA/SCCDMA) based on the direct-sequence spread spectrum is proposed, and its channel coding scheme is studied based on convolution, RA, Turbo and LDPC coding respectively. The implementation steps of the Viterbi algorithm of convolutional coding, BP and minimum sum algorithms of RA coding, Log-MAP and SOVA algorithms of Turbo coding, and sum-product algorithm of LDPC coding are given. An UWA/SCCDMA simulation system based on Matlab is designed. Simulation results show that the UWA/SCCDMA based on RA, Turbo and LDPC coding have good performance such that the communication BER is all less than 10-6 in the underwater acoustic channel with low signal to noise ratio (SNR) from -12 dB to -10dB, which is about 2 orders of magnitude lower than that of the convolutional coding. The system based on Turbo coding with Log-MAP algorithm has the best performance.

Research on the underwater target imaging based on the streak tube laser lidar

NASA Astrophysics Data System (ADS)

Cui, Zihao; Tian, Zhaoshuo; Zhang, Yanchao; Bi, Zongjie; Yang, Gang; Gu, Erdan

2018-03-01

A high frame rate streak tube imaging lidar (STIL) for real-time 3D imaging of underwater targets is presented in this paper. The system uses 532nm pulse laser as the light source, the maximum repetition rate is 120Hz, and the pulse width is 8ns. LabVIEW platform is used in the system, the system control, synchronous image acquisition, 3D data processing and display are realized through PC. 3D imaging experiment of underwater target is carried out in a flume with attenuation coefficient of 0.2, and the images of different depth and different material targets are obtained, the imaging frame rate is 100Hz, and the maximum detection depth is 31m. For an underwater target with a distance of 22m, the high resolution 3D image real-time acquisition is realized with range resolution of 1cm and space resolution of 0.3cm, the spatial relationship of the targets can be clearly identified by the image. The experimental results show that STIL has a good application prospect in underwater terrain detection, underwater search and rescue, and other fields.

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.

A bio-inspired electrocommunication system for small underwater robots.

PubMed

Wang, Wei; Liu, Jindong; Xie, Guangming; Wen, Li; Zhang, Jianwei

2017-03-29

Weakly electric fishes (Gymnotid and Mormyrid) use an electric field to communicate efficiently (termed electrocommunication) in the turbid waters of confined spaces where other communication modalities fail. Inspired by this biological phenomenon, we design an artificial electrocommunication system for small underwater robots and explore the capabilities of such an underwater robotic communication system. An analytical model for electrocommunication is derived to predict the effect of the key parameters such as electrode distance and emitter current of the system on the communication performance. According to this model, a low-dissipation, and small-sized electrocommunication system is proposed and integrated into a small robotic fish. We characterize the communication performance of the robot in still water, flowing water, water with obstacles and natural water conditions. The results show that underwater robots are able to communicate electrically at a speed of around 1 k baud within about 3 m with a low power consumption (less than 1 W). In addition, we demonstrate that two leader-follower robots successfully achieve motion synchronization through electrocommunication in the three-dimensional underwater space, indicating that this bio-inspired electrocommunication system is a promising setup for the interaction of small underwater robots.

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

PubMed Central

Wu, Geng-De; Huang, Chun-Ju

2017-01-01

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

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

PubMed

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

2017-06-22

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

Aquatic Acoustic Metrics Interface Utility for Underwater Sound Monitoring and Analysis

PubMed Central

Ren, Huiying; Halvorsen, Michele B.; Deng, Zhiqun Daniel; Carlson, Thomas J.

2012-01-01

Fishes and marine mammals may suffer a range of potential effects from exposure to intense underwater sound generated by anthropogenic activities such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording (USR) devices have been built to acquire samples of the underwater sound generated by anthropogenic activities. Software becomes indispensable for processing and analyzing the audio files recorded by these USRs. In this paper, we provide a detailed description of a new software package, the Aquatic Acoustic Metrics Interface (AAMI), specifically designed for analysis of underwater sound recordings to provide data in metrics that facilitate evaluation of the potential impacts of the sound on aquatic animals. In addition to the basic functions, such as loading and editing audio files recorded by USRs and batch processing of sound files, the software utilizes recording system calibration data to compute important parameters in physical units. The software also facilitates comparison of the noise sound sample metrics with biological measures such as audiograms of the sensitivity of aquatic animals to the sound, integrating various components into a single analytical frame. The features of the AAMI software are discussed, and several case studies are presented to illustrate its functionality. PMID:22969353

Primary standardization of 57Co.

PubMed

Koskinas, Marina F; Moreira, Denise S; Yamazaki, Ione M; de Toledo, Fábio; Brancaccio, Franco; Dias, Mauro S

2010-01-01

This work describes the method developed by the Nuclear Metrology Laboratory in IPEN, São Paulo, Brazil, for the standardization of a (57)Co radioactive solution. Cobalt-57 is a radionuclide used for calibrating gamma-ray and X-ray spectrometers, as well as a gamma reference source for dose calibrators used in nuclear medicine services. Two 4pibeta-gamma coincidence systems were used to perform the standardization, the first used a 4pi(PC) counter coupled to a pair of 76 mm x 76 mm NaI(Tl) scintillators for detecting gamma-rays, the other one used a HPGe spectrometer for gamma detection. The measurements were performed by selecting a gamma-ray window comprising the (122 keV+136 keV) total absorption energy peaks in the NaI(Tl) and selecting the total absorption peak of 122 keV in the germanium detector. The electronic system used the TAC method developed at LMN for registering the observed events. The methodology recently developed by the LMN for simulating all detection processes in a 4pibeta-gamma coincidence system, by means of the Monte Carlo technique, was applied and the behavior of extrapolation curve compared to experimental data. The final activity obtained by the Monte Carlo calculation agrees with the experimental results within the experimental uncertainty. Copyright 2009 Elsevier Ltd. All rights reserved.

Search for High-Energy Emission from GRBs with the ARGO-YBJ Detector

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

Di Girolamo, T.

2009-05-25

ARGO-YBJ is a 'full coverage' air shower detector consisting of a 6700 m{sup 2} carpet of Resistive Plate Counters, located at Yangbajing (Tibet, P.R. China, 4300 m a.s.l). Its large field of view ({approx}2 sr, limited only by the atmospheric absorption) and high duty-cycle make ARGO-YBJ particularly suitable to detect unpredictable and short duration events such as GRBs. ARGO-YBJ works using two techniques: the 'Scaler Mode', which reaches the lower energy limit ({approx}1 GeV) of the detector, and the 'Shower Mode', with an energy threshold of a few hundreds of GeV. Here we present the results of the search formore » high-energy emission from GRBs in coincidence with satellite detections.« less

3D Laser Scanner for Underwater Manipulation.

PubMed

Palomer, Albert; Ridao, Pere; Youakim, Dina; Ribas, David; Forest, Josep; Petillot, Yvan

2018-04-04

Nowadays, research in autonomous underwater manipulation has demonstrated simple applications like picking an object from the sea floor, turning a valve or plugging and unplugging a connector. These are fairly simple tasks compared with those already demonstrated by the mobile robotics community, which include, among others, safe arm motion within areas populated with a priori unknown obstacles or the recognition and location of objects based on their 3D model to grasp them. Kinect-like 3D sensors have contributed significantly to the advance of mobile manipulation providing 3D sensing capabilities in real-time at low cost. Unfortunately, the underwater robotics community is lacking a 3D sensor with similar capabilities to provide rich 3D information of the work space. In this paper, we present a new underwater 3D laser scanner and demonstrate its capabilities for underwater manipulation. In order to use this sensor in conjunction with manipulators, a calibration method to find the relative position between the manipulator and the 3D laser scanner is presented. Then, two different advanced underwater manipulation tasks beyond the state of the art are demonstrated using two different manipulation systems. First, an eight Degrees of Freedom (DoF) fixed-base manipulator system is used to demonstrate arm motion within a work space populated with a priori unknown fixed obstacles. Next, an eight DoF free floating Underwater Vehicle-Manipulator System (UVMS) is used to autonomously grasp an object from the bottom of a water tank.

An underwater optical wireless communication network

NASA Astrophysics Data System (ADS)

Arnon, Shlomi

2009-08-01

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

Underwater optical wireless communication network

NASA Astrophysics Data System (ADS)

Arnon, Shlomi

2010-01-01

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

Ocean Variability Effects on Underwater Acoustic Communications

DTIC Science & Technology

2012-09-30

2000. [2] B. Li, J. Huang, S. Zhou, K. Ball, M. Stojanovic, L. Freitag, and P. Willett. MIMO - OFDM for high rate underwater acoustic...alternative to orthogonal frequency-division multiplexing ( OFDM ) [2], we developed a multiband transceiver, where a wide frequency band is divided into...multiple separated sub-bands. These sub- bands are several kilohertz in width, much wider than OFDM sub-carriers used in underwater channels

Unmanned Underwater Vehicle (UUV) Information Study

DTIC Science & Technology

2014-11-28

Maritime Unmanned System NATO North Atlantic Treaty Organization xi The use or disclosure of the information on this sheet is subject to the... Unmanned Aerial System UDA Underwater Domain Awareness UNISIPS Unified Sonar Image Processing System USV Unmanned Surface Vehicle UUV Unmanned Underwater...data distribution to ashore systems , such as the delay, its impact and the benefits to the overall MDA and required metadata for efficient search and

Improving the Navys Passive Underwater Acoustic Monitoring of Marine Mammal Populations

DTIC Science & Technology

2015-09-30

DISTRIBUTION STATEMENT A: Distribution approved for public release; distribution is unlimited. Improving the Navy’s Passive Underwater Acoustic...mpl.ucsd.edu LONG-TERM GOALS The long-term goals of this research effort are to improve the Navy’s passive underwater acoustic monitoring of marine...research of a graduate student in marine bioacoustics and ocean acoustics at the Scripps Institution of Oceanography. OBJECTIVES The

On the Probability of Error and Stochastic Resonance in Discrete Memoryless Channels

DTIC Science & Technology

2013-12-01

Information - Driven Doppler Shift Estimation and Compensation Methods for Underwater Wireless Sensor Networks ”, which is to analyze and develop... underwater wireless sensor networks . We formulated an analytic relationship that relates the average probability of error to the systems parameters, the...thesis, we studied the performance of Discrete Memoryless Channels (DMC), arising in the context of cooperative underwater wireless sensor networks

Optical Magnetometry for Detecting Underwater Objects

DTIC Science & Technology

2015-09-21

underwater object. The two mechanisms responsible for the polarization rotation are the Surface Magneto-Optical Kerr Effect (SMOKE) and the Faraday effect...the underwater object itself ( Faraday effect). An analytical expression is obtained for the polarization-rotated field when the incident plane wave...Washington, DC 20375-5320 October 2014 – August 2015 NRL *University of Maryland, College Park, MD 20742-4111 Faraday SMOKE 67-4374-C4 1 Optical

Kinematical Comparison of the 200 m Backstroke Turns between National and Regional Level Swimmers

PubMed Central

Veiga, Santiago; Cala, Antonio; Frutos, Pablo González; Navarro, Enrique

2013-01-01

The aims of this investigation were to determine the evolution of selected turn variables during competitive backstroke races and to compare these kinematic variables between two different levels of swimmers. Sixteen national and regional level male swimmers participant in the 200 m backstroke event at the Spanish Swimming Championships in short course (25 m) were selected to analyze their turn performances. The individual distances method with two-dimensional Direct Linear Transformation (2D-DLT) algorithms was used to perform race analyses. National level swimmers presented a shorter “turn time”, a longer “distance in”, a faster “underwater velocity” and “normalized underwater velocity”, and a faster “stroking velocity” than regional level swimmers, whereas no significant differences were detected between levels for the “underwater distance”. National level swimmers maintained similar “turn times” over the event and increased “underwater velocity” and “normalized underwater velocity” in the last (seventh) turn segment, whereas regional level swimmers increased “turn time” in the last half of the race. For both national and regional level swimmers, turn “underwater distance” during the last three turns of the race was significantly shorter while no significant differences in distance into the wall occurred throughout the race. The skill level of the swimmers has an impact on the competitive backstroke turn segments. In a 200 m event, the underwater velocity should be maximized to maintain turn proficiency, whereas turn distance must be subordinated to the average velocity. Key Points The underwater turn velocity is as a critical variable related to the swimmers’ level of skill in a 200 m backstroke event. Best swimmers perform faster but no longer turn segments during a 200 m backstroke event. Best swimmers maintain their turn performance throughout the 200 m backstroke event by increasing the underwater velocity during the final part of the race. The turn distance out seems to be subordinated in order to maximize the average velocity during a 200 m backstroke event. PMID:24421733

Single particle fluorescence: a simple experimental approach to evaluate coincidence effects.

PubMed

Wu, Xihong; Omenetto, Nicoló; Smith, Benjamin W; Winefordner, James D

2007-07-01

Real-time characterization of the chemical and physical properties of individual aerosol particles is an important issue in environmental studies. A well-established way of accomplishing this task relies on the use of laser-induced fluorescence or laser ionization mass spectrometry. We describe here a simple approach aimed at experimentally verifying that single particles are indeed addressed. The approach has been tested with a system consisting of a series of aerodynamic lenses to form a beam of dye-doped particles aerosolized from a solution of known concentration with a medical nebulizer. Two independent spectral detection channels simultaneously measure the fluorescence signals generated in two different spectral regions by the passage of a mixture of two dye-doped particles through a focused laser beam in a vacuum chamber. Coincidence effects, arising from the simultaneous observation of both fluorescence emissions, can then be directly observed. Both dual-color fluorescence and pulse height distribution have been analyzed. As expected, the probability of single- or multiple-particle interaction strongly depends on the particle flux in the chamber, which is related to the concentration of particles in the nebulized solution. In our case, to achieve a two-particle coincidence smaller than 10%, a particle concentration lower than 1.2x10(5) particles/mL is required. Moreover, it was found that the experimental observations are in agreement with a simple mathematical model based on Poisson statistics. Although the results obtained refer to particle concentrations in solution, our approach can equally be applicable to experiments involving direct air sampling, provided that the number density of particles in air can be measured a priori, e.g., with a particle counter.

In situ measurements of desert dust particles above the western Mediterranean Sea with the balloon-borne Light Optical Aerosol Counter/sizer (LOAC) during the ChArMEx campaign of summer 2013

NASA Astrophysics Data System (ADS)

Renard, Jean-Baptiste; Dulac, François; Durand, Pierre; Bourgeois, Quentin; Denjean, Cyrielle; Vignelles, Damien; Couté, Benoit; Jeannot, Matthieu; Verdier, Nicolas; Mallet, Marc

2018-03-01

Mineral dust from arid areas is a major component of global aerosol and has strong interactions with climate and biogeochemistry. As part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx) to investigate atmospheric chemistry and its impacts in the Mediterranean region, an intensive field campaign was performed from mid-June to early August 2013 in the western basin including in situ balloon-borne aerosol measurements with the light optical aerosol counter (LOAC). LOAC is a counter/sizer that provides the aerosol concentrations in 19 size classes between 0.2 and 100 µm, and an indication of the nature of the particles based on dual-angle scattering measurements. A total of 27 LOAC flights were conducted mainly from Minorca Island (Balearic Islands, Spain) but also from Ile du Levant off Hyères city (SE France) under 17 light dilatable balloons (meteorological sounding balloons) and 10 boundary layer pressurised balloons (quasi-Lagrangian balloons). The purpose was to document the vertical extent of the plume and the time evolution of the concentrations at constant altitude (air density) by in situ observations. LOAC measurements are in agreement with ground-based measurements (lidar, photometer), aircraft measurements (counters), and satellite measurements (CALIOP) in the case of fair spatial and temporal coincidences. LOAC has often detected three modes in the dust particle volume size distributions fitted by lognormal laws at roughly 0.2, 4 and 30 µm in modal diameter. Thanks to the high sensitivity of LOAC, particles larger than 40 µm were observed, with concentrations up to about 10-4 cm-3. Such large particles were lifted several days before and their persistence after transport over long distances is in conflict with calculations of dust sedimentation. We did not observe any significant evolution of the size distribution during the transport from quasi-Lagrangian flights, even for the longest ones ( ˜ 1 day). Finally, the presence of charged particles is inferred from the LOAC measurements and we speculate that electrical forces might counteract gravitational settling of the coarse particles.

Underwater video enhancement using multi-camera super-resolution

NASA Astrophysics Data System (ADS)

Quevedo, E.; Delory, E.; Callicó, G. M.; Tobajas, F.; Sarmiento, R.

2017-12-01

Image spatial resolution is critical in several fields such as medicine, communications or satellite, and underwater applications. While a large variety of techniques for image restoration and enhancement has been proposed in the literature, this paper focuses on a novel Super-Resolution fusion algorithm based on a Multi-Camera environment that permits to enhance the quality of underwater video sequences without significantly increasing computation. In order to compare the quality enhancement, two objective quality metrics have been used: PSNR (Peak Signal-to-Noise Ratio) and the SSIM (Structural SIMilarity) index. Results have shown that the proposed method enhances the objective quality of several underwater sequences, avoiding the appearance of undesirable artifacts, with respect to basic fusion Super-Resolution algorithms.

Robust automatic control system of vessel descent-rise device for plant with distributed parameters “cable – towed underwater vehicle”

NASA Astrophysics Data System (ADS)

Chupina, K. V.; Kataev, E. V.; Khannanov, A. M.; Korshunov, V. N.; Sennikov, I. A.

2018-05-01

The paper is devoted to a problem of synthesis of the robust control system for a distributed parameters plant. The vessel descent-rise device has a heave compensation function for stabilization of the towed underwater vehicle on a set depth. A sea state code, parameters of the underwater vehicle and cable vary during underwater operations, the vessel heave is a stochastic process. It means that the plant and external disturbances have uncertainty. That is why it is necessary to use the robust theory for synthesis of an automatic control system, but without use of traditional methods of optimization, because this cable has distributed parameters. The offered technique has allowed one to design an effective control system for stabilization of immersion depth of the towed underwater vehicle for various degrees of sea roughness and to provide its robustness to deviations of parameters of the vehicle and cable’s length.

Aquatic Acoustic Metrics Interface

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

2012-12-18

Fishes and marine mammals may suffer a range of potential effects from exposure to intense underwater sound generated by anthropogenic activities such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording (USR) devices have been built to acquire samples of the underwater sound generated by anthropogenic activities. Software becomes indispensable for processing and analyzing the audio files recorded by these USRs. The new Aquatic Acoustic Metrics Interface Utility Software (AAMI) is specifically designed for analysis of underwater sound recordings to provide data in metrics that facilitate evaluation of the potential impacts of the sound on aquatic animals.more » In addition to the basic functions, such as loading and editing audio files recorded by USRs and batch processing of sound files, the software utilizes recording system calibration data to compute important parameters in physical units. The software also facilitates comparison of the noise sound sample metrics with biological measures such as audiograms of the sensitivity of aquatic animals to the sound, integrating various components into a single analytical frame.« less

Object detection from images obtained through underwater turbulence medium

NASA Astrophysics Data System (ADS)

Furhad, Md. Hasan; Tahtali, Murat; Lambert, Andrew

2017-09-01

Imaging through underwater experiences severe distortions due to random fluctuations of temperature and salinity in water, which produces underwater turbulence through diffraction limited blur. Lights reflecting from objects perturb and attenuate contrast, making the recognition of objects of interest difficult. Thus, the information available for detecting underwater objects of interest becomes a challenging task as they have inherent confusion among the background, foreground and other image properties. In this paper, a saliency-based approach is proposed to detect the objects acquired through an underwater turbulent medium. This approach has drawn attention among a wide range of computer vision applications, such as image retrieval, artificial intelligence, neuro-imaging and object detection. The image is first processed through a deblurring filter. Next, a saliency technique is used on the image for object detection. In this step, a saliency map that highlights the target regions is generated and then a graph-based model is proposed to extract these target regions for object detection.

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.

Underwater binocular imaging of aerial objects versus the position of eyes relative to the flat water surface.

PubMed

Barta, András; Horváth, Gábor

2003-12-01

The apparent position, size, and shape of aerial objects viewed binocularly from water change as a result of the refraction of light at the water surface. Earlier studies of the refraction-distorted structure of the aerial binocular visual field of underwater observers were restricted to either vertically or horizontally oriented eyes. Here we calculate the position of the binocular image point of an aerial object point viewed by two arbitrarily positioned underwater eyes when the water surface is flat. Assuming that binocular image fusion is performed by appropriate vergent eye movements to bring the object's image onto the foveae, the structure of the aerial binocular visual field is computed and visualized as a function of the relative positions of the eyes. We also analyze two erroneous representations of the underwater imaging of aerial objects that have occurred in the literature. It is demonstrated that the structure of the aerial binocular visual field of underwater observers distorted by refraction is more complex than has been thought previously.

Induction of settlement in mussel (Perna canaliculus) larvae by vessel noise.

PubMed

Wilkens, S L; Stanley, J A; Jeffs, A G

2012-01-01

Underwater sound plays an important role in the settlement behaviour of many coastal organisms. Large steel-hulled vessels are known to be a major source of underwater sound in the marine environment. The possibility that underwater sound from vessels may promote biofouling of hulls through triggering natural larval settlement cues was investigated for the mussel, Perna canaliculus. The mussel larvae showed significantly faster settlement when exposed to the underwater noise produced by a 125-m long steel-hulled passenger and freight ferry. Median time to attachment on the substrata (ie settlement) was reduced by 22% and the time taken for all experimental larvae to settle was reduced by 40% relative to a silent control. There was no difference in the survival of the mussel larvae among the various noise treatments. The decrease in settlement time of the mussel larvae appeared to correlate with the intensity of the vessel sound, suggesting that underwater sound emanating from vessels may be an important factor in exacerbating hull fouling by mussels.

Development of hybrid method for the prediction of underwater propeller noise

NASA Astrophysics Data System (ADS)

Seol, Hanshin; Suh, Jung-Chun; Lee, Soogab

2005-11-01

Noise reduction and control is an important problem in the performance of underwater acoustic systems and in the habitability of the passenger ship for crew and passenger. Furthermore, sound generated by a propeller is critical in underwater detection and it is often related to the survivability of the vessel especially for military purpose. This paper presents a numerical study on the non-cavitating and blade sheet cavitation noises of the underwater propeller. A brief summary of numerical method with verification and results are presented. The noise is predicted using time-domain acoustic analogy. The flow field is analyzed with potential-based panel method, and then the time-dependent pressure and sheet cavity volume data are used as the input for Ffowcs Williams-Hawkings formulation to predict the far-field acoustics. Noise characteristics are presented according to noise sources and conditions. Through this study, the dominant noise source of the underwater propeller is analyzed, which will provide a basis for proper noise control strategies.

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.

Modelling of depth stabilization and submerging of tethered underwater garage in conditions of sea oscillating motion

NASA Astrophysics Data System (ADS)

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

2018-03-01

The paper is dedicated to examining dynamics of a submersible underwater garage in conditions of significant sea oscillation. During the considered research, the mathematical model of the electromechanical depth control system, considering interval parametric uncertainty of the system and distribution of tether mass, was developed. An influence of sea oscillation on submerging underwater garages and their depth stabilization processes was analyzed.

Development of a Long-Range Gliding Underwater Vehicle Utilizing Java Sun SPOT Technology

DTIC Science & Technology

2008-09-01

release; distribution is unlimited DEVELOPMENT OF A LONG-RANGE GLIDING UNMANNED UNDERWATER VEHICLE UTILIZING JAVA SUN SPOT TECHNOLOGY by...TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE: Development of a Long-Range Gliding Underwater Vehicle Utilizing Java Sun SPOT...vehicle. Further work is needed to demonstrate the efficiency and effectiveness of this design. 15. NUMBER OF PAGES 117 14. SUBJECT TERMS Java

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

An Evaluation of Potential Operating Systems for Autonomous Underwater Vehicles

DTIC Science & Technology

2013-02-01

Remotely Operated Vehicle RTOS Real-Time Operating System SAUC -E Student Autonomous Underwater Vehicle Challenge - Europe TCP Transmission Control Protocol...popularity, with examples including the Student Autonomous Underwater Vehicle Challenge - Europe ( SAUC -E) [7] and the AUVSI robosub competition [8]. For...28] for entry into AUV competitions such as SAUC -E [7], and AUVSI [8]. 8 UNCLASSIFIED UNCLASSIFIED DSTO–TN–1194 3.4 Windows CE Windows CE

Quantifying the Effects of Propagation on Classification of Cetacean Vocalizations

DTIC Science & Technology

2015-09-30

mammals can be found in all ocean basins, their habitats cover diverse underwater environments. It is well known that acoustic propagation can vary...propagation on an automated classifier, using both underwater propagation experiments and complementary modeling. If propagation does impact some... Underwater Sound, 3rd ed., McGraw-Hill Book Company, 1983. [2] F. B. Jensen, W. A. Kuperman, M.B. Porter, and H. Schmidt, Computational Ocean Acoustics

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

CFD Based Added Mass Prediction in Cruise Condition of Underwater Vehicle Dynamic

NASA Astrophysics Data System (ADS)

Agoes Moelyadi, Mochammad; Bambang Riswandi, Bagus

2018-04-01

One of the unsteady flow behavior on the hydrodynamic characteristics of underwater vehicle is the presence of added mass. In cruising conditions, the underwater vehicle may require the addition of speed or experience the disturbance in the form of unsteady flow so that cause the hydrodynamic interaction between the surface of the vehicle with the surrounding fluid. This leads to the rise of local velocity of flow and the great changes of hydrodynamic forces which are very influential on the stability of the underwater vehicle. One of the result is an additional force called added mass. It is very useful parameter to control underwater vehicle dynamic.This paper reports the research on the added mass coefficient of underwater vehicles obtained through the Computational Fluid Dynmaic (CFD) simulation method using CFX software. Added mass coefficient is calculated by performing an unsteady simulation or known as transient simulation. Computational simulations are based on the Reynold Average Navier- Stokes (RANS) equation solution. The simulated vehicle moves forward and backward according to the sinus function, with a frequency of 0.25 Hz, a 2 m amplitude, a cruising depth of 10 m below sea level, and Vcruise 1.54 m / s (Re = 9.000.000). Simulation result data includes velocity contour, variation of force and acceleration to frequency, and added mass coefficient.

Superior underwater vision in a human population of sea gypsies.

PubMed

Gislén, Anna; Dacke, Marie; Kröger, Ronald H H; Abrahamsson, Maths; Nilsson, Dan-Eric; Warrant, Eric J

2003-05-13

Humans are poorly adapted for underwater vision. In air, the curved corneal surface accounts for two-thirds of the eye's refractive power, and this is lost when air is replaced by water. Despite this, some tribes of sea gypsies in Southeast Asia live off the sea, and the children collect food from the sea floor without the use of visual aids. This is a remarkable feat when one considers that the human eye is not focused underwater and small objects should remain unresolved. We have measured the visual acuity of children in a sea gypsy population, the Moken, and found that the children see much better underwater than one might expect. Their underwater acuity (6.06 cycles/degree) is more than twice as good as that of European children (2.95 cycles/degree). Our investigations show that the Moken children achieve their superior underwater vision by maximally constricting the pupil (1.96 mm compared to 2.50 mm in European children) and by accommodating to the known limit of human performance (15-16 D). This extreme reaction-which is routine in Moken children-is completely absent in European children. Because they are completely dependent on the sea, the Moken are very likely to derive great benefit from this strategy.

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

Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization.

PubMed

Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y; Alouini, Mohamed-Slim

2017-12-26

Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique.

Gas film retention and underwater photosynthesis during field submergence of four contrasting rice genotypes

PubMed Central

Winkel, Anders; Pedersen, Ole; Ella, Evangelina; Ismail, Abdelbagi M.; Colmer, Timothy D.

2014-01-01

Floods can completely submerge some rice (Oryza sativa L.) fields. Leaves of rice have gas films that aid O2 and CO2 exchange under water. The present study explored the relationship between gas film persistence and underwater net photosynthesis (PN) as influenced by genotype and submergence duration. Four contrasting genotypes (FR13A, IR42, Swarna, and Swarna-Sub1) were submerged for 13 days in the field and leaf gas films, chlorophyll, and the capacity for underwater PN at near ambient and high CO2 were assessed with time of submergence. At high CO2 during the PN assay, all genotypes initially showed high rates of underwater PN, and this rate was not affected by time of submergence in FR13A. This superior photosynthetic performance of FR13A was not evident in Swarna-Sub1 (carrying the SUB1 QTL) and the declines in underwater PN in both Swarna-Sub1 and Swarna were equal to that in IR42. At near ambient CO2 concentration, underwater PN declined in all four genotypes and this corresponded with loss of leaf gas films with time of submergence. FR13A retained leaf gas films moderately longer than the other genotypes, but gas film retention was not linked to SUB1. Diverse rice germplasm should be screened for gas film persistence during submergence, as this trait could potentially increase carbohydrate status and internal aeration owing to increased underwater PN, which contributes to submergence tolerance in rice. PMID:24759881

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.

The key kinematic determinants of undulatory underwater swimming at maximal velocity.

PubMed

Connaboy, Chris; Naemi, Roozbeh; Brown, Susan; Psycharakis, Stelios; McCabe, Carla; Coleman, Simon; Sanders, Ross

2016-01-01

The optimisation of undulatory underwater swimming is highly important in competitive swimming performance. Nineteen kinematic variables were identified from previous research undertaken to assess undulatory underwater swimming performance. The purpose of the present study was to determine which kinematic variables were key to the production of maximal undulatory underwater swimming velocity. Kinematic data at maximal undulatory underwater swimming velocity were collected from 17 skilled swimmers. A series of separate backward-elimination analysis of covariance models was produced with cycle frequency and cycle length as dependent variables (DVs) and participant as a fixed factor, as including cycle frequency and cycle length would explain 100% of the maximal swimming velocity variance. The covariates identified in the cycle-frequency and cycle-length models were used to form the saturated model for maximal swimming velocity. The final parsimonious model identified three covariates (maximal knee joint angular velocity, maximal ankle angular velocity and knee range of movement) as determinants of the variance in maximal swimming velocity (adjusted-r2 = 0.929). However, when participant was removed as a fixed factor there was a large reduction in explained variance (adjusted r2 = 0.397) and only maximal knee joint angular velocity continued to contribute significantly, highlighting its importance to the production of maximal swimming velocity. The reduction in explained variance suggests an emphasis on inter-individual differences in undulatory underwater swimming technique and/or anthropometry. Future research should examine the efficacy of other anthropometric, kinematic and coordination variables to better understand the production of maximal swimming velocity and consider the importance of individual undulatory underwater swimming techniques when interpreting the data.

Gas film retention and underwater photosynthesis during field submergence of four contrasting rice genotypes.

PubMed

Winkel, Anders; Pedersen, Ole; Ella, Evangelina; Ismail, Abdelbagi M; Colmer, Timothy D

2014-07-01

Floods can completely submerge some rice (Oryza sativa L.) fields. Leaves of rice have gas films that aid O2 and CO2 exchange under water. The present study explored the relationship between gas film persistence and underwater net photosynthesis (PN) as influenced by genotype and submergence duration. Four contrasting genotypes (FR13A, IR42, Swarna, and Swarna-Sub1) were submerged for 13 days in the field and leaf gas films, chlorophyll, and the capacity for underwater PN at near ambient and high CO2 were assessed with time of submergence. At high CO2 during the PN assay, all genotypes initially showed high rates of underwater PN, and this rate was not affected by time of submergence in FR13A. This superior photosynthetic performance of FR13A was not evident in Swarna-Sub1 (carrying the SUB1 QTL) and the declines in underwater PN in both Swarna-Sub1 and Swarna were equal to that in IR42. At near ambient CO2 concentration, underwater PN declined in all four genotypes and this corresponded with loss of leaf gas films with time of submergence. FR13A retained leaf gas films moderately longer than the other genotypes, but gas film retention was not linked to SUB1. Diverse rice germplasm should be screened for gas film persistence during submergence, as this trait could potentially increase carbohydrate status and internal aeration owing to increased underwater PN, which contributes to submergence tolerance in rice. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Roles of individual radicals generated by a submerged dielectric barrier discharge plasma reactor during Escherichia coli O157:H7 inactivation

NASA Astrophysics Data System (ADS)

Khan, Muhammad Saiful Islam; Lee, Eun-Jung; Kim, Yun-Ji

2015-10-01

A submerged dielectric barrier discharge plasma reactor (underwater DBD) has been used on Escherichia coli O157:H7 (ATCC 35150). Plasma treatment was carried out using clean dry air gas to investigate the individual effects of the radicals produced by underwater DBD on an E. coli O157:H7 suspension (8.0 log CFU/ml). E. coli O157:H7 was reduced by 6.0 log CFU/ml for 2 min of underwater DBD plasma treatment. Optical Emission Spectra (OES) shows that OH and NO (α, β) radicals, generated by underwater DBD along with ozone gas. E. coli O157:H7 were reduced by 2.3 log CFU/ml for 10 min of underwater DBD plasma treatment with the terephthalic acid (TA) OH radical scavenger solution, which is significantly lower (3.7 log CFU/ml) than the result obtained without using the OH radical scavenger. A maximum of 1.5 ppm of ozone gas was produced during the discharge of underwater DBD, and the obtained reduction difference in E.coli O157:H7 in presence and in absence of ozone gas was 1.68 log CFU/ml. The remainder of the 0.62 log CFU/ml reduction might be due to the effect of the NO (α, β) radicals or due to the combined effect of all the radicals produced by underwater DBD. A small amount of hydrogen peroxide was also generated but does not play any role in E. coli O157:H7 inactivation.

Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization

PubMed Central

Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2017-01-01

Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique. PMID:29278405

A Probabilistic and Highly Efficient Topology Control Algorithm for Underwater Cooperating AUV Networks

PubMed Central

Li, Ning; Cürüklü, Baran; Bastos, Joaquim; Sucasas, Victor; Fernandez, Jose Antonio Sanchez; Rodriguez, Jonathan

2017-01-01

The aim of the Smart and Networking Underwater Robots in Cooperation Meshes (SWARMs) project is to make autonomous underwater vehicles (AUVs), remote operated vehicles (ROVs) and unmanned surface vehicles (USVs) more accessible and useful. To achieve cooperation and communication between different AUVs, these must be able to exchange messages, so an efficient and reliable communication network is necessary for SWARMs. In order to provide an efficient and reliable communication network for mission execution, one of the important and necessary issues is the topology control of the network of AUVs that are cooperating underwater. However, due to the specific properties of an underwater AUV cooperation network, such as the high mobility of AUVs, large transmission delays, low bandwidth, etc., the traditional topology control algorithms primarily designed for terrestrial wireless sensor networks cannot be used directly in the underwater environment. Moreover, these algorithms, in which the nodes adjust their transmission power once the current transmission power does not equal an optimal one, are costly in an underwater cooperating AUV network. Considering these facts, in this paper, we propose a Probabilistic Topology Control (PTC) algorithm for an underwater cooperating AUV network. In PTC, when the transmission power of an AUV is not equal to the optimal transmission power, then whether the transmission power needs to be adjusted or not will be determined based on the AUV’s parameters. Each AUV determines their own transmission power adjustment probability based on the parameter deviations. The larger the deviation, the higher the transmission power adjustment probability is, and vice versa. For evaluating the performance of PTC, we combine the PTC algorithm with the Fuzzy logic Topology Control (FTC) algorithm and compare the performance of these two algorithms. The simulation results have demonstrated that the PTC is efficient at reducing the transmission power adjustment ratio while improving the network performance. PMID:28471387

A Probabilistic and Highly Efficient Topology Control Algorithm for Underwater Cooperating AUV Networks.

PubMed

Li, Ning; Cürüklü, Baran; Bastos, Joaquim; Sucasas, Victor; Fernandez, Jose Antonio Sanchez; Rodriguez, Jonathan

2017-05-04

The aim of the Smart and Networking Underwater Robots in Cooperation Meshes (SWARMs) project is to make autonomous underwater vehicles (AUVs), remote operated vehicles (ROVs) and unmanned surface vehicles (USVs) more accessible and useful. To achieve cooperation and communication between different AUVs, these must be able to exchange messages, so an efficient and reliable communication network is necessary for SWARMs. In order to provide an efficient and reliable communication network for mission execution, one of the important and necessary issues is the topology control of the network of AUVs that are cooperating underwater. However, due to the specific properties of an underwater AUV cooperation network, such as the high mobility of AUVs, large transmission delays, low bandwidth, etc., the traditional topology control algorithms primarily designed for terrestrial wireless sensor networks cannot be used directly in the underwater environment. Moreover, these algorithms, in which the nodes adjust their transmission power once the current transmission power does not equal an optimal one, are costly in an underwater cooperating AUV network. Considering these facts, in this paper, we propose a Probabilistic Topology Control (PTC) algorithm for an underwater cooperating AUV network. In PTC, when the transmission power of an AUV is not equal to the optimal transmission power, then whether the transmission power needs to be adjusted or not will be determined based on the AUV's parameters. Each AUV determines their own transmission power adjustment probability based on the parameter deviations. The larger the deviation, the higher the transmission power adjustment probability is, and vice versa. For evaluating the performance of PTC, we combine the PTC algorithm with the Fuzzy logic Topology Control (FTC) algorithm and compare the performance of these two algorithms. The simulation results have demonstrated that the PTC is efficient at reducing the transmission power adjustment ratio while improving the network performance.

OceanVideoLab: A Tool for Exploring Underwater Video

NASA Astrophysics Data System (ADS)

Ferrini, V. L.; Morton, J. J.; Wiener, C.

2016-02-01

Video imagery acquired with underwater vehicles is an essential tool for characterizing seafloor ecosystems and seafloor geology. It is a fundamental component of ocean exploration that facilitates real-time operations, augments multidisciplinary scientific research, and holds tremendous potential for public outreach and engagement. Acquiring, documenting, managing, preserving and providing access to large volumes of video acquired with underwater vehicles presents a variety of data stewardship challenges to the oceanographic community. As a result, only a fraction of underwater video content collected with research submersibles is documented, discoverable and/or viewable online. With more than 1 billion users, YouTube offers infrastructure that can be leveraged to help address some of the challenges associated with sharing underwater video with a broad global audience. Anyone can post content to YouTube, and some oceanographic organizations, such as the Schmidt Ocean Institute, have begun live-streaming video directly from underwater vehicles. OceanVideoLab (oceanvideolab.org) was developed to help improve access to underwater video through simple annotation, browse functionality, and integration with related environmental data. Any underwater video that is publicly accessible on YouTube can be registered with OceanVideoLab by simply providing a URL. It is strongly recommended that a navigational file also be supplied to enable geo-referencing of observations. Once a video is registered, it can be viewed and annotated using a simple user interface that integrates observations with vehicle navigation data if provided. This interface includes an interactive map and a list of previous annotations that allows users to jump to times of specific observations in the video. Future enhancements to OceanVideoLab will include the deployment of a search interface, the development of an application program interface (API) that will drive the search and enable querying of content by other systems/tools, the integration of related environmental data from complementary data systems (e.g. temperature, bathymetry), and the expansion of infrastructure to enable broad crowdsourcing of annotations.

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.

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

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

ROVs in a Bucket: Contagious, Experiential Learning by Building Inexpensive, Underwater Robots

DTIC Science & Technology

2007-01-01

R., “Toward an applied theory of experiential learning ,” in C. Cooper (ed.) Theories of Group Process, London: John Wiley. (1975) [8] C. Beard, JP...ROVs in a Bucket” Contagious, Experiential Learning by Building Inexpensive, Underwater Robots Douglas R. Levin Krista Trono Christine...Contagious, Experiential Learning by Building Inexpensive, Underwater Robots 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

Extending The Calibration In The Underwater Sound Reference Division (USRD) Reciprocity Coupler To Incorporate Phase

DTIC Science & Technology

2016-09-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS EXTENDING THE CALIBRATION IN THE UNDERWATER SOUND REFERENCE DIVISION (USRD) RECIPROCITY COUPLER...AND DATES COVERED Master’s Thesis 08-01-2014 to 08-21-2016 4. TITLE AND SUBTITLE EXTENDING THE CALIBRATION IN THE UNDERWATER SOUND REFERENCE DIVISION...SPONSORING / MONITORING AGENCY REPORT NUMBER 11. SUPPLEMENTARY NOTES The views expressed in this document are those of the author and do not reflect

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.

Underwater electric field detection system based on weakly electric fish

NASA Astrophysics Data System (ADS)

Xue, Wei; Wang, Tianyu; Wang, Qi

2018-04-01

Weakly electric fish sense their surroundings in complete darkness by their active electric field detection system. However, due to the insufficient detection capacity of the electric field, the detection distance is not enough, and the detection accuracy is not high. In this paper, a method of underwater detection based on rotating current field theory is proposed to improve the performance of underwater electric field detection system. First of all, we built underwater detection system based on the theory of the spin current field mathematical model with the help of the results of previous researchers. Then we completed the principle prototype and finished the metal objects in the water environment detection experiments, laid the foundation for the further experiments.

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

Magnetic gradiometer for underwater detection applications

NASA Astrophysics Data System (ADS)

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

2006-05-01

We have designed and constructed a magnetic gradiometer for underwater mine detection, location and tracking. The United States Naval Surface Warfare Center (NSWC PC) in Panama City, FL has conducted sea tests of the system using an unmanned underwater vehicle (UUV). The Real-Time Tracking Gradiometer (RTG) measures the magnetic field gradients caused by the presence of a mine in the Earth's magnetic field. These magnetic gradients can then be used to detect and locate a target with the UUV in motion. Such a platform can also be used for other applications, including the detection and tracking of vessels and divers for homeland (e.g., port) security and the detection of underwater pipelines. Data acquired by the RTG in sea tests is presented in this paper.

Study of opto-acoustic communication between air and underwater carrier

NASA Astrophysics Data System (ADS)

Zong, Si-Guang; Liu, Tao; Cao, Jing; He, Qi-Yi

2018-02-01

How to solve the communication problem to the underwater target has turned into one of the subjects that the militarists of all over the world commonly concern. Laser-induced acoustic signal is a new approach for underwater acoustic source, which has much virtue such as high intensity, short pulse and broad frequency. The paper studies the opto-acoustic communication method. The acoustic signal characteristic of laser-induced breakdown is studied and corresponding theory model is systemically analyzed. The opto-acoustic communication experimental measure investigation is formed with the high power laser, water tank and high frequency hydrophone. The characteristic of acoustic signal is analyzed, such as intensity and frequency. This makes a stride for pursing the feasibility of laser-acoustic underwater communication.

A Network Coding Based Hybrid ARQ Protocol for Underwater Acoustic Sensor Networks

PubMed Central

Wang, Hao; Wang, Shilian; Zhang, Eryang; Zou, Jianbin

2016-01-01

Underwater Acoustic Sensor Networks (UASNs) have attracted increasing interest in recent years due to their extensive commercial and military applications. However, the harsh underwater channel causes many challenges for the design of reliable underwater data transport protocol. In this paper, we propose an energy efficient data transport protocol based on network coding and hybrid automatic repeat request (NCHARQ) to ensure reliability, efficiency and availability in UASNs. Moreover, an adaptive window length estimation algorithm is designed to optimize the throughput and energy consumption tradeoff. The algorithm can adaptively change the code rate and can be insensitive to the environment change. Extensive simulations and analysis show that NCHARQ significantly reduces energy consumption with short end-to-end delay. PMID:27618044

REGRESSION ANALYSIS OF SEA-SURFACE-TEMPERATURE PATTERNS FOR THE NORTH PACIFIC OCEAN.

DTIC Science & Technology

SEA WATER, *SURFACE TEMPERATURE, *OCEANOGRAPHIC DATA, PACIFIC OCEAN, REGRESSION ANALYSIS , STATISTICAL ANALYSIS, UNDERWATER EQUIPMENT, DETECTION, UNDERWATER COMMUNICATIONS, DISTRIBUTION, THERMAL PROPERTIES, COMPUTERS.

pH-Manipulated Underwater-Oil Adhesion Wettability Behavior on the Micro/Nanoscale Semicircular Structure and Related Thermodynamic Analysis.

PubMed

Tie, Lu; Guo, Zhiguang; Liu, Weimin

2015-05-20

Controlling oil of wettability behavior in response to the underwater out stimulation has shown promising applications in understanding and designing novel micro- or nanofluidic devices. In this article, the pH-manipulated underwater-oil adhesion wetting phenomenon and superoleophobicity on the micro- and nanotexture copper mesh films (CMF) were investigated. It should be noted that the surface exhibits underwater superoleophobicity under different pH values of the solution; however, the underwater-oil adhesion behavior on the surface is dramatically influenced by the pH value of the solution. On the basis of the thermodynamic analysis, a plausible mechanism to explain the pH-controllable underwater-oil adhesion and superoleophobic wetting behavior observed on a micro- and nanoscale semicircular structure has been revealed. Furthermore, variation of chemistry (intrinsic oil contact angle (OCA)) of the responsive surface that due to the carboxylic acid groups is protonated or deprotonated by the acidic or basic solution on free energy (FE) with its barrier (FEB) and equilibrium oil contact angle (EOCA) with it hysteresis (OCAH) are discussed. The result shows that a critical intrinsic OCA on the micro- and nano- semicircular texture is necessary for conversion from the oil Cassie impregnating to oil Cassie wetting state. In a water/oil/solid system, the mechanism reveals that the differences between the underwater OCA and oil adhesive force of the responsive copper mesh film under different pH values of solution are ascribed to the different oil wetting state that results from combining the changing intrinsic OCA and micro-/nanosemicircular structures. These results are well in agreement with the experiment.

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.

Underwater disorientation as induced by two helicopter ditching devices.

PubMed

Cheung, B; Hofer, K; Brooks, C J; Gibbs, P

2000-09-01

Spatial orientation is based on the integration of concordant and redundant information from the visual, vestibular, and somatosensory systems. When a person is submerged underwater, somatosensory cues are reduced, and vestibular cues are ambiguous with respect to upright or inverted position. Visual cues may be lost as a result of reduced ambient light. Underwater disorientation has been cited as one of the major factors that could inhibit emergency egress after a helicopter ditching into water. One countermeasure to familiarize aircrew with underwater disorientation is emergency egress training. This study examined the relative degree of underwater disorientation induced by the Modular Egress Training Simulator (METS) and the Shallow Water Egress Trainer (SWET). There were 36 healthy subjects (28 males and 8 females) who participated in the study. Underwater disorientation was quantified by measuring the deviation of subjective vertical-pointing from the gravitational vertical, time to egress, and subjective reports of disorientation and ease of egress. A repeated measure design was employed with seat position (SWET chair, METS window, and METS aisle) as the sole factor. Subjective response data indicated that the degree of disorientation is rated significantly higher, and the ease of egress is rated worse from the two METS seat positions than from the SWET. This is supported by the findings that subjective vertical-pointing accuracy is worse in the METS seat positions than in the SWET (p < 0.01). The time to egress is longer from the two METS seat positions than from SWET (p < 0.01). Our results indicate that the METS device is effective for inducing underwater disorientation as provoked by simulated helicopter ditching. disorientation, vestibular, subjective pointing.

Performance analysis of a multispectral framing camera for detecting mines in the littoral zone and beach zone

NASA Astrophysics Data System (ADS)

Louchard, Eric; Farm, Brian; Acker, Andrew

2008-04-01

BAE Systems Sensor Systems Identification & Surveillance (IS) has developed, under contract with the Office of Naval Research, a multispectral airborne sensor system and processing algorithms capable of detecting mine-like objects in the surf zone and land mines in the beach zone. BAE Systems has used this system in a blind test at a test range established by the Naval Surface Warfare Center - Panama City Division (NSWC-PCD) at Eglin Air Force Base. The airborne and ground subsystems used in this test are described, with graphical illustrations of the detection algorithms. We report on the performance of the system configured to operate with a human operator analyzing data on a ground station. A subsurface (underwater bottom proud mine in the surf zone and moored mine in shallow water) mine detection capability is demonstrated in the surf zone. Surface float detection and proud land mine detection capability is also demonstrated. Our analysis shows that this BAE Systems-developed multispectral airborne sensor provides a robust technical foundation for a viable system for mine counter-measures, and would be a valuable asset for use prior to an amphibious assault.

Flow analysis of new type propulsion system for UV’s

NASA Astrophysics Data System (ADS)

Eimanis, M.; Auzins, J.

2017-10-01

This paper presents an original design of an autonomous underwater vehicle where thrust force is created by the helicoidal shape of the hull rather than screw propellers. Propulsion force is created by counter-rotating bow and stern parts. The middle part of the vehicle has the function of a cargo compartment containing all control mechanisms and communications. It’s made of elastic material, containing a Cardan-joint mechanism, which allows changing the direction of vehicle, actuated by bending drives. A bending drive velocity control algorithm for the automatic control of vehicle movement direction is proposed. The dynamics of AUV are simulated using multibody simulation software MSC Adams. For the simulation of water resistance forces and torques the surrogate polynomial metamodels are created on the basis of computer experiments with CFD software. For flow interaction with model geometry the simplified vehicle model is submerged in fluid medium using special CFD software, with the same idea used in wind tunnel experiments. The simulation results are compared with measurements of the AUV prototype, created at Institute of Mechanics of Riga Technical University. Experiments with the prototype showed good agreement with simulation results and confirmed the effectiveness and the future potential of the proposed principle.

The Impact of Gate Width Setting and Gate Utilization Factors on Plutonium Assay in Passive Correlated Neutron Counting

DOE PAGES

Henzlova, Daniela; Menlove, Howard Olsen; Croft, Stephen; ...

2015-06-15

In the field of nuclear safeguards, passive neutron multiplicity counting (PNMC) is a method typically employed in non-destructive assay (NDA) of special nuclear material (SNM) for nonproliferation, verification and accountability purposes. PNMC is generally performed using a well-type thermal neutron counter and relies on the detection of correlated pairs or higher order multiplets of neutrons emitted by an assayed item. To assay SNM, a set of parameters for a given well-counter is required to link the measured multiplicity rates to the assayed item properties. Detection efficiency, die-away time, gate utilization factors (tightly connected to die-away time) as well as optimummore » gate width setting are among the key parameters. These parameters along with the underlying model assumptions directly affect the accuracy of the SNM assay. In this paper we examine the role of gate utilization factors and the single exponential die-away time assumption and their impact on the measurements for a range of plutonium materials. In addition, we examine the importance of item-optimized coincidence gate width setting as opposed to using a universal gate width value. Finally, the traditional PNMC based on multiplicity shift register electronics is extended to Feynman-type analysis and application of this approach to Pu mass assay is demonstrated.« less

Using marketing muscle to sell fat: the rise of obesity in the modern economy.

PubMed

Zimmerman, Frederick J

2011-01-01

The large increase in obesity in the past 30 years has often been explained in rational choice terms; for example, a decline in food prices has engendered greater food consumption. On closer examination, this kind of explanation does not fit the facts of the current obesity epidemic. Instead, an unprecedented expansion in the scope, power, and ubiquity of food marketing has coincided with an unprecedented expansion in food consumption in predictable ways. Ongoing protestations that the causes of the recent increase in obesity are unknown may overstate the case. Ample evidence indicates that the obesity epidemic is, at least to a large degree, the result of increased marketing power over the American diet. Only by reigning in or countering marketing power can rationality be restored to the dietary choices of Americans.

The X-ray morphology of the relaxed cluster of galaxies A2256. II - Sources around the extended cluster emission

NASA Technical Reports Server (NTRS)

Henry, J. P.; Briel, U. G.

1991-01-01

The X-ray observation of A2256 with the imaging proportional counter on board the X-ray observatory Rosat revealed significantly more sources in the field around the extended cluster emission than expected by chance. In a preliminary investigation, 14 sources were discovered at the limiting flux for this exposure whereas about 7 sources would have been expected by chance. At least two of those sources are coincident with cluster-member galaxies, having X-ray luminosities of approximately 10 to the 42nd erg/s in the Rosat energy band from 0.1 to 2.4 keV, but at least four more are from 'dark' objects. The similarity of these objects to those in A1367 suggests the existence of a new class of X-ray sources in clusters.

Effects of underwater escape training--a psychophysiological study.

PubMed

Hytten, K; Jensen, A; Vaernes, R

1989-05-01

The effect of underwater escape training was analysed among 78 participants at the Norwegian Underwater Technological Center (NUTEC), Bergen, in a psychophysiological study. The training caused significant physiological activation. Perceived training effect was found to be inversely related to anxiety during training. Most of the participants developed a positive response outcome expectancy and increased confidence in flying. The learning aspects were versatile and partly dependent on personality factors. A more individualized approach to training is recommended.

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

DTIC Science & Technology

1998-03-01

34Numerical Recipes in C," second edition, Cambridge University Press, Cambridge England, 1992. Marco, David , "Autonomous Control of Underwater...in the viewer. -202- LIST OF REFERENCES Ames, Andrea L., Nadeau, David R., Moreland, John L., VRML 2.0 Sourcebook, Second edition, John Wiley...McGhee, Bob, "The Phoenix Autonomous Underwater Vehicle," AI-Based Mobile Robots, editors David Kortenkamp, Pete Bonasso and Robin Murphy, MJT/AAAI

Selection of the most influential factors on the water-jet assisted underwater laser process by adaptive neuro-fuzzy technique

NASA Astrophysics Data System (ADS)

Nikolić, Vlastimir; Petković, Dalibor; Lazov, Lyubomir; Milovančević, Miloš

2016-07-01

Water-jet assisted underwater laser cutting has shown some advantages as it produces much less turbulence, gas bubble and aerosols, resulting in a more gentle process. However, this process has relatively low efficiency due to different losses in water. It is important to determine which parameters are the most important for the process. In this investigation was analyzed the water-jet assisted underwater laser cutting parameters forecasting based on the different parameters. The method of ANFIS (adaptive neuro fuzzy inference system) was applied to the data in order to select the most influential factors for water-jet assisted underwater laser cutting parameters forecasting. Three inputs are considered: laser power, cutting speed and water-jet speed. The ANFIS process for variable selection was also implemented in order to detect the predominant factors affecting the forecasting of the water-jet assisted underwater laser cutting parameters. According to the results the combination of laser power cutting speed forms the most influential combination foe the prediction of water-jet assisted underwater laser cutting parameters. The best prediction was observed for the bottom kerf-width (R2 = 0.9653). The worst prediction was observed for dross area per unit length (R2 = 0.6804). According to the results, a greater improvement in estimation accuracy can be achieved by removing the unnecessary parameter.

Aquatic gilled mushrooms: Psathyrella fruiting in the Rogue River in southern Oregon.

PubMed

Frank, Jonathan L; Coffan, Robert A; Southworth, Darlene

2010-01-01

A species of Psathyrella (Basidiomycota) with true gills has been observed fruiting underwater in the clear, cold, flowing waters of the upper Rogue River in Oregon. Fruiting bodies develop and mature in the main channel, where they are constantly submerged, and were observed fruiting over 11 wk. These mushrooms develop underwater, not on wood recently washed into the river. Substrates include water-logged wood, gravel and the silty riverbed. DNA sequences of the ITS region and a portion of the ribosomal large subunit gene place this fungus in Psathyrella sensu stricto near P. atomata, P. fontinalis and P. superiorensis. Morphological characters distinguish the underwater mushroom from previously described species. Fruiting bodies have long fibrillose stipes with small diameter caps. Immature stages have a thin veil that is soon lost. Gills lack reddish edges. Cystidia are ventricose with subacute apices. Spores were observed as wedge-shape rafts released into gas pockets below the caps. Underwater gills and ballistospores indicate a recent adaptation to the stream environment. This particular river habitat combines the characteristics of spring-fed flows and cold, aerated water with woody debris in shallow depths on a fine volcanic substrate. Based on molecular and morphological evidence we conclude that the underwater mushrooms are a new species, Psathyrella aquatica. This report adds to the biodiversity of stream fungi that degrade woody substrates. The underwater environment is a new habitat for gilled mushrooms.

Archaeology Hijacked: Addressing the Historical Misappropriations of Maritime and Underwater Archaeology

NASA Astrophysics Data System (ADS)

Gately, Iain; Benjamin, Jonathan

2017-09-01

As a discipline that has grown up in the eyes of the camera, maritime and underwater archaeology has struggled historically to distinguish itself from early misrepresentations of it as adventure-seeking, treasure hunting and underwater salvage as popularized in the 1950s and 1960s. Though many professional archaeologists have successfully moved forward from this history through broader theoretical engagement and the development of the discipline within anthropology, public perception of archaeology under water has not advanced in stride. Central to this issue is the portrayal of underwater archaeology within popular culture and the representational structures from the 1950s and 1960s persistently used to introduce the profession to the public, through the consumption of popular books and especially television. This article explores representations of maritime and underwater archaeology to examine how the discipline has been consumed by the public, both methodologically and theoretically, through media. In order to interrogate this, we first examine maritime and underwater archaeology as a combined sub-discipline of archaeology and consider how it has been defined historically and in contemporary professional practice. Finally, we consider how practitioners can take a proactive approach to portray their work and convey archaeological media to the public. In this respect, we aim to advance the theoretical discussion in a way so as to reduce further cases whereby archaeology is accidentally misappropriated or deliberately hijacked.

Specialization for underwater hearing by the tympanic middle ear of the turtle, Trachemys scripta elegans

PubMed Central

Christensen-Dalsgaard, Jakob; Brandt, Christian; Willis, Katie L.; Christensen, Christian Bech; Ketten, Darlene; Edds-Walton, Peggy; Fay, Richard R.; Madsen, Peter T.; Carr, Catherine E.

2012-01-01

Turtles, like other amphibious animals, face a trade-off between terrestrial and aquatic hearing. We used laser vibrometry and auditory brainstem responses to measure their sensitivity to vibration stimuli and to airborne versus underwater sound. Turtles are most sensitive to sound underwater, and their sensitivity depends on the large middle ear, which has a compliant tympanic disc attached to the columella. Behind the disc, the middle ear is a large air-filled cavity with a volume of approximately 0.5 ml and a resonance frequency of approximately 500 Hz underwater. Laser vibrometry measurements underwater showed peak vibrations at 500–600 Hz with a maximum of 300 µm s−1 Pa−1, approximately 100 times more than the surrounding water. In air, the auditory brainstem response audiogram showed a best sensitivity to sound of 300–500 Hz. Audiograms before and after removing the skin covering reveal that the cartilaginous tympanic disc shows unchanged sensitivity, indicating that the tympanic disc, and not the overlying skin, is the key sound receiver. If air and water thresholds are compared in terms of sound intensity, thresholds in water are approximately 20–30 dB lower than in air. Therefore, this tympanic ear is specialized for underwater hearing, most probably because sound-induced pulsations of the air in the middle ear cavity drive the tympanic disc. PMID:22438494

Specialization for underwater hearing by the tympanic middle ear of the turtle, Trachemys scripta elegans.

PubMed

Christensen-Dalsgaard, Jakob; Brandt, Christian; Willis, Katie L; Christensen, Christian Bech; Ketten, Darlene; Edds-Walton, Peggy; Fay, Richard R; Madsen, Peter T; Carr, Catherine E

2012-07-22

Turtles, like other amphibious animals, face a trade-off between terrestrial and aquatic hearing. We used laser vibrometry and auditory brainstem responses to measure their sensitivity to vibration stimuli and to airborne versus underwater sound. Turtles are most sensitive to sound underwater, and their sensitivity depends on the large middle ear, which has a compliant tympanic disc attached to the columella. Behind the disc, the middle ear is a large air-filled cavity with a volume of approximately 0.5 ml and a resonance frequency of approximately 500 Hz underwater. Laser vibrometry measurements underwater showed peak vibrations at 500-600 Hz with a maximum of 300 µm s(-1) Pa(-1), approximately 100 times more than the surrounding water. In air, the auditory brainstem response audiogram showed a best sensitivity to sound of 300-500 Hz. Audiograms before and after removing the skin covering reveal that the cartilaginous tympanic disc shows unchanged sensitivity, indicating that the tympanic disc, and not the overlying skin, is the key sound receiver. If air and water thresholds are compared in terms of sound intensity, thresholds in water are approximately 20-30 dB lower than in air. Therefore, this tympanic ear is specialized for underwater hearing, most probably because sound-induced pulsations of the air in the middle ear cavity drive the tympanic disc.

Experimental investigation of efficient locomotion of underwater snake robots for lateral undulation and eel-like motion patterns.

PubMed

Kelasidi, Eleni; Liljebäck, Pål; Pettersen, Kristin Y; Gravdahl, Jan T

2015-01-01

Underwater snake robots offer many interesting capabilities for underwater operations. The long and slender structure of such robots provide superior capabilities for access through narrow openings and within confined areas. This is interesting for inspection and monitoring operations, for instance within the subsea oil and gas industry and within marine archeology. In addition, underwater snake robots can provide both inspection and intervention capabilities and are thus interesting candidates for the next generation inspection and intervention AUVs. Furthermore, bioinspired locomotion through oscillatory gaits, like lateral undulation and eel-like motion, is interesting from an energy efficiency point of view. Increasing the motion efficiency in terms of the achieved forward speed by improving the method of propulsion is a key issue for underwater robots. Moreover, energy efficiency is one of the main challenges for long-term autonomy of these systems. In this study, we will consider both these two aspects of efficiency. This paper considers the energy efficiency of swimming snake robots by presenting and experimentally investigating fundamental properties of the velocity and the power consumption of an underwater snake robot for both lateral undulation and eel-like motion patterns. In particular, we investigate the relationship between the parameters of the gait patterns, the forward velocity and the energy consumption for different motion patterns. The simulation and experimental results are seen to support the theoretical findings.

Visual accommodation and active pursuit of prey underwater in a plunge-diving bird: the Australasian gannet

PubMed Central

Machovsky-Capuska, Gabriel E.; Howland, Howard C.; Raubenheimer, David; Vaughn-Hirshorn, Robin; Würsig, Bernd; Hauber, Mark E.; Katzir, Gadi

2012-01-01

Australasian gannets (Morus serrator), like many other seabird species, locate pelagic prey from the air and perform rapid plunge dives for their capture. Prey are captured underwater either in the momentum (M) phase of the dive while descending through the water column, or the wing flapping (WF) phase while moving, using the wings for propulsion. Detection of prey from the air is clearly visually guided, but it remains unknown whether plunge diving birds also use vision in the underwater phase of the dive. Here we address the question of whether gannets are capable of visually accommodating in the transition from aerial to aquatic vision, and analyse underwater video footage for evidence that gannets use vision in the aquatic phases of hunting. Photokeratometry and infrared video photorefraction revealed that, immediately upon submergence of the head, gannet eyes accommodate and overcome the loss of greater than 45 D (dioptres) of corneal refractive power which occurs in the transition between air and water. Analyses of underwater video showed the highest prey capture rates during WF phase when gannets actively pursue individual fish, a behaviour that very likely involves visual guidance, following the transition after the plunge dive's M phase. This is to our knowledge the first demonstration of the capacity for visual accommodation underwater in a plunge diving bird while capturing submerged prey detected from the air. PMID:22874749

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

Physical gills prevent drowning of many wetland insects, spiders and plants.

PubMed

Pedersen, Ole; Colmer, Timothy D

2012-03-01

Insects, spiders and plants risk drowning in their wetland habitats. The slow diffusion of O(2) can cause asphyxiation when underwater, as O(2) supply cannot meet respiratory demands. Some animals and plants have found a common solution to the major challenge: how to breathe underwater with respiratory systems evolved for use in air? Hydrophobic surfaces on their bodies possess gas films that act as a 'physical gill' to collect O(2) when underwater and thus sustain respiration. In aquatic insects, this feature/process has been termed 'plastron respiration'. Here, we demonstrate the similarities in function between underwater respiration of insect (Aphelocheirus aestivalis) plastrons and gas films on leaves of wetland plants (Phalaris arundinacea) and also show the importance of these physical gills by the resulting changes upon their removal. The gas films provide an enlarged gas-water interface to enhance O(2) uptake underwater that is above that if only spiracles (insects) or stomata (plants) provided the gas-phase contact with the water. Body-surface gas films contribute to the survival of many insects, spiders and plants in aquatic and flood-prone environments.

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.

Natural and bio-inspired underwater adhesives: Current progress and new perspectives

NASA Astrophysics Data System (ADS)

Cui, Mengkui; Ren, Susu; Wei, Shicao; Sun, Chengjun; Zhong, Chao

2017-11-01

Many marine organisms harness diverse protein molecules as underwater adhesives to achieve strong and robust interfacial adhesion under dynamic and turbulent environments. Natural underwater adhesion phenomena thus provide inspiration for engineering adhesive materials that can perform in water or high-moisture settings for biomedical and industrial applications. Here we review examples of biological adhesives to show the molecular features of natural adhesives and discuss how such knowledge serves as a heuristic guideline for the rational design of biologically inspired underwater adhesives. In view of future bio-inspired research, we propose several potential opportunities, either in improving upon current L-3, 4-dihydroxyphenylalanine-based and coacervates-enabled adhesives with new features or engineering conceptually new types of adhesives that recapitulate important characteristics of biological adhesives. We underline the importance of viewing natural adhesives as dynamic materials, which owe their outstanding performance to the cellular coordination of protein expression, delivery, deposition, assembly, and curing of corresponding components with spatiotemporal control. We envision that the emerging synthetic biology techniques will provide great opportunities for advancing both fundamental and application aspects of underwater adhesives.

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.

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.

Strong underwater adhesives made by self-assembling multi-protein nanofibres.

PubMed

Zhong, Chao; Gurry, Thomas; Cheng, Allen A; Downey, Jordan; Deng, Zhengtao; Stultz, Collin M; Lu, Timothy K

2014-10-01

Many natural underwater adhesives harness hierarchically assembled amyloid nanostructures to achieve strong and robust interfacial adhesion under dynamic and turbulent environments. Despite recent advances, our understanding of the molecular design, self-assembly and structure-function relationships of these natural amyloid fibres remains limited. Thus, designing biomimetic amyloid-based adhesives remains challenging. Here, we report strong and multi-functional underwater adhesives obtained from fusing mussel foot proteins (Mfps) of Mytilus galloprovincialis with CsgA proteins, the major subunit of Escherichia coli amyloid curli fibres. These hybrid molecular materials hierarchically self-assemble into higher-order structures, in which, according to molecular dynamics simulations, disordered adhesive Mfp domains are exposed on the exterior of amyloid cores formed by CsgA. Our fibres have an underwater adhesion energy approaching 20.9 mJ m(-2), which is 1.5 times greater than the maximum of bio-inspired and bio-derived protein-based underwater adhesives reported thus far. Moreover, they outperform Mfps or curli fibres taken on their own and exhibit better tolerance to auto-oxidation than Mfps at pH ≥ 7.0.

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

DOA Estimation for Underwater Wideband Weak Targets Based on Coherent Signal Subspace and Compressed Sensing.

PubMed

Li, Jun; Lin, Qiu-Hua; Kang, Chun-Yu; Wang, Kai; Yang, Xiu-Ting

2018-03-18

Direction of arrival (DOA) estimation is the basis for underwater target localization and tracking using towed line array sonar devices. A method of DOA estimation for underwater wideband weak targets based on coherent signal subspace (CSS) processing and compressed sensing (CS) theory is proposed. Under the CSS processing framework, wideband frequency focusing is accompanied by a two-sided correlation transformation, allowing the DOA of underwater wideband targets to be estimated based on the spatial sparsity of the targets and the compressed sensing reconstruction algorithm. Through analysis and processing of simulation data and marine trial data, it is shown that this method can accomplish the DOA estimation of underwater wideband weak targets. Results also show that this method can considerably improve the spatial spectrum of weak target signals, enhancing the ability to detect them. It can solve the problems of low directional resolution and unreliable weak-target detection in traditional beamforming technology. Compared with the conventional minimum variance distortionless response beamformers (MVDR), this method has many advantages, such as higher directional resolution, wider detection range, fewer required snapshots and more accurate detection for weak targets.

Underwater image mosaicking and visual odometry

NASA Astrophysics Data System (ADS)

Sadjadi, Firooz; Tangirala, Sekhar; Sorber, Scott

2017-05-01

This paper summarizes the results of studies in underwater odometery using a video camera for estimating the velocity of an unmanned underwater vehicle (UUV). Underwater vehicles are usually equipped with sonar and Inertial Measurement Unit (IMU) - an integrated sensor package that combines multiple accelerometers and gyros to produce a three dimensional measurement of both specific force and angular rate with respect to an inertial reference frame for navigation. In this study, we investigate the use of odometry information obtainable from a video camera mounted on a UUV to extract vehicle velocity relative to the ocean floor. A key challenge with this process is the seemingly bland (i.e. featureless) nature of video data obtained underwater which could make conventional approaches to image-based motion estimation difficult. To address this problem, we perform image enhancement, followed by frame to frame image transformation, registration and mosaicking/stitching. With this approach the velocity components associated with the moving sensor (vehicle) are readily obtained from (i) the components of the transform matrix at each frame; (ii) information about the height of the vehicle above the seabed; and (iii) the sensor resolution. Preliminary results are presented.

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.

A universal glue: underwater adhesion of the secretion of the carnivorous flypaper plant Roridula gorgonias

PubMed Central

Voigt, Dagmar; Konrad, Wilfried; Gorb, Stanislav

2015-01-01

Glandular trichomes of the carnivorous plant Roridula gorgonias release a viscous resinous secretion. Its adhesion to hydrophilic and hydrophobic glass surfaces was measured in air and underwater. The underwater adhesion reached up to 91% (on hydrophilic glass) and 28% (on hydrophobic glass) of that measured in the air. After being submersed for 24 h in water, trichomes did not lose their ability to adhere to both types of glass surfaces underwater. We assume that acylglycerides and triterpenoids, which have been demonstrated previously to be main compounds of the secretion, cause the predominantly non-polar character and the insolubility in water. The robustness of the secretion to a wet environment presumably enables the plant to maintain its trapping function also under humid conditions and during rainy weather. PMID:25657836

Enhancing the Reliability of Head Nodes in Underwater Sensor Networks

PubMed Central

Min, Hong; Cho, Yookun; Heo, Junyoung

2012-01-01

Underwater environments are quite different from terrestrial environments in terms of the communication media and operating conditions associated with those environments. In underwater sensor networks, the probability of node failure is high because sensor nodes are deployed in harsher environments than ground-based networks. The sensor nodes are surrounded by salt water and moved around by waves and currents. Many studies have focused on underwater communication environments in an effort to improve the data transmission throughput. In this paper, we present a checkpointing scheme for the head nodes to quickly recover from a head node failure. Experimental results show that the proposed scheme enhances the reliability of the networks and makes them more efficient in terms of energy consumption and the recovery latency compared to the previous scheme without checkpointing. PMID:22438707

Design of Omni Directional Remotely Operated Vehicle (ROV)

NASA Astrophysics Data System (ADS)

Rahimuddin; Hasan, Hasnawiya; Rivai, Haryanti A.; Iskandar, Yanu; Claudio, P.

2018-02-01

Nowadays, underwater activities are increased with the increase of oil resources finding. The gap between demand and supply of oil and gas cause engineers to find oil and gas resources in deep water. In other side, high risk of working in deep underwater environment can cause a dangerous situation for human. Therefore, many research activities are developing an underwater vehicle to replace the human’s work such as ROV or Remotely Operated Vehicles. The vehicle operated using tether to transport the signals and electric power from the surface vehicle. Arrangements of weight, buoyancy, and the propeller placements are significant aspect in designing the vehicle’s performance. This paper presents design concept of ROV for survey and observation the underwater objects with interaction vectored propellers used for vehicle’s motions.

A Cost Effective Block Framing Scheme for Underwater Communication

PubMed Central

Shin, Soo-Young; Park, Soo-Hyun

2011-01-01

In this paper, the Selective Multiple Acknowledgement (SMA) method, based on Multiple Acknowledgement (MA), is proposed to efficiently reduce the amount of data transmission by redesigning the transmission frame structure and taking into consideration underwater transmission characteristics. The method is suited to integrated underwater system models, as the proposed method can handle the same amount of data in a much more compact frame structure without any appreciable loss of reliability. Herein, the performance of the proposed SMA method was analyzed and compared to those of the conventional Automatic Repeat-reQuest (ARQ), Block Acknowledgement (BA), block response, and MA methods. The efficiency of the underwater sensor network, which forms a large cluster and mostly contains uplink data, is expected to be improved by the proposed method. PMID:22247689

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.

Remotely operated submersible underwater suction apparatus

DOEpatents

Kristan, Louis L.

1990-01-01

A completely submersible, remotely operated underwater suction device for collection of irradiated materials in a nuclear pool is disclosed. The device includes a pump means for pumping water through the device, a filter means for capturing irradiated debris, remotely operated releasable connector means, a collection means and a means for remotely maneuvering the collection means. The components of the suction device may be changed and replaced underwater to take advantage of the excellent radiation shielding ability of water to thereby minimize exposure of personnel to radiation.

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

Phononic glass: a robust acoustic-absorption material.

PubMed

Jiang, Heng; Wang, Yuren

2012-08-01

In order to achieve strong wide band acoustic absorption under high hydrostatic pressure, an interpenetrating network structure is introduced into the locally resonant phononic crystal to fabricate a type of phononic composite material called "phononic glass." Underwater acoustic absorption coefficient measurements show that the material owns high underwater sound absorption coefficients over 0.9 in 12-30 kHz. Moreover, the quasi-static compressive behavior shows that the phononic glass has a compressive strength over 5 MPa which is crucial for underwater applications.

Robust analysis of an underwater navigational strategy in electrically heterogeneous corridors.

PubMed

Dimble, Kedar D; Ranganathan, Badri N; Keshavan, Jishnu; Humbert, J Sean

2016-08-01

Obstacles and other global stimuli provide relevant navigational cues to a weakly electric fish. In this work, robust analysis of a control strategy based on electrolocation for performing obstacle avoidance in electrically heterogeneous corridors is presented and validated. Static output feedback control is shown to achieve the desired goal of reflexive obstacle avoidance in such environments in simulation and experimentation. The proposed approach is computationally inexpensive and readily implementable on a small scale underwater vehicle, making underwater autonomous navigation feasible in real-time.

Underwater photography for bridge inspections.

DOT National Transportation Integrated Search

1983-01-01

A photographic technique was developed that enables divers in the Department to obtain clear photographs under typical conditions encountered in inspecting bridge components underwater. The equipment selected for the technique is inexpensive, readily...

Underwater inverse LIBS (iLIBS) for marine archaeology

NASA Astrophysics Data System (ADS)

Asmus, J.; Magde, M.; Elford, J.; Magde, D.; Parfenov, V.

2013-05-01

In recent years there have been enormous advances in nautical archaeology through developments in SONAR technologies as well as in manned and robotic submersible vehicles. The number of sunken vessel discoveries has escalated in many of the seas of the world in response to the widespread application of these and other new tools. Customarily, surviving artifacts within the debris field of a wreck are collected and then moved to laboratories, centers, or institutions for analyses and possible conservation. Frequently, the conservation phase involves chemical treatments to stabilize an artefact to standard temperature, pressure, and humidity instead of an undersea environment. Many of the artefacts encountered at an underwater site are now characterized and restored in-situ in accordance with modern trends in art conservation. Two examples of this trend are exemplified by the resting place of the wreck of the Titanic in the Atlantic and the Cancun Underwater Park in the Caribbean Sea. These two debris fields have been turned into museums for diving visitors. Several research groups have investigated the possibility of adapting the well-established analytical tool Laser Induced Breakdown Spectroscopy (LIBS) to in-situ elemental analyses of underwater cultural, historic, and archaeological artefacts where discovered, rather than as a phase of a salvage operation. As the underwater laser ablation associated with LIBS generates a "snowplough" shockwave within the aqueous matrix, the atomic emission spectrum is usually severely attenuated in escaping from the target. Consequently, probative experiments to date generally invoke a submerged air chamber or air jet to isolate water from the interaction zone as well as employ more complex double-pulse lasers. These measures impose severe logistical constraints on the examination of widely dispersed underwater artefacts. In order to overcome this constraint we report on water-immersion LIBS experiments performed with oblique laser irradiation and spectral detection at the complementary angle so as to view emission from behind the shockwave. Targets of silver, gold, and copper have been studied. It is found that this approach enables LIBS detection in water both in emission and in absorption. It appears that underwater inverse LIBS may be especially useful in underwater archaeology.

46 CFR 115.635 - Preliminary examination requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) If you exclusively use divers to examine the underwater hull plating, you must arrange to have a... underwater ROV as the predominate means to examine your vessel's hull plating, a preliminary examination and...

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...

Deformable Self-Propelled Micro-Object Comprising Underwater Oil Droplets

NASA Astrophysics Data System (ADS)

Banno, Taisuke; Asami, Arisa; Ueno, Naoko; Kitahata, Hiroyuki; Koyano, Yuki; Asakura, Kouichi; Toyota, Taro

2016-08-01

The self-propelled motion with deformation of micrometer-sized soft matter in water has potential application not only for underwater carriers or probes in very narrow spaces but also for understanding cell locomotion in terms of non-equilibrium physics. As far as we know, there have been no reports about micrometer-sized self-propelled soft matter mimicking amoeboid motion underwater. Here, we report an artificial molecular system of underwater oil droplets exhibiting self-propelled motion with deformation as an initial experimental model. We describe the heterogeneity in a deformable self-propelled oil droplet system in aqueous and oil phases and at their interface based on the behavior and interaction of surfactant and oil molecules. The current results have great importance for scientific frontiers such as developing deformable micro-swimmers and exploring the emergence of self-locomotion of oil droplet-type protocells.

Research on key technology of prognostic and health management for autonomous underwater vehicle

NASA Astrophysics Data System (ADS)

Zhou, Zhi

2017-12-01

Autonomous Underwater Vehicles (AUVs) are non-cable and autonomous motional underwater robotics. With a wide range of activities, it can reach thousands of kilometers. Because it has the advantages of wide range, good maneuverability, safety and intellectualization, it becomes an important tool for various underwater tasks. How to improve diagnosis accuracy of the AUVs electrical system faults, and how to repair AUVs by the information are the focus of navy in the world. In turn, ensuring safe and reliable operation of the system has very important significance to improve AUVs sailing performance. To solve these problems, in the paper the prognostic and health management(PHM) technology is researched and used to AUV, and the overall framework and key technology are proposed, such as data acquisition, feature extraction, fault diagnosis, failure prediction and so on.

Underwater explosive compaction-sintering of tungsten-copper coating on a copper surface

NASA Astrophysics Data System (ADS)

Chen, Xiang; Li, Xiaojie; Yan, Honghao; Wang, Xiaohong; Chen, Saiwei

2018-01-01

This study investigated underwater explosive compaction-sintering for coating a high-density tungsten-copper composite on a copper surface. First, 50% W-50% Cu tungsten-copper composite powder was prepared by mechanical alloying. The composite powder was pre-compacted and sintered by hydrogen. Underwater explosive compaction was carried out. Finally, a high-density tungsten-copper coating was obtained by diffusion sintering of the specimen after explosive compaction. A simulation of the underwater explosive compaction process showed that the peak value of the pressure in the coating was between 3.0 and 4.8 GPa. The hardness values of the tungsten-copper layer and the copper substrate were in the range of 87-133 and 49 HV, respectively. The bonding strength between the coating and the substrate was approximately 100-105 MPa.

20-meter underwater wireless optical communication link with 1.5 Gbps data rate.

PubMed

Shen, Chao; Guo, Yujian; Oubei, Hassan M; Ng, Tien Khee; Liu, Guangyu; Park, Ki-Hong; Ho, Kang-Ting; Alouini, Mohamed-Slim; Ooi, Boon S

2016-10-31

The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (~10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10^-5, and 3.0 × 10^-3, respectively, which pass well the forward error correction (FEC) criterion.

Utilization of volume correlation filters for underwater mine identification in LIDAR imagery

NASA Astrophysics Data System (ADS)

Walls, Bradley

2008-04-01

Underwater mine identification persists as a critical technology pursued aggressively by the Navy for fleet protection. As such, new and improved techniques must continue to be developed in order to provide measurable increases in mine identification performance and noticeable reductions in false alarm rates. In this paper we show how recent advances in the Volume Correlation Filter (VCF) developed for ground based LIDAR systems can be adapted to identify targets in underwater LIDAR imagery. Current automated target recognition (ATR) algorithms for underwater mine identification employ spatial based three-dimensional (3D) shape fitting of models to LIDAR data to identify common mine shapes consisting of the box, cylinder, hemisphere, truncated cone, wedge, and annulus. VCFs provide a promising alternative to these spatial techniques by correlating 3D models against the 3D rendered LIDAR data.

Action-specific effects underwater.

PubMed

Witt, Jessica K; Schuck, Donald M; Taylor, J Eric T

2011-01-01

Action-specific effects on perception are apparent in terrestrial environments. For example, targets that require more effort to walk, jump, or throw to look farther away than when the targets require less effort. Here, we examined whether action-specific effects would generalize to an underwater environment. Instead, perception might be geometrically precise, rather than action-specific, in an environment that is novel from an evolutionary perspective. We manipulated ease to swim by giving participants swimming flippers or taking them away. Those who estimated distance while wearing the flippers judged underwater targets to be closer than did participants who had taken them off. In addition, participants with better swimming ability judged the targets to be closer than did those with worse swimming ability. These results suggest perceived distance underwater is a function of the perceiver's ability to swim to the targets.

Underwater sound of rigid-hulled inflatable boats.

PubMed

Erbe, Christine; Liong, Syafrin; Koessler, Matthew Walter; Duncan, Alec J; Gourlay, Tim

2016-06-01

Underwater sound of rigid-hulled inflatable boats was recorded 142 times in total, over 3 sites: 2 in southern British Columbia, Canada, and 1 off Western Australia. Underwater sound peaked between 70 and 400 Hz, exhibiting strong tones in this frequency range related to engine and propeller rotation. Sound propagation models were applied to compute monopole source levels, with the source assumed 1 m below the sea surface. Broadband source levels (10-48 000 Hz) increased from 134 to 171 dB re 1 μPa @ 1 m with speed from 3 to 16 m/s (10-56 km/h). Source power spectral density percentile levels and 1/3 octave band levels are given for use in predictive modeling of underwater sound of these boats as part of environmental impact assessments.

A study on practical use of underwater abrasive water jet cutting

NASA Astrophysics Data System (ADS)

Yamaguchi, Hitoshi; Demura, Kenji

1993-09-01

The practicality of underwater abrasive water jet cutting technology was studied in experiments. A study of abrasives in slurried form showed that optimum polymer concentration can be selected to suit underwater conditions. For the long-distance transport of slurry from the ocean surface to the ocean floor, a direct supply system by hose proved to be practical. This system takes advantage of the insolubility of the slurry in water due to a difference in specific gravity. For cutting thick steel plate at great ocean depths, a simulation with a pressurized container revealed the requirements for actual cutting. Confirmation of remote cutting operations will become the most important technology in field applications. Underwater sound vibration characteristics were found to change significantly in direct response to modifications in cutting conditions. This will be important basic data to develop an effective sensoring method.

Deformable Self-Propelled Micro-Object Comprising Underwater Oil Droplets.

PubMed

Banno, Taisuke; Asami, Arisa; Ueno, Naoko; Kitahata, Hiroyuki; Koyano, Yuki; Asakura, Kouichi; Toyota, Taro

2016-08-09

The self-propelled motion with deformation of micrometer-sized soft matter in water has potential application not only for underwater carriers or probes in very narrow spaces but also for understanding cell locomotion in terms of non-equilibrium physics. As far as we know, there have been no reports about micrometer-sized self-propelled soft matter mimicking amoeboid motion underwater. Here, we report an artificial molecular system of underwater oil droplets exhibiting self-propelled motion with deformation as an initial experimental model. We describe the heterogeneity in a deformable self-propelled oil droplet system in aqueous and oil phases and at their interface based on the behavior and interaction of surfactant and oil molecules. The current results have great importance for scientific frontiers such as developing deformable micro-swimmers and exploring the emergence of self-locomotion of oil droplet-type protocells.

Survivability design for a hybrid underwater vehicle

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

Wang, Biao; Wu, Chao; Li, Xiang

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

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.

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.

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

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.

Imaging fall Chinook salmon redds in the Columbia River with a dual-frequency identification sonar

USGS Publications Warehouse

Tiffan, K.F.; Rondorf, D.W.; Skalicky, J.J.

2004-01-01

We tested the efficacy of a dual-frequency identification sonar (DIDSON) for imaging and enumeration of fall Chinook salmon Oncorhynchus tshawytscha redds in a spawning area below Bonneville Dam on the Columbia River. The DIDSON uses sound to form near-video-quality images and has the advantages of imaging in zero-visibility water and possessing a greater detection range and field of view than underwater video cameras. We suspected that the large size and distinct morphology of a fall Chinook salmon redd would facilitate acoustic imaging if the DIDSON was towed near the river bottom so as to cast an acoustic shadow from the tailspill over the redd pocket. We tested this idea by observing 22 different redds with an underwater video camera, spatially referencing their locations, and then navigating to them while imaging them with the DIDSON. All 22 redds were successfully imaged with the DIDSON. We subsequently conducted redd searches along transects to compare the number of redds imaged by the DIDSON with the number observed using an underwater video camera. We counted 117 redds with the DIDSON and 81 redds with the underwater video camera. Only one of the redds observed with the underwater video camera was not also documented by the DIDSON. In spite of the DIDSON's high cost, it may serve as a useful tool for enumerating fall Chinook salmon redds in conditions that are not conducive to underwater videography.

Design and implementation of an omni-directional underwater acoustic micro-modem based on a low-power micro-controller unit.

PubMed

Won, Tae-Hee; Park, Sung-Joon

2012-01-01

For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication.

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.

Solving Wakulla Springs underwater mysteries. Using GPS to map Florida's underground caverns

USGS Publications Warehouse

Am, Ende B.

2002-01-01

Located in the Woodville Karst Plain stretching south from Tallahassee to the Gulf of Mexico, Florida's Wakulla Springs is one of the largest and deepest freshwater Springs in the world. It is also a gateway into one of the longest underwater cave system in the United States, a system that remained largely unexplored until recently. Soon, however, thanks to one of the world's most extreme scientific and exploration-related diving projects ever undertaken, visitors to Wakulla Springs State Park will be able to take a virtual tour through the Spring's huge underwater labyrinth. Using such cutting-edge technology as a 3D Digital Wall Mapper (DWM) and the Global Positioning System (GPS), the Wakulla 2 Expedition - with 151 volunteer cave divers, scientists and engineers from all over the world - created the world's first three-dimensional digital map of an underwater cave. Underwater caves are priceless treasures, helping supply fresh water to the region as well as acting as 'time capsules' to the past. Home to creatures found in few other places, areas such as Wakulla face threats of pollution and over-development. Wakulla 2 hopes their 3D interactive 'swim through' will help increase the understanding and preservation of these important areas.

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

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.

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.

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.

A network coding based routing protocol for underwater sensor networks.

PubMed

Wu, Huayang; Chen, Min; Guan, Xin

2012-01-01

Due to the particularities of the underwater environment, some negative factors will seriously interfere with data transmission rates, reliability of data communication, communication range, and network throughput and energy consumption of underwater sensor networks (UWSNs). Thus, full consideration of node energy savings, while maintaining a quick, correct and effective data transmission, extending the network life cycle are essential when routing protocols for underwater sensor networks are studied. In this paper, we have proposed a novel routing algorithm for UWSNs. To increase energy consumption efficiency and extend network lifetime, we propose a time-slot based routing algorithm (TSR).We designed a probability balanced mechanism and applied it to TSR. The theory of network coding is introduced to TSBR to meet the requirement of further reducing node energy consumption and extending network lifetime. Hence, time-slot based balanced network coding (TSBNC) comes into being. We evaluated the proposed time-slot based balancing routing algorithm and compared it with other classical underwater routing protocols. The simulation results show that the proposed protocol can reduce the probability of node conflicts, shorten the process of routing construction, balance energy consumption of each node and effectively prolong the network lifetime.

Auditory and behavioral responses of bottlenose dolphins (Tursiops truncatus) and a beluga whale (Delphinapterus leucas) to impulsive sounds resembling distant signatures of underwater explosions.

PubMed

Finneran, J J; Schlundt, C E; Carder, D A; Clark, J A; Young, J A; Gaspin, J B; Ridgway, S H

2000-07-01

A behavioral response paradigm was used to measure masked underwater hearing thresholds in two bottlenose dolphins and one beluga whale before and after exposure to impulsive underwater sounds with waveforms resembling distant signatures of underwater explosions. An array of piezoelectric transducers was used to generate impulsive sounds with waveforms approximating those predicted from 5 or 500 kg HBX-1 charges at ranges from 1.5 to 55.6 km. At the conclusion of the study, no temporary shifts in masked-hearing thresholds (MTTSs), defined as a 6-dB or larger increase in threshold over pre-exposure levels, had been observed at the highest impulse level generated (500 kg at 1.7 km, peak pressure 70 kPa); however, disruptions of the animals' trained behaviors began to occur at exposures corresponding to 5 kg at 9.3 km and 5 kg at 1.5 km for the dolphins and 500 kg at 1.9 km for the beluga whale. These data are the first direct information regarding the effects of distant underwater explosion signatures on the hearing abilities of odontocetes.

DOA Estimation for Underwater Wideband Weak Targets Based on Coherent Signal Subspace and Compressed Sensing

PubMed Central

2018-01-01

Direction of arrival (DOA) estimation is the basis for underwater target localization and tracking using towed line array sonar devices. A method of DOA estimation for underwater wideband weak targets based on coherent signal subspace (CSS) processing and compressed sensing (CS) theory is proposed. Under the CSS processing framework, wideband frequency focusing is accompanied by a two-sided correlation transformation, allowing the DOA of underwater wideband targets to be estimated based on the spatial sparsity of the targets and the compressed sensing reconstruction algorithm. Through analysis and processing of simulation data and marine trial data, it is shown that this method can accomplish the DOA estimation of underwater wideband weak targets. Results also show that this method can considerably improve the spatial spectrum of weak target signals, enhancing the ability to detect them. It can solve the problems of low directional resolution and unreliable weak-target detection in traditional beamforming technology. Compared with the conventional minimum variance distortionless response beamformers (MVDR), this method has many advantages, such as higher directional resolution, wider detection range, fewer required snapshots and more accurate detection for weak targets. PMID:29562642

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

Free-space and underwater GHz data transmission using AlGaInN laser diode technology

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.

2016-05-01

Laser diodes fabricated from the AlGaInN material system is an emerging technology for defence and security applications; in particular for free space laser communication. Conventional underwater communication is done acoustically with very slow data rates, short reach, and vulnurable for interception. AlGaInN blue-green laser diode technology allows the possibility of both airbourne links and underwater telecom that operate at very fast data rates (GHz), long reach (100's of metres underwater) and can also be quantum encrypted. The latest developments in AlGaInN laser diode technology are reviewed for defence and security applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of <100mW. Visible light communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Galliumnitride (GaN) blue laser diode is reported in free-space and underwater.

A Network Coding Based Routing Protocol for Underwater Sensor Networks

PubMed Central

Wu, Huayang; Chen, Min; Guan, Xin

2012-01-01

Due to the particularities of the underwater environment, some negative factors will seriously interfere with data transmission rates, reliability of data communication, communication range, and network throughput and energy consumption of underwater sensor networks (UWSNs). Thus, full consideration of node energy savings, while maintaining a quick, correct and effective data transmission, extending the network life cycle are essential when routing protocols for underwater sensor networks are studied. In this paper, we have proposed a novel routing algorithm for UWSNs. To increase energy consumption efficiency and extend network lifetime, we propose a time-slot based routing algorithm (TSR).We designed a probability balanced mechanism and applied it to TSR. The theory of network coding is introduced to TSBR to meet the requirement of further reducing node energy consumption and extending network lifetime. Hence, time-slot based balanced network coding (TSBNC) comes into being. We evaluated the proposed time-slot based balancing routing algorithm and compared it with other classical underwater routing protocols. The simulation results show that the proposed protocol can reduce the probability of node conflicts, shorten the process of routing construction, balance energy consumption of each node and effectively prolong the network lifetime. PMID:22666045

Self-Assembling Multi-Component Nanofibers for Strong Bioinspired Underwater Adhesives

PubMed Central

Zhong, Chao; Gurry, Thomas; Cheng, Allen A; Downey, Jordan; Deng, Zhengtao; Stultz, Collin M.; Lu, Timothy K

2014-01-01

Many natural underwater adhesives harness hierarchically assembled amyloid nanostructures to achieve strong and robust interfacial adhesion under dynamic and turbulent environments. Despite recent advances, our understanding of the molecular design, self-assembly, and structure-function relationship of those natural amyloid fibers remains limited. Thus, designing biomimetic amyloid-based adhesives remains challenging. Here, we report strong and multi-functional underwater adhesives obtained from fusing mussel foot proteins (Mfps) of Mytilus galloprovincialis with CsgA proteins, the major subunit of Escherichia coli amyloid curli fibers. These hybrid molecular materials hierarchically self-assemble into higher-order structures, in which, according to molecular dynamics simulations, disordered adhesive Mfp domains are exposed on the exterior of amyloid cores formed by CsgA. Our fibers have an underwater adhesion energy approaching 20.9 mJ/m2, which is 1.5 times greater than the maximum of bio-inspired and bio-derived protein-based underwater adhesives reported thus far. Moreover, they outperform Mfps or curli fibers taken on their own at all pHs and exhibit better tolerance to auto-oxidation than Mfps at pH ≥7.0. This work establishes a platform for engineering multi-component self-assembling materials inspired by nature. PMID:25240674

Underwater microwave ignition of hydrophobic thermite powder enabled by the bubble-marble effect

NASA Astrophysics Data System (ADS)

Meir, Yehuda; Jerby, Eli

2015-08-01

Highly energetic thermite reactions could be useful for a variety of combustion and material-processing applications, but their usability is yet limited by their hard ignition conditions. Furthermore, in virtue of their zero-oxygen balance, exothermic thermite reactions may also occur underwater. However, this feature is also hard to utilize because of the hydrophobic properties of the thermite powder, and its tendency to agglomerate on the water surface rather than to sink into the water. The recently discovered bubble-marble (BM) effect enables the insertion and confinement of a thermite-powder batch into water by a magnetic field. Here, we present a phenomenon of underwater ignition of a thermite-BM by localized microwaves. The thermite combustion underwater is observed in-situ, and its microwave absorption and optical spectral emission are detected. The vapour pressure generated by the thermite reaction is measured and compared to theory. The combustion products are examined ex-situ by X-ray photo-electron spectroscopy which verifies the thermite reaction. Potential applications of this underwater combustion effect are considered, e.g., for detonation, wet welding, thermal drilling, material processing, thrust generation, and composite-material production, also for other oxygen-free environments.

Underwater microwave ignition of hydrophobic thermite powder enabled by the bubble-marble effect

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

Meir, Yehuda; Jerby, Eli, E-mail: jerby@eng.tau.ac.il

Highly energetic thermite reactions could be useful for a variety of combustion and material-processing applications, but their usability is yet limited by their hard ignition conditions. Furthermore, in virtue of their zero-oxygen balance, exothermic thermite reactions may also occur underwater. However, this feature is also hard to utilize because of the hydrophobic properties of the thermite powder, and its tendency to agglomerate on the water surface rather than to sink into the water. The recently discovered bubble-marble (BM) effect enables the insertion and confinement of a thermite-powder batch into water by a magnetic field. Here, we present a phenomenon ofmore » underwater ignition of a thermite-BM by localized microwaves. The thermite combustion underwater is observed in-situ, and its microwave absorption and optical spectral emission are detected. The vapour pressure generated by the thermite reaction is measured and compared to theory. The combustion products are examined ex-situ by X-ray photo-electron spectroscopy which verifies the thermite reaction. Potential applications of this underwater combustion effect are considered, e.g., for detonation, wet welding, thermal drilling, material processing, thrust generation, and composite-material production, also for other oxygen-free environments.« less

Experimental demonstration of remote, passive acousto-optic sensing.

PubMed

Antonelli, Lynn; Blackmon, Fletcher

2004-12-01

Passively detecting underwater sound from the air can allow aircraft and surface vessels to monitor the underwater acoustic environment. Experimental research into an optical hydrophone is being conducted for remote, aerial detection of underwater sound. A laser beam is directed onto the water surface to measure the velocity of the vibrations occurring as the underwater acoustic signal reaches the water surface. The acoustically generated surface vibrations modulate the phase of the laser beam. Sound detection occurs when the laser is reflected back towards the sensor. Therefore, laser alignment on the specularly reflecting water surface is critical. As the water surface moves, the laser beam is reflected away from the photodetector and no signal is obtained. One option to mitigate this problem is to continually steer the laser onto a spot on the water surface that provides a direct back-reflection. Results are presented from a laboratory test that investigates the feasibility of the acousto-optic sensor detection on hydrostatic and hydrodynamic surfaces using a laser Doppler vibrometer in combination with a laser-based, surface normal glint tracker for remotely detecting underwater sound. This paper outlines the acousto-optic sensor and tracker concepts and presents experimental results comparing sensor operation under various sea surface conditions.

ULTRA: Underwater Localization for Transit and Reconnaissance Autonomy

NASA Technical Reports Server (NTRS)

Huntsberger, Terrance L.

2013-01-01

This software addresses the issue of underwater localization of unmanned vehicles and the inherent drift in their onboard sensors. The software gives a 2 to 3 factor of improvement over the state-of-the-art underwater localization algorithms. The software determines the localization (position, heading) of an AUV (autonomous underwater vehicle) in environments where there is no GPS signal. It accomplishes this using only the commanded position, onboard gyros/accelerometers, and the bathymetry of the bottom provided by an onboard sonar system. The software does not rely on an onboard bathymetry dataset, but instead incrementally determines the position of the AUV while mapping the bottom. In order to enable long-distance underwater navigation by AUVs, a localization method called ULTRA uses registration of the bathymetry data products produced by the onboard forward-looking sonar system for hazard avoidance during a transit to derive the motion and pose of the AUV in order to correct the DR (dead reckoning) estimates. The registration algorithm uses iterative point matching (IPM) combined with surface interpolation of the Iterative Closest Point (ICP) algorithm. This method was used previously at JPL for onboard unmanned ground vehicle localization, and has been optimized for efficient computational and memory use.

Underwater Grass Comeback Helps Chesapeake Bay

EPA Pesticide Factsheets

The fortified Susquehanna Flats, the largest bed of underwater grasses in the Chesapeake Bay, seems able to withstand a major weather punch. Its resilience is contributing to an overall increase in the Bay’s submerged aquatic vegetation.

An overview of underwater remotely manned Systems and sub-systems

NASA Technical Reports Server (NTRS)

Rechnitzer, A., B.

1975-01-01

A current overview of how the underwater facet of remotely manned systems has progressed since 1972 is presented. The current approaches being pursued and the success of American and foreign technology is assessed.

Preliminary calibration of the ACP safeguards neutron counter

NASA Astrophysics Data System (ADS)

Lee, T. H.; Kim, H. D.; Yoon, J. S.; Lee, S. Y.; Swinhoe, M.; Menlove, H. O.

2007-10-01

The Advanced Spent Fuel Conditioning Process (ACP), a kind of pyroprocess, has been developed at the Korea Atomic Energy Research Institute (KAERI). Since there is no IAEA safeguards criteria for this process, KAERI has developed a neutron coincidence counter to make it possible to perform a material control and accounting (MC&A) for its ACP materials for the purpose of a transparency in the peaceful uses of nuclear materials at KAERI. The test results of the ACP Safeguards Neutron Counter (ASNC) show a satisfactory performance for the Doubles count measurement with a low measurement error for its cylindrical sample cavity. The neutron detection efficiency is about 21% with an error of ±1.32% along the axial direction of the cavity. Using two 252Cf neutron sources, we obtained various parameters for the Singles and Doubles rates for the ASNC. The Singles, Doubles, and Triples rates for a 252Cf point source were obtained by using the MCNPX code and the results for the ft8 cap multiplicity tally option with the values of ɛ, fd, and ft measured with a strong source most closely match the measurement results to within a 1% error. A preliminary calibration curve for the ASNC was generated by using the point model equation relationship between 244Cm and 252Cf and the calibration coefficient for the non-multiplying sample is 2.78×10 5 (Doubles counts/s/g 244Cm). The preliminary calibration curves for the ACP samples were also obtained by using an MCNPX simulation. A neutron multiplication influence on an increase of the Doubles rate for a metal ingot and UO2 powder is clearly observed. These calibration curves will be modified and complemented, when hot calibration samples become available. To verify the validity of this calibration curve, a measurement of spent fuel standards for a known 244Cm mass will be performed in the near future.

Nemo:. a Project for a KM3 Underwater Detector for Astrophysical Neutrinos in the Mediterranean Sea

NASA Astrophysics Data System (ADS)

Amore, I.; Aiello, S.; Ambriola, M.; Ameli, F.; Anghinolfi, M.; Anzalone, A.; Barbarino, G.; Barbarito, E.; Battaglieri, M.; Bellotti, R.; Beverini, N.; Bonori, M.; Bouhadef, B.; Brescia, M.; Cacopardo, G.; Cafagna, F.; Capone, A.; Caponetto, L.; Castorina, E.; Ceres, A.; Chiarusi, T.; Circella, M.; Cocimano, R.; Coniglione, R.; Cordelli, M.; Costa, M.; Cuneo, S.; D'Amico, A.; de Bonis, G.; de Marzo, C.; de Rosa, G.; de Vita, R.; Distefano, C.; Falchini, E.; Fiorello, C.; Flaminio, V.; Fratini, K.; Gabrielli, A.; Galeotti, S.; Gandolfi, E.; Giacomelli, G.; Giorgi, F.; Grimaldi, A.; Habel, R.; Leonora, E.; Lonardo, A.; Longo, G.; Lo Presti, D.; Lucarelli, F.; Maccioni, E.; Margiotta, A.; Martini, A.; Masullo, R.; Megna, R.; Migneco, E.; Mongelli, M.; Montaruli, T.; Morganti, M.; Musumeci, M. S.; Nicolau, C. A.; Orlando, A.; Osipenko, M.; Osteria, G.; Papaleo, R.; Pappalardo, V.; Petta, C.; Piattelli, P.; Raia, G.; Randazzo, N.; Reito, S.; Ricco, G.; Riccobene, G.; Ripani, M.; Rovelli, A.; Ruppi, M.; Russo, G. V.; Russo, S.; Sapienza, P.; Sedita, M.; Shirokov, E.; Simeone, F.; Sipala, V.; Spurio, M.; Taiuti, M.; Terreni, G.; Trasatti, L.; Urso, S.; Valente, V.; Vicini, P.

The status of the project is described: the activity on long term characterization of water optical and oceanographic parameters at the Capo Passero site candidate for the Mediterranean km3 neutrino telescope; the feasibility study; the physics performances and underwater technology for the km3; the activity on NEMO Phase 1, a technological demonstrator that has been deployed at 2000 m depth 25 km offshore Catania; the realization of an underwater infrastructure at 3500 m depth at the candidate site (NEMO Phase 2).

Operational experience in underwater photogrammetry

NASA Astrophysics Data System (ADS)

Leatherdale, John D.; John Turner, D.

Underwater photogrammetry has become established as a cost-effective technique for inspection and maintenance of platforms and pipelines for the offshore oil industry. A commercial service based in Scotland operates in the North Sea, USA, Brazil, West Africa and Australia. 70 mm cameras and flash units are built for the purpose and analytical plotters and computer graphics systems are used for photogrammetric measurement and analysis of damage, corrosion, weld failures and redesign of underwater structures. Users are seeking simple, low-cost systems for photogrammetric analysis which their engineers can use themselves.

The application of dummy noise adaptive Kalman filter in underwater navigation

NASA Astrophysics Data System (ADS)

Li, Song; Zhang, Chun-Hua; Luan, Jingde

2011-10-01

The track of underwater target is easy to be affected by the various by the various factors, which will cause poor performance in Kalman filter with the error in the state and measure model. In order to solve the situation, a method is provided with dummy noise compensative technology. Dummy noise is added to state and measure model artificially, and then the question can be solved by the adaptive Kalman filter with unknown time-changed statistical character. The simulation result of underwater navigation proves the algorithm is effective.

Underwater acoustic wireless sensor networks: advances and future trends in physical, MAC and routing layers.

PubMed

Climent, Salvador; Sanchez, Antonio; Capella, Juan Vicente; Meratnia, Nirvana; Serrano, Juan Jose

2014-01-06

This survey aims to provide a comprehensive overview of the current research on underwater wireless sensor networks, focusing on the lower layers of the communication stack, and envisions future trends and challenges. It analyzes the current state-of-the-art on the physical, medium access control and routing layers. It summarizes their security threads and surveys the currently proposed studies. Current envisioned niches for further advances in underwater networks research range from efficient, low-power algorithms and modulations to intelligent, energy-aware routing and medium access control protocols.

Upgrade of ROV Super GNOME Pro for Underwater Monitoring in the Caspian Sea

NASA Astrophysics Data System (ADS)

Rozman, B. Ya.; Elkin, A. V.; Kaptsov, A. S.; Ermakov, I. D.; Ermakov, D. I.; Krasnov, V. G.; Kondrashov, L. S.

2018-01-01

A description and characteristics of the small-size remotely operated underwater vehicle Super GNOME pro are given. The main technical innovations and upgrades of the vehicle are considered along with the reasons and aims of these improvements. The innovations were evaluated during expedition work in northern Caspian Sea in 2016, which demonstrated good results. Further upgrades include installation of a sediment-penetrating thermometer for measuring the thermal background of benthonic soil and an underwater dosimeter/radiometer for assessing the radiation background of water areas.

Evaluation of Underwater Adhesives and Friction Coatings for In Situ Attachment of Fiber Optic Sensor System for Subsea Applications

NASA Technical Reports Server (NTRS)

Tang, Henry H.; Le, Suy Q.; Orndoff, Evelyne S.; Smith, Frederick D.; Tapia, Alma S.; Brower, David V.

2012-01-01

Integrity and performance monitoring of subsea pipelines and structures provides critical information for managing offshore oil and gas production operation and preventing environmentally damaging and costly catastrophic failure. Currently pipeline monitoring devices require ground assembly and installation prior to the underwater deployment of the pipeline. A monitoring device that could be installed in situ on the operating underwater structures could enhance the productivity and improve the safety of current offshore operation. Through a Space Act Agreement (SAA) between the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) and Astro Technology, Inc. (ATI), JSC provides technical expertise and testing facilities to support the development of fiber optic sensor technologies by ATI. This paper details the first collaboration effort between NASA JSC and ATI in evaluating underwater applicable adhesives and friction coatings for attaching fiber optic sensor system to subsea pipeline. A market survey was conducted to examine different commercial ]off ]the ]shelf (COTS) underwater adhesive systems and to select adhesive candidates for testing and evaluation. Four COTS epoxy based underwater adhesives were selected and evaluated. The adhesives were applied and cured in simulated seawater conditions and then evaluated for application characteristics and adhesive strength. The adhesive that demonstrated the best underwater application characteristics and highest adhesive strength were identified for further evaluation in developing an attachment system that could be deployed in the harsh subsea environment. Various friction coatings were also tested in this study to measure their shear strengths for a mechanical clamping design concept for attaching fiber optic sensor system. A COTS carbide alloy coating was found to increase the shear strength of metal to metal clamping interface by up to 46 percent. This study provides valuable data for assessing the feasibility of developing the next generation fiber optic senor system that could be retrofitted onto existing subsea pipeline structures.

A bioinspired elastin-based protein for a cytocompatible underwater adhesive.

PubMed

Brennan, M Jane; Kilbride, Bridget F; Wilker, Jonathan J; Liu, Julie C

2017-04-01

The development of adhesives that can be applied and create strong bonds underwater is a significant challenge for materials engineering. When the adhesive is intended for biomedical applications, further criteria, such as biocompatibility, must be met. Current biomedical adhesive technologies do not meet these needs. In response, we designed a bioinspired protein system that shows promise to achieve biocompatible underwater adhesion coupled with environmentally responsive behavior that is "smart" - that is, it can be tuned to suit a specific application. The material, ELY 16 , is constructed from an elastin-like polypeptide (ELP) that can be produced in high yields from Escherichia coli and can coacervate in response to environmental factors such as temperature, pH, and salinity. To confer wet adhesion, we utilized design principles from marine organisms such as mussels and sandcastle worms. When expressed, ELY 16 is rich in tyrosine. Upon modification with the tyrosinase enzyme to form mELY 16 , the tyrosine residues are converted to 3,4-dihydroxyphenylalanine (DOPA). Both ELY 16 and mELY 16 exhibit cytocompatibility and significant dry adhesion strength (>2 MPa). Modification with DOPA increases protein adsorption to glass and provides moderate adhesion strength (∼240 kPa) in a highly humid environment. Furthermore, this ELP exhibits a tunable phase transition behavior that can be formulated to coacervate in physiological conditions and provides a convenient mechanism for application underwater. Finally, mELY 16 possesses significantly higher adhesion strength in dry, humid, and underwater environments compared with a commercially available fibrin sealant. To our knowledge, mELY 16 provides the strongest bonds of any rationally designed protein when used completely underwater, and its high yields make it more viable for commercial application compared to natural adhesive proteins. In conclusion, this ELP shows great potential to be a new "smart" underwater adhesive. Copyright © 2017 Elsevier Ltd. All rights reserved.

Smelling and Tasting Underwater.

ERIC Educational Resources Information Center

Atema, Jelle

1980-01-01

Discusses differences between smell and taste, comparing these senses in organisms in aquatic and terrestrial environments. Describes the chemical environment underwater and in air, differences in chemoreceptors to receive stimuli, and the organs, brain, and behavior involved in chemoreception. (CS)

Parametric geometric model and hydrodynamic shape optimization of a flying-wing structure underwater glider

NASA Astrophysics Data System (ADS)

Wang, Zhen-yu; Yu, Jian-cheng; Zhang, Ai-qun; Wang, Ya-xing; Zhao, Wen-tao

2017-12-01

Combining high precision numerical analysis methods with optimization algorithms to make a systematic exploration of a design space has become an important topic in the modern design methods. During the design process of an underwater glider's flying-wing structure, a surrogate model is introduced to decrease the computation time for a high precision analysis. By these means, the contradiction between precision and efficiency is solved effectively. Based on the parametric geometry modeling, mesh generation and computational fluid dynamics analysis, a surrogate model is constructed by adopting the design of experiment (DOE) theory to solve the multi-objects design optimization problem of the underwater glider. The procedure of a surrogate model construction is presented, and the Gaussian kernel function is specifically discussed. The Particle Swarm Optimization (PSO) algorithm is applied to hydrodynamic design optimization. The hydrodynamic performance of the optimized flying-wing structure underwater glider increases by 9.1%.

Efficient Data Gathering in 3D Linear Underwater Wireless Sensor Networks Using Sink Mobility

PubMed Central

Akbar, Mariam; Javaid, Nadeem; Khan, Ayesha Hussain; Imran, Muhammad; Shoaib, Muhammad; Vasilakos, Athanasios

2016-01-01

Due to the unpleasant and unpredictable underwater environment, designing an energy-efficient routing protocol for underwater wireless sensor networks (UWSNs) demands more accuracy and extra computations. In the proposed scheme, we introduce a mobile sink (MS), i.e., an autonomous underwater vehicle (AUV), and also courier nodes (CNs), to minimize the energy consumption of nodes. MS and CNs stop at specific stops for data gathering; later on, CNs forward the received data to the MS for further transmission. By the mobility of CNs and MS, the overall energy consumption of nodes is minimized. We perform simulations to investigate the performance of the proposed scheme and compare it to preexisting techniques. Simulation results are compared in terms of network lifetime, throughput, path loss, transmission loss and packet drop ratio. The results show that the proposed technique performs better in terms of network lifetime, throughput, path loss and scalability. PMID:27007373

Risk Factors Detection for Strategic Importance Objectives in Littoral Areas

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

With the invention and development of underwater explosive devices the need to neutralize them has also appeared, both for enemy and for own devices once conflicts are finished. The fight against active underwater explosive devices is a very complicated action that requires a very careful approach. Also, in the current context, strategic importance objectives located in the littoral areas can also become targets for divers or fast boats (suicidal actions).The system for detection, localization, tracking and identification of risk factors for strategic importance objectives in littoral areas has as one of its components an AUV and a hydro-acoustic sub-system for determining the ‘fingerprints’ of potential targets. The overall system will provide support for main missions such as underwater environment surveillance (detection, monitoring) in harbor areas and around other coast objectives, ship anchorage areas, mandatory pass points and also provide warnings about the presence of underwater and surface dangers in the interest areas.

Impact of MAC Delay on AUV Localization: Underwater Localization Based on Hyperbolic Frequency Modulation Signal

PubMed Central

2018-01-01

Medium Access Control (MAC) delay which occurs between the anchor node’s transmissions is one of the error sources in underwater localization. In particular, in AUV localization, the MAC delay significantly degrades the ranging accuracy. The Cramer-Rao Low Bound (CRLB) definition theoretically proves that the MAC delay significantly degrades the localization performance. This paper proposes underwater localization combined with multiple access technology to decouple the localization performance from the MAC delay. Towards this goal, we adopt hyperbolic frequency modulation (HFM) signal that provides multiplexing based on its good property, high-temporal correlation. Owing to the multiplexing ability of the HFM signal, the anchor nodes can transmit packets without MAC delay, i.e., simultaneous transmission is possible. In addition, the simulation results show that the simultaneous transmission is not an optional communication scheme, but essential for the localization of mobile object in underwater. PMID:29373518

Efficient Data Gathering in 3D Linear Underwater Wireless Sensor Networks Using Sink Mobility.

PubMed

Akbar, Mariam; Javaid, Nadeem; Khan, Ayesha Hussain; Imran, Muhammad; Shoaib, Muhammad; Vasilakos, Athanasios

2016-03-19

Due to the unpleasant and unpredictable underwater environment, designing an energy-efficient routing protocol for underwater wireless sensor networks (UWSNs) demands more accuracy and extra computations. In the proposed scheme, we introduce a mobile sink (MS), i.e., an autonomous underwater vehicle (AUV), and also courier nodes (CNs), to minimize the energy consumption of nodes. MS and CNs stop at specific stops for data gathering; later on, CNs forward the received data to the MS for further transmission. By the mobility of CNs and MS, the overall energy consumption of nodes is minimized. We perform simulations to investigate the performance of the proposed scheme and compare it to preexisting techniques. Simulation results are compared in terms of network lifetime, throughput, path loss, transmission loss and packet drop ratio. The results show that the proposed technique performs better in terms of network lifetime, throughput, path loss and scalability.

Impact of MAC Delay on AUV Localization: Underwater Localization Based on Hyperbolic Frequency Modulation Signal.

PubMed

Kim, Sungryul; Yoo, Younghwan

2018-01-26

Medium Access Control (MAC) delay which occurs between the anchor node's transmissions is one of the error sources in underwater localization. In particular, in AUV localization, the MAC delay significantly degrades the ranging accuracy. The Cramer-Rao Low Bound (CRLB) definition theoretically proves that the MAC delay significantly degrades the localization performance. This paper proposes underwater localization combined with multiple access technology to decouple the localization performance from the MAC delay. Towards this goal, we adopt hyperbolic frequency modulation (HFM) signal that provides multiplexing based on its good property, high-temporal correlation. Owing to the multiplexing ability of the HFM signal, the anchor nodes can transmit packets without MAC delay, i.e., simultaneous transmission is possible. In addition, the simulation results show that the simultaneous transmission is not an optional communication scheme, but essential for the localization of mobile object in underwater.

Deformable Self-Propelled Micro-Object Comprising Underwater Oil Droplets

PubMed Central

Banno, Taisuke; Asami, Arisa; Ueno, Naoko; Kitahata, Hiroyuki; Koyano, Yuki; Asakura, Kouichi; Toyota, Taro

2016-01-01

The self-propelled motion with deformation of micrometer-sized soft matter in water has potential application not only for underwater carriers or probes in very narrow spaces but also for understanding cell locomotion in terms of non-equilibrium physics. As far as we know, there have been no reports about micrometer-sized self-propelled soft matter mimicking amoeboid motion underwater. Here, we report an artificial molecular system of underwater oil droplets exhibiting self-propelled motion with deformation as an initial experimental model. We describe the heterogeneity in a deformable self-propelled oil droplet system in aqueous and oil phases and at their interface based on the behavior and interaction of surfactant and oil molecules. The current results have great importance for scientific frontiers such as developing deformable micro-swimmers and exploring the emergence of self-locomotion of oil droplet-type protocells. PMID:27503336

Complex coacervates as a foundation for synthetic underwater adhesives

PubMed Central

Stewart, Russell J.; Wang, Ching Shuen; Shao, Hui

2011-01-01

Complex coacervation was proposed to play a role in the formation of the underwater bioadhesive of the Sandcastle worm (Phragmatopoma californica) based on the polyacidic and polybasic nature of the glue proteins and the balance of opposite charges at physiological pH. Morphological studies of the secretory system suggested the natural process does not involve complex coacervation as commonly defined. The distinction may not be important because electrostatic interactions likely play an important role in formation of the sandcastle glue. Complex coacervation has also been invoked in the formation of adhesive underwater silk fibers of caddisfly larvae and the adhesive plaques of mussels. A process similar to complex coacervation, that is, condensation and dehydration of biopolyelectrolytes through electrostatic associations, seems plausible for the caddisfly silk. This much is clear, the sandcastle glue complex coacervation model provided a valuable blueprint for the synthesis of a biomimetic, waterborne, underwater adhesive with demonstrated potential for repair of wet tissue. PMID:21081223

Precoding based channel prediction for underwater acoustic OFDM

NASA Astrophysics Data System (ADS)

Cheng, En; Lin, Na; Sun, Hai-xin; Yan, Jia-quan; Qi, Jie

2017-04-01

The life duration of underwater cooperative network has been the hot topic in recent years. And the problem of node energy consuming is the key technology to maintain the energy balance among all nodes. To ensure energy efficiency of some special nodes and obtain a longer lifetime of the underwater cooperative network, this paper focuses on adopting precoding strategy to preprocess the signal at the transmitter and simplify the receiver structure. Meanwhile, it takes into account the presence of Doppler shifts and long feedback transmission delay in an underwater acoustic communication system. Precoding technique is applied based on channel prediction to realize energy saving and improve system performance. Different precoding methods are compared. Simulated results and experimental results show that the proposed scheme has a better performance, and it can provide a simple receiver and realize energy saving for some special nodes in a cooperative communication.

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

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.

Randomised clinical trial of chest drainage systems.

PubMed Central

Graham, A N; Cosgrove, A P; Gibbons, J R; McGuigan, J A

1992-01-01

BACKGROUND: Problems in the management of thoracic trauma have stimulated the search for an alternative to underwater seals for drainage of the pleural cavity. A chest drainage bag incorporating a one way flutter valve has been compared with underwater seal drains in a randomised clinical trial. METHODS: During June-December 1989 119 patients undergoing elective thoracotomy were randomised to receive postoperative chest drainage by drainage bags (56 patients, 87 drains) or by underwater seal drains (63 patients, 98 drains). Daily drainage volumes, the requirement for pleural suction, mobility, and complications were recorded prospectively. RESULTS: There was no significant difference between the two groups in the mean volume drained, the requirements for pleural suction, or the occurrence of complications. Patients with drainage bags were fully mobile 23 hours (95% confidence interval 0-47 hours) earlier than the others. CONCLUSIONS: When used after elective thoracotomy drainage bags are safe and effective and permit earlier mobility than underwater seal drains. PMID:1496507

Monitoring Coral Growth - the Dichotomy Between Underwater Photogrammetry and Geodetic Control Network

NASA Astrophysics Data System (ADS)

Neyer, F.; Nocerino, E.; Gruen, A.

2018-05-01

Creating 3-dimensional (3D) models of underwater scenes has become a common approach for monitoring coral reef changes and its structural complexity. Also in underwater archeology, 3D models are often created using underwater optical imagery. In this paper, we focus on the aspect of detecting small changes in the coral reef using a multi-temporal photogrammetric modelling approach, which requires a high quality control network. We show that the quality of a good geodetic network limits the direct change detection, i.e., without any further registration process. As the photogrammetric accuracy is expected to exceed the geodetic network accuracy by at least one order of magnitude, we suggest to do a fine registration based on a number of signalized points. This work is part of the Moorea Island Digital Ecosystem Avatar (IDEA) project that has been initiated in 2013 by a group of international researchers (https://mooreaidea.ethz.ch/).

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

Li, Huidong; Deng, Zhiqun; Carlson, Thomas J.

Piezoelectric materials have been used in underwater acoustic transducers for nearly a century. In this paper, we reviewed four different types of piezoelectric materials: piezoelectric ceramics, single crystals, composites, and polymers, which are widely used in underwater acoustic transducers nowadays. Piezoelectric ceramics are the most dominant material type and are used as a single-phase material or one of the end members in composites. Piezoelectric single crystals offer outstanding electromechanical response but are limited by their manufacturing cost. Piezoelectric polymers provide excellent acoustic impedance matching and transducer fabrication flexibility although their piezoelectric properties are not as good as ceramics and singlemore » crystals. Composites combined the merits of ceramics and polymers and are receiving increased attention. The typical structure and electromechanical properties of each type of materials are introduced and discussed with respect to underwater acoustic transducer applications. Their advantages and disadvantages are summarized. Some of the critical design considerations when developing underwater acoustic transducers with these materials are also touched upon.« less

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.

Performance analysis of underwater pump for water-air dual-use engine

NASA Astrophysics Data System (ADS)

Xia, Jun; Wang, Yun; Chen, Yu

2017-10-01

To make water-air dual-use engine work both in air and under water, the compressor of the engine should not only meet the requirements of air flight, but also must have the ability to work underwater. To verify the performance of the compressor when the water-air dual-use engine underwater propulsion mode, the underwater pumping water model of the air compressor is simulated by commercial CFD software, and the flow field analysis is carried out. The results show that conventional air compressors have a certain ability to work in the water environment, however, the blade has a great influence on the flow, and the compressor structure also affects the pump performance. Compressor can initially take into account the two modes of water and air. In order to obtain better performance, the structure of the compressor needs further improvement and optimization.

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.

Noise and range considerations for close-range radar sensing of life signs underwater.

PubMed

Hafner, Noah; Lubecke, Victor

2011-01-01

Close-range underwater sensing of motion-based life signs can be performed with low power Doppler radar and ultrasound techniques. Corresponding noise and range performance trade-offs are examined here, with regard to choice of frequency and technology. The frequency range examined includes part of the UHF and microwave spectrum. Underwater detection of motion by radar in freshwater and saltwater are demonstrated. Radar measurements exhibited reduced susceptibility to noise as compared to ultrasound. While higher frequency radar exhibited better signal to noise ratio, propagation was superior for lower frequencies. Radar detection of motion through saltwater was also demonstrated at restricted ranges (1-2 cm) with low power transmission (10 dBm). The results facilitate the establishment of guidelines for optimal choice in technology for the underwater measurement motion-based life signs, with respect to trade offs involving range and noise.

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.

An underwater optical wireless communication system based on LED source

NASA Astrophysics Data System (ADS)

Rao, Jionghui; Wei, Wei; Wang, Feng; Zhang, Xiaohui

2011-11-01

Compared with other communication methods, optical wireless communication (OWC) holds the merits of higher transmitting rate and sufficient secrecy. So it is an efficacious communicating measure for data transmitting between underwater carriers. However, due to the water attenuation and the transmitter & the receiver (TX/RX) collimation, this application is restrained in underwater mobile carriers. A prototype for underwater OWC was developed, in which a high-powered green LED array was used as the light source which partly raveled the TX/RX collimation out. A small pumped-multiple-tube (PMT) was used as the detector to increase the communicating range, and FPGA chips were employed to code and decode the communicating data. The data rate of the prototype approached to 4 Mb/s at 8.4m and 1 Mb/s at 22m where voice and Morse communications were achieved in a scope of 30 degree TX/RX angle.

Attenuation of low-frequency underwater sound using an array of air-filled balloons and comparison to effective medium theory.

PubMed

Lee, Kevin M; Wilson, Preston S; Wochner, Mark S

2017-12-01

The ultimate goal of this work is to accurately predict the attenuation through a collection of large (on the order of 10-cm-radius) tethered encapsulated bubbles used in underwater noise abatement systems. Measurements of underwater sound attenuation were performed during a set of lake experiments, where a low-frequency compact electromechanical sound source was surrounded by different arrays of encapsulated bubbles with various individual bubbles sizes and void fractions. The measurements were compared with an existing predictive model [Church, J. Acoust. Soc. Am. 97, 1510-1521 (1995)] of the dispersion relation for linear propagation in liquid containing encapsulated bubbles. Although the model was originally intended to describe ultrasound contrast agents, it is evaluated here for large bubbles, and hence low frequencies, as a design tool for future underwater noise abatement systems, and there is good quantitative agreement between the observations and the model.

Localization of an Underwater Control Network Based on Quasi-Stable Adjustment.

PubMed

Zhao, Jianhu; Chen, Xinhua; Zhang, Hongmei; Feng, Jie

2018-03-23

There exists a common problem in the localization of underwater control networks that the precision of the absolute coordinates of known points obtained by marine absolute measurement is poor, and it seriously affects the precision of the whole network in traditional constraint adjustment. Therefore, considering that the precision of underwater baselines is good, we use it to carry out quasi-stable adjustment to amend known points before constraint adjustment so that the points fit the network shape better. In addition, we add unconstrained adjustment for quality control of underwater baselines, the observations of quasi-stable adjustment and constrained adjustment, to eliminate the unqualified baselines and improve the results' accuracy of the two adjustments. Finally, the modified method is applied to a practical LBL (Long Baseline) experiment and obtains a mean point location precision of 0.08 m, which improves by 38% compared with the traditional method.

Localization of an Underwater Control Network Based on Quasi-Stable Adjustment

PubMed Central

Chen, Xinhua; Zhang, Hongmei; Feng, Jie

2018-01-01

There exists a common problem in the localization of underwater control networks that the precision of the absolute coordinates of known points obtained by marine absolute measurement is poor, and it seriously affects the precision of the whole network in traditional constraint adjustment. Therefore, considering that the precision of underwater baselines is good, we use it to carry out quasi-stable adjustment to amend known points before constraint adjustment so that the points fit the network shape better. In addition, we add unconstrained adjustment for quality control of underwater baselines, the observations of quasi-stable adjustment and constrained adjustment, to eliminate the unqualified baselines and improve the results’ accuracy of the two adjustments. Finally, the modified method is applied to a practical LBL (Long Baseline) experiment and obtains a mean point location precision of 0.08 m, which improves by 38% compared with the traditional method. PMID:29570627

The influence of sea ice, wind speed and marine mammals on Southern Ocean ambient sound.

PubMed

Menze, Sebastian; Zitterbart, Daniel P; van Opzeeland, Ilse; Boebel, Olaf

2017-01-01

This paper describes the natural variability of ambient sound in the Southern Ocean, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by Antarctic blue whales ( Balaenoptera musculus intermedia ), fin whales ( Balaenoptera physalus ), Antarctic minke whales ( Balaenoptera bonaerensis ) and leopard seals ( Hydrurga leptonyx ). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The Antarctic blue and fin whale contributions were loudest in austral autumn, whereas the Antarctic minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.

Supercavitating flow around high-speed underwater projectile near free surface induced by air entrainment

NASA Astrophysics Data System (ADS)

Xu, Chang; Huang, Jian; Wang, Yiwei; Wu, Xiaocui; Huang, Chenguang; Wu, Xianqian

2018-03-01

Cavitating flow near free surface is a complicated issue and may provide new inspiration on high-speed surface cruising. This study observes stable supercavitating flow as a new phenomenon in a launch experiment of axisymmetric projectile when the upper side of the projectile coincides with the free surface. A numerical approach is established using large eddy-simulation and volume-of-fluid methods, and good agreements are achieved between numerical and experimental results. Supercavity formation mechanism is revealed by analyzing the experiment photographs and the iso-surface of 90% water volume fraction in numerical results. The entrainment of a large amount of air into the cavity can cause the pressure inside the cavity to similarly increase with the pressure outside the cavity, which makes the actual cavitation number close to zero and is similar to supercavitation. Cases with various headforms of the projectile and cavitation numbers on the cavitating flow, as well as the drag reduction effects are further examined. Results indicate that the present strategy near the free surface could possibly be a new effective approach for high-speed cruising after vigorous design optimization in the future.

Digital Learning Network Education Events of NASA's Extreme Environments Mission Operations

NASA Technical Reports Server (NTRS)

Paul, Heather; Guillory, Erika

2007-01-01

NASA's Digital Learning Network (DLN) reaches out to thousands of students each year through video conferencing and web casting. The DLN has created a series of live education videoconferences connecting NASA s Extreme Environment Missions Operations (NEEMO) team to students across the United States. The programs are also extended to students around the world live web casting. The primary focus of the events is the vision for space exploration. During the programs, NEEMO Crewmembers including NASA astronauts, engineers and scientists inform and inspire students about the importance of exploration and share the impact of the project as it correlates with plans to return to the moon and explore the planet Mars. These events highlight interactivity. Students talk live with the aquanauts in Aquarius, the National Oceanic and Atmospheric Administration s underwater laboratory. With this program, NASA continues the Agency s tradition of investing in the nation's education programs. It is directly tied to the Agency's major education goal of attracting and retaining students in science, technology, and engineering disciplines. Before connecting with the aquanauts, the students conduct experiments of their own designed to coincide with mission objectives. This paper describes the events that took place in September 2006.

Near-specular acoustic scattering from a buried submarine mud volcano.

PubMed

Gerig, Anthony L; Holland, Charles W

2007-12-01

Submarine mud volcanoes are objects that form on the seafloor due to the emission of gas and fluidized sediment from the Earth's interior. They vary widely in size, can be exposed or buried, and are of interest to the underwater acoustics community as potential sources of active sonar clutter. Coincident seismic reflection data and low frequency bistatic scattering data were gathered from one such buried mud volcano located in the Straits of Sicily. The bistatic data were generated using a pulsed piston source and a 64-element horizontal array, both towed over the top of the volcano. The purpose of this work was to appropriately model low frequency scattering from the volcano using the bistatic returns, seismic bathymetry, and knowledge of the general geoacoustic properties of the area's seabed to guide understanding and model development. Ray theory, with some approximations, was used to model acoustic propagation through overlying layers. Due to the volcano's size, scattering was modeled using geometric acoustics and a simple representation of volcano shape. Modeled bistatic data compared relatively well with experimental data, although some features remain unexplained. Results of an inversion for the volcano's reflection coefficient indicate that it may be acoustically softer than expected.

Eutrophication monitoring for Lake Superior's Chequamegon ...

EPA Pesticide Factsheets

A priority for the Lake Superior CSMI was to identify susceptible nearshore eutrophication areas. We developed an integrated sampling design to collect baseline data for Lake Superior’s Chequamegon Bay to understand how nearshore physical processes and tributary loading relate to observed chlorophyll concentrations. Sampling included ship-based water samples combined with vertical CTD casts, continuous in situ towing and data collected from an autonomous underwater glider. Sampling was conducted during June, July and September. The glider collected regional data as part of three extended missions in Lake Superior over the same periods. During the study, two significant storm events impacted the western end of Lake Superior; the first occurred during July 11-12, with 8-10 inches of rain in 24hrs, and the second on July 21 with winds in excess of 161 km/h. Using GIS software, we organized these diverse temporal data sets along a continuous time line with temporally coincident Modis Satellite data to visualize surface sediment plumes in relation to water quality measurements. Preliminary results suggest that both events impacted regional water quality, and that nearshore physical forces (upwelling and currents) influenced the spatial variability. Results comparing in situ measures with remotely sensed images will be discussed. not applicable

The influence of sea ice, wind speed and marine mammals on Southern Ocean ambient sound

NASA Astrophysics Data System (ADS)

Menze, Sebastian; Zitterbart, Daniel P.; van Opzeeland, Ilse; Boebel, Olaf

2017-01-01

This paper describes the natural variability of ambient sound in the Southern Ocean, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by Antarctic blue whales (Balaenoptera musculus intermedia), fin whales (Balaenoptera physalus), Antarctic minke whales (Balaenoptera bonaerensis) and leopard seals (Hydrurga leptonyx). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The Antarctic blue and fin whale contributions were loudest in austral autumn, whereas the Antarctic minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.

Inverse Flux versus Pressure of Muons from Cosmic Rays

NASA Astrophysics Data System (ADS)

Buitrago, D.; Armendariz, R.

2017-12-01

When an incoming cosmic ray proton or atom collides with particles in earth's atmosphere a shower of secondary muons is created. Cosmic ray muon flux was measured at the Queensborough Community College using a QuarkNet detector consisting of three stacked scintillator muon counters and a three-fold coincidence trigger. Data was recorded during a three-day period during a severe weather storm that occurred from March 13-17, 2017. A computer program was created in Python to read the muon flux rate and atmospheric pressure sensor readings from the detector's data acquisition board. The program converts the data from hexadecimal to decimal, re-bins the data in a more suitable format, creates and overlays plots of muon flux with atmospheric pressure. Results thus far show a strong correlation between muon flux and atmospheric pressure. More data analysis will be done to verify the above conclusion.

Demonstration of clomipramine and venlafaxine occupation at serotonin reuptake sites in man in vivo.

PubMed

Malizia, A L; Melichar, J M; Brown, D J; Gunn, R N; Reynolds, A; Jones, T; Nutt, D J

1997-01-01

We describe the use of 11CRTI-55 and the Multiple Objects Coincidences Counter (MOCC) to detect in-vivo binding to peripheral serotonin reuptake sites (left chest comprising platelet and lung serotonin reuptake sites) in man. Displacement and preloading experiments with clomipramine and venlafaxine in two healthy volunteers demonstrated that 11CRTI-55 binding is decreased in a dose-dependent fashion by both these drugs which bind to the serotonin transporter. In addition parallel data from the total head curve (representing 11CRTI-55 binding to central serotonin and dopamine (DA) reuptake sites) suggest that prior blockade of the serotonin transporter may be a useful strategy to maximize radioactive counts in the head when measuring the DA transporter. The MOCC is likely to be useful to determine sequential indices of relative serotonin reuptake blockade in patients on treatment.

Results of the CCRI(II)-S12.H-3 supplementary comparison: Comparison of methods for the calculation of the activity and standard uncertainty of a tritiated-water source measured using the LSC-TDCR method.

PubMed

Cassette, Philippe; Altzitzoglou, Timotheos; Antohe, Andrei; Rossi, Mario; Arinc, Arzu; Capogni, Marco; Galea, Raphael; Gudelis, Arunas; Kossert, Karsten; Lee, K B; Liang, Juncheng; Nedjadi, Youcef; Oropesa Verdecia, Pilar; Shilnikova, Tanya; van Wyngaardt, Winifred; Ziemek, Tomasz; Zimmerman, Brian

2018-04-01

A comparison of calculations of the activity of a 3 H 2 O liquid scintillation source using the same experimental data set collected at the LNE-LNHB with a triple-to-double coincidence ratio (TDCR) counter was completed. A total of 17 laboratories calculated the activity and standard uncertainty of the LS source using the files with experimental data provided by the LNE-LNHB. The results as well as relevant information on the computation techniques are presented and analysed in this paper. All results are compatible, even if there is a significant dispersion between the reported uncertainties. An output of this comparison is the estimation of the dispersion of TDCR measurement results when measurement conditions are well defined. Copyright © 2017 Elsevier Ltd. All rights reserved.

Russian-US collaboration on implementation of the active well coincidence counter (AWCC)

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

Mozhajev, V.; Pshakin, G.; Stewart, J.

The feasibility of using a standard AWCC at the Obninsk IPPE has been demonstrated through active measurements of single UO{sub 2} (36% enriched) disks and through passive measurements of plutonium metal disks used for simulating reactor cores. The role of the measurements is to verify passport values assigned to the disks by the facility, and thereby facilitate the mass accountability procedures developed for the very large inventory of fuel disks at the facility. The AWCC is a very flexible instrument for verification measurements of the large variety of nuclear material items at the Obninsk IPPE and other Russian facilities. Futuremore » work at the IPPE will include calibration and verification measurements for other materials, both in individual disks and in multi-disk storage tubes; it will also include training in the use of the AWCC.« less

Total prompt γ-ray emission in fission

NASA Astrophysics Data System (ADS)

Wu, C. Y.; Chyzh, A.; Kwan, E.; Henderson, R. A.; Bredeweg, T. A.; Haight, R. C.; Hayes-Sterbenz, A. C.; Lee, H. Y.; O'Donnell, J. M.; Ullmann, J. L.

2017-09-01

The total prompt γ-ray energy distributions were measured for the neutron-induced fission of 235U, 239,241Pu at incident neutron energy of 0.025 eV-100 keV, and the spontaneous fission of 252Cf using the Detector for Advanced Neutron Capture Experiments (DANCE) array in coincidence with the detection of fission fragments by a parallel-plate avalanche counter. Corrections were made to the measured distribution by unfolding the two-dimension spectrum of total prompt γ-ray energy vs multiplicity using a simulated DANCE response matrix. A summary of this work is presented with the emphasis on the comparison of total prompt fission γ-ray energy between our results and previous ones. The mean values of the total prompt γ-ray energy ⟨Eγ,tot⟩, determined from the unfolded distributions, are ˜20% higher than those derived from measurements using single γ-ray detector for all the fissile nuclei studied.

Cosmic ray scintillations in the frequency range from 0.00001 to 0.01 Hz

NASA Technical Reports Server (NTRS)

Gehrels, N.; Lheureux, J.

1978-01-01

Power spectra of the flux variations in cosmic rays of energy greater than a few GeV are presented. The data were obtained at balloon altitudes (40-45 km) from two scintillation-type detectors flown for six hours from Palestine, Texas, on November 4, 1972. The large area detectors had effective count rates up to 2000 cps setting the Poisson noise level in the power spectra of the relative fluctuations at 0.001/Hz. The analysis was made on the singles rate of each of the counters as well as on the coincidence rates between them. In all cases, the spectra between 0.0001 and 0.002 Hz are power laws in frequency of the form f to the exponent negative gamma, where gamma is between 1.5 and 2.0. No significant peaks in the range 0.0001 to 0.01 Hz are observed.

A Wide Area Risk Assessment Framework for Underwater Military Munitions Response

NASA Astrophysics Data System (ADS)

Holland, K. T.; Calantoni, J.

2017-12-01

Our objective was to develop a prototype statistical framework supporting Wide Area Assessment and Remedial Investigation decisions relating to the risk of unexploded ordnance and other military munitions concentrated in underwater environments. Decision making involving underwater munitions is inherently complex due to the high degree of uncertainty in the environmental conditions that force munitions responses (burial, decay, migration, etc.) and associated risks to the public. The prototype framework provides a consistent approach to accurately delineating contaminated areas at underwater munitions sites through the estimation of most probable concentrations. We adapted existing deterministic models and environmental data services for use within statistical modules that allowed the estimation of munition concentration given historic site information and environmental attributes. Ultimately this risk surface can be used to evaluate costs associated with various remediation approaches (e.g. removal, monitoring, etc.). Unfortunately, evaluation of the assessment framework was limited due to the lack of enduser data services from munition site managers. Of the 450 U.S. sites identified as having potential contamination with underwater munitions, assessment of available munitions information (including historic firing or disposal records, and recent ground-truth munitions samples) indicated very limited information in the databases. Example data types include the most probable munition types, approximate firing / disposal dates and locations, and any supportive munition survey or sampling results. However the overall technical goal to integrate trained statistical belief networks with detailed geophysical knowledge of sites, of sensors and of the underwater environment was demonstrated and should allow probabilistic estimates of the most likely outcomes and tradeoffs while managing uncertainty associated with military munitions response.

Roles of individual radicals generated by a submerged dielectric barrier discharge plasma reactor during Escherichia coli O157:H7 inactivation

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

Khan, Muhammad Saiful Islam; Lee, Eun-Jung; Kim, Yun-Ji, E-mail: yunji@kfri.re.kr

A submerged dielectric barrier discharge plasma reactor (underwater DBD) has been used on Escherichia coli O157:H7 (ATCC 35150). Plasma treatment was carried out using clean dry air gas to investigate the individual effects of the radicals produced by underwater DBD on an E. coli O157:H7 suspension (8.0 log CFU/ml). E. coli O157:H7 was reduced by 6.0 log CFU/ml for 2 min of underwater DBD plasma treatment. Optical Emission Spectra (OES) shows that OH and NO (α, β) radicals, generated by underwater DBD along with ozone gas. E. coli O157:H7 were reduced by 2.3 log CFU/ml for 10 min of underwatermore » DBD plasma treatment with the terephthalic acid (TA) OH radical scavenger solution, which is significantly lower (3.7 log CFU/ml) than the result obtained without using the OH radical scavenger. A maximum of 1.5 ppm of ozone gas was produced during the discharge of underwater DBD, and the obtained reduction difference in E.coli O157:H7 in presence and in absence of ozone gas was 1.68 log CFU/ml. The remainder of the 0.62 log CFU/ml reduction might be due to the effect of the NO (α, β) radicals or due to the combined effect of all the radicals produced by underwater DBD. A small amount of hydrogen peroxide was also generated but does not play any role in E. coli O157:H7 inactivation.« less

Acoustic characteristics of underwater tail slaps used by Norwegian and Icelandic killer whales (Orcinus orca) to debilitate herring (Clupea harengus).

PubMed

Simon, Malene; Wahlberg, Magnus; Ugarte, Fernando; Miller, Lee A

2005-06-01

Norwegian killer whales debilitate prey by slapping their tails into herring schools. These underwater tail slaps produce a thud-like sound. It is unclear whether this sound is caused by cavitation and/or physical contact between herring and whale tail. Also the forces causing debilitation of the fish are not understood. Here we present an acoustic analysis of underwater tail slaps using a multi-channel wide (150 kHz) band recording system. Underwater tail slaps produced by Norwegian killer whales generated sounds consisting of multiple pulses with source levels of 186+/-5.4 dB (pp) re.1 microPa at 1 m (+/-1 s.d., N = 4). The -3 dB and 97% energy bandwidths were 36.8+/-22.5 kHz and 130.5+/-17.5 kHz (+/-1 s.d., N = 13), respectively, with a centre frequency of 46.1+/-22.3 kHz. The similarities between the acoustic properties of underwater tail slaps recorded from killer whales in Norway, and thud-like sounds recorded from killer whales in Iceland suggest that Norwegian and Icelandic killer whales use similar hunting techniques. The acoustic characteristics of sounds produced by underwater tail slaps were similar to the ones from other cavitation sound sources described in the literature, both in term of temporal and frequency features as well as in source level. We suggest that multiple factors generated by the tail slaps like particle fluctuations, turbulence, pressure changes and physical impact cause debilitation of herring.

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...

Prioritizing bridge structures for underwater inspections : summary report.

DOT National Transportation Integrated Search

1993-01-01

In the last decade, there has been increasing national concern about the adequacy of underwater inspection of bridge substructures. A number of factors have contributed to this concern, in particular the collapse of several major spans, some of which...

Communication and cooperation in underwater acoustic networks

NASA Astrophysics Data System (ADS)

Yerramalli, Srinivas

In this thesis, we present a study of several problems related to underwater point to point communications and network formation. We explore techniques to improve the achievable data rate on a point to point link using better physical layer techniques and then study sensor cooperation which improves the throughput and reliability in an underwater network. Robust point-to-point communications in underwater networks has become increasingly critical in several military and civilian applications related to underwater communications. We present several physical layer signaling and detection techniques tailored to the underwater channel model to improve the reliability of data detection. First, a simplified underwater channel model in which the time scale distortion on each path is assumed to be the same (single scale channel model in contrast to a more general multi scale model). A novel technique, which exploits the nature of OFDM signaling and the time scale distortion, called Partial FFT Demodulation is derived. It is observed that this new technique has some unique interference suppression properties and performs better than traditional equalizers in several scenarios of interest. Next, we consider the multi scale model for the underwater channel and assume that single scale processing is performed at the receiver. We then derive optimized front end pre-processing techniques to reduce the interference caused during single scale processing of signals transmitted on a multi-scale channel. We then propose an improvised channel estimation technique using dictionary optimization methods for compressive sensing and show that significant performance gains can be obtained using this technique. In the next part of this thesis, we consider the problem of sensor node cooperation among rational nodes whose objective is to improve their individual data rates. We first consider the problem of transmitter cooperation in a multiple access channel and investigate the stability of the grand coalition of transmitters using tools from cooperative game theory and show that the grand coalition in both the asymptotic regimes of high and low SNR. Towards studying the problem of receiver cooperation for a broadcast channel, we propose a game theoretic model for the broadcast channel and then derive a game theoretic duality between the multiple access and the broadcast channel and show that how the equilibria of the broadcast channel are related to the multiple access channel and vice versa.

Thermotropic Liquid Crystal Film Underwater

NASA Astrophysics Data System (ADS)

Uto, Sadahito; Nakanishi, Yuuji; Matsumoto, Takahumi

2005-05-01

A thermotropic liquid crystal film was produced in distilled water successfully. A lecithin suspension was utilized to make the film. Polarizing microscopic observations were carried out. The molecular arrangement was seemed to be homeotoropic. An expected electrooptic response of the film underwater was confirmed.

An investigation of underwater sound propagation from pile driving.

DOT National Transportation Integrated Search

2011-12-01

The underwater noise from impact pile driving was studied by using a finite element model for the sound generation and a parabolic equation model for propagation. Results were compared with measurements taken with a vertical line array deployed durin...

Astronaut Bobko assists Astronaut Peterson prior to underwater training

NASA Technical Reports Server (NTRS)

1982-01-01

Astronaut Karol J. Bobko, left, STS-6 pilot, assists Astronaut Donald H. Peterson, STS-6 mission specialist, prior to underwater training session in the weightless environment training facility. Peterson is wearing the extravehicular mobility unit minus the helmet and gloves.