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Engineering in the Ocean Environment, Ocean 72 - IEEE International Conference on

Date 13-15 Sept. 1972

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Displaying Results 1 - 25 of 126
  • [Front cover and table of contents]

    Publication Year: 1972 , Page(s): 0
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  • Foreword

    Publication Year: 1972 , Page(s): 0
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    Freely Available from IEEE
  • [Back cover]

    Publication Year: 1972 , Page(s): 0
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    Freely Available from IEEE
  • Ocean engineering

    Publication Year: 1972 , Page(s): 2
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  • The economics of ocean exploration

    Publication Year: 1972 , Page(s): 3 - 4
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  • Numerical models: A tool for investigating ocean circulation

    Publication Year: 1972 , Page(s): 5 - 6
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    An increasing need exists for quantitative studies of the circulation of the world ocean. The hydrodynamic equations with a suitable Reynolds averaging to eliminate very Small scale motion may be used to analyze the very extensive data on the temperature and salinity structure of the ocean which have been gathered by oceanographic expeditions. Hydrodynamic models may also be useful in planning future surveys as well as predicting the formation of large scale temperature anomalies in the ocean which are believed to be an important influence on world fisheries and year to year variations in weather. View full abstract»

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  • Probability models of received scattered and ambient fields

    Publication Year: 1972 , Page(s): 8 - 14
    Cited by:  Papers (7)
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    With the aid of the appropriate statistical-physical models of underwater scattering and ambient field generation, explicit first-, second-, and higher-order probability distributions of such fields as they appear in a typical receiver can be constructed. The lower-order distributions, at least, are analytically tractable, and thereby provide working statistical representations of an important class of nongaussian channels. Similar statistical-physical models can be constructed for other, broad classes of nonnormal channels, such as those produced by atmospherics, seismic disturbances, and man-made electromagnetic and acoustical interference. These models are based on a poisson distribution of (primary or scatter) sources in the medium or the given domain. For example, in an ocean or lake environment this corresponds to the usual condition of dominant primary radiation, or scattering in the medium or at its interfaces; equivalently for manmade interference, this reflects the inherently independent emissive properties of the sources involved. Here, the general approach is very briefly outlined and a number of specific results, typical of these phenomena generally, are presented. View full abstract»

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  • Detection of underwater signals in reverberation limited noise: A specific example on the effects of non-zero velocity gradients

    Publication Year: 1972 , Page(s): 15 - 24
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    An example is given to demonstrate the utility and importance of a generalized theory of acoustic signal detection in reverberation-limited noise. The theory treats the significant influences of geometry and physics on the structure and performance of Bayes detectors. View full abstract»

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  • Optimum signal and filter design in underwater acoustic echo ranging system

    Publication Year: 1972 , Page(s): 25 - 30
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    Multipath and reverberation effects in the sonar environment are analyzed in this study. The maximization of the output signal-to-interference ratio is used as a performance criterion which reduces the optimization problem to the solution of a pair of linear integral equations with the largest eigenvalue. View full abstract»

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  • On the efficient processing of sonar signals

    Publication Year: 1972 , Page(s): 31 - 33
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    Techniques for processing active sonar signals using Fourier and Walsh transforms are discussed. A method is introduced which uses the Walsh-Hadamard transform and permits excellent processing economy. This economy plus the observed ability of the resultant processor to maintain quality estimation of target range and range rate may make this system quite practical for certain sonar detection applications. View full abstract»

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  • An experiment in high rate underwater telemetry

    Publication Year: 1972 , Page(s): 34 - 38
    Cited by:  Papers (10)  |  Patents (1)
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    A project is described which explores the feasibility of high rate telemetry over the short range (< 10 km) underwater acoustic channel. An experimental digital signal generator was constructed to provide a variety of modulations for evaluation. A frequency-hopping signalling format of 2.5 kHz bandwidth was chosen with simultaneous FSK and PSK modulation. Several operating modes with transmission rates from 138 to 1640 bits/s were tested at sea. Analysis of the sea test data to date has shown both the FSK and the PSK modulations to be readable, indicating that high rate telemetry can be realized with this signalling format. View full abstract»

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  • A new coding scheme for noisy channel

    Publication Year: 1972 , Page(s): 39 - 42
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    In this paper a new coding scheme is presented, which is coded by interleving two code blocks of an independent error correcting code, which exsist \ell - blocks apart, in order to improve error correcting ability of each block. The class of codes is especially effective for very noisy channel which contains both independent errors and burst errors by analysis of block error probability using modified Gilbert's burst noise channel model. And this coding scheme has no error propagation which is often seen in the general recurrent codes. View full abstract»

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  • Amplitude measurement technique for low duty cycle acoustic signals

    Publication Year: 1972 , Page(s): 43 - 46
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    A method of measuring the mean rms level of a low duty cycle acoustic signal using an inverting circuit and an integrating digital voltmeter (DVM) is described. The technique has the capability of taking many measurements which are recorded, in one configuration, through a data coupler on paper tape for analysis on a time share computer. The important system characteristics are noted and an estimate of the system error is tabulated. View full abstract»

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  • Tidal energy and its development

    Publication Year: 1972 , Page(s): 48 - 56
    Cited by:  Papers (2)
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    In writing about tidal energy it is simple enough to chronicle the history of attempts to generate it, starting with the medieval tidal mills of Western Europe and examining some of the many ingenious ideas which have been propounded by engineering writers from many countries since then. View full abstract»

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  • Acoustic assessment of salmon at sea for the purpose of run prediction

    Publication Year: 1972 , Page(s): 58 - 60
    Cited by:  Papers (1)
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    Investigations into the migratory habits of salmon have shown that population sampling in particular areas of the North Pacific can help to predict the spawning migration to Bristol Bay, Alaska, the succeeding year. This population indexing has been done with standard purse-seining gear operated at a fixed series of stations. Such indices of population size have proved useful to both the fishing industry and the management agencies in planning their respective operations. This paper describes an acoustic sampling system developed at the University of Washington which will be used to help index this salmon population. View full abstract»

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  • A method for extracting the fish target strength distribution from acoustic echoes

    Publication Year: 1972 , Page(s): 61 - 64
    Cited by:  Papers (12)
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    Fisheries biologists using acoustic stock assessment systems need a signal processor that will provide an estimate of the fish target strength density function. The estimated density function can be used by the biologist to determine the fish size distribution within the surveyed population and to Convert the output of an echo integrator into a density estimate. A method for extracting the target strength density function from the acoustic pulses reflected from the fish is described in this paper. The results of a Monte Carlo simulation of the technique are presented. View full abstract»

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  • Biologically produced acoustical signals in an estuary

    Publication Year: 1972 , Page(s): 65 - 68
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    Two field trips were made to the Barataria Bay area in the fall of 1971. On each trip several excursions were made out in the estuaries to determine the ambient noise levels at various locations. The data was analyzed to determine the power spectra; and the relative acoustic activity was correlated with known oceanographical parameters. View full abstract»

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  • An 8-Channel, ultrasonic, marine bio-telemetry transmitter utilizing C/MOS digital integrated circuits

    Publication Year: 1972 , Page(s): 69 - 77
    Cited by:  Papers (2)
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    Up to 8 multiplexed channels of shark behaviorial data at sea are obtained with a 40 KHz acoustic transmitter with a range exceeding 5 km and a life of up to 1 week. Conservation of battery power is achieved with complementary metal-oxide semiconductor (C/MOS) integrated circuits and a pulse-interval data format of 10 ms pulses at intervals between 200 ms and 2 sec. A multivibrator oscillator is used to control the operating frequency which is essentially independent of temperature and pressure, and decreases slightly with battery voltage (<800 Hz/ 2-volt drop). An optional crystal oscillator maintains constant frequency. The pulse repetition rate is not significantly affected by voltage, pressure, and temperature. Fail safe devices ensure operation in the event of sensor or multiplexer failure. View full abstract»

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  • A facility for testing remote sensing systems for fisheries use

    Publication Year: 1972 , Page(s): 78 - 82
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    The paper discusses initiation of National Oceanic and Atmospheric Administration/National Marine Fisheries Service's Program, Mississippi Test Facility, Bay St. Louis, Mississippi, to accelerate application of remote sensing to fisheries. Facility is designed to provide controlled biological environment in which tests can be conducted under near natural conditions. History of at-sea and tank tests conducted prior to establishment of the present facility is discussed; also, results gained from these efforts. Description of system's current configuration to support marine organisms under controlled conditions, limitations of system, because of its unique location and capabilities, includes testing of: 1) aerial remote sensors of fish and environmental parameters, 2) subsurface systems such as hydroacoustics and other subsurface techniques, and 3) detailed observations of marine species behavior under simulated conditions. Current activities include biological stabilization of system, effectiveness of recent tests, and planned experiments. View full abstract»

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  • The sanguine concept

    Publication Year: 1972 , Page(s): 84 - 87
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    The technical basis of Project Sanguine is outlined. This U. S. Navy-sponsored project has a stated objective to develop a world-wide communication system that can be used to send messages to submarines at operation depth. Until recently, the work has been shrouded in a cloak of secrecy. Attention is called to the fundamental electromagnetic propagation studief that preceded the 10-year engineering development of the system that has not yet been "validated''. Some of the recent widely publicized criticisms are put in perspective and various conclusions are drawn. View full abstract»

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  • From concept to system acquisition

    Publication Year: 1972 , Page(s): 88 - 90
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  • Sanguine system overview

    Publication Year: 1972 , Page(s): 91 - 94
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  • ELF communication system design

    Publication Year: 1972 , Page(s): 95 - 109
    Cited by:  Papers (1)
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    Radio waves of frequency below about 1 kHz propagate around the earth-ionosphere cavity with very little attenuation. These waves also can propagate useful distances down into the ocean. They are attractive therefore, for providing long-range communication to submarines from a single site. By considering the various components of the communication channel in turn, the paper develops the design principles for such a system. Significant features are the use of insulated horizontal dipoles, grounded at each end, as the antennas, an optimum operating frequency below 150 Hz, non-linear processing in the receiver to reduce the effective atmospheric noise, and the large size but sparse installation density of the transmitting antenna. View full abstract»

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  • ELF propagation measurements

    Publication Year: 1972 , Page(s): 110 - 113
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    An experimental measurement program has been conducted to determine parameters for propagation in the 40-50 and 70-80 Hz range. These measurements have utilized a transmitter in Wisconsin radiating approximately 0.25W at 45Hz and 0.5W at 75 Hz. Simple sinusoidal signals have been received and estimated at several sites, some on the same great circle path. Sites have been located in Nova Scotia, Utah, Hawaii, Norway, Greece and Saipan. Based on a simplified propagation model it has been possible to estimate attenuation rates and mode excitation factors with high accuracy subject to some constraints which are discussed. Both daytime and nighttime attenuation rates and excitation factors are discussed. View full abstract»

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  • ELF propagation using zonal harmoics

    Publication Year: 1972 , Page(s): 114 - 116
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