GLORIA

GEOMAR Library Ocean Research Information Access

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Comparative Studies. Non-European Languages/Literatures  (17)
  • 1
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2012
    In:  The Journal of the Acoustical Society of America Vol. 132, No. 3_Supplement ( 2012-09-01), p. 2094-2094
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 132, No. 3_Supplement ( 2012-09-01), p. 2094-2094
    Abstract: Increasing demands for high accuracy and rapid measurement of sound speed have prompted the development of portable sound velocimeter in oceanography. Generally, sound speed can be established by CTD or TD (Time Delayed) method respectively. CTD method suffers from errors of corresponding sensors and application range of the converting equations. TD method, sing-around technique representative, is widely used in portable velocimeter. The accuracy of TD is proportional to receiving SNR and signal length. The duration of tone burst in convenient sing-around is limited by multi-echo, thus only a few valid data can be utilized. To address the problems, DSSS (Direct-Sequence-Spread-Spectrum) signal in continuous form is adopted to extract the TD directly, with which sound speed could be established related to laboratory derived equations, Del Grosso’s equation representative. Based on this method, two separate transducers were deployed with constant distance. Cross-correlation between received and transmitted (orthogonal form) signals is computed. Combine Time-of-Flight and Phase-Shift, the TD can be derived by two processes, the peak detecting of cross-correlation envelope and carrier phase estimating. Theoretic analyses and experiments indicate that the accuracy with DSSS relates to the period of PN sequence, the frequency of chip, and the linearity characteristic of electronic circuits and transducers.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2012
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2021
    In:  The Journal of the Acoustical Society of America Vol. 149, No. 3 ( 2021-03-01), p. 1579-1588
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 149, No. 3 ( 2021-03-01), p. 1579-1588
    Abstract: Total harmonic distortion (THD) plays an important role in the performance of miniature loudspeakers used in mobile phones. Traditional nonlinear models fail to predict THD in the higher frequency domain. Significant discrepancies can be found between the prediction and measurement. In this study, an extended model considering nonlinear acoustic damping is proposed to address this issue. Flow separation occurring near the orifices of the sound port is of particular interest. Two velocity-dependent parameters were derived to model the nonlinear damping effect. Based on the extended model, the dynamics of miniature loudspeakers are described using the state-space method. Experiments and calculations confirm the validity of the extended model. The influence of nonlinear acoustic damping on THD is also discussed.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2021
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2010
    In:  The Journal of the Acoustical Society of America Vol. 127, No. 4 ( 2010-04-01), p. 2358-2367
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 127, No. 4 ( 2010-04-01), p. 2358-2367
    Abstract: Underwater acoustic orthogonal frequency division multiplexing (OFDM) enables simple frequency domain equalization, but its performance is often limited by intercarrier interference (ICI) that is induced by channel variation, in addition to the ambient noise. As the signal itself, the variance of the ICI is frequency dependent as (i) the transmitter often has a nonideal transmit voltage response (TVR) and (ii) underwater acoustic propagation introduces frequency dependent attenuation. In this paper, a simple method to account for the frequency dependent spectrum of the ICI plus noise is proposed. Specifically, the power spectrum of the ICI plus noise is approximated using a low-order polynomial in the log domain, by fitting the measurements on the null subcarriers embedded in each OFDM symbol. Prewhitening is then applied to each OFDM symbol before channel estimation and data demodulation. The proposed method is tested using experimental data collected from the SPACE08 and RACE08 experiments, where signals with and without transmitter precompensation are compared side by side in the former. Impressive performance gains are found whenever the signal is significantly colored. This is the case when either the TVR is not compensated or the transmission distance and bandwidth are large.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2010
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 1996
    In:  The Journal of the Acoustical Society of America Vol. 100, No. 4_Supplement ( 1996-10-01), p. 2593-2593
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 100, No. 4_Supplement ( 1996-10-01), p. 2593-2593
    Abstract: A computational model of the precedence effect is proposed by assuming that the precedence effect is caused by the inhibition of sound localization which depends on the estimated sound-to-echo ratio. It is found that a generalized pattern of impulse response with delay and decay features can be used for echo estimation. As a real neural implementation, the pattern of an after-effect in the human auditory system, based on the previous psychoacoustic just-noticeable-difference tests of interaural delay and intensity, is adopted. This pattern has delay and decay features similar to those in the generalized pattern of impulse response, and the difference in decay scales is shown to cause little difference in echo estimation. The results of psychoacoustic experiments, e.g., equal-level and unequal-level paired click tests [P. M. Zurek, J. Acoust. Soc. Am. 67, 952–964 (1980); K. Saberi and D. R. Perrott,ibid. 87, 1732–1737 (1990)] , Haas’s tests [H. Haas, J. Audio Eng. Soc. 20, 146–159 (1972)], Franssen’s tests [J. Blauert, Spatial Hearing (MIT, Cambridge, MA, 1983)] , and others, can be interpreted consistently. This model can also give criteria for an available onset and an explanation of why a transient onset is required for the precedence effect.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1996
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2006
    In:  The Journal of the Acoustical Society of America Vol. 119, No. 5_Supplement ( 2006-05-01), p. 3214-3215
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 119, No. 5_Supplement ( 2006-05-01), p. 3214-3215
    Abstract: We introduce acoustic imaging methods using wave-field downward continuation and describe their application to geophysical imaging and ultrasonic breast imaging. We have developed a number of novel migration imaging methods based on the acoustic-wave equation in heterogeneous media. They have been successfully applied for imaging complex structures beneath buried salt bodies in which the velocity is often more than twice that of the surrounding sediment within the Earth. The length scale in seismic imaging problems is on the order of 100 times of the seismic wavelength. Even though the frequency used in ultrasonic breast imaging is at a few megahertz, which is a million times higher than seismic frequency, its length scale is also on the order of 100 times of the ultrasonic wavelength in the breast. On the other hand, there are many differences between seismic imaging and ultrasonic breast imaging. For example, the sizes of imaging objects are 10–100 wavelengths for seismic imaging but on the order of the wavelength or less for ultrasonic breast imaging. We have successfully applied the wave-equation-based migration methods to ultrasonic breast imaging. We will present imaging examples both in seismic imaging and ultrasonic breast imaging.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2006
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2023
    In:  The Journal of the Acoustical Society of America Vol. 153, No. 3 ( 2023-03-01), p. 1626-1636
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 153, No. 3 ( 2023-03-01), p. 1626-1636
    Abstract: Sound projection is a method of using highly focused sources to project sound onto reflective surfaces to create the impression of surround sound, which can be realized via beamforming using loudspeaker arrays. Generally, these devices are mounted near a surface with a finite acoustic impedance, such as a TV accent wall. The beamforming performance degrades in this half-space with an impedance boundary when the filters are designed using transfer functions measured in the free field. This paper proposes a model for predicting the beamforming performance in a half-space with an impedance boundary in terms of the transfer functions in the free field. A mathematical model is presented, and the results are compared with practical measurements for a 16-driver line array in real-use environments. The results show that reflections from the boundary lead to “dark bands” in the beam, causing the beam to deviate from the designed direction. Using filters designed with transfer functions calculated by the proposed model yields improved beamforming performance.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2023
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    Online Resource
    Online Resource
    Elsevier BV ; 2023
    In:  Artificial Intelligence Vol. 323 ( 2023-10), p. 103986-
    In: Artificial Intelligence, Elsevier BV, Vol. 323 ( 2023-10), p. 103986-
    Type of Medium: Online Resource
    ISSN: 0004-3702
    RVK:
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 1468341-6
    detail.hit.zdb_id: 218797-8
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    Online Resource
    Online Resource
    Elsevier BV ; 2011
    In:  Brain and Language Vol. 117, No. 2 ( 2011-5), p. 77-87
    In: Brain and Language, Elsevier BV, Vol. 117, No. 2 ( 2011-5), p. 77-87
    Type of Medium: Online Resource
    ISSN: 0093-934X
    RVK:
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2011
    detail.hit.zdb_id: 1462477-1
    SSG: 5,2
    SSG: 7,11
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    In: Brain and Language, Elsevier BV, Vol. 104, No. 1 ( 2008-1), p. 10-23
    Type of Medium: Online Resource
    ISSN: 0093-934X
    RVK:
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2008
    detail.hit.zdb_id: 1462477-1
    SSG: 5,2
    SSG: 7,11
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    Online Resource
    Online Resource
    Elsevier BV ; 2003
    In:  Brain and Language Vol. 85, No. 3 ( 2003-6), p. 531-534
    In: Brain and Language, Elsevier BV, Vol. 85, No. 3 ( 2003-6), p. 531-534
    Type of Medium: Online Resource
    ISSN: 0093-934X
    RVK:
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2003
    detail.hit.zdb_id: 1462477-1
    SSG: 5,2
    SSG: 7,11
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...