The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform

Toshiyuki Shigemi - One of the best experts on this subject based on the ideXlab platform.

  • Design Loads Used for Direct Strength Assessment of Merchant Ship Structures
    Journal of Offshore Mechanics and Arctic Engineering, 2006
    Co-Authors: Tingyao Zhu, Toshiyuki Shigemi
    Abstract:

    This paper summarizes the results of extensive research on the design loads used for strength assessment of Merchant Ship structures such as tankers, bulk carriers, and container Ships. The main aim of the research was to develop practical estimation methods of design loads having rational technical backgrounds acting on primary structural members of tankers, bulk carriers, and container Ships. During this study we will do the following. (1) The design sea states that closely resemble the actual sea states which are considered as the most severe for hull structures are proposed. (2) The practical estimation methods of the design sea states are proposed by parametric studies using the results of series calculation of representative Merchant Ships. (3) The practical estimation methods of design regular waves resulting in the same level of stresses as that induced in irregular waves under the design sea states are proposed. (4) The practical estimation methods of the design loads such as Ship motions, accelerations, hull-girder bending moments, and hydrodynamic pressures that are induced under design regular waves are briefly introduced. The findings in this study have been summarized and implemented in the new design standards for tanker, bulk carrier, and container Ship structures ("Guidelines for Tanker Structures, "2001, Nippon Kaiji Kyokai; "Guidelines for Bulk Carrier Structures," 2002, Nippon Kaiji Kyokai; "Guidelines for Container Carrier Structures, " 2003, Nippon Kaiji Kyokai).

  • Design Loads Used for Direct Strength Assessment of Merchant Ship Structures
    23rd International Conference on Offshore Mechanics and Arctic Engineering Volume 3, 2004
    Co-Authors: Tingyao Zhu, Toshiyuki Shigemi
    Abstract:

    This paper summarizes the results of extensive research on the design loads used for strength assessment of Merchant Ship structures such as tankers, bulk carriers and container Ships. The main aim of the research was to develop practical estimation methods of design loads having rational technical backgrounds acting on primary structural members of tankers, bulk carriers and container Ships. During this study: 1) The design sea states that closely resemble the actual sea states which are considered as the most severe for hull structures are proposed. 2) The practical estimation methods of the design sea states are proposed by parametric studies using the results of series calculation of representative Merchant Ships. 3) The practical estimation methods of design regular waves resulting in the same level of stresses with that induced in irregular waves under the design sea states are proposed. 4) The practical estimation methods of the design loads such as Ship motions, accelerations, hull-girder bending moments and hydrodynamic pressures that are induced under design regular waves are briefly introduced. The findings in this study have been summarized and implemented in the new design standards for tanker, bulk carrier and container Ship structures. (Guidelines for Tanker Structures, 2001, Nippon Kaiji Kyokai. Guidelines for Bulk Carrier Structures, 2002, Nippon Kaiji Kyokai. Guidelines for container Carrier Structures, 2003, Nippon Kaiji Kyokai.)Copyright © 2004 by ASME

Richard M Heitmeyer - One of the best experts on this subject based on the ideXlab platform.

  • Merchant Ship radiated noise source levels
    Journal of the Acoustical Society of America, 2011
    Co-Authors: Stephen C Wales, Richard M Heitmeyer
    Abstract:

    Ship‐radiated noise is the principal source of noise in the 20–300 Hz frequency regime. This presentation provides a review of the issues relating to measuring Ship‐radiated noise source levels and predicting the source levels from Ship parameters. The process of measuring and calculating the source levels is covered, including a discussion of propagation effects and source representation. Based on measurement results it is shown that, contrary to the classical model of Shipping source levels, there is a negligible correlation between the source levels of an ensemble of Ships and the transiting speeds and lengths of those Ships. Issues concerning using the source level model in a modeling environment are discussed, including some effects of changing speed and source depth. Additionally, evidence is presented that predictions of increases in the source levels of the world’s Ships based on increases in their speeds is not justified, while increases due to size (length) are not trivial. [Work supported by the ONR through NRL‐base funding.]

  • an ensemble source spectra model for Merchant Ship radiated noise
    Journal of the Acoustical Society of America, 2002
    Co-Authors: Stephen C Wales, Richard M Heitmeyer
    Abstract:

    This paper presents an evaluation of the classical model for determining an ensemble of the broadband source spectra of the sound generated by individual Ships and proposes an alternate model to overcome the deficiencies in the classical model. The classical model, proposed by Ross [Mechanics of Underwater Noise (Pergamon, New York, 1976)] postulates that the source spectrum for an individual Ship is proportional to a baseline spectrum with the constant of proportionality determined by a power-law relationShip on the Ship speed and length. The model evaluation, conducted on an ensemble of 54 source spectra over a 30-1200-Hz to 1200-Hz frequency band, shows that this assumption yields large rms errors in the broadband source level for the individual Ships and significantly overestimates the variability in the source level across the ensemble of source spectra. These deficiencies are a consequence of the negligible correlation between the source level and the Ship speed and the source level and the Ship length. The alternate model proposed here represents the individual Ship spectra by a modified rational spectrum where the poles and zeros are restricted to the real axis and the exponents of the terms are not restricted to integer values. An evaluation of this model on the source spectra ensemble indicates that the rms errors are significantly less than those obtained with any model where the frequency dependence is represented by a single baseline spectrum. Furthermore, at high frequencies (400 to 1200 Hz), a single-term rational spectrum model is sufficient to describe the frequency dependence and, at the low frequencies (30 to 400 Hz), there is only a modest reduction in the rms error for a higher order model. Finally, a joint probability density on the two parameters of the single term model based on the measured histograms of these parameters is proposed. This probability density provides a mechanism for generating an ensemble of Ship spectra.

Tingyao Zhu - One of the best experts on this subject based on the ideXlab platform.

  • Design Loads Used for Direct Strength Assessment of Merchant Ship Structures
    Journal of Offshore Mechanics and Arctic Engineering, 2006
    Co-Authors: Tingyao Zhu, Toshiyuki Shigemi
    Abstract:

    This paper summarizes the results of extensive research on the design loads used for strength assessment of Merchant Ship structures such as tankers, bulk carriers, and container Ships. The main aim of the research was to develop practical estimation methods of design loads having rational technical backgrounds acting on primary structural members of tankers, bulk carriers, and container Ships. During this study we will do the following. (1) The design sea states that closely resemble the actual sea states which are considered as the most severe for hull structures are proposed. (2) The practical estimation methods of the design sea states are proposed by parametric studies using the results of series calculation of representative Merchant Ships. (3) The practical estimation methods of design regular waves resulting in the same level of stresses as that induced in irregular waves under the design sea states are proposed. (4) The practical estimation methods of the design loads such as Ship motions, accelerations, hull-girder bending moments, and hydrodynamic pressures that are induced under design regular waves are briefly introduced. The findings in this study have been summarized and implemented in the new design standards for tanker, bulk carrier, and container Ship structures ("Guidelines for Tanker Structures, "2001, Nippon Kaiji Kyokai; "Guidelines for Bulk Carrier Structures," 2002, Nippon Kaiji Kyokai; "Guidelines for Container Carrier Structures, " 2003, Nippon Kaiji Kyokai).

  • Design Loads Used for Direct Strength Assessment of Merchant Ship Structures
    23rd International Conference on Offshore Mechanics and Arctic Engineering Volume 3, 2004
    Co-Authors: Tingyao Zhu, Toshiyuki Shigemi
    Abstract:

    This paper summarizes the results of extensive research on the design loads used for strength assessment of Merchant Ship structures such as tankers, bulk carriers and container Ships. The main aim of the research was to develop practical estimation methods of design loads having rational technical backgrounds acting on primary structural members of tankers, bulk carriers and container Ships. During this study: 1) The design sea states that closely resemble the actual sea states which are considered as the most severe for hull structures are proposed. 2) The practical estimation methods of the design sea states are proposed by parametric studies using the results of series calculation of representative Merchant Ships. 3) The practical estimation methods of design regular waves resulting in the same level of stresses with that induced in irregular waves under the design sea states are proposed. 4) The practical estimation methods of the design loads such as Ship motions, accelerations, hull-girder bending moments and hydrodynamic pressures that are induced under design regular waves are briefly introduced. The findings in this study have been summarized and implemented in the new design standards for tanker, bulk carrier and container Ship structures. (Guidelines for Tanker Structures, 2001, Nippon Kaiji Kyokai. Guidelines for Bulk Carrier Structures, 2002, Nippon Kaiji Kyokai. Guidelines for container Carrier Structures, 2003, Nippon Kaiji Kyokai.)Copyright © 2004 by ASME

Stephen C Wales - One of the best experts on this subject based on the ideXlab platform.

  • Merchant Ship radiated noise source levels
    Journal of the Acoustical Society of America, 2011
    Co-Authors: Stephen C Wales, Richard M Heitmeyer
    Abstract:

    Ship‐radiated noise is the principal source of noise in the 20–300 Hz frequency regime. This presentation provides a review of the issues relating to measuring Ship‐radiated noise source levels and predicting the source levels from Ship parameters. The process of measuring and calculating the source levels is covered, including a discussion of propagation effects and source representation. Based on measurement results it is shown that, contrary to the classical model of Shipping source levels, there is a negligible correlation between the source levels of an ensemble of Ships and the transiting speeds and lengths of those Ships. Issues concerning using the source level model in a modeling environment are discussed, including some effects of changing speed and source depth. Additionally, evidence is presented that predictions of increases in the source levels of the world’s Ships based on increases in their speeds is not justified, while increases due to size (length) are not trivial. [Work supported by the ONR through NRL‐base funding.]

  • an ensemble source spectra model for Merchant Ship radiated noise
    Journal of the Acoustical Society of America, 2002
    Co-Authors: Stephen C Wales, Richard M Heitmeyer
    Abstract:

    This paper presents an evaluation of the classical model for determining an ensemble of the broadband source spectra of the sound generated by individual Ships and proposes an alternate model to overcome the deficiencies in the classical model. The classical model, proposed by Ross [Mechanics of Underwater Noise (Pergamon, New York, 1976)] postulates that the source spectrum for an individual Ship is proportional to a baseline spectrum with the constant of proportionality determined by a power-law relationShip on the Ship speed and length. The model evaluation, conducted on an ensemble of 54 source spectra over a 30-1200-Hz to 1200-Hz frequency band, shows that this assumption yields large rms errors in the broadband source level for the individual Ships and significantly overestimates the variability in the source level across the ensemble of source spectra. These deficiencies are a consequence of the negligible correlation between the source level and the Ship speed and the source level and the Ship length. The alternate model proposed here represents the individual Ship spectra by a modified rational spectrum where the poles and zeros are restricted to the real axis and the exponents of the terms are not restricted to integer values. An evaluation of this model on the source spectra ensemble indicates that the rms errors are significantly less than those obtained with any model where the frequency dependence is represented by a single baseline spectrum. Furthermore, at high frequencies (400 to 1200 Hz), a single-term rational spectrum model is sufficient to describe the frequency dependence and, at the low frequencies (30 to 400 Hz), there is only a modest reduction in the rms error for a higher order model. Finally, a joint probability density on the two parameters of the single term model based on the measured histograms of these parameters is proposed. This probability density provides a mechanism for generating an ensemble of Ship spectra.

Charles A. Lin - One of the best experts on this subject based on the ideXlab platform.

  • Monthly summaries of Merchant Ship surface marine observations and implications for climate variability studies
    Climate Dynamics, 1992
    Co-Authors: Réjean Michaud, Charles A. Lin
    Abstract:

    We compute the interannual fluctuations of the surface heat budget of the North Atlantic using the trimmed monthly summaries of the Comprehensive Ocean-Atmosphere DataSet (COADS) for the period 1950–1979. The presence of long-period trends in the heat budget imply large variations of the northward cross-equatorial heat transport over the years. To assess the reliability of these variations, we compare the COADS climate signal to that derived from the ocean weather stations (OWSs) of the North Atlantic. The sea surface temperature, air temperature and sea level pressure show good correlation between the anomaly time series derived from the Merchant Ship monthly summaries of COADS, and those derived from OWS monthly summaries, except for northernmost locations during winter. In contrast, the sensible and latent heat parameters, which require simultaneous measurements of various variables, have Merchant Ships and ocean weather stations anomaly time series that are poorly correlated. Only in heavily travelled latitudes and during winter, when the air-sea heat exchange anomalies are large, are the Merchant Ship measurements able to reproduce the interannual fluctuations of the heat fluxes. The long-period trends in the surface heat budget of North Atlantic equatorward of 40° N implied by COADS thus appear unrepresentative of true climate trends. The COADS trends result from a gradual increase in the magnitude of the reported winds over the years due probably to variations in the ratio of measured to estimated winds, as well as from long period fluctuations in the near surface vertical temperature and humidity gradients.