The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
John A Hildebrand - One of the best experts on this subject based on the ideXlab platform.
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Container Ship source level and directionality measurements
Journal of the Acoustical Society of America, 2019Co-Authors: Martin Gassmann, Sean M Wiggins, Lee B Kindberg, John A HildebrandAbstract:Underwater radiated noise from Container Ships was measured opportunistically from multiple spatial aspects to estimate directionality and signature source levels. Transiting Ships were tracked via the Automatic Identification System in a Shipping lane while acoustic pressure was measured at the Ships’ keel and beam aspects. Port and starboard beam aspects were 15, 30, and 45 deg in compliance with Ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd’s mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. In addition, recordings were made at a ∼10 deg starboard aspect and utilized to measure and compare signatures of MAERSK G-class Container Ships before and after the Ships were equipped with new propellers as part of MAERSK’s $100+ million Radical Retrofit Program.Underwater radiated noise from Container Ships was measured opportunistically from multiple spatial aspects to estimate directionality and signature source levels. Transiting Ships were tracked via the Automatic Identification System in a Shipping lane while acoustic pressure was measured at the Ships’ keel and beam aspects. Port and starboard beam aspects were 15, 30, and 45 deg in compliance with Ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd’s mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. In addition, recordings were made at a ∼10 deg starboard aspect and utilized to measure and compare signatures of MAERSK G-class Container Ship...
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deep water measurements of Container Ship radiated noise signatures and directionality
Journal of the Acoustical Society of America, 2017Co-Authors: Martin Gassmann, Sean M Wiggins, John A HildebrandAbstract:Underwater radiated noise from merchant Ships was measured opportunistically from multiple spatial aspects to estimate signature source levels and directionality. Transiting Ships were tracked via the Automatic Identification System in a Shipping lane while acoustic pressure was measured at the Ships' keel and beam aspects. Port and starboard beam aspects were 15°, 30°, and 45° in compliance with Ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Additional recordings were made at a 10° starboard aspect. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd's mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. Results were exemplified with a 4870 and a 10 036 twenty-foot equivalent unit Container Ship at 40%–56% and 87% of service speeds, respectively. For the larger Ship, opportunistic ANSI/I...
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relationShip between Container Ship underwater noise levels and Ship design operational and oceanographic conditions
Scientific Reports, 2013Co-Authors: Megan F Mckenna, Sean M Wiggins, John A HildebrandAbstract:RelationShip between Container Ship underwater noise levels and Ship design, operational and oceanographic conditions
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RelationShip between Container Ship underwater noise levels and Ship design, operational and oceanographic conditions
Scientific Reports, 2013Co-Authors: Megan F Mckenna, Sean M Wiggins, John A HildebrandAbstract:Low-frequency ocean ambient noise is dominated by noise from commercial Ships, yet understanding how individual Ships contribute deserves further investigation. This study develops and evaluates statistical models of Container Ship noise in relation to design characteristics, operational conditions and oceanographic settings. Five-hundred Ship passages and nineteen covariates were used to build generalized additive models. Opportunistic acoustic measurements of Ships transiting offshore California were collected using seafloor acoustic recorders. A 5–10 dB range in broadband source level was found for Ships depending on the transit conditions. For a Ship recorded multiple times traveling at different speeds, cumulative noise was lowest at 8 knots, 65% reduction in operational speed. Models with highest predictive power, in order of selection, included Ship speed, size and time of year. Uncertainty in source depth and propagation affected model fit. These results provide insight on the conditions that produce higher levels of underwater noise from Container Ships.
Megan F Mckenna - One of the best experts on this subject based on the ideXlab platform.
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relationShip between Container Ship underwater noise levels and Ship design operational and oceanographic conditions
Scientific Reports, 2013Co-Authors: Megan F Mckenna, Sean M Wiggins, John A HildebrandAbstract:RelationShip between Container Ship underwater noise levels and Ship design, operational and oceanographic conditions
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RelationShip between Container Ship underwater noise levels and Ship design, operational and oceanographic conditions
Scientific Reports, 2013Co-Authors: Megan F Mckenna, Sean M Wiggins, John A HildebrandAbstract:Low-frequency ocean ambient noise is dominated by noise from commercial Ships, yet understanding how individual Ships contribute deserves further investigation. This study develops and evaluates statistical models of Container Ship noise in relation to design characteristics, operational conditions and oceanographic settings. Five-hundred Ship passages and nineteen covariates were used to build generalized additive models. Opportunistic acoustic measurements of Ships transiting offshore California were collected using seafloor acoustic recorders. A 5–10 dB range in broadband source level was found for Ships depending on the transit conditions. For a Ship recorded multiple times traveling at different speeds, cumulative noise was lowest at 8 knots, 65% reduction in operational speed. Models with highest predictive power, in order of selection, included Ship speed, size and time of year. Uncertainty in source depth and propagation affected model fit. These results provide insight on the conditions that produce higher levels of underwater noise from Container Ships.
Sean M Wiggins - One of the best experts on this subject based on the ideXlab platform.
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Container Ship source level and directionality measurements
Journal of the Acoustical Society of America, 2019Co-Authors: Martin Gassmann, Sean M Wiggins, Lee B Kindberg, John A HildebrandAbstract:Underwater radiated noise from Container Ships was measured opportunistically from multiple spatial aspects to estimate directionality and signature source levels. Transiting Ships were tracked via the Automatic Identification System in a Shipping lane while acoustic pressure was measured at the Ships’ keel and beam aspects. Port and starboard beam aspects were 15, 30, and 45 deg in compliance with Ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd’s mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. In addition, recordings were made at a ∼10 deg starboard aspect and utilized to measure and compare signatures of MAERSK G-class Container Ships before and after the Ships were equipped with new propellers as part of MAERSK’s $100+ million Radical Retrofit Program.Underwater radiated noise from Container Ships was measured opportunistically from multiple spatial aspects to estimate directionality and signature source levels. Transiting Ships were tracked via the Automatic Identification System in a Shipping lane while acoustic pressure was measured at the Ships’ keel and beam aspects. Port and starboard beam aspects were 15, 30, and 45 deg in compliance with Ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd’s mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. In addition, recordings were made at a ∼10 deg starboard aspect and utilized to measure and compare signatures of MAERSK G-class Container Ship...
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deep water measurements of Container Ship radiated noise signatures and directionality
Journal of the Acoustical Society of America, 2017Co-Authors: Martin Gassmann, Sean M Wiggins, John A HildebrandAbstract:Underwater radiated noise from merchant Ships was measured opportunistically from multiple spatial aspects to estimate signature source levels and directionality. Transiting Ships were tracked via the Automatic Identification System in a Shipping lane while acoustic pressure was measured at the Ships' keel and beam aspects. Port and starboard beam aspects were 15°, 30°, and 45° in compliance with Ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Additional recordings were made at a 10° starboard aspect. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd's mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. Results were exemplified with a 4870 and a 10 036 twenty-foot equivalent unit Container Ship at 40%–56% and 87% of service speeds, respectively. For the larger Ship, opportunistic ANSI/I...
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relationShip between Container Ship underwater noise levels and Ship design operational and oceanographic conditions
Scientific Reports, 2013Co-Authors: Megan F Mckenna, Sean M Wiggins, John A HildebrandAbstract:RelationShip between Container Ship underwater noise levels and Ship design, operational and oceanographic conditions
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RelationShip between Container Ship underwater noise levels and Ship design, operational and oceanographic conditions
Scientific Reports, 2013Co-Authors: Megan F Mckenna, Sean M Wiggins, John A HildebrandAbstract:Low-frequency ocean ambient noise is dominated by noise from commercial Ships, yet understanding how individual Ships contribute deserves further investigation. This study develops and evaluates statistical models of Container Ship noise in relation to design characteristics, operational conditions and oceanographic settings. Five-hundred Ship passages and nineteen covariates were used to build generalized additive models. Opportunistic acoustic measurements of Ships transiting offshore California were collected using seafloor acoustic recorders. A 5–10 dB range in broadband source level was found for Ships depending on the transit conditions. For a Ship recorded multiple times traveling at different speeds, cumulative noise was lowest at 8 knots, 65% reduction in operational speed. Models with highest predictive power, in order of selection, included Ship speed, size and time of year. Uncertainty in source depth and propagation affected model fit. These results provide insight on the conditions that produce higher levels of underwater noise from Container Ships.
Dimitris Gritzalis - One of the best experts on this subject based on the ideXlab platform.
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Analyzing Congestion Interdependencies of Ports and Container Ship Routes in the Maritime Network Infrastructure
IEEE Access, 2018Co-Authors: George Stergiopoulos, Evangelos Valvis, Dimitris Mitrodimas, Dimitrios Lekkas, Dimitris GritzalisAbstract:Events, such as prolonged congestion in ports or unavailable Ship routes in the maritime network, often initiate cascading congestions that block transportation and/or disrupt services over wide areas. Existing traffic flow analysis methods lack the ability to understand the cascading effects of delays in Ship routes or how to reduce overall delays in greater maritime areas. Dependency risk graphs have been proposed as a tool for analyzing such cascading events using dependency chains. This paper proposes a risk-based interdependency analysis method capable to detect large-scale traffic congestions between interconnected ports and Ship routes in the maritime network and provide solutions to improve flow. Presented dependency risk chains of ports along with graph theory help us analyze Ship routes and detect ports that are affected most when other major ports are congested in the maritime network, detect the causes of bottlenecks, and provide valuable info in relieving delays across Container Ship routes. We apply the proposed method on historical Container Ship routing data provided by the MarineTraffic company that maintains a comprehensive maritime database worldwide for more than six million users monthly. This application-oriented, interdisciplinary effort culminated in a prototype tool is able to analyze the historical data for Container Ships in the entire global maritime network and detect congestion dependencies. The tool can be used to identify key Shipping routes or ports that: 1) are prone to delays; 2) greatly affect the overall maritime network due to position, connections and risk of congestion; and/or 3) get affected the most by delays in previous route legs.
Deyu Wang - One of the best experts on this subject based on the ideXlab platform.
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design similar scale model of a 10 000 teu Container Ship through combined ultimate longitudinal bending and torsion analysis
Applied Ocean Research, 2019Co-Authors: Chonglei Wang, Jiameng Wu, Deyu WangAbstract:Abstract This paper firstly figures out a similar scale model regarding ultimate strength experiment of a typical ultra large Container Ship (ULCS) through combined ultimate longitudinal bending and torsion analysis, in which the similarity theory is proposed to design the scale model for reflecting the progressive collapse behaviors of true Ships in ultimate strength model test. The present study presents the similarity between scale model and true Ship in cross-section considering the height of neutral axis, the section modulus, the inertia moment about neutral axis and the polar inertia moment should fit the geometrical similarity theory, and in strength considering buckling strength and shear ultimate strength of plates and stiffened panels should fit the strength similarity theory. Numerical investigations are conducted on the ultimate strength of a 10,000 TEU Container Ship and the similar scale model under pure hogging bending, pure torsion and combined bending and torsion, respectively. The nonlinear finite element method (NFEM) is adopted considering the effects of initial deformations and both material and geometric nonlinearities. Finally, the numerical results are compared with each other and discussed showing a good agreement in both elastic and inelastic range during the progressive collapse behaviors, which means the similar scale model can represent the true Ship regarding ultimate strength test. And the similarity theory is verified quite stable after the uncertainty analysis.
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numerical investigation of three dimensional hull girder ultimate strength envelope for an ultra large Container Ship
Ocean Engineering, 2018Co-Authors: Chonglei Wang, Jiameng Wu, Deyu WangAbstract:Abstract Ultra large Container Ship (ULCS) structures feature large deck openings and low torsional rigidity. It is essential to accurately evaluate the maximum loading carrying capacity of Ship structures. When the Ship sails at an oblique heading in rough sea, the horizontal and torsional moments may approach or even exceed the magnitude of vertical bending moment. In such cases, hull girder ultimate strength assessment of Container Ships under load combinations comprising of vertical bending moment, horizontal bending moment and torsion is necessary in their structural design stage. In this paper, special attentions are thus paid to the hull girder ultimate strength of an ULCS (i.e., a typical 10,000 TEU Container Ship) subjected to combined three load components mentioned above, which is also a common load case in Ships and Ship-shaped offshore structures and it is assumed that the three kinds of main loads can be combined each other freely. A series of nonlinear finite element analyses (NFEA) is carried out. Effects of fabrication related initial imperfections are investigated in the present study. Based on the computed numerical results, the 3D hull girder ultimate strength envelope considering initial deformation and incorporating the interaction relationShips among three kinds of load components mentioned above is established.
