The Experts below are selected from a list of 5667 Experts worldwide ranked by ideXlab platform
Michael S Triantafyllou - One of the best experts on this subject based on the ideXlab platform.
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effect of higher stress harmonics and spectral width on fatigue damage of marine risers
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: Rachel Price, Haining Zheng, Yahya Modarressadeghi, Michael S TriantafyllouAbstract:Recently, experimental data from vortex induced vibrations (VIV) of long flexible cylinders have revealed the existence of (i) higher harmonic stress components, and (ii) chaotic response characteristics, in addition to the well-known first harmonic responses. To assess the effect of these phenomena on fatigue damage of long flexible structures, we Generate Alternative stress time series, with and then without higher harmonic components; as well as time series, which have either sharply peaked power spectral densities (PSD), or broad-banded PSDs, characteristic of chaotic response. We show that for stresses containing higher harmonics, the predicted fatigue damage to the riser can increase by a factor of 2.5 relative to the damage caused by stresses containing only the first harmonic and having equivalent total power. Likewise, for stresses with a significantly spread PSD, an indicator of chaotic response, the damage to the riser is increased by a factor of 1.8, relative to a stress with narrow-band PSD and the same total power. Thus, it is found that the increase in fatigue damage caused by chaotic response can be as significant as that caused by the stress higher harmonic components.Copyright © 2011 by ASME
Rachel Price - One of the best experts on this subject based on the ideXlab platform.
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effect of higher stress harmonics and spectral width on fatigue damage of marine risers
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: Rachel Price, Haining Zheng, Yahya Modarressadeghi, Michael S TriantafyllouAbstract:Recently, experimental data from vortex induced vibrations (VIV) of long flexible cylinders have revealed the existence of (i) higher harmonic stress components, and (ii) chaotic response characteristics, in addition to the well-known first harmonic responses. To assess the effect of these phenomena on fatigue damage of long flexible structures, we Generate Alternative stress time series, with and then without higher harmonic components; as well as time series, which have either sharply peaked power spectral densities (PSD), or broad-banded PSDs, characteristic of chaotic response. We show that for stresses containing higher harmonics, the predicted fatigue damage to the riser can increase by a factor of 2.5 relative to the damage caused by stresses containing only the first harmonic and having equivalent total power. Likewise, for stresses with a significantly spread PSD, an indicator of chaotic response, the damage to the riser is increased by a factor of 1.8, relative to a stress with narrow-band PSD and the same total power. Thus, it is found that the increase in fatigue damage caused by chaotic response can be as significant as that caused by the stress higher harmonic components.Copyright © 2011 by ASME
S X Fang - One of the best experts on this subject based on the ideXlab platform.
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assessing basin irrigation and scheduling strategies for saving irrigation water and controlling salinity in the upper yellow river basin china
Agricultural Water Management, 2007Co-Authors: Luis S. Pereira, J. M. Gonçalves, B Dong, S X FangAbstract:Water saving in irrigation is a key concern in the Yellow River basin. Excessive water diversions for irrigation waste water and produce waterlogging problems during the crop season and soil salinization in low lands. Supply control and inadequate functionality of the drainage system were identified as main factors for poor water management at farm level. Their improvement condition the adoption of water saving and salinity control practices. Focusing on the farm scale, studies to assess the potential for water savings included: (a) field evaluation of current basin irrigation practices and further use of the simulation models SRFR and SIRMOD to Generate Alternative improvements for the surface irrigation systems and (b) the use of the ISAREG model to simulate the present and improved irrigation scheduling Alternatives taking into consideration salinity control. Models were used interactively to define Alternatives for the irrigation systems and scheduling that would minimize percolation and produce water savings. Foreseen improvements refer to basin inflow discharges, land leveling and irrigation scheduling that could result in water savings of 33% relative to actual demand. These improvements would also reduce percolation and maintain water table depths below 1 m thereby reducing soil salinization.
Haining Zheng - One of the best experts on this subject based on the ideXlab platform.
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effect of higher stress harmonics and spectral width on fatigue damage of marine risers
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: Rachel Price, Haining Zheng, Yahya Modarressadeghi, Michael S TriantafyllouAbstract:Recently, experimental data from vortex induced vibrations (VIV) of long flexible cylinders have revealed the existence of (i) higher harmonic stress components, and (ii) chaotic response characteristics, in addition to the well-known first harmonic responses. To assess the effect of these phenomena on fatigue damage of long flexible structures, we Generate Alternative stress time series, with and then without higher harmonic components; as well as time series, which have either sharply peaked power spectral densities (PSD), or broad-banded PSDs, characteristic of chaotic response. We show that for stresses containing higher harmonics, the predicted fatigue damage to the riser can increase by a factor of 2.5 relative to the damage caused by stresses containing only the first harmonic and having equivalent total power. Likewise, for stresses with a significantly spread PSD, an indicator of chaotic response, the damage to the riser is increased by a factor of 1.8, relative to a stress with narrow-band PSD and the same total power. Thus, it is found that the increase in fatigue damage caused by chaotic response can be as significant as that caused by the stress higher harmonic components.Copyright © 2011 by ASME
Yahya Modarressadeghi - One of the best experts on this subject based on the ideXlab platform.
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effect of higher stress harmonics and spectral width on fatigue damage of marine risers
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: Rachel Price, Haining Zheng, Yahya Modarressadeghi, Michael S TriantafyllouAbstract:Recently, experimental data from vortex induced vibrations (VIV) of long flexible cylinders have revealed the existence of (i) higher harmonic stress components, and (ii) chaotic response characteristics, in addition to the well-known first harmonic responses. To assess the effect of these phenomena on fatigue damage of long flexible structures, we Generate Alternative stress time series, with and then without higher harmonic components; as well as time series, which have either sharply peaked power spectral densities (PSD), or broad-banded PSDs, characteristic of chaotic response. We show that for stresses containing higher harmonics, the predicted fatigue damage to the riser can increase by a factor of 2.5 relative to the damage caused by stresses containing only the first harmonic and having equivalent total power. Likewise, for stresses with a significantly spread PSD, an indicator of chaotic response, the damage to the riser is increased by a factor of 1.8, relative to a stress with narrow-band PSD and the same total power. Thus, it is found that the increase in fatigue damage caused by chaotic response can be as significant as that caused by the stress higher harmonic components.Copyright © 2011 by ASME