PORO-FSSI-FOAM model for seafloor liquefaction around a pipeline under combined random wave and current loading

2021 ◽  
Vol 107 ◽  
pp. 102497
Author(s):  
Zuodong Liang ◽  
Dong-Sheng Jeng
Keyword(s):  
Random Wave ◽  
Foam Model ◽  
Current Loading

EXPERIMENTAL STUDY ON RANDOM WAVE PRESSURE AFTER WAVE BREAKING ACTING ON SEAWALL ON LAND SIDE OF SHORELINE

2018 ◽  
Vol 74 (2) ◽  
pp. I_1063-I_1068
Author(s):  
Kenya TAKAHASHI ◽  
Yu SOUMA ◽  
Toshimasa ISHII ◽  
Takeshi NISHIHATA ◽  
Takeru MICHIMAE ◽  
...  
Keyword(s):  
Experimental Study ◽  
Wave Breaking ◽  
Random Wave ◽  
Wave Pressure

scholarly journals Time Scale for Scour Beneath Pipelines Due to Long-Crested and Short-Crested Nonlinear Random Waves Plus Current

2021 ◽  
Vol 9 (2) ◽  
pp. 114
Author(s):  
Dag Myrhaug ◽  
Muk Chen Ong
Keyword(s):  
Time Scale ◽  
Current Flow ◽  
Irregular Waves ◽  
Wave Crest ◽  
Random Wave ◽  
Random Waves ◽  
Flow Conditions ◽  
Regular Waves ◽  
Nonlinear Random Waves ◽  
2D And 3D

This article derives the time scale of pipeline scour caused by 2D (long-crested) and 3D (short-crested) nonlinear irregular waves and current for wave-dominant flow. The motivation is to provide a simple engineering tool suitable to use when assessing the time scale of equilibrium pipeline scour for these flow conditions. The method assumes the random wave process to be stationary and narrow banded adopting a distribution of the wave crest height representing 2D and 3D nonlinear irregular waves and a time scale formula for regular waves plus current. The presented results cover a range of random waves plus current flow conditions for which the method is valid. Results for typical field conditions are also presented. A possible application of the outcome of this study is that, e.g., consulting engineers can use it as part of assessing the on-bottom stability of seabed pipelines.

scholarly journals MEASUREMENTS AND INFORMATION IN SPIN FOAM MODELS

2012 ◽  
Vol 27 (28) ◽  
pp. 1250164
Author(s):  
J. MANUEL GARCÍA-ISLAS
Keyword(s):  
Information Theory ◽  
Quantum Gravity ◽  
Cosmological Constant ◽  
Shannon Entropy ◽  
Three Dimensional ◽  
Spin Network ◽  
Spin Foam Models ◽  
Foam Model ◽  
Spin Foam Model ◽  
Spin Foam

In the three-dimensional spin foam model of quantum gravity with a cosmological constant, there exists a set of observables associated with spin network graphs. A set of probabilities is calculated from these observables, and hence the associated Shannon entropy can be defined. We present the Shannon entropy associated with these observables and find some interesting bounded inequalities. The problem relates measurements, entropy and information theory in a simple way which we explain.

scholarly journals Experiment Investigation of Bistable Vibration Energy Harvesting with Random Wave Environment

2021 ◽  
Vol 11 (9) ◽  
pp. 3868
Author(s):  
Qiong Wu ◽  
Hairui Zhang ◽  
Jie Lian ◽  
Wei Zhao ◽  
Shijie Zhou ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Energy Harvesting ◽  
Cantilever Beam ◽  
Large Scale ◽  
Low Frequency ◽  
Vibration Energy ◽  
Random Wave ◽  
Periodic Signal ◽  
Vibration Energy Harvesting ◽  
Motion Activity

The energy harvested from the renewable energy has been attracting a great potential as a source of electricity for many years; however, several challenges still exist limiting output performance, such as the package and low frequency of the wave. Here, this paper proposed a bistable vibration system for harvesting low-frequency renewable energy, the bistable vibration model consisting of an inverted cantilever beam with a mass block at the tip in a random wave environment and also develop a vibration energy harvesting system with a piezoelectric element attached to the surface of a cantilever beam. The experiment was carried out by simulating the random wave environment using the experimental equipment. The experiment result showed a mass block’s response vibration was indeed changed from a single stable vibration to a bistable oscillation when a random wave signal and a periodic signal were co-excited. It was shown that stochastic resonance phenomena can be activated reliably using the proposed bistable motion system, and, correspondingly, large-scale bistable responses can be generated to realize effective amplitude enlargement after input signals are received. Furthermore, as an important design factor, the influence of periodic excitation signals on the large-scale bistable motion activity was carefully discussed, and a solid foundation was laid for further practical energy harvesting applications.

scholarly journals Lifetime and reliability improvements in modular multilevel converters using controlled circulating current

2021 ◽  
Author(s):  
Nasiru B. Kadandani ◽  
Mohamed Dahidah ◽  
Salaheddine Ethni ◽  
Musbahu Muhammad
Keyword(s):  
Control Method ◽  
Semiconductor Devices ◽  
Junction Temperature ◽  
Multilevel Converters ◽  
Control Approach ◽  
Circulating Current ◽  
Inherent Feature ◽  
Modular Multilevel Converters ◽  
Current Loading ◽  
Laboratory Prototype

AbstractCirculating current has been an inherent feature of modular multilevel converters (MMC), which results in second-order harmonics on the arms currents. If not properly controlled, the circulating current can affect the lifetime and reliability of a converter by increasing the current loading, loss distribution, and junction temperature of its semiconductor devices. This paper proposes controlled circulating current injection as a means of improving the lifetime and reliability of an MMC. The proposed method involves modifying the reference modulating signals of the converter arms to include the controlled differential voltage as an offset. The junction temperature of the semiconductor devices obtained from an electro-thermal simulation is processed to deduce the lifetime and reliability of the converter. The obtained results are benchmarked against a case where the control method is not incorporated. The incorporation of the proposed control method results in a 68.25% increase in the expected lifetime of the converter and a 3.06% increase on its reliability index. Experimental results of a scaled down laboratory prototype validate the effectiveness of the proposed control approach.

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