Comprehensive Diagnosis of Rotor Faults of Submersible Motors on Offshore Platforms

Author(s):  
Yahui Zhang ◽  
Kai Yang ◽  
Fan Yang ◽  
Zixin Li
1994 ◽  
Vol 16 (2) ◽  
pp. 43-48
Author(s):  
Do Son

This paper describes the results of measurements and analysis of the parameters, characterizing technical state of offshore platforms in Vietnam Sea. Based on decreasing in time material characteristics because of corrosion and local destruction assessment on residual life time of platforms is given and variants for its repair are recommended. The results allowed to confirm advantage of proposed technical diagnostic method in comparison with others and have been used for oil and gas platform of Joint Venture "Vietsovpetro" in South Vietnam.


2017 ◽  
Vol 10 (6) ◽  
pp. 461
Author(s):  
Mohammed-El-Amine Khodja ◽  
Ahmed Hamida Boudinar ◽  
Azeddine Bendiabdellah

2013 ◽  
Author(s):  
Roberto Piva ◽  
Margherita Latronico ◽  
Andrea Nero ◽  
Stefano Sartirana

Author(s):  
Mikkel Gerken

Chapter 10 addresses the salient alternative effects on knowledge ascriptions by developing the epistemic focal bias account. According to this account, denials of knowledge in the face of a salient alternative often amount to false negatives. But while this is argued to be central to a comprehensive diagnosis, it is recognized that other psychological factors may also influence this class of judgments, and some of these are discussed. Furthermore, the epistemic focal bias account is integrated with a number of assumptions drawn from cognitive pragmatics. In this manner, Chapter 10 provides an empirical account and philosophical diagnosis of the puzzling pattern of knowledge ascriptions constituted by salient alternative effects.


2021 ◽  
Vol 9 (3) ◽  
pp. 348
Author(s):  
Xue Long ◽  
Lu Liu ◽  
Shewen Liu ◽  
Shunying Ji

In cold regions, ice pressure poses a serious threat to the safe operation of ship hulls and fixed offshore platforms. In this study, a discrete element method (DEM) with bonded particles was adapted to simulate the generation and distribution of local ice pressures during the interaction between level ice and vertical structures. The strength and failure mode of simulated sea ice under uniaxial compression were consistent with the experimental results, which verifies the accuracy of the discrete element parameters. The crushing process of sea ice acting on the vertical structure simulated by the DEM was compared with the field test. The distribution of ice pressure on the contact surface was calculated, and it was found that the local ice pressure was much greater than the global ice pressure. The high-pressure zones in sea ice are mainly caused by its simultaneous destruction, and these zones are primarily distributed near the midline of the contact area of sea ice and the structure. The contact area and loading rate are the two main factors affecting the high-pressure zones. The maximum local and global ice pressures decrease with an increase in the contact area. The influence of the loading rate on the local ice pressure is caused by the change in the sea ice failure mode. When the loading rate is low, ductile failure of sea ice occurs, and the ice pressure increases with the increase in the loading rate. When the loading rate is high, brittle failure of sea ice occurs, and the ice pressure decreases with an increase in the loading rate. This DEM study of sea ice can reasonably predict the distribution of high-pressure zones on marine structures and provide a reference for the anti-ice performance design of marine structures.


2021 ◽  
Vol 11 (3) ◽  
pp. 908
Author(s):  
Jie Zeng ◽  
Panagiotis G. Asteris ◽  
Anna P. Mamou ◽  
Ahmed Salih Mohammed ◽  
Emmanuil A. Golias ◽  
...  

Buried pipes are extensively used for oil transportation from offshore platforms. Under unfavorable loading combinations, the pipe’s uplift resistance may be exceeded, which may result in excessive deformations and significant disruptions. This paper presents findings from a series of small-scale tests performed on pipes buried in geogrid-reinforced sands, with the measured peak uplift resistance being used to calibrate advanced numerical models employing neural networks. Multilayer perceptron (MLP) and Radial Basis Function (RBF) primary structure types have been used to train two neural network models, which were then further developed using bagging and boosting ensemble techniques. Correlation coefficients in excess of 0.954 between the measured and predicted peak uplift resistance have been achieved. The results show that the design of pipelines can be significantly improved using the proposed novel, reliable and robust soft computing models.


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