An Interrogation Scheme for Cost-Effective Structural Integrity Monitoring Using FBGs and DWDM Tunable Lasers

2006 ◽  
Author(s):  
Raimundo García-Olcina ◽  
Salvador Sales
Keyword(s):  
Structural Integrity ◽  
Cost Effective ◽  
Tunable Lasers ◽  
Integrity Monitoring

scholarly journals Bayesian maintenance decision optimisation based on computing the information value from condition inspections

2021 ◽  
pp. 1748006X2097812
Author(s):  
Guang Zou ◽  
Kian Banisoleiman ◽  
Arturo González
Keyword(s):  
Decision Making ◽  
Structural Integrity ◽  
Fatigue Cracking ◽  
Cost Effective ◽  
Offshore Structures ◽  
Information Value ◽  
Bayesian Decision ◽  
Maintenance Strategies ◽  
Optimal Maintenance ◽  
Maintenance Decision

A challenge in marine and offshore engineering is structural integrity management (SIM) of assets such as ships, offshore structures, mooring systems, etc. Due to harsh marine environments, fatigue cracking and corrosion present persistent threats to structural integrity. SIM for such assets is complicated because of a very large number of rewelded plates and joints, for which condition inspections and maintenance are difficult and expensive tasks. Marine SIM needs to take into account uncertainty in material properties, loading characteristics, fatigue models, detection capacities of inspection methods, etc. Optimising inspection and maintenance strategies under uncertainty is therefore vital for effective SIM and cost reductions. This paper proposes a value of information (VoI) computation and Bayesian decision optimisation (BDO) approach to optimal maintenance planning of typical fatigue-prone structural systems under uncertainty. It is shown that the approach can yield optimal maintenance strategies reliably in various maintenance decision making problems or contexts, which are characterized by different cost ratios. It is also shown that there are decision making contexts where inspection information doesn’t add value, and condition based maintenance (CBM) is not cost-effective. The CBM strategy is optimal only in the decision making contexts where VoI > 0. The proposed approach overcomes the limitation of CBM strategy and highlights the importance of VoI computation (to confirm VoI > 0) before adopting inspections and CBM.

Experimental Study on Inactivation of Heterosigma akashiwo by Pulsed Electric Field and Engine Waste Heat Treatment

2013 ◽  
Vol 864-867 ◽  
pp. 1822-1825
Author(s):  
Jun Feng Zhou ◽  
Le Ping Xu ◽  
Zhong Cheng Wang ◽  
Ting Fei Xie ◽  
Kai Liang Yang
Keyword(s):  
Ballast Water ◽  
Pulse Width ◽  
Structural Integrity ◽  
Waste Heat ◽  
Cost Effective ◽  
Heterosigma Akashiwo ◽  
Aquatic Species ◽  
Electrode Gap ◽  
Preheating Temperature ◽  
Inactivation Effect

Ballast water (BW) is essential in maintaining the balance and structural integrity of ships during voyage. However, invasive aquatic species discharged through ballast water is one of the most serious problems posed nowadays in the marine environment. Experimental inactivation effect on Heterosigma akashiwo by combined PEF and engine waste heat pretreatment was studied. Effect factors such as pulsed voltage, electrode gap, pulse width and preheating temperature were explored, and its mechanism of inactivate the Heterosigma akashiwo was analyzed. It was prospected to be effective to inactive the mircoalgae of ships ballast water by combined PEF and engine waste heat so as to obtain a cost-effective BW treatment with minimized environmental impacts.

Offloading Operability of Small Scale AG FLNG With Side-by-Side Moored Small Scale LNG Carrier in Offshore West Africa

2017 ◽  
Author(s):  
Mun-sung Kim ◽  
Eric Morilhat ◽  
X. C. Nguyen ◽  
Bo-hee Kim ◽  
Jung-moon Jang ◽  
...  
Keyword(s):  
West Africa ◽  
Relative Motion ◽  
Structural Integrity ◽  
Effective Means ◽  
Production Capacity ◽  
Cost Effective ◽  
Body Motion ◽  
Small Scale ◽  
Associated Gas ◽  
High Level

This study describes one of the technical solutions for Small Scale FLNG (SSFLNG)[1] development specifically designed to monetize Associated Gas (AG) of producing oil fields located within convenient distance of an existing LNG Plant or Port with LNG storage facility. Limited production capacity combined with short range small scale LNG carriers (SSLNGC), provide a cost effective means for LNG production. Ship to ship off-loading operation by loading arm has been considered in AG SSFLNG. Produced LNG is to be off-loaded from the SSFLNG to side-by-side moored SSLNGC. Relative motion and dynamic load acting on loading arm system in side-by-side mooring arrangement is one of key factors to estimate the offloading operability of the AG SSFLNG. In this paper, a numerical two-body motion analysis for the side-by-side moored SSFLNG in frequency- and time-domain is carried out. Also, the basic engineering work is carried out for the marine loading arms (MLA). Since the MLA reacts approximately as a linear system, it is calculated by a full spectral RAO analysis for each of the worst load cases issued from the spectral ranking. All loads and stresses inside the MLA are verified in accordance with EN1474-1[2] for the situations identified in the previous step. A high level fatigue analysis focused on the cryogenic swivel joints is carried out. Based on the numerical calculation for relative motion in side-by-side moored FLNG, we have been performed structural assessment for MLA in several environment conditions. The structural integrity of both MLA and the LNGC manifold are validated during offloading for Offshore West Africa.

Ultrasound and Nonlinear Resonant Testing of Nuclear Reactor Internals Bolts

2011 ◽  
Author(s):  
S. W. Glass ◽  
B. Thigpen ◽  
J. Renshaw
Keyword(s):  
Phased Array ◽  
Nuclear Reactor ◽  
Structural Integrity ◽  
Cost Effective ◽  
Life Extension ◽  
Safe Operation ◽  
Plant Life ◽  
Nuclear Plants ◽  
Bolt Failure ◽  
Reactor Internals

As many nuclear plants approach the end of their initial 40 year license period, inspection or replacement of their reactor internals bolts must be considered. This is consistent with the Materials Reliability Program (MRP 227/228) guideline for plant life extension [1,2]. Assurance of the internals structural integrity is essential for continued safe operation of these plants. If there is no suspicion or indication of bolt failure, simple inspection is normally more cost-effective than replacement. Inspection vendors have inspected thousands of internals bolts with conventional and Phased Array UT but different head configurations and bolt capture mechanisms mandate specific qualifications for each bolt type. In some cases, complex bolt and head geometries coupled with counter-bore and locking bar interferences render classical UT inspections difficult or impossible. A range of solutions to inspect reactor internals including these difficult-to-inspect-by-conventional-UT baffle bolts has been developed by several vendors [3]. This presentation references developments to make bolt inspection a relatively quick and easy task through adaptations to the SUSI submarine inspection platform, the extensive UT qualification work suitable for conventional UT plus more recent advanced nonlinear resonant techniques to distinguish between flawed or loose, vs. acceptable bolts where conventional UT cannot be applied. Initial evaluations show that these advanced techniques may have the ability to reliably detect smaller flaws than previously possible with conventional techniques as well as provide information on bolt tightness.

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