Reliability Assessment for TLP Tether Overload in Nonlinear Waves

2011 ◽  
Author(s):  
O̸istein Hagen
Keyword(s):  
Rogue Waves ◽  
Parametric Models ◽  
Future Research ◽  
Detailed Knowledge ◽  
Cooperative Research ◽  
Limit States ◽  
Annual Probability ◽  
Non Linear ◽  
Simple Scaling ◽  
Linear Effects

Non-linear effects caused by extreme crest loading might be governing for important structural limit states. For TLP’s, non-linear effects caused by extreme crest might lead to tether overload and tether slack. Simple scaling of ULS results is not necessarily adequate if wave in deck events (or other NL phenomena) might occur with annual probability >10−4. In this case ALS analysis should be performed, and detailed knowledge of the physics and statistics of extreme crest events, and of the loading caused by these waves, is required. Ignoring the possibility for wave in deck events and establishing the characteristic tension from data where there are no wave in deck events, might lead to unrealistic low estimates for the extreme tether tension. The present study demonstrates effects of the CresT JIP (Cooperative Research on Extreme Seas and their impacT) findings regarding extreme and rogue waves through a simplified reliability analysis of a generic TLP defined by the project. In this paper, SRA for tether overload is discussed, with emphasize on the effect of tension Twid caused by wave in deck events. Data from TLP basin test undertaken as part of the CresT JIP are applied, and parametric models for tether tension from measured crests and measured tether tension data are established. The model for Twid is used in the SRA for analysis of tether overloads for design sea states and for long term analysis for different geographic locations. Special attention is given to assessment of the effect of higher order crest non-linearities beyond 2nd order. The crest models are based on results from other work packages of the Crest JIP. Recommendations for future research needs are given.

Reliability Assessment of TLP Air-Gap in Nonlinear Waves

2011 ◽  
Author(s):  
Elzbieta M. Bitner-Gregersen
Keyword(s):  
Sea Water ◽  
Vertical Displacement ◽  
Rogue Waves ◽  
Future Research ◽  
Diffraction Radiation ◽  
Cooperative Research ◽  
Structure Reliability ◽  
Sensitivity Studies ◽  
Water Level Variations ◽  
Wave Nonlinearity

The present study demonstrates effects of the CresT JIP (Cooperative Research on Extreme Seas and their impacT) findings regarding extreme and rogue waves through a simplified structure reliability analysis of a generic TLP structure defined by the project. The study demonstrates effects of wave nonlinearity beyond the second order, diffraction-radiation of incoming waves with the structure, spatial variations of crest statistics, a vertical displacement of the TLP system at the deck location as well as sea water level variations due to surge and tide. In order to account for these effects a stochastic model is suggested. Sensitivity studies are carried out to identify importance of analysed parameters and their stochastic behaviour to the failure probability. Uncertainties related to the analysis are identified and ranked given special attention to the effect of wave nonlinearities beyond the 2nd order. Recommendations for future research needs are suggested.

Ocean Wave Non-Linearity and Wind Input in Directional Seas: Energy Input During Wave-Group Focussing

2018 ◽  
Author(s):  
Thomas A. A. Adcock ◽  
Paul H. Taylor
Keyword(s):  
Energy Input ◽  
Wind Waves ◽  
Rogue Waves ◽  
Wave Group ◽  
Spectral Evolution ◽  
Wave Groups ◽  
Small Influence ◽  
Non Linear ◽  
Linear Effects ◽  
Wind Input

There has been speculation that energy input (wind) can play an important role in the formation of rogue waves in the open ocean. Here we examine the role energy input can play by adding energy to the modified non-linear Schrödinger equation. We consider NewWave type wave-groups with spectra which are realistic for wind waves. We examine the case where energy input is added to the group as the wave-group focuses. We consider whether this energy input can cause significant non-linear effects to the subsequent spatial and spectral evolution. For the parameters considered here we find this to have only a small influence.

Determinants of perceived internal service complexity

2017 ◽  
Vol 29 (1) ◽  
pp. 123-152 ◽  
Author(s):  
Corina Braun ◽  
Karsten Hadwich
Keyword(s):  
Service Quality ◽  
Limiting Factors ◽  
Equation Modeling ◽  
Future Research ◽  
Hybrid Strategy ◽  
Content Type ◽  
Internal Customers ◽  
Non Linear ◽  
Internal Service Quality ◽  
Linear Effects

Purpose This paper aims to explore the determinants of perceived internal service complexity in internal service encounters. In this context, the nature of internal service complexity is considered, to identify its promoting and limiting factors, as well as its non-linear effects on internal service quality. Design/methodology/approach To acquire information on factors influencing internal service complexity, a broad literature review was conducted. Furthermore, to validate and verify these results, structural equation modeling’ was used in the context of a quantitative study with 705 internal customers. Findings The results revealed four promoting and seven limiting complexity determinants at organizational, interdepartmental and internal supplier-related levels. Moreover, the findings showed that an optimal, moderate level of internal service complexity maximizes internal service quality. Research limitations/implications As the findings are restricted to this study, further research should be conducted with regard to different types of companies and internal customers. Furthermore, future research should take variability over time into account. Executing a longitudinal approach to internal service complexity might therefore be appropriate. Practical implications Managers should note that exclusively reducing internal service complexity is insufficient; rather, a hybrid strategy of lowering and controlling is indispensable for an optimization. Based on the identified complexity determinants, a three-step guidance to optimize internal service is proposed. Originality/value Despite examining the construct complexity, previous research has neither analyzed internal service complexity nor studied its determinants. This paper provides an empirical model that analyzes inhibiting and promoting factors of internal service complexity as well as its non-linear effects on internal service quality.

Non-Linear Dynamics of Cardiovascular Variability Signals

1994 ◽  
Vol 33 (01) ◽  
pp. 81-84 ◽  
Author(s):  
S. Cerutti ◽  
S. Guzzetti ◽  
R. Parola ◽  
M.G. Signorini
Keyword(s):  
Dimensional Space ◽  
Severe Heart Failure ◽  
Parametric Models ◽  
Deterministic Systems ◽  
Finite Dimensional ◽  
Return Maps ◽  
Pathological Conditions ◽  
Non Linear ◽  
Space State

Abstract:Long-term regulation of beat-to-beat variability involves several different kinds of controls. A linear approach performed by parametric models enhances the short-term regulation of the autonomic nervous system. Some non-linear long-term regulation can be assessed by the chaotic deterministic approach applied to the beat-to-beat variability of the discrete RR-interval series, extracted from the ECG. For chaotic deterministic systems, trajectories of the state vector describe a strange attractor characterized by a fractal of dimension D. Signals are supposed to be generated by a deterministic and finite dimensional but non-linear dynamic system with trajectories in a multi-dimensional space-state. We estimated the fractal dimension through the Grassberger and Procaccia algorithm and Self-Similarity approaches of the 24-h heart-rate variability (HRV) signal in different physiological and pathological conditions such as severe heart failure, or after heart transplantation. State-space representations through Return Maps are also obtained. Differences between physiological and pathological cases have been assessed and generally a decrease in the system complexity is correlated to pathological conditions.

scholarly journals Sensitivity of wavepackets in jets to non-linear effects: the role of the critical layer

2015 ◽  
Author(s):  
Gilles Tissot ◽  
Mengqi Zhang ◽  
Francisco C. Lajús ◽  
André V. Cavalieri ◽  
Peter Jordan ◽  
...  
Keyword(s):  
Critical Layer ◽  
Non Linear ◽  
Linear Effects

scholarly journals Determinants of Non-Linear Effects of Fiscal Policy on Output: The Case of Bulgaria

2009 ◽  
Vol 4 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Vladimir Vladimirov ◽  
Maria Neycheva
Keyword(s):  
Fiscal Policy ◽  
Currency Board ◽  
Main Determinant ◽  
The Real ◽  
Real Gdp ◽  
Non Linear ◽  
Short Run ◽  
Linear Effects ◽  
Policy Impacts ◽  
The Government

Determinants of Non-Linear Effects of Fiscal Policy on Output: The Case of BulgariaThe paper illuminates the non-linear effects of the government budget on short-run economic activity. The study shows that in the Bulgarian economy under a Currency Board Arrangement the tax policy impacts the real growth in the standard Keynesian manner. On the other hand, the expenditure policy exhibits non-Keynesian behavior on the short-run output: cuts in government spending accelerate the real GDP growth. The main determinant of this outcome is the size of the discretionary budgetary changes. The results imply that the balanced budget rule improves the sustainability of public finances without assuring a growth-enhancing effect.

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