Effect of Polyester Mooring Stiffness on SCR Design for FPSO Application

2012 ◽  
Author(s):  
Gwo-Ang Chang ◽  
Pao-Lin Tan ◽  
Ken Huang ◽  
Tom Kwan
Keyword(s):  
Global Analysis ◽  
Dynamic Stiffness ◽  
Cost Effective ◽  
Systematic Investigation ◽  
Steel Catenary Riser ◽  
Motion Responses ◽  
Stiffness Model ◽  
Riser Design ◽  
The Impact ◽  
Selection Of

Polyester rope is a visco-elastic material and its stiffness is affected by mean tension, tension amplitude, loading period, and loading history. Qualitatively it may be felt that rope stiffness significantly affects vessel offset, which in turn affects riser performance and cost. However, a systematic investigation of the impact of rope stiffness on riser stress and fatigue life has not been published for a wide variety of design conditions. This paper describes such a study, and provides specific guidance to designers for the prudent selection of a rope stiffness model and values to achieve safe and cost effective riser design. This study investigated the effect of polyester rope stiffness on steel catenary riser (SCR) design for an FPSO sited in a variety of water depths considering environmental conditions representative of West Africa. Static/dynamic stiffness models for polyester rope in the recently issued ABS Guidance Notes on the Application of Fiber Rope for Offshore Mooring [1] were used in a global analysis to provide motion responses for the riser analysis. Time domain riser analysis was performed to obtain maximum riser stress and fatigue damage under various conditions. Based on the results of the investigation of riser and mooring analysis, guidance on the impact of rope stiffness to the riser design has been developed.

Effect of Polyester Mooring Stiffness on SCR Design for Semi Applications

2012 ◽  
Author(s):  
Peimin Cao ◽  
Hugh Thompson ◽  
Tom Kwan
Keyword(s):  
Dynamic Stiffness ◽  
Cost Effective ◽  
Fatigue Analysis ◽  
Offshore Drilling ◽  
Stiffness Model ◽  
Parametric Studies ◽  
Effective Choice ◽  
Riser Design ◽  
The Impact ◽  
Global Motion Analysis

Polyester rope mooring system has been widely accepted as a reliable and cost effective choice for deepwater mobile offshore drilling and floating production units in recent years. Polyester rope is made of a visco-elastic material and its stiffness is affected by mean tension, tension amplitude, loading period, and loading history. This creates complexity and uncertainty in the design of hull, mooring and riser systems. This paper summarizes the results of a JIP study investigating the effect of polyester rope stiffness on the SCR design of a semi-submersible FPU at two water depths in the Gulf of Mexico (GoM). A two-slope static-dynamic stiffness model proposed in the recently issued ABS “Guidance Notes on The Application of Fiber Rope for Offshore Mooring”[1] is used in the global motion analysis to provide input for the riser analysis. Parametric studies of SCR extreme analysis, wave fatigue analysis, and VIM fatigue analysis have been performed. Based on the results, recommendations on the impact of rope stiffness to the riser design are presented.

Quantitative Selection of Variation Reduction Plans

1998 ◽  
Author(s):  
Anna C. Thornton
Keyword(s):  
Risk Mitigation ◽  
Cost Effective ◽  
Variation Reduction ◽  
Multiple Quality Characteristics ◽  
Cost Effective Approach ◽  
Manufacturing Performance ◽  
The Impact ◽  
Manufacturing Variation ◽  
Selection Of

Abstract Quality has been a rallying call in the design and manufacturing world for the last two decades. One way to improve quality is to reduce the impact of manufacturing variation. Variation risk mitigation is challenging especially when a product has multiple quality characteristics and complex production and assembly. It is common wisdom that companies should identify and mitigate the risk associated with variation throughout the design process. As yield problems are identified, they should be mitigated using the most cost effective approach. One approach to variation risk mitigation is variation reduction (VR). VR targets reduction of variation introduced by existing manufacturing processes using tools such as Design of Experiments (DOE) and robust design. Many companies have specialized groups that specialize in these methods. VR teams have the role of improving manufacturing performance; however, these teams are limited in their resources. In addition, no tools exist to quantitatively determine where a VR team’s efforts are most effectively deployed. This paper provides a mathematical and optimization model to best allocate VR resources in a complex product.

scholarly journals Improvement of the Impact Properties of Composite Laminates by Means of Nano-Modification of the Matrix—A Review

2018 ◽  
Vol 8 (12) ◽  
pp. 2406 ◽  
Author(s):  
Hamed Saghafi ◽  
Mohamad Fotouhi ◽  
Giangiacomo Minak
Keyword(s):  
Composite Laminates ◽  
Cost Effective ◽  
Careful Consideration ◽  
Impact Performance ◽  
Compression After Impact ◽  
The Matrix ◽  
The Right ◽  
2D And 3D ◽  
The Impact ◽  
Selection Of

This paper reviews recent works on the application of nanofibers and nanoparticle reinforcements to enhance the interlaminar fracture toughness, to reduce the impact induced damage and to improve the compression after impact performance of fiber reinforced composites with brittle thermosetting resins. The nanofibers have been mainly used as mats embedded between plies of laminated composites, whereas the nanoparticles have been used in 0D, 1D, 2D, and 3D dimensional patterns to reinforce the matrix and consequently the composite. The reinforcement mechanisms are presented, and a comparison is done between the different papers in the literature. This review shows that in order to have an efficient reinforcement effect, careful consideration is required in the manufacturing, materials selection and reinforcement content and percentage. The selection of the right parameters can provide a tough and impact resistant composite with cost effective reinforcements.

EFFECTIVE DYNAMIC STIFFNESS MODEL AND ITS EFFECTS ON ROBOT SAFETY AND PERFORMANCE

2013 ◽  
Vol 37 (3) ◽  
pp. 395-403
Author(s):  
Dongjun Shin ◽  
Zhan Fan Quek
Keyword(s):  
Dynamic Stiffness ◽  
Joint Stiffness ◽  
Optimization Strategy ◽  
Design Guideline ◽  
Controller Gain ◽  
Stiffness Model ◽  
Effective Dynamic ◽  
Stiffness Characteristics ◽  
And Performance ◽  
The Impact

Due to the limited control bandwidth of pneumatic artificial muscles, joint stiffness characteristics and their effects on safety and performance of human-friendly robots should be considered in the frequency domain. This paper introduces the concept of effective dynamic stiffness and validates its model with the Stanford Safety Robot. Experimental results show that the dynamic stiffness demonstrates limited effects on the impact acceleration given the same impact velocity and controller gain, whereas it significantly affects control performance of position tracking due to pressure-induced non-linearities. A stiffness optimization strategy for safety and performance is discussed as a design guideline of human-friendly robots.

A New User Defined Element for Nonlinear Riser-Soil Interaction Analysis of Steel Catenary Riser Systems

2016 ◽  
Author(s):  
Jiayue Liu ◽  
Mehrdad Kimiaei ◽  
Mark Randolph
Keyword(s):  
Interaction Analysis ◽  
Global Analysis ◽  
Cost Effective ◽  
Steel Catenary Riser ◽  
Analysis And Design ◽  
Static And Dynamic Analysis ◽  
Finite Element Software ◽  
Nonlinear Springs ◽  
Fatigue Design ◽  
Software Packages

Steel Catenary Risers (SCRs) provide a technically feasible and commercially efficient solution for the offshore field developments in deep waters. Fatigue design of SCRs in the touchdown zone (TDZ) is among the most complicated engineering challenges in riser design. The cyclic interaction of the riser with seabed leads to a number of complex nonlinear behaviors including soil suction, separation of the riser from the soil, trench formation and degradation of soil resistance during cyclic loading. Accurate simulation of the riser-soil interaction has significant effects on the fatigue performance in the TDZ. Few hysteretic nonlinear riser-soil interaction models have recently been introduced and some of them have been implemented in commercial software packages for analysis and design of riser systems. Due to complexity of the models and also limited access to special software packages with in-built nonlinear soil models, traditional simple linear soil models are still being used widely for riser analysis, in particular for fatigue design. In this paper, one of the existing nonlinear hysteretic seabed model, already been used in a commercial analysis program OrcaFlex [1], has been implemented into general finite element software Abaqus [2], through the coding of a user defined element (UEL) subroutine. The paper documents the implementation of UEL into Abaqus and the establishment of global riser model for both static and dynamic analysis on which the pipe is modelled efficiently as series of unidirectional beam elements from floater to seabed, resting on a bed of nonlinear springs. Longitudinal friction between pipe and seabed has also been considered. A series of simulations are performed to illustrate the capabilities of the model. All these results have good agreement with those from OrcaFlex. Results indicate that the proposed UEL is capable of modelling nonlinear riser-soil interaction phenomena and has been verified to be a cost-effective alternative to OrcaFlex in terms of global analysis of SCRs. In addition, as an open source code, UEL provides the required tool for future development on nonlinear soil models. A new type of nonlinear soil with bilinear soil shear strength is modeled and its effect on structural performances of SCRs is investigated.

scholarly journals Selecting Bolt-on Dimensions for the EQ-5D: Testing the Impact of Hearing, Sleep, Cognition, Energy, and Relationships on Preferences Using Pairwise Choices

2020 ◽  
Vol 41 (1) ◽  
pp. 89-99
Author(s):  
Aureliano Paolo Finch ◽  
John Brazier ◽  
Clara Mukuria
Keyword(s):  
Online Survey ◽  
Logistic Models ◽  
Cost Effective ◽  
Health State ◽  
Health States ◽  
Cost Effective Approach ◽  
Level 3 ◽  
Severity Levels ◽  
The Impact ◽  
Selection Of

Background Generic preference-based measures (GPBMs) such as the EQ-5D are valid across many conditions, but in some cases, “bolting on” additional dimensions may improve validity. The selection of “bolt-ons” has been based on the psychometric impact of individual dimensions, but preferences provide another important way to select them. This study aims to test the potential of using pairwise choices to inform the selection of bolt-ons for the EQ-5D-5L. Methods General population preferences were collected using an online survey of 1040 UK residents. Three EQ-5D-5L health state pairs were selected based on pairs that had a 50:50 split in respondent preferences from a previous pairwise survey. Participants were presented with pairwise choices of EQ-5D-5L health states without and with bolt-ons of hearing, sleep, cognition, energy, and relationships, each added individually. Logistic models were used to assess the impact of bolt-ons, as well as bolt-ons at different severity levels, on the log odds of responders choosing between health states. Results Preferences varied according to the bolt-ons and their severity level (only levels 1, 3, and 5 were used). Additions of bolt-ons at level 1 generally resulted in nonstatistically significant differences while additions of bolt-ons at level 3 and level 5 produced a negative and statistically significant impact on preferences for the health state with the bolt-on. At level 5, hearing had the largest impact, followed by cognition, relationships, energy, and sleep. At level 3, cognition produced the largest impact, followed by hearing and sleep with similar impacts, energy, and relationships. This ordering offers information for bolt-on selection, with hearing and cognition appearing as the most important. The weight placed on the different health problems is not constant across severity levels between bolt-ons. Conclusions Pairwise choices provide a cost-effective approach of generating information on preferences to support bolt-on selection.

scholarly journals Locating microseismic sources with a single seismometer channel using coda wave interferometry

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. A19-A24 ◽  
Author(s):  
Youqian Zhao ◽  
Andrew Curtis ◽  
Brian Baptie
Keyword(s):  
Single Channel ◽  
Cost Effective ◽  
Coda Wave ◽  
Probabilistic Framework ◽  
Data Set ◽  
Cost Effective Method ◽  
Potential Applications ◽  
The Impact ◽  
Coda Wave Interferometry ◽  
Selection Of

A novel source location method based on coda wave interferometry (CWI) was applied to a microseismic data set of mining-induced events recorded in Nottinghamshire, England. CWI uses scattered waves in the coda of seismograms to estimate the differences between two seismic states. We used CWI to estimate the distances between pairs of earthquake locations, which are then used jointly to determine the relative location of a cluster of events using a probabilistic framework. We evaluated two improvements to this location technique: These account for the impact of a large difference in the dominant wavelength of a recording made on different instruments, and they standardize the selection of parameters to be used when implementing the method. Although the method has been shown to produce reasonable estimates on larger earthquakes, we tested the method for microseismic events with shorter distinguishable codas in recorded waveforms, and hence, fewer recorded scattered waves. The earthquake location results are highly consistent when using different individual seismometer channels, showing that it is possible to locate event clusters with a single-channel seismometer. We thus extend the potential applications of this cost-effective method to seismic events over a wider range of magnitudes.

scholarly journals Urine Metabolites for Estimating Daily Intake of Nicotine From Cigarette Smoking

2019 ◽  
Vol 22 (2) ◽  
pp. 288-292 ◽  
Author(s):  
Neal L Benowitz ◽  
Gideon St. Helen ◽  
Natalie Nardone ◽  
Lisa Sanderson Cox ◽  
Peyton Jacob
Keyword(s):  
Daily Intake ◽  
Cost Effective ◽  
Nicotine Exposure ◽  
Strongly Correlated ◽  
Urine Metabolites ◽  
Nicotine Intake ◽  
The Impact ◽  
Slow Metabolizers ◽  
Selection Of ◽  
Research Studies

Abstract Introduction Accurate measurement of nicotine exposure from cigarette smoke is important in studying disease risk and level of dependence. Urine total nicotine equivalents, the molar sum of nicotine and six metabolites (NE7), accounts for more than 90% of a nicotine dose and is independent of individual metabolic differences. However, measuring NE7 is technically difficult and costly. We compared NE7, the gold standard of nicotine intake, with different combinations of fewer urinary nicotine metabolites. We also examined the impact of individual differences in nicotine metabolic rate, sex, and race on strength of association with NE7. Methods Urine samples from 796 daily smokers, who participated across five clinical studies, were assayed for nicotine and/or metabolites. Associations with NE7 were assessed by regression and Bland–Altman analyses. Results Overall, the molar sum of urine [cotinine + 3′-hydroxycotinine (3HC)] (NE2) and [nicotine + 
cotinine + 3HC] (NE3) were strongly correlated with NE7 (r = .97 and .99, respectively). However, in slow metabolizers NE2 was less predictive of NE7, whereas NE3 was equally robust. Urine total cotinine was also strongly correlated with NE7 (r = .87). Conclusions Urine NE3 is a robust biomarker of daily nicotine intake, independently of individual metabolic differences, whereas NE2 is less accurate in slow metabolizers. Our findings inform the selection of more rigorous and cost-effective measures to assess nicotine exposure in tobacco research studies. Implications The molar sum of urine total nicotine, cotinine and 3HC (NE3) is a robust biomarker of daily nicotine intake, independently of individual metabolic differences, and performs as well as measuring seven nicotine metabolites (NE7). The sum of cotinine and 3HC (NE2) is less accurate in slow metabolizers. Our findings inform the selection of more rigorous and cost-effective measures to assess nicotine exposure in tobacco research studies.

Tools and Methods for Internal Pipe Coating Evaluation for Gas Transmission Systems

2012 ◽  
Author(s):  
K. K. Botros ◽  
M. Piazza ◽  
D. Abayarathna
Keyword(s):  
Life Cycle Cost ◽  
Cost Effective ◽  
Sound Design ◽  
Pressure Losses ◽  
Pipeline Systems ◽  
Consistent Manner ◽  
Transmission Pipeline ◽  
And Performance ◽  
The Impact ◽  
Selection Of

The option of internally coating a new pipeline, or a section of an existing pipeline has emerged in recent years as competition in the energy marketplace grows more intense and coating technologies have advanced from 100% solvent-base to 100% dry-based. Internally coated pipes would mean additional capital cost, but will result in lower pressure losses, hence lower compression power, lower fuel consumption and lower emission. Therefore, there is a trade-off that needs to be assessed, which is the subject of the present paper. The present paper first provides a proposed standardized method to report the internal wall roughness parameters that could be used to compare bare vs. different coating technologies in a consistent manner. The second part of the paper focuses on evaluating the impact and performance of internal coatings on flow efficiency in energy transmission pipeline systems. A tool and methods were developed to evaluate all of the various options specific to internal pipe coating (including bare pipe option) using a Life Cycle Cost (LCC) economic tool developed for this purpose. The incremental Cumulative Present Value Cost of Service (iCPVCOS) associated with the application of the various coating technologies, as well as quantification of the relative benefits of each compared to a bare pipe, are the main outcome of the tool. This provides an impetus to sound design and selection of the most cost effective technology for internally coating the pipes, whether for new or existing pipeline systems. Examples of various scenarios involving a 2900 km pipeline coated using different internal coating technologies are discussed.

Design of Steel Lazy Wave Riser for External Turret Moored FPSO

2019 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Water Depth ◽  
Optimal Solution ◽  
Cost Effective ◽  
Fatigue Performance ◽  
Effective Solution ◽  
Field Development ◽  
Riser Design ◽  
Preferred Solutions ◽  
Design Challenges ◽  
Selection Of

Abstract The external turret moored Floating Production Storage and Offloading system (FPSO) is one of the preferred solutions for deepwater fields in mild to moderate environments and far away from existing pipeline infrastructures. This paper presents a design of steel lazy wave riser (SLWR) system for an external turret moored FPSO in the water depth of 1,500 meter. The design challenges and feasibility are discussed. Due to the complexity of SLWR geometry, a systematic configuration approach is introduced to achieve the desired riser extreme and fatigue performance target, as well as external turret layout. The study includes the standardized FPSO, the selection of turret configuration, and riser design. The titanium taper stress joints and the interaction with turret structure are also studied. The study provides an optimal solution of the integrated turret, mooring and riser system. It concludes that external turret FPSO with SLWRs can be a feasible and cost effective solution for field development in mild to moderate environments.

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