scholarly journals Estimating degradation growth rate and time of component replacement from limited inspection data using mixed-effects modelling

2022 ◽  
Vol 388 ◽  
pp. 111618
Author(s):  
Mikko I. Jyrkama ◽  
Mahesh D. Pandey ◽  
Ming Li
Keyword(s):  
Growth Rate ◽  
Mixed Effects ◽  
Inspection Data ◽  
Component Replacement

scholarly journals Evaluation of Rhodotorula growth on solid substrate via a linear mixed effects model

2011 ◽  
Vol 29 (No. 4) ◽  
pp. 400-410 ◽  
Author(s):  
T. Krulikovská ◽  
E. Jarošová ◽  
P. Patáková
Keyword(s):  
Growth Rate ◽  
Confidence Intervals ◽  
Solid Substrate ◽  
Mixed Effects ◽  
Repeated Measurements ◽  
Mixed Effects Model ◽  
Cultivation Conditions ◽  
Linear Mixed Effects Model ◽  
Linear Mixed Effects ◽  
The Impact

The growth of Rhodotorula glutinis and Rhodotorula mucilaginosa was studied under optimal and stress cultivation conditions at 10°C and 20°C for 14 days. The method of image analysis was used to determine the size of colonies. The linear mixed effects model implemented in the statistical program S-PLUS was applied to analyse the repeated measurements. Two-phase kinetics was confirmed and the mean growth rates in the second linear phase under various stress conditions were estimated. The results indicated a higher growth rate of R. mucilaginosa than was that of R. glutinis under all cultivation conditions. The highest growth rate of was observed during the cultivation of R. mucilaginosa in media with 2% of NaCl at 20°C. The impact of neglecting the fact that repeated data are not independent and using the classical regression model instead of the mixed effects model was demonstrated through the comparison of the confidence intervals for the parameters based on both approaches. While the point estimates of the corresponding parameters were similar, the width of the confidence intervals differed substantially.

Utilizing In-Line Inspection Data and Structural Reliability Analysis to Set a Defendable Corrosion Re-Assessment Interval

2006 ◽  
Author(s):  
Ryan Sporns ◽  
Steven Bott ◽  
David Playdon
Keyword(s):  
Growth Rate ◽  
Software Package ◽  
Structural Reliability ◽  
Probability Of Failure ◽  
Simulation Based ◽  
Reliability Methods ◽  
Inspection Data ◽  
Integrity Analysis ◽  
Operation Characteristics ◽  
Pipeline Corrosion

A quantitative pipeline integrity analysis based on structural-reliability methods has been used to establish corrosion re-assessment intervals from in-line inspection data. This process, as implemented in a simulation-based software package, incorporates in line inspection (ILI) data, physical and operation characteristics of the pipeline, corrosion growth rate projections, and the uncertainties inherent in this information, to estimate the probability of failure (POF) as a function of time. Using this approach, the POF value is calculated on a joint-by-joint basis and the calculated values are then compared with an acceptable POF level to verify the integrity of each joint in any given year. Based on this information a re-assessment interval is established and selected joints are targeted for excavation and repair to ensure that the acceptable POF level is not exceeded.

A Practical Application to Calculating Corrosion Growth Rates by Comparing Successive ILI Runs From Different ILI Vendors

2010 ◽  
Author(s):  
Kevin Spencer ◽  
Shahani Kariyawasam ◽  
Cathy Tetreault ◽  
Jon Wharf
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Management Program ◽  
Management Decision ◽  
Pipeline System ◽  
Data Sets ◽  
Simple Method ◽  
Integrity Management ◽  
Inspection Data ◽  
Over Time

Corrosion growth rates are an essential input into an Integrity Management Program but they can often be the largest source of uncertainty and error. A relatively simple method to estimate a corrosion growth rate is to compare the size of a corrosion anomaly over time and the most practical way to do this for a whole pipeline system is via the use of In-Line Inspection (ILI). However, the reported depth of the anomaly following an ILI run contains measurement uncertainties, i.e., sizing tolerances that must be accounted for in defining the uncertainty, or error associated with the measured corrosion growth rate. When the same inspection vendor performs the inspections then proven methods exist that enable this growth error to be significantly reduced but these methods include the use of raw inspection data and, specialist software and analysis. Guidelines presently exist to estimate corrosion growth rates using inspection data from different ILI vendors. Although well documented, they are often only applicable to “simple” cases, pipelines containing isolated corrosion features with low feature density counts. As the feature density or the corrosion complexity increases then different reporting specifications, interaction rules, analysis procedures, sizing models, etc can become difficult to account for, ultimately leading to incorrect estimations or larger uncertainties regarding the growth error. This paper will address these issues through the experiences of a North American pipeline operator. Accurately quantifying the reliability of pipeline assets over time requires accurate corrosion growth rates and the case study will demonstrate how the growth error was significantly reduced over existing methodologies. Historical excavation and recoat information was utilized to identify static defects and quantify systemic bias between inspections. To reduce differences in reporting and the analyst interpretation of the recorded magnetic signals, novel analysis techniques were employed to normalize the data sets against each other. The resulting uncertainty of the corrosion growth rates was then further reduced by deriving, and applying a regression model to reduce the effect of the different sizing models and the identified systemic bias. The reduced uncertainty ultimately led to a better understanding of the corrosion activity on the pipeline and facilitated a better integrity management decision process.

Methodology for Comparing Field Applied Liquid Epoxy and Hot Bituminous Tape Coating Repairs Using Inline Inspection Data

2016 ◽  
Author(s):  
Haralampos Tsaprailis ◽  
Mona Abdolrazaghi ◽  
Jeff Liang
Keyword(s):  
Decision Making ◽  
Growth Rate ◽  
Nondestructive Examination ◽  
Environment Temperature ◽  
Data Assessment ◽  
Corrosion Defects ◽  
External Corrosion ◽  
Inspection Data ◽  
Operational Data ◽  
Corrosion Feature

In this paper, pipelines with similar parameters (e.g., diameter, environment, temperature of the product, etc.) are used to compare the effectiveness of field repair coatings (i.e., liquid epoxy and tape coating systems) against external corrosion. Liquid epoxy and tape coating systems are compared based on number of corrosion features, severity, morphology and distribution of features over depth and length. Once corrosion defects are assessed in the field and a repair coating is applied, In-Line Inspection (ILI) tools can detect and size the corrosion features under these coatings. If the corrosion feature is growing, the growth can be detected and measured using ILI data assessment. In this paper, data from both field nondestructive examination (NDE) and ILI measurements collected from 1996 to 2013 are used to assess the corrosion growth rate (CGR) under both types of repair coatings. The CGR with respect to depth is compared for both liquid epoxy and tape coatings and then normalized by the number of corrosion features over the segment. In addition, the effectiveness of cathodic protection was evaluated at the locations of the assessed repair coating. Ultimately, this paper provides useful information to pipeline operators for decision making regarding the choice of repair coatings based on operational data collected over 14 years.

The threshold energy for atom displacement in fcc metals

1990 ◽  
Vol 48 (4) ◽  
pp. 530-531
Author(s):  
Wilfried Sigle ◽  
Matthias Hohenstein ◽  
Alfred Seeger
Keyword(s):  
Growth Rate ◽  
Elevated Temperatures ◽  
Threshold Energy ◽  
Dislocation Loops ◽  
Absolute Minimum ◽  
Voltage Electron ◽  
Atom Displacement ◽  
Electron Microscopes ◽  
Fcc Metal

Prolonged electron irradiation of metals at elevated temperatures usually leads to the formation of large interstitial-type dislocation loops. The growth rate of the loops is proportional to the total cross-section for atom displacement,which is implicitly connected with the threshold energy for atom displacement, Ed . Thus, by measuring the growth rate as a function of the electron energy and the orientation of the specimen with respect to the electron beam, the anisotropy of Ed can be determined rather precisely. We have performed such experiments in situ in high-voltage electron microscopes on Ag and Au at 473K as a function of the orientation and on Au as a function of temperature at several fixed orientations.Whereas in Ag minima of Ed are found close to <100>,<110>, and <210> (13-18eV), (Fig.1) atom displacement in Au requires least energy along <100>(15-19eV) (Fig.2). Au is thus the first fcc metal in which the absolute minimum of the threshold energy has been established not to lie in or close to the <110> direction.

Modeling Intraindividual Variability in Three-Level Multilevel Models

Methodology ◽  
2018 ◽  
Vol 14 (3) ◽  
pp. 95-108 ◽  
Author(s):  
Steffen Nestler ◽  
Katharina Geukes ◽  
Mitja D. Back
Keyword(s):  
Multilevel Model ◽  
Multilevel Models ◽  
Mixed Effects ◽  
Repeated Measurements ◽  
Scale Model ◽  
Suggested Approach ◽  
Psychological Study ◽  
Level Data ◽  
Ecological Momentary ◽  
Momentary Assessment

Abstract. The mixed-effects location scale model is an extension of a multilevel model for longitudinal data. It allows covariates to affect both the within-subject variance and the between-subject variance (i.e., the intercept variance) beyond their influence on the means. Typically, the model is applied to two-level data (e.g., the repeated measurements of persons), although researchers are often faced with three-level data (e.g., the repeated measurements of persons within specific situations). Here, we describe an extension of the two-level mixed-effects location scale model to such three-level data. Furthermore, we show how the suggested model can be estimated with Bayesian software, and we present the results of a small simulation study that was conducted to investigate the statistical properties of the suggested approach. Finally, we illustrate the approach by presenting an example from a psychological study that employed ecological momentary assessment.

Extremism Leads to Ostracism

2020 ◽  
Vol 51 (3) ◽  
pp. 149-156
Author(s):  
Andrew H. Hales ◽  
Kipling D. Williams
Keyword(s):  
Mixed Effects ◽  
Social Connection ◽  
Mixed Effects Modeling ◽  
Activist Groups

Abstract. Ostracism has been shown to increase openness to extreme ideologies and groups. We investigated the consequences of this openness-to-extremity from the perspective of potential ostracizers. Does openness-to-extremity increase one’s prospects of being ostracized by others who are not affiliated with the extreme group? Participants rated willingness to ostracize 40 targets who belong to activist groups that vary in the type of goals/cause they support (prosocial vs. antisocial), and the extremity of their actions (moderate vs. extreme). Mixed-effects modeling showed that people are more willing to ostracize targets whose group engages in extreme actions. This effect was unexpectedly stronger for groups pursuing prosocial causes. It appears openness-to-extremity entails interpersonal cost, and could increase reliance on the extreme group for social connection.

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