Ice Gouge Reliability of Offshore Arctic Pipelines

2007 ◽  
Author(s):  
A. H. Younan ◽  
J. M. Hamilton ◽  
J. Weaver
Keyword(s):  
Traditional Approach ◽  
Relative Strength ◽  
First Year ◽  
Burial Depth ◽  
Buried Pipe ◽  
Element Analysis ◽  
Statistical Characterization ◽  
The Impact ◽  
Adequate Reliability

Offshore arctic pipelines must be designed with adequate reliability against damage or rupture due to the effects of ice features that gouge the seafloor. A common design approach is to bury the pipeline sufficiently deep to avoid contact by a gouging ice keel of a target rare return interval. The effects of sub-gouge soil displacements on pipe stress or strain are also assessed. It is implicitly assumed, in this traditional approach, that ice keels have infinite strength and momentum, so that gouge depths are not limited by ice keel failure and direct contact of ice on pipe results in rupture. However, many first-year ice features may not be strong enough to gouge the soil to the extreme gouge depths. Considering the high cost of incremental pipeline burial depth, it may be desirable to account for limits imposed on extreme gouge depth by soil resistance. Introducing these limits, however, gives rise to additional uncertainty and requires the development of a reliability framework to assess the consequences of direct ice contact on the buried pipe. This paper presents a methodology for evaluating the probability of ice gouging non-performance of a pipeline while explicitly accounting for the ability of the seabed soil to limit ice gouge depth based on the relative strength of soil and ice keel. Non-performance is defined either as ice contact on the pipe or exceedence of some level of acceptable pipe strain when contacted by ice. A three-step approach is followed through the use of nonlinear finite element analysis to estimate pipeline capacity, the statistical characterization of demand from ice gouging events, and the development of a reliability framework combining demand and capacity. Parameters governing the capacity of the pipeline are identified, the sensitivity of the pipeline reliability to various parameters is investigated, and the impact of allowing ice contact on pipeline reliability is presented. Relative merits and risks of allowing ice contact are discussed in the context of pipeline reliability. The presented results and discussions are believed to be of significant help in the development of burial depth criteria for future offshore arctic pipelines, and certainly in the reassessment of existing ones.

Hiding resonant planets behind a big friend

2020 ◽  
Author(s):  
Laetitia Rodet ◽  
Dong Lai
Keyword(s):  
Theoretical Study ◽  
Giant Planet ◽  
Relative Strength ◽  
Indirect Detection ◽  
Mean Motion ◽  
Formation And Evolution ◽  
The Impact ◽  
Mean Motion Resonance

<p class="western" align="justify">The characterization of the interplay between the inner and outer parts of planetary systems has long been impractical due to the separated detection ranges of the corresponding observation techniques. However, this gap is closing thanks to the technical improvements of the instruments and the longer observational baselines, and statistical insights are already within reach on the impact of cold Jupiters on super Earths. In this talk, I would like to present a theoretical study on the influence of an external giant planet misaligned with inner resonant planets, within the circular restricted problem. The behavior of the system depends on the relative strength between the coupling of the planets and the perturbations from the outer body. We demonstrated that mean-motion resonance strengthens the inner coupling and is very resilient to the perturbation, surviving periodic relative inclination increases of tens of degrees between the inner planets. This study has applications for the indirect detection of exoplanets, as well as the understanding of their formation and evolution, in particular the role of mean-motion resonance and relative inclinations.</p>

A Statistical Characterization of the Effects and Interactions of Small and Large Mistuning on Multistage Bladed Disks

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Eric Kurstak ◽  
Kiran D'Souza
Keyword(s):  
Modern Technology ◽  
Forced Response ◽  
Response Analysis ◽  
Statistical Characterization ◽  
System A ◽  
Multistage System ◽  
Stage System ◽  
Random Patterns ◽  
The Impact

Abstract As turbomachinery systems continue to push the limits of modern technology, the modeling techniques being developed also continue to push modern computational limits. While modeling the pristine system during the design process is important, it is equally important to model behavior of mistuned systems, due to wear or manufacturing processes. This work carries out a statistical analysis on a two-stage system consisting of integrally bladed rotors. Various forms of large geometric mistuning, such as missing mass, bends, and dents, are considered. These forms of large mistuning are based on previously reported damage seen in actual engines that have ingested volcanic ash. This work also aims to investigate the interaction of these large mistuned systems with various levels of small mistuning to further understand this complex interaction. For every case studied, a reduced-order model (ROM) will be constructed that includes the effects of small and large mistuning. Large mistuning will only be applied to a single sector of a single stage. Random patterns of small mistuning will be applied to each case of large mistuning after which a modal analysis and a forced response analysis are run. By observing the energy distribution of each mode for the mistuned system, a qualitative trend can be created between various types and levels of large mistuning and the impact they have on changing the dynamics of the multistage system. The amplification factors from the forced response analyses help in understanding the impact small mistuning has when coupled with large mistuning and when the effects of small mistuning dominate over the large mistuning effects.

scholarly journals Improving the Learning of Mechanics Through Augmented Reality

2021 ◽  
Author(s):  
Clarissa Hedenqvist ◽  
Mario Romero ◽  
Ricardo Vinuesa
Keyword(s):  
Augmented Reality ◽  
User Study ◽  
Physical Phenomenon ◽  
First Year ◽  
Statistical Characterization ◽  
Qualitative And Quantitative ◽  
Post Test ◽  
Visualization Technology ◽  
Larger Sample

AbstractThis study investigates to which extent students’ understanding of the physical phenomenon of torque can be improved through the use of visualization technology, in particular of augmented reality (AR). The students in the first-year course Mechanics I at KTH participated in the study by taking two tests on torque. In between those tests, a subgroup of students participated in a user study where they used an AR application to solve problems regarding torque. The results of the pre-test and the post-test indicate that the subgroup who used the app improved their understanding of torque to a greater extent than the ones who did not use the app. However, a larger sample space would be required to obtain a complete statistical characterization of the reported (qualitative and quantitative) improvement.

Application of Electron Probe Microanalysis to the Study of Geological and Planetary Materials

2001 ◽  
Vol 7 (2) ◽  
pp. 200-210 ◽  
Author(s):  
James J. McGee ◽  
Klaus Keil
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Trace Element Analysis ◽  
Light Element ◽  
Element Analysis ◽  
Analytical Instruments ◽  
The Impact ◽  
Geological Research ◽  
Planetary Materials

Abstract The impact of electron probe microanalysis on the study of geological and planetary materials has been tremendous. Electron microprobes evolved into routine analytical instruments in geological research laboratories as instrument capabilities improved and applications to geologic/planetary materials expanded. The contributions of electron probe microanalysis to the characterization of minerals, both terrestrial and extraterrestrial, and to other significant geological research, such as light element analysis, trace element analysis, and element mapping, is described.

A Statistical Characterization of the Effects and Interactions of Small and Large Mistuning on Multistage Bladed Disks

2019 ◽  
Author(s):  
Eric Kurstak ◽  
Kiran D’Souza
Keyword(s):  
Modern Technology ◽  
Forced Response ◽  
Response Analysis ◽  
Statistical Characterization ◽  
System A ◽  
Multistage System ◽  
Stage System ◽  
Random Patterns ◽  
The Impact

Abstract As turbomachinery systems continue to push the limits of modern technology, the modeling techniques being developed also continue to push modern computational limits. While modeling the pristine system during the design process is important, it is equally important to model behavior of mistuned systems, due to wear or manufacturing processes. This work carries out a statistical analysis on a two-stage system consisting of integrally bladed rotors. Various forms of large geometric mistuning, such as missing mass, bends, and dents, are considered. These forms of large mistuning are based on previously reported damage seen in actual engines that have ingested volcanic ash. This work also aims to investigate the interaction of these large mistuned systems with various levels of small mistuning to further understand this complex interaction. For every case studied, a reduced order model will be constructed that includes the effects of small and large mistuning. Large mistuning will only be applied to a single sector of a single stage. Random patterns of small mistuning will be applied to each case of large mistuning after which a modal analysis and a forced response analysis are run. By observing the energy distribution of each mode for the mistuned system, a qualitative trend can be created between various types and levels of large mistuning and the impact they have on changing the dynamics of the multistage system. The amplification factors from the forced response analyses help in understanding the impact small mistuning has when coupled with large mistuning and when the effects of small mistuning dominate over the large mistuning effects.

Statistical characterization of the impact strengths of vapor-grown carbon nanofiber/vinyl ester nanocomposites using a central composite design

2012 ◽  
Vol 128 (2) ◽  
pp. 1070-1080 ◽  
Author(s):  
Glenn W. Torres ◽  
Sasan Nouranian ◽  
Thomas E. Lacy ◽  
Hossein Toghiani ◽  
Charles U. Pittman ◽  
...  
Keyword(s):  
Central Composite Design ◽  
Vinyl Ester ◽  
Carbon Nanofiber ◽  
Statistical Characterization ◽  
The Impact ◽  
Central Composite ◽  
Vapor Grown Carbon Nanofiber

The Need to Belong and the Relationship Between Loneliness and Health

2014 ◽  
Vol 22 (4) ◽  
pp. 194-201 ◽  
Author(s):  
Freda-Marie Hartung ◽  
Britta Renner
Keyword(s):  
Individual Differences ◽  
Social Isolation ◽  
Social Situation ◽  
First Year ◽  
Health State ◽  
Need To Belong ◽  
First Year University ◽  
Perceived Social Isolation ◽  
The Impact ◽  
The Relationship

Humans are social animals; consequently, a lack of social ties affects individuals’ health negatively. However, the desire to belong differs between individuals, raising the question of whether individual differences in the need to belong moderate the impact of perceived social isolation on health. In the present study, 77 first-year university students rated their loneliness and health every 6 weeks for 18 weeks. Individual differences in the need to belong were found to moderate the relationship between loneliness and current health state. Specifically, lonely students with a high need to belong reported more days of illness than those with a low need to belong. In contrast, the strength of the need to belong had no effect on students who did not feel lonely. Thus, people who have a strong need to belong appear to suffer from loneliness and become ill more often, whereas people with a weak need to belong appear to stand loneliness better and are comparatively healthy. The study implies that social isolation does not impact all individuals identically; instead, the fit between the social situation and an individual’s need appears to be crucial for an individual’s functioning.

The Analyses of Learning Strategies in English as a Second Language: Theoretical Classification and Measurement Test

2020 ◽  
Vol 4 (2) ◽  
pp. 118-129
Author(s):  
Asti Gumartifa ◽  
◽  
Indah Windra Dwie Agustiani
Keyword(s):  
Language Learning ◽  
Learning Outcomes ◽  
Learning Strategies ◽  
Learning Process ◽  
English Learners ◽  
English Language ◽  
Point Of View ◽  
Effective Learning ◽  
The Impact

Gaining English language learning effectively has been discussed all years long. Similarly, Learners have various troubles outcomes in the learning process. Creating a joyful and comfortable situation must be considered by learners. Thus, the implementation of effective learning strategies is certainly necessary for English learners. This descriptive study has two purposes: first, to introduce the classification and characterization of learning strategies such as; memory, cognitive, metacognitive, compensation, social, and affective strategies that are used by learners in the classroom and second, it provides some questionnaires item based on Strategy of Inventory for Language Learning (SILL) version 5.0 that can be used to examine the frequency of students’ learning strategies in the learning process. The summary of this study explains and discusses the researchers’ point of view on the impact of learning outcomes by learning strategies used. Finally, utilizing appropriate learning strategies are certainly beneficial for both teachers and learners to achieve the learning target effectively.

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