Academic literature on the topic 'Models of rupture (MOR)'
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Journal articles on the topic "Models of rupture (MOR)"
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Tiryaki, Sebahattin, Uğur Aras, Hülya Kalaycıoğlu, Emir Erişir, and Aytaç Aydın. "Predictive Models for Modulus of Rupture and Modulus of Elasticity of Particleboard Manufactured in Different Pressing Conditions." High Temperature Materials and Processes 36, no. 6 (July 26, 2017): 623–34. http://dx.doi.org/10.1515/htmp-2015-0203.
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AbstractDetermining the mechanical properties of particleboard has gained a great importance due to its increasing usage as a building material in recent years. This study aims to develop artificial neural network (ANN) and multiple linear regression (MLR) models for predicting modulus of rupture (MOR) and modulus of elasticity (MOE) of particleboard depending on different pressing temperature, pressing time, pressing pressure and resin type. Experimental results indicated that the increased pressing temperature, time and pressure in manufacturing process generally improved the mechanical properties of particleboard. It was also seen that ANN and MLR models were highly successful in predicting the MOR and MOE of particleboard under given conditions. On the other hand, a comparison between ANN and MLR revealed that the ANN was superior compared to the MLR in predicting the MOR and MOE. Finally, the findings of this study are expected to provide beneficial insights for practitioners to better understand usability of such composite materials for engineering applications and to better assess the effects of pressing conditions on the MOR and MOE of particleboard.
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Høibø, Olav, and Geir I. Vestøl. "Modelling the variation in modulus of elasticity and modulus of rupture of Scots pine round timber." Canadian Journal of Forest Research 40, no. 4 (April 2010): 668–78. http://dx.doi.org/10.1139/x10-021.
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Recovery from the forest-wood chain is directly influenced by how different qualities of logs are used. Logs used directly as load-carrying members in structures are products in which MOE (modulus of elasticity when bending) and MOR (modulus of rupture) are of great importance. To achieve a more optimal bucking process in the forest, models that enable such presorting of logs for quality are desirable. In all, 533 logs from 150 trees were sampled from 10 stands with different site indices and altitudes in southern Norway. Models were developed that predicted MOE and MOR by using different stand and tree characteristics. The MOR models were compared with a model including MOE alone and a model including both MOE and different tree characteristics. The study showed that it may be a good option to combine different tree and stand characteristics with MOE. MOE and the single-tree variables diameter at breast height and mean annual ring width at breast height most reduced the residual variance when MOR was modelled. The study also showed that it is possible to perform a coarse sorting by simple stand and single-tree characteristics.
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Villasante, Antonio, Guillermo Íñiguez-González, and Lluis Puigdomenech. "Comparison of various multivariate models to estimate structural properties by means of non-destructive techniques (NDTs) in Pinus sylvestris L. timber." Holzforschung 73, no. 4 (April 24, 2019): 331–38. http://dx.doi.org/10.1515/hf-2018-0103.
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AbstractThe predictability of modulus of elasticity (MOE), modulus of rupture (MOR) and density of 120 samples of Scots pine (Pinus sylvestrisL.) were investigated using various non-destructive variables (such as time of flight of stress wave, natural frequency of longitudinal vibration, penetration depth, pullout resistance, visual grading and concentrated knot diameter ratio), and based on multivariate algorithms, applying WEKA as machine learning software. The algorithms used were: multivariate linear regression (MLR), Gaussian, Lazy, artificial neural network (ANN), Rules and decision Tree. The models were quantified based on the root-mean-square error (RMSE) and the coefficient of determination (R2). To avoid model overfitting, the modeling was built and the results validated via the so-called 10-fold cross-validation. MLR with the “greedy method” for variable selection based on the Akaike information metric (MLRak) significantly reduced the RMSE of MOR and MOE compared to univariate linear regressions (ULR). However, this reduction was not significant for density prediction. The predictability of MLRak was not improved by any other of the tested algorithms. Specifically, non-linear models, such as multilayer perceptron, did not contribute any significant improvements over linear models. Finally, MLRak models were simplified by discarding the variables that produce the lowest RMSE increment. The resulted models could be even further simplified without significant RMSE increment.
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Vincent, Manon, and Isabelle Duchesne. "Modeling flexural properties in white spruce (Picea glauca) and jack pine (Pinus banksiana) plantation trees." Canadian Journal of Forest Research 44, no. 1 (January 2014): 82–91. http://dx.doi.org/10.1139/cjfr-2013-0312.
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Mixed models combining random coefficient effect and covariance patterns were used to investigate mechanical property variations in jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) trees. Modulus of elasticity (MOE) and modulus of rupture (MOR) were measured by conducting three-point bending tests on small defect-free samples selected from different radial positions and at a height of 2.5 m above ground within the stems. The objective of the paper was to build statistical predictive models describing the radial variations in stems for wood mechanical properties using easily measurable explanatory variables that are typically available in the wood manufacturing industry: distance from pith, tree height and diameter, and spacing. The explanatory variables integrated into the models explained MOE adequately, whereas MOR appeared harder to predict with only these variables and at this resolution. For white spruce, the best mixed-effects models explained 80% and 61% of the variation in MOE and MOR, respectively. For jack pine, it was 51% and 33% for the same response variables. These results are a step toward models that could be used in sawing simulation software designed to estimate the internal properties of sawlogs and, as a result, better predict lumber and pulp chip quality.
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Su, Zihua, Zhilin Jiang, Yi Liang, Bingzhen Wang, and Jianping Sun. "An artificial neural network model for predicting mechanical strength of bamboo-wood composite based on layups configuration." BioResources 17, no. 2 (April 25, 2022): 3265–77. http://dx.doi.org/10.15376/biores.17.2.3265-3277.
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The transportation application of the bamboo–wood composite container flooring (BWCCF) has increased considerably. However, materials would be destroyed in the process of common mechanical evaluation, resulting in a waste of resources. Therefore, this paper aims to design artificial neural network (ANN) models to predict mechanical strength of BWCCF. The modulus of rupture (MOR) and the modulus of elasticity (MOE) of BWCCF were predicted by ANN models based on layups configuration, including directions, densities, and thicknesses of 21-layer BWCCF in each layer. According to results, the mean absolute percentage errors (MAPE) and the correlation coefficient (R) were determined as 16.93% and 0.619 in prediction of MOR, and 10.10% and 0.709 in prediction of MOE, respectively. The results indicated that ANN can be applied to predict mechanical properties of BWCCF.
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Mansfield, Shawn D., Lazaros Iliadis, and Stavros Avramidis. "Neural network prediction of bending strength and stiffness in western hemlock (Tsuga heterophylla Raf.)." Holzforschung 61, no. 6 (November 1, 2007): 707–16. http://dx.doi.org/10.1515/hf.2007.115.
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Abstract The stiffness and strength, modulus of elasticity (MOE) and modulus of rupture (MOR), as well as density, moisture content, microfibril angle and diffraction pattern coefficient of variation of azimuthal intensity profile (ICV) was determined for 259 small clear specimens. These samples represent 38 old- and second-growth western hemlock (Tsuga heterophylla) trees harvested from several sites in coastal British Columbia, Canada. The data were analyzed by classic statistical regression techniques to reveal interrelations among the mechanical properties and the inherent wood properties. Simultaneously, the predictive power of artificial neural networks was evaluated with the same data set by employing several optimization techniques. Regression analysis of wood density and the flexural strength properties resulted in R2 of 0.172 and 0.332 for MOE and MOR, respectively. The most efficient network model proved to be far superior demonstrating correlation coefficients with models for MOE ranging between 0.693 and 0.750, and the corresponding MOR models ranging between 0.438 and 0.561 in all testing phases. It is apparent that neural networks have the potential and capacity to self-train and become powerful adaptive systems that can predict the strength and stiffness of wood samples. The neural network analysis also revealed the importance level of each independent variable on both MOE and MOR properties.
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Jia, Ru, Yurong Wang, Rui Wang, and Xu Chen. "Physical and Mechanical Properties of Poplar Clones and Rapid Prediction of the Properties by Near Infrared Spectroscopy." Forests 12, no. 2 (February 10, 2021): 206. http://dx.doi.org/10.3390/f12020206.
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In order to understand the physical and mechanical properties of poplar clones, and explore a method for their quick evaluation, the air dry density, modulus of rupture (MOR), modulus of elasticity (MOE), and compressive strength parallel to grains of three new bred poplar clones were explored and the prediction models with the highest accuracy were established by near infrared spectroscopy (NIRs). Clone 50 (Populus deltoides CL. ‘55/65′) had the highest air dry density, MOR, MOE, and compressive strength parallel to grains in the three clones. For clone 50 and 108 (Populus euramericana cv. ‘Guariento’), the mechanical properties of sapwood were better than those of heartwood, and the sapwood of clone 50 also had a better air dry density than that of heartwood. There were significant positive correlations between the air dry density and mechanical properties, with correlation coefficients above 0.68. Prediction models with better effects could be obtained by using information on the cross section for the air dry density and mechanical properties. First derivative+ Savitzky–Golay (S-G) smoothing methods were employed for the air dry density and MOR, and multiple scattering correction (MSC)+ S-G smoothing methods were used when establishing prediction models of MOE and compressive strength parallel to grains.
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Matoba, Tetsuya, Kei Sato, and Kensuke Egashira. "Mouse models of plaque rupture." Current Opinion in Lipidology 24, no. 5 (October 2013): 419–25. http://dx.doi.org/10.1097/mol.0b013e3283646e4d.
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Torquato, Luciane Paes, David Auty, Roger E. Hernández, Isabelle Duchesne, David Pothier, and Alexis Achim. "Black spruce trees from fire-origin stands have higher wood mechanical properties than those from older, irregular stands." Canadian Journal of Forest Research 44, no. 2 (February 2014): 118–27. http://dx.doi.org/10.1139/cjfr-2013-0164.
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In the eastern Canadian boreal forest, long fire return intervals lead to over 60% of stands having an irregular, uneven-aged structure, which is associated with slower growth. The aim of this study was to examine the effect of stand structure on the clear wood mechanical properties of black spruce (Picea mariana (Mill.) B.S.P.). A total of 128 trees were destructively sampled from stands of regular and irregular structure across Quebec, Canada. Nonlinear mixed-effects models were developed for each stand type to describe the variation in modulus of elasticity (MOE) and modulus of rupture (MOR) in small defect-free samples as functions of cambial age and annual ring width. Mechanical properties were strongly related to cambial age, with a smaller influence of ring width. After accounting for these variables, both MOE and MOR were higher in samples from stands of regular structure, although differences were less pronounced in the upper stem compared with breast height. The fixed effects of the models explained between 34% and 53% of the variation in mechanical properties. A higher incidence of mild compression wood in trees of layer origin may explain the observed differences between stand structures.
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Li, Chunxu, Yaoxiang Li, Yanzheng Zhao, Zheyu Zhang, and Zichun Wang. "Mechanical Property Prediction of Larix gmelinii Wood Based on Vis-Near-Infrared Spectroscopy." Forests 13, no. 12 (November 25, 2022): 1995. http://dx.doi.org/10.3390/f13121995.
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Larix gmelinii is the major tree species in Northeast China. The wood properties of different Larix gmelinii are quite different and under strong genetic controls, so it can be better improved through oriented breeding. In order to detect the longitudinal compressive strength (LCS), modulus of rupture (MOR) and modulus of elasticity (MOE) in real-time, fast and non-destructively, a prediction model of wood mechanical properties with high precision and stability is constructed based on visible-near-infrared spectroscopy (Vis-NIRS) technology. The featured wavelengths were selected with the algorithms of competitive adaptive reweighted sampling (CARS), successive projection algorithm (SPA), uninformative variable elimination (UVE), synergy interval partial least squares (SiPLS) and their combinations. The prediction models were then developed based on the partial least square regression (PLSR). The predictive ability of models was evaluated with coefficient of determination (R2) and root mean square error (RMSE). It indicated that CARS performed the best among the four methods examined in terms of wavelength-variable selection. The combined featured wavelength selecting method of SiPLS-CARS showed better performance than the single wavelength selection method. The optimal models of LCS, MOR and MOE are the SiPLS-CARS-PLSR model, with the R2 of the calibration set and the validation set are both greater than 0.99, and RMSE the smallest. The NIR optimal models for wood mechanical properties predictions has high predictive accuracy and good robustness.
Dissertations / Theses on the topic "Models of rupture (MOR)"
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Crabbé, Blandine. "Gradient damage models in large deformation." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX085/document.
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Les modèles d'endommagement à gradient, aussi dénommés modèles à champs de phases, sont désormais largement utilisés pour modéliser la rupture fragile et ductile, depuis l'initiation de l'endommagement jusqu'à la propagation d'une fissure. Cependant, la majorité des études disponibles dans la littérature ne concerne que le cadre des petites déformations, et très peu d'études poussées ont été menées afin d'étudier leur pertinence dans un contexte de grandes déformations. Ce serait pourtant d'un intérêt primordial, notamment pour l'industrie pneumatique, qui deviendrait alors capable de prédire plus précisément l'initiation de l'endommagement dans ses structures.Dans la première partie de ce travail, nous établissons des solutions analytiques d'évolution de l'endommagement (homogène et localisée) pour des matériaux visqueux, en petites et en grandes déformations. En petites déformations, les modèles rhéologiques de Maxwell et Poynting-Thomson sont étudiés, et en grandes déformations, les modèles de Maxwell et Zener sont choisis. Une étude sur l'évolution de l'endommagement dans un cas purement hyperélastique est aussi menée.A cette première partie analytique succède une partie numérique, qui détaille l'implémentation des modèles d'endommagement à gradient dans des codes éléments finis en grandes déformations. De même qu'en petites déformations, une stratégie de minimisation alternée est adoptée pour résoudre successivement les problèmes d'endommagement et de déplacement. Le matériau suit une loi de Mooney-Rivlin quasi-incompressible, et une méthode mixte en déplacement-pression est utilisée. Des tests en 2D et 3D sont effectués, qui mettent en évidence la capacité des modèles à initier de l'endommagement en grandes déformations.Les modèles d'endommagement utilisés pour la seconde partie ne sont cependant capables d'initier de l'endommagement que dans les zones où la déformation est importante, c'est-à-dire dans les zones de forte contrainte déviatorique. Il a toutefois été montré que certains matériaux polymères, quasi-incompressibles, s'endommagent dans les zones de forte pression hydrostatique. Par conséquent, la recherche et l'étude d'un modèle d'endommagement capable d'initier de l'endommagement dans les zones de forte pression, pour des matériaux quasi-incompressibles lorsqu'ils sont sains, fait l'objet d'une troisième partie.Enfin, la croissance brusque de cavités dans un matériau hyperélastique, appelée phénomène de cavitation, est étudiée, ainsi que son interaction avec l'endommagement. Dans un premier temps, nous considérons la cavitation comme une simple bifurcation hyperélastique d'un matériau néo-hookéen compressible isotrope, et déterminons l'expression analytique de l'élongation critique pour laquelle la cavitation fait son apparition. Dans un second temps, nous montrons qu'il y a une compétition entre la cavitation et l'endommagement, et qu'en fonction de la valeur du ratio des élongations critiques respectives pour chaque phénomène, deux types de rupture apparaissentGradient damage models, also known as phase-field models, are now widely used to model brittle and ductile fracture, from the onset of damage to the propagation of a crack in various materials. Yet, they have been mainly studied in the framework of small deformation, and very few studies aims at proving their relevance in a finite deformation framework. This would be more helpful for the tyre industry that deals with very large deformation problems, and has to gain insight into the prediction of the initiation of damage in its structures.The first part of this work places emphasis on finding analytical solutions to unidimensional problems of damaging viscous materials in small and large deformation.In all the cases, the evolution of damage is studied, both in the homogeneous and localised cases. Having such solutions gives a suitable basis to implement these models and validate the numerical results.A numerical part naturally follows the first one, that details the specificities of the numerical implementation of these non local models in large deformation. In order to solve the displacement and damage problems, the strategy of alternate minimisation (or staggered algorithm) is used. When solved on the reference configuration, the damage problem is the same as in small deformation, and consists in a bound constraint minimisation. The displacement problem is non linear, and a mixed finite element method is used to solve a displacement-pressure problem. A quasi-incompressible Mooney-Rivlin law is used to model the behaviour of the hyperelastic material. Various tests in 2D and 3D are performed to show that gradient damage models are perfectly able to initiate damage in sound, quasi-incompressible structures, in large deformation.In the simulations depicted above, it should be noted that the damage laws combined to the hyperelastic potential results in an initiation of damage that takes place in zones of high deformation, or in other words, in zones of high deviatoric stress. However, in some polymer materials, that are known to be quasi-incompressible, it has been shown that the initiation of damage can take place in zones of high hydrostatic pressure. This is why an important aspect of the work consists in establishing a damage law such that the material be incompressible when there is no damage, and the pressure play a role in the damage criterion. Such a model is exposed in the third part.Finally, the last part focuses on the cavitation phenomenon, that can be understood as the sudden growth of a cavity. We first study it as a purely hyperelastic bifurcation, in order to get the analytical value of the critical elongation for which cavitation occurs, in the case of a compressible isotropic neo-hookean material submitted to a radial displacement. We show that there is a competition between the cavitation phenomenon and the damage, and that depending on the ratio of the critical elongation for damage and the critical elongation for cavitation, different rupture patterns can appear
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Pulido, Nelson. "Constraints for Dynamic Models of the Rupture from Kinematic Source Inversion." 京都大学 (Kyoto University), 2000. http://hdl.handle.net/2433/181128.
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Cirella, Antonella <1977>. "Joint inversion of GPS and strong motion data for earthquake rupture models." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/865/.
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Hamesse, Charles. "Simultaneous Measurement Imputation and Rehabilitation Outcome Prediction for Achilles Tendon Rupture." Thesis, KTH, Robotik, perception och lärande, RPL, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231485.
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Achilles tendonbrott (Achilles Tendon Rupture, ATR) är en av de typiska mjukvävnadsskadorna. Rehabilitering efter sådana muskuloskeletala skador förblir en långvarig process med ett mycket variet resultat. Att kunna förutsäga rehabiliteringsresultat exakt är avgörande för beslutsfattande stöduppdrag. I detta arbete designar vi en probabilistisk modell för att förutse rehabiliteringsresultat för ATR med hjälp av en klinisk kohort med många saknade poster. Vår modell är tränad från början till slutet för att samtidigt förutsäga de saknade inmatningarna och rehabiliteringsresultat. Vi utvärderar vår modell och jämför med flera baslinjer, inklusive flerstegsmetoder. Experimentella resultat visar överlägsenheten hos vår modell över dessa flerstadiga tillvägagångssätt med olika dataimuleringsmetoder för ATR rehabiliterings utfalls prognos.Achilles Tendon Rupture (ATR) is one of the typical soft tissue injuries. Rehabilitation after such musculoskeletal injuries remains a prolonged process with a very variable outcome. Being able to predict the rehabilitation outcome accurately is crucial for treatment decision support. In this work, we design a probabilistic model to predict the rehabilitation outcome for ATR using a clinical cohort with numerous missing entries. Our model is trained end-to-end in order to simultaneously predict the missing entries and the rehabilitation outcome. We evaluate our model and compare with multiple baselines, including multi-stage methods. Experimental results demonstrate the superiority of our model over these baseline multi-stage approaches with various data imputation methods for ATR rehabilitation outcome prediction.
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Azizipesteh, Baglo Hamid Reza. "Effect of various mix parameters on the true tensile strength of concrete." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12560.
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The primary aim of this research was to develop a method for determining the true uniaxial tensile strength of concrete by conducting a series of cylinder splitting, modulus of rupture (MOR) and cylinder/cube compression tests. The main objectives were: • Critically reviewing previous published research in order to identify gaps in current knowledge and understanding, including theoretical and methodological contributions to the true uniaxial tensile strength of concrete. In order to maintain consistency and increase the reliability of the proposed methods, it is essential to review the literature to provide additional data points in order to add additional depth, breathe and rigor to Senussi's investigation (2004). • The design of self compacting concrete (SCC), normal strength concrete (NSC) and high strength concrete (HSC) mixes and undertaking lab-based experimental works for mixing, casting, curing and testing of specimens in order to establish new empirical evidence and data. • Analysing the data, presenting the results, and investigating the application of validity methods as stated by Lin and Raoof (1999) and Senussi (2004). • To draw conclusions including comparison with previous research and literature, including the proposal of new correction factors and recommendations for future research. 29 batches of NSC, 137 batches of HSC, 44 batches of fly ash SCC and 47 batches of GGBS SCC were cast and their hardened and fresh properties were measured. Hardened properties measured included: cylinder splitting strength, MOR, cylinder compressive strength and cube compressive strength. A variety of rheological tests were also applied to characterise the fresh properties of the SCC mixes, including: slump flow, T50, L-box, V-funnel, J-ring and sieve stability. Cylinders were also visually checked after splitting for segregation. The tensile strength of concrete has traditionally been expressed in terms of its compressive strength (e.g. ft = c x c f ). Based on this premise, extensive laboratory testing was conducted to evaluate the tensile strength of the concretes, including the direct tension test and the indirect cylinder splitting and MOR tests. These tests however, do not provide sufficiently accurate results for the true uniaxial tensile strength, due to the results being based upon different test methods. This shortcoming has been overcome by recently developed methods reported by Lin and Raoof (1999) and Senussi (2004) who proposed simple correction factors for the application to the cylinder splitting and MOR test results, with the final outcome providing practically reasonable estimates of the true uniaxial tensile strength of concrete, covering a wide range of concrete compressive strengths 12.57 ≤ fc ≤ 93.82 MPa, as well as a wide range of aggregate types. The current investigation has covered a wide range of ages at testing, from 3 to 91 days. Test data from other sources has also been applied for ages up to 365 days, with the test results reported relating to a variety of mix designs. NSC, SCC and HSC data from the current investigation has shown an encouraging correlation with the previously reported results, hence providing additional wider and deeper empirical evidence for the validity of the recommended correction factors. The results have also demonstrated that the type (size, texture and strength) of aggregate has a negligible effect on the recommended correction factors. The concrete age at testing was demonstrated to have a potentially significant effect on the recommended correction factors. Altering the cement type can also have a significant effect on the hardened properties measured and demonstrated practically noticeable variations on the recommended correction factors. The correction factors proved to be valid regarding the effects of incorporating various blended cements in the HSC and SCC. The NSC, HSC and SCC showed an encouraging correlation with previously reported results, providing additional support, depth, breadth and rigor for the validity of the correction factors recommended.
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Mikami, Naoya. "Source Processes and Dynamic Rupture Models of Three Inland Earthquakes in the Northwestern Chubu District, Central Honshu Japan." 京都大学 (Kyoto University), 1992. http://hdl.handle.net/2433/168831.
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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものであるKyoto University (京都大学)
0048
新制・論文博士
博士(理学)
乙第7854号
論理博第1177号
新制||理||784(附属図書館)
UT51-92-K354
(主査)教授 尾池 和夫, 教授 安藤 雅孝, 教授 入倉 孝次郎
学位規則第4条第2項該当
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Ragon, Théa. "Études des incertitudes dans l’imagerie de la rupture sismique." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR4023.
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Les séismes rompent des failles inaccessibles situées à plusieurs kilomètres sous la surface terrestre. Alors, comment les comprendre puisque l’on ne peut les observer directement ? Notre seul recours est d’ausculter le globe terrestre depuis sa surface. Hélas, la quantité, la variété et la qualité de ces observations superficielles sont insuffisantes pour caractériser ces phénomènes complexes, et l’image des séismes que nous dressons est altérée par de nombreuses approximations. Ces approximations sont souvent nécessaires sous peine de ne pouvoir modéliser les séismes. Elles dérivent des limites de nos observations, de notre connaissance sommaire de la physique du globe terrestre, et des procédures de modélisation choisies. L’imperfection de nos modèles questionne notre capacité à reproduire la réalité de la rupture sismique, et peut remettre en cause notre compréhension des mécanismes qui la régissent. Notre quête de réalisme ne peut donc que s’accompagner d’une analyse exhaustive et détaillée des incertitudes qui corrompent potentiellement l’imagerie des séismes, ainsi que nos interprétations. Bien que les erreurs de mesures soient généralement connues et prises en compte, les autres approximations sont souvent négligées. Dans cette thèse, nous montrons que le manque de réalisme de notre description de l’intérieur du globe influence les modèles de séismes, surtout lorsque ces derniers ont une magnitude importante. Nous nous intéressons particulièrement à deux sources d’approximations majeures : l’architecture des failles, et la complexité temporelle des processus en jeu sur celles-ci. Deux méthodes sont présentées, qui permettent d’estimer, et de prendre en compte, les incertitudes dérivant de ces approximations dans les procédures de modélisation. Nous montrons que l’introduction de telles incertitudes, et d'autres incertitudes potentielles, est nécessaire pour imager des modèles de séismes fiables et réalistes. Nos résultats s’appuient sur l’utilisation de méthodes d’imagerie probabilistes, qui permettent d’analyser la diversité et l’hétérogénéité des modèles possibles. Nous montrons qu’une nouvelle génération de modèles sismiques est possible, plus réalistes que les modèles actuels, parce que reflétant notre méconnaissance du système TerreHow can we study earthquakes, these complex phenomenon occurring so deep under our feet that we cannot observe them directly? One unfortunate aspect of the problem is that we have to rely on measurements acquired at the surface of the Earth. These observations are incomplete, and the imagery of earthquakes is subject to biases induced by numerous approximations. Most of these approximations cannot be avoided, and stem from the poor resolution of the measurements, the inherent lack of knowledge of the physics of the Earth interior, and the bias induced by our modeling procedures. The imperfections of our models question our ability to robustly investigate earthquakes rupture, and thus to understand the physics driving them. The quest for robust images needs a thorough and exhaustive examination of the uncertainties that potentially corrupt the modeling procedure and its results, at least not to interpret improbable characteristics. Although measurement errors are usually accounted for, other kinds of approximations are overlooked. Here, we show that the impact of our simplified description of the Earth’s interior on earthquake models is significant, especially for the events with a large magnitude. We concentrate on two main sources of approximation: the architecture of seismogenic faults, and the temporal complexity of seismic and aseismic processes at play on these faults. We present two methodological developments allowing to estimate and account for uncertainties deriving from these approximations in modeling procedures. In particular, we show that introducing the uncertainties deriving from our approximation of the Earth’s physics is necessary to infer robust and realistic earthquake source models. Our analyses is supported by the use of probabilistic modeling approaches, allowing to explore the diversity and uncertainties of possible models
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May, David. "The TLC Method for Modeling Creep Deformation and Rupture." Honors in the Major Thesis, University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1620.
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This thesis describes a novel new method, termed the Tangent-Line-Chord (TLC) method, that can be used to more efficiently model creep deformation dominated by the tertiary regime. Creep deformation is a widespread mechanical mode of failure found in high-stress and temperature mechanical systems. To accurately simulate creep and its effect on structures, researchers utilize finite element analysis (FEA). General purpose FEA packages require extensive amounts of time and computer resources to simulate creep softening in components because of the large deformation rates that continuously evolve. The goal of this research is to employ multi-regime creep models, such as the Kachanov-Rabotnov model, to determine a set of equations that will allow creep to be simulated using as few iterations as possible. The key outcome is the freeing up of computational resources and the saving of time. Because both the number of equations and the value of material constants within the model change depending on the approach used, programming software will be utilized to automate this analytical process. The materials being considered in this research are mainly generic Ni-based superalloys, as they exhibit creep responses that are dominated by secondary and tertiary creep.B.S.M.E.
Bachelors
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering
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Di, Donfrancesco Fabrizio. "Reduced Order Models for the Navier-Stokes equations for aeroelasticity." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS603.
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Le coût d’une simulation numérique aéroélastique peut devenir trop onéreuse lorsque une analyse paramétrique à haut fidélité est requise. Dans ce contexte, des Modèles d'Ordre Réduit (MOR) ont été développés en vue de réduire le coût de calcul des simulations numériques en préservant un haut niveau de précision. Ce travail de thèse porte sur la construction d'un MOR pour les équations de Navier-Stokes en tenant compte d'un maillage déformable dans le cas d'une application aéroélastique. Une base modale pour l'écoulement est obtenue via la Décomposition Orthogonale aux valeurs propres et une projection Galerkin est utilisée pour réduire le système d'équations de la mécanique des fluides. Pour pouvoir prendre en compte les non-linéarités des équation de Navier-Stokes une méthode de projection masquée est mise en œuvre et évaluée pour différent cas test avec maillage fixe. Le MOR est ensuite adapté pour prendre en compte des maillages déformables. Finalement, une méthode réduite spectrale en temps (ROTSM) a été formulée afin de répondre aux problèmes de stabilité qui concernent le MORs avec projection dans le domaine de la mécanique des fluides. Une évaluation du MOR obtenu est ensuite menée sur des études paramétriques pour des applications aéroélastiquesThe numerical prediction of aeroelastic systems responses becomes unaffordable when parametric analyses with high-fidelity CFD are required. Reduced order modeling (ROM) methods have therefore been developed in view of reducing the costs of the numerical simulations while preserving a high level of accuracy. The present thesis focuses on the family of projection based methods for the compressible Navier-Stokes equations involving deforming meshes in the case of aeroelastic applications. A vector basis obtained by Proper Orthogonal Decomposition (POD) combined to a Galerkin projection of the system equations is used in order to build a ROM for fluid mechanics. Masked projection approaches are therefore implemented and assessed for different test cases with fixed boundaries in order to provide a fully nonlinear formulation for the projection-based ROMs. Then, the ROM is adapted in the case of deforming boundaries and aeroelastic applications in a parametric context. Finally, a Reduced Order Time Spectral Method (ROTSM) is formulated in order to address the stability issues which involve the projection-based ROMs for fluid mechanics applications
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Hanada, Raíza Tamae Sarkis. "A noisy-channel based model to recognize words in eye typing systems." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-07112018-105429/.
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An important issue with eye-based typing iis the correct identification of both whrn the userselects a key and which key is selected. Traditional solutions are based on predefined gaze fixation time, known as dwell-time methods. In an attempt to improve accuracy long dwell times are adopted, which un turn lead to fatigue and longer response limes. These problems motivate the proposal of methods free of dwell-time, or with very short ones, which rely on more robust recognition techniques to reduce the uncertainty about user\'s actions. These techniques are specially important when the users have disabilities which affect their eye movements or use inexpensive eye trackers. An approach to deal with the recognition problem is to treat it as a spelling correction task. An usual strategy for spelling correction is to model the problem as the transmission of a word through a noisy-channel, such that it is necessary to determine which known word of a lexicon is the received string. A feasible application of this method requires the reduction of the set of candidate words by choosing only the ones that can be transformed into the imput by applying up to k character edit operations. This idea works well on traditional typing because the number of errors per word is very small. However, this is not the case for eye-based typing systems, which are much noiser. In such a scenario, spelling correction strategies do not scale well as they grow exponentially with k and the lexicon size. Moreover, the error distribution in eye typing is different, with much more insertion errors due to specific sources, of noise such as the eye tracker device, particular user behaviors, and intrinsic chracteeristics of eye movements. Also, the lack of a large corpus of errors makes it hard to adopt probabilistic approaches based on information extracted from real world data. To address all these problems, we propose an effective recognition approach by combining estimates extracted from general error corpora with domain-specific knowledge about eye-based input. The technique is ablçe to calculate edit disyances effectively by using a Mor-Fraenkel index, searchable using a minimun prfect hashing. The method allows the early processing of most promising candidates, such that fast pruned searches present negligible loss in word ranking quality. We also propose a linear heuristic for estimating edit-based distances which take advantage of information already provided by the index. Finally, we extend our recognition model to include the variability of the eye movements as source of errors, provide a comprehensive study about the importance of the noise model when combined with a language model and determine how it affects the user behaviour while she is typing. As result, we obtain a method very effective on the task of recognizing words and fast enough to be use in real eye typing systems. In a transcription experiment with 8 users, they archived 17.46 words per minute using proposed model, a gain of 11.3% over a state-of-the-art eye-typing system. The method was particularly userful in more noisier situations, such as the first use sessions. Despite significant gains in typing speed and word recognition ability, we were not able to find statistically significant differences on the participants\' perception about their expeience with both methods. This indicates that an improved suggestion ranking may not be clearly perceptible by the users even when it enhances their performance.Um problema importante em sistemas de digitação com os olhos é a correta identificação tanto de quando uma letra é selecionada como de qual letra foi selecionada pelo usuário. As soluções tradicionais para este problema são baseadas na verificação de quanto tempo o olho permanece retido em um alvo. Se ele fica por um certo limite de tempo, a seleção é reconhecida. Métodos em que usam esta ideia são conhecidos como baseados em tempo de retenção (dwell time). É comum que tais métodos, com intuito de melhorar a precisão, adotem tempos de retenção alto. Isso, por outro lado, leva à fadiga e tempos de resposta altos. Estes problemas motivaram a proposta de métodos não baseados em tempos de retenção reduzidos, que dependem de técnicas mais robustas de reconhecimento para inferir as ações dos usuários. Tais estratégias são particularmente mais importantes quando o usuário tem desabilidades que afetam o movimento dos olhos ou usam dispositivos de rastreamento ocular (eye-trackers) muito baratos e, portanto, imprecisos. Uma forma de lidar com o problema de reconhecimento das ações dos usuários é tratá-lo como correção ortográfica. Métodos comuns para correção ortográfica consistem em modelá-lo como a transmissão de uma palavra através de um canal de ruído, tal que é necessário determinar que palavra de um dicionário corresponde à string recebida. Para que a aplicação deste método seja viável, o conjunto de palavras candidatas é reduzido somente àquelas que podem ser transformadas na string de entrada pela aplicação de até k operações de edição de carácter. Esta ideia funciona bem em digitação tradicional porque o número de erros por palavra é pequeno. Contudo, este não é o caso de digitação com os olhos, onde há muito mais ruído. Em tal cenário, técnicas de correção de erros ortográficos não escalam pois seu custo cresce exponencialmente com k e o tamanho do dicionário. Além disso, a distribuição de erros neste cenário é diferente, com muito mais inserções incorretas devido a fontes específicas de ruído como o dispositivo de rastreamento ocular, certos comportamentos dos usuários e características intrínsecas dos movimentos dos olhos. O uso de técnicas probabilísticas baseadas na análise de logs de digitação também não é uma alternativa uma vez que não há corpora de dados grande o suficiente para tanto. Para lidar com todos estes problemas, propomos um método efetivo de reconhecimento que combina estimativas de corpus de erros gerais com conhecimento específico sobre fontes de erro encontradas em sistemas de digitação com os olhos. Nossa técnica é capaz de calcular distâncias de edição eficazmente usando um índice de Mor-Fraenkel em que buscas são feitas com auxílio de um hashing perfeito mínimo. O método possibilita o processamento ordenado de candidatos promissores, de forma que as operações de busca podem ser podadas sem que apresentem perda significativa na qualidade do ranking. Nós também propomos uma heurística linear para estimar distância de edição que tira proveito das informações já mantidas no índice, estendemos nosso modelo de reconhecimento para incluir erros vinculados à variabilidade decorrente dos movimentos oculares e fornecemos um estudo detalhado sobre a importância relativa dos modelos de ruído e de linguagem. Por fim, determinamos os efeitos do modelo no comportamento do usuário enquanto ele digita. Como resultado, obtivemos um método de reconhecimento muito eficaz e rápido o suficiente para ser usado em um sistema real. Em uma tarefa de transcrição com 8 usuários, eles alcançaram velocidade de 17.46 palavras por minuto usando o nosso modelo, o que corresponde a um ganho de 11,3% sobre um método do estado da arte. Nosso método se mostrou mais particularmente útil em situação onde há mais ruído, tal como a primeira sessão de uso. Apesar dos ganhos claros de velocidade de digitação, não encontramos diferenças estatisticamente significativas na percepção dos usuários sobre sua experiência com os dois métodos. Isto indica que uma melhoria no ranking de sugestões pode não ser claramente perceptível pelos usuários mesmo quanto ela afeta positivamente os seus desempenhos.
Books on the topic "Models of rupture (MOR)"
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Schjerfbeck, Helene. Helene Schjerfbeck: Min mor, hemma. Skärhamn, Sverige: Nordiska akvarellmuseet, 2000.
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Dalguer, Luis A., Yoshimitsu Fukushima, Kojiro Irikura, and Changjiang Wu, eds. Best Practices in Physics-based Fault Rupture Models for Seismic Hazard Assessment of Nuclear Installations. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-72709-7.
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The theory of critical distances: A new perspective in fracture mechanics. Amsterdam: Elsevier, 2007.
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service), SpringerLink (Online, ed. Atomistic Modeling of Materials Failure. Boston, MA: Springer Science+Business Media, LLC, 2008.
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U. S Forest U.S Forest Service and Department of Agriculture, United States. Improved Models for Predicting the Modulus of Rupture of Lumber under Third Point Loading. Independently Published, 2022.
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Wu, Changjiang, Kojiro Irikura, Luis A. Dalguer, and Yoshimitsu Fukushima. Best Practices in Physics-based Fault Rupture Models for Seismic Hazard Assessment of Nuclear Installations. Birkhäuser, 2017.
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Sui, Yueh Chun. Dynamic simulation of a Westinghouse PWR four-loop plant during steam generator tube rupture event. 1985.
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8
López-Sendón, José, and Esteban López de Sá. Mechanical complications of myocardial infarction. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199687039.003.0045.
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Mechanical complications after an acute infarction include different forms of heart rupture, including free wall rupture, interventricular septal rupture, and papillary muscle rupture. Its incidence decreased dramatically with the widespread use of reperfusion therapies but may occur in 2–3% of ST-elevation myocardial infarction patients, and mortality is very high if not properly diagnosed, as surgery is the only effective treatment. Echocardiography is the most important tool for diagnosis that should be suspected in patients with hypotension, heart failure, or recurrent chest pain. Awareness and well-established protocols are crucial for an early diagnosis. Modern imaging techniques permit a more reliable and direct identification of left ventricular free wall rupture, which is almost impossible to identify with conventional echocardiography. Mitral regurgitation, secondary to papillary muscle ischaemia or necrosis or left ventricular dilatation and remodelling, without papillary muscle rupture, is frequent after myocardial infarction and is considered as an independent risk factor for outcomes. Revascularization to control ischaemia and surgical repair should be considered in all patients with severe or symptomatic mitral regurgitation in the absence of severe left ventricular dysfunction. Other mechanical complications include true aneurysms and thrombus formation in the left ventricle. Again, these complications have decreased with the use of early reperfusion therapies and, for thrombus formation, with aggressive antithrombotic treatment. In a single large randomized trial (STICH), surgical remodelling of the left ventricle failed to demonstrate a significant improvement in outcomes, although it still may be an option in selected patients.
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López-Sendón, José, and Esteban López de Sá. Mechanical complications of myocardial infarction. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199687039.003.0045_update_001.
Full textAbstract:
Mechanical complications after an acute infarction include different forms of heart rupture, including free wall rupture, interventricular septal rupture, and papillary muscle rupture. Its incidence decreased dramatically with the widespread use of reperfusion therapies but may occur in 2–3% of ST-elevation myocardial infarction patients, and mortality is very high if not properly diagnosed, as surgery is the only effective treatment. Echocardiography is the most important tool for diagnosis that should be suspected in patients with hypotension, heart failure, or recurrent chest pain. Awareness and well-established protocols are crucial for an early diagnosis. Modern imaging techniques permit a more reliable and direct identification of left ventricular free wall rupture, which is almost impossible to identify with conventional echocardiography. Mitral regurgitation, secondary to papillary muscle ischaemia or necrosis or left ventricular dilatation and remodelling, without papillary muscle rupture, is frequent after myocardial infarction and is considered as an independent risk factor for outcomes. Revascularization to control ischaemia and surgical repair should be considered in all patients with severe or symptomatic mitral regurgitation in the absence of severe left ventricular dysfunction. Other mechanical complications include true aneurysms and thrombus formation in the left ventricle. Again, these complications have decreased with the use of early reperfusion therapies and, for thrombus formation, with aggressive antithrombotic treatment. In a single large randomized trial (STICH), surgical remodelling of the left ventricle failed to demonstrate a significant improvement in outcomes, although it still may be an option in selected patients.
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López-Sendón, José, and Esteban López de Sá. Mechanical complications of myocardial infarction. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199687039.003.0045_update_002.
Full textAbstract:
Mechanical complications after an acute infarction include different forms of heart rupture, including free wall rupture, interventricular septal rupture, and papillary muscle rupture. Its incidence decreased dramatically with the widespread use of reperfusion therapies but may occur in 2–3% of ST-elevation myocardial infarction patients, and mortality is very high if not properly diagnosed, as surgery is the only effective treatment. Echocardiography is the most important tool for diagnosis that should be suspected in patients with hypotension, heart failure, or recurrent chest pain. Awareness and well-established protocols are crucial for an early diagnosis. Modern imaging techniques permit a more reliable and direct identification of left ventricular free wall rupture, which is almost impossible to identify with conventional echocardiography. Mitral regurgitation, secondary to papillary muscle ischaemia or necrosis or left ventricular dilatation and remodelling, without papillary muscle rupture, is frequent after myocardial infarction and is considered as an independent risk factor for outcomes. Revascularization to control ischaemia and surgical repair should be considered in all patients with severe or symptomatic mitral regurgitation in the absence of severe left ventricular dysfunction. Other mechanical complications include true aneurysms and thrombus formation in the left ventricle. Again, these complications have decreased with the use of early reperfusion therapies and, for thrombus formation, with aggressive antithrombotic treatment. In a single large randomized trial (STICH), surgical remodelling of the left ventricle failed to demonstrate a significant improvement in outcomes, although it still may be an option in selected patients.
Book chapters on the topic "Models of rupture (MOR)"
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Gooch, Jan W. "Modulus of Rupture (MOR)." In Encyclopedic Dictionary of Polymers, 467. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_7592.
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Sornette, Didier. "Rupture Models." In Critical Phenomena in Natural Sciences, 257–84. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-04174-1_13.
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Sornette, D., A. Gilabert, and C. Vanneste. "Rupture in Random Media." In Random Fluctuations and Pattern Growth: Experiments and Models, 161–69. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-2653-0_28.
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Hemmer, P. C., A. Hansen, and S. Pradhan. "Rupture Processes in Fibre Bundle Models." In Modelling Critical and Catastrophic Phenomena in Geoscience, 27–55. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/3-540-35375-5_2.
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Niemann, Annika, Bernhard Preim, Oliver Beuing, and Sylvia Saalfeld. "Predicting Aneurysm Rupture with Deep Learning on 3D Models." In Informatik aktuell, 315–20. Wiesbaden: Springer Fachmedien Wiesbaden, 2022. http://dx.doi.org/10.1007/978-3-658-36932-3_65.
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Gafurov, Ulmas. "Molecular Model of Rupture of a Macromolecular Chain of a Loaded Oriented Crystalline Polymer." In Continuum Models and Discrete Systems, 223–29. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2316-3_35.
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Gillespie, Charles G. "Models of Democratic Transition in South America: Negotiated Reform versus Democratic Rupture." In Democratic Transition and Consolidation in Southern Europe, Latin America and Southeast Asia, 45–72. London: Palgrave Macmillan UK, 1990. http://dx.doi.org/10.1007/978-1-349-11412-2_3.
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Benner, Mats, Jonathan Grant, and Mary O’Kane. "Higher Education in Australia." In Crisis Response in Higher Education, 51–63. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97837-2_4.
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AbstractThis chapter outlines the evolution of universities in Australia. The chapter shows how Australian universities have been shaped in the interplay between academic, political and economic forces, and how the model of university governance has exposed them to vulnerabilities that ensue in periods of rapid ruptures in the surrounding society, especially when the globalisation of higher education is in peril. The chapter pays particular attention to the responses that have unfolded to the COVID-19 pandemic but also more generally to how universities have balanced the orientation to global templates with that of societal expectations.
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Benner, Mats, Jonathan Grant, and Mary O’Kane. "Higher Education in Australia." In Crisis Response in Higher Education, 51–63. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97837-2_4.
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AbstractThis chapter outlines the evolution of universities in Australia. The chapter shows how Australian universities have been shaped in the interplay between academic, political and economic forces, and how the model of university governance has exposed them to vulnerabilities that ensue in periods of rapid ruptures in the surrounding society, especially when the globalisation of higher education is in peril. The chapter pays particular attention to the responses that have unfolded to the COVID-19 pandemic but also more generally to how universities have balanced the orientation to global templates with that of societal expectations.
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Benner, Mats, Jonathan Grant, and Mary O’Kane. "Higher Education in Sweden: Unitary and Diversified Under State Authority." In Crisis Response in Higher Education, 41–50. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97837-2_3.
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AbstractThis chapter outlines the evolution of universities in Sweden. The chapter shows how Swedish universities have been shaped in the interplay between academic, political and economic forces and taken a specific form as an extension of political ambition, and how that model of university governance has exposed Swedish universities to both opportunities and vulnerabilities that ensue in periods of rapid ruptures. The chapter pays particular attention to the responses that have unfolded to the COVID-19 pandemic but also more generally to how universities in Sweden have balanced the orientation to global templates with that of political expectations.
Conference papers on the topic "Models of rupture (MOR)"
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Vengrenyuk, Yuliya, Luis Cardoso Landa, Stéphane Carlier, Shmuel Einav, and Sheldon Weinbaum. "Vulnerable Plaque Rupture Due to Stress Concentration Around Microcalcifications in the Thin Fibrous Cap." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176283.
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More than half of the 500,000 coronary artery disease deaths every year are due to the sudden rupture of vulnerable plaque. Several pathological studies of ruptured plaques have provided morphological descriptions of the high-risk, or vulnerable, coronary plaque that is prone to rupture or erosion as a positively remodeled lesion rich in vasa-vasorum, containing a lipid-rich core with an overlying thin fibrous cap infiltrated by macrophages. Virmani et al. [1] described thin-cap fibroatheroma with a large necrotic core and a fibrous cap < 65 μm as a more specific precursor of plaque rupture due to tissue stress. Despite the above observations, the mechanism of vulnerable plaque rupture has remained a mystery since ruptures often occur in regions where computational finite element (FEM) and fluid structure interaction (FSI) models do not predict maximal stress. Forty percent of ruptures occur in the central part of the cap rather than regions of high curvature at the shoulders of the lipid core where FEM models predict maximum tissue stresses [2]. Similarly, the latest study by Tang et al. [3] predicts that maximal stress often appears at healthy parts of the vessel where the vessel wall is thinner than the wall on the diseased plaque side or where vessel wall curvature is large.
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Fleming, Karl N., and Bengt O. Y. Lydell. "Use of Markov Piping Reliability Models to Evaluate Time Dependent Frequencies of Loss of Coolant Accidents." In 12th International Conference on Nuclear Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/icone12-49172.
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Markov model theory has been applied to develop a method to evaluate the influence of alternate strategies for in-service inspection and leak detection on the frequency of leaks and ruptures in nuclear power plant piping systems [1–4]. This approach to quantification of pipe rupture frequency was originally based on a Bayes’ uncertainty analysis approach to derive piping system failure rates from a combination of service experience data and some simple reliability models [5–7]. More recently the Markov model approach has been used in conjunction with probabilistic fracture mechanics methods in the study of flow accelerated corrosion [8]. One interesting property of the Markov model is its capability to evaluate time dependent rupture frequencies via the model hazard rate. In this paper this time dependent modeling capability is used to investigate the age related and time dependent frequencies of loss of coolant accident (LOCA) initiating event frequencies. A case is presented that plant age dependent LOCA frequencies should be used in lieu of other metrics commonly used in probabilistic risk assessments and in risk informed inservice inspection evaluations. Such more commonly used metrics include the assumed constant failure rate method and the lifetime average rupture probability. Both of these methods are shown to provide optimistic estimates of LOCA frequencies for plants in the latter part of their design lifetimes, which most operating plants are approaching.
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Zhao, Aihong, Ian Owens Pericevic, Kennerly Digges, Cing-Dao Kan, Moji Moatamedi, and Jeffrey S. Augenstein. "FE Modeling of the Orthotropic and Three-Layered Human Thoracic Aorta." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93573.
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The human aorta consists of three layers: intima, media and adventitia from the inner to outer layer. Since aortic rupture of victims in vehicle crashes frequently occurs in the intima and the media, latent aortic injuries are difficult to detect at the crash scene or in the emergency room. It is necessary to develop a multi-layer aorta finite element (FE) model to identify and describe the potential mechanisms of injury in various impact modes. In this paper, a novel three-layer FE aortic model was created to study aortic ruptures under impact loading. The orthotropic material model [1] has been implemented into a user-defined material subroutine in the commercial dynamic finite element software LS-DYNA version 970 [2], which was adopted in the aorta FE model. The Arbitrary-Lagrangian Eulerian (ALE) approach was adopted to simulate the interaction between the fluid (blood) and the structure (aorta). Single element verifications for the user-defined subroutine were performed. The mechanical behaviors of aortic tissues under impact loading were simulated by the aorta FE model. The models successfully predicted the rupture of the layers separately. The results provide a basis for a more in-depth investigation of blunt traumatic aortic rupture (BTAR) in vehicle crashes.
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Heasler, Patrick G., Scott E. Sanborn, Steven R. Doctor, and Michael T. Anderson. "The Treatment of ISI Uncertainty in Extremely Low Probability of Rupture." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57975.
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The U.S. Nuclear Regulatory Commission (NRC) in cooperation with the nuclear industry is constructing an improved probabilistic fracture model for piping systems that in the past have not been susceptible to known degradation processes that could lead to pipe rupture. Recent operating experience with primary water stress corrosion cracking (PWSCC) has challenged this prior position of leak-before-break and which has now become known as “extremely Low Probability of Rupture” (xLPR). This paper focuses on the xLPR model’s treatment of uncertainty for in-service inspection. In the xLPR model, uncertainty is classified as either aleatory or epistemic, and both types of uncertainty are described with probability distributions. Earlier PFM models included aleatory, but ignored epistemic, uncertainty, or attempted to deal with epistemic uncertainty by use of conservative bounds. Thus, inclusion of both types of uncertainty in xLPR should produce more realistic results than the earlier models. This work shows that by including epistemic uncertainty in the xLPR ISI module, there can be a significant effect on rupture probability; however, this depends upon the specific scenarios being studied. Some simple scenarios are presented to illustrate those where there is no effect and those having a significant effect on the probability of rupture.
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Vengrenyuk, Yuliya, Theodore J. Kaplan, Luis Cardoso, Gwendalyn J. Randolph, and Sheldon Weinbaum. "Biomechanical Modeling of Atherosclerotic Lesions in ApoE Deficient Mice." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206571.
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Cardiovascular disease remains the principal killer in the western world despite major advances in treatment of its patients [1]. It is generally accepted that sudden rupture of vulnerable plaque followed by thrombus formation underlies most cases of myocardial infarction and is responsible for more than a half of 500,000 coronary heart disease deaths every year. Although histopathological analysis of postmortem specimens have provided important data on histological features of ruptured human plaques, there is an urgent need for good representative animal models of plaque rupture. Over the last decade and a half, genetically engineered mice have been widely used to study the pathogenesis and potential treatment of atherosclerotic lesions, as well as genetic, hormonal and environmental influences on development of atherosclerosis. Though many of the features of plaque development and progression that occur in human plaques are similarly observed in murine plaques, these mouse models have long been regarded as poor models to study plaque rupture because the aortic sinus lesions seldom show any signs of fibrous cap disruption. Several recent studies reported potentially unstable atherosclerotic lesions in older apoE-deficient mice in another anatomic site, the proximal part of the brachiocephalic artery (BCA) [2, 3]. The unusual stability of aortic lesions compared to the BCA lesions in ApoE knockout mice is an unexplained paradox in developing a mouse model of plaque rupture. In this paper, we use histology based finite element analysis to evaluate peak circumferential stresses in aortic and BCA lesions from high fat fed ApoE KO mice.
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Washington, Christopher B., Judy Shum, Satish C. Muluk, and Ender A. Finol. "Abdominal Aortic Aneurysm Growth: The Association of Aortic Wall Mechanics and Geometry." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53977.
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In an effort to prevent rupture, patients with known AAA undergo periodic abdominal ultrasound or CT scan surveillance. When the aneurysm grows to a diameter of 5.0–5.5 cm or is shown to expand at a rate greater than 1 cm/yr, elective operative repair is undertaken. While this strategy certainly prevents a number of potentially catastrophic ruptures, AAA rupture can occur at sizes less than 5 cm. From a biomechanical standpoint, aneurysm rupture occurs when wall stress exceeds wall strength. By using non-invasive techniques, such as finite element analysis (FEA), wall stress can be estimated for patient specific AAA models, which can perhaps more carefully predict the rupture potential of a given aneurysm, regardless of size. FEA is a computational method that can be used to evaluate complicated structures such as aneurysms. To this end, it was reported earlier that AAA peak wall stress provides a better assessment of rupture risk than the commonly used maximum diameter criterion [1]. What has yet to be examined, however, is the relationship between wall stress and AAA geometry during aneurysm growth. Such finding has the potential for providing individualized predictions of AAA rupture potential during patient surveillance. The purpose of this study is to estimate peak wall stress for an AAA under surveillance and evaluate its potential correlation with geometric features characteristic of the aneurysm’s morphology.
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Haque, Mohammad Shafinul, and Calvin M. Stewart. "Modeling the Creep Deformation, Damage, and Rupture of Hastelloy X Using MPC Omega, Theta, and Sin-Hyperbolic Models." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63029.
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Combined cycle power plants components such as steam pipe work, pressure vessels, boilers, heat exchangers, and gas turbine disks, etc. are exposed to elevated temperature and pressure operation conditions for longer durations. Components may fail within the elastic limit due to a time dependent deformation and damage mechanism called creep. Creep prediction models are used to determine the state of these components and to schedule optimum inspection, maintenance, and replacement intervals. In this study, the deformation, damage, and life of Hastelloy X is characterized using three recently developed models; the Omega, Theta projection, and Sin-hyperbolic models. An analysis is performed to compare the models in terms of accuracy, assumptions, constant identification techniques, flexibility in use, and limitations. The influence that final creep strain has on Theta and Omega model is discussed. Sixteen tests were performed at four different configurations of stress (2.1–36.5 ksi) and temperature (1200–1800°F). In the experimental data, Hastelloy X does not exhibit the primary stage. In this study, the secondary and tertiary creep stages are modeled. Creep deformation and rupture life data is used to optimize the constants for the three models. Predictions using these models are compared with experimental data. It is found that the novel Sin-hyperbolic model better fits the experimental data, and is easier to apply. The Omega model predicts longer life than the Sinh and the Theta Projection model. The rupture life prediction of the Theta projection model is the worst due to dependence on the critical creep strain rate. It is observed that the Hastelloy X final creep strain depends on stress and temperature; this leads to a less accurate critical creep strain rate prediction resulting in inaccurate rupture life predictions for the Theta projection model. The analytical damage of the Omega model exhibits a linear evolution with time while the Sinh model show a more realistic elliptical creep damage evolution with time. A process to determine the constants of all the models is clearly described. The dependence of the trajectory of the creep curves with respect to the constants is discussed in detail. An analytical derivation of each model is provided. Predictions of these three models show that the Sinh model produces a better creep deformation curve by normalizing the experimental creep strain rate data. It is found that overall the Sinh model offers more flexibility, prediction accuracy, and is easier to apply.
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Ramirez, Christopher, Mohammad Shafinul Haque, and Calvin Maurice Stewart. "Guidelines to the Assessment of Creep Rupture Reliability for 316SS Using the Larson-Miller Time-Temperature Parameter Model." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65816.
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It is common practice to perform accelerated creep testing (ACT) using time-temperature parameter (TTP) models. The TTP models are calibrated to creep-rupture data at high temperature and/or stress and extrapolate to lower temperature and/or stress where data is not available. The long-term creep rupture behavior (at low temperature and stress) is often not available due to the quantity, duration, and cost of testing. A limited scope of creep-rupture data is often analyzed using the TTP models. When conducting long-term extrapolation, statistical uncertainty becomes an issue. The ability of the TTP models to accurately predict creep-rupture at long life is often limited and the inherent material properties can dramatically influence creep-rupture life. Unfortunately, there is no consensus on the statistic for assessing the quality of TTP extrapolation. This study demonstrates methodology to assessing the uncertainty in creep rupture predictions for 316SS using the Larson Miller parameter. Over 2,000 creep-rupture data points are collected and digitized from the NIMS, ASM, MAPTIS, and ORNL databases; metadata such as the material’s form, thermomechanical processing, and chemical composition are recorded. Statistical uncertainty is measured using the “Z parameter”, which describes the deviation of creep-rupture data to a TTP model. The ability of the TTP models to extrapolate to long life is analyzed via exclusion of data. This is accomplished by: excluding 50% of the data, and by excluding the longest 10% of the data. It is shown that culling data in any way produces more conservative creep rupture predictions. The spread of the dataset will also affect the width of the reliability bands.
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Cano, Jaime A., and Calvin M. Stewart. "Application of the Wilshire Stress-Rupture and Minimum-Creep-Strain-Rate Prediction Models for Alloy P91 in Tube, Plate and Pipe Form." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90625.
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Abstract There exists a challenge in predicting the long-term creep of materials (3 105 hours) where 11+ years of continuous testing is required to physically collect creep data. As an alternative to physical testing, constitutive models are calibrated to short-term data (< 104 hours) and employed to extrapolate the long-term creep behavior. The Wilshire model was introduced to predict the stress-rupture and minimum-creep-strain-rate behavior of materials and the model is well-accepted due to the explicit description of stress- and temperature-dependence allowing predictions across isotherms and stress levels. There is an ongoing effort to determine how alloy form affects the long-term creep predictions of the Wilshire model. In this study, stress-rupture and minimum-creep-strain-rate predictions are generated for alloy P91 in tube, plate, and pipe form. Data is gathered from the National Institute of Materials Science (NIMS) material database for alloy P91 at multiple isotherms. Following the establish calibration method for the Wilshire model, post-audit validation is performed using short-term data from NIMS to vet the extrapolations accuracy of each form at different isotherms. The Wilshire model demonstrates successful extrapolative techniques for the stress-rupture and minimum-creep-strain-rate of tube, plate, and pipe forms across multiple isotherms. Overall the form with the highest extrapolative accuracy for both stress-rupture and minimum-creep-strain-rate is the plate and the lowest one is the pipe. Stress-rupture design maps are provided where stress and temperature are axes and rupture-time is in contour. The design maps can be applied to: (a) given the boundary conditions, determine the design life (b) given the design life, determine the acceptable range of a boundary conditions. The latter is more useful in turbomachinery design.
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Csontos, Aladar, and Craig Harrington. "Development of a Probabilistic Pipe Rupture Assessment Code." In ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-26158.
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Appendix A, General Design Criteria (GDC) 4, of 10 CFR Part 50 states, in part, that the dynamic effects associated with postulated reactor coolant system pipe ruptures may be excluded from the design basis when analyses reviewed and approved by NRC demonstrate that the probability of fluid system piping rupture is extremely low under conditions consistent with the design basis. Licensees have typically demonstrated compliance with this probabilistic criterion through deterministic analyses that do not accurately simulate typical piping degradation. Given recent advances in probabilistic methodologies, the NRC staff and industry believe that performing a probabilistic analysis of primary system piping that fully addresses and quantifies uncertainties and directly demonstrates compliance with GDC 4 is more appropriate. NRC and industry expect that a robust probabilistic software tool, developed cooperatively, will facilitate meeting this goal; will improve licensing, regulatory decision making, and design; and will be mutually beneficial. Based on the terminology of GDC 4, this project is titled Extremely Low Probability of Rupture (xLPR). Development of the xLPR methodology and the corresponding software tool will involve many challenging technical decisions, modeling judgments, and sensitivity analyses. The purpose of the xLPR project is to develop a probabilistic assessment tool that can be used to demonstrate direct compliance with the requirements of 10 CFR 50 Appendix A GDC 4. The xLPR software tool will model active degradation mechanisms, such as primary water stress corrosion cracking, and the associated mitigation activities. The tool will be comprehensive with respect to known challenges, vetted with respect to scientific adequacy of models and inputs, flexible enough to permit analysis of a variety of in-service situations, and adaptable to accommodate evolving and improving knowledge. Successful execution of the xLPR project will involve a complex and diverse array of technical specialties and will require a well-organized and structured team of experts. This paper summarizes the objectives, organizational structure, and program plan of the collaborative NRC / Industry xLPR Project to develop a robust, flexible, probabilistic piping rupture assessment code. While the listed authors are individually responsible within their respective organizations for this project, the project organization includes a management team representing the xLPR Project task group structure. Individual members of this team will be listed in the paper along with their individual roles and contributions within the project. Companion papers from three of the four technical Task Groups of the xLPR Program (Computational, Modeling, and Inputs) provide substantial additional information detailing the technical approach and direction of this project.
Reports on the topic "Models of rupture (MOR)"
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P. Macheret. COMPARISON OF CLADDING CREEP RUPTURE MODELS. Office of Scientific and Technical Information (OSTI), June 2000. http://dx.doi.org/10.2172/886036.
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Pitarka, A. Testing Dynamic Earthquake Rupture Models Generated With Stochastic Stress Drop. Office of Scientific and Technical Information (OSTI), November 2018. http://dx.doi.org/10.2172/1490953.
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Plourde, A. P., and J. F. Cassidy. Mapping tectonic stress at subduction zones with earthquake focal mechanisms: application to Cascadia, Japan, Nankai, Mexico, and northern Chile. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330943.
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Earthquake focal mechanisms have contributed substantially to our understanding of modern tectonic stress regimes, perhaps more than any other data source. Studies generally group focal mechanisms by epicentral location to examine variations in stress across a region. However, stress variations with depth have rarely been considered, either due to data limitations or because they were believed to be negligible. This study presents 3D grids of tectonic stress tensors using existing focal mechanism catalogs from several subduction zones, including Cascadia, Japan, Nankai, Mexico, and northern Chile. We bin data into 50 x 50 x 10 km cells (north, east, vertical), with 50% overlap in all three directions. This resulted in 181380 stress inversions, with 90% of these in Japan (including Nankai). To the best of our knowledge, this is the first examination of stress changes with depth in several of these regions. The resulting maps and cross-sections of stress can help distinguish locked and creeping segments of the plate interface. Similarly, by dividing the focal mechanism catalog in northern Japan into those before and those &gt;6 months after the 2011 Mw 9.1 Tohoku-Oki earthquake, we are able to produce detailed 3D maps of stress rotation, which is close to 90° near the areas of highest slip. These results could inform geodynamic rupture models of future megathrust earthquakes in order to more accurately estimate slip, shaking, and seismic hazard. Southern Cascadia and Nankai appear to have sharp stress discontinuities at ~20 km depth, and northern Cascadia may have a similar discontinuity at ~30 km depth. These stress boundaries may relate to rheological discontinuities in the forearc, and may help us unravel how forearc composition influences subduction zone behaviour and seismic hazard.
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Foxall, William. Heterogeneous slip and rupture models of the San Andreas fault zone based upon three-dimensional earthquake tomography. Office of Scientific and Technical Information (OSTI), November 1992. http://dx.doi.org/10.2172/10163876.
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Ely, Geoffrey P. Using Multi-scale Dynamic Rupture Models to Improve Ground Motion Estimates: ALCF-2 Early Science Program Technical Report. Office of Scientific and Technical Information (OSTI), October 2013. http://dx.doi.org/10.2172/1114107.
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Verrill, Steve P., Frank C. Owens, David E. Kretschmann, and Rubin Shmulsky. Statistical models for the distribution of modulus of elasticity and modulus of rupture in lumber with implications for reliability calculations. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, 2017. http://dx.doi.org/10.2737/fpl-rp-692.
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Shomer, Ilan, Ruth E. Stark, Victor Gaba, and James D. Batteas. Understanding the hardening syndrome of potato (Solanum tuberosum L.) tuber tissue to eliminate textural defects in fresh and fresh-peeled/cut products. United States Department of Agriculture, November 2002. http://dx.doi.org/10.32747/2002.7587238.bard.
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The project sought to understand factors and mechanisms involved in the hardening of potato tubers. This syndrome inhibits heat softening due to intercellular adhesion (ICA) strengthening, compromising the marketing of industrially processed potatoes, particularly fresh peeled-cut or frozen tubers. However, ICA strengthening occurs under conditions which are inconsistent with the current ideas that relate it to Ca-pectate following pectin methyl esterase (PME) activity or to formation of rhamnogalacturonan (RG)-II-borate. First, it was necessary to induce strengthening of the middle lamellar complex (MLX) and the ICA as a stress response in some plant parenchyma. As normally this syndrome does not occur uniformly enough to study it, we devised an efficient model in which ICA-strengthening is induced consistently under simulated stress by short-chain, linear, mono-carboxylic acid molecules (OAM), at 65 oC [appendix 1 (Shomer&Kaaber, 2006)]. This rapid strengthening was insufficient for allowing the involved agents assembly to be identifiable; but it enabled us to develop an efficient in vitro system on potato tuber parenchyma slices at 25 ºC for 7 days, whereas unified stress was reliably simulated by OAMs in all the tissue cells. Such consistent ICA-strengthening in vitro was found to be induced according to the unique physicochemical features of each OAM as related to its lipophilicity (Ko/w), pKa, protonated proportion, and carbon chain length by the following parameters: OAM dissociation constant (Kdiss), adsorption affinity constant (KA), number of adsorbed OAMs required for ICA response (cooperativity factor) and the water-induced ICA (ICAwater). Notably, ICA-strengthening is accompanied by cell sap leakage, reflecting cell membrane rupture. In vitro, stress simulation by OAMs at pH<pKa facilitated the consistent assembly of ICAstrengthening agents, which we were able to characterize for the first time at the molecular level within purified insoluble cell wall of ICA-strengthened tissue. (a) With solid-state NMR, we established the chemical structure and covalent binding to cell walls of suberin-like agents associated exclusively with ICA strengthening [appendix 3 (Yu et al., 2006)]; (b) Using proteomics, 8 isoforms of cell wall-bound patatin (a soluble vacuolar 42-kDa protein) were identified exclusively in ICA-strengthened tissue; (c) With light/electron microscopy, ultrastructural characterization, histochemistry and immunolabeling, we co-localized patatin and pectin in the primary cell wall and prominently in the MLX; (d) determination of cell wall composition (pectin, neutral sugars, Ca-pectate) yielded similar results in both controls and ICA-strengthened tissue, implicating factors other than PME activity, Ca2+ or borate ions; (e) X-ray powder diffraction experiments revealed that the cellulose crystallinity in the cell wall is masked by pectin and neutral sugars (mainly galactan), whereas heat or enzymatic pectin degradation exposed the crystalline cellulose structure. Thus, we found that exclusively in ICA-strengthened tissue, heat-resistant pectin is evident in the presence of patatin and suberinlike agents, where the cellulose crystallinity was more hidden than in fresh control tissue. Conclusions: Stress response ICA-strengthening is simulated consistently by OAMs at pH< pKa, although PME and formation of Ca-pectate and RG-II-borate are inhibited. By contrast, at pH>pKa and particularly at pH 7, ICA-strengthening is mostly inhibited, although PME activity and formation of Ca-pectate or RG-II-borate are known to be facilitated. We found that upon stress, vacuolar patatin is released with cell sap leakage, allowing the patatin to associate with the pectin in both the primary cell wall and the MLX. The stress response also includes formation of covalently bound suberin-like polyesters within the insoluble cell wall. The experiments validated the hypotheses, thus led to a novel picture of the structural and molecular alterations responsible for the textural behavior of potato tuber. These findings represent a breakthrough towards understanding of the hardening syndrome, laying the groundwork for potato-handling strategies that assure textural quality of industrially processed particularly in fresh peeled cut tubers, ready-to-prepare and frozen preserved products.