Academic literature on the topic 'Multi-scale limit'
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Journal articles on the topic "Multi-scale limit"
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Khoei, A. R., and M. Jahanshahi. "Multi-scale modeling of plastic deformations in nano-scale materials; Transition to plastic limit." International Journal for Numerical Methods in Engineering 109, no. 8 (November 29, 2016): 1180–216. http://dx.doi.org/10.1002/nme.5327.
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MINH, C. HA, FR BOUSSU, A. IMAD, T. KANIT, and D. CRÉPIN. "MULTI-SCALE MODEL TO PREDICT THE BALLISTIC IMPACT BEHAVIOR OF MULTI-LAYER PLAIN-WOVEN FABRICS." International Journal of Computational Methods 11, no. 03 (June 2014): 1343011. http://dx.doi.org/10.1142/s0219876213430111.
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This paper presents a multi-scale model that can predict the ballistic impact behavior of multi-layer plain-woven fabrics using the finite element method (FEM). Multi-layer fabrics of 30.5 × 30.5 cm, woven by high performance yarns Kevlar® 29 3000 denier, are impacted by a 0.3 fragment simulating projectile (FSP). Using a multi-scale approach, behavior of multi-layer fabrics subjected to different impact velocities is numerically analyzed. Ballistic limit of the fabric can also be predicted. The multi-scale model shows an effective gain of computation time in comparison with current mesoscopic ones. Computational results show a good agreement with experimental data.
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Jung, M., T. F. Illenseer, and W. J. Duschl. "Multi-scale simulations of black hole accretion in barred galaxies." Astronomy & Astrophysics 614 (June 2018): A105. http://dx.doi.org/10.1051/0004-6361/201731688.
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Due to the non-axisymmetric potential of the central bar, in addition to their characteristic arms and bar, barred spiral galaxies form a variety of structures within the thin gas disk, such as nuclear rings, inner spirals, and dust lanes. These structures in the inner kiloparsec are extremely important in order to explain and understand the rate of black hole feeding. The aim of this work is to investigate the influence of stellar bars in spiral galaxies on the thin self-gravitating gas disk. We focus on the accretion of gas onto the central supermassive black hole and its time-dependent evolution. We conducted multi-scale simulations simultaneously resolving the galactic disk and the accretion disk around the central black hole. In all the simulations we varied the initial gas disk mass. As an additional parameter we chose either the gas temperature for isothermal simulations or the cooling timescale for non-isothermal simulations. Accretion was either driven by a gravitationally unstable or clumpy accretion disk or by energy dissipation in strong shocks. Most of the simulations show a strong dependence of the accretion rate at the outer boundary of the central accretion disk (r < 300 pc) on the gas flow at kiloparsec scales. The final black hole masses reach up to ~109 M⊙ after 1.6 Gyr. Our models show the expected influence of the Eddington limit and a decline in growth rate at the corresponding sub-Eddington limit.
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Kyoya, Takashi, Kenjiro Terada, and Toshikazu Kawamoto. "Multi-scale limit load analysis for discontinuous rock mass based on the homogenization method." International Journal for Numerical and Analytical Methods in Geomechanics 23, no. 10 (August 25, 1999): 995–1019. http://dx.doi.org/10.1002/(sici)1096-9853(19990825)23:10<995::aid-nag21>3.0.co;2-b.
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Cotter, C. J., G. A. Gottwald, and D. D. Holm. "Stochastic partial differential fluid equations as a diffusive limit of deterministic Lagrangian multi-time dynamics." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, no. 2205 (September 2017): 20170388. http://dx.doi.org/10.1098/rspa.2017.0388.
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In Holm (Holm 2015 Proc. R. Soc. A 471 , 20140963. ( doi:10.1098/rspa.2014.0963 )), stochastic fluid equations were derived by employing a variational principle with an assumed stochastic Lagrangian particle dynamics. Here we show that the same stochastic Lagrangian dynamics naturally arises in a multi-scale decomposition of the deterministic Lagrangian flow map into a slow large-scale mean and a rapidly fluctuating small-scale map. We employ homogenization theory to derive effective slow stochastic particle dynamics for the resolved mean part, thereby obtaining stochastic fluid partial equations in the Eulerian formulation. To justify the application of rigorous homogenization theory, we assume mildly chaotic fast small-scale dynamics, as well as a centring condition. The latter requires that the mean of the fluctuating deviations is small, when pulled back to the mean flow.
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Sun, Xiangkun, Changwei Zhou, Mohamed Ichchou, Jean-Pierre Lainé, and Abdel-Malek Zine. "Multi-Scale Homogenization of Transversal Waves in Periodic Composite Beams." International Journal of Applied Mechanics 09, no. 03 (April 2017): 1750039. http://dx.doi.org/10.1142/s1758825117500399.
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This paper deals with the deduction of new homogenized models for the flexural wave in bi-periodic beams. According to the homogenization theory, the long-wave assumption is used and the valid frequency range of homogenized models is limited to the first Bragg band gap. However, the classical homogenization method, whose idea is taking the component’s mean values as effective material properties, has limitations in mimicking the dispersive behavior and the real valid frequency range is far less than the limit. Thus, enriched homogenized models, derived by the multi-scale asymptotic homogenization method, are proposed to provide more accurate homogenization models with larger real valid frequency range. The new homogenized models are validated by investigating the dispersion relation in the infinite case and the frequency response function in the finite case. Wave finite element method (WFEM) are used to provide associated references. A parametric study is carried out in the infinite case while two different boundary conditions are considered in the finite case.
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Vulliez, Margot, Matthew A. Gleason, Aurélien Souto-Lebel, Yann Quinsat, Claire Lartigue, Steven P. Kordell, Adam C. Lemoine, and Christopher A. Brown. "Multi-scale Curvature Analysis and Correlations with the Fatigue Limit on Steel Surfaces after Milling." Procedia CIRP 13 (2014): 308–13. http://dx.doi.org/10.1016/j.procir.2014.04.052.
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Xiao, Liang, Yan Li, Huangqing Xiao, Zheren Zhang, and Zheng Xu. "Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems." Energies 11, no. 8 (August 13, 2018): 2102. http://dx.doi.org/10.3390/en11082102.
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A method for electromechanical modeling of line commutated converter (LCC)-modular multilevel converter (MMC)-based hybrid multi-terminal High Voltage Direct Current Transmission (HVDC) systems for large-scale power system transient stability study is proposed. Firstly, the general idea of modeling the LCC-MMC hybrid multi-terminal HVDC system is presented, then the AC-side and DC-side models of the LCC/MMC are established. Different from the conventional first-order DC-side model of the MMC, an improved second-order DC-side model of the MMC is established. Besides considering the firing angle limit of the LCC, a sequential power flow algorithm is proposed for the initialization of LCC-MMC hybrid multi-terminal HVDC system. Lastly, simulations of small scale and large scale power systems embedded with a three-terminal LCC-MMC hybrid HVDC system are performed on the electromechanical simulation platform PSS/E. It is demonstrated that if the firing angle limit is not considered, the accuracy of the power flow solutions will be greatly affected. Steady state calculation and dynamic simulation show that the developed LCC-MMC hybrid MTDC model is accurate enough for electromechanical transient stability studies of large-scale AC/DC system.
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Yang, Mao, Yu Cui, Dawei Huang, Xin Su, and Gang Wu. "Multi-time-scale coordinated optimal scheduling of integrated energy system considering frequency out-of-limit interval." International Journal of Electrical Power & Energy Systems 141 (October 2022): 108268. http://dx.doi.org/10.1016/j.ijepes.2022.108268.
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Hart, W. S., P. K. Maini, C. A. Yates, and R. N. Thompson. "A theoretical framework for transitioning from patient-level to population-scale epidemiological dynamics: influenza A as a case study." Journal of The Royal Society Interface 17, no. 166 (May 2020): 20200230. http://dx.doi.org/10.1098/rsif.2020.0230.
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Multi-scale epidemic forecasting models have been used to inform population-scale predictions with within-host models and/or infection data collected in longitudinal cohort studies. However, most multi-scale models are complex and require significant modelling expertise to run. We formulate an alternative multi-scale modelling framework using a compartmental model with multiple infected stages. In the large-compartment limit, our easy-to-use framework generates identical results compared to previous more complicated approaches. We apply our framework to the case study of influenza A in humans. By using a viral dynamics model to generate synthetic patient-level data, we explore the effects of limited and inaccurate patient data on the accuracy of population-scale forecasts. If infection data are collected daily, we find that a cohort of at least 40 patients is required for a mean population-scale forecasting error below 10%. Forecasting errors may be reduced by including more patients in future cohort studies or by increasing the frequency of observations for each patient. Our work, therefore, provides not only an accessible epidemiological modelling framework but also an insight into the data required for accurate forecasting using multi-scale models.
Dissertations / Theses on the topic "Multi-scale limit"
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Suberu, Bolaji A. "Multi-scale Composite Materials with Increased Design Limits." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377868507.
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Billon, Laure. "Génération et adaptation de maillage volume-couche limite dynamique pour les écoulements turbulents autour de géométries complexes." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM077/document.
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La simulation numérique des écoulements turbulents en aérodynamique est très complexe. Elle consiste en l'étude de l'interaction entre un fluide et un profilimmergé. On observe à la surface du profil une zone de vitesse ralentie, nommée couche limite. L'étude fine de la couche limite est primordiale pour la résolution précise de l'écoulement. Elle nécessite de ce fait un maillage particulièrement fin et structuré. Nous proposons une procédure automatique permettant de générer un maillage adapté pour la résolution précise de la couche limite en accord avec la théorie et les caractéristiques physiques de l'écoulement. De plus, afin de décrire l'écoulement turbulent dans toute sa complexité à moindres coûts, nous proposons de combiner le maillage couche limite à une méthode d’adaptation de maillage dynamique.A cet effet, nous avons utilisé une version avancée de l'adaptation de maillagesur l'erreur a posteriori basée sur les arêtes et développé une méthode permettant à la fois de conserver la structure et le raffinement dans la couche limite mais également de décrire précisément les recirculations et le sillage. La nouvelle méthode d'adaptation volume-couche limite a été validée sur des cas2D et 3D à géométries complexes. Les résultats mettent en relief le potentiel decette approche et ouvre des perspectives intéressantes pour l'adaptation de maillage en mécanique des fluidesNumerical simulation of turbulent aerodynamics flows remains challenging. Such fluid-structure interaction problem involves generally a thin layer close to the wall where the fluid is slow down, called boundary layer. This latter requires a carefull study of the boundary layer since it is crucial regarding the accuracyof the complete flow computation. Therefore, a fine and structured mesh is needed close to the wall. In this work, we propose a novel automatic procedure to build a correct boundary layer mesh according to the theory and the flow parameters. Moreover, in order to describe exactly the behaviour of the flow on the whole domain, the boundary layer mesh is combined with a dynamic mesh adaptation method.It follows an advanced version of the edge based mesh adaptation method. Combined together, they ensure a fine and structured mesh in the boundarylayer while all the flow vortices are accurately resolved. This new method, called boundary-volume mesh adaptation, has been validated on several 2D and 3Dtest cases with complex geometries. Results emphasises the capacity ofthe approach and offer opportunities of improvement for numerical fluid mechanics mesh adaptation
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Bonaventure, Julien. "Influence of random surface roughness on friction in elastohydrodynamic, mixed and boundary lubrication." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC038/document.
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La plupart des systèmes mécaniques contiennent des contacts lubrifiés (articulations, roulements, ...) qui sont soumis à des efforts importants. Dans ce travail expérimental, on s’intéresse à l’influence de la rugosité sur la friction dans les régimes de lubrification élastohydrodynamique (EHD), mixte, et limite dans des conditions représentatives des contacts dans un moteur de voiture. Les surfaces utilisées dans ce travail sont principalement des aciers usinés industriellement, revêtus ou non de Diamond-Like Carbon (DLC). La force de friction dans les régimes mixte et limite étant bien plus importante qu’en régime EHD, il est important de pouvoir prédire les transitions d’un régime à l’autre. Le problème est que la rugosité affecte significativement les vitesses de transition entre ces régimes, de telle manière qu’il est difficile de prédire le régime de fonctionnement d’un couple donné de surfaces. Les travaux expérimentaux s’attardant sur ce problème sont rares, et les tentatives théoriques d’inclure l’effet de rugosités aléatoires reposent sur des paramètres difficiles à mesurer à cause de leur grande dépendance vis-à-vis des conditions de filtrage, d’échantillonnage, et de leur non-stationnarité. à partir de nombreuses mesures topograhiques (interférométrie et AFM), une méthode assurant la représentativité des paramètres statistiques de rugosité est donc d’abord mise en œuvre pour caractériser des surfaces dont la rugosité va du nanomètre au micron. Des expériences de Stribeck sont ensuite menées avec ces surfaces afin de corréler leur signature morphologique à leur comportement en friction. La rhéologie sous pression de lubrifiants (poly-α oléfines) est mesurée dans un contact lisse en fonction de la pression et de la température, ce qui permet de prédire quantitativement la friction en régime élastohydrodynamique pour tout couple de surfaces, mais aussi de définir un critère non phénoménologique d’entrée en régime de lubrification mixte. à haute vitesse d’entraînement, la contrainte visqueuse décroît avec le taux de cisaillement ce qui est traditionnellement attribué à un échauffement du lubrifiant. On montre que les effets thermiques ne peuvent expliquer une telle chute et on l’explique par l’étalement du profil de pression dans le convergent, phénomène significatif quand l’épaisseur de lubrifiant devient de l’ordre d’un dixième de la taille du contact. Les résultats montrent que le produit de la viscosité dans le convergent avec la vitesse d’entraînement à la transition mixte-EHD suit une loi de puissance super-linéaire avec la rugosité, tous matériaux confondus, ce qui permet de prédire cette transition en fonction de la rugosité. La transition entre régimes mixte et limite est plus complexe et laisse apparaître un comportement clairement différent entre les contacts DLC/DLC et les contacts mettant en jeu au moins une surface d’acier. Pour les contacts DLC/DLC, la friction en régime limite correspond au cisaillement plastique du lubrifiant, ce qui explique que la rugosité n’affecte pas le frottement limite de ces contacts. Le frottement des contacts acier/acier et acier/DLC est plus important et présente deux évolutions monotones avec la rugosité composite du contact, que nous interprétons grâce à des expériences tribologiques à haut taux de glissement. Finalement, un modèle de portance mixte basé sur la théorie de Greenwood-Williamson est mis en œuvre et permet de reproduire avec une précision honorable les courbes de Stribeck obtenues expérimentalement. En particulier, ce modèle permet de déterminer les conditions d’échantillonnage optimales pour déterminer les propriétés des aspéritésMost mechanical systems include lubricated contacts submitted to important strengths. The present work deals with the influence of surface roughness on friction in the elastohydrodynamic (EHD), mixed and boundary lubrication regimes, with operating conditions that are typically those found in an internal combustion engine. Most of the surfaces used in the experiments are machined steel, with or with a Diamond-Like Carbon (DLC) coating. Given the friction in boundary and mixed lubrication being higher than in EHD lubrication, it is crucial to predict the transitions between these regimes. These strongly depend on surface roughness. There are very few experimental works that deal with this issue, and the theoretical attempts to include the influence of random surface roughness are based on roughness parameters that are difficult to measure because of their dependence towards the sampling conditions and their non-stationarity. Based on numerous topographical surveys (using interferometry and AFM), a method is implemented to ensure the representativeness of roughness statistical parameters in order to characterize a range of surface roughnesses within the interval [0.001 ; 1] μm. Then, these surfaces are rubbed against each other using Stribeck procedures in order to correlate their morphology to their friction behaviour. The high-pressure rheology of poly-α olefins is measured in smooth contacts with respect to the pressure and the temperature. This not only allows to quantify the friction force for any contact operating in EHD lubrication, but also to set a criterion to spot the onset of mixed lubrication. At high entrainment speed, the viscous shear stress vanishes, which is often attributed to shear heating. It is shown that thermal effects can not explain such a drop of friction for our own experiments. However, the widening of the pressure profile — which becomes significant when the film thickness becomes comparable to a tenth the contact length — is more likely to explain this behaviour. Our results show that the product of the inlet viscosity with the entrainment speed, spotted at the mixed-EHD transition, follows a super linear power law with the RMS roughness, whatever the materials involved, which allows to predict whether a contact operate in mixed lubrication or not. The transition from mixed to boundary lubrication reveals material and roughness-dependent with a clearly different behaviour between DLC/DLC contacts and contacts involving at least one steel body. Regarding the DLC/DLC contacts, the boundary friction is due to the plastic shearing of the lubricant, which explains why surface roughness has no influence on boundary friction for these contacts. With Steel/DLC and steel/steel contacts, the boundary friction presents two monotonous trends versus the composite RMS roughness. Eventually, a mixed bearing model based on the Greenwood-Willimason assumptions was implemented and allowed to reproduce quite closely the experimentally obtained Stribeck curves. This implementation indicates in particular the sampling conditions that are optimal to capture relevant asperity parameters
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Blackman, Karin. "Interactions multi-échelles entre la basse atmosphère et la canopée urbaine." Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0028.
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La couche limite urbaine est caractérisée par la présence de structures cohérentes complexes, telles que des structures de grande échelle à basse vitesse, et par des processus turbulents intermittents de balayage et d’éjection, responsables du transport de masse, de chaleur et de quantité de mouvement. Ces structures sont bien identifiées qualitativement mais leurs interactions avec les petites structures induites par la présence de la canopée urbaine sont encore mal connues. Afin d'étudier ces interactions, des écoulements de couche limite se développant sur des parois rugueuses sont étudiés en soufflerie. Le signal à petite échelle n'étant pas résolu temporellement, l'estimation stochastique linéaire est utilisée pour décomposer le champ de vitesse en grandes et petites échelles. On confirme que les structures à grande échelle dans la couche limite influencent les petites échelles proches de la rugosité à travers un mécanisme non linéaire similaire à une modulation d'amplitude. On montre également que la modification de la géométrie des éléments de rugosité entraîne une modification de cette interaction non linéaire dans la couche cisaillée. Le bilan complet de l'énergie cinétique turbulente (TKE), incluant la dissipation, est calculé à l'aide d'un modèle LE-PIV et démontre que les structures à petite échelle dans la couche de cisaillement sont importantes pour la production, le transport et la dissipation de l'énergie. Enfin, la décomposition triple du bilan de TKE confirme que la relation non linéaire qui existe entre les structures à grande échelle et les petites échelles proches de la rugosité est liée au transfert d'énergie entre ces structuresThe urban boundary layer consists of complex coherent structures, such as large-scale low momentum regions and intermittent turbulent sweeps and ejections, which are responsible for the transport of heat, momentum and pollution. Although these structures have been well identified, their quantitative relationship with the flow inside the canopy is still unknown. Wind tunnel modelling of flow over simplified rough terrain consisting of either three-dimensional or twodimensional roughness elements are able to reproduce these structures and are used to investigate the nonlinear relationship between large-scale momentum regions and small-scales induced by the presence of the roughness. As the temporally resolved small-scale signalis not available Linear Stochastic Estimation is used to decompose the flow into large and small-scales and confirm that the large-scale structures within the overlying boundary layer influence the small-scales close to the roughness through a non-linear mechanism similar to amplitude modulation. Changing terrain configuration from 3D to 2D roughness results in a modification of the non-linear relationship closer to the shear layer that develops near the top of the obstacles. The full turbulent kinetic energy (TKE) budget including dissipation is calculated using an LE-PIV model and demonstrates that small-scale structures within the shear layer are important to the production, transport and dissipation of energy. Finally, triple decomposition of theTKE budget confirms that the non-linear relationship that exists between large-scale momentum regions and small-scales close to the roughness is related to energy transfer between these structures
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Lin, Chia-Hsiang, and 林嘉祥. "Nighttime Image Dehazing Based on Improved Erosion Dark Channel and Multi-scale Clipping Limit Histogram Equalization." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/4xee4r.
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碩士國立臺灣科技大學
電機工程系
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Photographs taken at night time with haze often suffers from poor visibility and color distortion due to uneven local light sources. In this scenario, the common daytime dehazing algorithm results increased atmospheric light due to the influence of local light sources. Due to this, the result of the transmission is affected, resulting in excessive haze removal, noise amplification and artifacts introduction. Consequently, this thesis proposes a new night time dehazing algorithm by modifying the calculation method of atmospheric light and transmission used in the dark channel priors proposed by He[2]. First, the proposed erosion Gaussian-based dark channel is applied to suppress local light sources. Subsequently, a modified transmission calculation method is proposed which combines the erosion operator with the transmission. As the transmission is obtained, the refinement operation is performed. The multi-scale guided filter utilizing improved transmission is applied to the proposed multi-scale guided filters for refinement. Through this improved calculations, the unpleasant issues can be well controlled, including excessive dehazing, excessive darkness, artifacts and excessive amplification of noise. In addition to the above three improvements on the dehazing algorithm, the ICLAHE proposed by Guo[22] et al is also modified with multi-scale clipping limits to further improve the image quality. With the proposed Multi-scale clipping limit of ICLAHE, details can be obtained. As documented in the experimental results, the proposed method can yield superior performance towards nighttime dehazing effect and of less computational complexity in comparison against the state-of-the-art methods.
Book chapters on the topic "Multi-scale limit"
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Xu, Borui, Tong Zhang, and Weiguo Liu. "A Multi-scale Convolution and Gated Recurrent Unit Based Network for Limit Order Book Prediction." In Knowledge Science, Engineering and Management, 71–84. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-10983-6_6.
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Milenin, Alexey, Elena Velikoivanenko, Galina Rozynka, and Nina Pivtorak. "Multi-scale Finite-Element Model for Numerical Prediction of Subcritical Damage and Limit State of Fiber-Reinforced Composites and Structures." In Lecture Notes in Mechanical Engineering, 238–46. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-18487-1_24.
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Proelss, Alexander, and Robert C. Steenkamp. "Geoengineering: Methods, Associated Risks and International Liability." In Corporate Liability for Transboundary Environmental Harm, 419–503. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-13264-3_9.
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AbstractClimate change arguably constitutes one of the greatest risks to the long-term health of the world’s environment. In 2015, the Intergovernmental Panel on Climate Change (IPCC) highlighted that the Earth’s climate system has consistently been warming since the 1950s and that a “large fraction of anthropogenic climate change resulting from CO2 emissions is irreversible on a multi-century to millennial time scale, except in the case of a large net removal of CO2 from the atmosphere over a sustained period”. Initial responses to climate change revolved around States attempting to reduce, rather than remove, greenhouse gas emissions. However, as the global economy expands, greenhouse gas emissions have continued to rise and cooperative arrangements aimed at reducing emissions have had limited, if any, impact. If recent predictions are to be believed, the remaining “carbon budget” needed to prevent average global temperatures from increasing by more than 1.5 °C may be exhausted by 2030. Climate Analytics estimates that the current Nationally Determined Contributions (NDCs) made by States under the Paris Agreement indicate that average global temperatures will rise by 2.8 °C by 2100—almost double the stipulated efforts to limit the temperature increase to 1.5 °C above pre-industrial levels mentioned in Article 2(1)(a) of the Paris Agreement. The recent IPCC Special Report on 1.5 °C Global Warming concludes that without “increased and urgent mitigation ambition in the coming years, leading to a sharp decline in greenhouse gas emissions by 2030, global warming will [cause] irreversible loss of the most fragile ecosystems and crisis after crisis for the most vulnerable people and societies”.
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Pizzo, Alessandro. "Multi-scale Analysis in the Occupation Numbers of Particle States: An Application to Three-Modes Bogoliubov Hamiltonians." In Macroscopic Limits of Quantum Systems, 123–44. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-01602-9_6.
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Reid, Walter V., and Harold A. Mooney. "The Millennium Ecosystem Assessment: Testing the Limits of Interdisciplinary and Multi-scale Science." In Ecology, Economy and Society, 49–61. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-5675-8_4.
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Diestmann, Thomas, Nils Broedling, Benedict Götz, and Tobias Melz. "Surrogate Model-Based Uncertainty Quantification for a Helical Gear Pair." In Lecture Notes in Mechanical Engineering, 191–207. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77256-7_16.
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AbstractCompetitive industrial transmission systems must perform most efficiently with reference to complex requirements and conflicting key performance indicators. This design challenge translates into a high-dimensional multi-objective optimization problem that requires complex algorithms and evaluation of computationally expensive simulations to predict physical system behavior and design robustness. Crucial for the design decision-making process is the characterization, ranking, and quantification of relevant sources of uncertainties. However, due to the strict time limits of product development loops, the overall computational burden of uncertainty quantification (UQ) may even drive state-of-the-art parallel computing resources to their limits. Efficient machine learning (ML) tools and techniques emphasizing high-fidelity simulation data-driven training will play a fundamental role in enabling UQ in the early-stage development phase.This investigation surveys UQ methods with a focus on noise, vibration, and harshness (NVH) characteristics of transmission systems. Quasi-static 3D contact dynamic simulations are performed to evaluate the static transmission error (TE) of meshing gear pairs under different loading and boundary conditions. TE indicates NVH excitation and is typically used as an objective function in the early-stage design process. The limited system size allows large-scale design of experiments (DoE) and enables numerical studies of various UQ sampling and modeling techniques where the design parameters are treated as random variables associated with tolerances from manufacturing and assembly processes. The model accuracy of generalized polynomial chaos expansion (gPC) and Gaussian process regression (GPR) is evaluated and compared. The results of the methods are discussed to conclude efficient and scalable solution procedures for robust design optimization.
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Jung, J., J. Kato, K. Terada, and T. Kyoya. "Strength evaluation of discontinuous rock mass by multi-scale limit load analysis." In Harmonising Rock Engineering and the Environment, 663–66. CRC Press, 2011. http://dx.doi.org/10.1201/b11646-118.
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Tsiligaridis, John. "A Framework for Semi-Autonomous Servers in the Wireless Network Environment." In Open Information Management, 374–96. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-246-6.ch017.
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The problem of server performance in a contemporary, rapidly developed and multi-discipline environment is examined. Multiple requests in a very short period of time increase the number of connections and push the server to the limit. Nowadays servers’ ability to work semi autonomously, in regards to the decision of the appropriate query plan and the provision of the effective data location, plays a significant role for the query and network performance. For autonomous server operations many of the offered services need to be self-managed. Data sources’ administration during the execution of the query plan becomes of primary interest especially for the starting query server. The proposed server grouping process, server’s scale up capabilities and the application of Data Mining concepts in a wireless environment can contribute a lot to the optimization of the query plan and also increase server independence. Various methods of distributed data exploration and exploitation that support server’s semi-autonomous operational behavior are developed. Simulation results are provided. This chapter covers a significant part of cooperative domains in the area of information management and can offer integrated solutions very attractive to the mobile users.
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Tsiligaridis, John. "A Framework for Semi-Autonomous Servers in the Wireless Network Environment." In Networking and Telecommunications, 351–70. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-60566-986-1.ch024.
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The problem of server performance in a contemporary, rapidly developed and multi-discipline environment is examined. Multiple requests in a very short period of time increase the number of connections and push the server to the limit. Nowadays servers’ ability to work semi autonomously, in regards to the decision of the appropriate query plan and the provision of the effective data location, plays a significant role for the query and network performance. For autonomous server operations many of the offered services need to be self-managed. Data sources’ administration during the execution of the query plan becomes of primary interest especially for the starting query server. The proposed server grouping process, server’s scale up capabilities and the application of Data Mining concepts in a wireless environment can contribute a lot to the optimization of the query plan and also increase server independence. Various methods of distributed data exploration and exploitation that support server’s semi-autonomous operational behavior are developed. Simulation results are provided. This chapter covers a significant part of cooperative domains in the area of information management and can offer integrated solutions very attractive to the mobile users.
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"Introduction—Contemporary Archaeology and the City: Creativity, Ruination, and Political Action." In Contemporary Archaeology and the City, edited by Laura McAtackney and Krysta Ryzewski. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198803607.003.0007.
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Changes in Detroit’s motor vehicle industries affect counterparts in Tokyo, struggling financial sectors in Athens rattle the economy of Dublin, construction booms in Vancouver stimulate investments by Hong Kong speculators, uprisings by Berlin artists against ‘creative’ redevelopment projects inspire protests by graffiti artists in Mexico City, and inadequate water supplies in greater Los Angeles limit the availability of imported foodstuffs for consumers in Delhi. The contemporary city is essentially an (post-)industrial, modern, and interconnected place where capitalist accumulation, growth, and decline often operate simultaneously, are experienced locally, and resonate globally leaving material traces on urban and associated hinterland landscapes. With the majority of the world’s population now dwelling in cities, historical and future-oriented urban identities face global challenges associated with the logistics and inequalities of deindustrialization. The fast pace of change in cities, as well as the tremendous scale of urban landscapes and the complexities of personal interactions with them, poses an unrivalled challenge to archaeologists whose work begins with contemporary remains. Contemporary Archaeology and the City foregrounds the archaeological study of (post-) industrial and other urban transformations through a diverse, international collection of case studies on present-day cities. The deep historical roots of citizenship in contemporary cities directly affect how communities craft notions of belonging within urban ecologies in the present. For example, the former industrial stronghold of East Belfast has experienced decades-long post-industrial economic decline alongside longstanding sectarian tensions. However, the arrival of new immigrant populations have shifted loyalist narratives in working class neighbourhoods from an identity defined by a self-conceived progressive ethos to one that asserts exclusionary material boundaries around an increasingly inward-looking, defensive community (McAtackney, Chapter 9). Meanwhile, Detroit’s built environment and cultural heritage suffer at the hands of an ongoing, decadeslong social disaster perpetuated by a constellation of political corruption, economic mismanagement, and legacies of racial conflicts. While the media perpetuates inaccurate portrayals of Detroit and other comparable cities as landscapes of abandonment, where people and built environments are increasingly absent, the contributors to this volume adopt a more nuanced approach. They envisage post-industrial cities as variably inhabited places and emergent ecologies—hybrid metropolises that expand and contract over the course of multi-generational life cycles—places that are complicated by conceptual divisions between city and nature, industry and creativity, sustainability and profitability (Millington 2013: 279; Ryzewski 2016; see Ryzewski, Chapter 3).
Conference papers on the topic "Multi-scale limit"
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Terry, Joel, Guillem Carles Santacana, and Andy Harvey. "Multi-scale Aberration Corrected Imaging of the Retina." In Imaging Systems and Applications. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/isa.2022.ith5d.2.
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Multi-scale imaging promises wide-field imaging of the retina with a space-bandwidth product that approaches the Fresnel limit. We describe an implementation that achieves 10× improvement in the space-bandwidth product compared to current retinal imaging systems.
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Gao, Shuang, Ruxin Dai, Wenjing Cao, and Hongjie Jia. "Multi-time Scale Charging Control of Electric Vehicles Considering Electricity Market Incentives and Frequency Limit." In 2022 IEEE/IAS Industrial and Commercial Power System Asia (I&CPS Asia). IEEE, 2022. http://dx.doi.org/10.1109/icpsasia55496.2022.9949827.
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Cang, Ruijin, Aditya Vipradas, and Yi Ren. "Scalable Microstructure Reconstruction With Multi-Scale Pattern Preservation." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-68286.
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A key challenge in computational material design is to optimize for particular material properties by searching in an often high-dimensional design space of microstructures. A tractable approach to this optimization task is to identify an encoder that maps from microstructures, which are 2D or 3D images, to a lower-dimensional feature space, and a decoder that generates new microstructures based on samples from the feature space. This two-way mapping has been achieved through feature learning, as common features often exist in microstructures from the same material system. Yet existing approaches limit the size of the generated images to that of the training samples, making it less applicable to designing microstructures at an arbitrary scale. This paper proposes a hybrid model that learns both common features and the spatial distributions of them. We show through various material systems that unlike existing reconstruction methods, our method can generate new microstructure samples of arbitrary sizes that are both visually and statistically close to the training samples while preserving local microstructure patterns.
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Guo, Jing-Ming, and Chia-Hsiang Lin. "Nighttime image dehazing based on improved erosion dark channel and multi-scale clipping limit histogram equalization." In International Workshop on Advanced Image Technology 2021, edited by Wen-Nung Lie, Qian Kemao, Jae-Gon Kim, and Masayuki Nakajima. SPIE, 2021. http://dx.doi.org/10.1117/12.2591325.
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Wang, Yuxin, Hongtao Xie, Zilong Fu, and Yongdong Zhang. "DSRN: A Deep Scale Relationship Network for Scene Text Detection." In Twenty-Eighth International Joint Conference on Artificial Intelligence {IJCAI-19}. California: International Joint Conferences on Artificial Intelligence Organization, 2019. http://dx.doi.org/10.24963/ijcai.2019/133.
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Nowadays, scene text detection has become increasingly important and popular. However, the large variance of text scale remains the main challenge and limits the detection performance in most previous methods. To address this problem, we propose an end-to-end architecture called Deep Scale Relationship Network (DSRN) to map multi-scale convolution features onto a scale invariant space to obtain uniform activation of multi-size text instances. Firstly, we develop a Scale-transfer module to transfer the multi-scale feature maps to a unified dimension. Due to the heterogeneity of features, simply concatenating feature maps with multi-scale information would limit the detection performance. Thus we propose a Scale Relationship module to aggregate the multi-scale information through bi-directional convolution operations. Finally, to further reduce the miss-detected instances, a novel Recall Loss is proposed to force the network to concern more about miss-detected text instances by up-weighting poor-classified examples. Compared with previous approaches, DSRN efficiently handles the large-variance scale problem without complex hand-crafted hyperparameter settings (e.g. scale of default boxes) and complicated post processing. On standard datasets including ICDAR2015 and MSRA-TD500, the proposed algorithm achieves the state-of-art performance with impressive speed (8.8 FPS on ICDAR2015 and 13.3 FPS on MSRA-TD500).
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Argento, Giulia, Cees W. J. Oomens, and Frank P. T. Baaijens. "Optimal Boundary Conditions for the Multi-Scale Finite Element Analysis of Fibrous Scaffolds for Heart Valve Tissue Engineering." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53238.
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Although existing valve prostheses generally have resulted in enhanced survival and quality of life, they have serious drawbacks that limit their long-term efficacy. These include thrombo-embolic complications requiring lifelong anticoagulation in case of mechanical valves, limited durability due to calcification and structural failure in case of bioprostheses and structural deterioration and shortage of donor material when using a homograft. In addition, the inability to grow restricts the application of currently available prostheses in pediatric patients. Heart valve tissue engineering (TE) is a promising alternative to create living valves that may have the capacity to grow and remodel. The traditional TE approach requires the growth of tissue on a scaffold in a bioreactor before implantation (1).
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Rahmati, M. T., G. Alfano, and H. Bahai. "Small-Scale FE Modelling for the Analysis of Flexible Risers." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41825.
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Flexible risers which are used for transporting oil and gas between the seabed and surface in ultra-deep waters have a very complex internal structure. Therefore, accurate modeling of their behaviour is a great challenge for the oil and gas industry. Constitutive laws based on beam models which allow the large-scale dynamics of pipes to be related to the behaviour of its internal components can be used for multi-scale analysis of flexible risers. An integral part of these models is the small-scale FE model chosen and the detailed implementation of the boundary conditions. The small scale FE analyses are typically carried out on models of up to a few meters length. The computational requirements of these methods limit their applications for only multi-scale structural analysis based on a sequential approach. For nested multi-scale approaches (i.e. the so called FE2 method) and for multi-scale multi-physic analyses, e.g. fluid structure interaction modeling of flexible risers, more efficient methods are required. The emphasis of the present work is on a highly efficient small-scale modelling method for flexible risers. By applying periodic boundary conditions, only a small fraction of a flexible pipe is used for detailed analysis. The computational model is firstly described. Then, the capability of the method in capturing the detailed nonlinear effects and the great advantage in terms of significant CPU time saving entailed by this method are demonstrated. For proof of concept the approach is applied on a simplified 3-layer pipe made of inner and outer polymer layers and an intermediate armour layer made of 40 steel tendons.
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Bandstra, Daryl, Alex Fraser, and Juan S. Rojas. "Subset Simulation of Pipeline Corrosion, Crack, and Dent Defects Considering Multiple Limit States With Large-Scale Validation." In 2022 14th International Pipeline Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/ipc2022-87255.
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Abstract Structural reliability is an engineering method that focuses on the calculation and prediction of the probability of failure for a structural system. Structural reliability is used by many pipeline operators to assess the probability of failure, and these probability of failure estimates are then used to manage safety, environmental, and operational risks for threats such as corrosion, cracking, and third-party damage. In the structural reliability approach, the probability of failure is obtained from a multi-dimensional integral, for which the solution is commonly estimated numerically using Direct Monte Carlo (DMC) simulation. DMC is straight-forward and robust but requires a significant amount of computational effort to estimate small probabilities, which are typical of threats to pipeline integrity. Subset Simulation is an approach that improves on the efficiency issues of DMC by representing the rare event probability as the product of a number of more frequent events, which are each estimated separately. Previous work published at IPC in 2020 by Bandstra and Fraser [1] showed very close agreement between DMC and Subset Simulation for a single defect reference case with a single limit state. This study extends that initial work by applying Subset Simulation to various failure models for a variety of pipeline defects. Subset Simulation is applied to the CSA corrosion model, PRCI MAT-8 crack model, and the EPRG dent failure model, and the performance is evaluated by comparing the results to DMC. For each of these comparisons, simulations are performed across a large-scale grid of validation cases that consider a range of pipeline and defect sizes. An approach that utilizes Subset Simulation to handle multiple limit states is also presented and applied for relevant failure models and the results are evaluated against DMC.
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Dey, Animesh, and Robert Tryon. "Confidence Estimates due to Uncertainty in Multi-Disciplinary Computational Analysis." In ASME 2013 Conference on Frontiers in Medical Devices: Applications of Computer Modeling and Simulation. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fmd2013-16036.
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Simulation-based design and certification is fundamentally about making decisions with uncertainty. However, minimizing uncertainty comes at a price — more testing to better define the variability in input parameters, higher fidelity analyses at a finer scale to limit the uncertainty in the physics, etc. Variability in each input parameter does not affect the uncertainty in the system response equally. Nor does every model refinement reduce the uncertainty in the system response. This paper presents a computational methodology that estimates the sensitivity of uncertainty in input variables and the sensitivity of modeling approximations to the final output. In the current age of large multi-disciplinary virtual simulation, this is useful in determining how to minimize overall uncertainty in analytical predictions. In addition, the methodology can be used to optimize for the best use of computational and testing resources to arrive at most robust predictions.
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Fuglem, Mark, Martin Richard, and Jan Thijssen. "Challenges Implementing ISO 19906 for Probabilistic Assessment of Multi-year Sea Ice Loads on Sloping Structures." In SNAME 11th International Conference and Exhibition on Performance of Ships and Structures in Ice. SNAME, 2014. http://dx.doi.org/10.5957/icetech-2014-154.
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The ISO standard ISO 19906:2010 provides guidance for determining design loads for offshore structures in arctic and sub-arctic regions, using both deterministic and probabilistic approaches. References are provided for models of both first and multi-year ice loads on both vertically-faced and sloping structures. ISO 19906 indicates that consideration should be given to limit stresses at the ice structure interface based on the dominating ice failure mechanisms, limit forces associated with the available driving force that can act on the interacting ice floe due to wind, currents and surrounding ice, and the kinetic energy of the impacting feature. Analyses show that the kinetic energy of an impacting multi-year floe driven by surrounding ice will result in larger loads than those from driving forces alone. In order to determine penetrations and maximum loads, it is then necessary to consider the variation in load with penetration during an impact. In the case of multi-year ice loads on sloping structures, full-scale data to properly validate models is lacking. Several models are available that estimate maximum loads for level ice interactions with sloping structures. These models can partially account for rubble forming on the structure during the interaction thereby increasing loads, though the ability to estimate rubble heights for different structure shapes and ice conditions at present is limited. In the case of multi-year ridges, several models are available that estimate the maximum load during the interaction of a prismatic beam shaped ridge contacting a conical structure. Data and model for loads from more realistic multi-year ridge shapes are lacking. Additionally, the influence of rubble existing on the structure at the time the ridge impacts is not explicitly considered. This paper examines issues in determining probabilistic design loads for multi-year interactions with sloping structures and presents sensitivity results for key assumptions and parameters. The analyses were carried out using the Sea Ice Loads Software (SILS) developed by C-CORE as part of a Joint Industry Project (JIP) to implement ice load models referenced in ISO 19906 within a probabilistic framework for the purpose of determining design loads. Interpretation was required where ISO 19906 does not provide explicit details on the models and probabilistic implementation. Monte-Carlo simulation was selected for carrying out probabilistic calculations of design loads as this approach is robust.
Reports on the topic "Multi-scale limit"
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Stakes, Keith, Keith Stakes, Julie Bryant, Nick Dow, Jack Regan, and Craig Weinschenk. Analysis of the Coordination of Suppression and Ventilation in Multi-Family Dwellings. UL Firefighter Safety Research Institute, June 2020. http://dx.doi.org/10.54206/102376/ympj4047.
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The majority of the existing full-scale fire service research studied the impact of tactics on the residential fireground, specifically in single-family structures. This study builds upon prior research by conducting thirteen experiments in three-story, multi-family dwellings to quantify the impact of coordination between ventilation and suppression actions. Experiments were conducted in four, garden-style apartment buildings; each of which had two lower-level units, four first-floor units, and four second-floor units. The apartments shared a common stairwell that was enclosed for all of the experiments in this study. To examine the effectiveness of tactics in the fire apartment, common stairwell and applicable exposure apartments, four experiments were conducted in lower-level apartments, seven were conducted in first-floor apartments, and two were conducted in second-floor apartments including both bedroom and kitchen/living room fires. The fire size varied based on the amount of initial ventilation provided. The main control variables included the location of initial water application, the ventilation method, and the timing of ventilation relative to water application. The suppression tactics included interior water application, exterior water application followed by interior water application, and a combined interior and exterior water application. The ventilation tactics examined in these experiments included horizontal, vertical, positive pressure, and hydraulic ventilation. Similar to previous experiments in acquired single-family structures, there was no meaningful increase in temperature outside of fire rooms when ventilation tactics were executed in close coordination with (shortly after or shortly before) the onset of suppression. In contrast, for experiments where ventilation occurred with delayed suppression, temperature exposures increased throughout the fire apartment, and in experiments where the apartment door was left open, temperatures and carbon monoxide exposures increased throughout the common stairwell. Suppression actions, whether interior or exterior, resulted in a decrease in temperatures and gas concentrations at locations where occupants may potentially be located. The enclosed common stairwell, a unique feature of this experimental series, acted as capture of combustion products. Opening the apartment door to gain access should be thought of as an important ventilation action, both in terms of its potential to cause fire growth and its potential for smoke movement into the stairwell, limiting the egress for potentially trapped occupants in exposure units. Tactics such as door control, positive pressure ventilation, and hydraulic ventilation which were used both simultaneous with and sequentially post-suppression were shown to limit gas flows into the stairwell. After effective suppression, structure ventilation operations should similarly be cognizant of gas flows, with the aim of establishing flow throughout all areas where occupants may be located.
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Herbert, Sian. Reducing Criminal Violence Through Public Sector-led Multisectoral Approaches. Institute of Development Studies, October 2021. http://dx.doi.org/10.19088/k4d.2022.043.
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The last decades have seen increased consensus for the need to understand and address violence through a public health approach, and a preventative approach, as embodied by Sustainable Development Goal (SDG) 16. This necessitates a multi-sector and multi-stakeholder approach, yet poor governance continues to threaten progress on this agenda. Many policy approaches to urban violence tend to take an approach that is either place-based; people-based; or behaviour-based and include a range of initiatives. The INSPIRE initiative is a key global response to tackling violence against women (VAW) and violence against children (VAC) A multisector approach is needed to address the complexity and multifactorial origins of violence. Yet multisector engagement can complicate institutional responses due to different goals, concepts, instruments, etc. Increased collaboration and joined-up approaches across government departments have led to changes in institutions and approaches. The literature base on violence prevention initiatives is varied and uneven across the different types of violence, e.g. with more literature available on interventions focussed on interpersonal and urban violence compared to organised crime-related violence. Evaluations are limited and face many methodological challenges (Cuesta & Alda, 2021) – e.g. the scale and complexity of violence limits the extent to which interventions can be rigorously evaluated or comparable, and most focus on interventions in the Global North. Most importantly, the literature base for this specific question – focussed on the wider institutional context and lessons for a multisectoral approach – is very limited, as most of the available literature focusses on lessons relating to the outcomes of the interventions. In line with the operational focus of this paper, this review draws mainly on practitioner and policy publications. The approaches, interventions, and lessons detailed below are illustrative and are not comprehensive of the many complex lessons relating to this broad area of programming.
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RESEARCH ON DYNAMIC LOAD CARRYING CAPACITY OF ASSEMBLED INTERNAL STIFFENING WIND TURBINE TOWER BASED ON MULTI-SCALE MODELING. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.513.
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"The development of wind power technology requires higher and larger wind turbines, which requires the bearing tower to increase its height and diameter. The assembled internal stiffened wind turbine tower divides the tower into multiple arc plates along the longitudinal direction, which can be easy transported to the site for assembly. That can solve the problem of height limit in highway transportation. At the same time, the internal stiffener provides better stability and can replace the bottom tower section of conventional wind turbine tower. In this study, the tower section of assembled internal stiffened wind turbine is modeled, and the longitudinal segmented tower section is assembled to the actual full-scale tower section model for nonlinear dynamic analysis. The influence of weld is considered by multi-scale modeling, combined with the plastic damage theory of steel materials. The whole collapse process of tower wall instability and deformation failure of wind turbine tower under the extreme wind condition is simulated, and the influence of various parameters of tower section on its bearing capacity is analysed. The damage position and damage development during tower collapse are predicted by using plastic damage theory, so as to provide reference for the design of assembled internally stiffened wind turbine tower."
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RESEARCH ON DYNAMIC LOAD CARRYING CAPACITY OF ASSEMBLED INTERNAL STIFFENING WIND TURBINE TOWER BASED ON MULTI-SCALE MODELING. The Hong Kong Institute of Steel Construction, March 2023. http://dx.doi.org/10.18057/ijasc.2023.19.1.11.
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The development of wind power technology requires higher and larger wind turbines, which requires the bearing tower to increase its height and diameter. The assembled internal stiffened wind turbine tower divides the tower into multiple arc plates along the longitudinal direction, which can be easy transported to the site for assembly. That can solve the problem of height limit in highway transportation. At the same time, the internal stiffener provides better stability and can replace the bottom tower section of conventional wind turbine tower. In this study, the tower section of assembled internal stiffened wind turbine is modeled, and the longitudinal segmented tower section is assembled to the actual full-scale tower section model for nonlinear dynamic analysis. The influence of weld is considered by multi-scale modeling, combined with the plastic damage theory of steel materials. The whole collapse process of tower wall instability and deformation failure of wind turbine tower under the extreme wind condition is simulated, and the influence of various parameters of tower section on its bearing capacity is analysed. The damage position and damage development during tower collapse are predicted by using plastic damage theory, so as to provide reference for the design of assembled internally stiffened wind turbine tower.