Thematische Bibliographien / Experimental and numerical approaches

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Auswahl der wissenschaftlichen Literatur zum Thema „Experimental and numerical approaches“

Autor: Grafiati

Veröffentlicht am 15. März 2025

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Zeitschriftenartikel zum Thema "Experimental and numerical approaches"

Nesládek, M., M. Španiel, J. Jurenka, J. Růžička und J. Kuželka. „Fretting fatigue – Experimental and numerical approaches“. International Journal of Fatigue 44 (November 2012): 61–73. http://dx.doi.org/10.1016/j.ijfatigue.2012.05.015.

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Chiew, Yee-Meng, Jihn-Sung Lai und Oscar Link. „Experimental, Numerical and Field Approaches to Scour Research“. Water 12, Nr. 6 (19.06.2020): 1749. http://dx.doi.org/10.3390/w12061749.

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Scour, which represents a fascinating and complex engineering problem involving a number of physical mechanisms and interactions, has motivated a vast amount of research following different but complementary methodological approaches such as experimental, numerical, and field methods. Far from being completely understood, scour remains one of the main hazards for many structures such as bridges, submarine pipelines, offshore wind turbines, etc. Thus, scour is currently a very active field of research with important open questions that are unanswered and practical challenges to be tackled. This Special Issue aims to bridge knowledge gaps by collecting fourteen papers to provide a wide view of scour types and different research approaches, with innovative ideas and inferences.

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Badurowicz, Przemysław, und Dawid Pacek. „Determining Ricocheting Projectiles’ Temperature Using Numerical and Experimental Approaches“. Materials 15, Nr. 3 (25.01.2022): 928. http://dx.doi.org/10.3390/ma15030928.

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This paper describes the process of creating a numerical FEM (finite element method) model of the 5.56 × 45 mm SS109 projectile. The model was used to calculate the temperatures occurring in the projectile materials during the impact on the steel plate at an angle of 45°. The purpose of the investigation is to estimate the ability of a ricocheting projectile to cause ignition. For the same projectile, experimental tests were also carried out under the conditions adopted for the numerical investigation in order to validate the FEM model. During the experiment, temperature was measured with a thermal camera; the phenomenon was also recorded with a colour high-speed camera.

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Lin, Shu-Li, Sheng-Yang Lee, Long-Yi Lee, Wen-Ta Chiu, Che-Tong Lin und Haw-Ming Huang. „Vibrational analysis of mandible trauma: experimental and numerical approaches“. Medical & Biological Engineering & Computing 44, Nr. 9 (22.08.2006): 785–92. http://dx.doi.org/10.1007/s11517-006-0095-4.

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Gomes, Hugo Dutra, Maria Carolina dos Santos Freitas, Luciano Pessanha Moreira, Flavia de Paula Vitoretti und Jose Adilson de Castro. „Deformations Limits Analysis of Sheet Metal Manufatured through the Incremental Forming Process“. Materials Science Forum 899 (Juli 2017): 272–77. http://dx.doi.org/10.4028/www.scientific.net/msf.899.272.

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The present study is primarily engaged in the implementation of the incremental stamping process in a computerized numeric control This paper presents two different approaches to this forming process, an experimental and other numerical. Experimental used by the computer numerical control to perform the printing process and performs numerical simulations of the process using the finite element method. Some parameters are analyzed in both approaches, such as product geometry effects, tool geometry, tool speed, tool path, contact conditions and mechanical properties of the materials.

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KHARIF, C., J. P. GIOVANANGELI, J. TOUBOUL, L. GRARE und E. PELINOVSKY. „Influence of wind on extreme wave events: experimental and numerical approaches“. Journal of Fluid Mechanics 594 (14.12.2007): 209–47. http://dx.doi.org/10.1017/s0022112007009019.

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The influence of wind on extreme wave events in deep water is investigated experimentally and numerically. A series of experiments conducted in the Large Air–Sea Interactions Facility (LASIF-Marseille, France) shows that wind blowing over a short wave group due to the dispersive focusing of a longer frequency-modulated wavetrain (chirped wave packet) may increase the time duration of the extreme wave event by delaying the defocusing stage. A detailed analysis of the experimental results suggests that extreme wave events may be sustained longer by the air flow separation occurring on the leeward side of the steep crests. Furthermore it is found that the frequency downshifting observed during the formation of the extreme wave event is more important when the wind velocity is larger. These experiments have pointed out that the transfer of momentum and energy is strongly increased during extreme wave events.Two series of numerical simulations have been performed using a pressure distribution over the steep crests given by the Jeffreys sheltering theory. The first series corresponding to the dispersive focusing confirms the experimental results. The second series which corresponds to extreme wave events due to modulational instability, shows that wind sustains steep waves which then evolve into breaking waves. Furthermore, it was shown numerically that during extreme wave events the wind-driven current could play a significant role in their persistence.

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Souza, Andrews, Eduardo Marques, Carlos Balsa und João Ribeiro. „Characterization of Shear Strain on PDMS: Numerical and Experimental Approaches“. Applied Sciences 10, Nr. 9 (10.05.2020): 3322. http://dx.doi.org/10.3390/app10093322.

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Polydimethylsiloxane (PDMS) is one of the most popular elastomers and has been used in different fields, especially in biomechanics research. Among the many interesting features of this material, its hyperelastic behavior stands out, which allows the use of PDMS in various applications, like the ones that mimic soft tissues. However, the hyperelastic behavior is not linear and needs detailed analysis, especially the characterization of shear strain. In this work, two approaches, numerical and experimental, were proposed to characterize the effect of shear strain on PDMS. The experimental method was implemented as a simple shear testing associated with 3D digital image correlation and was made using two specimens with two thicknesses of PDMS (2 and 4 mm). A finite element software was used to implement the numerical simulations, in which four different simulations using the Mooney–Rivlin, Yeoh, Gent, and polynomial hyperelastic constitutive models were performed. These approaches showed that the maximum value of shear strain occurred in the central region of the PDMS, and higher values emerged for the 2 mm PDMS thickness. Qualitatively, in the central area of the specimen, the numerical and experimental results have similar behaviors and the values of shear strain are close. For higher values of displacement and thicknesses, the numerical simulation results move further away from experimental values.

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Stanciu, Mariana Domnica, Silviu Marian Nastac, Voichita Bucur, Mihai Trandafir, Gheorghe Dron und Alina Maria Nauncef. „Dynamic Analysis of the Musical Triangles—Experimental and Numerical Approaches“. Applied Sciences 12, Nr. 12 (20.06.2022): 6275. http://dx.doi.org/10.3390/app12126275.

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This paper addresses the experimental and numerical dynamic analysis of curved bars used as percussion musical instruments. These structures are known as triangles, being made of various metal materials. The study was based on the experimental analysis of the dynamic response over time and the frequency of three types of triangles, different in material and size. Subsequently, finite element analysis of the same structures modeled with the SimCenter 12 program was performed. The results were compared, highlighting the contribution of material type and geometry in obtaining vibration modes, frequency spectrum, and structural damping coefficient. Between the experimental and the numerical analysis, the obtained errors were below 2.2% in terms of their natural frequencies. The study also highlights the complementarity of the two methods in understanding the vibration modes of triangles.

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Fanara, Arthur, Luc Courard, Frédéric Collin und Julien Hubert. „Transfer properties in recycled aggregates concrete: Experimental and numerical approaches“. Construction and Building Materials 326 (April 2022): 126778. http://dx.doi.org/10.1016/j.conbuildmat.2022.126778.

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de Camargo, Felipe Vannucchi. „Survey on Experimental and Numerical Approaches to Model Underwater Explosions“. Journal of Marine Science and Engineering 7, Nr. 1 (15.01.2019): 15. http://dx.doi.org/10.3390/jmse7010015.

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The ability of predicting material failure is essential for adequate structural dimensioning in every mechanical design. For ships, and particularly for military vessels, the challenge of optimizing the toughness-to-weight ratio at the highest possible value is essential to provide agile structures that can safely withstand external forces. Exploring the case of underwater explosions, the present paper summarizes some of the fundamental mathematical relations for foreseeing the behavior of naval panels to such solicitation. A broad state-of-the-art survey links the mechanical stress-strain response of materials and the influence of local reinforcements in flexural and lateral-torsional buckling to the hydrodynamic relations that govern the propagation of pressure waves prevenient from blasts. Numerical simulation approaches used in computational modeling of underwater explosions are reviewed, focusing on Eulerian and Lagrangian fluid descriptions, Johnson-Cook and Gurson constitutive materials for naval panels, and the solving methods FEM (Finite Element Method), FVM (Finite Volume Method), BEM (Boundary Element Method), and SPH (Smooth Particle Hydrodynamics). The confrontation of experimental tests for evaluating different hull materials and constructions with formulae and virtual reproduction practices allow a wide perception of the subject from different yet interrelated points of view.

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Dissertationen zum Thema "Experimental and numerical approaches"

Huan, Xun. „Numerical approaches for sequential Bayesian optimal experimental design“. Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101442.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 175-186).
Experimental data play a crucial role in developing and refining models of physical systems. Some experiments can be more valuable than others, however. Well-chosen experiments can save substantial resources, and hence optimal experimental design (OED) seeks to quantify and maximize the value of experimental data. Common current practice for designing a sequence of experiments uses suboptimal approaches: batch (open-loop) design that chooses all experiments simultaneously with no feedback of information, or greedy (myopic) design that optimally selects the next experiment without accounting for future observations and dynamics. In contrast, sequential optimal experimental design (sOED) is free of these limitations. With the goal of acquiring experimental data that are optimal for model parameter inference, we develop a rigorous Bayesian formulation for OED using an objective that incorporates a measure of information gain. This framework is first demonstrated in a batch design setting, and then extended to sOED using a dynamic programming (DP) formulation. We also develop new numerical tools for sOED to accommodate nonlinear models with continuous (and often unbounded) parameter, design, and observation spaces. Two major techniques are employed to make solution of the DP problem computationally feasible. First, the optimal policy is sought using a one-step lookahead representation combined with approximate value iteration. This approximate dynamic programming method couples backward induction and regression to construct value function approximations. It also iteratively generates trajectories via exploration and exploitation to further improve approximation accuracy in frequently visited regions of the state space. Second, transport maps are used to represent belief states, which reflect the intermediate posteriors within the sequential design process. Transport maps offer a finite-dimensional representation of these generally non-Gaussian random variables, and also enable fast approximate Bayesian inference, which must be performed millions of times under nested combinations of optimization and Monte Carlo sampling. The overall sOED algorithm is demonstrated and verified against analytic solutions on a simple linear-Gaussian model. Its advantages over batch and greedy designs are then shown via a nonlinear application of optimal sequential sensing: inferring contaminant source location from a sensor in a time-dependent convection-diffusion system. Finally, the capability of the algorithm is tested for multidimensional parameter and design spaces in a more complex setting of the source inversion problem.
by Xun Huan.
Ph. D.

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Duthil, Eric Patxi. „Thermoacoustic heat pumping study : experimental and numerical approaches /“. View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20DUTHIL.

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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.
Includes bibliographical references (leaves 122-129). Also available in electronic version. Access restricted to campus users.

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CONTI, BRUNO. „Solid Oxide Fuel Cells: Numerical and Experimental Approaches“. Doctoral thesis, Università degli studi di Genova, 2019. http://hdl.handle.net/11567/943177.

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Solid oxide fuel cell (SOFC) is a promising electrochemical technology that can produce electrical and thermal power with outstanding efficiencies. A systematic synergetic approach between experimental measurements and modelling theory has proved to be instrumental to evaluate performance and correct behaviour of a chemical process, like the ones occurring in SOFC. For this purpose, starting from SIMFC (SIMulation of Fuel Cells) code set-up by PERT-UNIGE (Process Engineering Research Group) for Molten Carbonate Fuel Cells [1], a new code has been set-up for SOFCs based on local mass, energy, charge and momentum balances. This code takes into account the proper reactions occurring in the SOFC as well as new geometries and kinetics thanks to experiments carried out on single cells and stack in ENEA laboratories of C.R. Casaccia and VTT Fuel Cell Lab in Finland. In particular using an innovative experimental setup it has been possible to study experimentally the influence of a multicomponent mixtures on the performance of SOFC and also validate locally a 2-D model developed starting from SIMFC code. The results obtained are good, showing a good agreement between experimental and numerical results. The obtained results are encouraging further studies which allow the model validation on a greater quantity of data and under a wider range of operating conditions.

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Fliegans, Jérôme. „Coercivity of NdFeB-based sintered permanent magnets : experimental and numerical approaches“. Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY071.

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Les aimants permanents Nd-Fe-B sont actuellement les plus puissants du marché. Ils sont indispensables pour des applications telles que les moteurs des véhicules électriques ou les générateurs des éoliennes. Leurs propriétés exceptionnelles viennent des propriétés magnétiques intrinsèques de la phase Nd2Fe14B et de leur microstructure. Cependant, les machines électriques fonctionnent entre 120 et 180°C et les propriétés magnétiques extrinsèques telles que la coercitivité et la rémanence diminuent avec la température. Un moyen d’améliorer la coercitivité des aimants frittés Nd-Fe-B est la substitution du Nd par des terres rares lourdes comme le Dy, afin d’augmenter l’anisotropie magnétocristalline. Néanmoins, le Dy est un matériau critique et un objectif majeur de la recherche est actuellement de développer des aimants possédant d’excellentes propriétés magnétiques extrinsèques et contenant peu de Dy. Cela nécessite une meilleure compréhension du lien entre microstructure et coercitivité. Dans les aimants frittés Nd-Fe-B, un des points-clés est le contrôle de la taille de grain et de la répartition des phases secondaires aux joints de grains de façon à limiter la nucléation du retournement de l’aimantation et à garantir un bon découplage magnétique des grains. La première partie de la thèse est une étude comparative des caractérisations magnétiques en circuit ouvert et fermé réalisées sur des aimants frittés Nd-Fe-B. Les différences de coercitivité observées sont expliquées par les phénomènes de viscosité magnétique et d’effets de champ démagnétisant. La deuxième partie traite du procédé de diffusion aux joints de grains appliqué aux aimants frittés Nd-Fe-B et utilisant des alliages Dy-Co. Des caractérisations microstructurales ont été réalisées en complément de mesures magnétiques afin de déterminer les profils de diffusion et de coercitivité, et ainsi d’établir le lien entre les variations locales de composition chimique et le champ coercitif. De plus, des simulations micromagnétiques ont permis de décrire le retournement de l’aimantation à l’échelle nanométrique dans un modèle simplifié cœur-coquille. Enfin, la dernière partie de la thèse constitue une discussion sur la coercitivité des aimants diffusés au Dy-Co (à gradient de champ coercitif) à l’aide d’un modèle de diffusion et de simulations sur un modèle polycristallin
Nd-Fe-B permanent magnets are the most powerful among all commercially available magnets. They play a significant role in energy applications, such as motors of electric vehicles and generators of windmills. Their outstanding properties come from the excellent intrinsic magnetic properties of the Nd2Fe14B phase and from their microstructure. However, electrical machines operate at about 120-180°C and extrinsic magnetic properties such as coercivity and remanence decrease rapidly with temperature. One way of improving coercivity of Nd-Fe-B sintered magnets is to substitute Nd with a heavy rare earth such as Dy, so as to increase the magnetocrystalline anisotropy. However, Dy is a strategic element and a major objective of the research community is therefore to develop Nd-Fe-B magnets that possess excellent extrinsic magnetic properties with a reduced content of Dy. This requires a better understanding of the link between microstructure and coercivity. The key point is the control of the grain size and the distribution of secondary phases at grain boundaries to prevent magnetization reversal and magnetic coupling. The first part of this thesis concerns a comparison of open-circuit and closed-circuit magnetization measurements carried out on Nd-Fe-B sintered magnets. The observed differences in coercivity values are discussed in terms of magnetic viscosity and demagnetizing field effects. The second part deals with the grain boundary diffusion process performed on Nd-Fe-B sintered magnets using Dy-Co alloys. Microstructural observations and magnetic measurements have been carried out to characterize the diffusion and coercivity profiles and to establish the link between local variations in composition and coercivity. Moreover, micromagnetic simulations have been performed to describe magnetization reversal at the nanoscale in a simple core-shell model. The last part constitutes a discussion about coercivity in graded magnets via a diffusion model and further simulations on a polycrystalline model

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Jrad, Wassim. „Dynamic behavior of thin-walled beams : Analytical, numerical and experimental approaches“. Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0271.

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Les poutres à parois minces à sections ouvertes sont des éléments de base des ouvrages courants en génie civil, de l'automobile et de l'aéronautique. En raison de leur élancement et la forme des sections, elles sont très sensibles à la torsion et aux instabilités aussi bien en statique qu’en dynamique. En dynamique, les modes de vibration en torsion sont plus dominants par rapport au modes de flexion classiques. Pour ces raisons, les défaillances planaires de telles structures sont connues pour être une exception plutôt qu'une règle. Dans ce travail de thèse, on s’intéresse au comportement dynamique de poutres à parois minces et à section ouvertes arbitraires. En se basant sur le modèle de Vlasov qui prend en compte de la torsion et du gauchissement, les équations de mouvement 3D sont dérivées à partir du principe d’Hamilton. Des solutions analytiques originales pour différentes conditions aux limites sont dérivées pour des modes supérieurs en vibrations libres. Dans ces solutions, les effets des termes de rotation inertiels en flexion et torsion sont pris en compte. Pour des cas généraux, un modèle élément fini de poutre 3D est décrit et implémenté. Dans le modèle, un degré de liberté (ddl) est affecté au gauchissement. Toutes les matrices de rigidité masse de base sont calculées par intégration numérique (intégration de Gauss). Dans le modèle, les calculs en vibrations libres et forcées sont possibles. Le modèle est validé par comparaison aux solutions numériques et expérimentaux de la littérature. Une comparaison aux simulations des codes commerciaux est aussi suivie. Afin de valider le modèle théorique et numérique utilisé, une campagne d’essais a été suivie au LEM3 à Metz. Des essais de vibration libre et forcée sont effectués sur des poutres à parois minces avec différentes conditions aux limites. Les solutions analytiques, numériques et les mesures expérimentales sont comparées et validées. Un bon accord entre les différentes solutions est constaté. Le modèle est étendu aux poutres 3D retenues latéralement par des entretoises. Des ressorts élastiques et visqueux 3D sont ajoutés dans le modèle numérique. L'effet des entretoises est étudié dans le but d’améliorer le comportement des poutres à parois minces vis-à-vis des modes indésirables de type flexion latérale et torsion
Thin-walled beams with open section constitute main elements in engineering applications fields as in civil engineering, automotive and aerospace construction. Due to slenderness and cross section shapes, these elements are very sensitive to torsion and instabilities in both statics and dynamics. In dynamics, the torsional and flexural-torsional modes of vibration are often lower frequencies compared to the classical plane pure bending modes. Thus, planar failures of such structures are known to be an exception rather than a rule. In torsion, warping is important and governs the behavior. In this thesis work, we are interested with the dynamic behavior of thin-walled beams with arbitrary open cross sections. Based on the Vlasov’s model accounting for warping, the 3D motion equations are derived from the Hamilton’s principle. Original analytical solutions for different boundary conditions are derived for higher free vibration modes. In these solutions, the effects of the inertial rotation terms in bending and torsion are taken into consideration. For more general cases, a 3D beam finite element model is described and implemented. Compared to conventional 3D beams, warping is considered as an additional Degree Of Freedom (DOF). The mass and stiffness matrices are obtained by numerical integration (Gauss method). In the model, free and forced vibration analyses are possible. The model is validated by comparison with benchmark solutions available in the literature and other numerical results obtained from simulation on commercial codes. In order to validate the present model, laboratory test campaign is undertaken at the LEM3 laboratory in Metz. Tests are carried out on thin-walled beams with different boundary conditions. Free and forced vibration tests are performed using impact hammer and shaker machine. In the presence of arbitrary sections, flexural-torsional vibration modes are observed. The analytical, the numerical and the experimental solutions are compared and validated. Moreover, the numerical and experimental dynamic response spectra are compared. A good agreement between the various solutions is remarked. The model is extended to 3D beams in presence of lateral braces. 3D elastic and viscous springs are added in the finite element model. The effect of the springs is studied in order to improve the behavior of thin-walled beams against undesirable lateral bending and torsion modes

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BOIGUES, MUNOZ CARLOS. „Computational Simulation of Solid Oxide Fuel Cells – Integrating numerical and experimental approaches“. Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/242989.

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Le celle a combustibile ad ossido solido (Solid Oxide Fuel Cells - SOFCs) sono una tecnologia promettente in grado di produrre potenza elettrica e termica con un’efficienza eccezionale. Tuttavia, è necessaria una comprensione più approfondita dei processi fisico-chimici che si verificano all’interno della cella per risolvere la maggior parte dei problemi di degradazione che attualmente impediscono la maturità della tecnologia. Un approccio sistematico e sinergico tra misure sperimentali, l’uso di strumenti di analisi e techniche innovative – con particolare attenzione alla deconvoluzione degli spettri di impedenza elettrochimica (Electrochemical Impedance Spectroscopy - EIS) mediante il metodo della distribuzione dei tempi di rilassamento (Distributed Relaxation Times - DRT) – e teoria modellistica ha dimostrato di essere importante per la stima dei parametri che descrivono le caratteristiche microstrutturali ed elettrochimiche di due tipi di SOFC planari anodo-supportate, una progettata per funzionare ad una temperatura intermedia (750ºC) e l’altra per farlo a bassa temperatura (650ºC). Un macro-modello CFD (Computational Fluid Dynamics) dei campioni testati, che incorpora i parametri ottenuti dalla procedura menzionata, è stato convalidato confrontando le curve di polarizzazione simulate con quelle sperimentali. Questo modello ha dimostrato di essere un valido strumento per ottimizzare la microstruttura delle celle e per stabilire le basi per analizzare gli effetti di potenziali fenomeni di degrado nella cella e, infine, prevedere la generazione di elettricità a lungo termine in condizioni di funzionamento predeterminate. Inoltre, un modello CFD di una cella di tipo tubolare all’interno di un generatore di potenza (cioè, stack SOFC) di 500 Wel ha permesso di apprezzare come un singolo elemento dello stack si comporta in condizioni operative quasi realistiche.
Solid oxide fuel cell (SOFC) is a promising electrochemical technology that can produce electrical and thermal power with outstanding efficiencies, however, a more profound understanding of the physicochemical processes occurring within the cell is necessary to overcome most of the degradation issues currently impeding the maturity of the technology. A systematic synergetic approach between experimental measurements, the use of novel analysis tools and techniques – with special attention to the deconvolution of electrochemical impedance spectroscopy (EIS) spectra by means of the distribution of relaxation times (DRT) method – and modelling theory has proved to be instrumental for the estimation of parameters describing the microstructural and electrochemical properties of two types of planar anode-supported SOFCs, one designed to operate at intermediate temperatures (750ºC) and the other at low temperatures (650ºC). A comprehensive macro-scale computational fluid dynamics (CFD) model of the tested samples incorporating the aforementioned parameters has been validated by confronting the simulated polarization curves with the experimental ones. This model has demonstrated to be a compelling tool to optimize the microstructure of the cells whilst establishing the bases to monitor and analyse the effects of potential degradation phenomena in the cell and predict the electrical output of the cell in the long run under pre-determined operating conditions. Additionally, a CFD model of a tubular-type cell comprised in the power module (i.e. SOFC stack) of a characterised 500Wel power generator has enabled to appreciate how a singular element of the stack behaves under nearly realistic operating conditions.

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Cescatti, Elvis. „Combined experimental and numerical Approaches to the Assessment of historical Masonry Structures“. Doctoral thesis, Università degli studi di Trento, 2016. https://hdl.handle.net/11572/368102.

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The assessment and the conservation of historical masonry structures are very challenging issues. According to the actual methodology, all the phases of the entire process of assessment require efforts and reciprocal comparison in order to understand reliably the structural behaviour and to design effective interventions. This thesis goes through such phases (anamnesis, diagnosis and treatment), introducing some innovations in each step and connecting the experimental experiences to models with the support of some real cases. Three techniques are developed about the knowledge phase, namely sonic test, flat jacks and dynamic identification. Deeper studies have been dedicated to vault systems by means of an extended experimental campaign with five full scale vaults tests and a reverse analysis to better understand the behaviour of structures and, at the same time, the limits of models. Sometime this comparison suggests a lack between model parameters and physical meaning due to modelling approaches (mesh, element type) and parameters (material properties and constitutive laws) and this gap may be fulfil by both local and global tests. From the experimental point of view this work presents a wide range of tests from the local to the global behaviour and varying among non-destructive, minor destructive and destructive tests. On the other hand for models, both linear and non-linear approaches have been adopted looking as well to local and global phenomena. Finally, about the deepest analysis on vaults even the scale of modelling was evaluated with the comparison between macro and meso-scale modelling. In this framework some proposal in kinematic analysis of strengthened vaults were provided. The work carried out allows therefore to compare traditional and more used tools for structural assessment purposes with real and measured experiences helping to validate the current methodology in the safety evaluation of existing buildings.

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Cescatti, Elvis. „Combined experimental and numerical Approaches to the Assessment of historical Masonry Structures“. Doctoral thesis, University of Trento, 2016. http://eprints-phd.biblio.unitn.it/1742/1/PhD_th_Cescatti.pdf.

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Khoueiry, Nicole. „Study of granular platforms behaviour over soft subgrade reinforced by geosynthetics : Experimental and numerical approaches“. Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI027.

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Les géosynthétiques sont utilisés depuis les années 70 dans le renforcement des plateformes granulaires reposant sur des sols de faible portance pour des applications de routes non revêtues. La complexité des mécanismes développés et la diversité des produits de renforcement nécessitent encore d’étudier ces plateformes renforcées. Un essai au laboratoire permettant de tester des plateformes à échelle réelle a été développé. Une plateforme granulaire non revêtue reposant sur un sol de faible portance a été reproduite. Un protocole de mise en place de ce sol a été élaboré pour assurer son homogénéité et la répétabilité des essais. Une instrumentation spécifique a été développée pour collecter le maximum de mesures utiles pour l’interprétation du transfert de charge et du comportement des géogrilles utilisées. Trois types de géogrille ont été testées : une géogrille extrudée et deux géogrilles tricotées de rigidité différente. Après de nombreux essais de faisabilité, dix essais ont été effectués sous un chargement cyclique sur plaque circulaire, la plateforme testée a été placée dans un banc d’essai de 1,8 m de large, 1,9 m de long et 1,1 m de haut. Sur la base du même protocole de mise en œuvre, des essais de circulation avec un Simulateur Accélérateur de Traffic (SAT) ont été effectués. Ce simulateur a été spécifiquement conçu et construit pour cette application. Pour ces essais, la plateforme testée a été placée dans le banc d’essai allongé à 5 m. La plateforme a été soumise à deux types de sollicitations : un chargement cyclique sur plaque et un chargement de circulation. Des essais de répétabilité ont permis de vérifier le protocole mis en place. A partir des essais, plusieurs observations ont pu être faites sur le comportement des plateformes granulaires, le sol peu porteur, et sur l’efficacité du renforcement. De plus, ces essais ont permis de montrer que le chargement de circulation est beaucoup plus endommageant que le chargement sur plaque. Parallèlement à ces essais, un modèle numérique a été développé en se basant sur la méthode des différences finies avec le logiciel FLAC 3D. Cette modélisation a permis de prédire le comportement de la plateforme sous le premier chargement de plaque
Geosynthetics were used since 1970 in the base course reinforcement supported by soft subgrade in unpaved road application. The various factors and parameters influencing the dominant mechanism and its relative contribution on the platform improvement explain the need of more investigations in this topic. In this research work, large-scale laboratory test was developed to study the reinforcement contribution in the unpaved road improvement. Therefore, an unpaved platform was built of 600 mm of artificial subgrade supporting a base course layer. A detailed experimental Protocol was established regarding the soil preparation, the installation and the soils compaction procedure to reproduce the site conditions and insure the platform repeatability for each test. Three geosynthetics were tested first under a cyclic plate load test. Cyclic load was performed on the prepared platform, with a maximum load of 40 kN resulting in a maximum applied pressure of 560 kPa. The platform was subjected to 10,000 cycles with a frequency of 0.77 Hz. An advanced and complete soil instrumentation was provided in order to collect the maximum data needed for thorough analysis. Quality control tests were performed before each test to verify the soil layers homogeneity and properties. Two base course thicknesses were tested under this test condition, 350 and 220 mm. Once the developed protocol was confirmed under the circular plate load tests, further tests using the Simulator Accelerator of Traffic (SAT) were performed. Indeed, the laboratory prepared platform was placed in a larger box of 1.8 m in large, 5 m in length and 1.1 m in height. The prepared platform was subjected to two solicitations: a particular plate and traffic load. The Simulator Accelerator of Traffic was developed specially for this application. A machine that simulates the traffic load under an effective length of 2 m and a velocity of 4 km/h. The two areas were instrumented: the area under the circulation load, and the area under the plat load, located aside. In addition, a numerical model based on the differential element method using FLAC 3D was developed. The model simulated the circular plate load test with the same platform configuration under monotonic load. The results were compared to the first monotonic load applied on the rigid plate experimentally

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Ding, Zhongman. „Numerical and experimental analysis on Resin Injection Pultrusion (RIP) Process - using macroscopic and microscopic approaches /“. The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486399160105717.

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Bücher zum Thema "Experimental and numerical approaches"

Emami, S. D. Thulium-doped fiber amplifier, numerical and experimental approach. New York: Nova Science Publishers, 2011.

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Ratingen, Michiel René van. Mechanical identification of inhomogeneous solids: A mixed numerical experimental approach. Eindhoven: Technische Universiteit Eindhoven, 1994.

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Wang, Hong-Bo. Heat transfer analysis of components of construction exposed to fire: A theoretical, numerical and experimental approach. Salford: University of Salford, 1995.

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Berghaus, Donald. Numerical Methods for Experimental Mechanics. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1473-2.

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Josep, Sol Maria, Beddor Patrice Speeter und Ohala Manjari, Hrsg. Experimental approaches to phonology. New York: Oxford University Press, 2007.

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Josep, Sol Maria, Beddor Patrice Speeter und Ohala Manjari, Hrsg. Experimental approaches to phonology. New York: Oxford University Press, 2007.

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Maria-Josep, Solé, Beddor Patrice Speeter und Ohala Manjari, Hrsg. Experimental approaches to phonology. Oxford: Oxford University Press, 2007.

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Josep, Sol Maria, Beddor Patrice Speeter und Ohala Manjari, Hrsg. Experimental approaches to phonology. New York: Oxford University Press, 2007.

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S, Oran Elaine, und Boris Jay P, Hrsg. Numerical approaches to combustion modeling. Washington, DC: American Institute of Aeronautics and Astronautics, 1991.

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Bequet, Marc C., Hrsg. Teleoperation: Numerical Simulation and Experimental Validation. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2648-9.

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Buchteile zum Thema "Experimental and numerical approaches"

Yoshioka, Keita, Mathias Nest, Daniel Pötschke, Amir Shoarian Sattari, Patrick Schmidt und David Krach. „Numerical Platform“. In GeomInt–Mechanical Integrity of Host Rocks, 63–95. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-61909-1_3.

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AbstractAn essential scientific goal of the GeomInt project is the analysis of potentials and limitations of different numerical approaches for the modelling of discontinuities in the rocks under consideration in order to improve the understanding of methods and their synergies with regard to theoretical and numerical fundamentals. As numerical methods, the “Lattice Element Method” (LEM), the non-continuous discontinuum methods “Discrete Element Method” (DEM), the “Smoothed Particle Hydrodynamics” (SPH), the “Forces on Fracture Surfaces” (FFS) as well as the continuum approaches “Phase-Field Method” (PFM), “Lower-Interface-Method” (LIE), “Non-Local Deformation” (NLD) and the “Hybrid-Dimensional Finite-Element-Method” (HDF) will be systematically investigated and appropriately extended based on experimental results (Fig. 3.1).

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Nwankwo, Chinyere O., und Jeffrey Mahachi. „Analytical and Numerical Approaches in Predicting the Flexural Behaviour of Reinforced Concrete Beams“. In Lecture Notes in Civil Engineering, 1423–35. Cham: Springer Nature Switzerland, 2025. https://doi.org/10.1007/978-3-031-69626-8_119.

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AbstractThe structural design of buildings, bridges and all other civil engineering structures heavily relies on understanding the beam element, particularly its flexural behaviour. This chapter explores both analytical and numerical approaches to predict the flexural behaviour of reinforced concrete beams. Force equilibrium and strain compatibility equations were used for the analytical approach, while ANSYS, a finite element software, was used for the numerical approach. Comprehensive insights into the analysis, from concrete and reinforcing steel material models to mesh sensitivity analysis in the numerical approach, are provided. The analytical and numerical methods used were validated with an experimental case study beam. The load–deflection curve of a reinforced concrete beam obtained from experimental, analytical and numerical approaches is presented and found to have good correlation. The chapter further provides insights into the efficiency and limitations of each method in predicting the beam behaviour. The findings of this study will guide researchers and practitioners in selecting appropriate methodologies for structural analysis problems.

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Senkel, Luise, Andreas Rauh und Harald Aschemann. „Experimental and Numerical Validation of a Reliable Sliding Mode Control Strategy Considering Uncertainty with Interval Arithmetic“. In Variable-Structure Approaches, 87–122. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-31539-3_4.

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Dimovski, Aleksandar S. „Quantitative Program Sketching using Lifted Static Analysis“. In Fundamental Approaches to Software Engineering, 102–22. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99429-7_6.

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AbstractWe present a novel approach for resolving numerical program sketches under Boolean and quantitative objectives. The input is a program sketch, which represents a partial program with missing numerical parameters (holes). The aim is to automatically synthesize values for the parameters, such that the resulting complete program satisfies: a Boolean (qualitative) specification given in the form of assertions; and a quantitative specification that estimates the number of execution steps to termination and which the synthesizer is expected to optimize.To address the above quantitative sketching problem, we encode a program sketch as a program family (a.k.a. software product line) and analyze it by the specifically designed lifted analysis algorithms based on abstract interpretation. In particular, we use a combination of forward (numerical) and backward (termination) lifted analysis of program families to find the variants (family members) that satisfy all assertions, and moreover are optimal with respect to the given quantitative objective. Such obtained variants represent “correct & optimal” sketch realizations.We present a prototype implementation of our approach within the FamilySketcher tool for resolving C sketches with numerical types. We have evaluated our approach on a set of benchmarks, and experimental results confirm the effectiveness of our approach.

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Kastratović, Gordana, Nenad Vidanović, Aleksandar Grbović, Nikola Mirkov und Boško Rašuo. „Numerical Simulation of Crack Propagation in Seven-Wire Strand“. In Computational and Experimental Approaches in Materials Science and Engineering, 76–91. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-30853-7_5.

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Vidakovic, Jelena, Andrija Devic, Nikola Zivkovic, Vladimir Kvrgic und Pavle Stepanic. „Practical Approaches for Robot Dynamic Model Implementation for Control and Simulation Purposes“. In Experimental Research and Numerical Simulation in Applied Sciences, 147–63. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-19499-3_8.

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Baltic, Marija, Jelena Svorcan, Ognjen Pekovic und Toni Ivanov. „Comparative Numerical and Experimental Modal Analysis of Aluminum and Composite Plates“. In Computational and Experimental Approaches in Materials Science and Engineering, 61–75. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-30853-7_4.

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Dimovski, Aleksandar S., Sven Apel und Axel Legay. „A Decision Tree Lifted Domain for Analyzing Program Families with Numerical Features“. In Fundamental Approaches to Software Engineering, 67–86. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-71500-7_4.

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AbstractLifted (family-based) static analysis by abstract interpretation is capable of analyzing all variants of a program family simultaneously, in a single run without generating any of the variants explicitly. The elements of the underlying lifted analysis domain are tuples, which maintain one property per variant. Still, explicit property enumeration in tuples, one by one for all variants, immediately yields combinatorial explosion. This is particularly apparent in the case of program families that, apart from Boolean features, contain also numerical features with large domains, thus giving rise to astronomical configuration spaces.The key for an efficient lifted analysis is a proper handling of variability-specific constructs of the language (e.g., feature-based runtime tests and $$\texttt {\#if}$$ # if directives). In this work, we introduce a new symbolic representation of the lifted abstract domain that can efficiently analyze program families with numerical features. This makes sharing between property elements corresponding to different variants explicitly possible. The elements of the new lifted domain are constraint-based decision trees, where decision nodes are labeled with linear constraints defined over numerical features and the leaf nodes belong to an existing single-program analysis domain. To illustrate the potential of this representation, we have implemented an experimental lifted static analyzer, called SPLNum$$^2$$ 2 Analyzer, for inferring invariants of C programs. An empirical evaluation on BusyBox and on benchmarks from SV-COMP yields promising preliminary results indicating that our decision trees-based approach is effective and outperforms the baseline tuple-based approach.

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Maierhofer, Johannes, Christian Wagner, Thomas Thümmel und Daniel Rixen. „Progress in Calibrating Active Magnetic Bearings with Numerical and Experimental Approaches“. In Mechanisms and Machine Science, 249–61. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99272-3_18.

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Okrouhlík, M. „Impact Induced StressWave Energy Flux – Validation of Numerical and Experimental Approaches“. In Springer Proceedings in Physics, 25–34. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2069-5_3.

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Konferenzberichte zum Thema "Experimental and numerical approaches"

Bonner, Colin, Drew Barret, Ellen Gupta, Khang Tran, Tyler Rizak, Mark Mirotznik und Kelvin J. Nicholson. „Manufacturing Approaches for Experimental Validation of Numerically Designed Conformal Metasurfaces“. In 2024 IEEE International Symposium on Antennas and Propagation and INC/USNC‐URSI Radio Science Meeting (AP-S/INC-USNC-URSI), 1491–92. IEEE, 2024. http://dx.doi.org/10.1109/ap-s/inc-usnc-ursi52054.2024.10686969.

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Conrad, Brett, Tommy Mikalson, Brian Yeung, Ahmed Hassanin und Atul Ganpatye. „Girth Weld Reinforcement Case Study: A Numerical and Experimental Approach“. In 37th International Pipeline Pigging and Integrity Management Conference 2025, 1177–80. Houston, TX, USA: Clarion Technical Conferences, 2025. https://doi.org/10.52202/078572-0064.

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Zhadobov, Maxim, Ronan Sauleau, Yves Le Drean, Stanislav I. Alekseev und Marvin C. Ziskin. „Numerical and experimental approaches to millimeter-wave dosimetry for in vitro experiments“. In 2008 33rd International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz 2008). IEEE, 2008. http://dx.doi.org/10.1109/icimw.2008.4665728.

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Tanaka, Yasunori, Tomoyuki Nakano, Sun Hao, Kentaro Tomita, Yuki Inada, Akiko Kumada, Kunihiko Hidaka, Takayasu Fujino, Katsumi Suzuki und Takeshi Shinkai. „Fundamental studies on switching arcs — Experimental and numerical approaches“. In 2017 4th International Conference on Electric Power Equipment - Switching Technology (ICEPE-ST). IEEE, 2017. http://dx.doi.org/10.1109/icepe-st.2017.8189008.

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Raid, Idir, Sebastien Gallois-Garreignot, Rafael Estevez und Vincent Coutellier. „Seal Rings Toughness Characterization by Numerical and Experimental Approaches“. In 2018 IEEE 68th Electronic Components and Technology Conference (ECTC). IEEE, 2018. http://dx.doi.org/10.1109/ectc.2018.00155.

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Saat, Ahmet, Halime Esra Işık, Ahmet Arslan, Erinç Erdem und Yalın Kaptan. „Numerical and Experimental Approaches for Inertial Particle Separator Design“. In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-103056.

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Abstract Gas turbine engines, especially turboshaft engines, can be exposed to the unfavourable environmental conditions including ingested sand, dust, rain and salt spray etc. that can cause significant deterioration in engine life and affect its performance. Engine Air Particle Separators (EAPS) fitted to intakes are used for protection of engine parts from the ingestion of foreign particles. Since integrated inertial particle separators (IPS), one of the EAPS’s, have more advantageous characteristics compared with other solutions they are widely preferred. The main aim of this article is to provide insight into the aerodynamic design and performance characteristics of the IPS system using both numerical and experimental approaches. Aerodynamic assessment and particle trajectories have been evaluated through two-way coupled CFD analysis. In addition, the effects of different design such as split area factor, ramp angle, and flow rate on IPS system performance have been investigated. Current study also includes experimental investigation of IPS system test facility based on a sectoral geometry with initial measurement results to validate numerical methodology. During the test campaign, detailed aerodynamic measurements have been conducted and global IPS separation efficiencies have been deduced with different sand types. Results have shown that a very good agreement is observed between the numerical approaches and the test results. Proposed methodology can be considered as an initial part of a well-rounded study to achieve robust IPS system design.

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Crespo, Luis G., Sean P. Kenny und Daniel P. Giesy. „A Comparison of Metamodeling Techniques via Numerical Experiments“. In 18th AIAA Non-Deterministic Approaches Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2016. http://dx.doi.org/10.2514/6.2016-0432.

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Zhao, Y., R. S. Brodkey und S. Nakamura. „Study of 3D Mixing Processes by Numerical and Experimental Approaches“. In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31169.

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Mixing vessels are widely used for blending and chemical reactions. Although much has been done on mixing processes, the complex, three-dimensional flow phenomena are still not well understood. The purpose of our first step in this research is the simulation and validation of time-resolved, three-dimensional velocity vector data. Such results are an essential part of the design of mixing systems, but are generally not available to the engineers. The computational work involves direct numerical simulation (DNS) and large eddy simulation (LES) of the Navier-Stokes equations. Later, modeling of the Reynolds averaged Navier-Stokes (RANS) equations will be undertaken as a simplified approach. Simulations and modeling are being validated by experiments. Two flow mixing systems are under investigation. First and most important for validation is an opposed jet flow system that offers some unique characteristics that can be used for validation of DNS/LES simulations. It also has applications in the injection molding of plastics. Second, simulations of impeller driven mixing vessels that are more commonly used in processing are under development. Here the moving mesh system adds complexity. In addition, visualization of both numerical and experimental results, 3-D particle tracking velocimetry (PTV) techniques have been developed. The proposed paper will address the problems in the modeling of chemical mixing and discuss the results of simulation and validation.

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Jamali, Hazim, M. N. Mohammed, H. S. S. Aljibori, Adnan Al-Tamimi, Intisar Swedain Ali, Oday I. Abdullah, M. A. Abdelgnei, Zuhair Nafea Alani und Marwan Salah Hameed. „Vibration Characteristics of Perforated Plate using Experimental and Numerical Approaches“. In 2023 IEEE 8th International Conference on Engineering Technologies and Applied Sciences (ICETAS). IEEE, 2023. http://dx.doi.org/10.1109/icetas59148.2023.10346538.

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Heilig, Georg A., und Michael May. „Comparison of Experimental, Numerical and Analytical approaches to HRAM events“. In AIAA SCITECH 2023 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2023. http://dx.doi.org/10.2514/6.2023-1841.

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Berichte der Organisationen zum Thema "Experimental and numerical approaches"

Ramakrishnan, Aravind, Ashraf Alrajhi, Egemen Okte, Hasan Ozer und Imad Al-Qadi. Truck-Platooning Impacts on Flexible Pavements: Experimental and Mechanistic Approaches. Illinois Center for Transportation, November 2021. http://dx.doi.org/10.36501/0197-9191/21-038.

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Truck platoons are expected to improve safety and reduce fuel consumption. However, their use is projected to accelerate pavement damage due to channelized-load application (lack of wander) and potentially reduced duration between truck-loading applications (reduced rest period). The effect of wander on pavement damage is well documented, while relatively few studies are available on the effect of rest period on pavement permanent deformation. Therefore, the main objective of this study was to quantify the impact of rest period theoretically, using a numerical method, and experimentally, using laboratory testing. A 3-D finite-element (FE) pavement model was developed and run to quantify the effect of rest period. Strain recovery and accumulation were predicted by fitting Gaussian mixture models to the strain values computed from the FE model. The effect of rest period was found to be insignificant for truck spacing greater than 10 ft. An experimental program was conducted, and several asphalt concrete (AC) mixes were considered at various stress levels, temperatures, and rest periods. Test results showed that AC deformation increased with rest period, irrespective of AC-mix type, stress level, and/or temperature. This observation was attributed to a well-documented hardening–relaxation mechanism, which occurs during AC plastic deformation. Hence, experimental and FE-model results are conflicting due to modeling AC as a viscoelastic and the difference in the loading mechanism. A shift model was developed by extending the time–temperature superposition concept to incorporate rest period, using the experimental data. The shift factors were used to compute the equivalent number of cycles for various platoon scenarios (truck spacings or rest period). The shift model was implemented in AASHTOware pavement mechanic–empirical design (PMED) guidelines for the calculation of rutting using equivalent number of cycles.

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Rahai, Hamid, Assma Begum, Jeremy Bonifacio und Ryan Moffit. Experimental Investigations of Wind Shear from Passing a Vehicle. Mineta Transportation Institute, Dezember 2024. https://doi.org/10.31979/mti.2024.2334.

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Wind energy can be harnessed for various commercial and transportation-related applications. This study assessed experimentally the potential of capturing wind energy from the passage of vehicles for electric power generation. Both wind tunnel experiments and field tests were performed. The wind tunnel experiments were performed in an open-circuit low-speed wind tunnel at a free-stream mean velocity of 23 m/s. Five PVC pipes placed adjacent to the wind-blowing domain were used to simulate the columns under a freeway overpass. A scaled Ahmad body (simplified car body model) was used as the vehicle. The spanwise distance between the Ahmad body and the tubes was 0.75 W where W is the width of the vehicle. The middle tube was used as a reference tube for circumferential and vertical pressure measurements. The streamwise locations of the vehicle were according to our previous transient numerical simulations as the vehicle approached and passed the columns at 0.1–0.5 sec. Results showed a significant potential of the transient wind generated from passing vehicles and identified optimized locations for harnessing this wind for electric power generation. Field tests were performed using a moving scaled Ahmad body. The vehicle speed was approximately 22 miles/hr (10 m/s.). Wind measurements were made up to 0.75 W adjacent to a vertical wall with static and total pressure taps. Results verified the corresponding wind tunnel results and showed a maximum transient wind of 10 m/s from the passing of the vehicle. These results were in agreement with our previous simulation results. The experiment results suggest great potential for harnessing the wind from vehicles to generate electric power, benefiting California's renewable energy goals.

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Naderer, Thomas, Alexander Hammer, Wolfgang Roland, Maximilian Zacher und Gerald Berger-Weber. Optimizing modeling the multilayer coextrusion flow of non-newtonian fluids through rectangular ducts: appropriate shear rate definition for a local power law formulation. Universidad de los Andes, Dezember 2024. https://doi.org/10.51573/andes.pps39.gs.ms.4.

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The accuracy of viscosity predictions is a crucial aspect of polymer melt flow modeling and essential for the design of coextrusion die systems. In the field of non-Newtonian fluid modeling for coextrusion flows through rectangular ducts, significant progress has been made in understanding multilayer flow dynamics. Our fundamental research, employing numerical techniques such as the shooting method, finite element method, and finite difference method for flow evaluation, has established a critical base for the field. Our current research advances fluid dynamics by refining our existing numerical solver, specifically developed for multilayer coextrusion flows. We aim to enhance the solver’s performance by implementing more sophisticated calculations of shear rates that go beyond the traditional approach. The traditional approach often relies on average flow velocities and channel heights, which can underrepresent the complexity of experimentally studied polymer multilayer flows. Our study systematically compares various definitions for characteristic shear rates to describe the local shear rate dependent viscosity behavior using, for instance, a local power law model. A thorough error analysis quantifies the accuracy of each model and its predictive limitations for industrially relevant material combinations and operating conditions. This includes CFD simulations and experimental data comparisons, employing methods aligned with our fundamental research in this area. Furthermore, our work paves the way for integrating these advanced fluid dynamics models into the evolving field of process digitalization, thereby contributing to the development of more efficient, digitally integrated manufacturing processes.

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Wallis. L51614 Slug Frequency in Horizontal Gas-Liquid Flow. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), Februar 1990. http://dx.doi.org/10.55274/r0011058.

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This report responds to A.G.A.s objective of initiating and planning means to create a reliable, mechanistic method of slug frequency prediction. Specific objectives were to: Update the prior review of existing knowledge Identify one or more alternative modelling approaches Recommend additional work if required Examination of empirical correlations for slug frequency shows that they have uncertainties which are large compared with experimental data. A mechanistic approach is sought. Previous mechanistic models have been either incomplete or numerically unstable. Several improvements were made to the Taitel-Dukler model for this process and a new calculation procedure developed using the method of characteristics. It is demonstrated here that this approach alone cannot lead to cyclic slug formation. The processes of wave growth continually wash out downstream without causing new slugs to form upstream. This has led to concentration on the mechanism of slug formation near the inlet to a pipe segment.

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Wang, Yao, Mirela D. Tumbeva und Ashley P. Thrall. Evaluating Reserve Strength of Girder Bridges Due to Bridge Rail Load Shedding. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317308.

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This research experimentally and numerically evaluated the reserve strength of girder bridges due to bridge rail load shedding. The investigation included: (1) performing non-destructive field testing on two steel girder bridges and one prestressed concrete girder bridge, (2) developing validated finite element numerical models, and (3) performing parametric numerical investigations using the validated numerical modeling approach. Measured data indicated that intact, integral, reinforced concrete rails participate in carrying live load. Research results culminated in recommendations to evaluate the reserve strength of girder bridges due to the participation of the rail, as well as recommendations for bridge inspectors for evaluating steel girder bridges subjected to vehicular collision.

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Rose und Luo. L52069 Guided Wave Sizing and Discrimination for SCC Magnetostriction ILI Inspection. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), Januar 2003. http://dx.doi.org/10.55274/r0011179.

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With the goal to be able to inspect a large area of the pipe from a single sensor position, hence the development of what we call guided wave inspection. From one point on the circumference of the pipe, it is therefore proposed to inspect the entire circumferential area of the pipe. This approach leads to inspection efficiency.� Experimental techniques cannot be developed on a trial and error basis. The purpose of this work is therefore to develop a guided wave propagation model and subsequent numerical solutions to assist in the �theoretically driven� sensor design and data acquisition systems for improved nondestructive testing including defect detection, location, and potential classification and sizing analysis in a pipe.

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Ayoul-Guilmard, Q., S. Ganesh, M. Nuñez, R. Tosi, F. Nobile, R. Rossi und C. Soriano. D5.4 Report on MLMC for time dependent problems. Scipedia, 2021. http://dx.doi.org/10.23967/exaqute.2021.2.005.

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In this report, we study the use of Multi-Level Monte Carlo (MLMC) methods for time dependent problems. It was found that the usability of MLMC methods depends strongly on whether or not the underlying time dependent problem is chaotic in nature. Numerical experiments are conducted on both simple problems, as well as fluid flow problems of practical interest to the ExaQUte project, to demonstrate this. For the non-chaotic cases, the hypotheses that enable the use of MLMC methods were found to be satisfied. For the chaotic cases, especially the case of high Reynolds’ number fluid flow, the hypotheses were not satisfied. However, it was found that correlations between the different levels were high enough to merit the use of multi-fidelity or control-variate approaches. It was also noted that MLMC methods could work for chaotic problems if the time window of analysis were chosen to be small enough. Future studies are proposed to examine this possibility.

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Jaros, John A. Experimental Approaches at Linear Colliders. Office of Scientific and Technical Information (OSTI), Februar 2002. http://dx.doi.org/10.2172/799006.

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Jury, William A., und David Russo. Characterization of Field-Scale Solute Transport in Spatially Variable Unsaturated Field Soils. United States Department of Agriculture, Januar 1994. http://dx.doi.org/10.32747/1994.7568772.bard.

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This report describes activity conducted in several lines of research associated with field-scale water and solute processes. A major effort was put forth developing a stochastic continuum analysis for an important class of problems involving flow of reactive and non reactive chemicals under steady unsaturated flow. The field-scale velocity covariance tensor has been derived from local soil properties and their variability, producing a large-scale description of the medium that embodies all of the local variability in a statistical sense. Special cases of anisotropic medium properties not aligned along the flow direction of spatially variable solute sorption were analysed in detail, revealing a dependence of solute spreading on subtle features of the variability of the medium, such as cross-correlations between sorption and conductivity. A novel method was developed and tested for measuring hydraulic conductivity at the scale of observation through the interpretation of a solute transport outflow curve as a stochastic-convective process. This undertaking provided a host of new K(q) relationships for existing solute experiments and also laid the foundation for future work developing a self-consistent description of flow and transport under these conditions. Numerical codes were developed for calculating K(q) functions for a variety of solute pulse outflow shapes, including lognormal, Fickian, Mobile-Immobile water, and bimodal. Testing of this new approach against conventional methodology was mixed, and agreed most closely when the assumptions of the new method were met. We conclude that this procedure offers a valuable alternative to conventional methods of measuring K(q), particularly when the application of the method is at a scale (e.g. and agricultural field) that is large compared to the common scale at which conventional K(q) devices operate. The same problem was approached from a numerical perspective, by studying the feasibility of inverting a solute outflow signal to yield the hydraulic parameters of the medium that housed the experiment. We found that the inverse problem was solvable under certain conditions, depending on the amount of noise in the signal and the degree of heterogeneity in the medium. A realistic three dimensional model of transient water and solute movement in a heterogeneous medium that contains plant roots was developed and tested. The approach taken was to generate a single realization of this complex flow event, and examine the results to see whether features were present that might be overlooked in less sophisticated model efforts. One such feature revealed is transverse dispersion, which is a critically important component in the development of macrodispersion in the longitudinal direction. The lateral mixing that was observed greatly exceeded that predicted from simpler approaches, suggesting that at least part of the important physics of the mixing process is embedded in the complexity of three dimensional flow. Another important finding was the observation that variability can produce a pseudo-kinetic behavior for solute adsorption, even when the local models used are equilibrium.

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Tan, Peng, und Nicholas Sitar. Parallel Level-Set DEM (LS-DEM) Development and Application to the Study of Deformation and Flow of Granular Media. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, März 2023. http://dx.doi.org/10.55461/kmiz5819.

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We present a systematic investigation of computational approaches to the modeling of granular materials. Granular materials are ubiquitous in everyday life and in a variety of engineering and industrial applications. Despite the apparent simplicity of the laws governing particle-scale interactions, predicting the continuum mechanical response of granular materials still poses extraordinary challenges. This is largely due to the complex history dependence resulting from continuous rearrangement of the microstructure of granular material, as well as the mechanical interlocking due to grain morphology and surface roughness. X-Ray Computed Tomography (XRCT) is used to characterize the grain morphology and the fabric of the granular media, naturally deposited sand in this study. The Level-Set based Discrete Element Method (LS-DEM) is then used to bridge the granular behavior gap between the micro and macro scale. The LS-DEM establishes a one-to-one correspondence between granular objects and numerical avatars and captures the details of grain morphology and surface roughness. However, the high-fidelity representation significantly increases the demands on computational resources. To this end a parallel version of LS-DEM is introduced to significantly decrease the computational demands. The code employs a binning algorithm, which reduces the search complexity of contact detection from O(n2) to O(n), and a domain decomposition strategy is used to elicit parallel computing in a memory- and communication-efficient manner. The parallel implementation shows good scalability and efficiency. High fidelity LS avatars obtained from XRCT images of naturally deposited sand are then used to replicate the results of triaxial tests using the new, parallel LS-DEM code. The result show that both micro- and macro-mechanical behavior of natural material is well captured and is consistent with experimental data, confirming experimental observation that the primary source of peak strength of sand is the mechanical interlocking between irregularly shaped grains. Specifically, triaxial test simulations with a flexible membrane produce a very good match to experimentally observed relationships between deviatoric stress and mobilized friction angle for naturally deposited sand. We then explore the viability of modeling dynamic problems with a new formulation of an impulse based LS-DEM. The new formulation is stable, fast, and energy conservative. However, it can be numerically stiff when the assembly has substantial mass differences between particles. We also demonstrate the feasibility of modeling deformable structures in the rigid body framework and propose several enhancements to improve the convergence of collision resolution, including a hybrid time integration scheme to separately handle at rest contacts and dynamic collisions. Finally, we extend the impulse-based LS-DEM to include arbitrarily shaped topographic surfaces and exploit its algorithmic advantages to demonstrate the feasibility of modeling realistic behavior of granular flows. The novel formulation significantly improves performance of dynamic simulations by allowing larger time steps, which is advantageous for observing the full development of physical phenomena such as rock avalanches, which we present as an illustrative example.

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