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Artigos de revistas sobre o assunto "Boundary conditions calibration"
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Herold, Judith, Eric Lemont, Stuart Bettington e Edward Couriel. "CHALLENGES OF BOUNDARY CONDITIONS IN OPEN OCEAN MODELS". Coastal Engineering Proceedings, n.º 36v (28 de dezembro de 2020): 52. http://dx.doi.org/10.9753/icce.v36v.waves.52.
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The development and calibration of coastal numerical models to support engineering design and environmental impact studies is a challenging process and one that requires professional judgement and continual assessment of all aspects of the model makeup. Fundamental to the integrity of the model are appropriate boundary conditions and quality observational data for calibration. Open ocean boundary conditions are typically the most complex and important aspect of a model build. They represent the influence of dynamics occurring beyond the model extent, bridging large-scale dynamics to the small-scale processes in the model. This study discusses the challenges of open ocean boundaries and how we utilised data to achieve an effective model.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/evL7f_17wZg
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Hwang, B.-W., C.-M. Suh e S.-H. Kim. "Finite element analysis of calibration factors for the modified incremental strain method". Journal of Strain Analysis for Engineering Design 38, n.º 1 (1 de janeiro de 2003): 45–51. http://dx.doi.org/10.1243/030932403762671881.
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To modify the incremental strain method used to evaluate non-uniform residual stress, a finite element analysis (FEA) of the reference model used to describe a hole-drilling test was conducted. The calibration factors for the x and y directions were obtained from the analysis and then their differences were compared under various loading conditions. A hole-drilling test using a steel plate as the reference specimen was introduced, and under the pure bending load, strain relaxation was measured at each hole-drilling step to determine the calibration factors. Although the calibration factors in the x and y directions varied with the boundary conditions used in the FEA, their differences were reduced to zero for all depths when the prescribed loads as the boundary conditions in the x and y directions became the same. In addition, it was analytically and experimentally confirmed that the calibration factors did not vary with the direction. Accordingly, by making the calibration factors equal in the x and y directions in the modified equation for the incremental strain method, no singularity is produced in the stress calculations.
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Campbell, D. S., M. Gundappa e T. E. Diller. "Design and Calibration of a Local Heat-Flux Measurement System for Unsteady Flows". Journal of Heat Transfer 111, n.º 2 (1 de maio de 1989): 552–57. http://dx.doi.org/10.1115/1.3250713.
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A local heat–flux measurement system was built, calibrated, and tested for use in unsteady flows. The system was designed to maintain constant-wall-temperature boundary conditions. The measuring element is a thin-film heat flux gage made by sputter-coating gold onto a substrate. A constant-temperature anemometer is used to maintain the thin-film gage at a specified temperature under fluctuating conditions. A separate temperature control system maintains the surrounding boundary at the gage temperature. The system was calibrated for both steady and unsteady flows using a specially designed calibrator for local heat flux gages. The steady calibration was done with predominantly convective heat transfer. The unsteady calibration was achieved by adding oscillating radiant energy to the surface. Consequently, quantitative results can be obtained for both the mean and fluctuating components of the heat transfer. The frequency response was good to over 90 Hz. Sample results are presented of the unsteady heat transfer over a circular cylinder caused by natural vortex shedding at 70 to 80 Hz.
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Monfre, Stephen L., e Steven D. Brown. "Quantitative Fourier-Domain Analysis. Part II: Determination of Boundary Conditions". Applied Spectroscopy 46, n.º 11 (novembro de 1992): 1711–18. http://dx.doi.org/10.1366/0003702924926943.
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A new approach for determining the boundary conditions of a Fourier-domain data set prior to performing quantitative multicomponent analysis has been developed. Processing boundary conditions were determined by calculating the condition number of the calibration matrix which contains the models used to describe the chemical system being studied. Once the boundary conditions for the Fourier-domain data set were determined, the Kalman filter was used to estimate the concentration of individual components in a multicomponent sample. Synthetic data were first analyzed to determine both the feasibility of the data-analysis method and the effect that background variations would have on the concentration estimates. Raw interferograms of multicomponent samples, collected with the use of Fourier transform infrared (FT-IR) spectroscopy, were also analyzed. Validation samples were analyzed to verify the chosen boundary conditions.
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Ahmadi, M. M., P. M. Byrne e R. G. Campanella. "Cone tip resistance in sand: modeling, verification, and applications". Canadian Geotechnical Journal 42, n.º 4 (1 de agosto de 2005): 977–93. http://dx.doi.org/10.1139/t05-030.
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A numerical modeling procedure is presented to evaluate cone tip resistance in sand. The procedure involves a moving boundary simulating cone penetration. The soil is modeled as a MohrCoulomb elasticplastic material with stress-dependent parameters. The procedure is verified by comparing predicted numerical values of cone tip resistance with published experimental measurements from calibration chamber tests. The selected database consists of 59 calibration chamber tests on Ticino sand with different relative densities, overconsolidation ratios, stresses, and boundary conditions. Several applications of the modeling procedure are also presented. The computer program FLAC is used to carry out the analysis.Key words: cone tip resistance, numerical modeling, sand, calibration chamber, Mohr-Coulomb, in situ horizontal stress.
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Sivelle, Vianney, Philippe Renard e David Labat. "Coupling SKS and SWMM to Solve the Inverse Problem Based on Artificial Tracer Tests in Karstic Aquifers". Water 12, n.º 4 (16 de abril de 2020): 1139. http://dx.doi.org/10.3390/w12041139.
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Artificial tracer tests constitute one of the most powerful tools to investigate solute transport in conduit-dominated karstic aquifers. One can retrieve information about the internal structure of the aquifer directly by a careful analysis of the residence time distribution (RTD). Moreover, recent studies have shown the strong dependence of solute transport in karstic aquifers on boundary conditions. Information from artificial tracer tests leads us to propose a hypothesis about the internal structure of the aquifers and the effect of the boundary conditions (mainly high or low water level). So, a multi-tracer test calibration of a model appeared to be more consistent in identifying the effects of changes to the boundary conditions and to take into consideration their effects on solute transport. In this study, we proposed to run the inverse problem based on artificial tracer tests with a numerical procedure composed of the following three main steps: (1) conduit network geometries were simulated using a pseudo-genetic algorithm; (2) the hypothesis about boundary conditions was imposed in the simulated conduit networks; and (3) flow and solute transport were simulated. Then, using a trial-and-error procedure, the simulated RTDs were compared to the observed RTD on a large range of simulations, allowing identification of the conduit geometries and boundary conditions that better honor the field data. This constitutes a new approach to better constrain inverse problems using a multi-tracer test calibration including transient flow.
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Kacem, Ahmed, Hervé Laurent e Sandrine Thuillier. "Influence of experimental boundary conditions on the calibration of a ductile fracture criterion". Engineering Fracture Mechanics 248 (maio de 2021): 107686. http://dx.doi.org/10.1016/j.engfracmech.2021.107686.
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Baldi, Antonio. "Far-Field Boundary Conditions for Calculation of Hole-Drilling Residual Stress Calibration Coefficients". Experimental Mechanics 57, n.º 4 (7 de novembro de 2016): 659–64. http://dx.doi.org/10.1007/s11340-016-0235-1.
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Han, Liya, Long Yu e Xusheng Zhu. "A Novel Method for Pose and Position Calibration of Laser Displacement Sensors". Sensors 23, n.º 4 (4 de fevereiro de 2023): 1762. http://dx.doi.org/10.3390/s23041762.
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Laser displacement sensors are widely used in the aviation industry for the purpose of surface normal measurements. The measurement of a surface normal depends on prior knowledge of the poses and positions of the sensors, which are obtained through calibration. This paper introduces a new parameter to the traditional calibration procedure, to reduce the calibration error, and explores the factors affecting calibration using the Monte Carlo method. In the experiment, the normal measurement error of the probe consisted of four sensors after calibration was less than 0.1∘, which satisfied the established requirements. This paper indicates the boundary conditions for a successful calibration and validates the proposed method, which provides a new method for the pose and position calibration of laser displacement sensors and other similar sensors.
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FURSENKO, Antanas. "Precizinių rastrų formavimo sistemos juostos poslinkio matavimo junginio skaičiuojamieji tyrimai / Analytical research of displacement measuring unit of the precise raster-forming systems". Mokslas - Lietuvos ateitis 9, n.º 6 (29 de dezembro de 2017): 597–601. http://dx.doi.org/10.3846/mla.2017.1092.
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The precision raster-forming systems creation and development must be based on research in the specific work environment. In not ideal metrological conditions the precision raster-forming system allows to achieve high accuracy of the calibration, when used dynamic calibration method.The paper analyzes the possibility of analytical modeling of one main part (steel tape displacement measuring unit) of precise raster forming systems. In the work, a linear mechanical model of steel tape was applied to the load. The work described the equation, which describes the steel tape deformation model under loads with boundary conditions.
Teses / dissertações sobre o assunto "Boundary conditions calibration"
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Niraula, Rewati. "Understanding the Hydrological Response of Changed Environmental Boundary Conditions in Semi-Arid Regions: Role of Model Choice and Model Calibration". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/594961.
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Arid and semi-arid basins in the Western United States (US) have been significantly impacted by human alterations to the water cycle and are among the most susceptible to water stress from urbanization and climate change. The climate of the Western US is projected to change in response to rising greenhouse gas concentrations. Combined with land use/land cover (LULC) change, it can influence both surface and groundwater resources, both of which are a significant source of water in the US. Responding to this challenge requires an improved understanding of how we are vulnerable and the development of strategies for managing future risk. In this dissertation, I explored how hydrology of semi-arid regions responds to LULC and climate change and how hydrologic projections are influenced by the choice and calibration of models. The three main questions I addressed with this dissertation are: 1. Is it important to calibrate models for forecasting absolute/relative changes in streamflow from LULC and climate changes? 2. Do LSMs make reasonable estimates of groundwater recharge in the western US? 3. How might recharge change under projected climate change in the western US? Results from this study suggested that it is important to calibrate the model spatially to analyze the effect of LULC change but not as important for analyzing the relative change in streamflow due to climate change. Our results also highlighted that LSMs have the potential to capture the spatial and temporal patterns as well as seasonality of recharge at large scales. Therefore, LSMs (specifically VIC and Noah) can be used as a tool for estimating current and future recharge in data limited regions. Average annual recharge is projected to increase in about 62% of the region and decrease in about 38% of the western US in future and varies significantly based on location (-50% - +94 for near future and -90% to >100% for far future). Recharge is expected to decrease significantly (-13%) in the South region in the far future. The Northern Rockies region is expected to get more recharge in both in the near (+5.1%) and far (+9.0%) future. Overall, this study suggested that land use/land cover (LULC) change and climate change significantly impacts hydrology in semi-arid regions. Model choice and model calibrations also influence the hydrological predictions. Hydrological projections from models have associated uncertainty, but still provide valuable information for water managers with long term water management planning.
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McElroy, Mark Allen. "A Procedure for Generating Finite Element Models (FEM) of Abdominal Aortic Aneurysms with Fluid Boundary Conditions Derived from Magnetic Resonance Imaging (MRI) Velocimetry". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1284670607.
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Villanueva, Lucas. "Développement d’outils d’assimilation de données pour l’estimation augmentée d’écoulements internes". Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2024. http://www.theses.fr/2024ESMA0019.
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Dans ce travail de thèse, des outils d’assimilation de données sont utilisés pour augmenter les performances de solveurs de mécanique des fluides dédiés à la simulation des grandes échelles. L’objectif est d’améliorer la prédiction et l’étude d’évènements marginaux nuisibles à l’intégrité des systèmes physiques. Bien que difficile à caractériser et à modéliser, la compréhension détaillée de ces phénomènes physiques complexes est essentielle pour le développement d’applications plus durables. Ces objectifs s’intègrent aux activités de recherche du projet ANR ALEKCIA dans lequel ce travail de thèse s’inscrit. Plus précisément, il s’agit de répondre au besoin de couplage de calculs de mécanique des fluides numérique avec un algorithme d’assimilation de données séquentiel. L’outil CONES (Coupling OpenFOAM with Numerical EnvironmentS),qui a été développé, permet d’y apporter une réponse en s’appuyant sur le logiciel OpenFOAM et le filtre de Kalman d’ensemble. Ce dernier permet à la fois le calibrage des paramètres physiques de la simulation numérique ainsi que l’inférence de champs physiques tels que le champ de vitesse. CONES est mis à contribution pour l’inférence de trois cas d’étude à la complexité grandissante. Le premier optimise les coefficients de fermeture de modèles de turbulence de type RANS pour un écoulement incompressible via l’assimilation de données expérimentales. La calibration de ces paramètres entraîne notamment une amélioration topologique des structures de recirculation de la géométrie. Le cas démontre également l’importance de la qualité des informations de sources hétérogènes observées plutôt que leur quantité. Dans une deuxième étude, la simulation des grandes échelles est utilisée pour fournir une prédiction des caractéristiques tridimensionnelles instationnaires d’un écoulement incompressible turbulent en canal. Outre l’optimisation du modèle Smagorinsky, le champ de vitesse est partiellement synchronisé avec les données observées pour favoriser la reconstruction des structures instationnaires. L’influence de certains hyper-paramètres tels que l’inflation est mise en lumière. Enfin, une variante de l’algorithme de Kalman, le filtre de Kalman d’ensemble hyper-localisé, est développée pour le dernier cas d’étude. Cette méthode permet notamment une diminution du coût de calcul. Elle est utilisée pour l’inférence d’une LES de l’écoulement compressible d’une géométrie simplifiée de moteur. La condition d’entrée de référence pulsée est correctement calibrée et le champ de vitesse est localement synchronisé sur les simulations inférées. La correction apportée par l’algorithme montre également une amélioration de la répartition énergétique de la région inférée en adéquation avec la répartition de référence. En conclusion, le potentiel du filtre de Kalman d’ensemble pour la calibration de paramètres physiques et la reconstruction de structures locales grâce à l’observation de données haute-fidélité d’un système réel a été démontré. Ceci permettrait l’étude d’évènements extrêmes pouvant nuire à l’intégrité du système physique grâce à la simulation numérique augmentée de ces phénomènesIn this thesis, data assimilation tools are used to increase the performance of fluid mechanics solvers dedicated to large eddy simulations. The aim is to improve the prediction and study of marginal events harmful to the integrity of physical systems. Although difficult to characterize and model, a detailed understanding of these complex physical phenomena is essential for the development of more sustainable applications. These objectives are in line with the research activities of the ANR ALEKCIA project, of which this thesis is a part. More specifically, the aim is to meet the need to couple numerical fluid mechanics calculations with a sequential data assimilation algorithm. CONES (Coupling OpenFOAM with Numerical EnvironmentS) tool has been developed to provide an answer to this need by using the OpenFOAM software and the ensemble Kalman filter. The latter can be used both to calibrate the physical parameters of the numerical simulation and to infer physical fields, such as the velocity field. CONES is used to infer three case studies of increasing complexity. The first optimizes the closure coefficients of RANS-type turbulence models for an incompressible flow by assimilating experimental data. The calibration of these parameters leads in particular to a topological improvement in the recirculation structures of the geometry. The case also demonstrates the importance of the quality of the heterogeneous source of information observed rather than its quantity. In a second study, large eddy simulation is used to provide a prediction of the unsteady three-dimensional characteristics of a turbulent incompressible flow in a channel. In addition to optimizing the Smagorinsky model, the velocity field is partially synchronized with the observed data to facilitate the reconstruction of the unsteady structures. The influence of hyper parameters such as inflation is highlighted. Finally, a variant of the Kalman algorithm, the hyper-localized ensemble Kalman filter, is developed for the last case study. In particular, this method reduces the computational cost.It is used to infer a LES of the compressible flow of a simplified engine geometry. The pulsed reference input condition is correctly calibrated and the velocity field of the inferred simulations is locally synchronized. The correction provided by the algorithm also shows an improvement in the energy distribution of the inferred region in line with the reference distribution. In conclusion, the potential of the ensemble Kalman filter for calibrating physical parameters and reconstructing local structures by observing high-fidelity data from the real system has been demonstrated. This could enable the study of extreme events that could damage the integrity of the physical system, thanks to the augmented numerical simulation of these phenomena
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Moshfegh, Abouzar. "Dissipative Particle Dynamics Simulation of Suspensions Rheology, and Electroosmotic Flow in Nanochannels". Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14367.
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The dissipative particle dynamics (DPD) method is developed using innovative numerical techniques and extensively examined in the contexts of rheology and electroosmosis. In Chapters 3-5, it is attempted to classify practical ranges of DPD parameters under a variety of simulation settings, thermostating schemes and shearing methods. Through a calibration process, useful windows of parameters are categorised so that DPD users can model a wide range of rheological systems conveniently with proper temperature control and equilibrium statistics. DPD was found to perform poorly under certain dissipation rates and shear rates when sheared via original Lees-Edwards boundary condition. Hence, a modified version of this shearing method is shown to be an effective remedy to improve the hydrodynamics and thermal stability of sheared DPD systems. These achievements shed light on unclear correlations between input parameters and simulation outputs, and relatively rectifies the lack of predictability embedded in DPD method. In Chapter 6, it is shown that plain DPD is inherently a flexible numerical tool to reproduce experimental behaviour of dilute to dense suspensions. This is achieved via a simple calibration of parameters without unnecessary and computationally intensive modifications to DPD underlying formulas. In Chapter 7, contrary to existing DPD modellings of electroosmotic flow (EOF), soft-core electrostatic interactions are treated fully explicitly by inclusion of charge clouds around DPD soft beads and adopting the corrected Ewald sum method (EW3DC). The developed DPD platform is then calibrated to match the results of molecular dynamics, and reproduce experimental trends. A new system of unit conversion between DPD reduced units and SI units is introduced, which is also useful in other electrokinetic applications. The coarse-graining degree of beads is set to unity to challenge DPD performance in the smallest possible length scale, i.e. in a nanochannel sized at 3.8 nm.
Capítulos de livros sobre o assunto "Boundary conditions calibration"
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Kleinfeller, Nikolai, Christopher M. Gehb, Maximilian Schaeffner, Christian Adams e Tobias Melz. "Assessment of Model Uncertainty in the Prediction of the Vibroacoustic Behavior of a Rectangular Plate by Means of Bayesian Inference". In Lecture Notes in Mechanical Engineering, 264–77. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77256-7_21.
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AbstractDesigning the vibroacoustic properties of thin-walled structures is of particularly high practical relevance in the design of vehicle structures. The vibroacoustic properties of thin-walled structures, e.g., vehicle bodies, are usually designed using finite element models. Additional development effort, e.g., experimental tests, arises if the quality of the model predictions are limited due to inherent model uncertainty. Model uncertainty of finite element models usually occurs in the modeling process due to simplifications of the geometry or boundary conditions. The latter highly affect the vibroacoustic properties of a thin-walled structure. The stiffness of the boundary condition is often assumed to be infinite or zero in the finite element model, which can lead to a discrepancy between the measured and the calculated vibroacoustic behavior. This paper compares two different boundary condition assumptions for the finite element (FE) model of a simply supported rectangular plate in their capability to predict the vibroacoustic behavior. The two different boundary conditions are of increasing complexity in assuming the stiffness. In a first step, a probabilistic model parameter calibration via Bayesian inference for the boundary conditions related parameters for the two FE models is performed. For this purpose, a test stand for simply supported rectangular plates is set up and the experimental data is obtained by measuring the vibrations of the test specimen by means of scanning laser Doppler vibrometry. In a second step, the model uncertainty of the two finite element models is identified. For this purpose, the prediction error of the vibroacoustic behavior is calculated. The prediction error describes the discrepancy between the experimental and the numerical data. Based on the distribution of the prediction error, which is determined from the results of the probabilistic model calibration, the model uncertainty is assessed and the model, which most adequately predicts the vibroacoustic behavior, is identified.
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McDougall, Kristin. "Global biotic events evident in the Paleogene marine strata of the eastern San Francisco Bay area, California". In Regional Geology of Mount Diablo, California: Its Tectonic Evolution on the North America Plate Boundary. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.1217(12).
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ABSTRACT Paleogene marine strata in the eastern San Francisco Bay area are exposed in discontinuous outcrops in the various tectonic blocks. Although there are many missing intervals, the strata were previously thought to span most of the Paleocene and Eocene. Revision of biochronology and calibration to the international time scale as well as to the global oxygen isotope curve and sea-level curves indicate that the strata are latest Paleocene through middle Eocene in age and contain faunal changes that are linked to the overall global climate trends and hyperthermals of that time. The Paleocene-Eocene thermal maximum, third Eocene thermal maximum, early Eocene climatic optimum, and middle Eocene climatic optimum are all identified in the eastern San Francisco Bay marine strata. The dominance of smoothly finished, dissolution-resistant agglutinated benthic foraminiferal species corresponds with a rapid shoaling and rapid deepening (overcorrection) of the calcium compensation depth associated with the Paleocene-Eocene thermal maximum. The benthic foraminiferal extinction event was a dramatic turnover of benthic foraminiferal species that occurred shortly after the onset of the Paleocene-Eocene thermal maximum. Opportunistic species such as Bulimina, which indicate environmental stress and lower oxygen conditions, are commonly associated with the Paleocene-Eocene thermal maximum. Environmental changes similar to those observed during the Paleocene-Eocene thermal maximum also characterize the third Eocene thermal maximum, based on the agglutinated and opportunistic species. The early Eocene climatic optimum is noted by the presence of foraminiferal assemblages that indicate a stable, warmer water mass, abundant food, and an influx of terrigenous material. The onset and end of the middle Eocene climatic optimum are recognized by the dominance of siliceous microfossils. This research updates the age and environmental interpretations of the Paleogene formations occurring in the vicinity of Mount Diablo, eastern San Francisco Bay area. The revised interpretations, which are based on foraminifers and calcareous nannoplankton, make it possible to identify various global climatic and biotic events.
Trabalhos de conferências sobre o assunto "Boundary conditions calibration"
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Cheng, Hwai-Ping (Pearce), Earl V. Edris e David R. Richards. "Investigating the Application of Channel Boundary Conditions for Model Calibration and Validation". In World Environmental and Water Resources Congress 2007. Reston, VA: American Society of Civil Engineers, 2007. http://dx.doi.org/10.1061/40927(243)272.
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Rumiantsev, Andrej, Ralf Doerner e Edward M. Godshalk. "The influence of calibration substrate boundary conditions on CPW characteristics and calibration accuracy at mm-wave frequencies". In 2008 72nd ARFTG Microwave Measurement Symposium. IEEE, 2008. http://dx.doi.org/10.1109/arftg.2008.4804293.
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Cong, Tenglong, Minjun Peng e Xiang Zhang. "Prediction of Subcooled Boiling With Uncertainties From Boundary Conditions and Interaction Models". In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81101.
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Subcooled boiling has been investigated by using the RPI wall boiling models in the last two decades. High accuracy of such models has been achieved by improving the submodels for interphase actions or tuning the model parameters. However, the reliabilities of the models are still suspicious due to the limited model validation and the experimental data based model calibration. The applicability of calibrated model parameters in the new experiment data can not be assured. The effects of model parameters need to be calibrated were treated as the uncertainties of these parameters. The critical parameters that dominate the prediction of subcooled boiling were selected by using the hierarchy analysis. After that, the input samples for uncertainty analysis were obtained by an efficient Monte-Carlo sampling technology — Latin Hypercube Sampling based on the hypothetic normal distribution. Then, the samples were transferred into the FLUENT code for CFD calculations. Results from CFD code were extracted for statistical analysis. Besides, the uncertainties from boundary conditions were also analyzed to quantify the effects of experimental uncertainties. The dependency of the predicted subcooling parameters and the input parameters can be obtained. A PIRT table can be drawn from the generated correlation coefficients between inputs and outputs to quantify the importance of model parameters on subcooled boiling.
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Zhang, Huiyan, Hualei Li, Mengyu Li, Lei Shi e Kangyao Deng. "Study on the Regulation Boundary for Two-Stage Turbocharging System at Different Altitudes". In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63923.
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Regulated two-stage (RTS) turbocharging system is an effective way to enhance power density and reduce pollutant of internal combustion engine for increasingly stringent demands of fuel consumption and emission regulation. Due to achieving high boost pressure with great system efficiency and controllable characteristic in wide working range, the RTS turbocharging system improves output power at low speed condition and reduces pumping loss at high speed condition. Composing of two turbochargers and control valves, the RTS turbocharging system is matched with engine at a design point and regulated by adjusting control valves to meet the engine requirement of intake pressure and flow at other working conditions. Calibration of the control valves under all operating conditions by plentiful experiments is significant for turbocharging system, particularly that matched with diesel engine for vehicle. Moreover, when an automobile run on the plateau, the intake air flow will decrease and combustion in cylinder will deteriorate obviously. Compared with other turbocharging system, two-stage turbocharging system is more suitable to the offset power loss of engine. Regulating boost system under different operation conditions draws more attention to engine performance recovery so that the workload of calibration raises rapidly in consideration of altitude factor. Though much work has been done in calibration at various altitudes, there are few, if any, discussion on open-closed boundary of control valves to simplify the calibration process. In this paper, it aims to present a regulation boundary model of control valve at different altitudes to guide the calibration and a series of experiments for RTS system can be saved. Firstly, a thermodynamics analysis of the RTS turbocharging system is conducted and typical regulation methods are compared in terms of the adjustment capacity and efficiency characteristics of turbocharging system, which indicates that high-stage turbine bypass is the optimum regulation method. Then, a regulation boundary model for the RTS turbocharging system at different altitudes is deduced, according to the relation of equivalent turbine area and engine operating condition. The regulation boundaries of different altitudes are obtained by iterative computation of the model, and the whole working mode of the RTS system is divided into a fully closed area and a regulated area. Experiments are carried out to verify the regulation boundary model at sea level condition. Brake torque, efficiency of the RTS system and temperature before high-stage turbine are primary parameters for verification in this article. The maximum error shows up with a value of 3.65% brake torque at 2200rpm. While a one-dimensional simulation model is built up to validate the regulation boundary model of the plateau. All the errors are smaller than 3% at various altitudes. It results that model is accurate enough to predict the regulation boundary of the RTS system. By the calculation of regulation boundary model, the brake torque at regulation boundary will decrease if the engine speeds up. It also manifests that fully closed area will argument if the automobile climbs up to high operating altitude, especially under high speed condition.
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Wright, Stephen, Avinash Ravikumar, Laura Redmond, Chris McMahan, Benjamin Lawler, Matthew P. Castanier, Eric Gingrich e Michael Tess. "Benchmarking of Neural Network Methodologies for Piston Thermal Model Calibration". In WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2024. http://dx.doi.org/10.4271/2024-01-2598.
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<div class="section abstract"><div class="htmlview paragraph">Design of internal combustion (IC) engine pistons is dependent on accurate prediction of the temperature field in the component. Experimental temperature measurements can be taken but are costly and typically limited to a few select locations. High-fidelity computer simulations can be used to predict the temperature at any number of locations within the model, but the models must be calibrated for the predictions to be accurate. The largest barrier to calibration of piston thermal models is estimating the backside boundary conditions, as there is not much literature available for these boundary conditions. Bayesian model calibration is a common choice for model calibration in literature, but little research is available applying this method to piston thermal models. Neural networks have been shown in literature to be effective for calibration of piston thermal models. In this work, Bayesian model calibration will be compared to two neural network-based calibration methodologies for piston thermal models. The models were compared for both computation time and error across three different data densities. Each data set represents an increasing density of steady-state temperature measurement locations. The results show that the error between the methods is largely consistent across the different data densities, with each model having similar error to the others at each calibration case. On the other hand, computation time highlights the advantage of the neural network methodologies over the Bayesian methodology. At the lowest data density, the Bayesian model calibration methodology had the fastest computation time but only by a few minutes. As the data density increased, the Bayesian model calibration method became hours slower than the Neural network methods, up to 4673.3% slower at the highest data density. Both neural networks-based approaches and the Bayesian model calibration methodology are effective at calibrating at low data densities but for higher data densities, the Bayesian model calibration becomes too computationally expensive.</div></div>
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Pawar, Jasjit, Sean Biggs e R. P. Jones. "Sensitivity of System Boundary Conditions on the Migration of Low Frequency Modes Controlling Longitudinal Vehicle Response". In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34628.
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Vehicle driveability is increasingly used as a key measure in media evaluations, and is refined aggressively to differentiate and position the product within its market segment. This is a highly complex system level issue, and encompasses the non-linear interactions between the driveline, suspension and powerunit mounting hardware. The driveability character of the vehicle has typically been tuned through calibration in the later stages of development. Through the use of physical prototypes, such activities have typically been performed on the basis of subjective assessments, to achieve a balanced compromise with other vehicle attributes such as ride, handling and refinement. This paper introduces a model-based approach to facilitate design and detailed analysis early in the product development process, thereby reducing reliance on physical prototypes and the need to implement late design changes. A detailed non-linear mathematical model has therefore been developed in order to characterise the low frequency, longitudinal behaviour of a prototype, four-wheel drive vehicle both in the time and frequency domains. In conjunction with full vehicle test measurements, the analytical model has been validated and then used to investigate a low frequency, fore-aft vehicle oscillation issue that was identified specifically during part throttle pullaway events in cold climate testing.
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Beardsmore, D. W., H. Teng e Michael Martin. "On the Expected Errors in Calibration of the Beremin Cleavage Model Parameters". In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26559.
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We present the detailed results of a series of Monte Carlo simulations of the Gao and Dodds calibration procedure that was carried out to determine the likely size in the errors in the Beremin cleavage model parameter estimates that might be expected for fracture toughness data sets of various sizes. The calibration process was carried out a large number of times using different sample sizes, and mean values and standard errors in the parameter estimates were determined. Modified boundary layer finite element models were used to represent high and low constraint conditions (as in the fracture tests) as well as the SSY condition. The “experimental” Jc values were obtained numerically by random sampling of a Beremin distribution function with known values of the true parameters. A number of cautionary remarks in the application of the calibration method are made.
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Melekidis, Stefanos, Maximilian Elfner e Hans-Jörg Bauer. "Towards Quantitative Wall Shear Stress Measurements: Calibration of Liquid Crystals". In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14381.
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Abstract The wall shear stress distribution on an aerodynamically loaded component is of both practical and fundamental importance. Significant examples are the improvement of the performance of a vehicle, e.g. drag reduction, and more basic problems, such as the characterization of surface flows, e.g. with respect to flow control. The liquid crystal technique represents a promising diagnostics for measuring wall shear stress magnitude and orientation. In contrast to most other techniques, the direct measurement of two-dimensional wall shear stress distributions is straightforward. In order to establish quantitative measurements of wall shear stress using the liquid crystal technique, an in-depth understanding of the influencing parameters is required. For their investigation, a novel generic flat plate test section was designed. The experiments are performed in such a way that a turbulent boundary layer is triggered at a corresponding Reynolds number within the test section. Due to the generic test case, precise and well-known flow boundary conditions can be established, which in turn are validated by probe measurements. Velocity and temperature profiles are recorded with high spatial resolution using a miniaturized combined Pitot-thermocouple probe. Furthermore, the operational range of the new test rig is presented. Preliminary wall shear stress measurements confirm the well-defined flow conditions in the test section and the potential of the measurement technique.
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Saunders, K., S. Alizadeh, L. V. Lewis e J. Provins. "The Use of CFD to Generate Heat Transfer Boundary Conditions for a Rotor-Stator Cavity in a Compressor Drum Thermal Model". In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-28333.
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In an engine design process, thermo-mechanical analyses of compressor drums and casings are undertaken, to predict component temperatures and displacements, which are ultimately used for material selection, blade clearance control and lifing of components. The thermal boundary conditions are sourced from a small number of standard flow field and heat transfer solutions, leading to a reliance on engine thermocouple tests to provide calibration factors on the boundary conditions, which with changes in inlet flows and cavity geometry from the tested arrangements are unproven, limiting the ability to readacross the test information into new designs. Given that the thermal boundary conditions in compressor drum and casing components are largely driven by complex flow physics, in the absence of suitable test information, CFD methods can be used to provide boundary specification of the thermo-mechanical problem, incorporating the complex physics involved. Without the insight of the flow field solution in complex flow regions, specification of the boundary conditions is rather subjective and mostly based on intuition. This study shows the use of CFD to provide the boundary conditions for the rotor-stator cavity at the front of an IP compressor drum. The CFD is run adiabatically and through a set of unit heat transfer cases on separate sections of the cavity wall, at key points in the flight cycle. The analyses provide appropriately characterized thermal boundary conditions (specifically heat transfer coefficients and adiabatic wall temperatures) that are transferred into the thermo-mechanical model, which can then be run through a wide range of cycles without the need for further CFD calculations.
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Schmid, Alexander, Angelo Pasquale, Christian Ellersdorfer, Marco Raffler, Victor Champaney, Mustapha Ziane, Francisco Chinesta e Florian Feist. "Mechanical Characterization of Li-Ion Cells and the Calibration of Numerical Models Using Proper Generalized Decomposition". In ASME 2023 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/imece2023-113228.
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Abstract The behavior of lithium-ion cells under mechanical load is determined by both experiments and simulations. Extensive experimental data are required for the calibration and validation of complex numerical models. The possible experiments may differ in dimension (component, cell, cell stack and module) and in boundary conditions during the experiments (e.g. loading rate, sample condition). This study covers two aspects: The characterization and the modeling: First an overview on innovative experimental procedures is given. Second, it is shown how to quickly calibrate a macroscopic cell model against the experimental data. The calibration effort increases strongly with the number of calibration parameters as with the number of test configurations against which the model is calibrated. A new calibration procedure is presented to overcome this hurdle: First, a meta-model is created, covering the calibration parameters and calibration load cases, employing Proper Generalized Decomposition. Once the meta-model is adequately trained, the optimization of calibration parameters is conducted in real-time employing the meta-model. So a macroscopic cell model can be calibrated very quickly against a given set of experimental data sets. This is important because there are constant improvements and changes to the batteries in terms of materials, dimensions and structure.