Littérature scientifique sur le sujet « Velocity and Density 3D models »
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Articles de revues sur le sujet "Velocity and Density 3D models"
1
Guo, Peng, et George A. McMechan. « Sensitivity of 3D 3C synthetic seismograms to anisotropic attenuation and velocity in reservoir models ». GEOPHYSICS 82, no 2 (1 mars 2017) : T79—T95. http://dx.doi.org/10.1190/geo2016-0321.1.
Texte intégralRésumé :
Anisotropic attenuation in fluid-saturated reservoirs with high fracture density may be diagnostic for reservoir characterization. Wave-induced mesoscale fluid flow is considered to be the major cause of intrinsic attenuation at exploration seismic frequencies. We perform tests of the sensitivity, of anisotropic attenuation and velocity, to reservoir properties in fractured HTI media based on the mesoscale fluid flow attenuation mechanism. The viscoelastic T-matrix, a unified effective medium theory of global and local fluid flow mechanisms, is used to compute frequency-dependent anisotropic attenuation and velocity for ranges of reservoir properties, including fracture density, orientation, fracture aspect ratio, fluid type, and permeability. The 3D 3C staggered-grid finite-difference anisotropic viscoelastic modeling with a Crank-Nicolson scheme is used to generate seismograms using the frequency-dependent velocity and attenuation computed by the viscoelastic T-matrix. A standard linear solid model relates the stress and strain relaxation times to the frequency-dependent attenuation, in the relaxation mechanism equation. The seismic signatures resulting from changing viscoelastic reservoir properties are easily visible. Velocity becomes more sensitive to the fracture aspect ratio when considering fluid flow compared with when the fluid is isolated. Anisotropy of attenuation affects 3C viscoelastic seismic data more strongly than velocity anisotropy does. Analysis of the influence of reservoir properties, on seismic properties in mesoscale fluid-saturated fractured reservoirs with high fracture density, suggests that anisotropic attenuation is a potential tool for reservoir characterization.
2
Huang, Long, Robert R. Stewart, Nikolay Dyaur et Jose Baez-Franceschi. « 3D-printed rock models : Elastic properties and the effects of penny-shaped inclusions with fluid substitution ». GEOPHYSICS 81, no 6 (novembre 2016) : D669—D677. http://dx.doi.org/10.1190/geo2015-0655.1.
Texte intégralRésumé :
3D printing techniques (additive manufacturing) using different materials and structures provide opportunities to understand porous or fractured materials and fluid effects on their elastic properties. We used a 3D printer (Stratasys Dimension SST 768) to print one “solid” cube model and another with penny-shaped inclusions. The 3D printing process builds materials, layer by layer, producing a slight “bedding” plane, somewhat similar to a sedimentary process. We used ultrasonic transducers (500 kHz) to measure the P- and S-wave velocities. The input printing material was thermoplastic with a density of [Formula: see text], P-wave velocity of [Formula: see text], and S-wave velocity of [Formula: see text]. The solid cube had a porosity of approximately 6% and a density of [Formula: see text]. Its P-wave velocity was [Formula: see text] in the bedding direction and [Formula: see text] normal to bedding. We observed S-wave splitting with fast and slow velocities of 879 and [Formula: see text], respectively. Quality factors for P- and S-waves were estimated using the spectral-ratio method with [Formula: see text] ranging from 15 to 17 and [Formula: see text] from 24 to 27. By introducing penny-shaped inclusions along the bedding direction in a 3D printed cube, we created a more porous volume with density of [Formula: see text] and porosity of 24%. The inclusions significantly decreased the P-wave velocity to 1706 and [Formula: see text] parallel and normal to the bedding plane. The fast and slow S-wave velocities also decreased to 812 and [Formula: see text]. A fluid substitution experiment, performed with water, increased (20%–46%) P-wave velocities and decreased (9%–10%) S-wave velocities. Theoretical predictions using Schoenberg’s linear-slip theory and Hudson’s penny-shaped theory were calculated, and we found that both theories matched the measurements closely (within 5%). The 3D printed material has interesting and definable properties and is an exciting new material for understanding wave propagation, rock properties, and fluid effects.
3
Ishikawa, Mayra, Wendy Gonzalez, Orides Golyjeswski, Gabriela Sales, J. Andreza Rigotti, Tobias Bleninger, Michael Mannich et Andreas Lorke. « Effects of dimensionality on the performance of hydrodynamic models for stratified lakes and reservoirs ». Geoscientific Model Development 15, no 5 (16 mars 2022) : 2197–220. http://dx.doi.org/10.5194/gmd-15-2197-2022.
Texte intégralRésumé :
Abstract. Numerical models are an important tool for simulating temperature, hydrodynamics, and water quality in lakes and reservoirs. Existing models differ in dimensionality by considering spatial variations of simulated parameters (e.g., flow velocity and water temperature) in one (1D), two (2D) or three (3D) spatial dimensions. The different approaches are based on different levels of simplification in the description of hydrodynamic processes and result in different demands on computational power. The aim of this study is to compare three models with different dimensionalities and to analyze differences between model results in relation to model simplifications. We analyze simulations of thermal stratification, flow velocity and substance transport by density currents in a medium-sized drinking-water reservoir in the subtropical zone, using three widely used open-source models: GLM (1D), CE-QUAL-W2 (2D) and Delft3D (3D). The models were operated with identical initial and boundary conditions over a 1-year period. Their performance was assessed by comparing model results with measurements of temperature, flow velocity and turbulence. Our results show that all models were capable of simulating the seasonal changes in water temperature and stratification. Flow velocities, only available for the 2D and 3D approaches, were more challenging to reproduce, but 3D simulations showed closer agreement with observations. With increasing dimensionality, the quality of the simulations also increased in terms of error, correlation and variance. None of the models provided good agreement with observations in terms of mixed layer depth, which also affects the spreading of inflowing water as density currents and the results of water quality models that build on outputs of the hydrodynamic models.
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Kurapati, Sushma, Jayaram N. Chengalur, Peter Kamphuis et Simon Pustilnik. « Mass models of gas-rich void dwarf galaxies ». Monthly Notices of the Royal Astronomical Society 491, no 4 (3 décembre 2019) : 4993–5014. http://dx.doi.org/10.1093/mnras/stz3334.
Texte intégralRésumé :
ABSTRACT We construct mass models of eight gas rich dwarf galaxies that lie in the Lynx–Cancer void. From NFW fits to the dark matter halo profile, we find that the concentration parameters of haloes of void dwarf galaxies are similar to those of dwarf galaxies in normal density regions. We also measure the slope of the central dark matter density profiles, obtained by converting the rotation curves derived using 3D (fat) and 2D (ROTCUR) tilted ring fitting routines, into mass densities. We find that the average slope (α = −1.39 ± 0.19), obtained from 3D fitting is consistent with that expected from an NFW profile. On the other hand, the average slope measured using the 2D approach is closer to what would be expected for an isothermal profile. This suggests that systematic effects in velocity field analysis have a significant effect on the slope of the central dark matter density profiles. Given the modest number of galaxies we use for our analysis, it is important to check these results using a larger sample.
5
KARTOON, D., D. ORON, L. ARAZI et D. SHVARTS. « Three-dimensional multimode Rayleigh–Taylor and Richtmyer–Meshkov instabilities at all density ratios ». Laser and Particle Beams 21, no 3 (juillet 2003) : 327–34. http://dx.doi.org/10.1017/s0263034603213069.
Texte intégralRésumé :
The three-dimensional (3D) turbulent mixing zone (TMZ) evolution under Rayleigh–Taylor and Richtmyer–Meshkov conditions was studied using two approaches. First, an extensive numerical study was made, investigating the growth of a random 3D perturbation in a wide range of density ratios. Following that, a new 3D statistical model was developed, similar to the previously developed two-dimensional (2D) statistical model, assuming binary interactions between bubbles that are growing at a 3D asymptotic velocity. Confirmation of the theoretical model was gained by detailed comparison of the bubble size distribution to the numerical simulations, enabled by a new analysis scheme that was applied to the 3D simulations. In addition, the results for the growth rate of the 3D bubble front obtained from the theoretical model show very good agreement with both the experimental and the 3D simulation results. A simple 3D drag–buoyancy model is also presented and compared with the results of the simulations and the experiments with good agreement. Its extension to the spike-front evolution, made by assuming the spikes' motion is governed by the single-mode evolution determined by the dominant bubbles, is in good agreement with the experiments and the 3D simulations. The good agreement between the 3D theoretical models, the 3D numerical simulations, and the experimental results, together with the clear differences between the 2D and the 3D results, suggest that the discrepancies between the experiments and the previously developed models are due to geometrical effects.
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Sharov, N. V., L. I. Bakunovich, B. Z. Belashev et M. Y. Nilov. « Velocity structure and density inhomogeneities of the White Sea crust ». Arctic : Ecology and Economy, no 4(40) (décembre 2020) : 43–53. http://dx.doi.org/10.25283/2223-4594-2020-4-43-53.
Texte intégralRésumé :
The study area is the White Sea basin and adjacent territories. The relevance of the work carried out here is determined by active geodynamics, kimberlite magmatism, and prospects for the hydrocarbon search. The authors set the goal to model the velocity structure of the region’s crust using data from instrumental observations and the Integro software package. A comprehensive interpretation of gravimetric, magnetometric, seismic, petrophysical and geological data has been carried out. With the help of 2D models based on the DSZ profiles and digital maps of geophysical fields, refined density structures of local sections of the earth’s crust have been specified. The developed 3D density model gives a general picture of the deep structure of the region’s crust. Within its framework, the spatial positions of the layers of the velocity reference model are determined and their connections with density inhomogeneities and geophysical anomalies are established.
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Sukhinov, A., A. Chistyakov, S. Protsenko et E. Protsenko. « Study of 3D discrete hydrodynamics models using cell filling ». E3S Web of Conferences 224 (2020) : 02016. http://dx.doi.org/10.1051/e3sconf/202022402016.
Texte intégralRésumé :
Modern methods and tools for coastal hydrodynamics modeling indicate the necessity of constructing discrete analogs of models for ones the properties: balance and conservation laws (for mass, flows, impulse), stability, convergence and etc. have been fulfilled. The paper considers a continuous three-dimensional mathematical model of the hydrodynamics of water basins and its discretization. The pressure correction method at variable water medium density was used to solve the problem of hydrodynamics. The considered discrete mathematical models of hydrodynamics take into account the filling of control cells on rectangular grids. This increased the accuracy of the solution in the case of complex geometry by improving the boundary approximation. From the obtained estimates of the components of the velocity vector, it follows that there are no two or more stationary regimes in which all forces are balanced, and the solution to the discrete problem exists and is unique and tends to the solution of the continuous problem upon reaching the stationary regime. Also the balance of the flows for the discrete model has been proved as well as absence of non-conservative dissipative terms.
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Qiu, Ruofan, Rongqian Chen, Chenxiang Zhu et Yancheng You. « A Hermite-based lattice Boltzmann model with artificial viscosity for compressible viscous flows ». International Journal of Modern Physics B 32, no 13 (11 mai 2018) : 1850157. http://dx.doi.org/10.1142/s0217979218501576.
Texte intégralRésumé :
A lattice Boltzmann model on Hermite basis for compressible viscous flows is presented in this paper. The model is developed in the framework of double-distribution-function approach, which has adjustable specific-heat ratio and Prandtl number. It contains a density distribution function for the flow field and a total energy distribution function for the temperature field. The equilibrium distribution function is determined by Hermite expansion, and the D3Q27 and D3Q39 three-dimensional (3D) discrete velocity models are used, in which the discrete velocity model can be replaced easily. Moreover, an artificial viscosity is introduced to enhance the model for capturing shock waves. The model is tested through several cases of compressible flows, including 3D supersonic viscous flows with boundary layer. The effect of artificial viscosity is estimated. Besides, D3Q27 and D3Q39 models are further compared in the present platform.
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Moens, Nicolas, et Levin Hennicker. « The first 3D models of evolved hot star outflows ». Proceedings of the International Astronomical Union 16, S366 (novembre 2020) : 15–20. http://dx.doi.org/10.1017/s1743921322000230.
Texte intégralRésumé :
AbstractThe mechanisms driving mass loss from massive stars in late stages of their evolution is still very much unknown. Stellar evolution models indicate that the last stage before going supernova for many massive stars is the Wolf-Rayet (WR) phase, characterized by a strong, optically thick stellar wind. Stellar models show that these stars exceed the Eddington limit already in deep sub-surface layers around the so-called ‘iron-opacity’ bump, and so should launch a supersonic outflow from there. However, if the outward force does not suffice to accelerate the gas above the local escape speed, the initiated flow will stagnate and start raining down upon the stellar core. In previous, spherically symmetric, WR wind models, this has been circumvented by artificially increasing either clumping or the line force. Here, we present pioneering 3D time-dependent radiation-hydrodynamic simulations of WR winds. In these models, computed without any ad-hoc force enhancement, the stagnated flow leads to co-existing regions of up- and down-flows, which dynamically interact with each other to form a multi-dimensional and complex outflow. These density structures, and the resulting highly non-monotonic velocity field, can have important consequences for mass-loss rates and the interpretation of observed Wolf-Rayet spectra.
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Zhang, Jian, Chi‐Yuen Wang, Yaolin Shi, Yongen Cai, Wu‐Cheng Chi, Douglas Dreger, Win‐Bin Cheng et Yen‐Horng Yuan. « Three‐dimensional crustal structure in central Taiwan from gravity inversion with a parallel genetic algorithm ». GEOPHYSICS 69, no 4 (juillet 2004) : 917–24. http://dx.doi.org/10.1190/1.1778235.
Texte intégralRésumé :
The genetic algorithm method is combined with the finite‐element method for the first time as an alternative method to invert gravity anomaly data for reconstructing the 3D density structure in the subsurface. The method provides a global search in the model space for all acceptable models. The computational efficiency is significantly improved by storing the coefficient matrix and using it in all forward calculations, then by dividing the region of interest into many subregions and applying parallel processing to the subregions. Central Taiwan, a geologically complex region, is used as an example to demonstrate the utility of the method. A crustal block 120 × 150 km2 in area and 34 km in thickness is represented by a finite‐element model of 76 500 cubic elements, each 2 × 2 × 2 km3 in size. An initial density model is reconstructed from the regional 3D tomographic seismic velocity using an empirical relation between velocity and density. The difference between the calculated and the observed gravity anomaly (i.e., the residual anomaly) shows an elongated minimum of large magnitude that extends along the axis of the Taiwan mountain belt. Among the interpretive models tested, the best model shows a crustal root extending to depths of 50 to 60 km beneath the axis of the Western Central and Eastern Central Ranges with a density contrast of 400 or 500 kg/m3 across the Moho. Both predictions appear to be supported by independent seismological and laboratory evidence.
Thèses sur le sujet "Velocity and Density 3D models"
1
Kelly, Annabel. « The crustal velocity and density structure of Northwest Europe : a 3D model and its implications for isostasy ». Thesis, University of Leicester, 2005. http://hdl.handle.net/2381/30458.
Texte intégralRésumé :
A new seismic P-wave velocity model has been constructed for a region of northwest Europe encompassing Britain, Ireland and the surrounding marine sedimentary basins. This model has considerably higher resolution than previously published velocity models for the region and is unique in being quantitatively constrained. The velocity model provides a tool for future work in seismology, allowing crustal correction for teleseismic arrivals recorded in Britain and Ireland, refined local earthquake location and provides a starting model for local and regional seismic tomography. The velocity model has been developed in conjunction with a crustal density model. The new models indicate that: the mean crustal velocity and density are related to the near-surface geology; the near-surface velocity is well correlated with the near-surface geology; there may be a regional trend from high velocity crust near the northwest continental margin to lower velocity crust under continental Europe; there may be a weak trend of increasing density with increasing crustal thickness; and that the crustal structure beneath the sedimentary basin varies from basin to basin. In addition to the geological interpretation, the density model has been used to investigate isostasy in the region using a newly developed method for estimating the elastic thickness of the lithosphere. This approach uses the relationship between the predicted height of topography for local isostatic equilibrium and the true topography to estimate the degree of compensation, which is in turn related to the elastic thickness. However, the results of this investigation are inconsistent across the different wavelengths tested and so the elastic thickness is resolved with less constraint than the range in published values for the region.
2
D'Angelo, Beatrice. « Density and velocity profiles in dark scattering models ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16210/.
Texte intégralRésumé :
Per quanto la cosmologia osservativa odierna sia in una fase di precisione senza precedenti, con i dati CMB, BAO, e Supernovae Ia che mostrano di essere in accordo con l’attuale modello LCDM, i dati Planck sono in tensione con quelli a basso redshift, provenienti ad esempio dal misurazioni di weak lensing, che puntano verso un tasso più basso di crescita delle strutture.
I modelli Dark Scattering qui trattati sono caratterizzati dalla evoluzione di un campo scalare classico con il ruolo di DE, e dalla interazione che le particelle di Materia Oscura (DM) hanno con questo campo. Considerando le particelle DM in moto attraverso il fluido DE, esse osservano un flusso di momento diverso da zero, indice di una forza proporzionale alla sezione d'urto di scattering tra DE e DM.
Nel presente lavoro sono stati analizzati dati provenienti da simulazioni cosmologiche N-body DM-only per cinque modelli: due a equazione di stato DE costante, due con equazione di stato dipendente dal tempo, e infine il modello standard LCDM come base di confronto. Le condizioni iniziali sono uguali per tutti i modelli, in modo tale che ogni differenza rilevata nei risultati sia riconducibile agli effetti dei diversi modelli cosmologici.
Sono stati ricavati i profili di densità e, per la prima volta su questi dati, i profili di velocità, di un significativo di aloni di materia oscura per ogni cosmologia, divisi in bin di massa e per tre redshift.
Viene evidenziato come il termine aggiuntivo di drag nei modelli dark scattering abbia due effetti diversi nella crescita delle strutture. Nel regime lineare, infatti, le particelle DM in infall verso il centro degli ammassi hanno una direzione radiale del moto e l'attrito con il fluido DE le fa rallentare, diminuendo la loro velocità. Quando passano al regime non lineare, acquistano una componente tangenziale di velocità che di fatto fa sì che l'interazione con l'energia oscura provochi una perdita di energia cinetica con conseguente collasso più rapido.
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Newcomb, Cecile Gaines. « Imagine Blacksburg : Using immersive 3D models to explore density ». Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79485.
Texte intégralRésumé :
This project explores the challenges of increasing density in a college town grappling with how to appropriately respond to expected population growth. It presents a concept idea for a section of Downtown Blacksburg, Virginia that meets the various planning goals for the community. It also experiments with an innovative way of presenting and fostering discussion around this kind of vision by inviting stakeholders to experience models of the concept in an immersive three dimensional environment.
Common negative perceptions of density lead to resistance to increased density projects by the public and elected representatives. While there seems to be a consensus of understanding that denser development is preferable to sprawl, Americans in communities across the country have been resisting efforts to increase density. In Blacksburg higher density is often met with fear of student housing located too close to single family neighborhoods. Density resistance is rooted largely in the lack of general knowledge of what density looks like, how it is built, and how it feels once built. The negative aspects of high density neighborhoods, which have caused fearful reactions, are results of poor design, not an inevitability caused by density. This thesis uses two approaches to argue for the advantages of higher density development. Methods include background research of densification elsewhere, a neighborhood redevelopment proposal, and a research event in which a select group of participants completed surveys, viewed presentations of 3D computer models of virtual developments in Blacksburg, and discussed their opinions and thoughts about the models and proposal. This project has demonstrated that 3D modeling is a more effective planning tool for helping decision-makers perceive density and understand the value of quality designs than typical planning tools based on 2D presentations.Master of Urban and Regional Planning
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Karlsson, Christian. « Regression Models of 3D Wakes for Propellers ». Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-67785.
Texte intégralRésumé :
In this work, regression models for the wake field entering a propeller at certain axial andnominal position have been proposed. Wakes are non-uniform flows following a body immersedin a viscous fluid. We have proposed models for the axial and tangential velocity distribution asfunctions of ship hull and propeller measures. The regression models were modelled using Fourierseries and parameter estimations based on skewed-Gaussian and sine functions. The wake fieldis an important parameter in propeller design. The regression models are based on experimentaldata provided by the Rolls-Royce Hydrodynamic Research Center in Kristinehamn. Also we havestudied the flow in the axial velocity distribution in the propeller plane using the coherent structurecoloring method. The coherent structure coloring is used to study coherent patterns by looking atfluid particle kinematics. Using this type of analysis, we observed that the velocity distributionbehaves kinematically similar in the different regions of the wake distribution, which according tothe coherent structure coloring indicate coherence.I det här arbetet, har regressionsmodeller för medströmsfältet in i en propeller vid viss axielloch nominell position utvecklats. Medströmsfältet är ojämn strömning efter en kropp nedsänkt i enviskös vätska. Vi har föreslagit modeller för axiell och tangentiell hastighetsfördelning som funktionerför fartygsskrov-och propeller-parametrar. Regressionsmodellerna modellerades med hjälpav Fourier-serier och parameterskattning baserade på skeva Gaussfördelningar och sinusfunktioner.Medströmsfältet är en viktig parameter i propeller design. Regressionsmodellerna är baserade påexperimentella data från Rolls-Royces Hydrodynamiska Forskningscenter i Kristinehamn. Vi harockså studerat flödet i axialhastighetsfördelningen i propellplanet med hjälp av den koherenta struktureringsfärgmetoden.Den koherenta struktureringsfärgmetoden används för att studera koherentamönster genom att titta på vätskepartikelkinematik. Med hjälp av denna typ av analys observeradevi att hastighetsfördelningen uppför sig kinematiskt lika i de olika regionerna i medströmsfältet,vilket enligt koherenta strukturfärgmetoden indikerar koherens.
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Silvennoinen, H. (Hanna). « 3D structure of the crust and upper mantle beneath Northern Fennoscandian shield ». Doctoral thesis, University of Oulu, 2015. http://urn.fi/urn:isbn:9789526210681.
Texte intégralRésumé :
Abstract
The crustal and upper mantle structures of the Shield on the regional scale were
investigated using the data of the POLENET/LAPNET passive seismic array and
the previously published models of active and passive seismic experiments in the
study area. This area is centred in northern Finland and it extends to surrounding
areas in Sweden, Norway and northwestern Russia. The bedrock there is mostly of
the Archaean origin and the lithosphere of the region was reworked by two orogenies
during Palaeoproterozoic.
One of the results of the thesis was a new map of the Moho depth of the study area,
for which new estimates of the crustal thickness were obtained using receiver function
method and complemented by published results of receiver function studies and controlled
source seismic profiles. The map differs from the previously published maps in
two locations, where we found significant deepening of the Moho. The 3D structure of
the upper mantle was studied using teleseismic traveltime tomography method. The
resulting model shows high seismic velocities below three cratonic units of the study
area, which may correspond to non-reworked fragments of cratonic lithosphere and a
low velocity anomaly separating these cratonic units from each other.
The regional scale studies were complemented by two smaller scale studies in upper
crust level using combined interpretation of seismic profiling and gravity data. These
studies were centred on Archaean Kuhmo Greenstone Belt in eastern Finland and
central Lapland in northern Finland located in the crust reworked during Palaeoproterozoic.
Both areas are considered as prospective ones for mineral exploration. Both
studies demonstrate the advantage of gravity data inversion in studying 3D density
structure of geologically interesting formations, when the Bouguer anomaly data is
combined with a priori information from petrophysical and seismic datasets.
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Decker, Jeramy Bruyn. « Building, Updating and Verifying Fracture Models in Real Time for Hard Rock Tunneling ». Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27220.
Texte intégralRésumé :
Fractures and fracture networks govern the mechanical and fluid flow behavior of rock masses. Tunneling and other rock mechanics applications therefore require the characterization of rock fractures based on geological data. Field investigations produce only a limited amount of data from boreholes, outcrops, cut slopes, and geophysical surveys. In tunneling, the process of excavation creates a priceless opportunity to gather more data during construction. Typically, however, these data are not utilized due to the impedance of sampling and analysis on the flow of construction, and safety concerns with sampling within unlined tunnel sections. However, the use of this additional data would increase the overall safety, quality, and cost savings of tunneling.
This study deals with several aspects of the above, with the goal of creating methods and tools to allow engineers and geologists to gather and analysis fracture data in tunnels without interrupting the excavation and without compromising safety. Distribution-independent trace density and mean trace length estimators are developed using principles of stereology. An optimization technique is developed utilizing Differential Evolution to infer fracture size and shape from trace data obtained on two or more nonparallel sampling planes. A method of producing nearly bias free empirical trace length CDF's is also introduced. These new methods and tools were validated using Monte Carlo simulations. A field study was conducted in an existing tunnel allowing the above methods and tools to be further validated and tested. A relational database was developed to aid in storage, retrieval, and analysis of field data. Fracture models were built and updated using fracture data from within the tunnel. Utilization of state of the art imaging techniques allowed for remote sampling and analysis, which were enhanced by the use of 3d visualization techniques.Ph. D.
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Baumgarten, Lars. « Gesteinsmechanische Versuche und petrophysikalische Untersuchungen – Laborergebnisse und numerische Simulationen ». Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-202612.
Texte intégralRésumé :
Dreiaxiale Druckprüfungen können als Einstufenversuche, als Mehrstufenversuche oder als Versuche mit kontinuierlichen Bruchzuständen ausgeführt werden. Bei der Anwendung der Mehrstufentechnik ergeben sich insbesondere Fragestellungen hinsichtlich der richtigen Wahl des Umschaltpunktes und des optimalen Verlaufs des Spannungspfades zwischen den einzelnen Versuchsstufen. Fraglich beim Versuch mit kontinuierlichen Bruchzuständen bleibt, ob im Versuchsverlauf tatsächlich Spannungszustände erfasst werden, welche die Höchstfestigkeit des untersuchten Materials repräsentieren. Die Dissertation greift diese Fragestellungen auf, ermöglicht den Einstieg in die beschriebene Thematik und schafft die Voraussetzungen, die zur Lösung der aufgeführten Problemstellungen notwendig sind. Auf der Grundlage einer umfangreichen Datenbasis gesteinsmechanischer und petrophysikalischer Kennwerte wurde ein numerisches Modell entwickelt, welches das Spannungs-Verformungs-, Festigkeits- und Bruchverhalten eines Sandsteins im direkten Zug- und im einaxialen Druckversuch sowie in dreiaxialen Druckprüfungen zufriedenstellend wiedergibt. Das Festigkeitsverhalten des entwickelten Modells wurde in Mehrstufentests mit unterschiedlichen Spannungspfaden analysiert und mit den entsprechenden Laborbefunden verglichen.
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Fenollosa, Artés Felip. « Contribució a l'estudi de la impressió 3D per a la fabricació de models per facilitar l'assaig d'operacions quirúrgiques de tumors ». Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667421.
Texte intégralRésumé :
La present tesi doctoral s’ha centrat en el repte d’aconseguir, mitjançant Fabricació Additiva (FA), models per a assaig quirúrgic, sota la premissa que els equips per fer-los haurien de ser accessibles a l’àmbit hospitalari. L’objectiu és facilitar l’extensió de l’ús dels prototips com a eina de preparació d’operacions quirúrgiques, transformant la pràctica mèdica actual de la mateixa manera que en el seu moment ho van fer tecnologies com les que van facilitar l’ús de radiografies. El motiu d’utilitzar FA, en lloc de tecnologies més tradicionals, és la seva capacitat de materialitzar de forma directa les dades digitals obtingudes de l’anatomia del pacient mitjançant sistemes d’escanejat tridimensional, fent possible l’obtenció de models personalitzats. Els resultats es centren en la generació de nou coneixement sobre com aconseguir equipaments d’impressió 3D multimaterials accessibles que permetin l’obtenció de models mimètics respecte als teixits vius. Per facilitar aquesta buscada extensió de la tecnologia, s’ha focalitzat en les tecnologies de codi obert com la Fabricació per Filament Fos (FFF) i similars basades en líquids catalitzables. La recerca s’alinea dins l’activitat de desenvolupament de la FA al CIM UPC, i en aquest àmbit concret amb la col·laboració amb l’Hospital Sant Joan de Déu de Barcelona (HSJD). El primer bloc de la tesi inclou la descripció de l’estat de l’art, detallant les tecnologies existents i la seva aplicació a l’entorn mèdic. S’han establert per primer cop unes bases de caracterització dels teixits vius -sobretot tous- per donar suport a la selecció de materials que els puguin mimetitzar en un procés de FA, a efectes de millorar l’experiència d’assaig dels cirurgians. El caràcter rígid dels materials majoritàriament usats en impressió 3D els fa poc útils per simular tumors i altres referències anatòmiques. De forma successiva, es tracten paràmetres com la densitat, la viscoelasticitat, la caracterització dels materials tous a la indústria, l’estudi del mòdul elàstic de teixits tous i vasos, la duresa d’aquests, i requeriments com l’esterilització dels models. El segon bloc comença explorant la impressió 3D mitjançant FFF. Es classifiquen les variants del procés des del punt de vista de la multimaterialitat, essencial per fer models d’assaig quirúrgic, diferenciant entre solucions multibroquet i de barreja al capçal. S’ha inclòs l’estudi de materials (filaments i líquids) que serien més útils per mimetitzar teixits tous. Es constata com en els líquids, en comparació amb els filaments, la complexitat del treball en processos de FA és més elevada, i es determinen formes d’imprimir materials molt tous. Per acabar, s’exposen sis casos reals de col·laboració amb l’HJSD, una selecció d’aquells en els que el doctorand ha intervingut en els darrers anys. L’origen es troba en la dificultat de l’abordatge d’operacions de resecció de tumors infantils com el neuroblastoma, i a la iniciativa del Dr. Lucas Krauel. Finalment, el Bloc 3 té per objecte explorar nombrosos conceptes (fins a 8), activitat completada al llarg dels darrers cinc anys amb el suport dels mitjans del CIM UPC i de l’activitat associada a treballs finals d’estudis d’estudiants de la UPC, arribant-se a materialitzar equipaments experimentals per validar-los. La recerca ampla i sistemàtica al respecte fa que s’estigui més a prop de disposar d’una solució d’impressió 3D multimaterial de sobretaula. Es determina que la millor via de progrés és la de disposar d’una pluralitat de capçals independents a fi de capacitar la impressora 3D per integrar diversos conceptes estudiats, materialitzant-se una possible solució. Cloent la tesi, es planteja com seria un equipament d’impressió 3D per a models d’assaig quirúrgic, a fi de servir de base per a futurs desenvolupaments.La presente tesis doctoral se ha centrado en el reto de conseguir, mediante Fabricación Aditiva (FA), modelos para ensayo quirúrgico, bajo la premisa que los equipos para obtenerlos tendrían que ser accesibles al ámbito hospitalario. El objetivo es facilitar la extensión del uso de modelos como herramienta de preparación de operaciones quirúrgicas, transformando la práctica médica actual de la misma manera que, en su momento, lo hicieron tecnologías como las que facilitaron el uso de radiografías. El motivo de utilizar FA, en lugar de tecnologías más tradicionales, es su capacidad de materializar de forma directa los datos digitales obtenidos de la anatomía del paciente mediante sistemas de escaneado tridimensional, haciendo posible la obtención de modelos personalizados. Los resultados se centran en la generación de nuevo conocimiento para conseguir equipamientos de impresión 3D multimateriales accesibles que permitan la obtención de modelos miméticos respecto a los tejidos vivos. Para facilitar la buscada extensión de la tecnología, se ha focalizado en las tecnologías de código abierto como la Fabricación por Hilo Fundido (FFF) y similares basadas en líquidos catalizables. Esta investigación se alinea dentro de la actividad de desarrollo de la FA en el CIM UPC, y en este ámbito concreto con la colaboración con el Hospital Sant Joan de Déu de Barcelona (HSJD). El primer bloque de la tesis incluye la descripción del estado del arte, detallando las tecnologías existentes y su aplicación al entorno médico. Se han establecido por primera vez unas bases de caracterización de los tejidos vivos – principalmente blandos – para dar apoyo a la selección de materiales que los puedan mimetizar en un proceso de FA, a efectos de mejorar la experiencia de ensayo de los cirujanos. El carácter rígido de los materiales mayoritariamente usados en impresión 3D los hace poco útiles para simular tumores y otras referencias anatómicas. De forma sucesiva, se tratan parámetros como la densidad, la viscoelasticidad, la caracterización de materiales blandos en la industria, el estudio del módulo elástico de tejidos blandos y vasos, la dureza de los mismos, y requerimientos como la esterilización de los modelos. El segundo bloque empieza explorando la impresión 3D mediante FFF. Se clasifican las variantes del proceso desde el punto de vista de la multimaterialidad, esencial para hacer modelos de ensayo quirúrgico, diferenciando entre soluciones multiboquilla y de mezcla en el cabezal. Se ha incluido el estudio de materiales (filamentos y líquidos) que serían más útiles para mimetizar tejidos blandos. Se constata como en los líquidos, en comparación con los filamentos, la complejidad del trabajo en procesos de FA es más elevada, y se determinan formas de imprimir materiales muy blandos. Para acabar, se exponen seis casos reales de colaboración con el HJSD, una selección de aquellos en los que el doctorando ha intervenido en los últimos años. El origen se encuentra en la dificultad del abordaje de operaciones de resección de tumores infantiles como el neuroblastoma, y en la iniciativa del Dr. Lucas Krauel. Finalmente, el Bloque 3 desarrolla numerosos conceptos (hasta 8), actividad completada a lo largo de los últimos cinco años con el apoyo de los medios del CIM UPC y de la actividad asociada a trabajos finales de estudios de estudiantes de la UPC, llegándose a materializar equipamientos experimentales para validarlos. La investigación amplia y sistemática al respecto hace que se esté más cerca de disponer de una solución de impresión 3D multimaterial de sobremesa. Se determina que la mejor vía de progreso es la de disponer de una pluralidad de cabezales independientes, a fin de capacitar la impresora 3D para integrar diversos conceptos estudiados, materializándose una posible solución. Para cerrar la tesis, se plantea cómo sería un equipamiento de impresión 3D para modelos de ensayo quirúrgico, a fin de servir de base para futuros desarrollos.
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Iorga-Simăn, Victor. « Etude par simulation numérique des écoulements dans le conduit d’admission d’un moteur à levée de soupape d’admission variable ». Thesis, Paris, CNAM, 2012. http://www.theses.fr/2012CNAM0800/document.
Texte intégralRésumé :
L’impact négatif de l’automobile sur l’environnement a entraîné une sévérisation des normes législatives pour protéger celui-ci. Les difficultés rencontrées lors de l’amélioration du rendement du moteur à allumage commandé, résultent principalement de son fonctionnement inefficace à charges partielles. La distribution variable est capable d'améliorations concernant la réduction de la consommation de carburant, surtout dans une zone d’utilisation fréquente : basses charges et bas régimes. Une alternative à l’étude expérimentale est l’approche par simulation numérique, CFD en utilisant le logiciel ANSYS-Fluent. Dans cette thèse de doctorat, le but principal a été de déterminer les vitesses d’écoulement du fluide pendant le processus d’admission pour deux lois de levée de la soupape, pour un moteur entraîné à 815 tr/min et une ouverture du papillon de gaz de 21.6°. Dans ce but, on a utilisé deux modèles de simulation numérique: un modèle bidimensionnel et un modèle tridimensionnel. L’étude réalisée par simulation numérique a permis de clarifier quelques aspects importants concernant les vitesses d’écoulement de l’air dans le cylindre et le degré de turbulenceThe negative impact of automobiles on the environment has led to increased severity in the legislation concerning environmental protection. The problems encountered in the efforts intended to improve the efficiency of the spark ignition engine are derived from its inefficient operation under partial loads. The variable intake valve lift is capable of significant changes aiming at lower fuel consumption, especially in the frequent use area: low torque, low speed. An alternative to the experimental study of fluid flow is the approach by numerical simulation, CFD, using the software ANSYS-Fluent. The main purpose of the present doctoral thesis was to determine the fluid flow velocity during the intake, for two intake valve lift laws, when the engine is running at 815 rpm, and with an opening of the throttle plate at 21.6°. To do this, we have used two numerical simulation models: one two-dimensional, and one three-dimensional. The study by numerical simulation made it possible to clarify some important issues regarding the air flow velocity into the cylinder, and the level of turbulence
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Chen, Bo. « Efficient Smoothing and Interpolation of Velocity Models for Seismic Wavefront Construction Algorithms ». Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-9761.
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The wavefront construction (WFC) method is an effective tool to compute seismic ray fields and has wide applications. This paper applies the WFC method to a heterogeneous earth model represented as a 3-D grid instead of a sequence of smooth layers, as the layered model is insufficient for the regions with complex geological structures. In order to utilize gridded models, highly heterogeneous models must be smoothed for reliable numerical results. A new velocity gradient smoothing method is proposed that is able to control quantitatively the smoothness of the velocity model while preserving the main structural characteristics of the original model. A modified inverse distance weighting method is applied to obtain velocities or densities at an arbitrary point in the model for successive wavefront propagation. A very complex 3-D grid model based on the standard Marmousi reference model is tested to compare the new approach to alternative smoothing schemes, and the first arrival travel times from the WFC method are compared with results from an eikonal solver. These results are obtained more quickly, but the algorithm is restricted to computing only first arrivals. However, comparison helps to establish the accuracy of the WFC solutions and assess the influence of the smoothing schemes. The modeling comparisons verify the effectiveness of the proposed smoothing methods and the enhanced performance of the WFC algorithm with the 3-D grid model.
Livres sur le sujet "Velocity and Density 3D models"
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John F. Kennedy Space Center. et United States. National Aeronautics and Space Administration. Scientific and Technical Information Program., dir. Statistical short-range guidance for peak wind speed forecasts on Kennedy Space Center/Cape Canaveral Air Force Station : Phase 1 results. [Washington, D.C.] : National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 2002.
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John F. Kennedy Space Center. et United States. National Aeronautics and Space Administration. Scientific and Technical Information Program., dir. Statistical short-range guidance for peak wind speed forecasts on Kennedy Space Center/Cape Canaveral Air Force Station : Phase 1 results. [Washington, D.C.] : National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 2002.
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Pierson, Willard J. Probabilities and statistics for backscatter estimates obtained by a scatterometer with applications to new scatterometer design data. [Washington, DC] : National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1989.
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Statistical short-range guidance for peak wind speed forecasts on Kennedy Space Center/Cape Canaveral Air Force Station : Phase 1 results. [Washington, D.C.] : National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 2002.
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Deruelle, Nathalie, et Jean-Philippe Uzan. Self-gravitating fluids. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198786399.003.0015.
Texte intégralRésumé :
This chapter briefly describes ‘perfect fluids’. These are characterized by their mass density ρ(t, xⁱ), pressure p(t, ⁱ), and velocity field v(t, ⁱ). The motion and equilibrium configurations of these fluids are determined by the equation of state, for example, p = p(ρ) for a barotropic fluid, and by the gravitational potential U(t, ⁱ) created at a point ⁱ by other fluid elements. The chapter shows that, given an equation of state, the equations of the problem to be solved are the continuity equation, the Euler equation, and the Poisson equation. It then considers static models with spherical symmetry, as well as polytropes and the Lane–Emden equation. Finally, the chapter studies the isothermal sphere and Maclaurin spheroids.
Chapitres de livres sur le sujet "Velocity and Density 3D models"
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Petković, Uroš, Robert Korez, Stefan Parent, Samuel Kadoury et Tomaž Vrtovec. « 3D Cobb Angle Measurements from Scoliotic Mesh Models with Varying Face-Vertex Density ». Dans Computational Methods and Clinical Applications in Musculoskeletal Imaging, 48–58. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-74113-0_5.
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Kawabata, Takeshi. « Rigid-Body Fitting of Atomic Models on 3D Density Maps of Electron Microscopy ». Dans Advances in Experimental Medicine and Biology, 219–35. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2200-6_14.
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Garrett, Steven L. « Ideal Gas Laws ». Dans Understanding Acoustics, 333–56. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44787-8_7.
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Abstract This is the first chapter to explicitly address fluid media. For springs and solids, Hooke’s law, or its generalization using stress, strain, and elastic moduli provided an equation of state. In fluids, we have an equation of state that relates changes in pressure (stresses) to changes in density (strain). The simplest fluidic equations of state are the Ideal Gas Laws. Our presentation of these laws will combine microscopic models that treat gas atoms as hard spheres with phenomenological (thermodynamic) models that combine the variables that describe the gas with conservation laws that restrict those variables. The combination of microscopic and phenomenological models will give us the important characteristics of gas behavior under isothermal or adiabatic conditions and will provide relationships between gas heat capacities and their constituent particles when augmented with elementary concepts from quantum mechanics. The chapter ends by adding a velocity field to the pressure, temperature, and density, thus providing the equations of hydrodynamics that will guide all of the subsequent development of acoustics in fluids.
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Tran, Thu-Hang. « Preliminary Regression Study on Air Quality Inside a Road Tunnel : A Case Study in Vietnam ». Dans Lecture Notes in Civil Engineering, 95–102. Singapore : Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1260-3_9.
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AbstractNormal air quality that ensures the visibility and brings no harmful impact to the health of the vehicle drivers is essential for all road tunnels. It is affected by various issues. In this paper, the air quality – meteorology – traffic volume correlations were quested in the case study of an opened road tunnel on Vietnam National Highway 1A. The linear regression modelling technics using the least squares method with 95% of confidence was executed. Four representative models of the total suspended particles and airborne lead concentration against the meteorological parameters (temperature, relative humidity, wind velocity) and the vehicle flow density inside tunnel were proposed. The correlations with the volatile organic compounds were also studied but no representative model was proposed. Further studies on a richer source of data were suggested. The study confirmed the role of the in-tunnel vehicle volume and the meteorology on the tunnel’s air quality.
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Conesa-Boj, Sonia, Sonia Estrade, Josep M., Joan D., A. Cirera, Joan R., Francesca Peiro et Jordi Arbiol. « Advanced Electron Microscopy Techniques on Semiconductor Nanowires : from Atomic Density of States Analysis to 3D Reconstruction Models ». Dans Nanowires. InTech, 2010. http://dx.doi.org/10.5772/39511.
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Zhang, Wenbo, Stephen T. Johnston et Claire A. Currie. « Numerical models of Cretaceous continental collision and slab breakoff dynamics in western Canada ». Dans Plate Tectonics, Ophiolites, and Societal Significance of Geology : A Celebration of the Career of Eldridge Moores. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2552(06).
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ABSTRACT The North American Cordillera is generally interpreted as a result of the long-lived, east-dipping subduction at the western margin of the North American plate. However, the east-dipping subduction seems problematic for explaining some of the geological features in the Cordillera such as large volume back-arc magmatism. Recent studies suggested that westward subduction of a now-consumed oceanic plate during the Cretaceous could explain these debated geological features. The evidence includes petrological and geochemical variations in magmatism, the presence of ophiolite that indicates tectonic sutures between the Cordillera and Craton, and seismic tomography images showing high-velocity bodies within the underlying convecting mantle that are interpreted as slab remnants from the westward subduction. Here we use 2-D upper mantle-scale numerical models to investigate the dynamics associated with westward subduction and Cordillera-Craton collision. The models demonstrate the controls on slab breakoff (remnant) following collision including: (1) oceanic and continental mantle lithosphere strength, (2) variations in density (eclogitization of continental lower crust and cratonic mantle lithosphere density), and (3) convergence rate. Our preferred model has a relatively weak mantle lithosphere, eclogitization of the lower continental crust, cratonic mantle lithosphere density of 3250 kg/m3, and a convergence rate of 5 cm/yr. It shows that collision and slab breakoff result in an ∼2 km increase in surface elevation of the Cordilleran region west of the suture as the dense oceanic plate detaches. The surface also shows a foreland geometry that extends >1000 km east of the suture with ∼4 km of subsidence relative to the adjacent Cordillera.
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Bhowmick, Brojeshwar. « 3D Reconstruction Using Multiple View Stereo and a Brief Introduction to Kinect ». Dans Research Developments in Computer Vision and Image Processing, 15–37. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-4558-5.ch002.
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This chapter deals with the methodology of 3D reconstruction, both sparse and dense. The basic properties of the projective geometry and the camera models are introduced to understand the preliminaries about the subject. A more detail can be found in the book (Hartley & Zisserman, 2000). The sparse reconstruction deals with reconstructing 3D points for few image points. There are gaps in the reconstructed 3D points. Dense reconstruction tries to fill up gaps and make the density of the reconstruction higher. Estimation of correspondences is an integral part of multiview reconstruction and the author will discuss the point correspondences among images here. Finally the author will introduce the Microsoft Kinect, a divice which directly capture 3D information in realtime, and will show how to enhance the Kinect point cloud using vision framework.
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Bers, Abraham. « Collisions and collisional transport—II. Fully-ionized plasmas—Unmagnetized ». Dans Plasma Physics and Fusion Plasma Electrodynamics, 365–98. Oxford University PressOxford, 2016. http://dx.doi.org/10.1093/acprof:oso/9780199295784.003.0006.
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Abstract This chapter expands the discussion of collisional scattering of particles by examining collisional relaxation rates and some collisional transport characteristics in unmagnetized, fully-ionized plasmas. The material is presented here so that students can develop qualitative and quantitative knowledge about the effects of collisions and some important collisional transport phenomena in such plasmas. This is particularly relevant at this stage, since collective modes of waves and instabilities in high-temperature plasmas are conveniently studied, in first-approximation, from “collisionless” models of plasma dynamics. To gain some insight into the dynamics of elastic Coulomb collisional processes—the binary elastic collision between two charged particles interacting through their own electric field—the chapter considers the evolution of a tenuous beam of “test” particles at a given velocity, colliding with a Maxwellian distribution of “field” particles, of density and temperature, which is much more numerous and remains (at least initially) essentially unchanged.
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Panchenko, Vladimir, et Valeriy Kharchenko. « Development and Research of PVT Modules in Computer-Aided Design and Finite Element Analysis Systems ». Dans Advances in Environmental Engineering and Green Technologies, 314–42. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-5225-9420-8.ch013.
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This chapter discusses the simulation of solar photovoltaic thermal modules of planar and concentrator structures in computer-aided design systems KOMPAS 3D and finite element analysis ANSYS. To create photovoltaic thermal modules, a method for designing their three-dimensional models in the computer-aided design system has been developed. To study the thermal regimes of the created three-dimensional models of modules, a method has been developed for visualizing thermal processes, coolant velocity, and flow lines of a cooling agent in a finite element analysis system. As a result of calculations in the finite element analysis system using the developed method, conclusions can be drawn about the feasibility of the design created with its further editing, visualization of thermal fields, and current lines of the radiator cooling agent. As an illustration of the simulation results, a three-dimensional model of a photovoltaic thermal planar roofing panel and an optimized three-dimensional model of a photodetector of a solar concentrator photovoltaic thermal module are presented.
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Marino, Eva, Stefano Arellano-Pérez, Santiago Martín-Alcón et José Luis Tomé. « Canopy fuel modelling in Mediterranean forest stands with airborne LiDAR data at regional scale : preliminary results ». Dans Advances in Forest Fire Research 2022, 1416–22. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_215.
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Canopy fuel characterization is highly relevant for wildfire prevention, especially in the context of extreme events involving crown fires. Airborne laser scanning has been proven very useful to retrieve 3D forest structure at large scales, becoming freely available in many countries in the recent years which provide an opportunity to map fuel parameters that are critical for fire behaviour simulation. Previous studies on canopy fuel modelling predict canopy base height (CBH), fuel load (CFL) and bulk density (CBD) mainly in tree species from temperate conifer forest, with specific models still lacking for the main Mediterranean forest stands and especially deciduous species. This work presents preliminary results of models obtained from low density airborne LiDAR data (1.5 p/m2) for canopy fuel characterization of critical structural variables (CBH, CFL and CBD) in the main Mediterranean forest stands existing in Andalusia region, including Pinus sp, Quercus sp and Eucalyptus sp tree species. A set of 750 plots are used to characterize canopy fuels in 15 different forest stands representative of Mediterranean tree species, with a samplig design that consider structural heterogeneity in a wide study area (29000 km2). Different modelling techniques are tested to selected the best formulation and input LiDAR metrics to be included in the final models for each fuel parameter, that are used to generate high resolution maps of canopy fuels at regional scale.
Actes de conférences sur le sujet "Velocity and Density 3D models"
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Makris, J., C. H. Henke, D. Harrison et R. Boyce. « 3D Modelling of Velocity and Density Models for the Interpretation of Regional and Local Geological Structures ». Dans 57th EAEG Meeting. Netherlands : EAGE Publications BV, 1995. http://dx.doi.org/10.3997/2214-4609.201409264.
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Wang, Shilong, Yuanyuan Ding, Changfeng Wang, Zhijun Zheng et Jilin Yu. « Effect of Relative Density on the Dynamic Impact Behaviors of Closed-Cell Foam ». Dans ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54562.
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Dynamic behaviors of closed-cell foam are investigated with cell-based finite element models based on the 3D Voronoi technique. The typical deformation feature of cellular structures under high-velocity impact is layer by layer collapse, like a shock wave propagating in the specimen. The one-dimensional velocity distribution of the structure is calculated to characterize the propagation of shock front and thus the shock wave speed is determined quantitatively. It is found that the shock wave speed has intense dependence on the impact velocity for a specific relative density. The difference between the shock wave speed and the impact velocity is asymptotic to a constant as the impact velocity increases. This constant can be therefore regarded as a dynamic material parameter. The influence of relative density on this dynamic material parameter is investigated. The results show that the shock wave speed at a specific impact velocity increases with the increase of the relative density of cellular structure in a certain extent. An expression of the shock wave speed with respect to the impact velocity and relative density is obtained. The dynamic strain hardening parameter is lower than that in the quasi-static one, which indicates different mechanisms of the deformation under high-velocity and quasi-static loadings.
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Tardy, Philippe M. J. « A Fast 3D Model for Annular Flows of Wellbore Completion Fluids ». Dans ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95133.
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Abstract This paper presents a novel approach to solving the 3D flow and displacement of completion fluids in the annulus formed by the gap between the outer wall of the casing and the wellbore rock face. Completion fluids displace each-other and follow a complex path promoted by rheology and density contrasts, casing movement and by the shape and orientation of the annulus. Muds and cement slurries often exhibit a yield stress, an additional challenge for optimal mud removal and cement coverage. This work extends previously published 2D models, to now capture fluid distribution and velocity profiles across the gap width in the 3D axial-azimuthal-radial space, at a lower computer cost than with conventional 3D CFD approaches. This gain is obtained by solving a 2D-only pressure equation for calculating the 3D annular flow, under the so-called narrow-gap approximation.
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Gómez, Pablo, Claudio Zanzi, Julián Palacios, Julio Hernández et Joaquín López. « An Adaptive-Grid Projection Method for High Density Ratio Interfacial Flows ». Dans ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64652.
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A graded-adaptive grid projection method to solve the Navier-Stokes equations for incompressible interfacial flows characterized by large density ratios is presented. The numerical model is similar to the one we proposed in [7] and extended to 3D problems in [8]. The free surface is described using a level set method. A Godunov-type method and a Crank-Nicholson temporal discretization scheme are used to solve the advection equation of the level set function and to update of the momentum equation. The reinitialization procedure of the distance function is based on solving a hyperbolic equation to steady state using third-order Runge-Kutta and fifth-order WENO schemes. The conservation equations are discretized on a rectangular adaptive grid with an octree data structure and the pressure stored at the grid cell vertices. In order to avoid spurious pressure oscillations, the velocity components are stored at the cell edges. This new storage scheme combines the advantages of vertex-based schemes, in which the nodes where the pressure is stored are aligned, and cell center-based schemes, which avoid pressure-velocity coupling problems. The numerical model incorporates a continuous surface tension model based on the balanced-force algorithm proposed in [6]. A special treatment of T-nodes (nodes located at vertices, edges or faces of cells belonging to two different refinement levels) is proposed that considerably improves the efficiency of the method. Several tests in two and three dimensions have been carried out to assess the accuracy and efficiency of the proposed method. In this work we present some numerical results for a 3D kinematic test, which are compared with those obtained by other authors. We also present results for the impact of a drop of water onto a liquid surface, which are compared with experimental visualization results.
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Hormozi, S., B. Firoozabadi, H. Ghasvari-Jahromi et S. M. H. Moosavi Hekmati. « 3-D Modeling of Particle Laden Density Current ». Dans ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14640.
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The gravity currents on the inclined boundaries are formed when the inflow fluid has a density difference with the ambient fluid and a tangential component of gravity becomes the driving force. If the density difference arises from the suspension of particles, the currents are known as particle-driven density currents, in which the local density of the gravity current depends on the concentration of particles. A low Reynolds k-ε turbulence model is used to simulate three dimensional turbidity currents. Also a laboratory apparatus was built to study the 3D flow resulting from the release of particle laden density currents on a sloping surface in a channel of freshwater via a sluice gate and Kaolin was used as the suspended material. The height, width, velocity and concentration profiles are calculated and compared with the laboratory experiments which show good agreement. Averaged parameters were obtained and Entrainment coefficients against Richardson number were acquired without any approximation and simplification which show the same trend as previous 2D experimental data.
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Imine, Bachir, Miloud Abidat, Omar Imine, Hichem Gazzah et Iskender Go¨kalp. « Study of Turbulent Variable Density Jets With Different Asymmetric Geometries ». Dans ASME 7th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2004. http://dx.doi.org/10.1115/esda2004-58571.
Texte intégralRésumé :
In the present study, the effects of inlet jet geometry on the process of mixture with variable density have been investigated numerically. Three density ratios were considered, namely 1.0, 1.8 and 0.66 for Air-air, CH4-Air and CO2-Air mixtures respectively. The jets are produced through rectangular, elliptic and triangular tubes with aspect ratio 1.33. A second-order Reynolds stress model (RSM) is used to investigate variable density effects in asymmetric turbulent jets. Comparative studies are presented in the case of the calculations of the average variables such as the longitudinal velocity, species and the turbulent kinetic energy. The results obtained show that the asymmetric geometry noticeably enhances mixture in comparison with the axisymmetric case. Typical phenomenon of 3D jets are observed.
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Mahgoub, Mohamed, Guillaume Cambois, James Cowell et Suaad Khoori. « Benefits of Ultra-Dense 3D Spatial Sampling for Seismic Processing and Interpretation ». Dans Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207719-ms.
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Abstract The advances in seismic acquisition systems, especially onshore nodes, have made it possible to acquire ultra-dense 3D surveys at a reasonable cost. This new design enables accurate processing sequences that deliver higher resolution images of the subsurface. These images in turn lead to enhanced structural interpretation and better prediction of rock properties. In 2019, ADNOC and partners acquired an 81 square kilometer ultra-high density pilot survey onshore Abu Dhabi. The receivers were nimble nodes laid out on a 12.5x12.5m grid, which recorded continuously and stored the data on a memory chip. The sources were heavy vibrators sweeping the 2-110 Hz frequency range in 14 seconds on a 12.5x100m grid. 184 million traces per square kilometers did make such small area, the densest 3D seismic survey ever recorded. The single sensor data were expectedly very noisy and the unconstrained simultaneous shooting required elaborate deblending, but we managed these steps with existing tools. The dense 3D receiver grid actually enabled the use of interferometry-based ground-roll attenuation, a technique that is rarely used with conventional data due to inadequate sampling, but that resulted in increased signal-to-noise ratio. The data were migrated directly to depth using a velocity model derived after five iterations of tomographic inversion. The final image gathers were made of 18 reciprocal azimuths with 12.5m offset increment, resulting in 5,000 fold on a 6.25x6.25m grid. The main structural interpretation was achieved during the velocity model building stage. Key horizons were picked after the tomographic iterations and the velocity model was adjusted so that their depth matched the well markers. Anisotropic parameters were adjusted to maintain gather flatness and the new model was fed to the next iteration. This ultimately resulted in flat image gathers and horizons that tied to the wells. The final high-resolution data provided a much crisper image of the target clinoforms and faults. This resulted in a more detailed interpretation of the reservoirs. The data was subjected to pre-stack stratigraphic inversion. The availability of low frequency signal (down to 3 Hz) means that less well constraints are needed for the inversion. Preliminary results are particularly encouraging. Amplitude variations with azimuth have yet to be analyzed but data density bodes very well for the process. Ultra-dense 3D seismic acquisition is feasible and results in a step change in image quality. Structural and stratigraphic interpretation provided a more detailed image of faults and clinoforms. Stratigraphic inversion benefited from the low frequencies of the vibrator source and the increased spatial resolution.
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Hormozi, S., B. Firoozabadi et H. Ghasvari Jahromi. « 3-D Simulation of Sedimentation in Turbidity Currents ». Dans ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43584.
Texte intégralRésumé :
The gravity currents on the inclined boundaries are formed when the inflow fluid has a density difference with the ambient fluid and a tangential component of gravity becomes the driving force. If the density difference arises from the suspended particles, the currents are known as particle-laden density currents, or turbidity currents in which the local density depends on the concentration of particles. A low Reynolds k-ε turbulent model is used to simulate three dimensional turbidity currents. Also some laboratory tests were conducted to study the 3D flow resulting from the release of particle laden density currents on a sloping surface in a channel of freshwater via a sluice gate. Kaolin was used as the suspended material. The height, width, velocity and concentration profiles of turbidity currents were calculated and compared with the experimental data and showed good agreement. Different settling velocity formulas based on, first, solitary particle and, second, considering the effect of dispersed particles thorough the fluid are exerted in the concentration equation and the results compare with each other. Also the sedimentation heights of the turbidity current are simulated which are compatible with the experimental data.
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Jaimes Parilli, Diego, Armando Blanco et Janneth García. « Influence of PIG Mass, Launching Time and Turbulence Model on 3-D CFD Transient Simulation of PIG Motion ». Dans ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66956.
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Pigging procedures are common maintenance operations used to perform cleaning, draining and pipeline inspection in order to improve flow efficiency and operation cost. Despite these procedures are commonly used, questions still remain regarding the flow and the PIG motion features due to the complex interaction among pig, wall and flow, and the changes in internal fluid pressure and local fluid density. Currently, the PIG dynamic predictions are based on experimental data from short scale laboratory experiments and numerical models founded on physical simplification. So far, the transient of PIG motion calculated by methods that combine CFD and fluid-structure interaction in a 3D model and the influence of the physic and numerical features over the pig dynamics has not been analyzed yet. To provide a better understanding of pigging runs, this paper proposes a CFD methodology to obtain a 3D transient simulation of PIG motion. A moving control volume attached to the PIG let to solve the governing equation in a stationary mesh. This methodology is used to obtain the transient simulation of a PIG launched in a straight water pipeline for different PIG mass, launching time and turbulence models in order to study its influence over the PIG dynamics. The numerical results show a linear relation between the mass and the pressure drop in the transient state, but with no influence over the final stationary state. Also, an asymptotic relation between the transient pressure drop and the launching time was observed with no influence over the PIG terminal velocity. Besides, it is exposed the influence of the turbulence models (κ-ε, SST and BSL Reynolds Stress) in the results of pig motion; appreciable difference between the drop pressure of Omega-Based Stress Models (SST and BSL) and κ-ε turbulent model at steady state is shown, and, finally, a comparison of the velocity profiles at the interstice for each model was developed, this one shows an inaccuracy of the κ-ε model to describe the velocity profile in the walls proximities.
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Waqas, Muhammad, Lian Hou, Vincent Prieux, Adrien Meffre, Raffaela Sabetian, Hervé Prigent, Ahmed Saeed Alkaabi et al. « Velocity Model Building for Depth Imaging of Carbonate Reservoirs to the Deep Salt Incorporating Walkaway VSP and Gravity-Magnetic Data From OBC Survey Offshore Abu Dhabi ». Dans SPE Reservoir Characterisation and Simulation Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/212667-ms.
Texte intégralRésumé :
Abstract Use of depth imaging is increasing day by day in green as well as in brown fields. Velocity model is constructed by integration of multiple available datasets and techniques. Depth imaging based on a high-resolution velocity model constrained by wells resulted in improved image of the overburden as well as carbonate reservoirs to the deep salt using 3D OBC seismic, borehole seismic and Gravity-Magnetic data from two adjacent offshore fields in Abu Dhabi. Multi-Wave Inversion (MWI) utilizing direct arrivals, surface waves and two-way time surfaces was applied to obtain high-resolution velocity model in the near surface validated by checkshots and sonic logs. Near surface velocity inversions were detected by MWI which improved overall gather flatness in the near surface. The current stress regime as well as the network of faults resulted in HTI anisotropy in the dome area, which is visible on the multi-azimuthal Walkaway VSP travel-time residuals from the observed and modelled data. HTI is also visible on azimuthal move-out in Common Offset Common Azimuth (COCA) gathers. HTI tomography was tested, giving equally flat gathers achieved by azimuthal move-out correction. A Gravity-Magnetic survey covering the area was inverted and integrated for the deep salt and basement model. The basement was constrained by the results from magnetic depth estimation. Density model of deep salt sediments and basement was enhanced by Gravity-Magnetic inversion. The resulting density model was converted to velocity which was then incorporated in the final velocity model followed by tomographic update. Final imaging provided a better stacking response and improved gather flatness on the salt dome. High-resolution velocity model provided improved imaging, well ties and depth conversion. Improved AVO/AVA response helped patrial angles stacks for improved reservoir characterization. Improved imaging in the deep section was also achieved.
Rapports d'organisations sur le sujet "Velocity and Density 3D models"
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Reiter, Delaine T., et William L. Rodi. Validated 3D Velocity Models in Asia from Joint Regional Body- and Surface-Wave Tomography. Fort Belvoir, VA : Defense Technical Information Center, février 2009. http://dx.doi.org/10.21236/ada501242.
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Hordiienko, Valentyna V., Galyna V. Marchuk, Tetiana A. Vakaliuk et Andrey V. Pikilnyak. Development of a model of the solar system in AR and 3D. [б. в.], novembre 2020. http://dx.doi.org/10.31812/123456789/4410.
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In this paper, the possibilities of using augmented reality technology are analyzed and the software model of the solar system model is created. The analysis of the available software products modeling the solar system is carried out. The developed software application demonstrates the behavior of solar system objects in detail with augmented reality technology. In addition to the interactive 3D model, you can explore each planet visually as well as informatively – by reading the description of each object, its main characteristics, and interesting facts. The model has two main views: Augmented Reality and 3D. Real-world object parameters were used to create the 3D models, using the basic ones – the correct proportions in the size and velocity of the objects and the shapes and distances between the orbits of the celestial bodies.
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de Caritat, Patrice, Brent McInnes et Stephen Rowins. Towards a heavy mineral map of the Australian continent : a feasibility study. Geoscience Australia, 2020. http://dx.doi.org/10.11636/record.2020.031.
Texte intégralRésumé :
Heavy minerals (HMs) are minerals with a specific gravity greater than 2.9 g/cm3. They are commonly highly resistant to physical and chemical weathering, and therefore persist in sediments as lasting indicators of the (former) presence of the rocks they formed in. The presence/absence of certain HMs, their associations with other HMs, their concentration levels, and the geochemical patterns they form in maps or 3D models can be indicative of geological processes that contributed to their formation. Furthermore trace element and isotopic analyses of HMs have been used to vector to mineralisation or constrain timing of geological processes. The positive role of HMs in mineral exploration is well established in other countries, but comparatively little understood in Australia. Here we present the results of a pilot project that was designed to establish, test and assess a workflow to produce a HM map (or atlas of maps) and dataset for Australia. This would represent a critical step in the ability to detect anomalous HM patterns as it would establish the background HM characteristics (i.e., unrelated to mineralisation). Further the extremely rich dataset produced would be a valuable input into any future machine learning/big data-based prospectivity analysis. The pilot project consisted in selecting ten sites from the National Geochemical Survey of Australia (NGSA) and separating and analysing the HM contents from the 75-430 µm grain-size fraction of the top (0-10 cm depth) sediment samples. A workflow was established and tested based on the density separation of the HM-rich phase by combining a shake table and the use of dense liquids. The automated mineralogy quantification was performed on a TESCAN® Integrated Mineral Analyser (TIMA) that identified and mapped thousands of grains in a matter of minutes for each sample. The results indicated that: (1) the NGSA samples are appropriate for HM analysis; (2) over 40 HMs were effectively identified and quantified using TIMA automated quantitative mineralogy; (3) the resultant HMs’ mineralogy is consistent with the samples’ bulk geochemistry and regional geological setting; and (4) the HM makeup of the NGSA samples varied across the country, as shown by the mineral mounts and preliminary maps. Based on these observations, HM mapping of the continent using NGSA samples will likely result in coherent and interpretable geological patterns relating to bedrock lithology, metamorphic grade, degree of alteration and mineralisation. It could assist in geological investigations especially where outcrop is minimal, challenging to correctly attribute due to extensive weathering, or simply difficult to access. It is believed that a continental-scale HM atlas for Australia could assist in derisking mineral exploration and lead to investment, e.g., via tenement uptake, exploration, discovery and ultimately exploitation. As some HMs are hosts for technology critical elements such as rare earth elements, their systematic and internally consistent quantification and mapping could lead to resource discovery essential for a more sustainable, lower-carbon economy.
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Volunteer Kinematics and Reaction in Lateral Emergency Maneuver Tests. SAE International, novembre 2013. http://dx.doi.org/10.4271/2013-22-0013.
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It is important to understand human kinematics and muscle activation patterns in emergency maneuvers for the design of safety systems and for the further development of human models. The objective of this study was to quantify kinematic behavior and muscle activation in simulated steering tests in several realistic conditions. In total 108 tests were performed with 10 volunteers undergoing purely lateral maneuvers at 5 m/s2 deceleration or simulated lane change maneuvers at 5 m/s2 peak acceleration and peak yaw velocity of 25 °/s. Test subjects were seated on a rigid seat and restrained by a 4-point belt with retractor. Driver subjects were instructed to be relaxed or braced and to hold the steering wheel while passenger subjects were instructed to put their hands on their thighs. Subjects were instrumented with photo markers that were tracked with 3D high-speed stereo cameras and with electromyography (EMG) electrodes on 8 muscles. Corridors of head displacement, pitch and roll and displacement of T1, shoulder, elbow, hand and knee were created representing mean response and standard deviation of all subjects. In lane change tests for the passenger configuration significant differences were observed in mean peak of head left lateral displacement between the relaxed and the braced volunteers, i.e. 171 mm (σ=58, n=21) versus 121 mm (σ=46, n=17), respectively. Sitting in a relaxed position led to significantly lower muscle activity of the neck muscles. It was concluded that significantly more upper body motion and lower muscle activity was observed for relaxed subjects than for braced subjects.