Готові списки джерел за темами / VELOCITIE

Добірка наукової літератури з теми "VELOCITIE"

Автор: Grafiati

Опубліковано: 11 вересня 2023

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Статті в журналах з теми "VELOCITIE"

Deconto-Machado, A., R. A. Riffel, G. S. Ilha, S. B. Rembold, T. Storchi-Bergmann, R. Riffel, J. S. Schimoia, et al. "Ionised gas kinematics in MaNGA AGN." Astronomy & Astrophysics 659 (March 2022): A131. http://dx.doi.org/10.1051/0004-6361/202140613.

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Context. Feedback from active galactic nuclei (AGNs) in general seems to play an important role in the evolution of galaxies, although the impact of AGN winds on their host galaxies is still unknown in the absence of a detailed analysis. Aims. We aim to analyse the kinematics of a sample of 170 AGN host galaxies as compared to those of a matched control sample of non-active galaxies from the MaNGA survey in order to characterise and estimate the extents of the narrow-line region (NLR) and of the kinematically disturbed region (KDR) by the AGN. Methods. We defined the observed NLR radius (rNLR, o) as the farthest distance from the nucleus within which both [O III]/Hβ and [N II]/Hα ratios fall in the AGN region of the BPT diagram, and the Hα equivalent width was required to be larger than 3.0 Å. The extent of the KDR (rKDR, o) is defined as the distance from the nucleus within which the AGN host galaxies show a more disturbed gas kinematics than the control galaxies. Results. The AGN [O III]λ5007 luminosity ranges from 1039 to 1041 erg s−1, and the kinematics derived from the [O III] line profiles reveal that, on average, the most luminous AGNs (L[O III] > 3.8 × 1040 erg s−1) possess higher residual differences between the gaseous and stellar velocities and velocitie dispersions than their control galaxies in all the radial bins. Spatially resolved NLRs and KDRs were found in 55 and 46 AGN host galaxies, with corrected radii 0.2 < rKDR, c < 2.3 kpc and 0.4 < rNLR, c < 10.1 kpc and a relation between the two given by log rKDR, c = (0.53 ± 0.12) log rNLR, c + (1.07 ± 0.22), respectively. On average, the extension of the KDR corresponds to about 30% of that of the NLR. Assuming that the KDR is due to an AGN outflow, we have estimated ionised gas mass outflow rates that range between 10−5 and ∼1 M⊙ yr−1, and kinetic powers that range from 1034 to 1040 erg s−1. Conclusions. Comparing the power of the AGN ionised outflows with the AGN luminosities, they are always below the 0.05 LAGN model threshold for having an important feedback effect on their respective host galaxies. The mass outflow rates (and power) of our AGN sample correlate with their luminosities, populating the lowest AGN luminosity range of the correlations previously found for more powerful sources.

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Walker, G. A. H., J. Amor, S. Yang, and B. Campbell. "Precise Radial Velocities and Radial Velocity Standards." Symposium - International Astronomical Union 111 (1985): 587–89. http://dx.doi.org/10.1017/s0074180900079547.

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By imposing absorption lines of HF in stellar spectra we can measure changes in r.v. with a precision of ~10m/s from a single spectrum, provided stellar line profiles are not distorted by atmospheric motions. The precision of absolute radial velocities is currently limited to ~100m/s by knowledge of rest wavelengths. Representative results are presented from our three, active PRV programs: velocity variations of δ Scuti stars; a search for unseen companions to late-type stars; and routine observations of certain IAU velocity ‘standards’.

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Ehlen, Georg J., Hai Feng Wang, and Dieter M. Herlach. "Concentration Dependent Growth Velocities in Undercooled Al-Rich Al-Ni Alloy Systems." Materials Science Forum 790-791 (May 2014): 485–90. http://dx.doi.org/10.4028/www.scientific.net/msf.790-791.485.

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Dendrite growth velocity V as a function of undercooling on the Al-rich side of the Al-Ni system has recently been measured by electromagnetic levitation. The results have shown an anomalous behaviour, which so far cannot be theoretically described. The present work uses two simplified qualitative models of sharp interface theory, one of them treating the forming AlNi (B2) phase as a solid-solution, one treating it as an intermetallic phase, to investigate the influence of the phase diagram on the growth velocities. The results imply that the concentration dependent growth behaviour is a superposition of at least two effects: 1) A strong decrease of the total growth velocitiy level for increasing Al concentrations. 2) An increase of growth velocities with increase of Al concentration at medium and low undercoolings. The present work is able to explain the first effect, namely the concentration dependent reduction of velocities. Results are compared to experimental data. In both models the properties of the phase diagram lead to an increase of the constitutional undercooling ΔTc when the Al content increases. This reduces the fraction left for kinetic undercooling ΔTk, which is responsible for interface migration and which determines the growth velocity. Neither of the models can reproduce the second effect.

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Maybank, SJ. "Rigid velocities compatible with five image velocity vectors." Image and Vision Computing 8, no. 1 (February 1990): 18–23. http://dx.doi.org/10.1016/0262-8856(90)90051-6.

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Toldi, John L. "Velocity analysis without picking." GEOPHYSICS 54, no. 2 (February 1989): 191–99. http://dx.doi.org/10.1190/1.1442643.

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Conventionally, interval velocities are derived from picked stacking velocities. The velocity‐analysis algorithm proposed in this paper is also based on stacking velocities; however, it eliminates the conventional picking stage by always considering stacking velocities from the point of view of an interval‐velocity model. This view leads to a model‐based, automatic velocity‐analysis algorithm. The algorithm seeks to find an interval‐velocity model such that the stacking velocities calculated from that model give the most powerful stack. An additional penalty is incurred for models that differ in smoothness from an initial interval‐velocity model. The search for the best model is conducted by means of a conjugate‐gradient method. The connection between the interval‐velocity model and the stacking velocities plays an important role in the algorithm proposed in this paper. In the simplest case, stacking velocity is assumed to be equal to rms velocity. For the more general case, a linear theory is developed, connecting interval velocity and stacking velocity through the intermediary of traveltime. When applied to a field data set, the method produces an interval‐velocity model that explains the lateral variation in both stacking velocity and traveltime.

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Wendt, Anke S., Monzurul Alam, and Joao Paulo Castagnoli. "Sand injectite mapping using a resistivity-velocity transform function." Leading Edge 40, no. 3 (March 2021): 202–7. http://dx.doi.org/10.1190/tle40030202.1.

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Lack of resolution in the distribution of sand injectites in hydrocarbon fields is common and makes it difficult to predict drilling challenges and plan for optimum production. A practical workflow was developed that enables the distinction of shale and sand bodies by using a combination of low-resolution seismic data and high-resolution resistivity log data. Measured resistivity logs were used to predict synthetic velocity logs, which accurately match shale velocities and over- or underestimate velocities of other rock types. The synthetic velocity logs were spatially distributed in a 3D cube in order to predict synthetic velocities in between and away from the well locations. The 3D cube was representative of a field. It covered the interval from the seabed to below the reservoir. The spatial distribution was based on a geostatistical approach guided by measured seismic interval velocities. A residual velocity cube was calculated from the measured and synthetic velocities. The residual velocity cube produced near-zero velocities for shaly materials and velocity over- or underestimates for other rock types. Interpretation of the residual velocity cube required the identification of strong stratigraphic markers. The markers were removed from the residual cube by setting their specific layer velocities to 0 m/s. The final information stored in the residual velocity cube was then related to the over- or underestimated velocities in sand bodies.

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Du, Xue Jing, and Jin Peng Li. "Simulation of Pedestrian Colliding with Microbus Windshield." Key Engineering Materials 572 (September 2013): 574–77. http://dx.doi.org/10.4028/www.scientific.net/kem.572.574.

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In order to research the injury of pedestrian collided with microbus windshield, the finite element model of pedestrian and windshield are established based on the characteristics of pedestrian collision with microbus windshield in traffic accident to simulate the collision process by ANSYS/LS-DYNA. In the condition of different impact velocities, HIC, TTI and stress intensity of pedestrian are studied in simulation test. The results illustrate that with the impact velocitys increasing the original impact energy, stress intensity, acceleration, HIC, and TTI increase. Also, the collision time is prolonged. Collision in head, the head of pedestrian would suffer serious injury with more than 29 km/h impact velocity. The chest would suffer serious injury with more than 25 km/h impact velocity in condition of colliding on chest.

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Herman, Przemyslaw, and Krzysztof Kozlowski. "Velocity tracking control algorithm in terms of quasi-velocities." IFAC Proceedings Volumes 42, no. 13 (2009): 599–604. http://dx.doi.org/10.3182/20090819-3-pl-3002.00104.

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Cox, B. E., P. L. A. Winthaegen, D. J. Verschuur, and K. Roy-Chowdhury. "Common focus point velocity estimation for laterally varying velocities." First Break 19, no. 2 (February 2001): 75–83. http://dx.doi.org/10.1046/j.0263-5046.2001.00140.x.

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Blias, Emil. "Stacking velocities in the presence of overburden velocity anomalies." Geophysical Prospecting 57, no. 3 (May 2009): 323–41. http://dx.doi.org/10.1111/j.1365-2478.2008.00750.x.

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Дисертації з теми "VELOCITIE"

FRUSTAGLI, GIUSEPPE. "Exoplanets Characterization: from Ultra-short Period Planets to Ultra-hot Jupiters Atmospheres." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/311363.

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La scoperta di pianeti che orbitano intorno ad altre stelle è uno degli eventi più importanti nell'astrofisica galattica degli ultimi due decenni. Dalla scoperta del primo esopianeta nel 1995, il numero di esopianeti scoperti è cresciuto sempre più in fretta e attualmente conosciamo più di 4,000 pianeti, molto diversi per dimensioni e distanza dalla stella ospite e anche in fattori come temperatura, massa, densità. La diversità degli esopianeti è un fattore chiave per comprendere la formazione dei sistemi planetari e in particolare la formazione del Sistema Solare e del nostro pianeta, la Terra. Questo è il motivo per cui la scienza osservativa degli esopianeti si sta concentrando su due diversi obiettivi: i) la caratterizzazione degli esopianeti, nel tentativo di determinare il raggio, la massa, la densità e la composizione degli oggetti osservati e ii) la caratterizzazione delle loro atmosfere, stabilendo gli elementi che l'atmosfera di un pianeta può supportare e i meccanismi che guidano i processi atmosferici. Caratterizzazione degli Esopianeti La fotometria, con il metodo dei transiti si è rivelato senza dubbio il metodo di scoperta di esopianeti con il maggior successo. La forza di questo metodo è il numero di parametri che possono essere ottenuti osservando il transito dei pianeti, soprattutto in combinazione con le osservazioni di velocità radiale (VR). In questo contesto, uno dei gruppi più prolifici è il Consorzio GTO di HARPS-N, che sfrutta l'alta risoluzione e l'estrema stabilità dello spettrografo HARPS-N, installato al Telescopio Nazionale Galileo, per caratterizzare e scoprire esopianeti combinando il metodo dei transiti e quello delle velocità radiali. Come collaboratore di questo gruppo, ho studiato un pianeta candidato scoperto dalla Campagna 16 della missione K2, HD 80653 b, una super-Terra che transita davanti alla sua stella con un periodo orbitale molto breve, e ho usato le VR HARPS-N per caratterizzarlo, ottenendo la sua massa e definendone la densità. Il pianeta appartiene ad una particolare classe di esopianeti: i pianeti a periodo ultra-corto, oggetti che orbitano intorno alle loro stelle con periodi estremamente brevi, più piccoli di due raggi terrestri e con composizioni simili a quella terrestre. Caratterizzazione di Atmosfere I gioviani ultra-caldi sono laboratori eccellenti per lo studio delle atmosfere esoplanetarie. Il sodio, per la sua grande sezione d'urto e per il fatto che le sue righe spettrali principali si trovano nel range spettrale della maggior parte degli spettrografi, è l'elemento più studiato, ma lo studio di nuove righe spettrali è cominciato. Righe del ferro, del titanio, del magnesio, ma anche tracce di cromo, scandio e ittrio sono state trovate negli spettri di trasmissione ad alta risoluzione dei pianeti più caldi. I due gioviani ultra-caldi KELT-9 b e KELT-20 b sono stati osservati dal programma atmosfere del gruppo italiano Global architecture of Planetary Systems (GAPS). Come membro del gruppo ho potuto esplorare più in dettaglio il metodo della spettroscopia in transito, creando due diverse routine per la caratterizzazione delle atmosfere. Il primo metodo segue approcci già utilizzati in precedenza, ma è in grado di rilevare righe spettrali deboli come quelle del magnesio, sommandole nello spazio delle velocità. Usando questo approccio ho analizzato gli spettri ad alta risoluzione di KELT-9 b e KELT-20 b e ho ottenuto i loro spettri di trasmissione, rilevando un assorbimento significativo per Na, H, Fe e Mg I. Il secondo metodo estrae gli spettri di trasmissione ad alta risoluzione e li cross-correla con modelli teorici di spettri di trasmissione. Analizzando gli spettri di KELT-20 b e utilizzando la cross-correlazione ho potuto confermare la presenza di Fe I, Fe II e Na I, trovate da analisi precedenti di altri gruppi di ricerca.
The discovery of planets orbiting around stars other than the Sun is by far the most relevant event in the galactic astrophysics of the last two decades. Since the discovery of the first exoplanet in 1995, the number of exoplanets discovered grew fast and we currently know more than 4,000 exoplanets, very diverse in dimension and distance from parent stars and also in factors as temperature, mass, density. The diversity of exoplanets is a key factor to understand more about the formation of planetary systems and in particular the formation of the Solar System and our planet, the Earth. This is the reason why observational exoplanetary science is currently focusing on two different fields: i) the characterization of exoplanets, trying to determine the radius, the mass, the density and the bulk composition of the objects observed, and ii) the characterization of their atmospheres, establishing the elements that the atmosphere of a planet supports and the mechanisms that drive the atmospheric processes. Characterization of Exoplanets Photometry with the transit method has arguably been the most successful exoplanet discovery method to date. The method’s strength is the rich set of parameters that can be obtained from transiting planets, in particular in combination with RV observations. In this framework, one of the most prolific groups is the HARPS-N Guaranteed Time Observations (GTO) Consortium, that makes use of the high resolution (R = 115,000) and extreme stability of the HARPS-N spectrograph, installed on the Telescopio Nazionale Galileo (TNG), to characterize and discover exoplanets by combining transits and RV methods. As a collaborator of this group, I studied a candidate planet discovered by K2 Campaign 16, HD 80653 b, a super-Earth planet transiting the star on a short period orbit, and used HARPS-N RV data to characterize it, finding its mass and defining its bulk density. It belongs to a peculiar class of exoplanets: the Ultra-Short Period (USP) planets, objects that orbit their stars with extremely short periods, smaller than about 2 Earth Radii and compositions similar to that of the Earth. Characterization of Atmospheres Ultra-hot Jupiters are excellent laboratories for the study of exoplanetary atmospheres. Sodium, due to its large cross-section and to the fact it is in the wavelength range of most optical spectrographs, is the most studied element, but new interesting features begin to be analyzed. Lines of iron, titanium, magnesium, but also chromium, scandium and yttrium have been found in the high resolution transmission spectra of the hottest planets. The two ultra-hot Jupiters KELT-9 b and KELT-20 b were observed in the framework of the Global architecture of Planetary Systems (GAPS) Atmosphere program. I explored more in detail the transit spectroscopy method, creating two different routines for atmosphere characterization. The first routine follows previous approaches for high-resolution spectroscopy, but is able to detect weak spectral lines such as those of magnesium, by co-adding the lines in the velocities space. Using this procedure, I analyzed the high-resolution spectra of KELT-9 b and KELT-20 b, obtaining their transmission spectra and detecting significant absorption for Na, H, Fe and Mg I. The second routine extracts the high-resolution transmission spectra of exoplanets and cross-correlates them with theoretical transmission spectra models. I analyzed the high-resolution spectra of KELT-20 b and with the cross-correlation technique I confirmed previous detections of Fe I, Fe II, and Na I.

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Kennedy, Michael David Joseph. "A comparison of critical velocity estimates to actual velocities in predicting simulated rowing performance." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq22611.pdf.

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Hashim, Muazzam Ali. "Investigating subsurface heterogeneities and its impact on the variation in interval velocities : implications to velocity modelling in the Bredasdorp basin." Thesis, University of the Western Cape, 2015. http://hdl.handle.net/11394/5328.

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>Magister Scientiae - MSc
Velocity modelling forms an integral part of the seismic interpretation process initially completed in two-way time. In order for a representative depth conversion, it is obligatory to construct a velocity model that serves the bridge between velocity and respective two-way time. This study deals with the investigation of subsurface heterogeneities and its impact on the variation of velocities. Interpretation of time domain reflection data results in one or more seismic horizons, however these horizons should represent the variation in subsurface geology as a result of acoustically different layers displaying varying reflection amplitudes. The purpose of this study was fulfilled by examining the variation of these velocities in relation to the geology and its significance towards building a velocity model. It is evident that complexities, such as an existing heterogeneous subsurface is present in the study area. Using velocities only considered at formation well tops, as a result, does not completely honour the variation in these velocities. The velocity profile as calculated from the sonic log was characterized into zones representing unique velocity trends. The analyses to understand the impact of subsurface heterogeneities on the velocities was completed by the application of seismic facies analysis which entailed the study of the seismic reflector patterns and amplitudes; a study of the lithologies present and the generation of mineral plots using available wireline logs, all of which in close relation to the variation in velocities. The characterized zones, as a result have shown that shaly sediments are typically associated with higher velocities (~2800 – 4600m/s) compared to sandstones of lower densities. Mineral plots however, have also indicated that where quartz minerals were present (specifically zone L), sandstones as a result have shown higher velocities (~4800m/s) as compared to the shales (~3600m/s). These higher velocities are also associated with more organised seismic reflectors with brighter amplitudes and strong contrasts in acoustic impedance as shown by the seismic. Uniform velocities were observed in zones such as zone Ia, typically associated with a low acoustic impedance contrast and minimal variation in its lithological make-up. The integrated investigation of subsurface heterogeneities has shown that velocities vary to a substantial degree as a result of existing subsurface heterogeneities. The variation of these velocities are hence significant enough that it should be considered when constructing a velocity model which aims to respect the geology of the study area. The result of understanding the relation between the geology and resultant velocities may prove to advance the results of the velocity model in a manner that it is more complete and representative of the subsurface.

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Van, Riper Steven G. "Investigation of increased forward flight velocities of helicopters using second harmonic control and reverse velocity rotor concept." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FVanRiper.pdf.

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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, December 2003.
Thesis advisor(s): E. Roberts Wood, Raymond Shreeve. Includes bibliographical references (p. 145-146). Also available online.

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Allen, G. F. "Interval velocities from moveout velocities over a seismic reflection survey area." Thesis, University of Leicester, 1985. http://hdl.handle.net/2381/33751.

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Moveout velocities sampled frequently along seismic horizons on a selection of seismic lines are used to derive interval velocities in an 'inversion' algorithm developed from work published by Hubral. This inversion is based on zero-offset raytrace modelling in a simplistic local ground model. The 'Hubral algorithm' is incorporated into a database which allows spatial smoothing of velocities. The spatial consistency of derived interval velocities can then be assessed by reference to mis-ties at line intersections, while interval velocities from well data can be used to check their validity. These principles have been used to derive interval velocities both from real data and from 'synthetic' data generated by common mid-point raytracing over schematic ground models. The latter study reveals that the procedure performs well if the local subsurface sampled by the CMP gather conforms approximately to the simplistic ground model assumed by the Hubral algorithm. The method is unsuitable in areas of faulting and interval velocity heterogeneity, and may yield spurious results over fold axes. Application of the procedure to real data indicates that it is generally desirable to smooth both moveout velocities before inversion and interval velocities after inversion. Comparison with well information shows that interval velocities derived by the Hubral algorithm are consistently higher than those measured from calibrated velocity logs. This observation is disturbing, since the derived interval velocities require a correction if they are to be used for depth conversions, but the discrepancy cannot be explained by ray theoretical considerations. No advantage appears to be gained by the 'layer-by-layer' mode of inversion over the 'direct' inversion, despite the greater potential for error propagation anticipated in the latter. Further work on different data sets is required to justify general use of the layer-by-layer mode of inversion.

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Marshall, Stephen P. "Measuring laminar burning velocities." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:81ea0ed8-3abd-4192-86ef-67bd5581c325.

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The laminar burning velocity of a fuel is the rate of normal propagation of a 1D flame front relative to the movement of the unburned gas. This is a fundamental property of a fuel that affects many aspects of its combustion behaviour. Experimental values are required to validate kinetic simulations, and also to provide input for models of flashback, minimum ignition energy and turbulent combustion. Burning velocity affects burn duration and consequently power output in spark ignition engines. Burning velocities are affected by pressure, temperature, equivalence ratio, residuals, additives, and stretch rates. The constant volume vessel has been used as it is considered both the most versatile and accurate method of measuring laminar burning velocities. An existing combustion vessel and oven were refurbished and new systems built for fuel injection, ignition, experiment control, data acquisition and high speed schlieren photography. An existing multi-zone model was used to allow calculation of burning velocity from pressure and schlieren data, allowing the user to select data uncorrupted by heat transfer or cellularity. A twelve term correlation for burning velocity was validated using methane modelling data. The chosen data from all the experiments was then fitted to the correlation. Methane, n-butane, n-heptane, iso-octane, toluene, ethylbenzene and ethanol were tested over a wide range of initial pressures (0.5, 1, 2 and 4 barA), temperatures (289-450 K) and equivalence ratios (0.7-1.4). For liquid fuels, tests with real residuals at mole fractions of up to 0.3 were also conducted. Stoichiometric mixture tests were performed at two initial temperatures (380 and 450 K) and the same four initial pressures. For mixtures of iso-octane and ethylbenzene, percentage volumes of 12.5, 25, 50 and 75% iso-octane were tested. It was found that the the percentage of iso-octane affected burning velocity non-linearly. For iso-octane/ethanol, a single 50:50% mixture was tested.

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Kratochvíl, Pavel. "Analýza seismického rychlostního pole." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220661.

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Seismic velocities are an important prerequisite for seismic processing as a method for hydrocarbons accumulations detection. Seismic velocities are often displayed for mutual comparing, improvement checking, they are filtrated and recalculated for its different characteristic determination. This work deals with basic seismic propagation laws, the meaning of velocities in different stages of seismic processing and this theoretical background is followed by a proposition of method for calculating and displaying of stack velocities.

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Lewis, Braxton V. "Effects of 0[degree] cross draft velocity and the presence of a table and manikin on midline velocities in front of a rectangular capture hood." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11147.

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Thesis (M.S.)--West Virginia University, 2010.
Title from document title page. Document formatted into pages; contains ix, 74 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 53-55).

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Seabroke, George Michael. "Probing the Milky Way galaxy through thick and thin (discs and halo) with the CORrelation RAdial VELocities (CORAVEL) and the RAdial velocity experiment (RAVE) surveys." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612308.

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Ehwald, Lena Elisa. "Seasonal Velocities on Nordenskiöldbreen, Svalbard." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-296682.

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Global warming leads to increased precipitation in the Arctic, as warmer air can carry more moisture. The consequence is that many arctic glaciers get steeper slopes over time as increased melt at their lower part causes thinning and increased solid precipitation in their upper regions leads to thickening of the glacier. Ice flow of glaciers is strongly controlled by the surface slope, where steeper slopes leads to increased ice flow. An altered flow regime of the glaciers can lead to unpredicted contributions to sea-level changes as more glacier ice is delivered to lower regions and eventually to the sea through calving of melt- runoff. Long-term measurements of ice-flow velocities are therefore crucial to receive a better understanding of how glaciers respond to climate changes in a temporal and spatial scale. This study investigates ice flow velocities measured over a period of 10 years between 2006 and 2015 on Nordenskiöldbreen, Svalbard. The poly-thermal outlet glacier is centrally located on Spitsbergen; the main island of the Svalbard archipelago (74N°,10°E /81N°,35°E). Ice-flow velocities are measured continuously using stand-alone single-frequency GPS receivers attached to 8 metal stakes along the central flow line of Nordenskiöldbreen. The Institute for Marine and Atmospheric research in Utrecht, the Netherlands (IMAU) has developed such GPS units to measure ice-flow velocities at low costs and all year-round. Ice flow velocities at the central-flow line of Nordenskiöldbreen for the period 2006-2016 are estimated to be between 40 and 60 m a-1. Results show that maximum ice flow velocities can reach up to 80 m a-1 and occur mainly in the beginning of July. The highest annual averaged velocity of 53.88 m a-1 was measured during summer 2014. Averaged ice-flow velocities show an increasing trend of about 1.78 m a-1 during summer seasons. Results are further compared with mass balance observations and temperature records to analyze how glacier systems respond to climate changes.
Klimatuppvärmningen bidrar till att glaciärer blir tunnare och smälter snabbare. Ett varmare klimat är också orsaken till att snöfall ökar då varmare luft kan transportera mer fuktighet. Konsekvensen blir att glaciärer i arktiska områden får brantare sluttningar. Brantare sluttningar leder sedan till att glaciärer rör sig snabbare. Om glaciärer plötsligt rör sig snabbare uppstår möjligheten att havsnivån också stiger snabbare. Uppsatsen undersöker is-hastigheten från Nordenskiöldbreen. Nordenskiöldbreen är en glaciär på Spetsbergen, Svalbard som går ut i Adolfbukta innerst Billesjorden. Hastigheten uppmättes med hjälp av 13 GPS-stationer på glaciärens yta, placerade mellan 800 och 1200 meter över havsnivån. GPS-stationerna är utvecklade av Institut för Marin- och Atmosfär-undersökningar i Utrecht, Holland (IMAU) för att mäta glaciärens hastighet året runt till låga kostnader. Sedan 1997 har Institutionen för geovetenskaper vid Uppsala Universitet utfört flera mätningar på Nordenskiöldbreen för att mäta massbalans, isrörelse och miljöförändringar. Massbalans mätningar har visat att glaciären fick brantare sluttningar över den senaste tio-års perioden. Uppsatsen analyserar trenden för isrörelse vid Nordenskiöldbreen över de senaste tio åren. Dessutom är resultanterna jämförda med massbalans-analyser och temperaturmätningar från Svalbard Flygplats. Jämförelsen hjälper att förstå hur glaciärens system reagerar på klimatförändringar. De uppskattade hastighetsresultaten visar att Nordenskiöldbreen rör sig med en medelhastighet av 45-53 meter per år. Isrörelse kan nå upp till 80 meter per år och är främst förekommande under juli månad när temperaturen är hög. Detta producerar då mer smältvatten vilket driver upp vattentrycket vid glaciärens botten och leder till basal glidning.

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Книги з теми "VELOCITIE"

Andrew, Joron, ed. Terminal velocities. Berkeley CA: Pantograph Press, 1993.

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Robinson, Ron. Airgun velocities! 2nd ed. [Albuquerque, N.M.] (700 Monte Alto N.E., Albuquerque 87123): R. Robinson, 1990.

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Davis, Philip A. G., and Latham David W, eds. Stellar radial velocities. Schenectady, N.Y: L. Davis Press, 1985.

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Koontz, Dean R. Velocity. London: Harper, 2011.

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Velocity. London: Scholastic, 2015.

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Krygowski, Nancy. Velocity. Pittsburgh, Pa: University of Pittsburgh Press, 2007.

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Koontz, Dean R. Velocity. New York: Bantam Books, 2005.

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Krygowski, Nancy. Velocity. Pittsburgh, PA: University of Pittsburgh Press, 2008.

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Velocity. New York: Bantam Books, 2012.

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McCloy, Kristin. Velocity. New York: Random House, 1988.

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Walker, G. A. H., J. Amor, S. Yang, and B. Campbell. "Precise Radial Velocities and Radial Velocity Standards." In Calibration of Fundamental Stellar Quantities, 587–89. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5456-4_81.

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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Thermal Geometric Phases: Exceptional Point Encirclement." In Transformation Thermotics and Extended Theories, 291–304. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_21.

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AbstractIn this chapter, we experimentally demonstrate that the geometric phase can also emerge in a macroscopic thermal convection-conduction system. Following Li et al. [Science 364, 170–173 (2019)], we study two moving rings with equal-but-opposite velocities, joined together by a stationary intermediate layer. We first confirm an exceptional point of velocity that separates a stationary temperature profile and a moving one. We then investigate a cyclic path of time-varying velocity containing the exceptional point, and an extra phase difference of $$\pi $$ π appears (say, the geometric phase). These results broaden the scope of the geometric phase and provide insights into the thermal topology.

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Cordier, Jean-Pierre. "Velocities in Seismic Reflection. Definitions. Principles of Velocity Analysis." In Velocities in Reflection Seismology, 47–58. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3641-1_6.

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Cordier, Jean-Pierre. "Basic Ideas on the Propagation of Seismic Waves." In Velocities in Reflection Seismology, 1–5. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3641-1_1.

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Cordier, Jean-Pierre. "Calculation of Interval Velocities." In Velocities in Reflection Seismology, 101–14. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3641-1_10.

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Cordier, Jean-Pierre. "Velocity Analysis. Principles. Examples." In Velocities in Reflection Seismology, 115–25. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3641-1_11.

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Cordier, Jean-Pierre. "Choice of Parameters in Velocity Analysis." In Velocities in Reflection Seismology, 126–28. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3641-1_12.

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Cordier, Jean-Pierre. "Other Presentations of Velocity Analyses. Analyses along Horizons. Constant Velocity Stacks. Rapid Determination of Interval Velocities: G.S.I. (Geophysical Service Inc.) Graphical Method." In Velocities in Reflection Seismology, 129–34. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3641-1_13.

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Cordier, Jean-Pierre. "Interpretation and Utilisation of Velocity Analyses. Accuracy Required and Causes of Inaccuracy. Advice on Positioning and Interpretation of Velocity Analyses." In Velocities in Reflection Seismology, 135–54. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3641-1_14.

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Cordier, Jean-Pierre. "Influence of the “Velocity” Parameter on the Process of Migration of Seismic Sections." In Velocities in Reflection Seismology, 155–67. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3641-1_15.

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Тези доповідей конференцій з теми "VELOCITIE"

Øverås, R., V. Kalashnikova, S. Guidard, and I. Meisingset. "Construction Technique Of High Resolution Velocity Field - New Attribute For Seismic Interpretation." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800001.

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Rudling, C. J., A. Riaz, and J. Smith. "Azimuthal Anisotropy Resolved By Tilted Orthorhombic Tomography." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800002.

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Meisingset, I., J. Hubred, and D. Krasova. "Understanding Delta Anisotropy On A Regional Scale." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800003.

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Hart, M. J., J. Sheng, S. Baldock, and J. Mao. "FWI Velocity Model Building Experiences." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800004.

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Lewis, O. J., S. Way, G. Apeland, P. Smith, H. Veire, J. R. Granli, L. M. Moskvil, and N. Stevens. "Earth Model Building With Full-Waveform Inversion - A Case Study From A Shallow Reservoir In The Barents Sea." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800005.

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Gupta, S., A. Cooke, M. Steiger-Jarvis, J. Bailey, and A. Sellars. "Optimizing The Model Building Approach Using Full-Waveform Inversion And Multilayer Reflection Tomography - A North Sea Workflow." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800006.

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Jones, I. F., J. Singh, P. Cox, M. Warner, C. Hawke, D. Harger, and S. Greenwood. "High Resolution Velocity Estimation Using Refraction And Reflection Fwi - The Fortuna Region, Offshore Equatorial Guinea." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800007.

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Roth, T., T. Nangoo, N. Shah, M. Riede, C. Henke, and M. Warner. "Improving Seismic Image With High Resolution Velocity Model From AWI Starting With 1D Initial Model - Case Study Barents Sea." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800008.

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Meisingset, I., J. Hubred, and D. Krasova. "High Quality Regional Velocity Modelling For Depth Conversion." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800009.

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Fonseca, J. S., L. Teixeira, A. Maul, P. Barros, F. Borges, J. Boechat, and M. González. "Modelling Geological Layers Into New Velocity Models For Seismic Migration Process - A Brazilian Pre-Salt Case." In First EAGE/PESGB Workshop on Velocities. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201800010.

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Gaines, Roger, Stephen Sanborn, William McAnally, and Christopher Wallen. Mississippi River Adaptive Hydraulics model development and evaluation, Commerce to New Madrid, Missouri, Reach. Engineer Research and Development Center (U.S.), January 2020. http://dx.doi.org/10.21079/11681/39519.

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A numerical, two-dimensional hydrodynamic model of the Mississippi River, from Thebes, IL, to Tiptonville, TN (128 miles/206 km), was developed using the Adaptive Hydraulics model. The study objective assessed current patterns and flow distributions and their possible impacts on navigation due to Birds Point New Madrid Floodway (BPNMF) operations and the Len Small (LS) levee break. The model was calibrated to stage, discharge, and velocity data for the 2011, 2015–2016, and 2017 floods. The calibrated model was used to run four scenarios, with the BPNMF and the LS breach alternately active/open and inactive/closed. Effects from the LS breach being open are increased river velocities upstream of the breach, decreased velocities from the breach to Thompson Landing, no effects on velocity below the confluence, and cross-current velocities greater than 3.28 ft/s (1.0 m/s) within 1186.8 ft (60 m) of the bankline revetment. Effects from BPNMF operation are increased river velocities above the confluence, decreased velocities from the BPNMF upper inflow crevasse (Upper Fuseplug) to New Madrid, cross-current velocities greater than 1.5 ft/s (0.5 m/s) only near the right bank where flow re-enters the river from the BPNMF lower inflow/outflow crevasse Number 2 (Lower Fuseplug) and St. Johns Bayou.

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Eckert, Richard. PR-186-184509-R01 Guideline for Erosional Velocity. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), February 2020. http://dx.doi.org/10.55274/r0011655.

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A guideline to determine erosional velocity limits for liquid hydrocarbon transmission pipelines was developed based on a multi-analytical probabilistic approach that integrated results from two erosional models: DNV GL RP-O501 and University of Tulsa SPPS v5.3. The guideline uses a simple classification tree model as first approach to provide conservative erosional velocities with a minimum amount of input data. The guideline also presents an alternative probabilistic approach for determining erosional velocities when the classification tree cannot be used, e.g., when there is too much data uncertainty or the erosional velocity limit (which is highly conservative) is lower than the current or expected liquid velocity in the pipeline. The database table is available for download. The link is https://www.prci.org/Research/DesignMaterialsConstruction/DMCProjects/FLOW-1-2/142187/181060.aspx This report has a related webinar.

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McInerney, Michael, Matthew Brenner, Sean Morefield, Robert Weber, and John Carlyle. Acoustic nondestructive testing and measurement of tension for steel reinforcing members. Engineer Research and Development Center (U.S.), October 2021. http://dx.doi.org/10.21079/11681/42181.

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Many concrete structures contain internal post-tensioned steel structural members that are subject to fracturing and corrosion. The major problem with conventional tension measurement techniques is that they use indirect and non-quantitative methods to determine whether there has been a loss of tension. This work developed an acoustics-based technology and method for making quantitative tension measurements of an embedded, tensioned steel member. The theory and model were verified in the laboratory using a variety of steel rods as test specimens. Field tests of the method were conducted at three Corps of Engineers dams. Measurements of the longitudinal and shear velocity were done on rods up to 50 ft long. Not all rods of this length were able to be measured and the quality and consistency of the signal varied. There were fewer problems measuring the longitudinal velocity than shear velocity. While the tension predictions worked in the laboratory tests, the tension could not be accurately calculated for any of the field sites because researchers could not obtain the longitudinal or shear velocities in an unstressed state, or precise measurements of the longitudinal and shear velocities due to the unknown precise length of the rods in the tensioned state.

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McKnight, C., David May, and Keaton Jones. Numerical analysis of dike effects on the Mississippi River using a two-dimensional Adaptive Hydraulics model (AdH). Engineer Research and Development Center (U.S.), November 2022. http://dx.doi.org/10.21079/11681/46120.

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This report describes the hydraulic effects of dikes on water surface elevation (WSE) and velocities in the Mississippi River near Vicksburg, MS, from Interstate 20 to Highway 80 using a previously calibrated 2D Adaptive Hydraulics numerical model. Dike heights and their associated hydraulic roughness values were varied to quantify the overall effects of adjustments to dike fields. Steady flows characterized as low, medium, and high conditions were simulated. The WSE and velocity difference plots were generated to illustrate the hydraulic effects on the river under all scenarios discussed above. Overall, the dike adjustments had negligible impacts on WSEs and showed minimal effects on velocities on a system-wide scale.

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Rahmani, Mehran, and Manan Naik. Structural Identification and Damage Detection in Bridges using Wave Method and Uniform Shear Beam Models: A Feasibility Study. Mineta Transportation Institute, February 2021. http://dx.doi.org/10.31979/mti.2021.1934.

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This report presents a wave method to be used for the structural identification and damage detection of structural components in bridges, e.g., bridge piers. This method has proven to be promising when applied to real structures and large amplitude responses in buildings (e.g., mid-rise and high-rise buildings). This study is the first application of the method to damaged bridge structures. The bridge identification was performed using wave propagation in a simple uniform shear beam model. The method identifies a wave velocity for the structure by fitting an equivalent uniform shear beam model to the impulse response functions of the recorded earthquake response. The structural damage is detected by measuring changes in the identified velocities from one damaging event to another. The method uses the acceleration response recorded in the structure to detect damage. In this study, the acceleration response from a shake-table four-span bridge tested to failure was used. Pairs of sensors were identified to represent a specific wave passage in the bridge. Wave velocities were identified for several sensor pairs and various shaking intensities are reported; further, actual observed damage in the bridge was compared with the detected reductions in the identified velocities. The results show that the identified shear wave velocities presented a decreasing trend as the shaking intensity was increased, and the average percentage reduction in the velocities was consistent with the overall observed damage in the bridge. However, there was no clear correlation between a specific wave passage and the observed reduction in the velocities. This indicates that the uniform shear beam model was too simple to localize the damage in the bridge. Instead, it provides a proxy for the overall extent of change in the response due to damage.

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Ratigan. L52293 Brine String Integrity Survey and Model Evaluation. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2009. http://dx.doi.org/10.55274/r0010206.

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Brine strings are essential components of both natural gas and liquid hydrocarbon storage caverns. Both the natural gas and liquid hydrocarbon storage industries are well aware that a limit exists for the fluid velocity in the injection tubulars in their storage caverns. If the brine injection or brine withdrawal velocity is gradually increased, eventually, the hanging tubular will experience flow-induced vibration, resulting in the potential for the hanging tubulars to bend and/or break. Additionally, in both types of hydrocarbon storage, salt falls can impact the brine string integrity.Result: The magnitude of the velocity limit for flow-induced vibration of the hanging tubulars in salt caverns is not known. In the absence of a clearly defined method for determining the maximum allowable fluid velocities in the hanging tubulars, much of industry has attempted to adopt a conservative maximum flow velocity based on "industry experience". Sometimes this works and sometimes it does not. The objective of this project is to better define the causes of brine string failure and failure mitigation technologies. The project (1) compiled case histories of successful brine string installations as well as brine string failures in solution mining, liquid hydrocarbon storage, and gas cavern dewatering; (2) evaluated case histories with models (proposed in the literature) for brine strings that have not failed as well as brine strings that have experienced failure; and (3) developed recommendations for maximizing brine string integrity.

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Raubenheimer, Britt. Swashzone Fluid Velocities. Fort Belvoir, VA: Defense Technical Information Center, September 2001. http://dx.doi.org/10.21236/ada627488.

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Raubenheimer, Britt. Swashzone Fluid Velocities. Fort Belvoir, VA: Defense Technical Information Center, September 2003. http://dx.doi.org/10.21236/ada630081.

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Raubenheimer, Britt. Swashzone Fluid Velocities. Fort Belvoir, VA: Defense Technical Information Center, September 2004. http://dx.doi.org/10.21236/ada630116.

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Ziegler, Nancy, Nicholas Webb, Adrian Chappell, and Sandra LeGrand. Scale invariance of albedo-based wind friction velocity. Engineer Research and Development Center (U.S.), May 2021. http://dx.doi.org/10.21079/11681/40499.

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Obtaining reliable estimates of aerodynamic roughness is necessary to interpret and accurately predict aeolian sediment transport dynamics. However, inherent uncertainties in field measurements and models of surface aerodynamic properties continue to undermine aeolian research, monitoring, and dust modeling. A new relation between aerodynamic shelter and land surface shadow has been established at the wind tunnel scale, enabling the potential for estimates of wind erosion and dust emission to be obtained across scales from albedo data. Here, we compare estimates of wind friction velocity (u*) derived from traditional methods (wind speed profiles) with those derived from the albedo model at two separate scales using bare soil patch (via net radiometers) and landscape (via MODIS 500 m) datasets. Results show that profile-derived estimates of u* are highly variable in anisotropic surface roughness due to changes in wind direction and fetch. Wind speed profiles poorly estimate soil surface (bed) wind friction velocities necessary for aeolian sediment transport research and modeling. Albedo-based estimates of u* at both scales have small variability because the estimate is integrated over a defined, fixed area and resolves the partition of wind momentum be-tween roughness elements and the soil surface. We demonstrate that the wind tunnel-based calibration of albedo for predicting wind friction velocities at the soil surface (us*) is applicable across scales. The albedo-based approach enables consistent and reliable drag partition correction across scales for model and field estimates of us* necessary for wind erosion and dust emission modeling.

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