Bibliografie tematiche / Surface velocity field

Letteratura scientifica selezionata sul tema "Surface velocity field"

Autore: Grafiati

Pubblicato: 25 maggio 2024

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Articoli di riviste sul tema "Surface velocity field":

Yuan, Xinzhe, Jian Wang, Bing Han e Xiaoqing Wang. "Study on the Elimination Method of Wind Field Influence in Retrieving a Sea Surface Current Field". Sensors 22, n. 22 (14 novembre 2022): 8781. http://dx.doi.org/10.3390/s22228781.

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An along-the-track interferometric synthetic aperture radar (ATI-SAR) system can estimate the radial velocity of a moving target on the ground and on a sea surface current. This acquires the interference phase by combining two composite SAR images obtained by two antennas spatially separated along the direction of movement of the platform. The key to retrieving the sea surface current is to remove the interference of sea surface waves, wind-generated current, and Bragg phase velocity in the interference Doppler velocity. Previous methods removed the surface waves, Bragg phase velocity, and other interferences based on externally-assisted wind fields (e.g., ECMWF), using the M4S or other models. However, the wind fields obtained from ECMWF and other external information are often average results of a large temporal and spatial scale, while the images obtained from SAR are high-resolution images of sea surface transients, which are quite different in time and space. This paper takes the SAR image data of the Gaofen-3 satellite as the research object and employs an SAR-based wind field retrieval method to obtain an SAR-observed transient wind field. Combined with the CDOP model, the interference of Doppler velocities, such as the sea surface wave, wind-generated current, and Bragg wave phase velocity, was calculated and subtracted from the Doppler velocity, to obtain the sea surface velocity result. Then, the current field measured by the shore-based HF radar was compared with that obtained by correcting the ATI Doppler velocity based on the SAR retrieved wind field and the ECMWF wind field. The comparison of results indicated that the wind field correction result based on the SAR retrieved wind field was closer to the current field measured by the shore-based HF radar than the wind field correction result based on the ECMWF wind field.

Gonçalves, Rafael C., Mohamed Iskandarani, Tamay Özgökmen e W. Carlisle Thacker. "Reconstruction of Submesoscale Velocity Field from Surface Drifters". Journal of Physical Oceanography 49, n. 4 (aprile 2019): 941–58. http://dx.doi.org/10.1175/jpo-d-18-0025.1.

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AbstractThe extensive drifter deployment during the Lagrangian Submesoscale Experiment (LASER) provided observations of the surface velocity field in the northern Gulf of Mexico with high resolution in space and time. Here, we estimate the submesoscale velocity field sampled by those drifters using a procedure that statistically interpolates these data both spatially and temporally. Because the spacing of the drifters evolves with the flow, causing the resolution that they provide to vary in space and time, it is important to be able to characterize where and when the estimated velocity field is more or less accurate, which we do by providing fields of interpolation errors. Our interpolation uses a squared-exponential covariance function characterizing correlations in latitude, longitude, and time. Two novelties in our approach are 1) the use of two scales of variation per dimension in the covariance function and 2) allowing the data to determine these scales along with the appropriate amplitude of observational noise at these scales. We present the evolution of the reconstructed velocity field along with maps of relative vorticity, horizontal divergence, and lateral strain rate. The reconstructed velocity field exhibits horizontal length scales of 0.4–3.5 km and time scales of 0.6–3 h, and features with convergence up to 8 times the planetary vorticity f, lateral strain rate up to 10f, and relative vorticity up to 13f. Our results point to the existence of a vigorous and substantial ageostrophic circulation in the submesoscale range.

Lloyd, Peter M., Peter K. Stansby e David J. Ball. "Unsteady surface-velocity field measurement using particle tracking velocimetry". Journal of Hydraulic Research 33, n. 4 (luglio 1995): 519–34. http://dx.doi.org/10.1080/00221689509498658.

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Arnold, E., T. Letavic e S. Herko. "High-field electron velocity in silicon surface-accumulation layers". IEEE Electron Device Letters 20, n. 9 (settembre 1999): 490–92. http://dx.doi.org/10.1109/55.784462.

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Melville, W. K., e Ronald J. Rapp. "The surface velocity field in steep and breaking waves". Journal of Fluid Mechanics 189 (aprile 1988): 1–22. http://dx.doi.org/10.1017/s0022112088000898.

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Coincident simultaneous measurements of the surface displacement and the horizontal velocity at the surface of steep and breaking waves are presented. The measurements involve a novel use of laser anemometry at the fluctuating air-water interface and clearly show the limitations of surface displacement measurements in characterizing steep and breaking wave fields. The measurements are used to examine the evolution of the surface drift velocity, spectra, wave envelopes, and forced long waves in unstable deep-water waves. Preliminary results of this work were reported by Melville & Rapp (1983).

Kim, Joon Hyun, e Joo-Hyun Kim. "Thermohydrodynamic Analysis of Surface Roughness in the Flow Field". Journal of Tribology 127, n. 2 (1 aprile 2005): 293–301. http://dx.doi.org/10.1115/1.1828072.

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The study deals with the development of a thermohydrodynamic (THD) computational procedure for evaluating the pressure, temperature, and velocity distributions in fluid films with a very rough geometry. A parametric investigation is performed to predict the bearing behaviors in the lubricating film with the absorbed layers and their interfaces as determined by rough surfaces with Gaussian distribution. The layers are expressed as functions of the standard deviations of each surface to characterize flow patterns between both rough surfaces. Velocity variations and heat generation are assumed to occur in the central (shear) zone with the same bearing length and width. The coupled effect of the surface roughness and shear zone dependency on the hydrodynamic pressure and temperature has been found in the noncontact mode. The procedure confirms the numerically determined relationship between the pressure and film gap, provided that its roughness magnitude is smaller than the fluid film thickness.

Li, Chang He, Zhen Lu Han e Jing Yao Li. "Investigation into Fluid Velocity Field of Wedge-Shaped Gap in Grinding". Applied Mechanics and Materials 37-38 (novembre 2010): 593–98. http://dx.doi.org/10.4028/www.scientific.net/amm.37-38.593.

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In the grinding process, grinding fluid is delivered for the purposes of chip flushing, cooling, lubrication and chemical protection of work surface. Hence, the conventional method of flood delivering coolant fluid by a nozzle in order to achieve high process performance purposivelly. However, hydrodynamic fluid pressure can be generated ahead of the grinding zone due to the wedge effect between wheel peripheral surface and part surface. In this paper, a theoretical fluid velocity field modeling is presented for flow of coolant fluid of wedge-shaped gap in flood delivery surface grinding, which is based on navier-stokes equation and continuous formulae. The numerical simulation results showed that the velocity in the x direction was dominant and the side-leakage in the y direction existed. The velocity in the z direction was smaller than the others because of the assumption of laminar flow. The smaller the gap is, the larger the velocity in the x direction. The magnitude of the velocity is also proportional to the surface velocity of the wheel.

BAL, GUILLAUME, e KUI REN. "RECONSTRUCTION OF SINGULAR SURFACES BY SHAPE SENSITIVITY ANALYSIS AND LEVEL SET METHOD". Mathematical Models and Methods in Applied Sciences 16, n. 08 (agosto 2006): 1347–73. http://dx.doi.org/10.1142/s021820250600156x.

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We consider the reconstruction of singular surfaces from the over-determined boundary conditions of an elliptic problem. The problem arises in optical and impedance tomography, where void-like structure or cracks may be modeled as diffusion processes supported on co-dimension one surfaces. The reconstruction of such surfaces is obtained theoretically and numerically by combining a shape sensitivity analysis with a level set method. The shape sensitivity analysis is used to define a velocity field, which allows us to update the surface while decreasing a given cost function, which quantifies the error between the prediction of the forward model and the measured data. The velocity field depends on the geometry of the surface and the tangential diffusion process supported on it. The latter process is assumed to be known in this paper. The level set method is next applied to evolve the surface in the direction of the velocity field. Numerical simulations show how the surface may be reconstructed from noisy estimates of the full, or local, Neumann-to-Dirichlet map.

Hosokawa, Y., e K. Furukawa. "Surface Flow and Particle Settling in a Coastal Reed Field". Water Science and Technology 29, n. 4 (1 febbraio 1994): 45–53. http://dx.doi.org/10.2166/wst.1994.0154.

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Hydraulic roughness of reed stems in shallow surface flow under low current velocity is discussed. The roughness coefficient, defined as a Manning's formula, depends upon depth and velocity in this flow. Depth and velocity, in turn, are altered by roughness through water surface slope. The interaction between these three parameters must be solved simultaneously for the prediction of the surface flow in a reed wetland. Stem roughness can be expressed as a function of Reynolds' number, similar to that for a single cylinder. Assigning this function, an iteration method easily gives us a suitable set of three parameters. Settling experiments show that stems promote vertical mixing of fine particles in shallow flow. The model of vertically uniform SS concentration is more suitable. Though the observed data fluctuated widely, the apparent settling velocity of fine particles in the flow was very close to the settling velocity in quiescent water. Using the above two models, one for flow and the other for settling in shallow wetland, we can estimate the clarification potential of a reed field under given hydraulic conditions and particle load. Numerical experiments show that fine particles tend to accumulate on the bottom of a reed field, as often observed in natural wetlands.

Yan, He, Qianru Hou, Guodong Jin, Xing Xu, Gong Zhang e Daiyin Zhu. "Velocity Estimation of Ocean Surface Currents in along-Track InSAR System Based on Conditional Generative Adversarial Networks". Remote Sensing 13, n. 20 (13 ottobre 2021): 4088. http://dx.doi.org/10.3390/rs13204088.

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Velocity estimation of ocean surface currents is of great significance in the fields of the fishery, shipping, sewage discharge, and military affairs. Over the last decade, along-track interferometric synthetic aperture radar (along-track InSAR) has been demonstrated to be one of the important instruments for large-area and high-resolution ocean surface current velocity estimation. The calculation method of the traditional ocean surface current velocity, as influenced by the large-scale wave orbital velocity and the Bragg wave phase velocity, cannot easily separate the current velocity, characterized by large error and low efficiency. In this paper, a novel velocity estimation method of ocean surface currents is proposed based on Conditional Generative Adversarial Networks (CGANs). The main processing steps are as follows: firstly, the known ocean surface current field diagrams and their corresponding interferometric phase diagrams are constructed as the training dataset; secondly, the estimation model of the ocean surface current field is constructed based on the pix2pix algorithm and trained by the training dataset; finally, the interferometric phase diagrams in the test dataset are input into the trained model. In the simulation experiment, processing results of the proposed method are compared with those of traditional ocean surface current velocity estimation methods, which demonstrate the efficiency and effectiveness of the novel method.

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Tesi sul tema "Surface velocity field":

Ahmed, Zahir Uddin. "An experimental and numerical study of surface interactions in turbulent swirling jets". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2016. https://ro.ecu.edu.au/theses/1790.

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Convective heat transfer and drying processes are found in industrial applications from gas turbine blade cooling to drying of food products and paper. In many instances, these processes rely on either a single or an array of fluid jets which impinge onto a surface. Traditionally, non-swirling impinging jets have been used, but interest surrounds possible advantages from imposing swirl into these jets to further promote heat and mass transfer at the surface. The challenge of resolving this question is that including swirl further complicates fluid-surface interactions. Studies are faced with the complexity of flow behaviour, the need for intricate measurement techniques and jets which seamlessly transition from non-swirling to swirling with well-defined boundary conditions. To better understand the nature of turbulent jet impingement with, and without, swirl requires carefully designed experiments covering parameters believed to affect the magnitude and uniformity of heat transfer. This research investigated, experimentally and numerically, incompressible turbulent impinging air jets using aerodynamically derived swirl. The aim was to elucidate the effects of different parameters on fluid flow and surface heat transfer characteristics. Measurements of mean velocity and turbulence, surface pressure and temperatures were done using Constant Temperature Anemometry, integrating micro-manometer (pressure) tappings and steady-state heated thin foil technique via infrared thermography. Imaging for flow visualisations was also done. Numerical simulations were performed using ANSYS Fluent (version 14.5). Test conditions investigated encompassed a range of Reynolds numbers (Re = 11,600 – 35,000), swirl numbers (S = 0 – 1.05) and nozzle-to-plate distances (H = 1D – 6D). Results show that the use of low-to-medium swirl numbers (S = 0.27 – 0.45) is found to improve heat transfer (Nu) in the impingement region compared to non-swirling (S = 0) jets over H ≤ 4D, with little improvement in spatial Nu uniformity. When S further increases, significant enhancement in Nu occurs only at near-field impingement (H ≤ 2D), regardless of the impingement area (footprint). At H ≥ 4D, a significantly low but more uniform radial profile of Nu is obtained. Results conclude the effect of swirl on the heat transfer characteristics is a complex relationship, which depends on the Reynolds number and nozzleto- plate distance. Whilst high swirl can lead to significant improvements in heat transfer, this is not necessarily always the case. It appears that there exist a threshold impingement distance and a transitional swirl number (dependent on Re) over which the effect of swirl on field and turbulence at different swirl numbers and nozzle-to-plate distances, with flow recirculation in near-field impingement (H = 2D) and non-swirl like at far-field (H = 6D). The occurrence of peak heat transfers at different swirl numbers is largely correlated with swirl induced turbulence characteristics near the impingement surface. Increase in Reynolds number augments the magnitude of Cp and heat transfer. For a given S, flow field and heat transfer distributions are found to be largely independent of Re.

Baaklini, Georges. "Characterization of the Eastern Mediterranean surface dynamics : Insights from drifter assimilation and machine learning techniques". Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS186.

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Une estimation précise de la circulation de surface est cruciale en raison de son impact direct sur les propriétés physiques et bio-géochimiques du du milieu marin. Cependant, l’estimation des courants reste un défi car le champ de circulation est affecté par des flux qui changent rapidement. Ce problème s’accentue en Méditerranée orientale, où les observations in-situ sont relativement rares et où les imprécisions des observations altimétriques augmentent. Par conséquent, certaines des caractéristiques de méso-échelle sont encore débattues ou inconnues, en particulier dans le bassin levantin. L’objectif de la thèse est de caractériser ces structures méso-échelles hautement évolutives dans la mer Méditerranée. Dans la première partie de la thèse, nous présentons une méthode d’assimilation variationnelle qui fusionne l’altimétrie satellitaire avec les observations des bouées pour améliorer la représentation de la circulation de surface le long et autour des trajectoires des bouées assimilées. Nous évaluons l’efficacité de la méthode en comparant les vitesses résultant de l’assimilation avec des observations in-situ indépendantes et des images couleur de l’océan. Nous utilisons ensuite les vitesses corrigées pour caractériser les événements locaux et à court terme qui se produisent dans le bassin du Levant. Cependant, en raison des lacunes spatio-temporelles importantes dans la couverture des bouées, l’assimilation ne permet pas une investigation continue de toutes les structures mésoéchelles et de leurs variabilités à long terme dans le bassin. Dans la deuxième partie de la thèse, nous présentons des techniques de “machine learning” qui seront utilisées pour construire un catalogue des différents régimes de circulation dans le bassin levantin, permettant ainsi la caractérisation à long terme de ces structures. Nous essayons également d’expliquer les raisons possibles derrière les évaluations contradictoires précédentes de certaines structures, comme par exemple, le “Mid-Mediterranean Jet”. Les résultats obtenus dans cette thèse améliorent la connaissance des caractéristiques,des comportements et des tendances des principales structures méso-échelle. Les applications de la thèse pourraient tirer profit d’autres observations in-situ et de futures missions altimétriques comme SWOT, promettant ainsi de pallier certaines des lacunes actuelles de l’altimétrie
An accurate estimation of the surface circulation is crucial because of its direct impact on physical and bio-geochemical water properties. However, currents estimation remains challenging because the stream field is affected by quickly changing flows. This problem increases in the Eastern Mediterranean Sea, where in-situ observations are relatively scarce and the inaccuracies of altimetric observations increase. Therefore, some of the mesoscale features are still debated or unknown, especially in the Levantine Basin. The thesis goal is to characterize these highly-evolving mesoscale features. In the first part of the thesis, we present a variational assimilation method that merges altimetry with drifters to improve the surface circulation representation along and around the assimilated drifters’ trajectories. We assess the method’s efficiency by comparing the velocities resulting from assimilation with independent in-situ observations and ocean color images. We use the corrected velocities to characterize short-term and local events occurring in the Levantine Basin. However, because of the significant spatio-temporal gaps in drifters’ coverage, the assimilation does not allow a continuous investigation of all the mesoscale patterns and their long-term variabilities in the basin. In the second part of the thesis, we use machine learning techniques to build a catalog of the several circulation regimes in the Levantine Basin, providing a long-term characterization of these features. We also try to explain the possible reasons behind previous contradictory assessments about some features, such as the Mid-Mediterranean Jet. The obtained results in the thesis improve the knowledge of the main mesoscale features’ characteristics, behaviors, and tendencies. The thesis applications could take advantage of other in-situ observations and of future altimetric missions like SWOT, promising to mitigate some of the actual altimetric shortcomings

Harding, Samuel Frederick. "Unsteady velocities of energetic tidal currents : an investigation into dynamic flow effects on lifting surfaces at field and experimental scale". Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8037.

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The generation of electricity from tidal currents is an emerging industry with the potential to contribute to the UK energy supply in a predictable and sustainable way. The development of the technology requires the cost effective subsea installation of energy conversion systems in an energetic and challenging marine environment. One concept developed for the fastening of tidal energy converters to the seabed is the Active Gravity Base (AGB), which offers potential reductions in installation cost and time, relative to existing fastening methods. The performance of this concept in response to unsteady flow conditions is explored within this thesis. The dynamic behaviour of a tidal current is driven by a range of factors from gravitational forces of celestial bodies to high-frequency fluctuations of turbulent eddies. The response of the AGB concept to the unsteadiness of tidal currents is herein considered under the two broad time-scales; the directionality of the mean semi-diurnal cycle and the high frequency variations from a given mean flow velocity. The correlation between the direction and velocity of the tidal flow was assessed using hourly averaged data provided by the Admiralty Charts in the northern UK waters. The resulting directionality model was used to predict the performance of the AGB under a range of quasi-steady flow conditions. High frequency velocity measurements of a potential tidal energy site were obtained through collaboration with the University of Washington and the Pacific Northwest National Laboratory. This data was used to estimate the maximum perturbation from the mean velocity that can be expected on an annual basis. An experimental facility was developed within the re-circulating water flume at the University of Edinburgh to examine the dynamic loads generated by controllable two-dimensional flow perturbations. This was successfully achieved using a configuration of twin pitching foils with independent motion control. A relationship between the foil pitch angle and velocity perturbation time series was predicted using a vortex model of the foil wakes. This configuration was shown to be able to generate significant flow fluctuations within the range of reduced frequencies 0:06 ≤ k ≤ 1:9, with a peak gust intensity of Ig = 0:5. The numerical solution was validated against experimental results.

Taggart, Douglas Michael. "Determination of near-surface velocity fields in the CTZ using combined altimetric and inverse modelling techniques". Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/26981.

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Approved for public release; distribution is unlimited
An inverse model involving AVHRR imagery and the heat equation with dynamical constraints on the divergence, kinetic energy and vorticity of the solutions was used by Kelly (1989) to produce velocity fields that were in good agreement with Acoustic Doppler Current Profiles (ADCP) data. Dynamic heights derived from GEOSAT radar altimeter data have also been used to determine near-surface geostrophic currents. Synthetic GEOSAT-derived velocity data was generated ADCP data collected as part of the Coastal Transition Zone (CTZ) Field Program. The inverse model was run with AVHRR imagery that was coincident to the CTZ Field Program ACDP data and the synthetic velocity data was added as an additional constraint on the model's solution. The resulting velocity solutions were much improved over those given by the inverse model alone. Refinement of this method involving a combination of different data sources should improve efforts to determine near-surface velocities of the ocean entirely by remote means.

de, Naray Rachel Kuzio. "High resolution optical velocity fields of low surface brightness galaxies and the density profiles of dark matter halos". College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7239.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Astronomy. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Lemon, Michael R. "Comparison of Los Alamos National Laboratory (LANL) Parallel Ocean Program (POP) model velocity fields with Pacific surface drifter measurements". Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA341312.

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Thesis (M.S. in Physical Oceanography) Naval Postgraduate School, September 1997.
"September 1997." Thesis advisor(s): Julie L. McClean, Jeffrey D. Paduan. Includes bibliographical references (p. 111-114). Also available online.

Su, Yuan-Te, e 蘇芫德. "Horizontal two-dimensional bed-load grain and water surface velocity fields in dam breach experiment". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/49359604400294478518.

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碩士
國立臺灣大學
土木工程學研究所
103
Dam breaching consists of water flow and sediment transport. The connections between water and bed-load velocity and dam breach topography changes in downstream are the purpose in this study. Previous researches are devoted to observe dam breach phenomenon from side view. From top view, the flow field changed by terrain and the surface flow can be observed. A simplified laboratory experiment is conducted to obtain horizontal two dimensional velocity fields. In order to compare water surface and bed-load velocity, we use two different color and density particles to record water and bed-load motion synchronized. The particle tracking velocimetry (PTV) method is used to analyze velocity fields. The topography is acquired as Digital Elevation Model (DEM) using the software Photoscan, Agisoft. According to the DEM, the changing of topography can be discussed. The flow field can be projected to topography as 3 dimensional flow field. Using this approach, we successfully obtain both water surface velocities and bed-load velocities. We found that water surface velocity will affect the bed-load velocity. Besides, the topography have similar pattern to real dam breach events. Finally, the mass conservation can be used to estimate topography changing rate of bed-load if particles velocities are given.

Libri sul tema "Surface velocity field":

Taggart, Douglas Michael. Determination of near-surface velocity fields in the CTZ using combined altimetric and inverse modelling techniques. Monterey, Calif: Naval Postgraduate School, 1991.

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Gampert, B. The Influence of Polymer Additives on Velocity and Temperature Fields: Symposium Universität -- GH -- Essen, Germany, June 26-28, 1984. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986.

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Lemon, Michael R. Comparison of Los Alamos National Laboratory (LANL) Parallel Ocean Program (POP) model velocity fields with Pacific surface drifter measurements. Monterey, Calif: Naval Postgraduate School, 1997.

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Capitoli di libri sul tema "Surface velocity field":

Wang, Yong, Chen Xu, Changchun Li, Xiaofei Yao, Xingbo Xiang e Haoxuan Huang. "Surface Vibration of Throw-Type Blast in an Open-Pit Mine". In Lecture Notes in Civil Engineering, 123–36. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2532-2_11.

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AbstractIn the process of Open-pit mining in China, throwing blasting is an important method, which is very likely to cause serious damage to the slope of the discharge field under the action of vibration load of throwing blasting. With the background of throwing blasting process in Heidaigou open-pit mine in Ordos, vibration velocity data were collected from the discharge field near the throwing blast, and the vibration signal of throwing blast was analyzed by means of Fourier transform to obtain the characteristics of throwing blast vibration velocity wave and the attenuation law and prediction formula in the process of propagation. The results show that: 100 ~ 300 m away from the blasting area, the radial direction (X direction) of the blasting area produces the largest vibration velocity of 26.8 cm/s, but at the same time, the decay rate of the peak vibration velocity of the survey line 2 in each direction is small, and the decay percentages of 56, 75 and 70% are smaller than that of the survey line 1 and survey line 3 in the lateral direction of the blasting area, and the decay rate of the velocity is smaller as the propagation As the distance increases, the decay rate of the velocity decreases. The curve gradually tends to flatten and the vibration velocity of the three directions gradually close. The frequency band of the blast vibration is distributed within 200 Hz and the frequency and energy are mainly distributed in the low frequency stage (0–20 Hz), accounting for more than 50% of the total energy.

Erben, Andreas, Alexander Geist, Immanuel Voigt, Björn Senf, Thomas Mäder, Janine Glänzel, Steffen Ihlenfeldt e Welf-Guntram Drossel. "Smart Pressure Film Sensor for Machine Tool Optimization and Characterization of the Dynamic Pressure Field on Machine Surfaces". In Lecture Notes in Production Engineering, 179–91. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-34486-2_14.

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AbstractKnowledge of thermal interactions with the environment is essential for improving the performance of machine tools. Therefore, it is necessary to detect and quantify the convective heat flows at machine tool surfaces, that occur in the workspace as a result of cutting fluid use or outside the machine due to active air flow. Thin-film sensors made of shape memory alloys with integrated small temperature sensors are suitable for detecting very fine pressure differences and can be used to estimate convective heat transfer. By measuring the pressure differences, the dynamic pressure field at the surface can be determined. Since the pressure field correlates with the flow field, conclusions can be drawn about the flow velocity. This leads to more profound and extended possibilities to match flow fields from CFD simulations with measured data. At the same time, the surface temperature is also recorded by this sensor. Reference measurements of the temperature in the free flow are used to characterize the heat transfer. By knowing the pressures, temperatures and the correlating flow velocity near the wall, the heat transfer coefficient can be determined. Against this background, this paper demonstrates the behavior of shape memory alloys as fluid pressure sensors and addresses the development of such sensors for machine tools. For this purpose, sensor units are to be developed that can be placed as a sensor network (composite of several sensors on one surface) inside and outside the workspace.

Yefimov, V. V., e B. A. Nelepo. "Aspects of the Velocity Field And Dispersion Relation In Surface Wind Waves". In Wave Dynamics and Radio Probing of the Ocean Surface, 193–206. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-8980-4_13.

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Howard, Robert F. "Observations of Surface Velocity Fields". In The Internal Solar Angular Velocity, 23–26. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3903-5_4.

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Jing, Ye, Xueting Lei, Jie Qin, Teng Wu e Elikplim Agbemafle. "On Characterizing Flow Resistance in a Tidal Reach". In Lecture Notes in Civil Engineering, 1512–21. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6138-0_134.

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AbstractThe tidal reaches are characterized by unsteady and non-uniform flow (UNF), which is significantly different from the commonly assumed steady and uniform flow (SUF) in hydraulics. The SUF shows invariant temporal and spatial flow characteristics, and thus flow acceleration is absent in a prismatic channel. However, for the UNF, the variation of flow velocity and depth in both temporal and spatial scales causes the loss of flow energy, and thus increases the flow resistance. In order to clarify the variation of flow resistance and its influencing factors in tidal reaches, this study investigates the flow resistance characteristics under UNF conditions. In this study, a typical tidal section of the Lower Yangtze River (LYR) – Kouanzhi Waterway (KW) – was selected as the study area, where the temporal variation of water surface along the river course at different tide levels, the bathymetry of multiple cross-sections, the distribution of cross-sectional flow velocity and its temporal variation were measured in detail. Based on these field measurement data, the contribution terms to the energy slope were calculated and evaluated, by decomposing the momentum equation. The calculated contributing terms include water surface gradient, local acceleration, and convective acceleration. The results showed that the local acceleration and convective acceleration have a substantial impact on the energy slope during specific time periods, which was found to be more significant than the findings in previous studies. The results show that the local acceleration term is more significant than the convective acceleration term except when the water surface slope is close to zero, and its contribution is significant throughout the flood tide and the initial ebb tide periods. The above research results are of great significance for the investigation of flow resistance mechanisms and numerical simulations in tidal rivers.

Imawaki, Shiro, Hiroshi Uchida, Kaoru Ichikawa e Daisuke Ambe. "Estimating the High-Resolution Mean Sea-Surface Velocity Field by Combined use of Altimeter and Drifter Data for Geoid Model Improvement". In Space Sciences Series of ISSI, 195–204. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-1333-7_16.

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Torres-Bárcenas, Aram, Roberto Alejandro Vargas-Domínguez, Carlos Arturo Debernardi-Aguirre, Francisco Javier Solorio-Ordaz e Rafael Chávez Martínez. "Effect of the Sierpinski Carpet on the Convective Flow on a Squared Fin Under Natural Convection". In Proceedings of the XV Ibero-American Congress of Mechanical Engineering, 217–23. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-38563-6_32.

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AbstractThe present experimental work is aimed to study the convective flow generated on the surface of four squared copper fins of 10 cm per side and 0.314 cm thickness. Three of them were manufactured according to the first three iterations of the Sierpinski carpet fractal. The experiments were carried out for different input power at the base of the fins, 4.7 W, 9.0 W, and 13.7 W. Particle image velocimetry was used to measure the velocity fields and the Schlieren technique to visualize the thermal boundary layer. Results showed that higher the input power, higher the velocity of the hydrodynamic boundary layer. In addition, the thermal and the hydrodynamic boundary layers increased in thickness. On the other hand, the heat exchange area diminishes for the higher iterations of the fractal, resulting in lower velocities of the hydrodynamic boundary layer and smaller temperature gradients on the thermal boundary layer. Furthermore, the manufactured perforations disturb the convective flow.

Resseguier, Valentin, Erwan Hascoët e Bertrand Chapron. "Random Ocean Swell-Rays: A Stochastic Framework". In Mathematics of Planet Earth, 259–71. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-18988-3_16.

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AbstractOriginating from distant storms, swell systems radiate across all ocean basins. Far from their sources, emerging surface waves have low steepness characteristics, with very slow amplitude variations. Swell propagation then closely follows principles of geometrical optics, i.e. the eikonal approximation to the wave equation, with a constant wave period along geodesics, when following a wave packet at its group velocity. The phase averaged evolution of quasi-linear wave fields is then dominated by interactions with underlying current and/or topography changes. Comparable to the propagation of light in a slowly varying medium, over many wavelengths, cumulative effects can lead to refraction, i.e. change of the direction of propagation of a given wave packet, so that it departs from its initial ray-propagation direction. This opens the possibility of using surface swell systems as probes to estimate turbulence along their propagating path.

Lauga, Eric. "2. Viscosity". In Fluid Mechanics: A Very Short Introduction, 18–31. Oxford University Press, 2022. http://dx.doi.org/10.1093/actrade/9780198831006.003.0002.

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‘Viscosity’ begins by examining how fluid motion is quantified using the flow velocity. Since fluids can move in three independent directions of space, the velocity is a three-dimensional vector, with each component measuring the velocity in a particular direction. Because the velocity can take different values at different locations in space, it is called a field. Flow kinematics is about the various ways in which fluids can move. There are three fundamental flow modes: translation, rotation, and extension. Extension is the only flow component that is the true deformation. Invoking the concept of conservation of mass, we have the issue of incompressibility of the flow. The forces arising inside a fluid are at the heart of fluid dynamics. There is a difference between volume forces (e.g. gravity) and surface forces. An important surface force acting tangentially along surfaces is called a shear stress. Using Isaac Newton’s famous shear-flow experimental setup, where a fluid is located between two rigid surfaces that slide past each other. The shear stress acting on a surface is proportional to the shear rate in the fluid and to a material property called the viscosity. Fluids with a high viscosity experience larger shear stresses.

Liu, Tingsen, Mian Yan, Xiangbo Song e Yongtai He. "Geometry Optimization of Hot Water Storage Tank Based on Numerical Simulation". In Advances in Energy Research and Development. IOS Press, 2022. http://dx.doi.org/10.3233/aerd220018.

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Using ANSYS software, the heat transfer process of hot water storage tank in spherical, cylindrical and square shapes was numerically simulated, and the distribution of the external wind velocity field and the temperature field under the same working conditions was studied. According to the change of average hot water temperature with time, it is concluded that spherical hot water storage tank can help reduce heat loss. Based on velocity field and temperature field distribution, it is found that the heat loss of the spherical hot water storage tank mainly occurs on the annular surface perpendicular to the windward side. By thickening the thermal insulation layer, it is possible to reduce the heat loss on the surface of the spherical water storage tank and improve the thermal insulation effect.

Atti di convegni sul tema "Surface velocity field":

Douma, Huub, e Matthew Haney. "Surface‐wave inversion for near‐surface shear‐wave velocity estimation at Coronation field". In SEG Technical Program Expanded Abstracts 2011. Society of Exploration Geophysicists, 2011. http://dx.doi.org/10.1190/1.3627466.

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Oliveira, Luiz, e Pablo Andrés Muñoz Rojas. "2D Shape Optimization Based on a NURBS Surface Velocity Field". In 7th International Symposium on Solid Mechanics. ABCM, 2019. http://dx.doi.org/10.26678/abcm.mecsol2019.msl19-0146.

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Zuhui Chen, Xing Zhou, Guojun Zhu e Shihuan Lin. "Surface recombination/generation velocity in metal-oxide-silicon field-effect transistors". In 2009 IEEE International Conference of Electron Devices and Solid-State Circuits (EDSSC 2009). IEEE, 2009. http://dx.doi.org/10.1109/edssc.2009.5394175.

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Chen, Wei. "The global optimal surface velocity field near shoreline from infrared images". In International Symposium on Photoelectronic Detection and Imaging 2009, a cura di Jeffery Puschell, Hai-mei Gong, Yi Cai, Jin Lu e Jin-dong Fei. SPIE, 2009. http://dx.doi.org/10.1117/12.835869.

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Boiero, D., R. Wisén, M. Maraschini e L. V. Socco. "Shear Wave Velocity Model from Surface Wave Analysis – A Field Case Example". In 72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010. European Association of Geoscientists & Engineers, 2010. http://dx.doi.org/10.3997/2214-4609.201401024.

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Greenhalgh, S. A., X. Liu e B. Zhou. "Velocity and Attenuation Dispersion Relations for the Effective Biot Double Porosity Model: Total Field Formulation". In Near Surface 2010 - 16th EAGE European Meeting of Environmental and Engineering Geophysics. European Association of Geoscientists & Engineers, 2010. http://dx.doi.org/10.3997/2214-4609.20144902.

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Farokhi, S., A. Nekahi e M. Farzaneh. "Velocity and electric field of the arc root propagating over an ice surface". In 2013 IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP 2013). IEEE, 2013. http://dx.doi.org/10.1109/ceidp.2013.6748196.

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Goto, Shintaro, Kumi Nakai, Naoki Kanda, Yuto Iwasaki, Taku Nonomura e Keisuke Asai. "Data-driven Reconstruction of Velocity Field around Airfoil using Unsteady Surface Pressure Measurement". In AIAA SCITECH 2022 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2022. http://dx.doi.org/10.2514/6.2022-0139.

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Ponomarenko, A. V., B. M. Kashtan, V. N. Troyan e W. A. Mulder. "Estimating a Continuous P-wave Velocity Profile with Constant Squared-slowness Gradient Models from Seismic Field Data". In Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics. Netherlands: EAGE Publications BV, 2015. http://dx.doi.org/10.3997/2214-4609.201413796.

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Ramstorfer, Franz, Bernd Breitscha¨del, Helfried Steiner e Gu¨nter Brenn. "Modelling of the Near-Wall Liquid Velocity Field in Subcooled Boiling Flow". In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72182.

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The subject of the present work is the modelling of the liquid streamwise flow velocity in the two-phase boundary layer in subcooled boiling flow under the influence of the vapor bubbles. Subcooled boiling flow experiments were carried out in a horizontal test channel in order to investigate the interaction between the bubbles and the liquid phase. The heater surface was located at the bottom of the test channel. The near-wall liquid flow velocity was measured using a two-component laser-Doppler anemometer. Based on the experimental data a model is proposed to describe the impact of the gaseous phase on the motion of the liquid in the subcooled boiling regime. It was observed that the axial velocity profiles near the wall follow a logarithmic law similar to that used in turbulent single-phase flow over rough surfaces. Based on this finding it is suggested to model the influence of the bubbles on the liquid flow analogously to the effect of a surface roughness. The correlation developed for an equivalent surface roughness associated with the bubbles yields good agreement of the modeled axial velocity profiles with the experimental data.

Rapporti di organizzazioni sul tema "Surface velocity field":

Ray, Laura, Madeleine Jordan, Steven Arcone, Lynn Kaluzienski, Benjamin Walker, Peter Ortquist Koons, James Lever e Gordon Hamilton. Velocity field in the McMurdo shear zone from annual ground penetrating radar imaging and crevasse matching. Engineer Research and Development Center (U.S.), dicembre 2021. http://dx.doi.org/10.21079/11681/42623.

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The McMurdo shear zone (MSZ) is strip of heavily crevassed ice oriented in the south-north direction and moving northward. Previous airborne surveys revealed a chaotic crevasse structure superimposed on a set of expected crevasse orientations at 45 degrees to the south-north flow (due to shear stress mechanisms). The dynamics that produced this chaotic structure are poorly understood. Our purpose is to present our field methodology and provide field data that will enable validation of models of the MSZ evolution, and here, we present a method for deriving a local velocity field from ground penetrating radar (GPR) data towards that end. Maps of near-surface crevasses were derived from two annual GPR surveys of a 28 km² region of the MSZ using Eulerian sampling. Our robot-towed and GPS navigated GPR enabled a dense survey grid, with transects of the shear zone at 50 m spacing. Each survey comprised multiple crossings of long (> 1 km) crevasses that appear in echelon on the western and eastern boundaries of the shear zone, as well as two or more crossings of shorter crevasses in the more chaotic zone between the western and eastern boundaries. From these maps, we derived a local velocity field based on the year-to-year movement of the same crevasses. Our velocity field varies significantly from fields previously established using remote sensing and provides more detail than one concurrently derived from a 29-station GPS network. Rather than a simple velocity gradient expected for crevasses oriented approximately 45 degrees to flow direction, we find constant velocity contours oriented diagonally across the shear zone with a wavy fine structure. Although our survey is based on near-surface crevasses, similar crevassing found in marine ice at 160 m depth leads us to conclude that this surface velocity field may hold through the body of meteoric and marine ice. Our success with robot-towed GPR with GPS navigation suggests we may greatly increase our survey areas.

Ziegler, Nancy, Nicholas Webb, Adrian Chappell e Sandra LeGrand. Scale invariance of albedo-based wind friction velocity. Engineer Research and Development Center (U.S.), maggio 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.

Baumgardner, Davis e Olsen. PR-179-13205-R01 Field Evaluation of Oxidation Catalyst Degradation - 2-Stroke Lean-Burn NG Engine. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), ottobre 2015. http://dx.doi.org/10.55274/r0010036.

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This study examines the degradation of an exhaust oxidation catalyst on a Cooper-Bessemer GMVH 12C2 gas engine. Critical parameters were determined, such as light-off temperature and reduction efficiency at 450 and 600?F. The catalyst surface was analyzed to examine the location and rate of poison deposition. Catalyst life was examined based on NESHAP guidelines. Catalyst life is strongly dependent on catalyst temperature and space velocity. For similar industrial applications, if the engine unit particulars are known, site operators can use the information in this study to predict when the oxidation catalyst will need to be either replaced or regenerated (washed).

Welp, Timothy, Brian Harris, Brian McFall, Zachary Tyler, Colton Beardsley, Adrienne Eckstein, David Perkey et al. Development and testing of the Sediment Distribution Pipe (SDP) : a pragmatic tool for wetland nourishment. Engineer Research and Development Center (U.S.), aprile 2024. http://dx.doi.org/10.21079/11681/48411.

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Standard dredging operations during thin layer placement (TLP) projects are labor intensive as crews are necessary to periodically move the outfall location, which can have lasting adverse effects on the marsh surface. In an effort to increase efficiency during TLP, a novel Sediment Distribution Pipe (SDP) system was investigated. This system offers multiple discharge points along the pipeline to increase the sediment distribution while reducing pipeline movements. An SDP Modeling Application (SDPMA) was developed to assist in the design of SDP field applications by quickly assessing the pressure and velocity inside the discharge pipe and approximating the slurry throw distances. An SDP field proof of concept was performed during a two-phase TLP on Sturgeon Island, New Jersey, in 2020. The SDPMA was shown to be an accurate method of predicting performance of the SDP. The SDP was successful at distributing dredge material across the placement site; however, further research is warranted to better quantify performance metrics.

Bell, Gary, David Abraham, Nathan Clifton e Lamkin Kenneth. Wabash and Ohio River confluence hydraulic and sediment transport model investigation : a report for US Army Corps of Engineers, Louisville District. Engineer Research and Development Center (U.S.), marzo 2022. http://dx.doi.org/10.21079/11681/43441.

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Avulsions of the Wabash River in 2008 through 2011 at its confluence with the Ohio River resulted in significant shoaling in the Ohio River. This caused a re-alignment of the navigation channel and the need for frequent dredging. A two-dimensional numerical hydrodynamic model, Adaptive Hydraulics (AdH), was developed to simulate base (existing) conditions and then altered to simulate multiple alternative scenarios to address these sediment issues. The study was conducted in two phases, Phase 1 in 2013 – 2015 and Phase 2 in 2018 – 2020. Field data were collected and consisted of multi-beam bathymetric elevations, bed sediment samples, suspended sediment samples, and discharge and velocity measurements. The model hydrodynamic and sediment transport computations adequately replicated the water surface slope, flow splits, bed sediment gradations, and suspended sediment concentrations when compared with field data. Thus, it was shown to be dependable as a predictive tool. The alternative that produced the most desirable results included a combination of three level-crested emergent dikes on Wabash Island and four submerged dikes on the Illinois shore with a level crest from the bank to the tip of the dike. The selected alternative produced an improved sailing line while maintaining authorized channel depths.

McKnight, C., David May e 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.), novembre 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.

Bruce. L51642 Field Nondestructive Examination of ERW Pipe Seams. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), giugno 1991. http://dx.doi.org/10.55274/r0010587.

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Electric resistance welded (ERW) pipe has been used in the natural gas transmission industry for many years. The Department of Transportation (DOT) has recently expressed interest in the integrity of the weld seam in pipelines made from ERW pipe that was manufactured prior to 1970. Specifically, the DOT has requested that natural gas transmission and hazardous liquid pipeline operators determine whether or not their pipelines that meet this description require hydrostatic proof testing. The initial concern from the DOT was for seam weld selective corrosion, although reference has since been made to growth of manufacturing discontinuities in the ERW seam. Early ERW pipe was manufactured using either direct current or low-frequency alternating current, processes that were prone to producing incomplete fusion discontinuities. These discontinuities (also referred to as cold welds, penetrators, etc.), if present in a pipeline, can grow under normal service or under upset operating conditions resulting in leaks or ruptures. There exists a need for a method that a pipeline operator could use to demonstrate the integrity of pipelines that were made from this older ERW pipe other than hydrostatic testing, which is expensive and potentially harmful to pipeline integrity. The use of a nondestructive-examination (NDE) technique would enable an operator to sample the integrity of a suspect pipeline during other routine in-service maintenance operations without the need for hydrostatic testing. The detection of incomplete fusion discontinuities is difficult if not impossible with conventional NDE techniques. The intimate mechanical contact between compressed surfaces causes a small amount of reflection and a large amount of transmission of ultrasonic signals. Recently however, several ultrasonic techniques have been introduced to study these types of discontinuities in resistance spot welds and inertia friction welds. These new techniques are based on ultrasonic spectroscopy, that is, the frequency dependence of the various ultrasonic interfacial parameters. These parameters include reflection and transmission coefficients and the frequency dependence of ultrasonic volumetric parameters (e.g., velocity and attenuation).