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Bibliografias temáticas / Drift current

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Literatura científica selecionada sobre o tema "Drift current"

Autor: Grafiati

Publicado: 9 de novembro de 2024

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Artigos de revistas sobre o assunto "Drift current"

1

Nakayama, Yoshihiro, Kay I. Ohshima e Yasushi Fukamachi. "Enhancement of Sea Ice Drift due to the Dynamical Interaction between Sea Ice and a Coastal Ocean". Journal of Physical Oceanography 42, n.º 1 (1 de janeiro de 2012): 179–92. http://dx.doi.org/10.1175/jpo-d-11-018.1.

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Abstract Wind factor, the ratio of sea ice drift speed to surface wind speed, is a key factor for the dynamics of sea ice and is generally about 2%. In some coastal oceans, however, the wind factor tends to be larger near the coast. This study proposes the enhancement mechanism of the sea ice drift caused by the dynamical coupling between sea ice and a coastal ocean. In a coastal ocean covered with sea ice, wind-forced sea ice drift excites coastal trapped waves (shelf waves) and generates fluctuating ocean current. This ocean current can enhance sea ice drift when the current direction is the same as that of the wind-driven drift. The authors consider a simplified setting where spatially uniform oscillating wind drifts sea ice parallel to the coast. When a barotropic long shelf wave is assumed for the ocean response, sea ice drifts driven by wind and ocean are obtained analytically. The ratio of ocean-driven to wind-driven sea ice drifts is used for the evaluation of the oceanic contribution to the enhancement of sea ice drift. The enhancement is mostly determined by the characteristics of the shelf waves, and sea ice drift is significantly enhanced close to the coast with lower-frequency wind forcing. Comparison with the observation off the Sakhalin coast shows that the degree of enhancement of sea ice drift and its characteristic such that larger enhancement occurs near the coast are mostly consistent with our theoretical solution, suggesting that this mechanism is present in the real ocean.

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Mao, Yadan, e Malcolm L. Heron. "The Influence of Fetch on the Response of Surface Currents to Wind Studied by HF Ocean Surface Radar". Journal of Physical Oceanography 38, n.º 5 (1 de maio de 2008): 1107–21. http://dx.doi.org/10.1175/2007jpo3709.1.

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Abstract The momentum transfer from wind to sea generates surface currents through both the wind shear stress and the Stokes drift induced by waves. This paper addresses issues in the interpretation of HF radar measurements of surface currents and momentum transfer from air to sea. Surface current data over a 30-day period from HF ocean surface radar are used to study the response of surface currents to wind. Two periods of relatively constant wind are identified—one for the short-fetch condition and the other for the long-fetch condition. Results suggest that the ratio of surface current speed to wind speed is larger under the long-fetch condition, while the angle between the surface current vector and wind vector is larger under the short-fetch condition. Data analysis shows that the Stokes drift dominates the surface currents under the long-fetch condition when the sea state is more mature, while the Stokes drifts and Ekman-type currents play almost equally important roles in the total currents under the short-fetch condition. The ratios of Stokes drift to wind speed under these two fetch conditions are shown to agree well with results derived from the empirical wave growth function. These results suggest that fetch, and therefore sea state, significantly influences the total response of surface current to wind in both the magnitude and direction by variations in the significance of Stokes drift. Furthermore, this work provides observational evidence that surface currents measured by HF radar include Stokes drift. It demonstrates the potential of HF radar in addressing the issue of momentum transfer from air to sea under various environmental conditions.

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3

Imai, Yuki, Junichi Ninomiya e Nobuhito Mori. "IMPACT OF RANDOM WAVE SPECTRA ON STOKES DRIFT IN COASTAL CURRENT MODELING". Coastal Engineering Proceedings, n.º 36 (30 de dezembro de 2018): 1. http://dx.doi.org/10.9753/icce.v36.currents.1.

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The wave-induced velocity, known commonly as Stokes drift, plays an important role on upper ocean current system. However, in general, the depth profile tends to be estimated using a regular wave approximation like calculation from significant wave height in order to simplify the modeling. Breivik et al. (2014) proposed an improved Stokes drift profile to considering random waves but discussed limited to deep water. This study proposes a novel treatment of Stokes drift on random waves to consider full directional spectra and the approximated treatment is introduced into coupled ocean-wave model to apply for the depth-limited region. To validate the proposed treatment, Stokes drift velocity derived from the treatment is theoretically and empirically compared with some derived from regular wave approximation. Finally coastal current simulation is performed for Kii channel of Japan focusing on Tanabe bay by the coupled model with two-way-nesting scheme.

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4

MUÑUZURI, A. P., V. PÉREZ-MUÑUZURI, M. GÓMEZ-GESTEIRA, V. I. KRINSKY e V. PÉREZ-VILLAR. "MECHANISM OF PARAMETRIC RESONANCE OF VORTICES IN EXCITABLE MEDIA". International Journal of Bifurcation and Chaos 04, n.º 05 (outubro de 1994): 1245–56. http://dx.doi.org/10.1142/s0218127494000939.

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An alternating electric current induces a drift of spiral waves (vortices) in the Belousov-Zhabotinsky reaction. When the electric current frequency is twice the frequency of the vortex rotation, the vortex drifts with a velocity about 1/5 of the vortex drift in a constant electric current or 1/20 of the wave front velocity. The dependence of parametric resonance on the chirality of the vortex, excitability of the medium, phase shift between electric current and vortex rotation, frequency and amplitude of the alternating electric current is analyzed and used to control the direction and velocity of the drift. A kinematical model, based on the asymmetric effect of the current on the normal and tangential velocities of the vortex tip, is formulated and recovers the most important aspects of parametric resonance.

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5

Hara, Hideo, Tomoki Joichi, Shunsuke Abe e Shin Masuda. "Photo-induced DC drift in Mach-Zehnder modulators using lead lanthanum zirconate titanate thin films". AIP Advances 12, n.º 12 (1 de dezembro de 2022): 125115. http://dx.doi.org/10.1063/5.0129414.

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We experimentally investigated the photo-induced direct current (DC) drift of a lead lanthanum zirconate titanate (PLZT) Mach-Zehnder modulator with large optical input power. We clarify the mechanism by which short-term and long-term DC drifts arise and discuss each case of DC drift. We reveal that short-term DC drift can be reduced by adjusting the buffer-layer resistivity of the PLZT modulator. We also found that the impurity level of the buffer layer affects long-term DC drift.

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6

Ahmad, Ali, e H. Saleem. "Current-driven electron drift solitons". Physics Letters A 377, n.º 43 (dezembro de 2013): 3128–30. http://dx.doi.org/10.1016/j.physleta.2013.07.061.

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7

Lee, Kwang-Ho, Tag-Gyeom Kim e Yong-Hwan Cho. "Influence of Tidal Current, Wind, and Wave in Hebei Spirit Oil Spill Modeling". Journal of Marine Science and Engineering 8, n.º 2 (22 de janeiro de 2020): 69. http://dx.doi.org/10.3390/jmse8020069.

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The purpose of this study is to investigate the effects of three external forces (tidal current, wind, and waves) on the movement of oil spilled during the Hebei Spirit oil spill accident. The diffusion of the spilled oil was simulated by using a random walk (RW) model that tracks the movement caused by advection-diffusion assuming oil as particles. For oil simulation, the wind drift current generated by wind and tidal current fields were computed by using the environmental fluid dynamics code (EFDC) model. Next, the wave fields were simulated by using the simulating waves nearshore (SWAN) model, and the Stokes drift current fields were calculated by applying the equation proposed by Stokes. The computed tidal currents, wind drift currents, and Stokes drift currents were applied as input data to the RW model. Then, oil diffusion distribution for each external force component was investigated and compared with that obtained from satellite images. When the wind drift currents and Stokes drift currents caused by waves were considered, the diffusion distribution of the spilled oil showed good agreement with that obtained from the observation.

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8

Sakurai, Guilherme Yukio, Jessica Fernandes Lopes, Bruno Bogaz Zarpelão e Sylvio Barbon Junior. "Benchmarking Change Detector Algorithms from Different Concept Drift Perspectives". Future Internet 15, n.º 5 (29 de abril de 2023): 169. http://dx.doi.org/10.3390/fi15050169.

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The stream mining paradigm has become increasingly popular due to the vast number of algorithms and methodologies it provides to address the current challenges of Internet of Things (IoT) and modern machine learning systems. Change detection algorithms, which focus on identifying drifts in the data distribution during the operation of a machine learning solution, are a crucial aspect of this paradigm. However, selecting the best change detection method for different types of concept drift can be challenging. This work aimed to provide a benchmark for four drift detection algorithms (EDDM, DDM, HDDMW, and HDDMA) for abrupt, gradual, and incremental drift types. To shed light on the capacity and possible trade-offs involved in selecting a concept drift algorithm, we compare their detection capability, detection time, and detection delay. The experiments were carried out using synthetic datasets, where various attributes, such as stream size, the amount of drifts, and drift duration can be controlled and manipulated on our generator of synthetic stream. Our results show that HDDMW provides the best trade-off among all performance indicators, demonstrating superior consistency in detecting abrupt drifts, but has suboptimal time consumption and a limited ability to detect incremental drifts. However, it outperforms other algorithms in detection delay for both abrupt and gradual drifts with an efficient detection performance and detection time performance.

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9

Ghaffari, Peygham, e Jan Erik H. Weber. "Mass Transport in the Stokes Edge Wave for Constant Arbitrary Bottom Slope in a Rotating Ocean". Journal of Physical Oceanography 44, n.º 4 (1 de abril de 2014): 1161–74. http://dx.doi.org/10.1175/jpo-d-13-0171.1.

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Abstract The Lagrangian mass transport in the Stokes surface edge wave is obtained from the vertically integrated equations of momentum and mass in a viscous rotating ocean, correct to the second order in wave steepness. The analysis is valid for bottom slope angles β in the interval 0 < β ≤ π/2. Vertically averaged drift currents are obtained by dividing the fluxes by the local depth. The Lagrangian mean current is composed of a Stokes drift (inherent in the waves) plus a mean Eulerian drift current. The latter arises as a balance between the radiation stresses, the Coriolis force, and bottom friction. Analytical solutions for the mean Eulerian current are obtained in the form of exponential integrals. The relative importance of the Stokes drift to the Eulerian current in their contribution to the Lagrangian drift velocity is investigated in detail. For the given wavelength, the Eulerian current dominates for medium and large values of β, while for moderate and small β, the Stokes drift yields the main contribution to the Lagrangian drift. Because most natural beaches are characterized by moderate or small slopes, one may only calculate the Stokes drift in order to assess the mean drift of pollution and suspended material in the Stokes edge wave. The main future application of the results for large β appears to be for comparison with laboratory experiments in rotating tanks.

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10

Fukamachi, Yasushi, Kay I. Ohshima, Yuji Mukai, Genta Mizuta e Masaaki Wakatsuchi. "Sea-ice drift characteristics revealed by measurement of acoustic Doppler current profiler and ice-profiling sonar off Hokkaido in the Sea of Okhotsk". Annals of Glaciology 52, n.º 57 (2011): 1–8. http://dx.doi.org/10.3189/172756411795931507.

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AbstractIn the southwestern part of the Sea of Okhotsk off Hokkaido, sea-ice drift characteristics are investigated using the ice and water velocities obtained from a moored upward-looking acoustic Doppler current profiler (ADCP) during the winters of 1999–2001. Using hourly-mean values of these data along with the wind data measured at a nearby coastal station, the wind factor and turning angle of the relative velocity between the ice and water velocities with respect to the wind are calculated assuming free drift under various conditions. Since the simultaneous sea-ice draft data are also available from a moored ice-profiling sonar (IPS), we examine the dependence of drift characteristics on ice thickness for the first time. As ice thickness increases and wind decreases, the wind factor decreases and the turning angle increases, as predicted by the theory of free drift. This study clearly shows the utility of the moored ADCP measurement for studying sea-ice drift, especially with the simultaneous IPS measurement for ice thickness, which cannot be obtained by other methods.

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Teses / dissertações sobre o assunto "Drift current"

1

Ridler, Emma Louise. "Wave-current interactions and drift velocities over rippled beds". Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624706.

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2

Stephens, Kenneth Frank. "Space-Charge Saturation and Current Limits in Cylindrical Drift Tubes and Planar Sheaths". Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2598/.

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Space-charge effects play a dominant role in many areas of physics. In high-power microwave devices using high-current, relativistic electron beams, it places a limit on the amount of radiation a device can produce. Because the beam's space-charge can actually reflect a portion of the beam, the ability to accurately predict the amount of current a device can carry is needed. This current value is known as the space-charge limited current. Because of the mathematical difficulties, this limit is typically estimated from a one-dimensional theory. This work presents a two-dimensional theory for calculating an upper-bound for the space-charge limited current of relativistic electron beams propagating in grounded coaxial drift tubes. Applicable to annular beams of arbitrary radius and thickness, the theory includes the effect introduced by a finite-length drift tube of circular cross-section. Using Green's second identity, the need to solve Poisson's equation is transferred to solving a Sturm-Liouville eigenvalue problem, which is easily solved by elementary methods. In general, the resulting eigenvalue, which is required to estimate the limiting current, must be numerically determined. However, analytic expressions can be found for frequently encountered limiting cases. Space-charge effects also produce the fundamental collective behavior found in plasmas, especially in plasma sheaths. A plasma sheath is the transition region between a bulk plasma and an adjacent plasma-facing surface. The sheath controls the loss of particles from the plasma in order to maintain neutrality. Using a fully kinetic theory, the problem of a planar sheath with a single-minimum electric potential profile is investigated. Appropriate for single charge-state ions of arbitrary temperature, the theory includes the emission of warm electrons from the surface as well as a net current through the sheath and is compared to particle-in-cell simulations. Approximate expressions are developed for estimating the sheath potential as well as the transition to space-charge saturation. The case of a space-charge limited sheath is discussed and compared to the familiar Child-Langmuir law.

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3

Gates, Dallas Cody. "Behavior of Flotsam in the California Current System Utilizing Surface Drift of RAFOS Floats". Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/17371.

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The patterns of surface drift of eighty-nine undrogued RAFOS floats in the California Current System have been studied. The floats were launched in the California Undercurrent during 19922010 and were tracked by the ARGOS system when they surfaced at the end of their subsurface mission. The surface drift of these floats was typically equatorward in the California Current. However, some floats moved poleward into the Subpolar Gyre, and others drifted westward into the North Equatorial Current. The duration of surface trajectories varied from as short as 11 days to as long as 280 days. Observations of surface currents typically use drifters which are coupled to the surface layer by drogues which are located at 15 m depth. While drogued observations are useful for studies of circulation of the upper layer of the ocean, a more typical operational problem involves trying to find flotsam that has fallen off the deck of a ship or to predict the path of a floating mine. To better understand the behavior of these surface drifting objects, observations of the surface drift of RAFOS floats in the California Current system were used to compare their motion to wind induced drift and evaluate the drift prediction by three ocean models, Ocean Surface Current Simulator (OSCURS), Global Navy Coastal Model (gNCOM) and Hybrid Coordinate Ocean Model (HYCOM). The results indicate that summer and fall months provided the best correlation between float drift speed and wind speed. Evaluation of the drift prediction by three ocean models was conducted by comparing observed drifter trajectories with model simulated trajectories at 7-day timescales. The model-simulated trajectories were initially collocated with RAFOS positions and restarted every 15 days. These results showed that OSCURS was able to give better short-term prediction of surface drift than gNCOM and HYCOM when OSCURS model parameters were chosen as to minimize separation between modeled and observed trajectories.

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4

Kovac, Urban. "3D drift diffusion and 3D Monte Carlo simulation of on-current variability due to random dopants". Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/2309/.

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In this work Random Discrete Dopant induced on-current variations have been studied using the Glasgow 3D atomistic drift/diffusion simulator and Monte Carlo simulations. A methodology for incorporating quantum corrections into self-consistent atomistic Monte Carlo simulations via the density gradient effective potential is presented. Quantum corrections based on the density gradient formalism are used to simultaneously capture quantum confinement effects. The quantum corrections not only capture charge confinement effects, but accurately represent the electron impurity interaction used in previous \textit{ab initio} atomistic MC simulations, showing agreement with bulk mobility simulation. The effect of quantum corrected transport variation in statistical atomistic MC simulation is then investigated using a series of realistic scaled devices nMOSFETs transistors with channel lengths 35 nm, 25 nm, 18nm, 13 nm and 9 nm. Such simulations result in an increased drain current variability when compared with drift diffusion simulation. The comprehensive statistical analysis of drain current variations is presented separately for each scaled transistor. The investigation has shown increased current variation compared with quantum corrected drift diffusion simulation and with previous classical MC results. Furthermore, it has been studied consistently the impact of transport variability due to scattering from random discrete dopants on the on-current variability in realistic nano CMOS transistors. For the first time, a hierarchic simulation strategy to accurately transfer the increased on-current variability obtained from the ‘ab initio’ MC simulations to DD simulations is subsequently presented. The MC corrected DD simulations are used to produce target $I_D-V_G$ characteristics from which statistical compact models are extracted for use in preliminary design kits at the early stage of new technology development. The impact of transport variability on the accuracy of delay simulation are investigated in detail. Accurate compact models extraction methodology transferring results from accurate physical variability simulation into statistical compact models suitable for statistical circuit simulation is presented. In order to examine te size of this effect on circuits Monte Carlo SPICE simulations of inverter were carried out for 100 samples.

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5

Engelbrecht, Nicholas Eugéne. "On the development and applications of a three-dimensional ab initio cosmic-ray modulation model / Nicholas Eugéne Engelbrecht". Thesis, North-West University, 2012. http://hdl.handle.net/10394/8735.

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A proper understanding of the effects of turbulence on the diffusion and drift of cosmic-rays in the heliosphere is imperative for a better understanding of cosmic-ray modulation. This study presents an ab initio model for cosmic-ray modulation, incorporating for the first time the results yielded by a two-component turbulence transport model. The latter model is solved for solar minimum heliospheric conditions, utilizing boundary values chosen in such a way that the results of this model are in fair to good agreement with spacecraft observations of turbulence quantities, not only in the ecliptic plane, but also along the out-of-ecliptic trajectory of the Ulysses spacecraft. These results are employed as inputs for modelled slab and 2D turbulence energy spectra, which in turn are used as inputs for parallel mean free paths based on those derived from quasi-linear theory, and perpendicularmean free paths from extended nonlinear guiding center theory. The modelled 2D spectrum is chosen based on physical considerations, with a drop-off at the very lowest wavenumbers commencing at the 2D outerscale. There currently exist no models or observations for this quantity, and it is the only free parameter in this study. The use of such a spectrum yields a non-divergent 2D ultrascale, which is used as an input for the reduction terms proposed to model the effects of turbulence on cosmic-ray drifts. The resulting diffusion and drift coefficients are applied to the study of galactic cosmic-ray protons, electrons, antiprotons, and positrons using a three-dimensional, steady-state numerical cosmic-ray modulation code. The magnitude and spatial dependence of the 2D outerscale is demonstrated to have a significant effect on computed cosmic-ray intensities. A form for the 2D outerscale was found that resulted in computed cosmic-ray intensities, for all species considered, in reasonable agreement with multiple spacecraft observations. Computed galactic electron intensities are shown to be particularly sensitive to choices of parameters pertaining to the dissipation range of the slab turbulence spectrum, and certain models for the onset wavenumber of the dissipation range could be eliminated in this study.
Thesis (PhD (Physics))--North-West University, Potchefstroom Campus, 2013

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Yamamoto, Kazuhiro. "Excitation of High-m Poloidal ULF Waves in the Inner Magnetosphere during Geomagnetic Storms and Substorms: Importance of Radial Gradient of Proton Distributions in Drift-Bounce Resonance". Kyoto University, 2020. http://hdl.handle.net/2433/253099.

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7

Chilton, Kristin Danielle. "Terrigenous Grain-Size Record of the Newfoundland Ridge Contourite Drift, IODP Site U1411: The First Physical Proxy Record of North Atlantic Abyssal Current Intensity during the Eocene-Oligocene Transition". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/83539.

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Atlantic Meridional Overturning Circulation (AMOC) is a vital process that transfers heat and nutrients throughout the world's oceans, helping to regulate global climate and support marine ecosystems. The timing and nature of the shift to modern AMOC, and especially to deep-water formation in the North Atlantic, has been a topic of ongoing study, with the Eocene-Oligocene Transition (EOT, ~34 Ma) as a potential focal point of this shift. However, the role played by abrupt EOT cooling and Antarctic glaciation in North Atlantic circulation remains unclear. Improved constraints on Paleogene circulation will provide insight into the sensitivity of AMOC to perturbations in global climate, which is particularly relevant in light of contemporary climate change. To examine deep North Atlantic circulation response to the EOT we obtained grain-size data from the terrigenous fraction of the mud-dominated sediments of the Southeast Newfoundland Ridge contourite drift complex at IODP Site U1411, which is interpreted to have formed under the influence of the Deep Western Boundary Current. We analyzed 195 samples that span 150 m of stratigraphy from 36-26 Ma. The main objective was to use the 'sortable silt' fraction (10-63 µm) to generate a record of relative change in bottom-current intensity. These data are complemented with a record of the abundance and size of lithogenic sand (>63 µm). Here we present the first physical proxy record of abyssal current intensity in the North Atlantic, from late Eocene to mid Oligocene. Invigoration of North Atlantic deep circulation occurred gradually (over Myr timescales), with no significant changes linked temporally to the EOT. We infer that deep circulation in the North Atlantic was not sensitive to the abrupt global cooling and Antarctic glaciation associated with the EOT. Rather, our data suggest that changes in North Atlantic circulation were likely governed by longer-term processes related to the opening of key tectonic gateways, such as the Greenland-Scotland Ridge in the North Atlantic, and the Drake and Tasman Passages in the Southern Ocean. Additionally, we identify a significant mid-Oligocene invigoration of North Atlantic abyssal circulation, which climaxes around 27.9 Ma, and is coeval with a decrease in atmospheric CO2.
Master of Science

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8

Ahmed, Mustafa M. Abdalla. "Alternating-Current Thin-Film Electroluminescent Device Characterization". Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-233432.

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Jádrem této disertační práce bylo studovat optické a elektrické charakteristiky tenkovrstvých elektroluminiscenčních součástek řízených střídavým proudem (ACTFEL) a zejména vliv procesu stárnutí luminiforů na jejich optické a elektrické vlastnosti. Cílem této studie měl být příspěvek ke zvýšení celkové účinnosti luminoforů, vyjádřené pomocí jasu, účinnosti a stability. Vzhledem k tomu, že současnou dominantní technologií plochých obrazovek je LCD, musí se další alternativní technologie plošných displejů porovnávat s LCD. Výhodou ACTFEL displejů proti LCD je lepší rozlišení, větší teplotní rozsah činnosti, větší čtecí úhel, či možnost čtení při mnohem vyšší intenzitě pozadí. Na druhou stranu je jejich nevýhodou vyšší energetická náročnost, problém s odpovídající barevností tří základních barev a podstatně vyšší napětí nutné pro činnost displeje. K dosažení tohoto cíle jsme provedli optická, elektrická a optoelektrická měření ACTFEL struktur a ZnS:Mn luminoforů. Navíc jsme studovali vliv dotování vrstvy pomocí KCl na chování mikrostruktury a na elektroluminiscenční vlastnosti (zejména na jas a světelnou účinnost) ZnS:Mn luminoforů. Provedli jsme i některá, ne zcela obvyklá, měření ACTFEL součástek. Vypočítali jsme i rozptylový poměr nabitých barevných center a simulovali transportní charakteristiky v ACTFEL součástkách. Studovali jsme vliv stárnutí dvou typů ZnS:Mn luminoforů (s vrstvou napařenou či získanou pomocí epitaxe atomových vrstev) monitorováním závislostí svítivost-napětí (L-V), velikost vnitřního náboje - elektrické pole luminoforu (Q-Fp) a kapacitance-napětí (C-V) ve zvolených časových intervalech v průběhu stárnutí. Provedli jsme krátkodobá i dlouhodobá měření a pokusili jsme se i o vizualizaci struktury luminoforu se subvlnovým rozlišením pomocí optického rastrovacího mikroskopu pracujícího v blízkém poli (SNOM). Na praktickém případu zeleného Zn2GeO4:Mn (2% Mn) ACTFEL displeje, pracujícího při 50 Hz, jsme také studovali stabilitu svítivosti pomocí měření závislosti svítivosti na napětí (L-V) a světelné účinnosti na napětí (eta-V). Přitom byl zhodnocen význam těchto charakteristik. Nezanedbatelnou a neoddělitelnou součástí této práce je i její pedagogický aspekt. Předložený text by mohl být využit i jako učebnice pro studenty na mé univerzitě v Lybii.

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9

Church, John Casey. "Topics in longshore currents". Thesis, Monterey, Calif. : Naval Postgraduate School, 1993. http://catalog.hathitrust.org/api/volumes/oclc/29749880.html.

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10

Cure, Marcel Serge. "Langmuir circulation : a side-scan sonar study of mixing in Loch Ness". Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240617.

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Mais fontes

Livros sobre o assunto "Drift current"

1

1922-, Leuchtenburg William Edward, ed. Drift and mastery: An attempt to diagnose the current unrest. Madison, Wis: University of Wisconsin Press, 1985.

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2

Institute, American Law, ed. Uniform commercial code current payment methods: Council draft. Philadelphia, Pa: Executive Office, American Law Institute, 1989.

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3

Russell, Sarah L. Shelf currents, ice and wind: A numeric modeling study. Cambridge, Mass: Massachusetts Institute of Technology, 2003.

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4

Rosati, Julie Dean. Superduck surf zone sand transport experiment. [Vicksburg, Miss: U.S. Army Engineer Waterways Experiment Station, 1990.

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5

Rosati, Julie Dean. Superduck surf zone sand transport experiment. [Vicksburg, Miss: U.S. Army Engineer Waterways Experiment Station, 1990.

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6

Richardson, Philip L. Surface velocity in the equatorial oceans (20N-20S) calculated from historical ship drifts. Woods Hole, Mass: Woods Hole Oceanographic Institution, 1989.

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7

Sherlock, Ann R. A user's guide to the Littoral Environment Observation Retrieval System. [Vicksburg, Miss: U.S. Army Engineer Waterways Experiment Station, 1987.

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8

Zambia, Caritas, ed. Caritas Zambia analysis of the current and the Mung'omba draft constitution. Lusaka]: [Caritas Zambia], 2006.

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Zambia, Caritas, ed. Caritas Zambia analysis of the current and the Mung'omba Draft Constitution. Lusaka: Caritas Zambia, 2007.

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Great Britain. Department for Constitutional Affairs. Draft Single European Currency (Referendum) Bill & explanatory notes. Norwich: TSO, 2003.

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Mais fontes

Capítulos de livros sobre o assunto "Drift current"

1

Menkhoff, Lukas, e Norbert Tolksdorf. "Current empirical studies of decoupling characteristics". In Financial Market Drift, 65–122. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56581-6_3.

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Knights, Dan, Mike Mozer e Nicolas Nicolov. "Detecting topic drift". In Current Issues in Linguistic Theory, 113–30. Amsterdam: John Benjamins Publishing Company, 2009. http://dx.doi.org/10.1075/cilt.309.09kni.

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Armstrong, Thomas P., Mark E. Pesses e Robert B. Decker. "Shock drift acceleration". In Collisionless Shocks in the Heliosphere: Reviews of Current Research, 271–85. Washington, D. C.: American Geophysical Union, 1985. http://dx.doi.org/10.1029/gm035p0271.

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4

Huijsmans, R. H. M. "Slowly Varying Wave Drift Forces in Current". In Nonlinear Water Waves, 283–91. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-83331-1_31.

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Malova, Helmi V., Mikhail I. Sitnov, Lev M. Zelenyi e Surja Sharma. "Self-consistent model of 1D current sheet: The role of drift, magnetization and diamagnetic currents". In Magnetospheric Current Systems, 313–22. Washington, D. C.: American Geophysical Union, 2000. http://dx.doi.org/10.1029/gm118p0313.

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Reintges, Chris H. "Sapirian ‘drift’ towards analyticity and long-term morphosyntactic change in Ancient Egyptian". In Current Issues in Linguistic Theory, 289–328. Amsterdam: John Benjamins Publishing Company, 2013. http://dx.doi.org/10.1075/cilt.326.19rei.

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Bandyopadhyay, Supriyo. "Charge and Current in Solids: The Classical Drift–Diffusion Model". In Physics of Nanostructured Solid State Devices, 1–33. Boston, MA: Springer US, 2012. http://dx.doi.org/10.1007/978-1-4614-1141-3_1.

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Patrick, Edward, Douglas Abner, David Ramos, Merrill Andrews e Alan Garscadden. "Geometry-Dependent Displacement Current in the Pulsed-Townsend Drift Tube". In Nonequilibrium Effects in Ion and Electron Transport, 453–54. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0661-0_66.

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De Keyset, J. "Storm-time energetic particle penetration into the inner magnetosphere as the electromotive force in the subauroral ion drift current circuit". In Magnetospheric Current Systems, 261–65. Washington, D. C.: American Geophysical Union, 2000. http://dx.doi.org/10.1029/gm118p0261.

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Lehner, M. J., T. B. Lawson, C. J. Martoff, D. Snowden-Ifft, N. J. C. Spooner, K. Griest, T. Gamble et al. "Current Status of the DRIFT Project and UKDMC Dark Matter Search". In Dark Matter in Astro- and Particle Physics, 590–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56643-1_54.

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Trabalhos de conferências sobre o assunto "Drift current"

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Peng, Yujia, Huixiang Huang e Rongrong Guo. "Research on the influence of illumination on the leakage current of silicon drift detectors". In Third International Conference on Electronics Technology and Artificial Intelligence (ETAI 2024), editado por Feng Yin e Zehui Zhan, 3. SPIE, 2024. http://dx.doi.org/10.1117/12.3044961.

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Bolin, Shuai, Wang Ziou e Guan Xiaojin. "Body current model for Drift Drain Mosfet". In 2006 8th International Conference on Solid-State and Integrated Circuit Technology Proceedings. IEEE, 2006. http://dx.doi.org/10.1109/icsict.2006.306159.

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Stansberg, Carl Trygve, Jan Roger Hoff, Elin Marita Hermundstad e Rolf Baarholm. "Wave Drift Forces and Responses in Current". In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11407.

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The influence from a current on wave drift forces and resulting slowly varying vessel responses can be quite significant. In this paper the effect is reviewed and further investigated. Several works have been published on this complex topic during the last 20–25 years, while it is only to a little extent taken consistently into account in standard industry tools. Simplified methods are often used, if any, and /or empirical correction from model test data. Thus there is a need to improve standard tools in this respect. The effects on slowly varying vessel motions and resulting extreme mooring line loads are demonstrated through time series sequences from selected, previous model tests with FPSO’s and semisubmersibles in steep irregular waves. Wave-current interaction effects that can be larger than the effects from current and wind alone are identified. It is also confirmed from these examples that extreme mooring forces usually occur due to extreme slow-drift motions. An overview description is given of a new, general numerical potential theory code for industry use, MULDIF-2, where wave-current-structure interaction is consistently included as a basic element in the formulation. Main items in the approach are addressed and referred to previous works in the literature. Results from an initial comparison against previous results on drift forces on a vertical column are given, and a good agreement is found. Further verification and validation work is in progress.

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Yu, Ya-Lei, Jia-Hong Wang e Wan-Zheng Ai. "Research on fishing vessel drift movement in current". In The 2015 International Conference on Design, Manufacturing and Mechatronics (ICDMM2015). WORLD SCIENTIFIC, 2015. http://dx.doi.org/10.1142/9789814730518_0171.

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Amador, Andre, Geno Pawlak e Sergio Jaramillo. "ADCP bias and stokes drift in AUV-based measurements". In 2015 IEEE/OES Eleventh Current, Waves and Turbulence Measurement (CWTM). IEEE, 2015. http://dx.doi.org/10.1109/cwtm.2015.7098146.

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Liren, Zhou, Pan Yang e Zhu Li. "Sensitivity and drift value measurement of DC current comparator". In 2019 14th IEEE International Conference on Electronic Measurement & Instruments (ICEMI). IEEE, 2019. http://dx.doi.org/10.1109/icemi46757.2019.9101759.

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Kalinić, Ana, Ivan Radović, Lazar Karbunar e Z. L. Mišković. "INTERACTION OF IONS WITH DRIFT-CURRENT BIASED SUPPORTED GRAPHENE". In 32nd SUMMER School and International Symposium on the Physics of Ionized Gases, 80. Astronomical Observatory Belgrade, Volgina 7, 11060 Belgrade 38, Serbia, 2024. http://dx.doi.org/10.69646/aob103p080.

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Ommani, Babak, Nuno Fonseca e Carl Trygve Stansberg. "Simulation of Low Frequency Motions in Severe Seastates Accounting for Wave-Current Interaction Effects". In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62550.

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Today’s industry practice assumes wave drift forces on floating structures can be computed from zero current wave drift force coefficients for the stationary floater, while simplified correction models introduce current effects and slow drift velocity effects. The paper presents an alternative approach which overcomes some of the limitations of today’s procedures. The method, to be applied together with a time domain solution of the low frequency motions, is based on pre-calculation of mean wave drift force coefficients for a range of current velocities. During the low frequency motions simulation, the wave drift forces induced by the irregular waves are computed from the mean drift coefficients corresponding to instantaneous relative velocity resulting from the current and the low frequency velocities. A simple interpolation model, based on a quasi-steady assumption, is applied to obtain the drift forces in time-domain. Since calculation of the wave drift forces on Semi-submersibles in severe sea states with fully consistent methods is out of reach, a semi-empirical model is applied to correct the potential flow wave drift force coefficients. This model takes into account viscous effects, that are important in high seastates, and wave-current interaction effects. The paper compares the wave drift forces and the related low frequency motions computed by the proposed method, with results applying “standard” methods and with model test data. The test data was obtained in the scope of the EXWAVE JIP, with model tests designed to investigate wave drift forces in severe seastates and assess the wave-current interaction effects.

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Dussol, Abigaelle, Cedric Chavanne e Dany Dumont. "Wave-Induced Stokes Drift Measurement by High-Frequency Radars: Preliminary Results". In 2019 IEEE/OES Twelfth Current, Waves and Turbulence Measurement (CWTM). IEEE, 2019. http://dx.doi.org/10.1109/cwtm43797.2019.8955276.

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Hermundstad, Elin Marita, Jan Roger Hoff, Carl Trygve Stansberg e Rolf Baarholm. "Effects of Wave-Current Interaction on Floating Bodies". In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54868.

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Wave-current interaction effects may significantly influence the mean wave drift forces on a structure as well as the motion responses and wave elevation around the structure. Additionally, the drift force may be used to estimate the wave drift damping of a moored structure. A new numerical potential theory code for industry applications (MULDIF) has been recently developed, where the hydrodynamic interaction between waves and current of arbitrary direction with large volume structures is consistently included. The code also handles multiple bodies and finite water depth including wave-current interaction effects. The aim has been to create a robust and easy-to-use practical tool. Initial validation studies against model tests have been conducted. The numerical results show a strong heave-pitch coupling due to the presence of the current. Preliminary results for a semi-submersible show good agreement for the motions provided that the mooring used in the model tests are accounted for. The free surface elevation around the semi-submersible is presented in contour plots.

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Relatórios de organizações sobre o assunto "Drift current"

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T.A. Carter, H. Ji, F. Trintchouk, M. Yamada e R.M. Kulsrud. Measurement of Lower-hybrid Drift Turbulence in a Reconnecting Current Sheet. Office of Scientific and Technical Information (OSTI), junho de 2001. http://dx.doi.org/10.2172/787682.

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2

Carter, T. A., M. Yamada, H. Ji, R. M. Kulsrud e F. Trintchouck. Experimental Study of Lower-hybrid Drift Turbulence in a Reconnecting Current Sheet. Office of Scientific and Technical Information (OSTI), junho de 2002. http://dx.doi.org/10.2172/798197.

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Andrews, Madison, e Austin Mullen. DRiFT Current Mode, Trigger Settings and Flexible Detector Specifications Applied to Scintillator Arrays. Office of Scientific and Technical Information (OSTI), junho de 2024. http://dx.doi.org/10.2172/2377691.

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McHale, Yalin e Olsen. PR-179-13203-R01 Real Time Laser Sensor for Nitrogen Oxides and Carbon Monoxide. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), agosto de 2014. http://dx.doi.org/10.55274/r0010020.

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Performance of current NOx sensors is problematic, in particular drift and cross-sensitivity to other species. Many lean burn engines are operated based on earlier calibrations. Operators must allow for drift and use large margins to meet emissions. Laser sensors (based on absorption at target wavelengths) are self-calibrating and immune to interferences. In particular, recently developed Quantum Cascade Lasers (QCLs) allow measurements at mid-infrared (MIR) wavelengths thereby allowing stronger signals, better schemes to mitigate interferences, and fast time response. This project evaluated a commercial QCL-based NOx (NO, NO2) and CO sensor for use in gas engine applications. The project also developed and performed bench top testing of a custom sensor which uses a �pitch and catch� design.

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Ramsey, Andree L., Heather H. Furey e Amy S. Bower. Overturning of the Subpolar North Atlantic Program (OSNAP): RAFOS Float Data Report June 2014 - January 2019. Woods Hole Oceanographic Institution, dezembro de 2022. http://dx.doi.org/10.1575/1912/29540.

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The Overturning in the Subpolar North Atlantic Program (OSNAP) is an international effort started in 2014 dedicated to achieving a better understanding of the link between dense-water formation and the meridional overturning circulation in the high-latitude North Atlantic. Moorings, gliders, and subsurface acoustically-tracked RAFOS floats have been used to collect temperature, salinity, and current data across the Labrador Sea, Irminger Sea, Reykjanes Ridge, Iceland Basin, Rockall-Hatton Plateau, and Rockall Trough. The specific objective of the OSNAP float program is to gather information on the pathways of the dense overflow waters transported by the deep limb of the overturning circulation and assess the connection of those pathways with currents observed crossing the OSNAP mooring line. This data report details the observations collected by 148 floats that were deployed for OSNAP during the summers of 2014, 2015, 2016 and 2017. Deployment locations were in the Iceland Basin, Irminger Sea, and in the Charlie-Gibbs Fracture Zone. Mission lengths ranged from 540-730 days, and the floats were ballasted to passively drift at a fixed pressure of either 1800, 2000, 2200, 2500, or 2800 dbar to tag the deep overflow water masses of the subpolar North Atlantic (Iceland-Scotland and Denmark Strait Overflow Waters).

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Huntley, D., D. Rotheram-Clarke, R. Cocking, J. Joseph e P. Bobrowsky. Current research on slow-moving landslides in the Thompson River valley, British Columbia (IMOU 5170 annual report). Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/331175.

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Interdepartmental Memorandum of Understanding (IMOU) 5170 between Natural Resources Canada (NRCAN), the Geological Survey of Canada (GSC) and Transport Canada Innovation Centre (TC-IC) aims to gain new insight into slow-moving landslides, and the influence of climate change, through testing conventional and emerging monitoring technologies. IMOU 5107 focuses on strategically important sections of the national railway network in the Thompson River valley, British Columbia (BC), and the Assiniboine River valley along the borders of Manitoba (MN) and Saskatchewan (SK). Results of this research are applicable elsewhere in Canada (e.g., the urban-rural-industrial landscapes of the Okanagan Valley, BC), and around the world where slow-moving landslides and climate change are adversely affecting critical socio-economic infrastructure. Open File 8931 outlines landslide mapping and changedetection monitoring protocols based on the successes of IMOU 5170 and ICL-IPL Project 202 in BC. In this region, ice sheets, glaciers, permafrost, rivers and oceans, high relief, and biogeoclimatic characteristics contribute to produce distinctive rapid and slow-moving landslide assemblages that have the potential to impact railway infrastructure and operations. Bedrock and drift-covered slopes along the transportation corridors are prone to mass wasting when favourable conditions exist. In high-relief mountainous areas, rapidly moving landslides include rock and debris avalanches, rock and debris falls, debris flows and torrents, and lahars. In areas with moderate to low relief, rapid to slow mass movements include rockslides and slumps, debris or earth slides and slumps, and earth flows. Slow-moving landslides include rock glaciers, rock and soil creep, solifluction, and lateral spreads in bedrock and surficial deposits. Research efforts lead to a better understanding of how geological conditions, extreme weather events and climate change influence landslide activity along the national railway corridor. Combining field-based landslide investigation with multi-year geospatial and in-situ time-series monitoring leads to a more resilient railway national transportation network able to meet Canada's future socioeconomic needs, while ensuring protection of the environment and resource-based communities from landslides related to extreme weather events and climate change. InSAR only measures displacement in the east-west orientation, whereas UAV and RTK-GNSS change-detection surveys capture full displacement vectors. RTK-GNSS do not provide spatial coverage, whereas InSAR and UAV surveys do. In addition, InSAR and UAV photogrammetry cannot map underwater, whereas boat-mounted bathymetric surveys reveal information on channel morphology and riverbed composition. Remote sensing datasets, consolidated in a geographic information system, capture the spatial relationships between landslide distribution and specific terrain features, at-risk infrastructure, and the environmental conditions expected to correlate with landslide incidence and magnitude. Reliable real-time monitoring solutions for critical railway infrastructure (e.g., ballast, tracks, retaining walls, tunnels, and bridges) able to withstand the harsh environmental conditions of Canada are highlighted. The provision of fundamental geoscience and baseline geospatial monitoring allows stakeholders to develop robust risk tolerance, remediation, and mitigation strategies to maintain the resilience and accessibility of critical transportation infrastructure, while also protecting the natural environment, community stakeholders, and Canadian economy. We propose a best-practice solution involving three levels of investigation to describe the form and function of the wide range of rapid and slow-moving landslides occurring across Canada that is also applicable elsewhere. Research activities for 2022 to 2025 are presented by way of conclusion.

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Meshkat, N. Beam Aborts in PEP-II Rings and Lingering Drift Chamber Currents. Office of Scientific and Technical Information (OSTI), setembro de 2004. http://dx.doi.org/10.2172/833114.

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Rognlien, T. D., J. L. Milovich e M. E. Rensink. Modeling cross-field drifts and current with the B2 code for the CIT divertor. Office of Scientific and Technical Information (OSTI), outubro de 1990. http://dx.doi.org/10.2172/6472875.

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Hammad, Ali, e Mohamed Moustafa. Seismic Behavior of Special Concentric Braced Frames under Short- and Long-Duration Ground Motions. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, dezembro de 2019. http://dx.doi.org/10.55461/zont9308.

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Over the past decade, several long-duration subduction earthquakes took place in different locations around the world, e.g., Chile in 2010, Japan in 2011, China in 2008, and Indonesia in 2004. Recent research has revealed that long-duration, large-magnitude earthquakes may occur along the Cascadia subduction zone of the Pacific Northwest Coast of the U.S. The duration of an earthquake often affects the response of structures. Current seismic design specifications mostly use response spectra to identify the hazard and do not consider duration effects. Thus, a comprehensive understanding of the effect of the duration of the ground motion on structural performance and its design implications is an important issue. The goal of this study was to investigate how the duration of an earthquake affects the structural response of special concentric braced frames (SCBFs). A comprehensive experimental program and detailed analytical investigations were conducted to understand and quantify the effect of duration on collapse capacity of SCBFs, with the goal of improving seismic design provisions by incorporating these effects. The experimental program included large-scale shake table tests, and the analytical program consisted of pre-test and post-test phases. The pre-test analysis phase performed a sensitivity analysis that used OpenSees models preliminarily calibrated against previous experimental results for different configuration of SCBFs. A tornado-diagram framework was used to rank the influence of the different modeling parameters, e.g., low-cycle fatigue, on the seismic response of SCBFs under short- and long-duration ground motions. Based on the results obtained from the experimental program, these models were revisited for further calibration and validation in the post-test analysis. The experimental program included three large-scale shake-table tests of identical single-story single-bay SCBF with a chevron-brace configuration tested under different ground motions. Two specimens were tested under a set of spectrally-matched short and long-duration ground motions. The third specimen was tested under another long-duration ground motion. All tests started with a 100% scale of the selected ground motions; testing continued with an ever-increasing ground-motion scale until failure occurred, e.g., until both braces ruptured. The shake table tests showed that the duration of the earthquake may lead to premature seismic failure or lower capacities, supporting the initiative to consider duration effects as part of the seismic design provisions. Identical frames failed at different displacements demands because of the damage accumulation associated with the earthquake duration, with about 40% reduction in the displacement capacity of the two specimens tested under long-duration earthquakes versus the short-duration one. Post-test analysis focused first on calibrating an OpenSees model to capture the experimental behavior of the test specimens. The calibration started by matching the initial stiffness and overall global response. Next, the low-cycle fatigue parameters were fine-tuned to properly capture the experimental local behavior, i.e., brace buckling and rupture. The post-test analysis showed that the input for the low-cycle fatigue models currently available in the literature does not reflect the observed experimental results. New values for the fatigue parameters are suggested herein based on the results of the three shake-table tests. The calibrated model was then used to conduct incremental dynamic analysis (IDA) using 44 pairs of spectrally-matched short- and long-duration ground motions. To compare the effect of the duration of ground motion, this analysis aimed at incorporating ground-motion variability for more generalized observations and developing collapse fragility curves using different intensity measures (IMs). The difference in the median fragility was found to be 45% in the drift capacity at failure and about 10% in the spectral acceleration (Sa). Using regression analysis, the obtained drift capacity from analysis was found to be reduced by about 8% on average for every additional 10 sec in the duration of the ground motion. The last stage of this study extended the calibrated model to SCBF archetype buildings to study the effect of the duration of ground motion on full-sized structures. Two buildings were studied: a three-story and nine-story build that resembled the original SAC buildings but were modified with SCBFs as lateral support system instead of moment resisting frames. Two planer frames were adopted from the two buildings and used for the analysis. The same 44 spectrally-matched pairs previously used in post-test analysis were used to conduct nonlinear time history analysis and study the effect of duration. All the ground motions were scaled to two hazard levels for the deterministic time history analysis: 10% exceedance in 50 years and 2% exceedance in 50 years. All analysis results were interpreted in a comparative way to isolate the effect of duration, which was the main variable in the ground-motion pairs. In general, the results showed that the analyzed SCBFs experienced higher drift values under the long-duration suite of ground motions, and, in turn, a larger percentage of fractured braces under long-duration cases. The archetype SCBFs analysis provided similar conclusions on duration effects as the experimental and numerical results on the single-story single-bay frame.

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McCarthy, James, e Wendy Coulson. PR-312-17204-R01 Portable Analyzer Method Update - Phase 2. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), setembro de 2018. http://dx.doi.org/10.55274/r0011520.

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This report provides status and results after completing Phase 2 of an ongoing project to develop a simplified test method for portable analyzer emissions tests. The Phase 1 report provided the technical rationale for simplifying procedures (e.g., calibration) and reducing associated costs based on the inherent linearity associated with the physical properties of electrochemical cells, which are the analytical technology used in current generation electrochemical analyzers. The Phase 1 report also identified the primary criteria for the simplified methodology. This document provides a listing of related PRCI project documents, including the project plan, the draft test method, and the data gaps memo. The main focus of this report is to present results of lab and field experimentation conducted in 2016 and 2017 designed to address the data gaps. Portable analyzer manufacturers (Testo, AMETEK, and ECOM) demonstrated support for this project via cofounding and participation in experimentation and draft method discussions. The conclusions drawn from the experimentation in support of draft method revisions will be discussed in greater detail in the final report.

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