Influence of Filter Frequency Dispersion on Soliton Arrival Time Jitter

1996 ◽  
Vol 2 (2) ◽  
pp. 134-142
Author(s):  
Thierry Georges ◽  
Benoı̂t Charbonnier ◽  
François Favre
Keyword(s):  
Arrival Time ◽  
Frequency Dispersion ◽  
Time Jitter ◽  
Filter Frequency

scholarly journals TSUNAMI PHASE SPEED REDUCTION DUE TO WATER COMPRESSIBILTY

2018 ◽  
pp. 9
Author(s):  
Ali Abdolali ◽  
James T. Kirby
Keyword(s):  
Arrival Time ◽  
Phase Speed ◽  
Propagation Speed ◽  
Frequency Dispersion ◽  
Wave Theory ◽  
Polar Coordinates ◽  
Ocean Bottom ◽  
Tsunami Propagation ◽  
Boussinesq Model ◽  
Tsunami Waves

Most existing tsunami propagation models consider the ocean to be an incompressible, homogenous medium. Recently, it has been shown that a number of physical features can slow the propagation speed of tsunami waves, including wave frequency dispersion, ocean bottom elasticity, water compressibility and thermal or salinity stratification. These physical effects are secondary to the leading order, shallow water or long wave behavior, but still play a quantifiable role in tsunami arrival time, especially at far distant locations. In this work, we have performed analytical and numerical investigations and have shown that consideration of those effects can actually improve the prediction of arrival time at distant stations, compared to incompressible forms of wave equations. We derive a modified Mild Slope Equation for Weakly Compressible fluid following the method proposed by Sammarco et al. (2013) and Abdolali et al. (2015) using linearized wave theory, and then describe comparable extensions to the Boussinesq model of Kirby et al. (2013). Both models account for water compressibility and compression of static water column to simulate tsunami waves. The mild slope model is formulated in plane Cartesian coordinates and is thus limited to medium propagation distances, while the Boussinesq model is formulated in spherical polar coordinates and is suitable for ocean scale simulations.

Ocean Swell: How Much Do We Know

2017 ◽  
Author(s):  
Alexander V. Babanin ◽  
Haoyu Jiang
Keyword(s):  
Wave Amplitude ◽  
Arrival Time ◽  
Frequency Dispersion ◽  
Nonlinear Effects ◽  
Joint Analysis ◽  
Wave Forecast ◽  
Model Predictions ◽  
Forecast Models ◽  
Maritime Operations ◽  
Definition Of

Swell waves are present in more than 80% of ocean seas, and provide significant adverse impact on maritime operations. Their prediction by wave-forecast models, however, is poor, both in terms of wave amplitude and, particularly, arrival time. The very definition of ocean swell is ambiguous: while it is usually perceived as former wind-generated waves, in fact it may reconnect with the local wind through nonlinear interactions. The paper will bring together an overview of the complex swell problem. The visible swell attenuation is driven by a number of dissipative and non-dissipative processes. The dissipative phenomena include interaction with turbulence on the water and air sides, with adverse winds or currents. Non-dissipative contributions to the gradual decline of wave amplitude come from frequency dispersion, directional spreading, refraction by currents, and lateral diffraction of wave energy. The interactions with local winds/waves can, on the contrary, cause swell growth. Swell arrival time is the least understood and the most uncertain problem. Joint analysis of buoy observations and model reanalysis shows that swell can be tens of hours early or late by comparison with model predictions. Linear and nonlinear effects which can contribute to such biases are discussed.

Wave Dispersion Effect in the Indian Ocean Tsunami

2006 ◽  
Vol 1 (1) ◽  
pp. 142-147 ◽  
Author(s):  
Yoshinori Shigihara ◽  
◽  
Koji Fujima
Keyword(s):  
Indian Ocean ◽  
Arrival Time ◽  
Frequency Dispersion ◽  
Wave Dispersion ◽  
Tsunami Source ◽  
Indian Ocean Tsunami ◽  
Dispersion Effect ◽  
The Indian Ocean ◽  
Process Dispersion ◽  
Runup Height

We conducted a numerical simulation that takes into account the effect of wave frequency dispersion in the Indian Ocean Tsunami that occurred on December 26, 2004. A leapfrog-implicit numerical scheme based on Shigihara et al. [6] is applicable to practical simulation. Dispersion effect is negligible for the runup to the northwest coast of Sumatra Island. At the west side of tsunami source, if the aim of simulation is the reproduction of detailed propagation process, dispersion should be considered in Sri Lanka. If maximum runup height and tsunami arrival time are required, however, dispersion may be negligible.

scholarly journals SwissFEL Aramis beamline photon diagnostics

2018 ◽  
Vol 25 (4) ◽  
pp. 1238-1248 ◽  
Author(s):  
Pavle Juranić ◽  
Jens Rehanek ◽  
Christopher A. Arrell ◽  
Claude Pradervand ◽  
Rasmus Ischebeck ◽  
...  
Keyword(s):  
Arrival Time ◽  
Pulse Length ◽  
Beam Shape ◽  
Time Jitter ◽  
New Developments ◽  
X Ray ◽  
Photon Pulse ◽  
Flux Spectrum ◽  
Shape And Size

The SwissFEL Aramis beamline, covering the photon energies between 1.77 keV and 12.7 keV, features a suite of online photon diagnostics tools to help both users and FEL operators in analysing data and optimizing experimental and beamline performance. Scientists will be able to obtain information about the flux, spectrum, position, pulse length, and arrival time jitterversusthe experimental laser for every photon pulse, with further information about beam shape and size available through the use of destructive screens. This manuscript is an overview of the diagnostics tools available at SwissFEL and presents their design, working principles and capabilities. It also features new developments like the first implementation of a THz-streaking based temporal diagnostics for a hard X-ray FEL, capable of measuring pulse lengths to 5 fs r.m.s. or better.

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