Comparison of NGA-West2 Directivity Models

2014 ◽  
Vol 30 (3) ◽  
pp. 1199-1221 ◽  
Author(s):  
Paul Spudich ◽  
Badie Rowshandel ◽  
Shrey K. Shahi ◽  
Jack W. Baker ◽  
Brian S.-J. Chiou
Keyword(s):  
Numerical Simulations ◽  
Narrow Band ◽  
Scale Up ◽  
Strike Slip ◽  
Earthquake Magnitude ◽  
Zero Level ◽  
Geographic Distributions

Five directivity models have been developed based on data from the NGA-West2 database and based on numerical simulations of large strike-slip and reverse-slip earthquakes. All models avoid the use of normalized rupture dimension, enabling them to scale up to the largest earthquakes in a physically reasonable way. Four of the five models are explicitly “narrow-band” (in which the effect of directivity is maximum at a specific period that is a function of earthquake magnitude). Several strategies for determining the zero-level for directivity have been developed. We show comparisons of maps of the directivity amplification. This comparison suggests that the predicted geographic distributions of directivity amplification are dominated by effects of the models’ assumptions, and more than one model should be used for ruptures dipping less than about 65 degrees.

Off-fault Deformation Associated with Strike-slip Faults

2018 ◽  
Vol 24 (4) ◽  
pp. 375-384
Author(s):  
Jeffrey A. Johnson
Keyword(s):  
Slip Surface ◽  
Strike Slip ◽  
Earthquake Magnitude ◽  
Slip Zone ◽  
Fault Rupture ◽  
Fault Deformation ◽  
Simplified Procedure ◽  
Inelastic Strains ◽  
Adequate Design ◽  
Cultural Features

Abstract Habitable buildings can be protected from surface fault rupture by establishing structure “setback zones” similar in purpose to legally mandated zones in California and Utah. But post-earthquake surveys of offset and warped linear cultural features, believed to have been straight prior to the event, demonstrate that potentially damaging inelastic strains or off-fault deformation can extend tens of meters beyond the principal slip zone of strike-slip surface fault ruptures. Setback zones designed to also mitigate off-fault deformation are likely to be prohibitively wide, indicating the need for structural and geotechnical engineering solutions to accommodate the potentially damaging strains within adequate design buffers. This study analyzes nine strike-slip surface fault ruptures between 1906 and 2014 and develops a simplified procedure to quantify off-fault deformation based on earthquake magnitude and distance from the principal slip zone of strike-slip faults.

scholarly journals Investigating the Deformation and Failure Mechanism of a Submarine Tunnel with Flexible Joints Subjected to Strike-Slip Faults

2021 ◽  
Vol 9 (12) ◽  
pp. 1412
Author(s):  
Guangxin Zhou ◽  
Qian Sheng ◽  
Zhen Cui ◽  
Tianqiang Wang ◽  
Yalina Ma
Keyword(s):  
Numerical Simulations ◽  
Fault Zone ◽  
Cross Section ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Design Parameters ◽  
Flexible Joints ◽  
Flexible Joint ◽  
Deformation And Failure ◽  
Tunnel Cross Section

Knowledge from historical earthquake events indicates that a submarine tunnel crossing active strike-slip faults is prone to be damaged in an earthquake. Previous studies have demonstrated that the flexible joints are an effective measure for a submarine tunnel crossing a strike-slip fault. The background project of this paper is the second submarine tunnel of Jiaozhou bay. In this work, model tests and numerical simulations are conducted to investigate the deformation and failure mechanism of a submarine tunnel with flexible joints under a strike-slip fault dislocation. The influence of strike-slip faults on a tunnel with flexible joints has been investigated by examining the deformation of rock mass surface, analyzing lining stains, and crack propagation from model tests. Numerical simulations are conducted to study the effects of the design parameters of a tunnel with flexible joints on the mechanical response of the lining. The results showed that the ‘articulated design’ measure can improve the ability of the tunnel to resist the strike-slip faults. In terms of the mechanism of design parameters of a tunnel with flexible joints, this paper finds that increasing the lining thickness, decreasing the lining segment length, and decreasing the tunnel diameter to a reasonable extent could effectively improve the performance of this faulting resistance measure for a tunnel under the strike-slip fault zone dislocation. Compared with the horseshoe tunnel cross-section, the circular tunnel cross-section can improve the ability of the faulting resistance of a tunnel with flexible joints, while the optimal angle of the tunnel crossing the fault zone is 90º. It is concluded that the wider fault zone, smaller flexible joint width, and less stiffness of the flexible joint could make lining safer under a strike-slip fault dislocation. The above research results can serve as a necessary theoretical reference and technical support for the design of reinforcement measures for a submarine tunnel with flexible joints under strike-slip fault dislocation.

SPIRAL WAVE MAINTAINED BY NOISE

2004 ◽  
Vol 04 (03) ◽  
pp. L447-452 ◽  
Author(s):  
AI ZHONG LEI ◽  
QIAN SHU LI ◽  
WEIGUO XU ◽  
DAIPING HU
Keyword(s):  
White Noise ◽  
Numerical Simulations ◽  
Noise Level ◽  
Gaussian White Noise ◽  
Spiral Wave ◽  
Reaction Diffusion ◽  
Spiral Waves ◽  
Reaction Diffusion System ◽  
Diffusion System ◽  
Zero Level

The effect of Gaussian white noise on a chemical wavefront is studied in a modified FitzHugn–Nagumo model by applying numerical simulations. A rotating spiral waves can be formed if the medium is excitable enough and the fronts has a free end, when the reaction diffusion system is disturbed by a certain non-zero level noise. It is counterintuitive that noise plays a constructive role in the product and propagation of single spiral waves in this letter. Weak or strong noise will make against the product and propagation of spiral waves. In a certain noise level, spiral wave can be maintained in a medium, where such spiral waves cannot be observed in the absence of the noise.

scholarly journals Numerical Simulations on Polarization Quantum Noise Squeezing for Ultrashort Solitons in Optical Fiber with Enlarged Mode Field Area

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 226
Author(s):  
Arseny A. Sorokin ◽  
Elena A. Anashkina ◽  
Joel F. Corney ◽  
Vjaceslavs Bobrovs ◽  
Gerd Leuchs ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Numerical Simulations ◽  
Noise Suppression ◽  
Quantum Noise ◽  
Scale Up ◽  
Optical Pulses ◽  
Mode Field ◽  
Mode Area ◽  
Noise Squeezing ◽  
Field Area

Broadband quantum noise suppression of light is required for many applications, including detection of gravitational waves, quantum sensing, and quantum communication. Here, using numerical simulations, we investigate the possibility of polarization squeezing of ultrashort soliton pulses in an optical fiber with an enlarged mode field area, such as large-mode area or multicore fibers (to scale up the pulse energy). Our model includes the second-order dispersion, Kerr and Raman effects, quantum noise, and optical losses. In simulations, we switch on and switch off Raman effects and losses to find their contribution to squeezing of optical pulses with different durations (0.1–1 ps). For longer solitons, the peak power is lower and a longer fiber is required to attain the same squeezing as for shorter solitons, when Raman effects and losses are neglected. In the full model, we demonstrate optimal pulse duration (~0.4 ps) since losses limit squeezing of longer pulses and Raman effects limit squeezing of shorter pulses.

Roll of a Ship in Astern Seas—Response to GM Fluctuations

1989 ◽  
Vol 33 (04) ◽  
pp. 284-290
Author(s):  
A. Bruce Dunwoody
Keyword(s):  
Numerical Simulations ◽  
Narrow Band ◽  
Wide Band ◽  
Random Processes ◽  
Roll Motion ◽  
Roll Damping ◽  
Metacentric Height ◽  
Good Agreement

An effect of astern seas on a ship is to produce fluctuations in the metacentric height (GM) of the ship. GM fluctuations are shown to produce an effect analogous to a reduction in the roll damping. Roll damping reductions are predicted for two extreme types of random GM fluctuations: wide-band and narrow-band random processes. Numerical simulations of the roll motion of a ship with realistic random GM fluctuations are used to compare with the predictions of damping reduction. Good agreement is found. Implications of a reduced roll damping are discussed.

scholarly journals New Mass-Conserving Algorithm for Level Set Redistancing on Unstructured Meshes

2006 ◽  
Vol 73 (6) ◽  
pp. 1011-1016 ◽  
Author(s):  
Fernando Mut ◽  
Gustavo C. Buscaglia ◽  
Enzo A. Dari
Keyword(s):  
Level Set ◽  
Narrow Band ◽  
Unstructured Meshes ◽  
Initial Shape ◽  
Zero Level ◽  
Level Set Function ◽  
Mass Correction ◽  
Computing Effort ◽  
Correction Step ◽  
Set Function

The level set method is becoming increasingly popular for the simulation of several problems that involve interfaces. The level set function is advected by some velocity field, with the zero-level set of the function defining the position of the interface. The advection distorts the initial shape of the level set function, which needs to be re-initialized to a smooth function preserving the position of the zero-level set. Many algorithms re-initialize the level set function to (some approximation of) the signed distance from the interface. Efficient algorithms for level set redistancing on Cartesian meshes have become available over the last years, but unstructured meshes have received little attention. This presentation concerns algorithms for construction of a distance function from the zero-level set, in such a way that mass is conserved on arbitrary unstructured meshes. The algorithm is consistent with the hyperbolic character of the distance equation (‖∇d‖=1) and can be localized on a narrow band close to the interface, saving computing effort. The mass-correction step is weighted according to local mass differences, an improvement over usual global rebalancing techniques.

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