Estimating Time Scales and Length Scales in Pulselike Earthquake Acceleration Records with Wavelet Analysis

2011 ◽  
Vol 101 (2) ◽  
pp. 596-618 ◽  
Author(s):  
M. F. Vassiliou ◽  
N. Makris
Keyword(s):  
Wavelet Analysis ◽  
Time Scales ◽  
Length Scales

scholarly journals Scale-Selective Precision for Weather and Climate Forecasting

2019 ◽  
Vol 147 (2) ◽  
pp. 645-655 ◽  
Author(s):  
Matthew Chantry ◽  
Tobias Thornes ◽  
Tim Palmer ◽  
Peter Düben
Keyword(s):  
Time Scales ◽  
Weather Forecasting ◽  
Forecast Accuracy ◽  
Spectral Space ◽  
Dynamical Equations ◽  
Length Scales ◽  
Climate Forecasting ◽  
Spectral Models ◽  
Weather And Climate ◽  
Numerical Precision

Abstract Attempts to include the vast range of length scales and physical processes at play in Earth’s atmosphere push weather and climate forecasters to build and more efficiently utilize some of the most powerful computers in the world. One possible avenue for increased efficiency is in using less precise numerical representations of numbers. If computing resources saved can be reinvested in other ways (e.g., increased resolution or ensemble size) a reduction in precision can lead to an increase in forecast accuracy. Here we examine reduced numerical precision in the context of ECMWF’s Open Integrated Forecast System (OpenIFS) model. We posit that less numerical precision is required when solving the dynamical equations for shorter length scales while retaining accuracy of the simulation. Transformations into spectral space, as found in spectral models such as OpenIFS, enact a length scale decomposition of the prognostic fields. Utilizing this, we introduce a reduced-precision emulator into the spectral space calculations and optimize the precision necessary to achieve forecasts comparable with double and single precision. On weather forecasting time scales, larger length scales require higher numerical precision than smaller length scales. On decadal time scales, half precision is still sufficient precision for everything except the global mean quantities.

Hydration Dynamics at Femtosecond Time Scales and Angstrom Length Scales from Inelastic X-Ray Scattering

2009 ◽  
Vol 103 (23) ◽  
Author(s):  
Robert H. Coridan ◽  
Nathan W. Schmidt ◽  
Ghee Hwee Lai ◽  
Rahul Godawat ◽  
Michael Krisch ◽  
...  
Keyword(s):  
Time Scales ◽  
Length Scales ◽  
X Ray ◽  
X Ray Scattering ◽  
Hydration Dynamics ◽  
Ray Scattering

scholarly journals ONSET OF SHEAR WAVES IN A BACTERIAL BATH: A NOVEL EFFECT

2003 ◽  
Vol 03 (04) ◽  
pp. L373-L377 ◽  
Author(s):  
SUPURNA SINHA
Keyword(s):  
Time Scales ◽  
Shear Waves ◽  
Particle Diffusion ◽  
Length Scales ◽  
Structural Ordering ◽  
Propagating Shear

Recent experiments on particle diffusion in bacterial baths indicate the formation of correlated structures in the form of bacterial swirls. Here we predict that such a structural ordering would give rise to the new effect of propagating shear waves in a bacterial bath at length scales of the order of a swirl, which corresponds to time scales of the order of the lifetime of a swirl. Our prediction can be tested against future experiments in bacterial baths.

Identification of the principal time scales in bubble column by wavelet analysis

2001 ◽  
Vol 56 (20) ◽  
pp. 5739-5747 ◽  
Author(s):  
A.A. Kulkarni ◽  
J.B. Joshi ◽  
V. Ravi Kumar ◽  
B.D. Kulkarni
Keyword(s):  
Wavelet Analysis ◽  
Time Scales ◽  
Bubble Column

Numerical modeling of multiple length scales in thermal transport processes

2014 ◽  
Vol 24 (4) ◽  
pp. 781-796 ◽  
Author(s):  
Yogesh Jaluria
Keyword(s):  
Numerical Modeling ◽  
Boundary Conditions ◽  
Time Scales ◽  
Transport Processes ◽  
Thermal Processes ◽  
Length Scales ◽  
Content Type ◽  
Multiple Length Scales ◽  
Wide Range ◽  
Simulation Results

Purpose – Multiple length and time scales arise in a wide variety of practical and fundamental problems. It is important to obtain accurate and validated numerical simulation results, considering the different scales that exist, in order to predict, design and optimize the behavior of practical thermal processes and systems. The purpose of this paper is to present modeling at the different length scales and then addresses the question of coupling the different models to obtain the overall model for the system or process. Design/methodology/approach – Both numerical and experimental methods to obtain results at the different length scales, particularly at micro and nanoscales, are considered. Even though the paper focusses on length scales, multiple time scales lead to similar concerns and are also considered. The two circumstances considered in detail are multiple length scales in different domains and those in the same domain. These two cases have to be modeled quite differently in order to obtain a model for the overall process or system. The basic considerations involved in such a modeling are discussed. A wide range of thermal processes are considered and the methods that may be used are presented. The models employed must be validated and the accuracy of the simulation results established if the simulation results are to be used for prediction, control and design. Findings – Of particular interest are concerns like verification and validation, imposition of appropriate boundary conditions, and modeling of complex, multimode transport phenomena in multiple scales. Additional effects such as viscous dissipation, surface tension, buoyancy and rarefaction that could arise and complicate the modeling are discussed. Uncertainties that arise in material properties and in boundary conditions are also important in design and optimization. Large variations in the geometry and coupled multiple regions are also discussed. Research limitations/implications – The paper is largely focussed on multiple-scale considerations in thermal processes. Both numerical modeling/simulation and experimentation are considered, with the latter being used for validation and physical insight. Practical implications – Several examples from materials processing, environmental flows and electronic systems, including data centers, are given to present the different techniques that may be used to achieve the desired level of accuracy and predictability. Originality/value – Present state of the art and future needs in this interesting and challenging area are discussed, providing the impetus for further work. Different methods for treating multiscale problems are presented.

scholarly journals The nature and origin of the Barrovian metamorphism, Scotland: diffusion length scales in garnet and inferred thermal time scales

2011 ◽  
Vol 168 (1) ◽  
pp. 115-132 ◽  
Author(s):  
Daniel R. Viete ◽  
Jörg Hermann ◽  
Gordon S. Lister ◽  
Iona R. Stenhouse
Keyword(s):  
Time Scales ◽  
Diffusion Length ◽  
Thermal Time ◽  
Length Scales

scholarly journals Variability in net ecosystem exchange from hourly to inter-annual time scales at adjacent pine and hardwood forests: a wavelet analysis

2005 ◽  
Vol 25 (7) ◽  
pp. 887-902 ◽  
Author(s):  
P. C. Stoy ◽  
G. G. Katul ◽  
M. B. S. Siqueira ◽  
J.-Y. Juang ◽  
H. R. McCarthy ◽  
...  
Keyword(s):  
Wavelet Analysis ◽  
Time Scales ◽  
Net Ecosystem Exchange ◽  
Hardwood Forests ◽  
Annual Time

scholarly journals Wavelet analysis for seasonal precipitation variations of Yuanmou dry-hot valley in recent 50 years

MAUSAM ◽  
2021 ◽  
Vol 68 (4) ◽  
pp. 663-672
Author(s):  
L. N. SUN ◽  
J. Y. WANG ◽  
B. ZHANG
Keyword(s):  
Wavelet Analysis ◽  
Time Scales ◽  
Periodic Oscillation ◽  
Landscape Patterns ◽  
Annual Precipitation ◽  
Seasonal Precipitation ◽  
Short Term ◽  
Time Frequency ◽  
Precipitation Variation ◽  
Meyer Wavelet

The dry-hot valley is a special kind of degradation ecosystem region in Hengduan Mountains. Variations of seasonal precipitation have important influnces on its landscape patterns and agricultural activities. Based on the monthly and annual precipitation data from 1956 to 2006, the multi-time scales characteristics of seasonal and annual variations of precipitation in the past 50a in the Yuanmou County had been analyzed using Meyer wavelet analysis in this paper. The periodic oscillation of precipitation variation and the points of abrupt change at different time scales along the time series are discovered and the main periods of every serial are confirmed. It was showed that the periodic oscillation of 8-12a and 4-6a for the seasonal and annual precipitation variation are obvious. The time-frequency local change characteristic of Meyer wavelet analysis can demonstrate the fine structures of precipitation and the method provides a new way in analyzing climate multi-time scales characteristics and forecasting short-term climate. The localization characteristics of time -frequency for wavelet analysis can demonstrate the detailed structures of rainfall. The wavelet analysis can be an alternative approach to analyze climate multi-time scales characteristics and forecast short-term climate variations. The research on the regularity of seasonal precipitation variation in the dry-hot valley region has a great guidance meaning to the agriculture production and resilience in flood prevention.  

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