scholarly journals Consistency between Fourier transform and small-volume few-wave decomposition for spectral and spatial variability of gravity waves above a typhoon

2012 ◽  
Vol 5 (1) ◽  
pp. 1763-1793
Author(s):  
C. I. Lehmann ◽  
Y.-H. Kim ◽  
P. Preusse ◽  
H.-Y. Chun ◽  
M. Ern ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Momentum Flux ◽  
Wide Spectrum ◽  
Three Dimensional ◽  
Phase Speed ◽  
Analysis Technique ◽  
Momentum Fluxes ◽  
Different Types ◽  
Wave Decomposition ◽  
First Time

Abstract. Convective gravity wave (GW) sources are spatially localized and emit at the same time waves with a wide spectrum of phase speeds. Any wave analysis therefore compromises between spectral and spatial resolution. Future satellite borne limb imagers will for a first time provide real 3d volumes of observations. These volumes will be however limited which will impose further constraints on the analysis technique. In this study a three dimensional few-wave appoach fitting sinusoidal waves to limited 3-D volumes is introduced. The method is applied to simulated GWs above typhoon Ewiniar and GW momentum flux is estimated from temperature fluctuations. Phase speed spectra as well as average profiles of positive, negative and net momentum fluxes are compared to momentum flux estimated by Fourier transform as well as spatial averaging of wind fluctuations. The results agree within 10–20%. The few-wave method can also reveal the spatial orientation of the GWs with respect to the source. The relevance of the results for different types of measurements as well as its applicability to model data is discussed.

scholarly journals Consistency between Fourier transform and small-volume few-wave decomposition for spectral and spatial variability of gravity waves above a typhoon

2012 ◽  
Vol 5 (7) ◽  
pp. 1637-1651 ◽  
Author(s):  
C. I. Lehmann ◽  
Y.-H. Kim ◽  
P. Preusse ◽  
H.-Y. Chun ◽  
M. Ern ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Momentum Flux ◽  
Wide Spectrum ◽  
Three Dimensional ◽  
Phase Speed ◽  
Analysis Technique ◽  
Momentum Fluxes ◽  
Different Types ◽  
Wave Decomposition ◽  
First Time

Abstract. Convective gravity wave (GW) sources are spatially localized and emit at the same time waves with a wide spectrum of phase speeds. Any wave analysis therefore compromises between spectral and spatial resolution. Future satellite borne limb imagers will for a first time provide real 3-D volumes of observations. These volumes will be however limited which will impose further constraints on the analysis technique. In this study a three dimensional few-wave approach fitting sinusoidal waves to limited 3-D volumes is introduced. The method is applied to simulated GWs above typhoon Ewiniar and GW momentum flux is estimated from temperature fluctuations. Phase speed spectra as well as average profiles of positive, negative and net momentum fluxes are compared to momentum flux estimated by Fourier transform as well as spatial averaging of wind fluctuations. The results agree within 10–20%. The few-wave method can also reveal the spatial orientation of the GWs with respect to the source. The relevance of the results for different types of measurements as well as its applicability to model data is discussed.

scholarly journals Gravity wave amplitudes and momentum fluxes inferred from OH airglow intensities and meteor radar winds during SpreadFEx

2009 ◽  
Vol 27 (6) ◽  
pp. 2361-2369 ◽  
Author(s):  
F. Vargas ◽  
D. Gobbi ◽  
H. Takahashi ◽  
L. M. Lima
Keyword(s):  
Gravity Waves ◽  
Horizontal Wind ◽  
Small Scale ◽  
Meteor Radar ◽  
Plasma Bubble ◽  
Spatial And Temporal Scales ◽  
Analysis Technique ◽  
Momentum Fluxes ◽  
Different Types ◽  
Wave Directionality

Abstract. We show in this report the momentum flux content input in the mesosphere due to relatively fast and small scale gravity waves (GWs) observed through OH airglow images. The acquisition of OH NIR images was carried out in Brazil at Brasilia (14.8° S, 47.6° W) and Cariri (7.4° S, 36.5° W) from September 2005 to November 2005 during the SpreadFEx Campaign. Horizontal wind information from meteor radar was available in Cariri only. Our findings showed strong wave activity in both sites, mainly in Cariri. High wave directionality was also observed in both sites during SpreadFEx, which have been observed by other investigators using different analysis' techniques and different types of data during the campaign. We discuss also the possibility of plasma bubble seeding by gravity waves presenting spatial and temporal scales estimated with our novel analysis technique during the SpreadFEx campaign.

Numerical Simulation of Ultrasonic-Assisted Grinding Surfaces With Fast Fourier Transform

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Lin Li ◽  
Jinyuan Tang ◽  
Yuqin Wen ◽  
Caichao Zhu
Keyword(s):  
Numerical Simulation ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Autocorrelation Function ◽  
Three Dimensional ◽  
Simulation Models ◽  
Research Focus ◽  
Ultrasonic Assisted Grinding ◽  
Ultrasonic Assisted ◽  
First Time

Abstract Numerical simulation of three-dimensional rough surfaces based on fast Fourier transform (FFT) is revisited. A more systematic approach, which is an extension of the current FFT-based simulation models, is proposed to approach surface reconstruction. Moreover, the simulation of the surfaces with machining signature by prescribing the parameters, take ultrasonic-assisted grinding as an example, has been taken as the research focus for the first time. The effectiveness is tested by three cases of simulation examples. Excepting the surface with exponential autocorrelation function, the simulation of surfaces with grinding machining marks is considered both by prescribing the theory autocorrelation function and by measuring a small area as a sample. The results show that the proposed method has great potential in engineering applications.

Momentum Fluxes of Gravity Waves Generated by Variable Froude Number Flow over Three-Dimensional Obstacles

2010 ◽  
Vol 67 (7) ◽  
pp. 2260-2278 ◽  
Author(s):  
Stephen D. Eckermann ◽  
John Lindeman ◽  
Dave Broutman ◽  
Jun Ma ◽  
Zafer Boybeyi
Keyword(s):  
Froude Number ◽  
Gravity Waves ◽  
Momentum Flux ◽  
Mesoscale Model ◽  
Three Dimensional ◽  
Wave Drag ◽  
Analytical Relation ◽  
Far Field ◽  
Pressure Drag ◽  
Momentum Fluxes

Abstract Fully nonlinear mesoscale model simulations are used to investigate the momentum fluxes of gravity waves that emerge at a “far-field” height of 6 km from steady unsheared flow over both an axisymmetric and elliptical obstacle for nondimensional mountain heights ĥm = Fr−1 in the range 0.1–5, where Fr is the surface Froude number. Fourier- and Hilbert-transform diagnostics of model output yield local estimates of phase-averaged momentum flux, while area integrals of momentum flux quantify the amount of surface pressure drag that translates into far-field gravity waves, referred to here as the “wave drag” component. Estimates of surface and wave drag are compared to parameterization predictions and theory. Surface dynamics transition from linear to high-drag (wave breaking) states at critical inverse Froude numbers Frc−1 predicted to within 10% by transform relations. Wave drag peaks at Frc−1 < ĥm ≲ 2, where for the elliptical obstacle both surface and wave drag vacillate owing to cyclical buildup and breakdown of waves. For the axisymmetric obstacle, this occurs only at ĥm = 1.2. At ĥm ≳ 2–3 vacillation abates and normalized pressure drag assumes a common normalized form for both obstacles that varies approximately as ĥm−1.3. Wave drag in this range asymptotes to a constant absolute value that, despite its theoretical shortcomings, is predicted to within 10%–40% by an analytical relation based on linear clipped-obstacle drag for a Sheppard-based prediction of dividing streamline height. Constant wave drag at ĥm ∼ 2–5 arises despite large variations with ĥm in the three-dimensional morphology of the local wave momentum fluxes. Specific implications of these results for the parameterization of subgrid-scale orographic drag in global climate and weather models are discussed.

scholarly journals Momentum Flux Spectrum of Convective Gravity Waves. Part I: An Update of a Parameterization Using Mesoscale Simulations

2011 ◽  
Vol 68 (4) ◽  
pp. 739-759 ◽  
Author(s):  
Hyun-Joo Choi ◽  
Hye-Yeong Chun
Keyword(s):  
Wave Propagation ◽  
Numerical Simulations ◽  
Momentum Flux ◽  
Three Dimensional ◽  
Phase Speed ◽  
Wave Drag ◽  
Spectral Space ◽  
Source Spectrum ◽  
Flux Spectrum ◽  
Moving Speed

Abstract The convective source and momentum flux spectra of a parameterization of convective gravity wave drag (GWDC) are validated in a three-dimensional spectral space using mesoscale numerical simulations for various ideal and real convective storms. From this, two important free parameters included in the GWDC parameterization—the moving speed of the convective source and the wave propagation direction—are determined. In the numerical simulations, the convective source spectrum shows nearly isotropic features in terms of magnitude, and its primary peak in any azimuthal direction occurs at a phase speed that equals the moving speed of the convective source in the same direction. It is found that the moving speed of the convective source is closely correlated with the basic-state wind averaged below 700 hPa (u700 and υ700). When the analytic convective source spectrum of the parameterization is calculated using the moving speed of the convective source as determined by u700 and υ700, its shape in all storm cases agrees with that from the simulation. The momentum flux spectrum at launch level (cloud top) is also calculated using the basic-state conditions and the moving speed of the convective source as determined by u700 and υ700. A comparison between the parameterization and simulation results shows that the parameterization reproduces the momentum flux spectrum from the simulation reasonably well. In the parameterization, two wave propagation directions of 45° (northeast and southwest) and 135° (northwest and southeast) best represent the momentum flux spectra from the simulations integrated over all directions when the minimum number of wave propagation directions is required for computational efficiency.

The Zona Pellucida Porosity: Three-Dimensional Reconstruction of Four Types of Mouse Oocyte Zona Pellucida Using a Dual Beam Microscope

2012 ◽  
Vol 18 (6) ◽  
pp. 1442-1449 ◽  
Author(s):  
Sergi Novo ◽  
Leonardo Barrios ◽  
Elena Ibáñez ◽  
Carme Nogués
Keyword(s):  
3D Reconstruction ◽  
Zona Pellucida ◽  
Ion Beam ◽  
Three Dimensional ◽  
Mouse Oocyte ◽  
Dual Beam ◽  
Different Types ◽  
Dimensional Reconstruction ◽  
Focus Ion Beam ◽  
First Time

AbstractIn the last decade, the applicability of focus ion beam–field emission scanning electron microscopy (FIB-FESEM) in the biological field has begun to get relevance. Among the possibilities offered by FIB-FESEM, high-resolution three-dimensional (3D) reconstruction of biological structures is one of the most interesting. Using this tool, the 3D porosity of four different types of mouse oocyte zona pellucida (ZP) was analyzed. A surface analysis of the mouse oocyte ZP was first performed by SEM. Next, one oocyte per ZP type was selected, and an area of its ZP was completely milled, using the cut and view mode, in the FIB-FESEM. Through a 3D reconstruction of the milled area, a map of the distribution of the pores across the ZP was established and the number and volume of pores were quantified, thus enabling for the first time the study of the inner porosity of the mouse ZP. Differences in ZP porosity observed among the four types analyzed allowed us to outline a model to explain the changes that the ZP undergoes through immature, mature, predegenerative, and degenerative stages.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

A Study on Utilization of Three-Dimensional Sensor Lip Image for Developing a Pronunciation Recognition System

2019 ◽  
Vol 63 (5) ◽  
pp. 50402-1-50402-9 ◽  
Author(s):  
Ing-Jr Ding ◽  
Chong-Min Ruan
Keyword(s):  
Principal Component Analysis ◽  
Automatic Speech Recognition ◽  
Feature Fusion ◽  
Three Dimensional ◽  
Principal Component ◽  
Recognition System ◽  
Geometrical Characteristics ◽  
3D Geometry ◽  
Different Types ◽  
The Disabled

Abstract The acoustic-based automatic speech recognition (ASR) technique has been a matured technique and widely seen to be used in numerous applications. However, acoustic-based ASR will not maintain a standard performance for the disabled group with an abnormal face, that is atypical eye or mouth geometrical characteristics. For governing this problem, this article develops a three-dimensional (3D) sensor lip image based pronunciation recognition system where the 3D sensor is efficiently used to acquire the action variations of the lip shapes of the pronunciation action from a speaker. In this work, two different types of 3D lip features for pronunciation recognition are presented, 3D-(x, y, z) coordinate lip feature and 3D geometry lip feature parameters. For the 3D-(x, y, z) coordinate lip feature design, 18 location points, each of which has 3D-sized coordinates, around the outer and inner lips are properly defined. In the design of 3D geometry lip features, eight types of features considering the geometrical space characteristics of the inner lip are developed. In addition, feature fusion to combine both 3D-(x, y, z) coordinate and 3D geometry lip features is further considered. The presented 3D sensor lip image based feature evaluated the performance and effectiveness using the principal component analysis based classification calculation approach. Experimental results on pronunciation recognition of two different datasets, Mandarin syllables and Mandarin phrases, demonstrate the competitive performance of the presented 3D sensor lip image based pronunciation recognition system.

ANALYSIS OF AUTOMATIC TRANSMISSION USING FOURIER TRANSFORM INFRARED (FTIR) SPECTROCOPY

2019 ◽  
Vol 7 (SI-TeMIC18) ◽  
Author(s):  
Norhanifah Abdul Rahman ◽  
Matzaini Katon Katon ◽  
Nurina Alya Zulkifli Zulkifli
Keyword(s):  
Fourier Transform ◽  
Automatic Transmission ◽  
Fourier Transform Infrared ◽  
Oil Analysis ◽  
Wear Particles ◽  
Reliable Technique ◽  
Fluid Analysis ◽  
Analysis Technique ◽  
Machine Elements ◽  
Transmission Fluid

Automatic Transmission (AT) system is efficient in the aspects of vehicle safety, comfort, reliability and driving performance. The objectives of this paper are to collect the oil samples from AT systems of engine bus according to manufacturer's recommendations and analyse collected oil samples using oil analysis technique. The sample transmission fluid which was taken from the AT gearbox has been experimentally analyzed. The oil samples were taken with an interval of 5,000km, 30,000km, 50,000km, 80,000km, 180,000km and 300,000km for AT bus operation. These samples then have been analyzed by comparing between new and used transmission fluid using Fourier Transform Infrared (FTIR) spectroscopy. Oil analysis by FTIR is a form of Predictive Maintenance (PdM) to avoid major failure in machine elements. Most machine elements are not easily accessible in the transmission system. Having a reliable technique would avoid the needs to open the components unnecessarily, hence, help to prevent catastrophic failure which are very costly, and ease of regular monitoring. In order to identify the major failures of automatic gearbox, forecasts can be made regarding the lube transmission fluid analysis test. By using this test, the minor problems can be determined before they become major failures. At the end of this research, the wear particles profile for interval mileage of AT system was obtained. Keywords: Wear, Automatic Transmission (AT), Transmission fluid, Fourier Transform Infrared (FTIR), Oil analysis.

Simulating Self-Regeneration and Self-Replication Processes Using Movable Cellular Automata with a Mutual Equilibrium Neighborhood

2020 ◽  
Vol 29 (4) ◽  
pp. 741-757
Author(s):  
Kateryna Hazdiuk ◽  
◽  
Volodymyr Zhikharevich ◽  
Serhiy Ostapov ◽  
◽  
...  
Keyword(s):  
Cellular Automata ◽  
Cellular Automaton ◽  
Three Dimensional ◽  
Computer Models ◽  
The Self ◽  
Model Construction ◽  
Natural Phenomena ◽  
Different Types ◽  
Movable Cellular Automata ◽  
Self Replication

This paper deals with the issue of model construction of the self-regeneration and self-replication processes using movable cellular automata (MCAs). The rules of cellular automaton (CA) interactions are found according to the concept of equilibrium neighborhood. The method is implemented by establishing these rules between different types of cellular automata (CAs). Several models for two- and three-dimensional cases are described, which depict both stable and unstable structures. As a result, computer models imitating such natural phenomena as self-replication and self-regeneration are obtained and graphically presented.

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