Wavelet spectrum estimation

Geophysics ◽  
1999 ◽  
Vol 64 (6) ◽  
pp. 1836-1846 ◽  
Author(s):  
Tik Hing Tan
Keyword(s):  
Material Properties ◽  
Pressure Field ◽  
Wavelet Spectrum ◽  
Measured Data ◽  
Complex Spectrum ◽  
Spectrum Estimation ◽  
Wave Propagation Velocity ◽  
Complex Source ◽  
Individual Source ◽  
Source Array

A method for complex source signature estimation for offshore acquisition is presented. Although the wave‐propagation velocity in the water is assumed to be known, no assumptions about the material properties underwater are made. The inputs to the algorithm are the pressure field measured along an end of spread streamer cable, the coordinates of the sources, and the depth of the cable. The output is the complex spectrum of each individual source in the source array. This article discusses the physical interpretation of the equations. It is shown that the estimated wavelets depend on the direct field only. The sensitivities of the method are also discussed. Application of the algorithm on generated and measured data is presented.

Bend Allowance and Developed Length Calculation for Pressbrake Bending

1997 ◽  
Vol 119 (2) ◽  
pp. 227-237 ◽  
Author(s):  
F. Pourboghrat ◽  
K. A. Stelson
Keyword(s):  
Strain Hardening ◽  
Sheet Metal ◽  
Material Properties ◽  
Empirical Equation ◽  
Measured Data ◽  
Neutral Axis ◽  
Physically Based

Developed length refers to the length of the unstretched fiber measured over both bent and straight sections of a bent sheet. Bend allowance is a term coined by Sachs as a measure of the length of the unstretched fiber in the bent section. Sachs’ empirical equation for calculating bend allowance is not physically based and is independent of material and forming conditions. A physics-based model for calculating bend allowance and developed length for a strain hardening sheet metal formed by pressbrake bending is presented. Effects of material properties and tooling geometry on the calculation of these parameters are considered. It is shown that unlike Sachs’ assumption, it is the deformed shape and not the neutral axis shift or thinning that is important for calculating the developed length in pressbrake bending. It is also shown, by comparing calculated and measured data, that better accuracy can be obtained when the proposed method is used instead of Sachs’ empirical equation.

A Data-Constrained 3D Model for Material Compositional Microstructures

2008 ◽  
Vol 32 ◽  
pp. 267-270 ◽  
Author(s):  
Sam Yang ◽  
Scott Furman ◽  
Andrew Tulloh
Keyword(s):  
Mathematical Model ◽  
Material Properties ◽  
Reasonable Agreement ◽  
3D Model ◽  
Compositional Data ◽  
Simulated Data ◽  
Measured Data ◽  
Porosity Distribution ◽  
Numerical Predictions ◽  
Tomography Data

A mathematical model has been developed for predicting material compositional microstructures using measured data as constraints. Examples of measured data include 3-D sets of tomography data, 2-D sets of compositional data on surfaces and sections, and material absorption and interaction properties. The model has been partially implemented as a MS-Windows application. Reasonable agreement has been obtained between the numerical predictions from the software and the simulated data. The predicted microstructures could be used to study various material properties such as porosity distribution, diffusion and corrosion.

Efficient Uncertainty Quantification for Biotransport in Tumors With Uncertain Material Properties

2018 ◽  
Author(s):  
Alen Alexanderian ◽  
William Reese ◽  
Ralph C. Smith ◽  
Meilin Yu
Keyword(s):  
Porous Media ◽  
Random Field ◽  
Material Properties ◽  
Pressure Field ◽  
Input Parameter ◽  
Gaussian Random Field ◽  
Porous Media Flow ◽  
Expansion Technique ◽  
Low Dimensional ◽  
Permeability Field

We consider modeling of single phase fluid flow in heterogeneous porous media governed by elliptic partial differential equations (PDEs) with random field coefficients. Our target application is biotransport in tumors with uncertain heterogeneous material properties. We numerically explore dimension reduction of the input parameter and model output. In the present work, the permeability field is modeled as a log-Gaussian random field, and its covariance function is specified. Uncertainties in permeability are then propagated into the pressure field through the elliptic PDE governing porous media flow. The covariance matrix of pressure is constructed via Monte Carlo sampling. The truncated Karhunen–Loève (KL) expansion technique is used to decompose the log-permeability field, as well as the random pressure field resulting from random permeability. We find that although very high-dimensional representation is needed to recover the permeability field when the correlation length is small, the pressure field is not sensitive to high-oder KL terms of input parameter, and itself can be modeled using a low-dimensional model. Thus a low-rank representation of the pressure field in a low-dimensional parameter space is constructed using the truncated KL expansion technique.

scholarly journals On Measuring Dynamic Properties of Damping Materials Using Oberst Beam Method

2010 ◽  
Author(s):  
Hasan Koruk ◽  
Kenan Y. Sanliturk
Keyword(s):  
Material Properties ◽  
Classical Method ◽  
Dynamic Properties ◽  
Measured Data ◽  
Test Rig ◽  
Electromagnetic Excitation ◽  
Beam Experiment ◽  
Beam Method ◽  
Critical Issues ◽  
Damping Materials

The Oberst Beam Method is widely used for the measurement of the mechanical properties of damping materials. This method is a classical method based on a multilayer cantilever beam which consists of a base beam and one or two layers of other materials. The base beam is almost always made of a lightly damped material such as steel and aluminum. If the Oberst Beam Method (OBM) is to be used, it is essential to establish a very accurate measurement methodology. In this respect, the response and the excitation sensors in the Oberst test rig are generally non-contact type. Although the drawbacks of contacting type of transducers are eliminated by this way, there are other critical issues when OBM is used. It is therefore essential to be aware of the parameters that might adversely affect the measured data and also to avoid them as much as possible. Consequently, all the parameters affecting the result need to be optimized in order to obtain the material properties with high accuracy. Although the OBM is referenced in some standards and widely used in scientific studies, detailed information in the literature on how to perform a successful Oberst Beam experiment is very limited. This is the main subject this paper aims to address. In this paper, after setting up the Oberst test rig the effects of various parameters on measured data using an Oberst test rig are examined in an attempt to improve the accuracy of the estimated material properties. Then repeatability measurements are performed and the main parameters affecting the quality of the measured data are identified. After that, extensive tests are performed so as to determine the effect of the amplitude of the excitation force, adverse effects of electromagnetic excitation and the effects of length of the test specimen. Furthermore, it is found that the small differences between individual samples may also affect the results significantly. Finally, some suggestions are given to the potential users of the OBM so as to avoid undesirable effects of certain parameters during such measurements.

Study on Relationship of Ink Thickness and Color Saturation

2015 ◽  
Vol 731 ◽  
pp. 295-299
Author(s):  
Ye Chi Pang ◽  
Zhi Jie Li ◽  
Li Lin Shi
Keyword(s):  
Film Thickness ◽  
Layer Thickness ◽  
Inflection Point ◽  
Measured Data ◽  
Complex Spectrum ◽  
Offset Printing ◽  
Color Saturation ◽  
Color Quality ◽  
Relationship Of ◽  
The Relationship

In the offset printing process, the amount of ink supplying of fountain directly affects plate ink thickness, thereby affecting the color quality on the printed sheet. Ink layer thickness is difficult to judge by human eye, but we can regulate the ink thickness by detecting the color saturation. This paper describes using complex spectrum spectrometer measured data ink layer thickness and color saturation, draw two graphs of complex spectrum saturation and CIE saturation. Due to the different definitions of saturation, Cause their sensitivity of layer thickness changes response different. Two sets of data shows that the complex spectrum saturation contrast ΔS1 significantly higher than CIE saturation contrast. The data also showed that the ink color performance in terms of the relationship between layer thickness and saturation has an inflection point, the inflection point in the ink film thickness about 4μm, after reaching inflection point, even if the ink layer thickness continues to increase, there will be no significant changes in the saturation.

scholarly journals Study of Rail Squat Characteristics through Analysis of Train Axle Box Acceleration Frequency

2021 ◽  
Vol 11 (15) ◽  
pp. 7022
Author(s):  
Hojin Cho ◽  
Jaehak Park
Keyword(s):  
Surface Defects ◽  
Field Tests ◽  
Wavelet Spectrum ◽  
Measured Data ◽  
Acceleration Measurement ◽  
Field Verification ◽  
Matlab Program ◽  
General Line ◽  
Joint Section ◽  
Prototype Design

In this study, a method for detecting the railway surface defects called “squats” using the ABA (Axle Box Acceleration) measurement of trains was proposed. ABA prototype design, implementation, and field tests were conducted to derive and verify the results. The field test was performed using a proven precision measurement system, and the measured data were signal-processed using a Matlab program. The algorithm used to determine the position of the squats was developed based on wavelet spectrum analysis. This study was verified for a section of a domestic general line and, following field verification for the section, squats was detected with a hit rate of about 88.2%. The main locations where the squats occurred were the rail welds and the joint section, and it was confirmed that in some sections, unsupported sleepers occurred at the locations where the squats occurred.

Concrete Structure with Random Material Properties Undergoing Thermal Loading

2011 ◽  
Vol 250-253 ◽  
pp. 3848-3853
Author(s):  
Malgorzata Kowalik
Keyword(s):  
Partial Differential Equations ◽  
Material Properties ◽  
Finite Differences ◽  
Concrete Structure ◽  
Stochastic Analysis ◽  
Thermal Loading ◽  
Pressure Field ◽  
Theoretical Formulation ◽  
Material Parameters ◽  
Random Material Properties

Stochastic finite differences are proposed for analysis of pore pressures in concrete structure with random material properties subjected to fire loadings. The theoretical formulation of the problem is described. A system of partial differential equations is obtained and solved for first two probabilistic moments of the random pressure field. Example of stochastic analysis in concrete structure with random material parameters is given.

scholarly journals Experimental and Theoretical Analysis on the Dynamic Characteristics of Fused Filament Fabrication Plates

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Shijie Jiang ◽  
Ming Zhan ◽  
Mingyu Sun ◽  
Weibing Dai ◽  
Chunyu Zhao
Keyword(s):  
Dynamic Characteristics ◽  
Material Properties ◽  
Theoretical Basis ◽  
Mechanical Performance ◽  
Dynamic Performance ◽  
Sem Analysis ◽  
Measured Data ◽  
Fused Filament Fabrication ◽  
Dynamic Mechanical

With the increasingly wide application of fused filament fabrication (FFF) technique, the built products are inevitably exposed to dynamic mechanical loading and vibration. However, there has been no systematic study in the literature on understanding and characterization of dynamic mechanical performance for FFF products. In this paper, the dynamic characteristics of FFF plates are quantified, with the effect of different extrusion width taken into account. A dynamic model of the built plate with cantilever boundary conditions is established, and the inherent characteristics are predicted. Modal tests are then performed on these samples to obtain the measured data. Through the comparison between predictions and measurements, the theoretical model is validated. Different extrusion width makes the material properties of the plates different, resulting in different dynamic characteristics. The scanning electron microscopy (SEM) analysis on the samples confirms that the dynamic characteristic is deteriorated as the extrusion width decreases. This present work provides theoretical basis and technical support for further research in improving the dynamic performance of FFF products and helps extend the applications of this technique.

The Research on End-Point Forecast and End-Point Control of Argon Oxygen Refining Ferroalloy with Material Properties

2013 ◽  
Vol 644 ◽  
pp. 29-32
Author(s):  
Hong Di Ke ◽  
Hui Wang
Keyword(s):  
Material Properties ◽  
Forecast Model ◽  
Control Model ◽  
Measured Data ◽  
Smelting Process ◽  
Matlab Simulation ◽  
Mechanism Model ◽  
End Point ◽  
Point Control ◽  
Point Forecast

In this article, we studied Ferroalloy Smelting process, we made use of AOD furnace to smell Ferroalloy. For AOD furnace high temperature, and more dust, AOD furnace mechanism model nonlinear, and uncertainty, and strong coupled features, Aiming at these features we designed argon oxygen refining ferroally’s end_point forecast and end_point control tactics which based on online detection. Then we constructed end_point forecast model and end_point control model according to the tactics. We selected Jilin Ferroalloy 5 tons AOD furnace 50 sets of measured data,then trained and assessed the established forecast model with measured data, through MATLAB simulation obtained better of forecast results.

scholarly journals Mathematical function for the transition curves description 

2012 ◽  
Vol 51 (No. 3) ◽  
pp. 85-90
Author(s):  
R. Chotěborský ◽  
D. Herák ◽  
V. Bezouška ◽  
P. Hrabě ◽  
M. Müller
Keyword(s):  
Impact Energy ◽  
Material Properties ◽  
Impact Test ◽  
Charpy Impact ◽  
Data File ◽  
Charpy Impact Test ◽  
Measured Data ◽  
Mathematical Function ◽  
The Impact ◽  
Transition Curves

Toughness is one of important material properties. At present steel is still the most used material. Owing to the temperature this material can fail both brittly and ductily. Therefore we look for the temperature above which the material will failur ductily. The Charpy impact test is one of methods how to determine the ductility by the temperature – transition access in the determined temperature range. The measured data file is large and it requires the interlay by a curve which presents the relation between the impact energy and the temperature.

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