FFT Thermoelastic Solutions for Moving Heat Sources

1997 ◽  
Vol 119 (1) ◽  
pp. 156-162 ◽  
Author(s):  
Y. Ju ◽  
T. N. Farris
Keyword(s):  
Heat Source ◽  
Frequency Domain ◽  
Hot Spot ◽  
Surface Displacement ◽  
Elastic Half Space ◽  
Heat Sources ◽  
Moving Heat Source ◽  
Line Heat Source ◽  
Pass Filter ◽  
Low Pass Filter

An analytical frequency domain solution is obtained using the spatial Fourier transform for thermal and thermoelastic fields due to an arbitrary heat source or thermal distribution moving at constant speed over the surface of an insulated, traction free elastic half space. Conversions between the space and frequency domains for the input and output are performed efficiently and robustly using FFT techniques. The method is validated by comparison to the analytical result for the moving line heat source in which it is shown that numerical evaluation of the analytical solution is problematic for large speeds or distances from the heat source. The utility of the method is illustrated on the constant patch moving heat source and discretely distributed multiple heat sources known as the “hot spot” problem. It is shown, through several examples, that the effect of hot spots on surface displacement and tangential stress is small. Finally, this conclusion is generalized by quantifying the frequency domain solution for the moving heat source problem as a low pass filter.

Surface Displacement of a Convective Elastic Half-Space Under an Arbitrarily Distributed Fast-Moving Heat Source

1965 ◽  
Vol 87 (3) ◽  
pp. 729-734 ◽  
Author(s):  
F. F. Ling ◽  
V. C. Mow
Keyword(s):  
Heat Source ◽  
Half Space ◽  
Fast Moving ◽  
Constant Velocity ◽  
Surface Displacement ◽  
Elastic Half Space ◽  
Normal Displacement ◽  
Two Dimensional ◽  
Moving Heat Source ◽  
Thermoelasticity Theory

A solution of the normal displacement of the elastic half-space under an arbitrarily distributed fast-moving heat source of constant velocity within the two-dimensional quasi-static, uncoupled thermoelasticity theory is presented. The surface of the half-space is allowed to dissipate heat by convection. Moreover, an example associated with the problem of elastohydrodynamics is given.

Thermodynamic behaviour of microstretch viscoelastic solids with internal heat source

2014 ◽  
Vol 92 (5) ◽  
pp. 425-434 ◽  
Author(s):  
Sunita Deswal ◽  
Renu Yadav
Keyword(s):  
Heat Source ◽  
Normal Mode Analysis ◽  
Generalized Thermoelasticity ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Mode Analysis ◽  
Moving Heat Source ◽  
Line Heat Source ◽  
Epoxy Material ◽  
Mech Phys Solid

The dynamical interactions caused by a line heat source moving inside a homogeneous isotropic thermo-microstretch viscoelastic half space, whose surface is subjected to a thermal load, are investigated. The formulation is in the context of generalized thermoelasticity theories proposed by Lord and Shulman (J. Mech. Phys. Solid, 15, 299 (1967)) and Green and Lindsay (Thermoelasticity, J. Elasticity, 2, 1 (1972)). The surface is assumed to be traction free. The solutions in terms of displacement components, mechanical stresses, temperature, couple stress, and microstress distribution are procured by employing the normal mode analysis. The numerical estimates of the considered variables are obtained for an aluminium–epoxy material. The results obtained are demonstrated graphically to show the effect of moving heat source and viscosity on the displacement, stresses, and temperature distribution.

Closed-Form Solutions of the Elastic Half Space due to a Line Heat Source

2014 ◽  
Vol 638-640 ◽  
pp. 2082-2091
Author(s):  
John C.C. Lu ◽  
Feng Tsai Lin
Keyword(s):  
Heat Source ◽  
Closed Form ◽  
Half Space ◽  
Hankel Transform ◽  
Elastic Half Space ◽  
Line Heat Source ◽  
Closed Form Solutions ◽  
Line Sink ◽  
Vertical Displacements ◽  
Thermoelastic Response

Thermoelastic response due to a line heat source is analog to poroelastic reaction caused by a fluid line sink. In this study, the strata are modeled as a thermoelastic or poroelastic half space bounded by horizontal surface in the mathematical model. Thermomechanics and poromechanics are applied on the formulation of basic governing equations, and an analogy is drawn to show the similarity. Using Hankel transform technique and approaching symbolic integral through Mathematica, the closed-form solutions of the horizontal and vertical displacements due to a fluid line sink are obtained. The displacements produced by the line heat source are described through analog quantities between thermoelasticity and poroelasticity. The solutions can be applied to dewater operations and build waste repository.

Analysis on Adjusting Effect and Spectral Characteristics of Digital Image Sampling

2014 ◽  
Vol 539 ◽  
pp. 471-474
Author(s):  
Hai Ying Liu
Keyword(s):  
Digital Image ◽  
Hot Spot ◽  
Modern Art ◽  
Spectral Characteristics ◽  
Image Process ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Image Sampling ◽  
Low Pass ◽  
Continuous Tone

When it comes to the digitized image, it is a process of converting analog image of continuous tone which has been sampled and quantized into digital image. The application of digital technology in modern art has become one of the hot spot in this field. First of all, this paper undertakes the digital image process of image. According to the filtering properties of the Dirac function, this paper analyzes the two-dimensional sampling principle of digital image. Based on this, the relationship between image spectrum before sampling and after sampling is compared and analyzed according to the related properties of Fourier transform. And then it is obtained that it is concluded that the ideal low-pass filter can make the sample undistorted. By further analyzing the error of the sampling value quantification processing, the rebuilt best quantitative values of image can be obtained. Thats to say, the reconstruction of digital image is the inverse process of image sampling. To a certain extent, it provides scientific theoretical basis for the integration of digital image in modern art design.

Thermoelastic Solutions for Thermal Distributions Moving Over Half Space Surfaces and Application to the Moving Heat Source

1988 ◽  
Vol 55 (1) ◽  
pp. 87-92 ◽  
Author(s):  
M. D. Bryant
Keyword(s):  
Fourier Transform ◽  
Heat Source ◽  
Half Space ◽  
Elastic Half Space ◽  
Temperature Wave ◽  
Exact Results ◽  
Moving Heat Source ◽  
Exponential Fourier Transform

A method is developed for obtaining fundamental thermal and thermoelastic solutions for thermal distributions moving over the surface of an elastic half space. This method uses the concept of a moving temperature wave along with a novel form of an exponential Fourier transform. The technique is developed and then demonstrated on the example of a moving heat source. Exact results are matched with results from Carslaw and Jaeger (1959) and Barber (1984).

scholarly journals On Relationship Between Time-Domain and Frequency-Domain Disturbance Observers and Its Applications

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Jinya Su ◽  
Wen-Hua Chen ◽  
Jun Yang
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Disturbance Observer ◽  
Matching Condition ◽  
Existence Condition ◽  
Design Guideline ◽  
Pass Filter ◽  
Functional Disturbance ◽  
Low Pass Filter ◽  
Unity Gain

This paper provides a generic analysis of the relationship between time- and frequency-domain disturbance observer (DOB) design methodology. It is discovered that the traditional frequency-domain DOBs using a low-pass filter with unity gain can only handle disturbances satisfying matching condition, while the traditional time-domain DOBs always generate an observer with a high-order. A functional disturbance observer (FDOB) is proposed to improve the existing results together with its design guideline, frequency analysis, and existence condition. Compared with the existing frequency-domain DOBs, the proposed FDOB can handle more classes of disturbances, while compared with the existing time-domain DOBs, the proposed FDOB can generate an observer with a lower-order. Numerical examples are presented to illustrate the main findings of this paper including a rotary mechanical system of nonminimum phase.

Filtering of Electronic Speckle Correlation Fringes

2012 ◽  
Vol 198-199 ◽  
pp. 1202-1207
Author(s):  
Fei Guo ◽  
Mei Zhao ◽  
Xiu Ying Fan ◽  
Jin He Bao ◽  
Wen Bang Sun
Keyword(s):  
Frequency Domain ◽  
Speckle Noise ◽  
Filter Medium ◽  
Space Domain ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Speckle Correlation ◽  
Low Pass ◽  
Mean Filter

Speckle correlation fringes include a large quantity of speckle noise. It is first to consider how to reduce speckle noise before using phase formula to calculate. Filter is usually used to reduce speckle noise. From two aspects of frequency domain and space domain, we adopted mean filter, medium filter, Butterworth low-pass filter and homomorphism filter to process the speckle correlation fringes obtained by experiment. It is shown that the speckle correlation fringes are clearer and more easily interpreted and automatic processed after being filtered.

Q-phase compensation of seismic records in the frequency domain

1996 ◽  
Vol 86 (4) ◽  
pp. 1179-1186
Author(s):  
Maksim Bano
Keyword(s):  
Wave Field ◽  
Frequency Domain ◽  
Real Data ◽  
Processing Technique ◽  
Signal Spectrum ◽  
Variable Model ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Seismic Wavelet ◽  
Inverse Q Filtering

Abstract The attenuation process acts as a low-pass filter that attenuates the high frequencies (absorption) of the signal spectrum and also changes the phase of the seismic wavelet (dispersion). Seismic frequency losses are usually recovered according to an appropriate processing technique (such as deterministic or statistical deconvolution methods), while phase distortions are generally disregarded. Therefore, accurate processing of seismic data requires a careful investigation of the relationship between absorption and phase. In this article, a procedure is presented to accomplish this goal. To account for anelastic losses, a complex power function of frequency for the phase velocity is introduced into the one-way wave-field equation in 1D. The compensation, for both effects (absorption and dispersion) described here, is analyzed in the context of wave-field extrapolation in one dimension 1D, equivalent to that in the f-k domain as phase-shift and/or Stolt migration. The phase-only inverse Q filtering works in the frequency domain. It provides for dispersion according to a constant-Q (frequency-independent) model and is valid for any positive value of Q. The extension of this algorithm for a Q depth-variable model is also shown. The amplitude compensation is accomplished through the use of a standard statistical approach. Synthetic and real data are shown to illustrate both amplitude and phase inverse Q filtering of seismic reflection records.

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