Boundary Element Model for Nonlinear Fractional-Order Heat Transfer in Magneto-Thermoelastic FGA Structures Involving Three Temperatures

Abstract In underwater unmanned vehicles, complex acoustic transducer arrays are always used to transmitting sound waves to detect and position underwater targets. Two methods of obtaining low-sidelobe transmitting beampatterns for acoustic transmitting arrays of underwater vehicles are investigated. The first method is the boundary element model optimization method which used the boundary element theory together with the optimization method to calculate the driving voltage weighting vector of the array. The second method is the measured receiving array manifold vector optimization method which used the measured receiving array manifold vectors and optimization method to calculate the weighting vector. Both methods can take into account the baffle effect and mutual interactions among elements of complex acoustic arrays. Computer simulation together with experiments are carried out for typical complex arrays. The results agree well and show that the two methods are both able to obtain a lower sidelobe transmitting beampattern than the conventional beamforming method, and the source level for each transmitting beam is maximized in constraint of the maximum driving voltage of array elements being constant. The effect of the second method performs even better than that of the first method, which is more suitable for practical application. The methods are very useful for the improvement of detecting and positioning capability of underwater unmanned vehicles.

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Stokes' First Problem for a Thermoelectric Fluid with Fractional-Order Heat Transfer

Reports on Mathematical Physics ◽

10.1016/s0034-4877(15)60013-1 ◽

2014 ◽

Vol 74 (2) ◽

pp. 145-158 ◽

Cited By ~ 5

Author(s):

Magdy Ezzat ◽

A.S. Sabbah ◽

A.A. El-Bary ◽

Shereen Ezzat

Keyword(s):

Heat Transfer ◽

Fractional Order

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Numerical Prediction of Noise Radiated From a Panel Subjected to Boundary Layer Excitation

10.1115/imece1999-0184 ◽

1999 ◽

Author(s):

Michael Allen ◽

Nickolas Vlahopoulos

Keyword(s):

Boundary Layer ◽

Finite Element ◽

Boundary Element ◽

Transfer Functions ◽

Element Model ◽

Acoustic Response ◽

Spectral Densities ◽

Wind Noise ◽

Element Analysis ◽

Power Spectral

Abstract In this paper an algorithm is developed for combining finite element analysis and boundary element techniques in order to compute the noise radiated from a panel subjected to boundary layer excitation. The excitation is presented in terms of the auto and cross power spectral densities of the fluctuating wall pressure. The structural finite element model for the panel is divided into a number of sub-panels. A uniform fluctuating pressure is applied as excitation on each sub-panel separately. The corresponding vibration is computed, and is utilized as excitation for an acoustic boundary element analysis. The acoustic response is computed at any data recovery point of interest. The relationships between the acoustic response and the pressure excitation applied at each particular sub-panel constitute a set of transfer functions. They are combined with the spectral densities of the excitation for computing the noise generated from the vibration of the panel subjected to the boundary layer excitation. The development presented in this paper has the potential of computing wind noise in automotive applications, or boundary layer noise in aircraft applications.

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Reduced Rough-Surface Parametrization for Use With the Discrete-Element Model

Journal of Turbomachinery ◽

10.1115/1.2952379 ◽

2009 ◽

Vol 131 (2) ◽

Cited By ~ 5

Author(s):

Stephen T. McClain ◽

Jason M. Brown

Keyword(s):

Heat Transfer ◽

Rough Surface ◽

Surface Characterization ◽

Rough Surfaces ◽

Roughness Element ◽

Three Dimensional ◽

Element Model ◽

Discrete Element ◽

Diameter Distribution ◽

Discrete Element Model

The discrete-element model for flows over rough surfaces was recently modified to predict drag and heat transfer for flow over randomly rough surfaces. However, the current form of the discrete-element model requires a blockage fraction and a roughness-element diameter distribution as a function of height to predict the drag and heat transfer of flow over a randomly rough surface. The requirement for a roughness-element diameter distribution at each height from the reference elevation has hindered the usefulness of the discrete-element model and inhibited its incorporation into a computational fluid dynamics (CFD) solver. To incorporate the discrete-element model into a CFD solver and to enable the discrete-element model to become a more useful engineering tool, the randomly rough surface characterization must be simplified. Methods for determining characteristic diameters for drag and heat transfer using complete three-dimensional surface measurements are presented. Drag and heat transfer predictions made using the model simplifications are compared to predictions made using the complete surface characterization and to experimental measurements for two randomly rough surfaces. Methods to use statistical surface information, as opposed to the complete three-dimensional surface measurements, to evaluate the characteristic dimensions of the roughness are also explored.

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Two-temperature theory in magneto-thermoelasticity with fractional order dual-phase-lag heat transfer

Nuclear Engineering and Design ◽

10.1016/j.nucengdes.2012.06.012 ◽

2012 ◽

Vol 252 ◽

pp. 267-277 ◽

Cited By ~ 55

Author(s):

Magdy A. Ezzat ◽

Ahmed S. El-Karamany ◽

Shereen M. Ezzat

Keyword(s):

Heat Transfer ◽

Fractional Order ◽

Phase Lag ◽

Dual Phase ◽

Two Temperature

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Numerical simulation of thermal properties at Cu/Al interfaces based on hybrid model

Engineering Computations ◽

10.1108/ec-05-2013-0146 ◽

2015 ◽

Vol 32 (3) ◽

pp. 574-584

Author(s):

Yunqing Tang ◽

Liqiang Zhang ◽

Haiying Yang ◽

Juan Guo ◽

Ningbo Liao ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Properties ◽

Bonding Temperature ◽

Dissimilar Materials ◽

Element Model ◽

Potential Method ◽

Interfacial Thermal Resistance ◽

Interfacial Region ◽

Fe Model ◽

Content Type

Purpose – The purpose of this paper is to investigate thermal properties at Cu/Al interfaces. Design/methodology/approach – A hybrid (molecular dynamics-interface stress element-finite element model (MD-ISE-FE) model is constructed to describe thermal behaviors at Cu/Al interfaces. The heat transfer simulation is performed after the non-ideal Cu/Al interface is constructed by diffusion bonding. Findings – The simulation shows that the interfacial thermal resistance is decreasing with the increase of bonding temperature; while the interfacial region thickness and interfacial thermal conductivity are increasing with similar trends when the bonding temperature is increasing. It indicates that the higher bonding temperature can improve thermal properties of the interface structure. Originality/value – The MD-ISE-FE model proposed in this paper is computationally efficient for interfacial heat transfer problems, and could be used in investigations of other interfacial behaviors of dissimilar materials. All these are helpful for the understanding of thermal properties of wire bonding interface structures. It implies that the MD-ISE-FE multiscale modeling approach would be a potential method for design and analysis of interfacial characteristics in micro/nano assembly.

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Thermal Modeling Using Two-Port Network Impedance Fractional-Order Approximations

10.1115/detc2021-69968 ◽

2021 ◽

Author(s):

Jean-François Duhé ◽

Stéphane Victor ◽

Pierre Melchior ◽

Youssef Abdelmounen ◽

François Roubertie

Keyword(s):

Heat Transfer ◽

Frequency Domain ◽

Fractional Order ◽

Heat Dissipation ◽

Thermal Modeling ◽

Building Design ◽

Frequency Domain Analysis ◽

Conductive Heat ◽

Frequency Behavior ◽

Thermal Phenomena

Abstract Sufficiently accurate thermal modeling is necessary for many applications such as heat dissipation, melting processes, building design or even bio-heat transfers in surgery. Circuit models help modeling heat transfer dynamics: this method is simple and is often used to model thermal phenomena. However, such models well approximates low and high frequency behavior but they are not accurate enough in the middle band of interest, thus lacking of precision in dynamical terms. A more complete and accurate description of conductive heat transfer can be obtained by using a two-port network. The resulting analytical expressions are complex and nonlinear in the frequency ω. This complexity in the frequency domain is difficult to handle when it comes to control applications and more specifically in real-time applications such as surgery. Consequently, an analysis of this thermal two-port network in the frequency domain directly leads to fractional-order systems. A frequency domain analysis of the series and shunt impedances will be presented and different approximations will be explored in order to obtain simple but sufficiently precise linear fractional transfer function models. The series impedances are approximated by using asymptotic and pole-zero approximations and the shunt impedance is approximated by using a capacitance approximation and two fractional model approximations.

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