Nonuniform heating of a substrate in evaporative lithography

Traditional analysis treats the helix as a straight wire with the effects of nonuniform heating, torsion, and large curvature ignored. Using a helical coordinate system the governing partial differential equation including these effects is derived. The equation is then solved numerically using the finite element method. The results indicate a strong dependence of the temperature on the torsion parameter when the curvature parameter is significant. As the curvature parameter increases, the temperature distribution becomes skew-symmetric and the maximum temperature in the helix increases. Nonuniform heating influences the temperature distribution independent of the curvature and torsion.

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CHARACTERIZATION OF PERIODIC CYLINDRICAL SUBSURFACE DEFECTS BY PULSED FLASH THERMOGRAPHY

Surface Review and Letters ◽

10.1142/s0218625x15500328 ◽

2015 ◽

Vol 22 (02) ◽

pp. 1550032 ◽

Cited By ~ 1

Author(s):

GORAN DIKIĆ ◽

LJUBIŠA TOMIĆ ◽

VESNA DAMNJANOVIĆ ◽

BOJAN MILANOVIĆ

Keyword(s):

Thermal Flux ◽

Sample Surface ◽

Reference Points ◽

Nonuniform Heating ◽

Temperature Peak ◽

Image Recording ◽

Temperature Contrast ◽

The Difference ◽

Subsurface Defects

A characterization of cylindrical periodic subsurface defects of different sizes by means of pulsed thermography is presented in the paper. To ensure a uniform thermal flux distribution, the test samples were heated in lab conditions using two photographic flashes. Surface temperature was intentionally recorded at an angle to the normal of the sample surface. Recorded temperatures were compared with simulated temperatures and the differences in temperature peak values and temperature peak positions were noted. The thermal image was transformed based on known positions of four noncollinear points, in order to cancel out errors resulting from image recording at an angle. The uniformity of surface heating and the effect of the positions of the defects on the results were tested by means of a simulation model. The positions did not affect defect characterization. It was also found that in spite of nonuniform heating, if the reference points were selected properly, the difference in temperature contrast was negligible.

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Natural Convection in an Anisotropic Porous Enclosure Due to Nonuniform Heating From the Bottom Wall

Journal of Heat Transfer ◽

10.1115/1.3089545 ◽

2009 ◽

Vol 131 (7) ◽

Cited By ~ 19

Author(s):

Ashok Kumar ◽

P. Bera

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

Heat Transfer Rate ◽

Transfer Rate ◽

Principal Direction ◽

Orientation Angle ◽

Bottom Wall ◽

Nonuniform Heating ◽

Material Derivative ◽

Porous Enclosure

A comprehensive numerical investigation on the natural convection in a hydrodynamically anisotropic porous enclosure is presented. The flow is due to nonuniformly heated bottom wall and maintenance of constant temperature at cold vertical walls along with adiabatic top wall. Brinkman-extended non-Darcy model, including material derivative, is considered. The principal direction of the permeability tensor has been taken oblique to the gravity vector. The spectral element method has been adopted to solve numerically the governing conservative equations of mass, momentum, and energy by using a stream-function vorticity formulation. Special attention is given to understand the effect of anisotropic parameters on the heat transfer rate as well as flow configurations. The numerical experiments show that in the case of isotropic porous enclosure, the maximum rates of bottom as well as side heat transfers (Nub and Nus) take place at the aspect ratio, A, of the enclosure equal to 1, which is, in general, not true in the case of anisotropic porous enclosures. The flow in the enclosure is governed by two different types of convective cells: rotating (i) clockwise and (ii) anticlockwise. Based on the value of media permeability as well as orientation angle, in the anisotropic case, one of the cells will dominate the other. In contrast to isotropic porous media, enhancement of flow convection in the anisotropic porous enclosure does not mean increasing the side heat transfer rate always. Furthermore, the results show that anisotropy causes significant changes in the bottom as well as side average Nusselt numbers. In particular, the present analysis shows that permeability orientation angle has a significant effect on the flow dynamics and temperature profile and consequently on the heat transfer rates.

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Convection Initiation Caused by Heterogeneous Low-Level Jets over the Great Plains

Monthly Weather Review ◽

10.1175/mwr-d-18-0002.1 ◽

2018 ◽

Vol 146 (8) ◽

pp. 2615-2637 ◽

Cited By ~ 17

Author(s):

Joshua G. Gebauer ◽

Alan Shapiro ◽

Evgeni Fedorovich ◽

Petra Klein

Keyword(s):

Great Plains ◽

Three Dimensional ◽

Warm Season ◽

The United States ◽

Dimensional Structure ◽

Nonuniform Heating ◽

Low Level ◽

Low Level Jets ◽

Convection Initiation ◽

Capping Inversion

AbstractObservations from three nights of the Plains Elevated Convection at Night (PECAN) field campaign were used in conjunction with Rapid Refresh model forecasts to find the cause of north–south lines of convection, which initiated away from obvious surface boundaries. Such pristine convection initiation (CI) is relatively common during the warm season over the Great Plains of the United States. The observations and model forecasts revealed that all three nights had horizontally heterogeneous and veering-with-height low-level jets (LLJs) of nonuniform depth. The veering and heterogeneity were associated with convergence at the top-eastern edge of the LLJ, where moisture advection was also occurring. As time progressed, this upper region became saturated and, due to its placement above the capping inversion, formed moist absolutely unstable layers, from which the convergence helped initiate elevated convection. The structure of the LLJs on the CI nights was likely influenced by nonuniform heating across the sloped terrain, which led to the uneven LLJ depth and contributed toward the wind veering with height through the creation of horizontal buoyancy gradients. These three CI events highlight the importance of assessing the full three-dimensional structure of the LLJ when forecasting nocturnal convection over the Great Plains.

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A self-consistent model of second harmonic generation of laser radiation in the periodically poled nonlinear-optical crystal conditioned by its nonuniform heating

Journal of Physics Conference Series ◽

10.1088/1742-6596/1391/1/012144 ◽

2019 ◽

Vol 1391 ◽

pp. 012144

Author(s):

G Yu Ivanov ◽

P S Cherpak ◽

A V Konyashkin ◽

O A Ryabushkin

Keyword(s):

Laser Radiation ◽

Harmonic Generation ◽

Nonlinear Optical ◽

Second Harmonic ◽

Nonuniform Heating ◽

Nonlinear Optical Crystal ◽

Periodically Poled ◽

Consistent Model ◽

Self Consistent ◽

Optical Crystal

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Bolometric Properties of a Spin-Torque Diode Based on a Magnetic Tunnel Junction

Advances in Condensed Matter Physics ◽

10.1155/2019/5109765 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

G. D. Demin ◽

K. A. Zvezdin ◽

A. F. Popkov

Keyword(s):

Tunnel Junction ◽

Magnetic Tunnel Junction ◽

Nonuniform Heating ◽

Spin Torque ◽

Rectification Effect ◽

Wide Range ◽

Spin Polarized ◽

Potential Applications ◽

Dynamic Components ◽

Bolometric Effect

Spin caloritronics opens up a wide range of potential applications, one of which can be the thermoelectric rectification of a microwave signal by spin-diode structures. The bolometric properties of a spin-torque diode based on a magnetic tunnel junction (MTJ) in the presence of a thermal gradient through a tunnel junction are discussed. Theoretical estimates of the static and dynamic components of the microwave sensitivity of the spin-torque diode, related to thermoelectric tunnel magneto-Seebeck effect and the thermal transfer of spin angular momentum in the MTJ under nonuniform heating, are presented. Despite the fact that the thermal contribution to the microwave sensitivity of the spin-torque diode is found to be relatively small in relation to the rectification effect related to the modulation of the MTJ resistance by a microwave spin-polarized current, nevertheless, the considered bolometric effect can be successfully utilized in some real-world microwave applications.

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