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Unsteady laminar boundary layers on an infinite plate including the effects of radiative heat transfer and injection or suction
on the surface of the plate have been studied. Similar solutions for the velocity and for the temperature are analyzed. Numerical
examples for velocity and temperature profiles are given. The effectiveness of transpiration cooling decreases with increasing
radiation parameter R
F. The peak temperature in the boundary layer is suppressed if R
F is high enough.
This work was initiated when the authors were Summer Consultants at North American Aviation, Inc., Space and Information System
Division in 1965 and completed at the University of Maryland and Wayne State University and was supported in part by U.S.
Air Force through AFOSR Grant No. AFOSR-1015A-67. 相似文献
25.
26.
A general nonlinear theory for the dynamics of elastic anisotropic plates undergoing moderate-rotation vibrations is presented. The theory fully accounts for geometric nonlinearities (moderate rotations and displacements) by using local stress and strain measures and an exact coordinate transformation, which result in nonlinear curvatures and strain-displacement expressions that contain the von Karman strains as a special case. The theory accounts for transverse shear deformations by using a third-order theory and for extensionality and changes in the configuration due to in-plane and transverse deformations. Five third-order nonlinear partial-differential equations of motion describing the extension-extension-bending-shear-shear vibrations of plates are obtained by an asymptotic analysis, which reveals that laminated plates display linear elastic and nonlinear geometric couplings among all motions. 相似文献
27.
Jeng-Hao Pai Wei Xu Christopher E. Sims Nancy L. Allbritton 《Analytical and bioanalytical chemistry》2010,398(6):2595-2604
Cell microarrays with culture sites composed of individually removable microstructures or micropallets have proven benefits
for isolation of cells from a mixed population. The laser energy required to selectively remove these micropallets with attached
cells from the array depends on the microstructure surface area in contact with the substrate. Laser energies sufficient to
release micropallets greater than 100 μm resulted in loss of cell viability. A new three-dimensional culture site similar
in appearance to a table was designed and fabricated using a simple process that relied on a differential sensitivity of two
photoresists to UV-mediated photopolymerization. With this design, the larger culture area rests on four small supports to
minimize the surface area in contact with the substrate. Microtables up to 250 × 250 μm were consistently released with single
10-μJ pulses to each of the four support structures. In contrast, microstructures with a 150 × 150-μm surface area in contact
with the substrate could not be reliably released at pulse energies up to 212 μJ. Cassie–Baxter wetting is required to provide
a barrier of air to localize and sequester cells to the culture sites. A second asset of the design was an increased retention
of this air barrier under conditions of decreased surface tension and after prolonged culture of cells. The improved air retention
was due to the hydrophobic cavity created beneath the table and above the substrate which entrapped air when an aqueous solution
was added to the array. The microtables proved an efficient method for isolating colonies from the array with 100% of selected
colonies competent to expand following release from the array. 相似文献
28.
V. V. Vinogradov A. V. Agafonov A. V. Vinogradov K. T. Pillai Rajesh V. Pai S. K. Mukerjee S. K. Aggarwal 《Journal of Sol-Gel Science and Technology》2011,60(1):6-10
Mesoporous γ-Al2O3 materials with high surface area and a narrow pore size distribution were synthesized by facile sol–gel procedure with application
of the polymer–colloid complex as a template. 相似文献
29.
Two novel systems are proposed to perform the electro-optic (EO) mapping of the electric-field strength close to electrode structure using CW laser diodes. By these systems, mappings of both static (DC) and high-frequency electric-field can be obtained. For the static field, the field is chopped to increase the sensitivity performance. For the high-frequency field, an intensity modulation laser, instead of a pulse laser, is used to perform the mapping measurement in frequency domain, instead of in time domain. This approach greatly simplifies the system. An experiment set-up using a vertical cavity surface emitted laser diode (VCSEL) of a wavelength 850 nm and its mapping results for a coplanar waveguide (CPW) with the signal frequency around 1 GHz are reported. 相似文献
30.
Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films
We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on
the LAO (control) and LCMO side of the substrate. Critical current, I
c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed
that while the control side showed a J
c of ∼ 2 × 106 A/cm2, the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J
c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of
J
c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection
length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length
has been quantified. A control experiment carried out with LaNiO3 deposited by PLD on YBCO did not show any evidence of self-injection. 相似文献