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21.
Experimental Study of Laminar Convective Condensation of Pure Vapor Inside an Inclined Circular Tube
Yuriy Lyulin Igor Marchuk Sergey Chikov Oleg Kabov 《Microgravity science and technology》2011,23(4):439-445
Convective condensation of pure ethanol vapor inside a smooth tube of inner diameter 4.8 mm and of length 200 mm is studied.
The experiments have been carried out at temperature 58°C corresponding to the pressure of 440 mbar, the vapor mass velocity
varying from 0.24 to 2.04 kg/(m2 s). The dependency of the Heat Transfer Coefficient (HTC) is investigated experimentally both subject to the temperature
difference between the saturated vapor and the wall and subject to the condenser inclination. The results show that the HTC
reduces with growth of the temperature difference. The dependency of the HTC on inclination has a maximum in the range 15°–35°
due to the complex gravity drainage mechanism of the condensed liquid. The results could be useful for development of compact
effective cooling systems for space and ground application. 相似文献
22.
The separation of the individual contributions of aerosol and gases to the total attenuation of radiation through the atmosphere has been the subject of much scientific investigation since remote sensing experiments first began. We describe a new scheme to account for the spectral variation of the aerosol extinction in the inversion of transmission data from occultation measurements. Because the spectral variation of the aerosol extinction is generally unknown,the inversion problem is underdetermined and cannot be solved without a reduction in the number of unknowns in the set of equations used to describe the attenuation at each wavelength. This reduction can be accomplished by a variety of methods, including use of a priori information, the parameterization of the aerosol spectral attenuation, and the specification of the form of the aerosol size distribution. We have developed and implemented a parameterization scheme based on existing empirical and modeled information about the microphysical properties of aerosols. This scheme employs the eigenvectors from an extensive set of simulations to parameterize the aerosol extinction coefficient for incorporation into the inversion algorithm. We examine the accuracy of our method using data sets containing over 24,000 extinction spectra and compare it with that of another scheme that is currently implemented in the Polar Ozone and Aerosol Measurement (POAM) satellite experiment. In simulations using 80 wavelengths in the UV-visible-near-IR spectral range of the Stratospheric Aerosol and Gas Experiment III (SAGE) instrument, we show that, for our optimal parameterization, errors below 1% are observed in 80% of cases, whereas only approximately 20% of all cases are as accurate as this in a quadratic parameterization employing the logarithm of the wavelength. 相似文献
23.
Shkuratov Y Petrov D Videen G 《Journal of the Optical Society of America. A, Optics, image science, and vision》2003,20(11):2081-2092
Using the scale invariance of classical photometry, we develop an approach to finding the photometric function of prefractal structures that form a random topography. The photometric function of the prefractal surfaces is found as the general solution of the resulting differential equation in partial derivatives. The function depends on two parameters: the number of hierarchical levels of the prefractal structures and the roughness parameter of the single-level generation. As a limiting case, the approach includes our previous theory that considered fractoids. 相似文献
24.
Numerical method for modeling the E-polarized wave scattering by electrically large quasioptical two-dimensional (2-D) reflectors is presented. Reflectors are assumed zero-thickness and perfectly electrically conducting. Efficient numerical solution is obtained from the coupled singular integral equations discretized using new quadrature formulas of interpolation type. It has controlled accuracy and deals with small-size matrices. To simulate a small-horn feeding, the incident field is taken as a beam generated by a complex-source-point (CSP) current. Presented numerical results validate empirical rule of -10 dB edge illumination needed to provide the best electromagnetic performance of reflector 相似文献
25.
Ivan Gavrilyuk Martin Hermann Volodymyr Trotsenko Yuriy Trotsenko Alexander Timokha 《Journal of Engineering Mathematics》2010,68(2):165-178
A spectral boundary problem on axisymmetric eigenoscillations of a cupola-shaped shell is considered with emphasis on small
shell thickness. The problem deals with a singularly perturbed system of ordinary differential equations. The paper examines
analytical properties of the solution and, based on that, constructs an appropriate functional basis for Ritz’ method. Employing
this basis provides fast convergence in the C
3-metrics. 相似文献
26.
H. M. Nykyforchyn O. P. Ostash O. T. Tsyrul’nyk I. M. Andreiko Yu. V. Holovatyuk 《Materials Science》2008,44(2):254-259
We show that changes in the mechanical properties of an aluminum alloy as a result of its operation or in-laboratory aging
are accompanied by a substantial change in its electrochemical properties, which can be used for control of the in-service
degradation of the material.
__________
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 2, pp. 87–91, March–April, 2008. 相似文献
27.
Irina V. Ovsienko Lyudmila Yu. Matzuy Nykolai I. Zakharenko Nykolai G. Babich Tetyana A. Len Yuriy I. Prylutskyy David Hui Yuri M. Strzhemechny Peter C. Eklund 《Nanoscale research letters》2008,3(2):60-64
It is shown that magnetometry can be employed as an effective tool to control the content of a ferromagnetic constituent in
nanocarbon materials. We propose a thermochemical treatment protocol to achieve extensive cleaning of the source nanocarbon
materials from ferromagnetic refuses. 相似文献
28.
The possibility of Bose-Einstein condensation of excitations has been discussed for a long time. The phenomenon of the phase-coherent
precession of magnetization in superfluid 3He and the related effects of spin superfluidity are based on the true Bose-Einstein condensation of magnons. Several different
states of coherent precession has been observed in 3He-B: homogeneously precessing domain (HPD); persistent signal formed by Q-balls at very low temperatures; coherent precession with fractional magnetization; and a mode of the coherent precession
in compressed aerogel. The coherent precession has been also found in 3He-A in compressed aerogel. Here we demonstrate that all these cases are examples of a Bose-Einstein condensation of magnons,
with the magnon interaction term in the Gross-Pitaevskii equation being provided by different types of spin-orbit coupling
in the background of the coherent precession.
相似文献
29.
Evgeny M. Garanin Marta S. Towers Patrick W. Toothaker Kenneth Laali Yuriy V. Tolmachev 《Polymer Bulletin》2010,64(6):595-605
Block-copolymers with highly sulfonated ionomer blocks are considered as leading candidates for low-humidity high-temperature
Polymer Electrolyte Fuel Cell membranes. We present a new approach that allows for faster measurement of conductivity of powdered
ionomers in a wide range of temperature and humidity with a single 10–30 mg sample. Our method is exemplified by a case study
of polyphenylenesufide with a degree of sulfonation 0.70. This material shows 0.12 S/cm conductivity at 127 °C and 50% relative
humidity. At higher temperatures and lower humidities, this polymer undergoes irreversible cross-linking. Further routes to
improving conductivity, chemical and mechanical properties of the polymer are discussed. 相似文献
30.