排序方式: 共有28条查询结果,搜索用时 31 毫秒
11.
Rednikov AY; Zhao Hong; Sadhal SS; Trinh EH 《The Quarterly Journal of Mechanics and Applied Mathematics》2006,59(3):377-397
The steady (acoustic) streaming associated with a sphericaldrop displaced from the velocity antinode of a standing waveis studied. The ratio of the particle size to the acoustic wavelengthis treated as small but non-zero, and the solution is developedin the form of a two-term expansion in terms of the correspondingsmallness parameter. The drop viscosity is assumed to be muchhigher than that of the surrounding fluid, which is the casefor a drop in a gas medium. There are essentially three distinctregions where the steady streaming flow is analysed: insidethe drop (internal circulation), in the Stokes shear-wave layerat the surface on the gas side, and the gas outside the Stokeslayer (the outer streaming region). Solutions for the internalcirculation and the outer streaming are obtained in the limitof small Reynolds number. Despite the gas-to-liquid viscosity ratio being small, the outerstreaming may be dramatically affected by the fact that thesphere is liquid as opposed to solid. The parameter that measuresthe effect of liquidity is essentially the viscosity ratio dividedby the relative (to the particle size) thickness of the Stokeslayer. The case of a solid sphere is recovered by letting thisparameter go to zero. 相似文献
12.
13.
In this talk we present an overview of accelerator-driven sub-critical reactor systems (ADS), and bring out their attractive
features for the elimination of troublesome long-lived components of the spent fuel, as well as for nuclear energy generation
utilizing thorium as fuel. In India, there is an interest in the programmes of development of high-energy and high-current
accelerators due to the potential of ADS in utilizing the vast resources of thorium in the country for nuclear power generation.
The accelerator related activities planned in this direction will be outlined. 相似文献
14.
In vitro produced bovine embryos were frozen by pellet freezing or vitrification method. In the pellet freezing method, the embryos were cooled on the dry ice and then frozen as pellets. At warming, the pellets were immersed directly into 0.5 M sucrose. The survival rates of blastocysts frozen by the pellet freezing method were higher (P<0.01) in 40% ethylene glycol (EG) than those in the lower concentrations (20 and 30% EG). Higher survival rates of blastocysts frozen by the pellet freezing method were obtained but the development rates did not differ, as compared with those by the vitrification method. There were no significant differences between the pellet freezing and vitrification method in the frequencies of post-thaw survival of hatched blastocysts. These results demonstrate that the pellet freezing method using dry ice can be used successfully for the cryopreservation of blastocysts. 相似文献
15.
This paper describes the fabrication of a microfluidic device for rapid immobilization of large numbers of live C. elegans for performing morphological analysis, microsurgery, and fluorescence imaging in a high-throughput manner. The device consists of two principal elements: (i) an array of 128 wedge-shaped microchannels, or clamps, which physically immobilize worms, and (ii) a branching network of distribution channels, which deliver worms to the array. The flow of liquid through the device (driven by a constant pressure difference between the inlet and the outlet) automatically distributes individual worms into each clamp. It was possible to immobilize more than 100 worms in less than 15 min. The immobilization process was not damaging to the worms: following removal from the array of clamps, worms lived typical lifespans and reproduced normally. The ability to monitor large numbers of immobilized worms easily and in parallel will enable researchers to investigate physiology and behavior in large populations of C. elegans. 相似文献
16.
Polarization effects on population transfer by stimulated Raman transition using overlapping time dependent pump and Stokes
laser pulses from the ground X
1Σ
g
/+
(v
g=0, J
g=1) level of H2 to the final X
1Σ
g
/+
(v
f=1, J
f=1) level via the intermediate B
1Σ
u
/+
(v
i=14, J
i=0,2), C
1Π
u
/+
(v
i=3, J
i=2) and C
1Π
u
/−
(v
i=3, J
i=1) levels have been theoretically investigated by applying the density matrix formalism. We have studied in detail the dependence
of the population transfer on time delay between two pulses for the cases of on-resonance excitations considering linear parallel
and same-sense circular polarizations of the fields. The pump and Stokes fields are taken as having Gaussian pulse shapes
with peak intensities I
P
/0
(I
S
/0
)=2 × 106 and 1 × 107 W/cm2. Density matrix equations have been solved for each value of the magnetic quantum number M
g(0, ±1) of the initial ground level taking into account the M
g dependence of the Rabi frequencies. M
g — averaged population transfer to the final level has also been calculated. For resonance excitations to the B(14, 0) or C(3, 1) levels, appreciable population transfer is achieved for intuitive pulse order for some particular values of M
g and M
i (magnetic quantum number of the resonant intermediate level) depending on the nature of polarizations. The calculated values
of M
g — averaged population transfer for the two cases of polarizations show that for on-resonance excitation to the B(14, 0) or the C(3, 1) level, linear parallel polarization of the laser fields yield more transfer efficiency whereas for resonance excitation
to the B(14, 2) level, larger population transfer results from the same-sense circular polarizations. For resonance excitation to
the C(3, 2) level, M
g — averaged population is found to be almost polarization independent. The calculations for the six-level H2 system reveal some interesting features of polarization effects on the population transfer efficiency. 相似文献
17.
18.
Recent evidence implicating leukocytes in angiogenesis raises the question of whether leukocytes and other cells circulating with the blood in microvascular networks can home to capillary sprouts intraluminally. This study describes an investigation of leukocyte trafficking in sprouting capillaries fabricated using soft lithography. The leukocytes passing with whole blood through existing capillaries were able to enter microfabricated capillary sprouts of variable length and sprouting angle due to the mechanical interaction with red blood cells (RBCs) at the sprouting bifurcation, in spite of the complete absence of blood flow through the blind-ended sprouts or any chemoattractants. The RBCs formed "comet tails" (the densely packed cellular trains forming behind leukocytes as they move through narrow capillaries) and effectively pushed leukocytes into the microfabricated sprouts while bypassing them at the sprouting bifurcation. Individual sprouts filled with several leukocytes, as wells as RBCs and platelets, were observed. The results of this study suggest that (i) blood cells are likely present in capillary sprouts throughout their development, (ii) leukocytes and other circulating cells may use this mechanism to home to capillary sprouts intraluminally for direct engraftment, and (iii) tissues may use this phenomenon as another mechanism for local recruitment of leukocytes from the blood stream. 相似文献
19.
In this paper the singularly perturbed initial boundary value problems for the nonlocal reaction diffusion system are considered. Unsing the iteration method and the comparison theorem, the existence, uniqueness and its asymptotic behavior of solution for the problem are studied. 相似文献
20.
E. V. Shevkoplyas 《Journal of Mathematical Sciences》2014,199(6):715-722
We study optimal solutions in differential games with random duration. 相似文献