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941.
The flow of oil-in-water emulsions through quartz micro-capillary tubes was analyzed experimentally. The capillaries were used as models of connecting pore-throats between adjacent pore body pairs in high-permeability media. Pressure drop between the inlet and outlet ends of the capillary was recorded as a function of time, for several values of the volumetric flow rate. Several distinct emulsions were prepared using synthetic oils in deionized water, stabilized by a surfactant (Triton X-100). Two oils of different viscosity values were used to prepare the emulsions, while two distinct drop size distributions were obtained by varying the mixing procedure. The average oil drop size varied from smaller to larger than the neck radius. The results are presented in terms of the extra-pressure drop due to the presence of the dispersed phase, i.e. the difference between the measured pressure drop and the one necessary to drive the continuous phase alone at the same flow rate. For emulsions with drops smaller than the capillary throat diameter, the extra-pressure drop does not vary with capillary number and it is a function of the viscosity ratio, dispersed phase concentration and drop size distribution. For emulsions with drops larger than the constriction, the large oil drops may partially block the capillary, leading to a high extra pressure difference at low capillary numbers. Changes in the local fluid mobility by means of pore-throat blockage may help to explain the additional oil recovery observed in laboratory experiments and the sparse data on field trials. 相似文献
942.
M. A. Moiseev V. E. Zapevalov N. A. Zavolsky 《International Journal of Infrared and Millimeter Waves》2001,22(6):813-833
The possibilities to increase efficiency of relativistic gyrotrons by optimizing gyrotron parameters have been considered and different calculated models of gyrotrons, compared. Dependencies of the efficiency and optimal parameters on the accelerating voltage have been obtained. It is shown that efficiency of 35-45% can be achieved in a strongly relativistic gyrotron without energy recovery, and 60-70%, in the device with single stage energy recovery of the electron beam. 相似文献
943.
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945.
Ningning Yan 《Advances in Computational Mathematics》2001,15(1-4):333-361
In this paper, we present a posteriori error estimates of gradient recovery type for elliptic obstacle problems. The a posteriori error estimates provide both lower and upper error bounds. It is shown to be equivalent to the discretization error in an energy type norm for general meshes. Furthermore, when the solution is smooth and the mesh is uniform, it is shown to be asymptotically exact. Some numerical results which demonstrate the theoretical results are also reported in this paper. 相似文献
946.
In this paper, we derive gradient recovery type a posteriori error estimate for the finite element approximation of elliptic equations. We show that a posteriori error estimate provide both upper and lower bounds for the discretization error on the non-uniform meshes. Moreover, it is proved that a posteriori error estimate is also asymptotically exact on the uniform meshes if the solution is smooth enough. The numerical results demonstrating the theoretical results are also presented in this paper. 相似文献
947.
948.
949.
S. G. Jadhav T. R. Bieler K. N. Subramanian J. P. Lucas 《Journal of Electronic Materials》2001,30(9):1197-1205
Stress relaxation experiments were carried out at 25 C and 150 C on 96.5Sn-3.5Ag eutectic solder and Sn-Ag composite solder
joints (Sn-Ag eutectic solder with 20 vol.% Cu6Sn5 reinforcements incorporated by in-situ methods). The magnitude of the stress drop during relaxation depends primarily upon
the plastic shear strain imposed prior to the stress relaxation process. For sequential stress relaxation experiments that
include unloading, the stress drop is nearly independent of the accumulated plastic shear strain. However, for sequential
stress relaxation that does not include unloading, the stress relaxation is more dependent upon the cumulative plastic shear
strain history. The stress in single shear lap joints does not relax to zero stress, as is observed in stress relaxation of
bulk tension specimens, even at 150 C. Creep strain rates extracted from the relaxation data were much lower with smaller
pre-strains in both eutectic Sn-Ag and composite solder joints. The stress exponent values (n) calculated from the stress
relaxation test data ranged from 7 to 15 for both eutectic and composite solder joints, which were consistent with conventional
creep data. These stress-relaxation behaviors can be explained on the basis of dislocation recovery processes that occur during
relaxation and when specimens are unloaded. 相似文献
950.
G. Wang T. Ogawa F. Kunimasa M. Umeno T. Soga T. Jimbo T. Egawa 《Journal of Electronic Materials》2001,30(7):845-849
Hydrogen (H) plasma passivation effects on GaAs grown on Si substrates (GaAs on Si) are investigated in detail. H plasma exposure
effectively passivates both the shallow and deep defects in GaAs on Si, which improves both the electrical and optical properties.
It was found that the minority carrier lifetime is increased and the deep level concentration is decreased by the H plasma
exposure. In addition, after H plasma exposure, room temperature photoluminescence (PL) for Al0.3Ga0.7As/GaAs multiple-quantum-well (MQW) on Si is enhanced with a decrease in the spectral width. 相似文献