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101.
102.
S. V. Osipov 《Journal of Applied Mechanics and Technical Physics》2008,49(5):781-788
This paper is concerned with mathematical modeling and solution of the problem of the collapse of a spherical cavity in a
viscoelastic medium under the action of constant pressure at infinity. A differential equation of motion for the cavity boundary
is constructed and solved numerically. The existence of three modes of motion of the boundary is established, and a map of
these modes in the plane of the determining parameters is constructed. Asymptotic forms of the solutions of the problem for
all modes are constructed. The problem of cavity collapse with capillary forces taken into account is formulated and solved.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 5, pp. 93–101, September–October, 2008. 相似文献
103.
The effect of the loading conditions on the stability of rotating cylindrical shells is examined experimentally. It is established
that the critical loads of axially compressed rotating shells substantially decrease with increasing speed of rotation
__________
Translated from Prikladnaya Mekhanika, Vol. 44, No. 6, pp. 93–96, June 2008. 相似文献
104.
The flow behaviour of powders from a stationary shoe into a moving die, which mimics the die filling process in a rotary tablet press, was analysed using a discrete element method (DEM), in which 2D irregular shaped particles were considered. The influence of the particle shape, size and size distribution, the number of particles used in the simulation, the initial height of powder bed in the shoe, and the filling speed on the average mass flow rate and the critical filling speed (the highest speed at which the die can be completely filled) were explored. It has been found that a maximum flow rate is obtained at the critical filling speed for all systems investigated and poly-disperse systems have higher mass flow rates and higher critical filling speeds than mono-disperse systems. In addition, the powder with particles which can tessellate generally has a lower filling rate and a lower critical titling speed. 相似文献
105.
以毛细管电泳为手段,采用毛细管区段灌注技术,对麻黄碱、咖啡因和扑热息痛3种药物与牛血清白蛋白(BSA)之间的相互作用进行了研究。将两个较短的药物区带分别置于一个较长的BSA区段前后,以区段前的药物为标记物,采用峰漂移模型,同时测得麻黄碱、咖啡因和扑热息痛与BSA的结合常数,其值分别为 3.38×104 L/mol , 4.79×104 L/mol 和 6.13 ×104 L/mol 。结果表明这种方法可作为药物与蛋白相互作用分析的一种改进方法,并且有效地避免了常规峰漂移模型和迎头分析法中 相似文献
106.
基于前人模拟注射填充的显式算法,提出了一种新的全矢量化运算显式算法。对于各类注射填充的模拟,此算法避免了压力场的全局求解,矩阵操作仅在单元一级进行,通过反馈修正,在各时间增量步使已填充的区域满足不可压缩条件。由于避免了所有的全局耦合求解,计算代价与节点的自由度近似成正比,可实现填充模拟过程的高效运算。由于矢量化算法是完全脱耦的,容易实现并行计算。基于这种新算法,应用有限元法进行了注射填充仿真软件的初步开发。其填充模拟结果与商业软件MOLDFLOW的三维模拟结果比较,证实了该软件的有效性。 相似文献
107.
108.
Fluorescence lifetime measurement in the time domain requires excitation from a well separated single bunch using synchrotron light sources. In the colliding mode of the Beijing Electron Positron Collider Ⅱ (BEPCⅡ), a hybrid filling pattern was realized such that a single bunch was placed in the middle of a large gap between two multi-bunch groups. Detection of fluorescence lifetime, based on the excitation of the light pulse from this designated single-bunch, was established at Beamline 4B8 of the Beijing Synchrotron Radiation Facility (BSRF). The timing signal of the BEPCII was utilized as a trigger to gate this fluorescence event. L-Tryptophan amino acid, a known lifetime standard, was selected to assess the lifetime measurement performance. The measured lifetime was consistent in both colliding and single-bunch mode with the time resolution down to 450 ps. Moreover, both the bunch purity and the fine structure of the hybrid filling pattern were characterized. 相似文献
109.
R.D. Wiersma J.G.S. Lok L. Tiemann W. Dietsche K. von Klitzing D. Schuh W. Wegscheider 《Physica E: Low-dimensional Systems and Nanostructures》2006,35(2):320
Recent experiments on quantum Hall bilayers in the vicinity of total filling factor 1 (νT=1) have revealed many exciting observations characteristic of a superfluidic exciton condensate. We report on our experimental work involving the νT=1 exciton condensate in independently contacted bilayer two-dimensional electron systems. We observe previously reported phenomena as a zero-bias resonant tunneling peak, a quantized Hall drag resistivity, and in counter-flow configuration, the near vanishing of both ρxx and ρxy resistivity components. At balanced electron densities in the layers, we find for both drag and counter-flow current configurations, thermally activated transport with a monotonic increase of the activation energy for d/ℓB<1.65 with activation energies up to 0.4 K. In the imbalanced system the activation energies show a striking asymmetry around the balance point, implying that the gap to charge excitations is considerably different in the separate layers that form the bilayer condensate. This indicates that the measured activation energy is neither the binding energy of the excitons, nor their condensation energy. 相似文献
110.