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排序方式: 共有374条查询结果,搜索用时 31 毫秒
31.
Jackson Crane Xian Shi Jonathan T. Lipkowicz Andreas M. Kempf Hai Wang 《Proceedings of the Combustion Institute》2021,38(3):3585-3593
A geometric model with a low computational complexity capable of simulating detonation behavior in physical systems is proposed. In support of the geometric model development, a series of cylindrical 1D simulations with a variable size initiation kernel are performed in hydrogen-oxygen mixtures. From these 1D simulations a detonation cell stabilization mechanism is identified. The stabilization mechanism is predicated on the size of the gap between the pressure and temperature fronts at the point where the average pressure front velocity along one cell length is equal to the CJ velocity. This gap, in a multidimensional detonation, is the ignition kernel of a subsequent blast, and dictates the formation of the subsequent cell. Serial analysis of blasts in this context leads to a unique stable blast kernel size for any mixture, which, within the uncertainty of the initial kernel state, can predict the experimental cell length for mixtures considered in this study. Using a tabulation of the 1D simulations as an input, a formulation and sample results of the geometric model are shown. The geometric model can reproduce both qualitative and quantitative features of experimental detonation cellular structure. 相似文献
32.
Prins-type macrocyclizations have recently emerged as a successful strategy in the synthesis of polyketide-derived natural products. This reaction provides a concise and selective means to form tetrahydropyran-containing macrocyclic rings of varying size. A high degree of functionality within the macrocycle is tolerated and the yields for these transformations are typically good to excellent. Since the initial report of a Prins macrocyclization reaction in 1979, examples of this approach did not re-emerge until 2008. However, the use of this method in natural product synthesis has rapidly gained momentum in the synthetic community, with multiple examples of this macrocyclization tactic reported in the recent literature. 相似文献
33.
Sparse asymptotic minimum variance based bearing estimation algorithm for a single vector hydrophone
For underwater target detection using a single vector hydrophone, sparse asymptotic minimum variance(SAMV) method is used to estimate the target bearing. The SAMV discretizes the entire scanning space and the target bearing is located at the position of the discrete direction. The SAMV algorithm utilizes the sparsity of the spatial signal to improve the estimation performance of the target bearing. Background noise level(BNL) of the bearing estimation of SAMV algorithm is lower than those of the conventional beam forming(CBF)method and minimum variance distortionless response(MVDR) method for different signal noise ratios(SNRs). When the SNR is higher than 0 d B, the direction-finding error of this algorithm is less than 2°. Moreover, the SAMV algorithm has a better dimensional orientation resolution capability. The experimental results show that the SAMV algorithm gives a bearing and time recording map with a lower BNL, which effectively verifies the effectiveness of SAMV algorithm in terms of underwater target detection. 相似文献
34.
L. J. Crane A. G. McVeigh 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2011,52(6):365-376
This study deals with boundary layer flow along the entire length of a stationary semi-infinite cylinder under a steady, accelerated
free-stream. Considering flow at reduced dimensions, the no-slip boundary condition is replaced with a Navier boundary condition.
Asymptotic series solutions are obtained for the shear stress coefficient in terms of the Bingham number that corresponds
to prescribed values of both the slip coefficient and the index of acceleration. By investigating motion at small and large
axial distances, the series solutions are presented. For flow in the intermediate distances, exact and interpolated numerical
solutions are obtained. Using these results, the shear stress along the entire cylinder wall is evaluated in terms of the
parameters of acceleration and slip. 相似文献
35.
36.
L. J. Crane A. G. McVeigh 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2010,61(3):579-582
This paper is concerned with uniform axial flow of a gas along a semi-infinite microcylinder in the slip regime. Following Glauert and Lighthill (Proc R Soc 230A:188–203, 1955), the effect of slip on the skin friction is investigated by employing an asymptotic series approach for large axial distances along the cylinder. 相似文献
37.
分别采用全多孔型硅胶基键合强阴离子交换柱与氨丙基键合硅胶柱,在低波长 200 nm 处检测,分离测定了磷霉素 探讨了流动相条件,如p H 值、离子强度等对磷霉素保留及分离选择性的影响,优化分离条件,建立了一种测定磷霉素的高效液相色谱新方法方法简便、快速 相似文献
38.
Experimental Techniques - 相似文献
39.
R.I. Crane 《International Journal of Heat and Fluid Flow》1982,3(1):13-20
The numerical turbulent coalescence/deposition model of Crane and Williams has been used to indicate likely trends in the development of drop size distribution and entrained water flow rate in the cross-over pipes of a nuclear wet steam turbine. Large increases in mean drop diameter have been shown to be possible, the results being very sensitive to the width of the initial size distribution, the entrained wetness fraction and the turbulence intensity. Deposition rate was also found to be strongly dependent on turbulence intensity, but inertial deposition onto and re-entrainment from the turning vanes of a bend did not significantly influence subsequent coalescence and turbulent deposition rates in the single example computed 相似文献
40.
Naturally occurring Görtler vortices have been investigated, using laser anemometry, in the laminar concave-surface boundary layers of water channels with 90° bends. Distributions of streamwise and spanwise velocities are presented, supported by flow visualization. Amplification was found to cease at Görtler numbers in the region of 9, followed by increasing distortion and spanwise wandering of the vortices. Development of a vortex system from an imposed disturbance has also been predicted by numerical computations. 相似文献