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81.
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83.
为了研究前坪水库右坝肩边坡在设计方案和优化设计方案开挖下的边坡稳定性分析,采用数值分析和极限平衡法进行研究,首先针对边坡典型剖面进行了数值分析,研究边坡的位移和应力分布规律,然后运用极限平衡法得出边坡的安全系数,两种方法结合不仅可以反映边坡的稳定性和位移场之间的关系,而且可以用工程界所熟悉的安全系数来评价边坡的稳定性。结果表明边坡开挖优化设计方案满足边坡稳定性规范要求,且优化方案减少了开挖量,节省了工程投资,使得工程尽早发挥效益。 相似文献
84.
A. V. Fedorov 《Combustion, Explosion, and Shock Waves》2004,40(1):17-31
A review is made of uptodate investigations in the field of physicomathematical modeling of mixing of solid particles with highvelocity gas flows arising under the action on shock waves, compression waves, and expansion waves on unstable dust deposits on the boundaries of channels or plates and in cavities, as well as on free clouds of particles. In particular, experiments in shock tubes with particles initially located in cavities and on surfaces are described. The experimental data presented in the form of distributions of particle concentrations at various points of space above the unstable layer, pressure distributions on the lower wall of the shock tube, etc., are used for verification of proposed mathematical models in regimes of single particles, interacting continua, and turbulent diffusion. An analysis of experimental and numerical data shows that the models considered sometimes allow adequate identification of the wave structure of motion of the mixture and the field of parameters inside and outside the layer. 相似文献
85.
Absorption coefficients of phytoplankton, colored detrital matter (CDM), non-algal particles (NAP), colored dissolved organic matter (CDOM), and their relative contributions to total non-water absorption (at ? w) are essential variables for bio-optical and radiative transfer models. Light absorption properties showed large range and variability sampled at 194 stations throughout Lake Chaohu between May 2013 and April 2015. The at ? w was dominated by phytoplankton absorption (aph) and NAP absorption (ad). The contribution of CDOM absorption to at ? w was lower than 30%. Phytoplankton and NAP were the primary sources of spatial and vertical variability in absorption properties. Light absorption by CDOM, though significant in magnitude, was relatively constant. CDM absorption (adg) was dominated by NAP. The spatial variation of the absorption coefficients from each of the optically active constituents were driven by several main inflow rivers in the western and middle part of Lake Chaohu. Algal blooms and bottom resuspension contributed to vertical variability as observed by phytoplankton and NAP profiles. Specific absorption of phytoplankton had significant spatial and seasonal variations without vertical variation. The spectral slope of absorption showed no significant spatial variability (p > 0.05). Variations of absorption affected different ranges of remote sensing reflectance (Rrs) spectrum, thereby increasing the difficulty of applying the remote sensing algorithm in optically complex waters. Parameters and relationships presented in this study provide useful information for bio-optical models and remote sensing of lakes similar to Lake Chaohu in terms of optical properties. 相似文献
86.
基于改进A*算法的越野路径规划研究 总被引:1,自引:0,他引:1
针对车辆的越野路径规划问题, 研究并分析了地形坡度和地表属性对于车辆路径规划的综合影响。引入了窗口移动法对地形进行先期的坡度计算和通行性分析, 就轮式车辆和履带式车辆分别建立了地表属性的粗糙度评价指标, 并采用面积占优法将地表属性栅格化。通过建立禁忌表, 叠加了坡度与粗糙度的约束影响以减少搜索范围, 提高搜索效率。构造了改进A*算法的估价函数, 并结合expand表、open表、closed表以及path表设计了考虑坡度和粗糙度约束的路径优化算法。仿真结果表明, 该算法能够快速有效地实现符合真实地形环境的越野路径规划。 相似文献
87.
Continuous-velocity lattice gas cellular automata (CVLGA) is extended to miscible binary fluid systems. A new parameter is introduced in order to control the diffusivity of the fluids. The correlation between the diffusivity and the new parameter proves that there exists the maximum value of the diffusivity. Quantitative verifications of the model are carried out with numerical simulations of the diffusion phenomena across a falling fluid film. The model is then applied to the simulations of Rayleigh-Taylor instability during the gravitational mixing phenomena. The qualitative tendency of the growth of the interface instability is the same as that obtained in conventional numerical methods. 相似文献
88.
An investigation has been carried out to attempt to understand the unusually low apparent symmetry factor observed during the reduction of V(5) at higher overpotentials at carbon electrodes (typically <0.13, or >460 mV decade−1). This reaction is of interest because it occurs in vanadium redox-flow batteries (VRBs) during discharge. Polarisation curves were measured using a rotating disk electrode (RDE). The reaction was not solution mass transport controlled, was pH independent (ca from 0 to 1), and the observed Tafel slope was unaffected by V(5) concentration over a range from 0.031 to 280 mM. Electrode double layer capacitance measurements were also carried out in sulphuric acid with and without vanadium. These tests showed that the presence of V(5) caused a suppression of the normal carbon surface quinone pseudocapacitance, as well as the appearance of two new pseudocapacitance peaks, one around 0.175-0.2 V and the other around 0.675-0.725 V versus SCE. The observed results do not appear consistent with a precipitated film causing diffusion limitations or causing IR drop. A model is developed to try to explain the data, which involves electron transfer through an adsorbed layer of vanadium. 相似文献
89.
B.S. Cheong 《Chemical engineering science》2004,59(11):2145-2157
The focus of this paper is on the effect of gravity stretching on disturbed capillary jet instability. Break-up and droplet formation under low flows are simulated using finite difference solution of a one-dimensional approximation of disturbed capillary jet instability chosen from the work by Eggers and Dupont (J. Fluid Mech. 155 (1994) 289). Experiments were conducted using water and aqueous glycerol solutions to compare with simulations. We use a gravity parameter, G, which quantifies gravity stretching by relating flow velocity, orifice size and acceleration and is the reciprocal of the Froude number. The optimum disturbance frequency was found to be inversely proportional to G. However, this relationship appears to be complex for the range of G's investigated. At low G, the relationship between and G appears to be linear but takes on a weakly decaying like trend as G increases. As flows are lowered, the satellite-free regime decreases, although experimental observation found that merging of main and satellite drops sometimes offset this effect to result in monodispersed droplet trains post break-up. Viscosity did not significantly affect the relationship between the disturbance frequency and G, although satellite drops could be seen more clearly close to the upper limit for instability at high G's. It is possible to define regimes of satellite formation under low flows by considering local wavenumbers at the point of instability. 相似文献
90.
从现场监测仪器获取的位移、应力方面的原始数据入手,绘制出位移、应力随时间变化的曲线图,并运用回归拟合分析方法,在综合分析开挖过程中各种影响因素以及锚固工具对边坡锚固效果的基础上,掌握了边坡的变形趋势及稳定状况。可为预测、预报及整治工程地质灾害等提供可靠的资料和科学的依据,为工程的安全进行提供理论保障。 相似文献