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排序方式: 共有316条查询结果,搜索用时 31 毫秒
91.
92.
Theoretical analysis on hydraulic transient resulted by sudden increase of inlet pressure for laminar pipeline flow 总被引:1,自引:0,他引:1
Hydraulic transient, which is resulted from sudden increase of inlet pressure for laminar pipeline flow, is studied. The partial differential equation, initial and boundary conditions for transient pressure were constructed, and the theoretical solution was obtained by variable-separation method. The partial differential equation, initial and boundary conditions for flow rate were obtained in accordance with the constraint correlation between flow rate and pressure while the transient flow rate distribution was also solved by variable-separation method. The theoretical solution conforms to numerical solution obtained by method of characteristics (MOC) very well. 相似文献
93.
A. K. Khe 《Journal of Applied Mechanics and Technical Physics》2009,50(2):199-206
Spatial stationary flows over an even bottom of a heavy ideal fluid with a free surface are considered. Jump relations for
flows with a strong discontinuity are studied. It is shown that the flow parameters behind the jump are defined by a certain
curve which is an analog of the (θ, p) diagram in gas dynamics. A shock polar and examples of flows with a hydraulic jump
are constructed for a particular class of solutions.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 2, pp. 37–45, March–April, 2009. 相似文献
94.
G. Weber H. Berndt 《International journal of environmental analytical chemistry》2013,93(1-4):195-202
Abstract The on-line coupling of HPLC with flame-AAS using a HPF/HHPN system (high performance flow/hydraulic high pressure nebulization) is described. The proposed system is used for speciation of trace metals. High molecular weight species (protein-bound metals) as well as low molecular weight ones (organic acid complexes of metals) are separated and specifically detected. Problems arising from the flow-rate and composition of the mobile phase are discussed and it is shown that these problems can be solved by optimizing the HHP-nebulizer. 相似文献
95.
已有文献的车辆悬架控制臂液压衬套动刚度模型仅能给出动刚度变化理想曲线,不能给出动刚度的上下变化曲线。为了解决这个问题,将流体惯性系数和流量阻尼系数定义为区间变量,运用区间不确定性理论建立了液压衬套的动刚度模型。将初始区间动刚度模型获得的仿真结果与已有的实验结果对比,吻合较好,验证了该模型的正确性。采用子区间组合法,在一定的区间精度下获得优化的区间动刚度模型,进而获得优化的动刚度上下限变化曲线。区间动刚度模型为动刚度的全面描述提供了一种方法,对文献的动刚度模型进行了改进。 相似文献
96.
三轴液压仿真转台三轴相交度测试方法 总被引:2,自引:0,他引:2
根据三轴仿真转台自身的结构特点,针对决定其精度的重要环节——相交度的测试问题,提出了新的简洁的测试方法,从而为三轴仿真转台的安装、调试提供可靠数据,以保证其精度指标达到设计要求。 相似文献
97.
Flow in a porous medium with a random hydraulic conductivity tensor K(x) is analyzed when the mean conductivity tensor
(x) is a non-constant function of position x. The results are a non-local expression for the mean flux vector
(x) in terms of the gradient of the mean hydraulic head
(x), an integrodifferential equation for
(x), and expressions for the two point covariance functions of q(x) and (x). When K(x) is a Gaussian random function, the joint probability distribution of the functions q(x) and (x) is determined. 相似文献
98.
99.
Hammecker C. Barbiéro L. Boivin P. Maeght J. L. Diaw E. H. B. 《Transport in Porous Media》2004,54(2):193-219
This paper presents a simple geometrical pore model designed to relate characteristic pore radii of the porous network of soils with macroscopic infiltration parameters. The model composed of a stack of spherical hollow elements is described with two radii values: the pore access radius and the actual pore radius. The model was compared to cylindrical pore models and its mathematical consistency was assessed. Soil sorptivity S and the second parameter A of the Philip infiltration equation (1957), have been determined by numerically simulated infiltration. A diagram and an empirical relation have been set in order to relate the pore access and pore radii to the infiltration parameters S and A. The consistency of the model was validated by comparing the predicted sorptivity and hydraulic conductivity values, with the widely used unsaturated soil hydraulic functions (van Genuchten, 1980). The model showed good agreement with experimental infiltration data, and it is therefore concluded that the use of a model with two radii improves the relation between microscopic pore size and macroscopic infiltration parameters. 相似文献
100.
为了更好地分析与优化液压舵机的控制性能,根据控制理论建立了液压舵机伺服系统的数学模型;针对采用常规控制方法液压舵机系统响应速度慢、抗干扰能力差等问题,在对专家经验进行总结并获取5条控制规则后,设计了专家PID控制器;在单位阶跃信号的作用下,运用Matlab/Simulink对该液压舵机系统进行仿真;仿真结果表明,与常规PID控制、P控制相比,专家PID控制使系统调节时间缩短了0.104 s,缩减幅度达71%,受到干扰后再次稳定的时间缩短了0.034 s,有效地提高了快速性和抗干扰性,获得了良好的控制效果。 相似文献