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121.
122.
利用Love波特性计算地基动力响应 总被引:5,自引:2,他引:3
本文利用Love波弥散特性在频域上对地基出平面振动及扭振问题进行了研究。在计算区域内结构将采用有限单元划分,而在边界上则根据Love 面波特性使用传递边界有限单元。本文同时讨论了不同模态波对结构动力响应的贡献。本文方法也适合于静力分析。 相似文献
123.
In this paper, the effectiveness of the approximate motion equations of a flexible structure, obtained by the RitzKantorovich method, is analysed by using Lyapunov functions. The analysis, which is restricted to the case of a single flexible beam for the sake of simplicity, is carried out under the assumption that a partial dissipation is present, affecting only the first degrees of freedom of the system. By means of suitable Lyapunov functions, an overbounding estimate of the quadratic approximation error is determined as a decreasing function of the approximation order. The analysis is completed by considering the two ‘extreme’ cases: the theoretical absence of dissipation and the presence of structural dissipation, affecting all the infinite degrees of freedom. 相似文献
124.
非线性地基上桩结构物空间分析 总被引:1,自引:0,他引:1
本文提出了桩结构物-非线性地基空间相互作用分析的迭代法和非线性有限元法。其中,桩基分析用p-y曲线法。结合实际结构物进行了大量的计算及比较分析,成果是令人满意的,可以付诸应用。 相似文献
125.
A numerical study of the transport phenomena arising in a single-screw extruder channel is carried out. A non-Newtonian fluid
is considered, using a power law model for the variable viscosity. Chemical reaction kinetics are also included. Finite difference
computations are carried out to solve the governing set of partial differential equations for the velocity, temperature and
species concentration fields, over a wide range of governing parameters for the case of a tapered screw channel.
The numerical treatment for this combined heat and mass transfer problem is outlined. A marching procedure in the down-channel
direction is adopted and the validity of the scheme for practical problems discussed. For large viscous dissipation, the material
heats up considerably due to the prevailing shear field, affecting the viscosity significantly, and results in large changes
in the pressure development at the end of the channel. The rate of reaction controls the mass diffusion rate which in turn
affects viscosity and the flow significantly. The dimensionless throughput,q
v
, is one of the most important parameters in the numerical solution. The dimensionless pressure variation is very sensitive
toq
v
, and orders of magnitude changes are possible for small variations inq
v
. Schemes for dealing with other important effects such as back flow, heat transfer by conduction in the barrel, and the effect
of the die are also outlined.
A list of symbols is given at the end of the paper
This is publication No. F-10544-4-91 of the New Jersey Agricultural Experiment Station supported by State Funds and the Center
for Advanced Food Technology (CAFT). The Center for Advanced Food Technology is a New Jersey Commission on Science and Technology Center. This work was also
supported in part by the US Army Research Office. 相似文献
126.
A generalized kinematic viscosity-temperature correlation for undefined liquid heavy petroleum fractions has been developed to represent the data for a wide range of temperature from 100°C to 200°C. The correlation is based on the experimental kinematic viscosity data of true boiling point fractions of four Arabian crude oils. The characterization property required for estimation is 50% boiling point. The proposed correlation fits the experimental data with an overall absolute error of 6.1%. Experimental measurements of kinematic viscosity of heavy true boiling point fractions of Arabian crude oils were also obtained in order to develop the proposed correlation. 相似文献
127.
The mechanical methods based on milling rectilinear or annular grooves on a component's surface and measurement of relaxed strains are some of the most used semi-destructive methods for the determination of residual stresses. These are evaluated from the relaxed strains by means of equations based upon the linear elastic theory. In this paper the errors due to yielding localised at the bottom of the groove have been investigated. The analyses were carried out by means of the finite element technique varying the most important parameters involved. The experimental results show a good agreement with the numerical ones. 相似文献
128.
N. M. Wereley T. F. Zahrah F. H. Charron 《Journal of Materials Engineering and Performance》1993,2(5):671-682
Intelligent processing of materials (IPM) deals with the integration of process models and in situ sensors into an intelligent
process controller to achieve desired material properties. IPM-based control systems recently have been developed for both
consolidation and solidification processes. This article explores the application of models based on the finite- element method
(FEM) to develop process actuation systems, to design process schedules and component shape, and to develop a control model
with which to control the process.
The results in this article were presented at the AeroMat ’93 Advanced Aerospace Materials/Processes Conference and Exposition,
Anaheim, CA, 7–10 June 1993 相似文献
129.
Ioannis D. Moscholios Michael D. Logothetis 《International Journal of Communication Systems》2006,19(1):67-93
We consider a single link loss system of quasi‐random input, described by the Engset multirate loss model (EnMLM). Blocked calls may once reattempt to be connected to the system requiring less bandwidth; then the system is described by the single retry model for finite sources (f‐SRM). The EnMLM and the f‐SRM are extended with the single threshold finite source model (f‐STM), where calls may attempt to be connected to the system with less bandwidth requirements, according to the link occupancy, before blocking occurs. We focus on CBP equalization in the EnMLM, f‐SRM and f‐STM, under the bandwidth reservation (BR) policy. For this analysis, we apply two approximate methods, the Roberts' method and the method of reverse transition rates (RTR), which lead to a recursive CBP calculation. We evaluate the accuracy of the above models under the BR policy by comparing the analytical with simulation CBP results, based on the relative approximation errors (RAE). The results are highly satisfactory because they show that the proposed models (formulas) lead to small RAE. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
130.
This paper deals with the issues of development and implementation of a real-time NURBS interpolator for a six-axis robot. Using an open-architecture controller system as a testbed, a real-time NURBS curve interpolator was developed, implemented and tested. Sample runs were conducted with the resulting trajectories measured in real-time during robot motion. The resulting trajectories are analyzed, discussed and compared with those from a commonly used point-to-point approximation technique. The real-time NURBS curve interpolator's feasibility, advantages and related issues are also discussed. 相似文献