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661.
This paper presents an application of strut-and-tie model (STM) to design the interior anchorage zone (IAZ) in the post-tensioned
concrete structure. The STM theory and range of IAZ are introduced. Then, based on the finite element analysis, a series of
simplified equations to calculate internal forces in IAZ are presented. Finally, the STM model for IAZ is given. In the proposed
STM model, internal forces in ties vary with the dimension ratio and the eccentricity of load. The U-turn of internal forces
is suggested to allocate rebar to resist bearing flexural tensile force. Compared with the FIP (International Federation for
Prestressing) model, the proposed STM model is more reasonable and applicable. 相似文献
662.
Phase space can be constructed for N equal and distinguishable binary subsystems which are correlated in a scale-invariant manner. In the paper, correlation coefficient
and reduced probability are introduced to characterize the scale-invariant correlated binary subsystems. Probabilistic sets
for the correlated binary subsystems satisfy Leibnitz triangle rule in the sense that the marginal probabilities of N-system are equal to the joint probabilities of the (N −1)-system. For entropic index q ≠ 1, nonextensive entropy S
q
is shown to be additive in the scale-invariant occupation of phase space. 相似文献
663.
Petal failure characteristics of a conical projectile penetrating a thin plate at high oblique angle
In order to determine the impact depth of a conical projectile impacting a thin plate at high oblique angle, the residual
velocity of the projectile after penetrating must be known. Based on the petal failure mode of the conical projectile impacting
the thin plate at high oblique angle, the energy consumption mode of the target was determined. During the perforation process,
the energy consumption of the target was completed by the saucerization, the power work of the petals, the propagation of
radial cracks and petal bending. The energy formula was deduced for each energy dissipation mode and the energy consumed in
the impact process was determined. The residual velocity and the ballistic limit velocity of the projectile were deduced by
energy conservation principle. Comparison of the analytical results of the residual velocity to the numerical results demonstrates
the accuracy and reliability of the analytical formula. 相似文献
664.
A new solution to the inverse position analysis of the redundant serial robot is presented. The inverse position analysis
problem of the redundant serial robot is transformed into a minimization problem and then the optimization method is adopted
to solve the nonlinear least square problem with the analytic form of a new Jacobi matrix. In this way, the inverse solution
of the redundant serial robot can be searched out quickly under the desired precision when the positions of the three non-collinear
end effector points are given. The inverse position analysis of the 7R redundant serial robot is illustrated as an example
and the simulation results verify the efficiency of the proposed algorithm. 相似文献
665.
The steered covariance matrix (STCM) and its inverse matrix should be calculated in each beam for steered minimum variance
(STMV). The inverse matrix needs complex computation and restricts its application in engineering. Combining the integration
character of one-phase regressive filter with the iterative formula of inverse matrix, an STMV iterative algorithm is proposed.
The computational cost of the iterative algorithm is reduced approximately to be 2/M times of the original one when there are M sensors, and is more advantaged for the realization of the algorithm in real time. Simulation results show that the STMV
iterative algorithm can preserve the characters of STMV on high azimuth resolution and weak target detection while the computational
cost reduced sharply. The analysis on sea trial data proves that the proposed algorithm can estimate each target’s azimuth
even when the source powers differ in large scales or their bearings are very approximate. 相似文献
666.
Turbulence enhancement by particle wake effect is studied by numerical simulation of gas turbulent flows passing over particle
under various particle sizes, inlet gas velocities, gas viscosity, gas density and the distance of particles. By performing
dimension analysis and using the form of gas-particle interaction source term for reference, a new semi-empirical turbulence
enhancement model by the particle-wake effect is proposed. The turbulence model is then incorporated into second-order moment
model for simulating gas-particle flows in a horizontal channel with different wall roughness and a sudden-expansion chamber.
The results show that this model is with higher calculating accuracy than another two turbulence models in comparison with
the experimental results. 相似文献
667.
Based on the Hamilton principle, dynamic differential equation of the submarine pipeline span, under the interaction of internal
flow and external environmental loads, is established. A constraint-equivalent method is used to deal with the boundary conditions
of pipeline span on the linear elastic seabed. Effects of the internal flow velocity and seabed stiffness on the pipeline’s
lateral deformation and bending stress are studied by the static analysis, while the preliminary relationships between the
internal flow velocity and the foundation stiffness to the natural frequency of pipeline span are investigated by the dynamic
analysis. It is found that the lateral deformation increases with the increment of internal flow velocity, but decreases with
the increment of seabed stiffness. The bending stress at the ends of span increases with the increment of internal fluid velocity
and the seabed stiffness, however the stress at the middle of the span shows the converse tendency. Moreover, increasing the
seabed stiffness or decreasing the internal flow velocity can lead to higher natural frequency. The dynamics response of midpoint
of span at different foundations and internal fluid velocities are also given in this paper. 相似文献
668.
A source-to-far-field computation procedure aiming at predicting the noise generated by the underwater propeller was presented.
Detached eddy simulation (DES) was used to resolve the unsteady flow field, which was taken as input data as noise propagation.
Far-field sound radiation was performed by means of Ffowcs Williams-Hawkings (FW-H) equation. The computation procedure was
finally applied to a typical marine propeller, David Taylor Model Basin (DTMB) 4118. The sound pressure and directivity patterns
of this propeller were discussed. 相似文献
669.
Evaluation industrial factory building damage potential due to ground movements caused by excavations inside the building is a critical design consideration when reconstructing the underground equipment of the industrial factory building. In this paper,the behavior of a support system for a reconstruction project of underground equipment of the industrial factory building in Shanghai and its effects on a pile-foundation supported building are presented. The 8.1 m deep excavation is made through soft clay to... 相似文献
670.
When diaphragm wall is used as the permanent vertical bearing structure,design standard of the bored pile adopted has to induce the risk or iste. The vertical load transfer mechanism and bearing capacity of the diaphragm wall are examined by a field testing program at the site in Shanghai soft clays. Test results indicate that the diaphragm wall almost behaves as a rigid body under the vertical load. It induces that the skin friction and the toe resistance of the wall develop simultaneously. The skin fricti... 相似文献