Applied Mechanics and Materials Vols. 668-669

Abstract: Water filled pipe as an experimental model of the sea pipeline on ships, the study has very important significance of the sound propagation characteristics. In this paper, eigenfunctions of pipeline interior sound field are theoretically calculated at first. And through the Matlab software simulation calculation, the cutoff frequency is shown. And then, the water filled pipe acoustic insertion loss is given by the experimental study. Through the research, we validate the cutoff frequency calculation, and gives the insertion loss of pipelines.

Abstract: Based on the PDF transport equation of particle, Using both non-isotropic correlation coefficient and isotropic correlation coefficient, the two-order moment trajectory model of particles (TOMTM) is used to simulate the backward-facing step two-phase flow. It is shown that the isotropic correlation coefficient of TOMTM can simulate the anisotropic turbulence of particle better.

Abstract: Based on the PDF transport equation of particle, a two-order moment trajectory model of particles (TOMTM) is proposed to obtain reasonable statistical characteristics of a two-phase flow. Using the method proposed by Risken, It is shown that TOMTM is just the solution of the particles PDF equation

Abstract: A lumped mass method is presented to analyze the tension force subjected by flexible mattress and its configuration. The method can take account of the elastic extension, non-uniform mass distribution of the mattress and the acting force due to flowing water. Through comparison between calculation results of this paper and catenary theory, it verifies the lumped mass method is more applicable for analysis of flexible mattress in real fluvial environment than commonly used catenary theory.

Abstract: In this paper, numerical simulation of natural convection in a closure square cavity with heating source on the basement is carried out using thermal lattice Boltzmann method. The purpose of this work is to analysis the physics of mass and heat transfer in such a condition. For different Rayleigh numbers, the relative heating area ratio is changed in the range of 0.1-1.0, correspondingly. It is found that the flow pattern is symmetrical for increases from 10³ to 10⁶, and the boundary layers at low temperature become thinner, also the circulation rate is higher. For a special Rayleigh number, is as a monotone increment function of relative heating area ratio, and the value of which almost increases linearly when the area is below 0.8, and then reach to its maximum exponentially.

Abstract: Physical model and numerical simulation model for oil-air annular flow through conical diffusers are built by Fluent, and Coanda Effect, a commonly phenomenon, appeared in this kind of oil-air annular flow field is studied, especially influences of Coanda Effect on the attachment of the liquid phase of annular flow trended to the curved wall are analyzed in detail by changing expansion angles to calculate the radial pressure distribution and pressure drop, employed numerical simulation method, in this paper. The simulation results show that the expansion angle has a great influence on the attachment of liquid phase in annular flow to the curved wall, the radial pressure gradient is an important factor of the Coanda Effect which make the liquid phase of annular flow convey near the wall, and the radial pressure gradient will decrease but the pressure drop increase when the expansion angle becomes larger. These conclusions will provide useful reference in designing pipelines conveying the two-phase annular flow in oil-air lubrication system.

Abstract: Orthogonal experiments on oil content are done on a test rig in our lab by ECT (electrical capacitance tomography) technology under different experiment data groups which includes 3 kinds of characteristic parameters, such as air pressures, oil volume-per-cycle and lubrication cycle, of the system. The influence degree of the three characteristic parameters on oil content is sorted, and then the optimum experimental conditions resulted in the smallest oil content and the most stable distribution of oil film are obtained respectively from the experiments, and finally the change trend of the effect of lubrication cycle on the oil content is got by changing lubrication cycle, one of the 3 characteristic parameters, at a time and keeping 2 left characteristic parameters at the best level above proposed. These results will help us to research and apply further in the oil–air lubrication system.

Abstract: Modern avionic software usually runs on the ARINC653-compatible OS based on the Integrated Modular Avionics (IMA) architecture. Although existing ARINC653 annex of Architecture Analysis & Design Language (AADL) can be used to construct IMA models straightforward, it is still hard and error-prone work for avionics engineers because of the complexity of ARINC653 and manual modeling. Therefore, a hierarchical transformation-based approach is proposed to obtain correct IMA models step by step from general AADL models, rather than its ARINC653 annex. The typical transformation algorithm is given and a tool is also developed to help accomplish this approach automatically and effectively.

Abstract: Robot manipulator position and posture control is a popular topic in the field of uncalibrated visual servoing, this paper presents a kalman filter-based robot manipulator five-degrees of freedom uncalibrated vision positioning method. In the case of the fixed binocular cameras and manipulator parameters are unknown; firstly, the specific point and angle image features information in the camera image space were selected in order to describe the relative pose relationship between robot manipulator ends and goals. Then, the kalman filter online estimation algorithm was applied to calculate image Jacobian matrix which is mapping relationship between image space to cartesian mission space, and vision controller was designed in the image plane realized robot manipulator five-degrees of freedom uncalibrated vision positioning control. Finally, Six-degrees of freedom robot manipulator’s five-degrees of freedom uncalibrated visual positioning Simulink model established in the Matlab environment, and the simulation result show that kalman filter online estimation method made the robot manipulator rapid convergence to the desired position and posture with high accuracy.

Abstract: Based on kinematics characteristic of two-wheeled differential drive mobile robot (WMR) and response characteristic of fact motor drive system, this paper presents the analysis method of the equivalent rotation inertia, and the entire vehicle load is assigned to each wheel, and then the wheel load is converted into the corresponding equivalent rotation inertia of the motor shaft of each wheel, and motion model of WMR are obtained for combining with quasi-equivalent (QE) state space model of double-loop direct current motor systems under variable load and kinematics model of WMR under the load changes. By using speed response data of the actual system and combining with genetic algorithm to accurately identify the model parameters. Finally, through experiments results of the WMR motion model and the second order model respectively comparing with the actual system which demonstrates the effectiveness of the proposing method and model.