Advanced Materials Research Vols. 287-290

Abstract: In this paper, the principle of measuring infinitesimal displacement by laser speckle is proposed to measure the velocities of particles in ER fluids. It is verified that speckles can be formed by illuminating laser beam on the starch ER fluids. The speckle patterns was recorded with high speed CCD camera, and the speckle patterns sequences with short time intervals was obtained by intercepting laser speckle video. Displacements parallel to the direction of electric field and that perpendicular to the direction of electric field were obtained by processing the two consecutive speckle patterns. The experimental results showed that the velocities of particles decreased oscillatorily with time. There is a critical electric field and a critical sample concentration, when lower than this critical electric field (concentration), the mean particle velocity increased; otherwise, it decreased.

Abstract: Owing to its unique properties and wide engineering applications, magnetorheological fluids (MRF) has become a hot study area in the field of smart materials. In this paper experimental study of the microwave reflection behavior in MRF was carried out. The results indicated that at the same frequency the microwave reflectivity of MRF decreased with the increasing of magnetic field strength; and with the particle concentration increasing, microwave reflectivity first increased, then decreased, there is a critical concentration of 15%. Under the same magnetic field, with the increasing of microwave frequency, it first decreased, there is a lowest point at 9.2GHz, and then it increased. Usually, it is considered that the change of internal structure of MRF under external magnetic field is the main reason for the regulation behavior of microwave reflectivity.

Abstract: Because weight is unsymmetrical for the robot with hand-fused foot, a method is found to calculate the centroid projection coordinate from the perspective of Newtonian mechanics. Centroid projection coordinate of the robot is detected with ARM, pressure sensors, distance measuring sensors, and multiplexer. Software is designed for the centroid projection detection from 3 aspects as multiplexer chip selection, A/D conversion operations, and centroid calculation. In the experiment, several groups of data were gained, which contained sensors data and centroid projection coordinate. Centroid projection detection has certain reference value for gait generation and path planning.

Abstract: In this paper, a series of blending films were prepared based on Polyacrylonitrile (PAN) and hydroxypropylcellulose (HPC). The phase transition temperature of these blend films was investigated by warming UV-vis spectrophotometer and Differential Thermal Scanning Calorimetry (DSC). The results showed that the phase transition temperature of HPC/PAN blend films was lower than that of HPC when adding PAN into HPC and the more PAN contents the lower LCST of blend films. The contact angle and surface image of HPC/APN blend films were studied. It was indicated that HPC could endow PAN film with not only thermo-sensitive property but also great hydrophilicity.

Abstract: It’s important to measure the horizontal distribution of the 2D velocity field for model verification and scheme selection at model test in the tidal estuary. Digital particle image velocimetry (DPIV) has become an accepted technique for the measurement of two- and three component planar velocities in a wide variety of fluid flows, which has advantages of high speed and nil interference. However, sometimes DPIV images are overexposure, uneven distribution of the gray values, and obscurity on the edges of the particles, which will affect the accuracy of flow data by inversion. Wavelet transform has good characteristics in time-frequency localization, and it has been widely used for image preprocessing, image compression, image restoration, image feature extraction and pattern recognition. A wavelet-based multi-resolution technique was applied to analyze the 2D measurement results of a DPIV system in this paper. In the different stages: boundary treatment, noise reduction, identification and elimination of the error vector, which are applicable to the processing of the DPIV information for getting the velocity vectors with higher resolution and precision through the continuous wavelet transform of velocity data.

Abstract: The aerodynamic optimization for turbocharger turbine blade is studied using variable dimensionality analysis technology. The aerodynamic optimization procedure is decomposed to two steps: two-dimensional (2D) optimization and three-dimensional (3D) optimization based on the 2D optimal results. The quintic polynomial method with continuous three order derivatives is used to present section profile of three sections, root, middle and tip of blade. The 2D aerodynamic analysis and optimization are carried separately for different sections. Aerodynamic optimization for turbine blade is driven by the combination of global and local optimization arithmetic, with the 2D optimization blade as initial value, and profile parameter as design variable. The result shows that the calculation time is shortened and the optimization efficiency is improved, compared with the full 3D optimization under the same effect.

Abstract: Data acquisition and model reconstruction of free-form surfaces with holes were been studied, based on coordinate measuring machines. First, the structural process of the parts was analyzed, the method of combinate contact measurement with non-contact measurement were used to get point cloud; Then the point cloud were been preprocessed, feature curve extracted and solid modeled; Finally, the restructure model was been quality assessed and accuracy assessed. Using the measurement of combinated contact and non-contact can also meet both the precision requirement of key part and the fast reconstruction requirement of non-critical part, which has great significance on that part to fast and accurate reconstruction.

Abstract: Assembly deformation is one of the most important factors in the aircraft thin-walled parts’ riveting, which determines the plane’s fatigue life and assembly quality. Firstly, A new type of automatic drilling & riveting system used for aircraft’s panel component riveting was studied and designed based on function modular theory. It includes system designing, modeling and assembling by using PRO/E software. Then, Rivet’s stressed deformation was analyzed through finite element analysis. It also explored the law of riveting force which changed the whole process of automatic drilling & riveting, and it can be used as a proposal to improve the riveting quality.

Abstract: The structure principle and working model of the MR fluid damper using in the automotive suspension are described in this paper. It is concluded that the damping force is related to structure parameters, shear yield stress and viscosity of MR fluid through analysis result. As the effective length of damping channel under magnet field is restricted to the configuration of MR damper, a new MR damper with optimizing the damping channel of lord RD-1005-3 MR damper is presented and mechanical models are severally established for the two MR shock absorbers. It has been shown that the maximum damping force of new damper has dramatically increased comparing with the original one through external analysis.

Abstract: Adsorption isotherms are often required for understanding mobility, fate and bioavailability of contaminants in soils. Those about Pb (II) and Cd (II) on Andosols and Kanto loam were investigated in this work. Results show that adsorption increased with cation equilibrium concentration (10^-4 - 1 meq L^-1) and solution pH (5 - 7), and also that most adsorption isotherms can be simulated precisely with the ion-exchange-based Urano model. The applicability of model in predicting adsorption equilibriums of cations on soils in circumneutral aqueous solution (pH 5 - 7) were experimentally confirmed. There is an exception as to the Pb (II) adsorption on Andosols with the solid-to-liquid phase ratio higher than 1:100, there adsorption isotherms at pH 5 and pH 7 crossed, and the measurement precision decreased. The Urano model equation becomes inapplicable. Further experiment where humus substances (HS) were added indicated that the abnormal phenomenon can be attributed to dissolved HS and their complexation with Pb (II). The dissolution of HS with solution pH has enhanced Pb (II) concentration in solution but hardly reduced the total amount of adsorption on soil.