Applied Mechanics and Materials Vols. 278-280

Abstract: To solve the problem of speckle noise, CCD photoelectric noise and background light noise in non-diffracting beam triangulation and improve measurement accuracy and resolution, we use gray dynamic filtering theory. In the non-diffraction beam triangulation measurement system, the measured signal is reconstructed at the maximum peak of the spots by implementing the dynamic GM genetic filtering methods based on the grey system theory. There are only four main steps of modeling. The first step is to update the system dynamically and continuously. The second step is to effectively obtain low frequency trend component,The third step is solving the problem of the low rate of complex multi-measurement.The last is solve the problem of the limit of unsuitable online measurement. This method of triangulation measurement based on the non-diffracting beam have higher measurement accuracy and higher resolution over the traditional laser triangulation measurement system.

Abstract: The process of coordinate measurement involves a large amount of data. This paper uses the IDEF0 and DFD model to analyze the measuring function requirements for solving the problem of ambiguous internal information flow and material flow during the measuring process and uses IDEF1X method to constitute information model of coordinate measurement. The information is extended on the three-dimensional model generated by using the MBD (model based definition) technology. It enables us to specify the measurement process and reduce the specification uncertainty of the digital measuring system. In addition, the extended information could have been inputted for the subsequent process such as process planning, data analysis and evaluation of measurement results.

Abstract: In order to realize the correspondence of feature points in the binocular dynamic vision measurement system, the two homologous images matching problem in the paper is studied. First of all, a method of strong space resection. The strong space resection optimizes the elements of exterior orientation, improves the precision, so as to improve the calculating precision of epipolar line. Secondly, an algorithm of multiple restriction matching which is for two homologous images matching of feature points has been introduced. This algorithm based on epipolar line constrain, increases the uniqueness constraint and double constraint, combined with the second match with disparity gradient constrain, finally get the correct matching relationship of feature points in two homologous images. The experimental results show that: this method for matching of binocular dynamic vision measurement system, can get 100% of the matching accuracy rate. And it would satisfy the need of binocular dynamic vision measurement system.

Abstract: Based on environmental stochastic excitation, a large scale modal test was conducted at an important section of Shanghai Metro Line 1. According to the collected time response data, the natural frequencies of the soft soil-tunnel system were obtained by means of theoretical and experimental analysis, which can provide calculation parameters for further relevant dynamic analysis.

Abstract: Dispersion relation for the p-wave sound speed and attenuation has been described by several models based on continuum or scattering theory. As an alternative approach, this study proposes a model describing relation for the p-wave in case of elastic grain scatterers existing in background fluid medium. Dispersion relations are shown as a function of different grain size distribution and Rayleigh parameter . For quantitative analysis of the proposed model, experiments are performed using water-saturated glass beads. Two sets of experiments employing unimodal and bimodal grain size distributions are performed and used for comparison with the current proposed model.

Abstract: In the belief function theory framework, how to measure conflict between evidences is the first step in the combination of conflicting evidences. However, the existing conflict measurement methods have some limitations. Two new methods based on binary function of the combined belief assigned to the emptyset before normalization and the distance betting commitments of beliefs are proposed. Two methods have three advantages. Firstly, they are more suitable for people's intuitive logic reasoning. Secondly, they overcome the operational problem of the existing binary conflict measurement methods. Thirdly, new methods can measure the conflict between any pieces of evidence simultaneously, which can satisfy the interchangeability and combinability. Some illustration results are presented to demonstrate the effectiveness of the improved methods.

Abstract: Based on the wing damaged aircraft for background, the online identification method of mutational parameters was studied. After structure damaged, the symmetry of the aircraft was broken, causing the pneumatic structure of the vertical and horizontal highly coupled. To identify the aerodynamic parameters, firstly aerodynamic forces and moments were estimated as the output data of identification. Then the model of identification was selected according to the coupled pneumatic structure. Finally an identification method called Limited Recursive Least Squares (LRLS) was introduced, in which forgetting factor, weight matrix and limit item were used. The simulation results show that this method is capable to resolve the problem of strong coupling and sudden changing, while meeting the real time and accuracy requirement of online identification.

Abstract: During the production of the low-pressure casting aluminumwheel hub, the head face deformation and axial deformation of the casting blank are always happened due to various factors.The casting wheels beyond tolerance are considered as waste products with no need for further machining. Traditionally, the measurement of the deformation is usually static and by handwork,which limits the accuracy and reliability. This paper introduces anon-line automatic measuring system for casting wheels based on laser measuring technology. The configuration of the system and measuring method are presented in detail. Test results showed that the system could meet the measurement requirements: the whole measurement process operated quickly with the total time of 30s; the dimensional accuracy reached 0.02mm while the measurement error of the deformation was within 0.04mm. The system achieves better repeatability and reliability compared to the manual measurement.

Abstract: According to the reasons and features of car accidents happening in vehicles’ side areas, this paper designed and developed a kind of automotive lateral anti-collision warning system by frequency modulation continuous wave, based on the research on 24GHz linear frequency modulation continuous wave radar-probing system. The system designed in this paper will forecast the potential danger to drivers and avoid the accidents. The hardware structures, algorithm, program flows and working patterns of the warning system were introduced. Furthermore, pointing to the problem of false alarms, a kind of filtering method was presented creatively. This method improved the reliability of the warning system and the accuracy of the forecast. It filtered the disturbance coming from the side of the vehicles, and solved the difficult problem that prevented the millimeter-wave radar from being applied in automotive lateral anti-collision warning system. Finally, the experiment was designed and carried out. The result verified the rationality of the solution and the practicality of the system’s function.

Abstract: There are a large number of sensors to detect information in mine environment system, which provides the original data for the prevention and treatment of mine accidents. According to data flow of data acquisition, data transmission, data storage and data processing, this paper used CC2530 to design the wireless sensor nodes, analyzed the Zigbee network topology underground and designed an optimized PEGASIS protocol. The multi-sensor data fusion method was applied to the multi-parameter and large-scale mine data, solved the nonlinear problems in the multi-feature selection and extraction and also improved the performance of mine monitoring system.