Applied Mechanics and Materials Vol. 709

Abstract: A new gel type slow-release solid chlorine dioxide was prepared by mixing two gels together, which were Super Absorbent Polymer (SAP) absorbing sodium chlorite solution and solid acid solution, respectively. The optimal formula was determined by single factor experiment, and the effect of the temperature on chlorine dioxide release rate was investigated. Using tartaric acid as the solid acid, the release rate peak value of chlorine dioxide is 1.61 mg/h, and the release rate become slower of 1.09 mg/h at 72 h and 0.6 mg/h at 144 h, which shows a smooth and sustaining release process. When the volume of water is 25 mL, the optimal formula is SAP:3.5g, sodium chlorine:1.5g, anhydrous sodium sulfate:1.5g, tartaric acid:2g. The release process became more intense when the temperature became higher. The results indicated that this gel type slow-release solid chlorine dioxide should be suitable for eliminating formaldehyde and stink in the environment.

Abstract: The correct sonar image segmentation is an important foundation for underwater target recognition. Because the contour convergence of the active contour model depends on the selection of initial position, the active contour model is applied in sonar image segmentation. This paper proposed a selection method based on local standard deviation of image as the outline of initial contour. Due to the disturbance of noise, sonar image is usually affected in resolution and contrast. Firstly, sonar image is enhanced by top-hat and bottom-hat transformation in image morphology. Then after image enhancement, a suitable threshold value is chose for rough binarization and the standard deviation of target areas to calculate the local image. According to the size of standard deviation of different regions to determine the scope of the initial contour, sonar image segmentation is achieved by active contour algorithm.

Abstract: Traditional tooling for aircraft skin will produce a large clamping deformation of the inadequacies in the assembly process, designed a vacuum suction cup flexible assembly tooling, that tooling using vacuum suction force to clamp the workpiece in the assembly process, greatly reduces the amount of deformation of the workpiece. In order to accurately grasp the new tooling excellent performance in terms of adsorption deformation, through the establishment of a laser measuring device test platform, we conducted a large number of studies of vacuum adsorption deformation experiment on different thickness of the workpiece,has been obtained the workpiece adsorption deformation rate range under the flexible tooling system, as well workpiece thickness, sucker adsorption, the number of anchor effect on the adsorption deformation rate of the workpiece, and verify the reasonableness of the flexible assembly tooling.

Abstract: Reduction unit for high-speed train is an important component. However if faults of reduction unit occurred, the damages such as material and human damage have been caused. To prevent the damage, it is necessary to study reduction unit monitoring for high-speed train. We conducted spur gear specimen test which was crack, breakage and pitting tests and analyzed FFT, Sideband energy ratio (SER), RMS, crest factor, and kurtosis. There was not distinct difference between no-fault and pitting condition at RMS, crest factor and kurtosis. But SER increased depending on crack condition. In breakage test, all parameters had difference between no-fault and breakage condition.

Abstract: Spherical leak detectors can detect very tiny leakage in pipelines and have low risk of blockage. It is very suitable for submarine oil pipelines. In this paper, the passing ability of the detector in the vertical segment of a pipe was studied using CFD simulations. The simulation shows that the drag on the detector by the flow inside the pipe is related to the flow velocity V and the diameter ratio λ (d/D).We found it’s a good choice when λ ranges from 0.7~0.8, and a spherical leak detector (λ=0.8) is designed. The field experimentation shows that the prototype of the detector can go through within normal economical flow velocity (0.7m/s-1.5m/s) in 8 inch pipelines.

Abstract: This paper examines the basic flow and processing of the terrestrial 3D Laser scanning technology in the tunnel survey. The use of the method is discussed, point cloud data which have been registered, cropped can be constructed to a complete tunnel surface model. An example is given to extract the tunnel section and calculate the excavation of the tunnel. Result of the experimental application of this analysis procedure is given to illustrate the proposed technique can be flexibly used according to the need based on its 3D model. The feasibility and advantages of terrestrial 3D laser scanning technology in tunnel survey is also considered.

Abstract: This article mainly introduces a method that uses acoustic emission techniques to achieve on-line monitor for the shaft cracks and crack growth.According to this method,axis crack monitor is produced by acoustic emission techniques.This instrument can apply to all the pressure vessels,pipelines and rotor machines that can bear buckling load.It has the online real-time monitoring,automatic recording,printing,sound and light alarm,collecting crack information function.After a series of tests in both laboratory and field,it shows that this instrument is very versatile and possesses broad prospects of development and application.

Abstract: In order to improve the precision and reliability of the autonomous underwater vehicle (AUV) inertial navigation system, a redundant inertial measurement unit (RIMU) based on micro electromechanical system (MEMS) inertial sensors has been designed, then use support vector machine theory (SVM),construct multi-fault classifier training and combine three-step search parameter optimization method,to achieve rapid, automatic fault detection and isolation (FDI). With Monte Carlo simulation and experimental analysis, SVM method has more obvious advantages than conventional Generalized Likelihood ratio Test (GLT) on false alarm rate, undetected rate and correct isolation rate for common fault sources of RIMU, and can detect and identify the type and number of failure more effectively on redundant systems, and provide a guarantee for fault sensors isolation.

Abstract: In order to enhance the measurement accuracy of cantilever vibration gyroscope, we modify the sensitive structure of the cantilever vibration gyroscope and develop a verifiable method. Firstly, analyzing the cause of influencing the measuring accuracy and the piezoelectric plate coupling structure of the original cantilever vibration gyroscope, we propose a new piezoelectric plate coupling structure. Secondly, in order to prove engineering feasibility of new structure, we use ANSYS software to simulate the new structure with 50, 60, 100 mm cantilevers. Simulation and experiments show that the average sensitivity of the new structure gyroscope increases by 8.64%. According to these results, we can conclude that the improved cantilever vibration gyroscope can be used in engineering application.

Abstract: Reasonable number of direction finding station is examined in multi-station bearing-crossing location. Though it is believed that increasing the number of station is helpful to improve the location accuracy, In the paper, the maximum likelihood estimation (MLE) as an example. The algorithms and the location error models are given. The simulation results show that the location accuracy will be improved quickly with the increase of the number of the measuring participants, but the improvement will be sharply slowed down if too many station involved, which also boost the complexity of location.