Applied Mechanics and Materials Vols. 511-512

Abstract: X-ray Digital imaging is an innovative method of metal fusion welding quality evaluation. To improve the accuracy, the digital imaging sensitivity must be increased by studying the optimal radioactive parameters. At first, the basic elements, inherent characteristics and imaging principle have been analysed systematically. Secondly, the optimization method of sampling rate, stacking frames, focal length, cube voltage and current have been studied based on the phisical characteristic of FPD( Flat Panel Detector). At last, the method has been verified upon two platforms. The experimental results from different systems proved correctness and applicability.

Abstract: With the rapid development of economy and society, the demand for the man-machine interactive experience is in high enhancement. Hand gesture tracking and recognition is a key technology. This paper studies the obtaining and following about dynamic hand gesture based on Kinect, which is under complex background. Not only has important theoretical significance and tracking, but also it has a broad application prospect. This paper first introduces the human skeleton tracking technology which was based on Kinect. The gesture movement orbit was acquired by tracking the hand gesture and separating the gesture from the complex background so as to lay the foundation for gesture recognition. Software was developed which can recognize human action language, control the game to respond, achieve human-computer interaction more friendly and make the game more fun by the beforehand action.

Abstract: Edge detection of color image is a difficult problem in image processing. Although a lot of corresponding to methods have been proposed, however, none of them can effectively detect image edges while suppressing noises. In this paper, a novel edge detection algorithm of color images based on mathematical morphology is proposed. Through designing a new anti-noise morphological gradient operators, we can obtain better edge detection results. The proposed gradient operators are applied to detect edge for three components of a color image. An then, the final edge can be obtained by fusing the three edge results. Experimental results show that the feasibility and effectiveness of the proposed algorithm. Moreover, the proposed algorithm has better effect of preserving the edge details and better robustness to noises than traditional methods.

Abstract: Edge detection is an old and hot topic in image processing, pattern recognition and computer vision. Numerous edge detection approaches have been proposed to gray images. It is difficult to extend these approaches to color image edge detection. A novel edge detection method based on mathematical morphology for color images is proposed in this paper. The proposed approach firstly compute vector gradient based on morphological gradient operators, and then compute the optimal gradient according to structure elements with different size. Finally, we use a threshold to binary the gradient images and then obtain the edge images. Experimental results show that the proposed approach has advantages of suppressing noise and preserving edge details and it is not sensitive to noise pixel. The finally edge images via the proposed method have high PSNR and NC compared with the traditional approaches.

Abstract: Three-dimensional scanning device will scan a large number of three-dimensional data one time, which will inevitably mixed with some of the noise points, casusing the reconstructed surfaces and curves that is not smooth. At the same time a large number of three-dimensional data can lead to reconstructing surface slow down. This paper applied Wiener-filtering which is commonly used in the gray image de-noising and smoothing treatment to filtering three-dimensional point-cloud-data by replace the gray value of gray image with a z value of point-cloud-data, and the point-cloud-data which undulates strongly will be seen as noise point and removed. At the same time using octree algorithm to streamline the data, which can be guaranteed to retain local feature point cloud data while streamlining data.

Abstract: Pressure resistant performance of Measure While Drilling (MWD) microchip tracer to withstand the harsh downhole environment is one of the key issues of normal working. Therefore, it is an effective way to analyze pressure resistant performance of the tracer in the design phase. Compressive strength of the tracer was studied based on finite element method. Considering downhole complexity and working conditions during the processing of tracer roundness, material non-uniformity and other factors. In this study, researchers took sub-proportion failure criterion to determine the failure of tracer. Simulation results of two structures, with pin and without pin, show that both structures met the requirement of downhole compressive strength, and the structure with pin was better than the structure without pin. This study provides basis for downhole application of microchip tracers.

Abstract: Fatigue of MEMS structures may occur after cyclic vibration loading, which can lead to the material degradation. A test bench was built for mechanical fatigue testing, especially for the structures that actuated by electrostatic force. A RF MEMS switch which was made of gold was tested; the material mechanical characteristic was monitored during the tests by means of the value of pull-in voltage, which is related to the change of the Youngs modulus. The fatigue stress was produced by an alternating voltage, and the amplitude of which is from 15V to 65V. The excitation frequency and the actuation time were used as a counter for the number of cycles. The results show that there is no detectable mechanical fatigue after actuation up to one billion cycles.

Abstract: LNG gains popularity as a kind of clean and efficient energy, LNG tank dome air raising installation technology is a key problem for tank construction, chain preloaded is adopted in traditional balance guidance device, the wire rope tension cant maintain a constant in air raising, which brings great safety hidden trouble. In this paper, the tension control technology based on closed-loop was put forward, the tension control device was designed and the hydraulic system principle was designed. Tensioning force can be adjusted automatically in the air raising process by researching on LNG dome air raising technology based on closed-loop tension control. It is of great significance for improving the efficiency and safety in the process of air raising .

Abstract: In this paper the characteristics of the piston features for classification and feature library; at the same time the feature size and the feature existence parametric methods are discussed in detail. In a detailed analysis of the engine piston load based on, forward piston mechanical,thermal boundary conditions, forward piston mechanical, thermal boundary conditions, the results show that the original piston has a larger reserve strength, this research provided probility for the further optimization.

Abstract: Numerical method is done on effect of wall on upwelling flow induced by air bubbler in a tank. It shows that: this reverse flow causes the increasing upwelling flow with height; when the bubbler distance to wall decreases, it is gradually only influenced at one side and then it affects the upwelling flow; the change of velocity is small in the region below bubbler. So the numerical method is helpful to describe the flow field as figures clearly and design bubbler devices in air-lift engineering applications.