Applied Mechanics and Materials Vols. 195-196

Abstract: This paper, based on the practical demands of in-service pipeline detection, a set of X-ray digital image welding line defect intelligent recognition system is established. Taking the welding line image detected by X-ray as objects of study, self-adaptive median filter method filters noise, high frequency enhancement filter method conducts the image edge sharpening enhancement; a edge detection method for X-ray digital image based on morphological gradient is proposed; a group of characteristics parameters that accurately reflects the essence characteristic of defects is selected, using a self-organizing, self-adaptive three-layer feed-forward neural network, applying BP algorithm, the BP neural network recognition system is established, thus, to achieve detection and recognition of weld defects.

Abstract: An ultra-wideband (UWB) printed antenna with dual band-notched characteristic is presented in this paper. The proposed antenna is composed of a semi-circular patch fed by a tapered coplanar waveguide (CPW) and an unclosed ground plane, which are printed onto the same side of a FR4 printed circuit board (PCB) with an overall size of 30 mm × 30 mm × 1.5 mm. By embedding a simple arc-shaped slot in the patch and adding a T-shaped strip on the top of the patch, two notched frequency bands for rejection of WiMAX and WLAN system can be realized. The characteristics of the proposed antenna are investigated by using the software HFSS and validated experimentally, both simulated and measured results show that the proposed antenna prototype achieves good impedance matching over an frequency band from 2.1011.40 GHz for VSWR2 with two notched bands over the frequency range of 5-5.95 GHz and 3.1-3.9 GHz. Furthermore, a relatively stable gain and suitable radiation patterns are also achieved in both lower and upper UWB frequency band.

Abstract: planar double inverted pendulum is a strong coupling, uncertain and complex nonlinear system, and the dynamics model of which is the basis of control, simulation and analysis. In the paper coordinate systems of the planar double inverted pendulum were first defined, and then the dynamics model of which was built up based on screw theory and the Lagrange principle. The modeling method used being systematic and standardized, it is easy to extend to dynamics modeling of higher order planar inverted pendulums or other multi-body systems.

Abstract: We have mainly studied the main structure of wind power turbines components in accordance with the principle aerodynamics. We also have taken horizontal axis wind power turbine for example and studied the basic structure and producing technology about wheel, base and other equipments. We have computed the wind power turbines output power and efficiency, and compared with some kinds of different wind power turbines output power and efficiency. All what have studied is important to design wind power turbine.

Abstract: The axial maglev heart pump has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, small size and light weight, can effectively solve thrombus and hemolysis. Impeller is one of the important parts in the axial maglev heart pump, and its structure largely determines the blood pump performance. The research adopts fluid finite element analysis, and puts forward a method to design the impeller of axial heart pump, which took into account the small volume of axial blood pump. The Blades has been designed by calculating aerofoil bone line, and make simulation analysis for different thicken ways of blade by Fluent software, and make a conclusion that the blade thickened with certain rules has better characteristics in the same conditions. The result provides the guidance for design of axial maglev heart pump, and establishes theoretical basis for application of the implantable artificial heart pump.

Abstract: Hamstring muscle strains are one of the most frequent injuries in sports and will result in missed game time by athletes. A sudden and forceful eccentric muscle contraction during the later swing phase of sprinting may directly induce hamstring injury, so does a fast change between eccentric and concentric actions in the foot contact phase. Based on the biomechanical analysis of the hamstring muscle activities during sprinting and the studies focused on hamstring strength training, the purpose of this study is to design a strength training machine specific for hamstring. The activity of hamstring muscles during training simulated the key phase of sprinting in terms of contraction modes and loads. The design principle and usage of the machine, as well as the points for attention, are illustrated in this paper.

Abstract: In this paper, motion differential equation of the two degrees of freedom (2-DOF) vehicle is established based on the linear two degrees of freedom vehicle model and is derived without simplifying the front wheel steering angle (FWSA), then we analyze the vehicle's steady-state response , transient response and the amplitude-frequency characteristic of yaw velocity under different FWSA with the help of the matlab software and finally compare the results with the simplified ones to determine how the FWSA influences the level of the vehicle handling and stability (VHS). The results show that: while the FWSA is small, it has a less influence on vehicle handling and stability, the FWSA is large, it has a greater influence on vehicle handling and stability.

Abstract: We first have analyzed the magnetic bearing systems stability conditions, and then we have built the magnetic bearing systems stability operation module and equations. We also have analyzed the lowest speed which can sustain systems stable operation and confirmed the critical damp conditions. At last, we have designed the critical damping system.

Abstract: Not only the price of a steam cleaner but also the performance of it should be considered to improve the competitive power of the products. In this study, a steam duct was optimized by changing the length of guide line for compensating the drawback of the unbalanced mass flow rate of steam from each outlet. For evaluating the mass flow rate of each outlet, a commercial CFD(computational fluid dynamics) code was used. In the process of the optimization, SQP(sequential quadratic programming) optimization algorithm was applied. The numerical method in this study can be widely used to develop a high performance domestic steam cleaner.