Applied Mechanics and Materials Vol. 274

Abstract: Friction nonlinear is common in mechatronics system. It can decrease dynamic tracking accuracy, rapidity and relative stability of the system. For NC servo system as an example the simulation analysis is carried out for friction nonlinear. Analyzing friction torque, the difference between dynamic and static friction torques have effects on the system performances. The simulation results illustrate that friction nonlinear mainly affects lower speed track performance of servo system lower. With rotation velocity instruction lower dynamic tracking accuracy and relative stability of servo system more decreasing, the response lag more severity. In the condition of rotation velocity instruction invariable, the bigger the difference between dynamic and static friction torques the worse relative stability and response lag of the system. The paper’s study has the reference value for design and improving lower speed performances of servo system.

Abstract: Considering the feasibility of the application of GIS technology and multimedia technology in campus emergency preparedness managing platform system, this paper discusses the overall design for visual campus emergency preparedness management system, where the principles of prevention and treatment for campus public emergency and this emergency preparedness visualization management system works are proposed. Then, various multimedia animation preparedness is realized by using Flash soft. By the way of analyzing various data of GIS, using professional software tool of GIS-MapInfo, taking Scilab as platform, we realize the functions of the intelligent electronic map design for HEU campus. This platform can enable visualized query and data searching, such as Eagle eye location, target finding, the shortest path searching, network communication and preparedness videos playing.

Abstract: Automated essay scoring has been the focus of a cross-disciplinary study of computer science and English instruction. In this study, an experiment was conducted to testify the validity and reliability of E-grading Device and to check out whether the holistic score generated from combining computer and human score is a better solution to automated essay scoring system. The conclusion is that e-evaluation systems are valid and reliable basically, and e-evaluation and human evaluation should be combined together to generate holistic scores.

Abstract: Since its invention in the 1990s, an immense body of academic literature on LSA regarding to Automated Essay Scoring (AES) has been published. The current study investigated the extent of applicability and usefulness of LSA-based AES for assigning English essays written by Chinese college students. The statistical results showed the application of LSA-based AES in Chinese EFL context is to the limited context. The reason is that LSA-based AES focuses on content while Chinese English writing test are grammar-oriented.

Abstract: During the use of 6－DOF(six degrees of freedom) platform the gravity center of force tends to deviate from the center of the upper platform, resulting in six rods are forced unbalanced. This paper firstly introduces the characteristics of the 6－DOF platform, then establishes simulation model of platform through the PRO/E software, and analyses the kinematics of platform by use of the ADAMS (Automatic Dynamics Analysis of Mechanical System) software, finally proceeds with dynamics analysis of six rods in unbalanced condition.Those will get the influence degree of rods under the unbalanced force,and provide some proposal for the rational use of the platform.

Abstract: Wavelet de-nosing method for complex signal is put forward in this paper. The time resolution and frequency resolution are changed as wavelet transform for signal analysis. It uses high-frequency resolution and low time resolution in low frequency analysis, and uses low-frequency resolution and high time resolution in high frequency analysis. So it fit the uncertainty principle and realize the signal time domain and in frequency domain at the same time. In this paper, the configuration of RV reducer is briefly introduced, and its fault tree is constructed taking the fault of “Output shaft can not transfer torque” as top event through illuminating potential system unit failures and analyze the effect on whole system. And then system reliability qualitative and quantitative analysis are conducted. The fault tree qualitative analysis is operated based on the minimal cut set. Followed establishing simulation model of RV reducer, system life time is obtained using Monte-Carlo random sampling method. Furthermore, system life distribution is deduced, and point and confidence interval of distribution parameters and reliability characters are given by Maximum Likelihood Estimate. Finally, simulation experiment and results analysis are given to show the effectiveness of this method.

Abstract: Feature Point Extraction Method of X-ray Image Based on Scale Invariant is proposed in this paper for industrial X-ray image with low contrast and some artifacts. First of all, the scale transformation of original image is adopted by the Gaussian kernel to building the DOG multi-scale pyramid. Then, the location and scale of the key points is fixed by the three-dimensional quadratic function. Finally, the Simply SIFT descriptor illustrates the key points. Experimental results show that the algorithm has good stability in translation, rotation and affine transformation, especially with 10 percent normalized Gaussian noise, this algorithm can still be detected feature points accuracy.

Abstract: Abstract. The supporting force model of the bionic water strider model was established through mechanical analysis, the critical conditions of which the bionic water strider model’s legs pierce the water surface were analyzed. The bionic water strider model with 4 legs was manufactured, super hydrophobic copper wire was fabricated, which was as the bionic water strider model’s legs. The maximum supporting forces of the bionic water strider model was measured through the test, which was compared with the calculated value according to the supporting force model, the error rate is 9.3%.

Abstract: The remaining oil distribution is very complex and the difficulty in tapping measures is more and more big when the west block of South-eight area has gone into the ultra-high water cut stage. So the remaining oil distribution in 109 units has been comprehensively studied on the condition that the composite water cut reaches 9.06% by establishing reservoir geologic model and proceeding reservoir numerical simulation according to recent tapping measures and remaining oil analysis experience in the process of adjusting scheme. And combined with some reservoir engineering methods such as: waterflooding characteristic curve and material balance method, obvious effects has been obtained in this research.