Abstract: This paper addresses how to discover wind erosion of aircraft components in time and to take appropriate measures to repair and prevent damage, thereby reducing the cost of aircraft maintenance and prolonging aircraft service life. The authors of this paper have extensively compiled and studied civilian aircraft maintenance data in the recent years from Guangzhou Aircraft Maintenance Engineering Co. Ltd. In this paper they discuss the aircraft components most susceptible to wind erosion, as well as repair methods and prevention mechanisms. These findings can serve as a reference and a guide to civilian aircraft flight maintenance, repair, and routine inspections.
Abstract: There are many kinds of Ecological-type revetment, including types of Natural vegetation, Masonry, Eco-Concrete and so on. What is more, the engineering characteristics, economic cost, suitable condition of application are all different. Therefore we should choose appropriate types of ecological-type revetment in the construction of river channel for small cities and towns. This article includes the overview of the progress of ecological-type revetment rectification measures, the types and characteristics of ecological-type revetment. Selection principles of economics, security, aesthetics as well as the consideration of the idea of harmonious coexistence between man and water in ecological-type revetment construction are proposed.
Abstract: A novel trans-scale precision positioning stage based on the stick-slip effect was developed. Combining with LuGre friction model, the flexible movement model of the stick-slip driving was established and simulated in Simulink software. Simulation analysis got the displacement and speed curve of slider and the net displacement of each step was calculated. The movement of slider lags behind the PZT actuator. The testing prototype of the stage driving by stick-slip effect was designed and the movement parameters of forward and reverse direction was tested, the results of movement model and simulation was verified by the testing datas. The problem of the difference of forward and reverse movement was proposed.
Abstract: The main cause of cement concrete pavement fracture is void beneath slab, while water is an important factor of void beneath slab. In order to clearly understand impact of water on void beneath cement concrete pavement, this paper analyzes penetration soaking role and scouring of water and studies the evolution process of void under slab. It is founded that the erosion of the grassroots and void beneath the plate influence each other. Conducting a Small-size simulation test by using Falling Weight Deflectometer (FWD), the movement condition of the water in empty area under concrete road and the effect of void size on current scour are got under the action of moving load.
Abstract: There has been explosive demand for supporting multi-class traffic, especially bandwidth-intensive multimedia traffic in wireless networks. The ability to manage bandwidth to cope with wireless network resource fluctuations is becoming increasingly important. In this paper, we propose an efficient Call Admission Control (CAC) scheme that relies on adaptive and dynamic resource reservation strategy for multi-class service wireless networks. Extensive simulation experiments have been conducted to evaluate the performance of the proposed scheme. Results show that our proposed adaptive scheme is effective in guaranteeing QoS requirements by keeping the call blocking and handoff dropping probabilities substantially low.
Abstract: With the methods of macrostructure observation and temperature measurement, the paper has studied the influence rules of static magnetic field on 2024 aluminum alloy solidification structure and solidification rate. The conclusions can be concluded as follows: the static magnetic field can inhibit the growth of columnar crystals and promote the growth of equiaxed crystals; when the magnetic flux density is increased, the grain refining effect is better, the solidification rate of 2024 aluminum alloy increases remarkably, and the full solidification time is shorter; the reasons of grain refinement may be that the thermo-electromagnetic convection effect related to Peltier effect is stronger than electromagnetic braking effect, which can enhance the heat transfer and fluid flow in the solidification front, and that undercooling temperature is enlarged.
Abstract: Cloud computing is regarded as one of the most enticing technologies and potential silver bullet in the IT industry. Because of open condition and general-purpose nature of cloud, security issue is becoming a bottle neck of rapid development and broad application of cloud computing. Firstly, this paper addresses cloud customers’ significant concerns about and requirements of cloud security. Secondly, cloud security risks and threats posed by the pervasive and ad hoc nature of the cloud are comprehensively analyzed. Finally, some effective and dependable security mechanisms are proposed to lower cloud security risks and meet security requirements of cloud customers. Especially, a novel scheme for integrity and copyright protection of customers’ works in the cloud is presented based on digital watermarking and digital signature.
Abstract: It’s hard to directly transmit ‘Mechanical Engineering Online Courses’ on the computer network, for there are many diagrams with complex structures and much information capacity. By course systems analysis, course scripts making, multimedia materials production; with choice of database server platform, application technologies like streaming media and dynamic web page technology, image and video processing, the essay makes the online course design more easily and the direct transmission speed on the computer network more quickly, and helps majority of teachers design and develop large-capacity online courses.
Abstract: According to moisture damage phenomenon of hunan province expressway, this study choses Lin-Chang, Lei-Yi, Heng-Zao as research object.The parameters of the pavement, such as void, thickness, asphalt-aggregate ratio and gradation of the asphalt concrete are measured, explored water damaged reasons in hunan specific hot and humid environment and puts forward the prevention countermeasures of asphalt pavement water damage-OGFC.