Advanced Materials Research Vols. 211-212

Abstract: This paper presents a spectral finite element method for a cylindriacl shell with a passive constrained layer damping treatment. A thin shell theory based on Donnell-Mushtari-Vlasov assumption is employed. The equation of spectral unit and the method of determination of natural frequency and modal loss factor are presented.

Abstract: In the paper, the problem of dynamic scheduling with random disturbance is taken into consideration. Through analyzing the workshop disturbance, the processing strategy and simulation procedure is proposed. On this basis, the supervisory control expert system is developed on the platform of G2. The simulation results given at last illustrate the main function of the system, including manufacturing process monitoring, abnormal event warning, and rescheduling.

Abstract: magnesium and magnesium alloys are green engineering materials for 21st century. In the paper, the model of electromagnetic shielding performance of Magnesium is built according to different media around magnesium. If magnesium is plated on engineering plastic board, the simulations show that the property of magnesium to reflect electric-field component is a little better than the property of magnesium to reflect magnetic-field component. Whether magnesium is surrounded with air medium, or magnesium is plated in engineering plastics board, the total shielding effectiveness of magnesium varies with thickness of magnesium and frequency of electromagnetic wave.

Abstract: The finite element analysis is presented in this paper in order to investigate residual stress distribution in the interphase of restoration-tooth structure due to polymerization shrinkage of resin-based composite. The restoration-tooth interface is simulated using plane elements of varying material properties and thicknesses. The stress within restored-tooth structure built-up from the polymerization shrinkage of the restorative composite were computed accounting for the time-dependent, visco-elastic behaviour of the composite. A sensitivity study is performed to examine the relative influence of geometric and material parameters of interphase on the shrinkage stress development. It was found that a correlation exists between material and geometry properties at the restoration-tooth interface and higher shrinkage stresses on interphase due to polymerization shrinkage. The development trend of residual stress from polymerization shrinkage in the restored-tooth structure was discussed and forecasted. The varying material and geometry properties of restoration-tooth interface seem to have conclusive effect on the interfacial stress system, as well as on the longevity of the restoration. From the purely mechanical point of view, this can result in interfacial debonding.

Abstract: The steering radius and the vehicle velocity is utilized to control the drive force and steering angle of each electric-wheel in this essay. In order to improve the characteristics of vehicle, a dynamic simulation was made with the predictions of constant velocity and radius to the vehicle model with the R-v control strategy. This simulation proves that the characteristics of vehicle steering will be better with the utilization of this control strategy.

Abstract: To solve the classical uncapacitated multiple allocation p-hub median problem, (UMpHMP), this paper establishes the evaluation System of hub-index by making use of the rough set data mining technology to reduce the range of hub choice from n alternative hubs to the limited q(q<n) airports, which greatly reduces the variables and constraints of the UMpHMP model. To solve the NP-hard problems, the genetic algorithm was designed according to the improved model for solutions. The simulation example of domestic 15 cities the route network designing indicates that the new model can reduce the solution complexity and increase the efficiency.

Abstract: As XPath is the core of most XML query languages, the efficiency of processing XPath expression has been a main part of the cost in XML queries. However, most existing XPath processing algorithms, which don't take index structure into account, spend lots of costs on spaces and time. This paper proposes an efficient XPath query processing mechanism based on structural index that makes full use of XML structural index to quickly retrieve XML data. Coming together with the mechanism, the Compressed XPath Query Tree based on structural index is proposed, which significantly reduces many join operations. Then query algorithms are used to deal with all the structural relationship using our mechanism. Finally, experiments will run the algorithm on real XML datasets and query workloads to report the performance of our mechanism and show the efficiency compared with other mechanisms.

Abstract: A small polishing robot must be made to adapt the change of curvature and slope of the cutting curved surfaces when it moves on the large curved surface. This paper develops a small moving robot to move on the large curved surface and polish it which can adapt the change of curvature and slope of the cutting curved surfaces. It also establishes the kinematics model and the inverse kinematics for movement control of the robot. By analyzing the motion characteristics and the processing of automatic polishing, the paper develops the posture equation of the robot. Experiments shows the small moving robot is capable of adaptability in polishing curved surfaces.

Abstract: In this paper, an adaptive feedback control method is proposed for the anti-control of chaos of single time scale brushless DC motor system with unknown parameters based on model-matching. The well-known Rössler chaotic system is considered as the reference system. The chaotification is achieved choosing an appropriate control law and a parametric updating law using Lyapunov stability theory, which provides the stability of the resulting adaptive system and the convergence of the tracking errors to zero. The numerical simulation results show the effectiveness of the proposed method.

Abstract: With the development of Micro-electro-mechanical systems (MEMS) and Nano-electro-mechanical systems (NEMS), dimension of their parts is required to nanometer scale, and the characteristics of machined-surface of nano-scale parts affect strongly its application. Surface relaxation plays an important role to the characteristics of the machined-surface. In this paper, machined-surface of monocrystal copper used as the specimen of surface relaxation, and its surface relaxation process is simulated. The influences of surface relaxation on surface energy, atom array, surface roughness, surfaces hardness and surface residual stress of the monocrystal copper are analyzed. Results show that surface energy and surface hardness decrease due to relaxation; work-hardening can’t be completely eliminated by the relaxation; compression residual stress of the machined surface is changed gradually to tensile stress during the relaxation. These research results are very helpful to the application of nano-machined parts.