Key Engineering Materials Vols. 474-476

Abstract: Based on the plastic bending theory, the influence of material properties fluctuations of pipeline steel on the air bending is discussed by the computer simulation technology and design of the orthogonal was adopted to define scientific simulation experiment scheme. Among the material properties, initial yield strength is the most critical issue. The relation of the initial yield strength, the key process parameter, punch penetration, and the tube forming quality was studied and the variation of bending angle after springback and forming force with the punch insertion was analyzed. The parameters prediction model, which was established by using RBF network technology, is proved rational and precise since the error between predicting results and simulation value is very small. The method can be used to optimize the relevant process parameters and to design the reasonable process scheme.

Abstract: To set-up a rate-dependent dynamic hysteresis model, eddy current loss in giant magnetostrictive material is represented by the loss in eddy current impedance. By combining static Jiles-Atherton hysteresis model, the equivalent circuit of giant magnetostrictive material is built, the relationship between eddy current impedance and magnetic field and magnetization is derived and the maximum eddy current impedance of the material is clculated. Effective magnetic permeability is applied to estimate the eddy current impedance as exciting rate or frequency gets high. Simulation and experiment results of exciting frequencies at 5Hz,10Hz,20Hz, are compared, showing experiment results are coincident with simulation ones, in term of magnitude order and tilt direction. It is demonstrated that effective permeability is feasible for eddy current impedance estimation and eddy current impedance-based dynamic Jiles-Atherton hysteresis model is able to reflect practical dynamic hysteresis.

Abstract: The structure of virtual assembly environment and the pattern of response message was represented based on the Multi-Agent theory; the context perception mechanism in virtual assembly environment was analyzed, and a perception algorithm was put forward. The result showed that cognitive burden of human had been shared by virtual assembly environment in reason; the efficiency of assembly manipulation in virtual assembly environment had been increased; the level of human-computer interaction had been improved.

Abstract: Large slewing bearing is a special kind of rolling bearing with heavy load and very low rotation speed. It is important to carry out faults monitoring on this kind of rolling bearing. However, it is difficult to carry out vibration monitoring on such large slewing bearing. The running conditions of slewing bearings of ship loader and stacking crane in Qinghuangdao Port were analyzed using ferrography and spectrometric analysis technology. Monitoring results showed that the slewing bearing of SL-Q1 ship loader was under abnormal wear condition. Further inspection indicated that the rolling elements of this bearing underwent severe wear and broke down. This suggested that it was feasible to evaluating the wear conditions of this type of large low-speed heavy-load rolling bearing using ferrography and spectrometric analysis.

Abstract: The geometrical structures, the electronic structures, and the NH₃ adsorption properties of pure and B-doped graphene have been investigated using density-functional theory. The density of states (DOS) of pure and B-doped graphene, the adsorption configurations and the adsorption energies of NH₃ adsorbed on pure and B-doped graphene, and the charge transfer between NH₃ and B-doped graphene have been calculated in details. The results indicate that boron doping can enhance the DOS at the Fermi level and slightly enhance the physical adsorption of NH₃ on the surface of graphene. Furthermore, the doping of boron can result in the charge redistribution of graphene, which can induce the charge transfer between NH₃ and graphene and change the transport properties of graphene.

Abstract: In order to make a good decision in the projection investment, and the application of the projection pursuit model of particle swarm algorithm on the investment decision was studied in depth. Firstly, the development of the projection pursuit model of particle swarm algorithm was introduced, and then the brief introduction of PP and the step of constructing the PPC model were introduced. The basic theory and calculating procession of particle swarm algorithm was analyzed. And then the projection investment decision model was established. Finally a case study was carried out and the results showed that this method was simple and effective.

Abstract: Cross-domain authentication is a key technology used in distributed computing, however, it isn’t perfect. In this paper, a new type of hybrid cross-domain authentication model is proposed to make up its shortcoming in safety, scalability and password synchronization. In this model, advantages of Kerberos and SAML in cross-domain authentication process are combined, and it mixed password transport protocols is adopted to achieve password synchronization. Theoretical analysis shows it can enhance the security and scalability of cross-domain authentication, the efficiency of cross-domain authentication is also improved as the attainment of password synchronization.

Abstract: In order to change the current status that machine condition monitoring system is only generally applied to key equipments of large-scaled and high-end business, a low-cost mini condition monitoring system of rotating machinery based on LabVIEW is proposed and designed in this paper. The system is not only of advantages of lower cost, stronger expandability and higher applicability, but also changes the condition that current systems emphasize too much on the comprehensiveness, universality and complexity. It is capable of meeting the wide range of condition monitoring of common rotating machinery, for faults diagnosis and predictive maintenance needs better, then, its potential application can be foreseen.

Abstract: Single-angle compression members with an eccentric load at one end were widely used in transmission towers, analyzing the stability bearing capacity become a very complex issue due to end restraint conditions and the impact of defects. Experiment method and analytical method were used to study the size of the stability capacity on four kinds of members, analytical method use energy relationship, the boundary conditions issue is simplified according to different end restraint capacity, and finally discuss the theoretical ultimate bearing capacity of the test members. Compared with the experimental results show that the elastic theory analytical solution overestimates the capacity of members, using experiment method can obtain more secure mechanical behavior of high-strength angle steel member with an eccentric load at one end.

Abstract: As one kind of oil expellant in improving the recovery ration of oil reservoir (EOR), CO₂ flooding has merits such as extensive adaptability, low cost, high recoverability, and it will become one main way of EOR in future. In this paper, the EOR mechanism of CO₂ flooding has been studied correspond to the geologic conditions in Shengli oil field, which includes three parts: mechanism of expansion, mechanism of reduce oil viscosity and displacement experiment of long core model. Moreover, the detailed process of the test block description of CO₂ flooding in Shengli oil field has been set forth. Through the application in Shengli oil field proves that the EOR mechanism of CO₂ flooding is right and suits for geologic conditions in Shengli oil field.