Advanced Materials Research Vols. 457-458

Abstract: In the paper, the Voronoi tessellation model is used to represent the microstructure of ceramic tool materials. And a finite element model based on cohesive element method has been developed to investigate the fracture behavior of the microstructure. The influences of mesh densities and cohesive parameters on the cracking patterns have been discussed. It is found that the enhancement of the grain boundary strength is beneficial for raising the fracture resistance of single-phase ceramic tool materials.

Abstract: The mechanical properties of car wheel mast have high reliability requirements. The impact test for trial casting aluminum alloy wheel must be passed, which is one of the bench tests. Based the practical case, the integrated finite-element model for virtual test is established, including impact block, wheel, tire, bracket, rubber pad, the standard test load conditions are imposed, and the entire impact process was simulated by finite-element method, the velocity, displacement and kinetic energy curves of the impact block, the stress distribution and the impact force curve of change were obtained. Moreover, using in a typical case, compared with the physical impact test, the model and procedure of the finite-element numerical simulation was verified. The modeling method and calculation procedure given can guide the virtual design of aluminum-alloy wheel, the blindness of design can be reduced, and the development work efficiency can be increased.

Abstract: In this work, a transparent passive DMFC was constructed to investigate the CO₂ bubble behavior in perforated current-collector (PECC) and parallel current-collector (PACC) by using a digital camera. Experiments were carried out in a passive DMFC with active membrane area of 9 cm², working at ambient temperature and pressure. Results showed that small discrete bubbles appeared in PECC at low current densities; while the PECC was predominated by big bubbles at high current densities, which led to deterioration of methanol mass transfer. On the contrary, the PACC was more efficient to remove CO₂ bubbles than the PECC did. Therefore, it gained a better performance at high current densities.

Abstract: With the rapid development and integration of the Internet, wireless communication network and the Internet of Things, the Internet faces many challenges as a bearer network: a large volume of information exchange, multi-level QoS and smoothly switching multiple access protocols. The Internet should be able to provide a variety of network capacity in a more dynamic and on-demand way, not just only limited network resources provision through virtualization. The elastic network is expected to adapt to network changes by enabling network protocols selection and combination dynamically. Cloud computing illustrates a new Internet-based model of IT resources (hardware, software, data) provision, delivery and consumption as a service. Therefore, network protocols as a service can provide guaranteed quality of service and good quality of experience to users who do not care about any network configuration and network management. In this paper, we proposes a novel idea of network capacity on demand by combining the service provision model of cloud computing with the openness of the network protocol. The related conception and stakeholders of network protocol as service are depicted. Cloud-based network architecture is design to present the provision, delivery and consumption of network capacity on demand and discuss the key features of cloud-based network. Finally, a prototype of cloud-based network is implemented by extending OpenFlow architecture.

Abstract: In order to systematically explore the properties of the mesh bumper under hypervelocity impact, the quantitative research of protect characteristics was carried out with the numerical simulation. The experiments, in which the projectile impacted the multi-layers mesh bumper at hypervelocity, were simulated using the Ls-Dyna hydro-codes. The results for simulations and experiments were compared and analyzed. The effectiveness and accuracy of the simulation model is proved. It is shown that the morphologies of debris cloud were obviously varied with the change of impact position.

Abstract: By using the mobile property of silicone oil, a wedged iron (Fe) film system, deposited on glass substrate, has been prepared by dc-magnetron sputtering technique. The wedged Fe film is quenched by the silicone oil during deposition, and therefore contains a very high compressive stress, which is relieved by formation of a large number of telephone cord buckles. Both the buckle width l and maximum buckle deflection δ increase linearly with the film thickness, but the ratio of δ to l (l/δ ) decreases steadily. The internal stress and adhesion energy are estimated in the frame of continuum elastic theory.

Abstract: The residual stress and the effect of microstructure prameters on failure performance of Ni/Ni3Al multi-layered sheet were studied by Correlative theory and FE method. The results showed that the fracture work increases gradually with the increasing of layer number or thickness ratio. However, the rising extent reduced gradually and when the two parameters exceeded a certain value, the fracture work would not be changed. The value of residual stress reached its maximum at the centre and reached its minimum at the edge of multi-layered sheet. Residual stress in Ni layers and Ni3Al layers was compressive stress and tension stress respectively. With increasing of layer number or thickness ratio, compressive stress would rise gradually and compressive stress would reduce gradually.

Abstract: Creep age-forming (CAF) technology is a new forming method, which combined age hardening and creep forming processes into one. It is mainly used to manufacture wing panels. In this paper, a set of experimental device of creep age forming is developed and the influence of process parameters on the springback of artificially aged 2524 aluminium alloys (AA2524) are investigated. The law of the comprehensive effect of aging time, aging temperature, elastic pre-deformation radius and work-piece thickness, on creep aging springback and mechanical properties of AA2524 is obtained. Based on multiple regression analysis, springback prediction model of process parameters is established and further proven experiments have then been carried out. The result shows that the maximum springback deviation between the experimental results and the prediction ones is within 9.5%. The accuracy of springback prediction model is validated, which provides a theoretical basis for process parameter optimization and springback prediction of CAF.

Abstract: A mobile social network plays an essential role as the spread of information and relationship. Mining the popular P2P messages in a short period of time is very valuable. Traditional mining method is not suitable for this very large scale dataset. In this paper, we present a mining approach based on MapReduce parallel framework. We use our metric to analyze point-to-point (p2p) messages within an organization to extract social hierarchy. We analyze the behavior of the communication patterns with taking into account the actual communication messages sent by users. Experimental results show that the final dataset of popular messages is very small with high sending coverage ratio. Empirical studies on a large real-world mobile social network show that performance of our algorithm.

Abstract: Since the "Eleventh Five-Year" plan, the State Grid Corporation of China (SGCC) improves the company’s science and technology innovation capability using UHV technology as leading strategy. This paper summarizes and describes SGCC in technology innovation investment status, technology innovation system and test systems construction, R&D management system construction and technological innovation capacity-building results.