In this study, isothermal torsion tests were carried out on magnesium AZ31B alloy under constant strain rate conditions, in the range of 250 to 400oC at 0.01, 0.1, and 1.0 s-1. Alloy flow stress dependence on strain rate and temperature can be described by a power law with activation energy of 130 kJ/mol. Microstructural examination of hot deformed samples shows very fine recrystallized grains decorating grain boundaries of larger gains in the form of a necklace. These fine grains are produced by dynamic recrystallization at the grain boundaries of original grains. Microstructure evolution, based on samples quenched at different strain levels, indicates that increasing deformation strain has little effect on recrystallized grain size but widens the recrystallized region, with full recrystallization achieved at a certain high strain level. Recrystallized grain size increases with increasing deformation temperature and strain rate. The latter suggests recrystallization in AZ31 to be essentially a time dependant phenomenon.

To make steel exhibit attractive properties as high strength and good ductility, this paper presents a novel one step method for forming-Q&P integration—Hot Stamping-Dynamic Partitioning (HS-DP) process. The proposed HS-DP process is simulated with salt bath heat treatment. The effect of microstructure and mechanical properties in a low-carbon AHSS with different cooling rate of the new process is investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and tensile test methods. Microstructure of the steel subjected to HS-DP treatment is mainly composed of initial quenched martensite phase , final quenched martensite phase and retained austenite phase formed. The impact of retained austenite is also discussed, especially the influence of elongation caused by various retained austenite volume fraction and carbon-content. This experiment illustrates the promising application potential of the hot stamping-dynamic carbon partitioning process.

The model of cellular automaton (CA) for simulating the martensitic transformation of the high strength and elongation steel during quenching was established. The microstructure evolution of martensitic transformation of high strength and elongation steel during continuous cooling was simulated dynamically, in terms of parameters such as the volume fraction and morphology of the martensite and retained austenite were quantitatively, accurately and visually described. The simulation results could provide a theoretical reference for the control of the microstructure and property of high strength and elongation steel.

MANETs become a considerable interest nowadays. However, these types of networks are vulnerable to a large group of attacks, e.g., MAC layer attacks. Most of the previous researches related to security issues focus on detection of misbehaviors after it occurred. We propose a new way of thinking to evade occurrence of misbehaviors. A novel clustering algorithm is presented using analytic hierarchy process to elect clusterhead. Afterwards, the clusterhead is required to assign backoff values to originators in its transmission range, which are also the members in the corresponding cluster, rather than permitting the originators to choose backoff values. Meanwhile, the elected clusterhead also monitors whether originators obey the backoff values. With the proposed scheme, the misuse of the backoff in MAC layer in 802.11 DCF can be prevented.

Combining with compression strength and tensile strength, the cohesive strength method is applied to determine the asphalt content (by weight of aggregate) of asphalt treated base (ATB) for the purpose meeting ATB tensile performance. The results are compared with those of Marshall Method. Two calculation methods of asphalt film thickness are applied to calculate the thickness of asphalt film. The calculation results show that cohesive strength method force the admixture to attain the better thickness of asphalt film, and the spectrum of film thickness is between about 6.5μm ~9.0μm.