Dynamic Power Dissipation Control Method for Real-Time Processors Based on Hardware Multithreading

In order to eliminate the energy waste caused by the traditional static hardware multithreaded processor used in real-time embedded system working in the low workload situation, the energy efficiency of the hardware multithread is discussed and a novel dynamic multithreaded architecture is proposed. The proposed architecture saves the energy wasted by removing idle threads without manipulation on the original architecture, fulfills a seamless switching mechanism which protects active threads and avoids pipeline stall during power mode switching. The report of an implemented dynamic multithreaded processor with 45 nm process from synthesis tool indicates that the area of dynamic multithreaded architecture is only 2.27% higher than the static one in achieving dynamic power dissipation, and consumes 1.3% more power in the same peak performance.

Hot Deformation Behavior of 2124 Al Alloy

The mechanical behavior of 2124 Al alloy produced by powder metallurgy was investigated with compression test at different temperatures and strain rates. The tests were performed in the temperature range of 300℃～500℃ and at strain rates from 0.001 s^-1 to 1.0 s^-1. The compression flow curves exhibited an initial sharp increase with strain, followed by monotonous hardening. The maximum stress decreased with decreasing strain rate and increasing temperature. The hot deformation characteristics of the material were studied using processing maps. The domain of safety and unsafe regime were identified and validated through microstructural examination.

Characterization of hot deformation behavior of 30Si2MnCrMoVE low-alloying ultra-high-strength steel by constitutive equations and processing maps

Isothermal compression tests of as-forged 30Si2MnCrMoVE low-alloying ultra-high-strength steel were carried out on a Gleeble 3500 thermal simulator at the deformation temperatures of 950-1150℃and strain rates of 0.01-10 s^−1.Based on the classical stress-dislocation density relationship and the kinematics of the dynamic recrystallization,the constitutive equations of the work hardening dynamical recovery period and dynamical recrystallization period were developed by using the work hardening curve and Avrami equation,which shows good agreement with the experimental value.Processing maps at the strain of 0.90 were constructed based on dynamic material model and were analyzed combined with microstructure observation under different conditions.The optimum parameter based on the processing maps was obtained and verified by a supplementary experiment.The power dissipation maps and instability maps at strains of 0.05-0.90 were also constructed,and the evolution law was analyzed in detail.The established constitutive equation and hot processing maps can provide some guidance for hot working process.

Development of Constitutive Equation and Processing Maps for IN706 Alloy

The hot deformation behavior of IN706 has been investigated by means of hot compression tests in the temperature range of 900-1150℃ and strain rate range of 0.001-1 s^-1. The constitutive equation was developed on the basis of experimental data. Power dissipation efficiency （η） and instability parameter （4） maps were evaluated using the principles of the dynamic material model. Furthermore, the EBSD microstructure analysis was performed for validation, revealing that η was closely associated with the mechanism of dynamic recrystallization （DRX）. Microstructure transition map was composed of contour plots of η, 4, and DRX. The DRX domain zones and instable zones were identified in the processing map and were classified based on η. In a view of microstructure refinement and workability improvement, the optimum processing should be selected in the temperature range of 970-1025 ~C and the strain rate range of 0.08-0.01 s^-1.

Technological Aspect of Processing Maps for the AA2099 Alloy

Results of an experimental and modelling study of forming processes in the AA2099 Al–Cu–Li alloy, for a wide range of temperatures, strains and strain rates, are presented. The analyses are based on tensile testing at 20 °C at a strain rate of 0.02 s-1and uniaxial compression testing in the temperature range 400–550 °C at strain rates ranging from0.001 to 100 s-1, for constant values of true strain of 0.5 and 0.9. The stability of plastic deformation and its relationship with a sensitivity of stress to strain rate are considered. The power dissipation efficiency coefficient, g（%）, and the flow instability parameter, n B 0, were determined. The complex processing maps for hot working were determined and quantified, including process frames for basic forging processes： conventional forging and for near-superplastic and isothermal conditions. A significant aspect is the convergence of power dissipation when passing through the 500 °C peak.Deformation, temperature and strain-rate-dependent microstructures at 500 °C for strain rates of 0.1, 1, 10 and 100 s-1are described and analysed for the conventional die forging process frame, corresponding to 465–523 °C and strain rates of50–100 s-1.