Decomposition Kinetics and Cook-Off Numerical Simulation of Insensitive Energetic Plasticizer Plasticized Propellants

Aiming at the thermal safety issues between the insensitive energetic plasticizer and propellant components, NG/BTTN and insensitive energetic plasticizer BuNENA plasticized propellant was compared by DSC test and cook-off numerical simulation, with the thermal safety property evaluated. The decomposition activation energy Ea and self-ignition temperature Tb of BuNENA plasticized propellant was lower than that of NG/BTTN plasticized propellant. Two kinds of propellant responded in the central area during slow cook-off simulation while in the near shell area during medium cook-off simulation. During fast cook-off simulation, depending on the different thickness of insulator, propellant responded at the area near shell or the area near the caps. The response temperature of two propellants in cook-off simulation agreed with decomposition and self-ignition temperature by DSC, and the decomposition of plasticizer could trigger the response. In cook-off simulation, BuNENA plasticized propellant showed a lower response temperature with a smaller high temperature area before response, resulting a milder response and better thermal safety than NG/BTTN plasticized propellant.

Prepare: P owe r -Awar e A p proximate Re a l-time Task Scheduling for Ene r gy-Adaptiv e QoS Maximization

Achieving high result-accuracy in approximate computing (AC) based real-time applications without violating power constraints of the underlying hardware is a challenging problem. Execution of such AC real-time tasks can be divided into the execution of the mandatory part to obtain a result of acceptable quality, followed by a partial/complete execution of the optional part to improve accuracy of the initially obtained result within the given time-limit. However, enhancing result-accuracy at the cost of increased execution length might lead to deadline violations with higher energy usage. We propose Prepare , a novel hybrid offline-online approximate real-time task-scheduling approach, that first schedules AC-based tasks and determines operational processing speeds for each individual task constrained by system-wide power limit, deadline, and task-dependency. At runtime, by employing fine-grained DVFS, the energy-adaptive processing speed governing mechanism of Prepare reduces processing speed during each last level cache miss induced stall and scales up the processing speed once the stall finishes to a higher value than the predetermined one. To ensure on-chip thermal safety, this higher processing speed is maintained only for a short time-span after each stall, however, this reduces execution times of the individual task and generates slacks. Prepare exploits the slacks either to enhance result-accuracy of the tasks, or to improve thermal and energy efficiency of the underlying hardware, or both. With a 70 - 80% workload, Prepare offers 75% result-accuracy with its constrained scheduling, which is enhanced by 5.3% for our benchmark based evaluation of the online energy-adaptive mechanism on a 4-core based homogeneous chip multi-processor, while meeting the deadline constraint. Overall, while maintaining runtime thermal safety, Prepare reduces peak temperature by up to 8.6 °C for our baseline system. Our empirical evaluation shows that constrained scheduling of Prepare outperforms a state-of-the-art scheduling policy, whereas our runtime energy-adaptive mechanism surpasses two current DVFS based thermal management techniques.

The Thermal Biology of Takydromus kuehnei Indicates Tropical Lizards From High Elevation Have Not Been Severely Threatened by Climate Change

Climate change poses different threats to animals across latitudes. Tropical species have been proposed to be more vulnerable to climate change. However, the responses of animals from tropical mountains to thermal variation and climate change have been scarcely studied. Here, we investigated the thermal biology traits of a tropical lizard (Takydromus kuehnei) distributed at high elevations (>950 m) and evaluated the vulnerabilities of T. kuehnei by thermal biology traits, thermal safety margin, and thermoregulatory effectiveness. The average active body temperatures of T. kuehnei in the field were 26.28°C and 30.65°C in April and June, respectively. The selected body temperature was 33.23°C, and the optimal temperature for locomotion was 30.60°C. The critical thermal minimum and critical thermal maximum temperatures were 4.79°C and 43.37°C, respectively. Accordingly, the thermal safety margin (1.23°C) and thermoregulatory effectiveness (1.23°C) predicted that T. kuehnei distributed in tropical mountains were not significantly depressed by environmental temperatures. This study implies that high-elevation species in tropical regions may not be severely threatened by ongoing climate change and highlights the importance of thermal biology traits in evaluating the vulnerability of species to climate change.