Papers by Keyword: Effective Temperature

Abstract: During high-pressure torsion (HPT), the sample positioned between the plungers of the experimental setup is resistant to fracturing, allowing the HPT process to be sustained almost indefinitely. Despite this, relaxation processes taking place within the sample during HPT lead swiftly to the establishment of a steady state. Factors such as hardness, grain size, the scale of second-phase precipitates, electrical conductivity, lattice spacing, among others, rapidly reach a saturation point, albeit after varying revolutions of the plunger. For instance, in the scenario of HPT involving a binary solid solution accompanied by secondary phase particles that act as sources of dissolved atoms, a dynamic equilibrium and competition emerge between the formation and decomposition of a supersaturated solid solution. Consequently, a specific equilibrium state is achieved with a designated concentration (c_ss) of the second component within the solid solution. This equilibrium state is independent of the initial one (referred to as equifinality). The steady-state concentration c_ss can be identified on the solubility limit line (solvus) of the second component in the phase diagram at an effective temperature T_eff. In copper alloys, the value of T_eff grows as the activation enthalpy for the volume diffusion of the second component increases. This amplification signifies a rise in defect concentration and an activation-driven character of mass transfer during HPT.

Abstract: Severe plastic deformation (SPD) can lead to the phase transformations in the materials. Even the SPD-treatment at ambient temperature T_SPD = 300 K is frequently equivalent to the heat treatment at a certain elevated temperature (effective temperature) T_eff > 300 K. However, if the real annealing at effective temperature leads to the grain growth, SPD leads to strong grain refinement. SPD also accelerates the mass transfer in the materials. In this review the methods of determination for effective temperature after high-pressure torsion of metallic alloys are discussed as well as SPD-driven acceleration of diffusion.

Abstract: —Surface soil moisture is an important parameter in describing the water and energy exchanges at the land surface/atmosphere interface. Passive microwave remote sensors have great potential for monitoring surface soil moisture over land surface. The objective of this study is going to establish a model for estimating the effective temperature of land surface covered with vegetation canopy and to investigate how to compute the microwave radiative brightness temperature of land surface covered with vegetation canopy in considering of the canopy scatter effect.

Abstract: Based on the long-term monitoring data of Donghai Bridge, span length changes of the main channel of the bridge was analyzed from the expansion joint displacement data monitored，and the correlation between the span changes and the environmental factors, which are temperature and wind load, was analyzed. Results show that temperature is the main factor influencing the span change, while the correlation between span changes and wind load is weak so can be ignored. The linear regression model established between span changes and the structure effective temperature can be used to estimate the interval of bridge span changes and examine the correctness of the expansion joint data monitored. Moreover, the regressive model of accumulated expansion joints displacement and time history can provide valuable information for design, maintenance and replacement of the expansion joints.