This paper investigates an adaptive lifting scheme for wavelet-based image compression, which performs update before prediction, and then we proposes an improved adaptive update and prediction scheme to better exploit the correlation among neighboring pixels. Simulation results show that the proposed scheme generates in the transformed domain lower coefficients' entropy, lower high-frequency coefficients' energy and more zero values, which make it useful for image compression applications.
The current structural fire design approaches are developed for fully developed compartment fires, the gas temperatures of which can be approximated as uniformly distributed in the compartment. In localized fires, the gas temperature distributions are spatially nonuniform. Recent numerical studies on the response of steel members subjected to localized fires are presented. Simple models based on plume theory and sophisticated computational fluid dynamics model were used to predict the heat fluxes from localized fires to exposed steel members. Thermomechanical simulations were conducted to predict the temperature and structural responses of the members. The numerical models were validated against standard fire tests and localized fire tests. The lateral torsional buckling behavior of simply supported steel beams, failure behavior of restrained steel beams, and buckling behavior of steel columns in localized fires were predicted and compared with the behaviors in the standard fire. The main finding of these studies was due to temperature gradient, the behavior of steel members in localized fires may be totally different from that in the standard fire, and the failure or buckling temperature of steel members in localized fires may be much lower than that in the standard fire. Structural fire design for steel members based on the standard fire may not be conservative if the potential real fires are localized fires.
The distresses of asphalt pavement, which include fatigue, rutting, and low temperature cracking, are related to the elastic modulus of asphalt concrete (AC). In addition, the elastic modulus of AC is a design variable for asphalt pavement structural design when elastic-layer system theory is employed. However, in the most commonly used AC design methods (the Marshall, Hveem, and Superpave methods), the elastic modulus is not used as a control variable. Therefore, these design methods do not ensure that the desired elastic modulus of AC will be obtained. In this paper, AC is treated as a two-phase composite with aggregates dispersed in the asphalt matrix. Based on this treatment, a two-layer built-in micromechanical model of AC is developed by embedding an asphalt-coated circular aggregate into an equivalent AC medium. Using this model, an equation predicting the elastic modulus of AC is derived. The elastic modulus of AC predicted by the present model is compared with the Hashin and Shtrikman theoretical bounds and the Heukelom and Klomp equation. Using these comparisons, the proposed model is shown to be reasonable and applicable for predicting the elastic modulus of AC. Thus, the existing mix design approaches can be improved by using the modulus prediction model presented in this paper.
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