Relative Greenness Index for assessing curing of grassland fuel

Knowledge of the proportion of live and dead herbaceous fuel in grasslands is important in determining fire danger. This paper examines the Relative Greenness approach for quantifying these live and dead proportions. Relative Greenness places the Normalized Difference Vegetation Index (NDVI) in the context of a time series of measurements. The parameters used to describe the temporal distribution of NDVI and the time interval over which this distribution is assessed impact Relative Greenness and the inferred characteristics of the vegetation. In this paper, the Relative Greenness approach was investigated using different NDVI distribution parameters derived from eight-day composites of surface reflectance from the Moderate Resolution Imaging Spectroradiometer (MODIS). We assessed the accuracy of Relative Greenness for predicting the degree of curing (equivalent to the dead proportion of herbaceous fuel) measured at 25 grassland sites in Australia from 2005 to 2009. Results showed that Relative Greenness explained a greater proportion of the variance and provided a more accurate estimate of the degree of curing than linear regression against NDVI Relative Greenness was further improved using alternative parameters of the NDVI distribution and by selecting an appropriate time interval over which this distribution was assessed

Thermodynamics and Thermoelectricity

Thermoelectric (TE) effects result from the interference of electrical current and heat flow in various materials. This chapter presents a retrospective view on some of the milestones in the development of thermoelectricity. It reviews the thermodynamic theory of galvano- and thermomagnetic effects. As for TE materials, the galvano- and thermomagnetic effects can be found to be more pronounced in semiconductor materials. The chapter considers a basic thermodynamic system and thermodynamics of the ideal Fermi gas. Classical thermodynamics, which is useful for describing equilibrium states, provides very incomplete information on the actual physical phenomena, which are characterized by irreversibility and nonequilibrium states. Since the TE process implies the coupling of the heat flux and electric current, these two fluxes should be driven optimally. They derived two key parameters of the compatibility approach, the relative current and the TE potential