It shows better performance in terms of the network lifetime and the dissipated energy than those protocols that apply the same probability to overnight delivery the whole network. However, the work of CODA relies on global information of node position, and thus it is not scalable.Mhatre et al. [7] presented a comparative study of homogeneous and heterogeneous networks in terms of overall cost of the network, defined as the sum of the energy cost and the hardware cost. They analyzed both single-hop and multi-hop networks. They used LEACH as a representative homogeneous, single-hop network, and compared LEACH with a heterogeneous single-hop network. The authors indicate that using single-hop communication between sensor nodes and the cluster head may not be the Inhibitors,Modulators,Libraries best choice when the propagation loss index k for intra-cluster communication is Inhibitors,Modulators,Libraries large (k > 2).
They propose a multi-hop version of the LEACH protocol (M-LEACH) and show the cases in which M-LEACH outperforms the single-hop Inhibitors,Modulators,Libraries version of the protocol.In
Heat fluxes through the terrestrial surface layer are major drivers of climate. For land areas with sparse or no vegetation, the quantities involved in this energy exchange are fundamentally linked with the moisture in the soil surface. Techniques for monitoring the surface moisture on the spatial scales relevant for climate and meteorological research are therefore of particular interest [1�C5].Almost 25 years ago, it was suggested that soil moisture could be retrieved from remotely sensed thermal radiance received with an L-band radiometer [6,7].
Today L-band Inhibitors,Modulators,Libraries radiometry is one of the most promising approaches for remote soil-moisture retrieval since: (i) the atmosphere and clouds are almost transparent, thus allowing for all-weather measurements; (ii) the impact of vegetation canopies and surface roughness is less distinct compared with passive measurements at higher frequencies and active remote sensing techniques (radar); (iii) solar radiation affects radiometer measurements at the L-band only insignificantly, which allows for measurements at any time of the day; (iv) the 1,400?1,427 MHz frequency band is protected, which means that distortions of thermal radiance due to man-made radio frequency interferences (RFI) are minimized. However, in the past years several field experiments performed in Europe have shown that RFI is present even in the protected part of the L-band.
During the calibration and validation Anacetrapib activities associated with ESA��s SMOS mission [8] it turned out that further ground-based passive L-band selleck products experiments would be indispensable for the commissioning and the operative phase of the mission. To address this need, the three identical radiometers ELBARA II depicted in Figure 1 were built by Gamma Remote Sensing (G��mligen, Switzerland) as ordered by the ESTEC, in the framework of the contract ESTEC 21013/07/NL/FF ��L-band Radiometer Systems to be deployed for SMOS Cal/Val Purposes��.Figure 1.