Approach to minimizing consumption of energy in wireless sensor networks

The Wireless Sensor Networks (WSN) technology has benefited from a central position in the research space of future emerging networks by its diversity of applications fields and also by its optimization techniques of its various constraints, more essentially, the minimization of nodal energy consumption to increase the global network lifetime. To answer this saving energy problem, several solutions have been proposed at the protocol stack level of the WSN. In this paper, after presenting a state of the art of this technology and its conservation energy techniques at the protocol stack level, we were interested in the network layer to propose a routing solution based on a localization aspect that allows the creation of a virtual grid on the coverage area and introduces it to the two most well-known energy efficiency hierarchical routing protocols, LEACH and PEGASIS. This allowed us to minimize the energy consumption and to select the clusters heads in a deterministic way unlike LEACH which is done in a probabilistic way and also to minimize the latency in PEGASIS, by decomposing its chain into several independent chains. The simulation results, under "MATLABR2015b", have shown the efficiency of our approach in terms of overall residual energy and network lifetime

Degradation mechanism analysis in temperature stress tests on III-V ultra-high concentrator solar cells using a 3D distributed model

A temperature stress test was carried out on GaAs single-junction solar cells to analyze the degradation suffered when working at ultra-high concentrations. The acceleration of the degradation was realized at two different temperatures: 130 °C and 150 °C. In both cases, the degradation trend was the same, and only gradual failures were observed. A fit of the dark I–V curve at 25 °C with a 3D distributed model before and after the test was done. The fit with the 3D distributed model revealed degradation at the perimeter because the recombination current in the depletion region of the perimeter increased by about fourfold after the temperature stress test. Therefore, this test did not cause any morphological change in the devices, and although the devices were isolated with silicone, the perimeter region was revealed as the most fragile component of the solar cell. Consequently, the current flowing beneath the busbar favors the progression of defects in the device in the perimeter region

Saturation of THz detection in InGaAs-based HEMTs: a numerical analysis

International audienceBy numerical simulations, we investigate the large-signal photoresponse of InGaAs high electron mobility transistors submitted to THz radiations. The used pseudo-2D hydrodynamic model considers electron density and velocity conservations equations. A third equation is solved, in order to describe average energy conservation or to maintain it constantly equal to its thermal equilibrium value. In both cases, the calculated photoresponse increases with the incoming power density for its smallest values. For the higher values, a saturation of the photoresponse is observed, in agreement with experimental results, only when the energy conservation is accounted for. This allows to relate the limitation of the transistor detection features to electron heating phenomenon

Improvement of FET-based terahertz detectors by phase-controlled current response

International audienc

Analysis of THz detection saturation processes in InGaAs-based HEMTs

International audienc