Polytechnic University of Milan

About: Polytechnic University of Milan is a education organization based out in Milan, Italy. It is known for research contribution in the topics: Computer science & Finite element method. The organization has 18231 authors who have published 58416 publications receiving 1229711 citations. The organization is also known as: PoliMi & L-NESS.

Energy comparison of MPPT techniques for PV Systems

Abstract: Many maximum power point tracking techniques for photovoltaic systems have been developed to maximize the produced energy and a lot of these are well established in the literature. These techniques vary in many aspects as: simplicity, convergence speed, digital or analogical implementation, sensors required, cost, range of effectiveness, and in other aspects. This paper presents a comparative study of ten widely-adopted MPPT algorithms; their performance is evaluated on the energy point of view, by using the simulation tool Simulink®, considering different solar irradiance variations. Key-Words: - Maximum power point (MPP), maximum power point tracking (MPPT), photovoltaic (PV), comparative study, PV Converter.

Dynamics of Slow-Moving Landslides from Permanent Scatterer Analysis

Abstract: High-resolution interferometric synthetic aperture radar (InSAR) permanent scatterer data allow us to resolve the rates and variations in the rates of slow-moving landslides. Satellite-to-ground distances (range changes) on landslides increase at rates of 5 to 7 millimeters per year, indicating average downslope sliding velocities from 27 to 38 millimeters per year. Time-series analysis shows that displacement occurs mainly during the high-precipitation season; during the 1997-1998 El Nino event, rates of range change increased to as much as 11 millimeters per year. The observed nonlinear relationship of creep and precipitation rates suggests that increased pore fluid pressures within the shallow subsurface may initiate and accelerate these features. Changes in the slope of a hill resulting from increases in the pore pressure and lithostatic stress gradients may then lead to landslides.

Iodine chemistry determines the defect tolerance of lead-halide perovskites

Abstract: Metal-halide perovskites are outstanding materials for photovoltaics Their long carrier lifetimes and diffusion lengths favor efficient charge collection, leading to efficiencies competing with established photovoltaics These observations suggest an apparently low density of traps in the prototype methylammonium lead iodide (MAPbI3) contrary to the expected high defect density of a low-temperature, solution-processed material Combining first-principles calculations and spectroscopic measurements we identify less abundant iodine defects as the source of photochemically active deep electron and hole traps in MAPbI3 The peculiar iodine redox chemistry leads, however, to kinetic deactivation of filled electron traps, leaving only short-living hole traps as potentially harmful defects Under mild oxidizing conditions the amphoteric hole traps can be converted into kinetically inactive electron traps, providing a rationale for the defect tolerance of metal-halide perovskites Bromine and chlorine doping of MAPbI3 also inactivate hole traps, possibly explaining the superior optoelectronic properties of mixed-halide perovskites