Preliminary design, modeling and control of a fully actuated quadrotor UAV

In this paper a preliminary study on a new concept of fully actuated Unmanned Aerial Vehicle (UAV), named ODQuad (OmniDirectional Quadrotor), is presented. By exploiting two additional actuators, the designed UAV can simultaneously modify the tilting angle of all the propellers, in such a way to decouple position and attitude motions. This solution, differently from other fully actuated UAVs with tilted propellers, avoids internal forces and energy dissipation, due to non-parallel propellers’ axes. A preliminary mechanical design and the kinematic and dynamic models are developed. Moreover, a motion control scheme, based on a hierarchical two loop, has been designed. Simulations are provided in order to show the feasibility of the concept and the effectiveness of the control scheme

Negative charge trapping effects in Al2O3 films grown by atomic layer deposition onto thermally oxidized 4H-SiC

This letter reports on the negative charge trapping in Al2O3 thin films grown by atomic layer deposition onto oxidized silicon carbide (4H-SiC). The films exhibited a permittivity of 8.4, a breakdown field of 9.2 MV/cm and small hysteresis under moderate bias cycles. However, severe electron trapping inside the Al2O3 film (1 × 1012 cm−2) occurs upon high positive bias stress (>10V). Capacitance-voltage measurements at different temperatures and stress conditions have been used to determine an activation energy of 0.1eV. The results provide indications on the possible nature of the trapping defects and, hence, on the strategies to improve this technology for 4H-SiC devices

Recent Advances in Seeded and Seed-Layer-Free Atomic Layer Deposition of High-K Dielectrics on Graphene for Electronics

Graphene (Gr) with its distinctive features is the most studied two-dimensional (2D) material for the new generation of high frequency and optoelectronic devices. In this context, the Atomic Layer Deposition (ALD) of ultra-thin high-k insulators on Gr is essential for the implementation of many electronic devices. However, the lack of out-of-plane bonds in the sp2 lattice of Gr typically hinders the direct ALD growth on its surface. To date, several pre-functionalization and/or seed-layer deposition processes have been explored, to promote the ALD nucleation on Gr. The main challenge of these approaches is achieving ultra-thin insulators with nearly ideal dielectric properties (permittivity, breakdown field), while preserving the structural and electronic properties of Gr. This paper will review recent developments of ALD of high k-dielectrics, in particular Al2O3, on Gr with "in-situ" seed-layer approaches. Furthermore, recent reports on seed-layer-free ALD onto epitaxial Gr on SiC and onto Gr grown by chemical vapor deposition (CVD) on metals will be presented, discussing the role played by Gr interaction with the underlying substrates

Tectonic evolution of the Sicilian Thrust System (central Mediterranean)

The Sicilian Thrust System (STS) is a south-verging (Africa-verging) fold-and-thrust belt including a Mesozoic-Paleogene sedimentary sequence. This thrust stack owes its origin to the deformation of pre-orogenic strata deposited in different palaeogeographic domains belonging to passive margins of the African plate. The STS was deformed during the Neogene, following the closure of the Tethys Ocean and the continental collision between the Sardo-Corso Block and the North Africa margins. The thrust pile was detached from the underlying basement during the Miocene-Pleistocene. The regional-scale structural setting recognized allows us to reconstruct the tectonic evolution of the STS as follows: I - piggy-back thrusting from the Late Oligocene to the Langhian, inducing the building of the Inner Sicilian Chain (ISC); II - piggy-back thrusting from the Langhian to the Tortonian, inducing the formation of the Middle Sicilian Chain (MSC); III - generalized extensional deformation in the chain-foredeep-foreland system from the Tortonian to the Early Pliocene; IV - a new onset of piggy-back thrusting after the Early Pliocene allowed the building of the Outer Sicilian Chain and out-of sequence thrusting in the previously developed ISC and MSC

Correlating electron trapping and structural defects in Al2O3 thin films deposited by plasma enhanced atomic layer deposition

In this article, electron trapping in aluminum oxide (Al2O3) thin films grown by plasma enhanced atomic layer deposition on AlGaN/GaN heterostructures has been studied and a correlation with the presence of oxygen defects in the film has been provided. Capacitance–voltage measurements revealed the occurrence of a negative charge trapping effect upon bias stress, able to fill an amount of charge traps in the bulk Al2O3 in the order of 5 × 1012 cm−2. A structural analysis based on electron energy-loss spectroscopy demonstrated the presence of low-coordinated Al cations in the Al2O3 film, which is an indication of oxygen vacancies, and can explain the electrical behavior of the film. These charge trapping effects were used for achieving thermally stable (up to 100 °C) enhancement mode operation in AlGaN/GaN transistors, by controlling the two-dimensional electron gas depletion

Nanoscale electro-structural characterisation of ohmic contacts formed on p-type implanted 4H-SiC

This work reports a nanoscale electro-structural characterisation of Ti/Al ohmic contacts formed on p-type Al-implanted silicon carbide (4H-SiC). The morphological and the electrical properties of the Al-implanted layer, annealed at 1700°C with or without a protective capping layer, and of the ohmic contacts were studied using atomic force microscopy [AFM], transmission line model measurements and local current measurements performed with conductive AFM

Role of the ENPP1 K121Q Polymorphism in Glucose Homeostasis

OBJECTIVE— To study the role of the ENPP1 Q121 variant on glucose homeostasis in whites from Italy