988 research outputs found

    Mini-uav remote control: a case study at Politecnico di Torino

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    Recent development of modern micro and nano technologies allows aerospace vehicles extremely small size to be constructed. Wide availability and mass production of small dimension components drastically reduce the price of such vehicles. This fact allows them to be constructed by Universities and it makes them useful for education. The Aerospace Systems Engineering Research Group (ASSET) at Politecnico di Torino the design, development and testing small, but quite complex, integrated systems. The goal of this paper is to present one of the contemporary works of this group: the Mini-UAV "ASSET" remote control/flight simulator site. This paper contains a short presentation of the Mini-UAV, a description of its onboard and ground systems and the use of COTS components. The paper explains how the ground control site has also been designed to run as a flight simulator. For this purpose MICROSOFT FLIGHT SIMULATOR for 3D scenario visualization and Matlab/Simulink for airplane and environmental modeling has been used and integrated. In the system are included possibilities of ALTIA Design software exploitation for avionic display visualization. In particular some new modes for HUD, conceived and simulated, are presented and discussed in the paper. The hardware configuration of the Remote Control System/Flight Simulator is briefly described

    Cascade kinetics in an enzyme-loaded aqueous two-phase system

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    Macromolecular crowding plays a critical role in the kinetics of enzymatic reactions. Dynamic compartmentalization of biological components in living cells due to liquid–liquid phase separation represents an important cell regulatory mechanism that can increase enzyme concentration locally and influence the diffusion of substrates. In the present study, we probed partitioning of two enzymes (horseradish-peroxidase and urate-oxidase) in a poly(ethylene glycol)–dextran aqueous two-phase system (ATPS) as a function of salt concentration and ion position in the Hofmeister series. Moreover, we investigated enzymatic cascade reactions and their kinetics within the ATPS, which revealed a strong influence of the ion hydration stemming from the background electrolyte on the partitioning coefficients of proteins following the Hofmeister series. As a result, we were able to realize cross-partitioning of two enzymes because of different protein net charges at a chosen pH. Our study reveals a strong dependency of the enzyme activity on the substrate type and crowding agent interaction on the final kinetics of enzymatic reactions in the ATPS and therefore provides substantial implications en route toward dynamic regulation of reactivity in synthetic protocells

    Pd/C catalysts based on synthetic carbons with bi- and tri-modal pore-size distribution: applications in flow chemistry

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    Two new types of phenolic resin-derived synthetic carbons with bi-modal and tri-modal pore-size distributions were used as supports for Pd catalysts. The catalysts were tested in chemoselective hydrogenation and hydrodehalogenation reactions in a compact multichannel flow reactor. Bi-modal and tri-modal micro-mesoporous structures of the synthetic carbons were characterised by N2 adsorption. HR-TEM, PXRD and XPS analyses were performed for characterising the synthesised catalysts. N2 adsorption revealed that tri-modal synthetic carbon possesses a well-developed hierarchical mesoporous structure (with 6.5 nm and 42 nm pores), contributing to a larger mesopore volume than the bi-modal carbon (1.57 cm3 g–1 versus 1.23 cm3 g–1). It was found that the tri-modal carbon promotes a better size distribution of Pd nanoparticles than the bi-modal carbon due to presence of hierarchical mesopore limitting the growth of Pd nanoparticles. For all the model reactions investigated, the Pd catalyst based on tri-modal synthetic carbon (Pd/triC) show high activity as well as high stability and reproducibility. The trend in reactivities of different functional groups over the Pd/triC catalyst follows a general order alkyne >> nitro > bromo >> aldehyde.Financial support from the Engineering and Physical Sciences Research Council (Engineering Functional Materials, EP/C519736/1), the Overseas Research Students Awards Scheme and the University of Bath Research Studentship is gratefully acknowledged. The assistance of Dr Martin Jennings Dr. Chris Muryn (School of Chemistry, The University of Manchester) on ICP-OES and XPS analyses is acknowledged. KW acknowledges the Royal Society for the award of an Industry Fellowship.This is the author accepted manuscript. The final version is available from RSC via http://dx.doi.org/10.1039/C5CY01401

    Pd/C catalysts based on synthetic carbons with bi- and tri-modal pore-size distribution: Applications in flow chemistry

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    Synthetic carbons with hierarchical mesopores are promising for developing new catalysts for intensified continuous-flow catalysis in structured reactors.Financial support from the Engineering and Physical Sciences Research Council (Engineering Functional Materials, EP/C519736/1), the Overseas Research Students Awards Scheme and the University of Bath Research Studentship is gratefully acknowledged. The assistance of Dr Martin Jennings Dr. Chris Muryn (School of Chemistry, The University of Manchester) on ICP-OES and XPS analyses is acknowledged. KW acknowledges the Royal Society for the award of an Industry Fellowship.This is the author accepted manuscript. The final version is available from RSC via http://dx.doi.org/10.1039/C5CY01401

    Simulation of optical spectra of novel Tl 4 CdI 6 and Tl 4 HgI 6 optoelectronic crystals

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    The results of calculations using local density approximation and generalized gradient approximation: the total energy depending on the volume of the unit cell, the distribution of the total density of states and the partial contributions of electronic orbitals in the band structure of Tl 4 CdI 6 and Tl 4 HgI 6 crystals are shown in this paper. The spectra of the real part of the dielectric permittivity, the spectra of the imaginary part of permittivity, the reflection spectra and the absorption coefficient of both crystals are obtained using the Kramers-Kronig method. A comparative analysis of theoretical calculations with experimental data is carried out. Substantial influence of electron-phonon broadening is shown

    Bi12Rh3Cu2I5: A 3D Weak Topological Insulator with Monolayer Spacers and Independent Transport Channels

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    Topological insulators (TIs) are semiconductors with protected electronic surface states that allow dissipation-free transport. TIs are envisioned as ideal materials for spintronics and quantum computing. In Bi14Rh3I9, the first weak 3D TI, topology presumably arises from stacking of the intermetallic [(Bi4Rh)3I]2+ layers, which are predicted to be 2D TIs and to possess protected edge-states, separated by topologically trivial [Bi2I8]2− octahedra chains. In the new layered salt Bi12Rh3Cu2I5, the same intermetallic layers are separated by planar, i.e., only one atom thick, [Cu2I4]2− anions. Density functional theory (DFT)-based calculations show that the compound is a weak 3D TI, characterized by (Formula presented.), and that the topological gap is generated by strong spin–orbit coupling (E g,calc. ∼ 10 meV). According to a bonding analysis, the copper cations prevent strong coupling between the TI layers. The calculated surface spectral function for a finite-slab geometry shows distinct characteristics for the two terminations of the main crystal faces ⟨001⟩, viz., [(Bi4Rh)3I]2+ and [Cu2I4]2−. Photoelectron spectroscopy data confirm the calculated band structure. In situ four-point probe measurements indicate a highly anisotropic bulk semiconductor (E g,exp. = 28 meV) with path-independent metallic conductivity restricted to the surface as well as temperature-independent conductivity below 60 K

    Twist angle dependent interlayer transfer of valley polarization from excitons to free charge carriers in WSe2/MoSe2 heterobilayers

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    Transition metal dichalcogenides (TMDs) have attracted much attention in the fields of valley- and spintronics due to their property of forming valley-polarized excitons when illuminated by circularly polarized light. In TMD-heterostructures it was shown that these electron-hole pairs can scatter into valley-polarized interlayer exciton states, which exhibit long lifetimes and a twist-angle dependence. However, the question how to create a valley polarization of free charge carriers in these heterostructures after a valley selective optical excitation is unexplored, despite its relevance for opto-electronic devices. Here, we identify an interlayer transfer mechanism in twisted WSe2/MoSe2 heterobilayers that transfers the valley polarization from excitons in WSe2 to free charge carriers in MoSe2 with valley lifetimes of up to 12 ns. This mechanism is most efficient at large twist angles, whereas the valley lifetimes of free charge carriers are surprisingly short for small twist angles, despite the occurrence of interlayer excitons

    Search for the eta-mesic 4He with WASA-at-COSY detector

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    An exclusive measurement of the excitation function for the dd->3Heppi- reaction was performed at the Cooler Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c crossing the kinematic threshold for the eta meson production in the dd->4He-eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the 4He-eta system varied from -51.4MeV to 22MeV. The integrated luminosity in the experiment was determined using the dd->3Hen reaction. The shape of the excitation function for the dd->3Heppi- was examined. No signal of the 4He-eta bound state was observed. An upper limit for the cross-section for the bound state formation and decay in the process dd->(4He-eta)bound->3Heppi- was determined on the 90% confidence level and it varies from 20nb to 27nb for the bound state width ranging from 5MeV to 35MeV, respectively.Comment: 8 pages, 9 figure
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