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Parini A.,Mist Technologies | Parini A.,University of Ferrara | Calo G.,Polytechnic of Bari | Bellanca G.,University of Ferrara | Petruzzelli V.,Polytechnic of Bari
Optical and Quantum Electronics | Year: 2014

This paper presents two different approaches that may allow the optical interconnection between superposed levels of multilayer photonic circuits as, for example, in optical-networks-on-chip. The first configuration is based on multi-mode interference devices, while the second one exploits multiple stacked directional couplers. The issues concerning the analytical and numerical design of such devices are discussed, together with a performance analysis in terms of efficiency and footprint. © 2013 Springer Science+Business Media New York. Source

Fichtner T.,Max Planck Institute for Chemical Physics of Solids | Wang C.,Max Planck Institute for Chemical Physics of Solids | Levin A.A.,Max Planck Institute for Chemical Physics of Solids | Kreiner G.,Max Planck Institute for Chemical Physics of Solids | And 5 more authors.
Metals | Year: 2015

We report on the effects of annealing on the martensitic phase transformation in the Ni-based Heusler system: Mn50Ni40Sn10 and Mn50Ni41Sn9 powder and Co50Ni21Ga32 nanoparticles. For the powdered Mn50Ni40Sn10 and Mn50Ni41Sn9 alloys, structural and magnetic measurements reveal that post-annealing decreases the martensitic transformation temperatures and increases the transition hysteresis. This might be associated with a release of stress in the Mn50Ni40Sn10 and Mn50Ni41Sn9 alloys during the annealing process. However, in the case of Co50Ni21Ga32 nanoparticles, a reverse phenomenon is observed. X-ray diffraction analysis results reveal that the as-prepared Co50Ni21Ga32 nanoparticles do not show a martensitic phase at room temperature. Post-annealing followed by ice quenching, however, is found to trigger the formation of the martensitic phase. The presence of the martensitic transition is attributed to annealing-induced particle growth and the stress introduced during quenching. © 2015 by the authors; licensee MDPI, Basel, Switzerland. Source

Fabbrici S.,Mist Technologies | Fabbrici S.,Science 37 | Porcari G.,Science 37 | Porcari G.,University of Parma | And 6 more authors.
Entropy | Year: 2014

In Ni-Mn-Ga ferromagnetic shape memory alloys, Co-doping plays a major role in determining a peculiar phase diagram where, besides a change in the critical temperatures, a change of number, order and nature of phase transitions (e.g., from ferromagnetic to paramagnetic or from paramagnetic to ferromagnetic, on heating) can be obtained, together with a change in the giant magnetocaloric effect from direct to inverse.Here we present a thorough study of the intrinsic magnetic and structural properties, including their dependence on hydrostatic pressure, that are at the basis of the multifunctional behavior of Co and In-doped alloys. We study in depth their magnetocaloric properties, taking advantage of complementary calorimetric and magnetic techniques, and show that if a proper measurement protocol is adopted they all merge to the same values, even in case of first order transitions. A simplified model for the estimation of the adiabatic temperature change that relies only on indirect measurements is proposed, allowing for the quick and reliable evaluation of the magnetocaloric potentiality of new materials starting from readily available magnetic measurements. © 2014 by the authors. Source

Parini A.,Mist Technologies | Parini A.,University of Ferrara | Ramini L.,University of Ferrara | Lanzoni F.,University of Ferrara | And 2 more authors.
International Journal of Optics | Year: 2012

This work presents a bottom-up abstraction procedure based on the design-flow FDTD + SystemC suitable for the modelling of optical Networks-on-Chip. In this procedure, a complex network is decomposed into elementary switching elements whose input-output behavior is described by means of scattering parameters models. The parameters of each elementary block are then determined through 2D-FDTD simulation, and the resulting analytical models are exported within functional blocks in SystemC environment. The inherent modularity and scalability of the S-matrix formalism are preserved inside SystemC, thus allowing the incremental composition and successive characterization of complex topologies typically out of reach for full-vectorial electromagnetic simulators. The consistency of the outlined approach is verified, in the first instance, by performing a SystemC analysis of a four-input, four-output ports switch and making a comparison with the results of 2D-FDTD simulations of the same device. Finally, a further complex network encompassing 160 microrings is investigated, the losses over each routing path are calculated, and the minimum amount of power needed to guarantee an assigned BER is determined. This work is a basic step in the direction of an automatic technology-aware network-level simulation framework capable of assembling complex optical switching fabrics, while at the same time assessing the practical feasibility and effectiveness at the physical/technological level. © 2012 Alberto Parini et al. Source

Nipoti R.,CNR Institute for Microelectronics and Microsystems | Nath A.,George Mason University | Moscatelli F.,CNR Institute for Microelectronics and Microsystems | De Nicola P.,Mist Technologies | And 2 more authors.
Semiconductor Science and Technology | Year: 2012

The fabrication of a fully ion-implanted vertical p-i-n diode using high-purity semi-insulating 4H-SiC substrate has been demonstrated for the first time. The intrinsic region is the wafer itself with a thickness of 350 m. The anode and cathode are obtained by doping the front and back wafer surfaces with implanted Al +and P +ions, respectively, with concentrations of about 10 20cm 3. The electrical activation of the implanted dopants is obtained by microwave heating the samples up to 2100 °C for 30 s. At ±100 V the on and off state current ratio is in the order of 10 4. Forward saturation current is five orders larger than it would be if controlled by the series resistance of the thick HPSI 4HSiC intrinsic region. © 2012 IOP Publishing Ltd. Source

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