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Human Exposure Assessment in Dynamic Inductive Power Transfer for Automotive Applications
No full textThis paper proposes a methodology for the assessment of the human exposure to magnetic fields generated by dynamic inductive power transfer systems for automotive applications. Since the magnetic field is pulsed, current safety standards and guidelines require the use of time-domain approaches to evaluate the peak exposure, which has to be limited under the prescribed limits. This paper shows that, for these kind of systems, the peak exposure can be efficiently evaluated by means of a time-harmonic formulation. Furthermore, a methodology to identify the worst case scenario is proposed and applied to a real case
Uncertainty quantification in Discrete Fracture Network models: stochastic geometry
No full textWe consider the problem of uncertainty quantification analysis of the output of underground flow simulations. We consider in particular fractured media described via the discrete fracture network model; within this framework, we address the relevant case of networks in which the geometry of the fractures is described by stochastic parameters. In this context, due to a possible lack of smoothness in the quantity of interest with respect to the stochastic parameters, well assessed techniques such as stochastic collocation may fail in providing reliable estimates of first order moments of the quantity of interest. In this paper we overcome this issue by applying the Multilevel Monte Carlo method, using as underlying solver an extremely robust method
Feature issue introduction: Multimaterial and Multifunctional Optical Fibers
No full textThe development of multimaterial and multifunctional optical fibers is opening exciting opportunities in photonic and optoelectronic devices, optical probes, diagnosis and surgical tools, as well as advanced fibers and textiles. It also constitutes a rich platform for the fundamental study of novel materials science and processing concepts, as well as in optics and photonics. This Feature Issue is a collection of thirteen peer-reviewed articles that present original work in areas at the frontier of this emerging scientific and technological field. These contributions highlight the maturity of the techniques employed to date, their potential tofurther develop and the prospects for a new generation of optical fiber based devices
G.POT: a method for the assessment and mapping of the near-surface geothermal potential
No full textShallow geothermal systems are widely recognised as a valuable technology for the heating and cooling of buildings. The most adopted technology is the Borehole Heat Exchanger (BHE), since it can be installed almost everywhere. However, the economic viability of BHEs depends on the thermal load that can be efficiently exchanged with the ground, i.e. the near-surface geothermal potential. We present the G.POT (Geothermal POTential) method for the assessment of near-surface geothermal potential as a function of the thermal conductivity and capacity of the ground, of its initial temperature, of the thermal resistance of the BHE and of the duration of the sinusoidal thermal load cycle, which reproduces the typical pattern of a thermal load during a heating or a cooling season. The function was calibrated from the results of numerical heat transfer simulations, performed varying the values of the aforementioned parameters over broad ranges. G.POT is a simple mathematical tool which can be easily implemented for the large-scale assessment and mapping of the near-surface geothermal potential for heating or cooling purpose. An example of its application is also shown, and advice is provided on the processing of input parameters
A novel image processing technique for three-dimensional volumetric analysis of severely resorbed alveolar sockets with cone beam computed tomography
No full textThe aim of this study was to present and validate a novel procedure for the quantitative volumetric assessment of extraction sockets that combines Cone-Beam Computed Tomography (CBCT) and image processing techniques
Itinerario nell'arte (Quarta Edizione) Dal Gotico Internazionale all'età barocca (Versione Verde)
No full textManuale di Storia dell'arte a uso della scuola secondaria superior
Advances in quantum tunneling models for semiconductor optoelectronic device simulation
No full textThe undiscussed role of solid-state optoelectronics covers nowadays a wide range of applications. Within this scenario, infrared (IR) detection is becoming crucial by the technological point of view, as well as for scientific purposes, from biology to aerospace. Its commercial and strategic role, however, is confirmed by its spreading use for surveillance, clinical diagnostics, environmental analysis, national/private security, military purposes or quality control as in food industry. At the same time solid-state lighting is emerging among the most efficient electronic applications of the modern era, with a billion-dollar business which is just destined to increase in the next decades. The ongoing development of such technologies must be accompanied by a sufficiently fast scientific progress, which is able to meet the growing demand of high-quality production standards and, as immediate but not obvious consequence, the need of performances which would be the highest possible. One issue affecting both kinds of applications we mentioned is the quantum efficiency, no matter the signal they produce is coming from absorbed or emitted photons. At any rate, the balance between the stimulus coming from the surrounding environment is and the generated electrical current is absolutely crucial in each modern optoelectronic device. More in depth, since IR detectors are asked to convert photons into electrons, device designers must ensure that mechanisms concurring to this conversion should be dominant with respect to any opponent phenomenon. Symmetrically, light-emitting diodes should realize the inverse process, where electrons are converted into photons. In real life this mechanism never take place in a one-to-one electron-photon correspondence. Indeed tunneling, a quantum effect related to the probabilistic nature of particles and, thus, also of charges, contributes to unbalance this correspondence by degrading the signal produced within the device active region. In IR photodetectors this translates into of a current even in absence of light (and, by virtue of this fact, this current is known as "dark current") while in light-emitters tunneling is responsible for leakages that may undermine the quantum efficiency and the power consumption also below the optical turn-on. The present dissertation is part of such framework being the result of studying and modeling different tunneling mechanisms occurring in narrow-gap infrared photodetectors (IRPDs) for mid-wavelength IR (MWIR) applications (3 to 5 um) and in wide-gap blue LEDs (around 450 nm) based on nitride material system. This study has been possible thanks to the collaboration with several academic institutions (Boston University, Padua and Modena e Reggio Emilia Universities) and two important German industries, AIM Infrarot Module and OSRAM Opto Semiconductors, which provided the case-study devices here analyzed. After reviewing basic concepts of solid-state physics, the first part of this work deals with the description of the above cited optoelectronic devices, along with their constituent materials: the HgCdTe alloy, in the case of photodetectors, and GaN and its ternary alloys with In and Al, for what concerns blue LEDs. Since the literature focusing on this research area is still not mature enough, in the second part different tunneling mechanisms and models are proposed, described in detail and then tested for the first time, as in the case of a novel formulation intended for direct tunneling in IRPDs or the description of defect-assisted tunneling in LEDs which also includes elements coming from the microscopic theory of multiphonon emission (MPE) in solids. Simulations are carried out by means of several numerical simulation approaches, using either commercial TCAD (Technology Computer Aided Design) tools and codes developed ad hoc for this purpose. The encouraging and fully satisfying results of numerical modeling here proposed confirm, on the one hand, the widely accepted relevance of tunneling in modern electronics and, on the other hand, also propose a new perspective about possible tunneling mechanism in optoelectronic devices and their appropriate physical, mathematical and numerical investigation tools. Furthermore, the role of device modeling does not end here because many physical details and technological information can be inferred from simulations, with enormous beneficial effects for the electronic industry and the quality improvement of its fabrication processes such those invoked above