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Search Results: 1 - 10 of 6057 matches for " Stefano Perticaroli "
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Floquet Eigenvectors Theory of Pulsed Bias Phase and Quadrature Harmonic Oscillators  [PDF]
Fabrizio Palma, Stefano Perticaroli
Circuits and Systems (CS) , 2012, DOI: 10.4236/cs.2012.31010
Abstract: The paper presents an analytical derivation of Floquet eigenvalues and eigenvectors for a class of harmonic phase and quadrature oscillators. The derivation refers in particular to systems modeled by two parallel RLC resonators with pulsed energy restoring. Pulsed energy restoring is obtained through parallel current generators with an impulsive characteristic triggered by the resonators voltages. In performing calculation the initial hypothesis of the existence of stable oscillation is only made, then it is verified when both oscillation amplitude and eigenvalues/eigenvectors are deduced from symmetry conditions on oscillator space state. A detailed determination of the first eigenvector is obtained. Remaining eigenvectors are hence calculated with realistic approximations. Since Floquet eigenvectors are acknowledged to give the correct decomposition of noise perturbations superimposed to the oscillator space state along its limit cycle, an analytical and compact model of their behavior highlights the unique phase noise properties of this class of oscillators.
Phase and Quadrature Pulsed Bias LC-CMOS VCO  [PDF]
Stefano Perticaroli, Fabrizio Palma, Adriano Carbone
Circuits and Systems (CS) , 2011, DOI: 10.4236/cs.2011.21004
Abstract: Pulsed bias is an attempt to improve the performance of oscillators in integrated circuits as a result of architectural innovation. Given the relatively low value of resonator quality factor achievable on-chip, for a specified bias voltage level, pulsed bias may result in a lower power consumption and in an improvement of the spectral purity of the oscillation. The main drawback of this approach is the need to introduce a certain time delay in order to properly position pulses with respect to oscillation waveform. Delay accumulation requires further energy dissipation and introduce additional jitter. In this paper we present a new architecture capable to avoid unnecessary delay, based on the idea to apply the pulsed bias approach to a quadrature oscillator. A ?rst circuit-level implementation of this concept is presented with simulation results.
Derivation of Floquet Eigenvectors Displacement for Optimal Design of LC Tank Pulsed Bias Oscillators  [PDF]
Stefano Perticaroli, Nikend Luli, Fabrizio Palma
Circuits and Systems (CS) , 2011, DOI: 10.4236/cs.2011.24043
Abstract: The paper presents an approximated and compact derivation of the mutual displacement of Floquet eigenvectors in a class of LC tank oscillators with time varying bias. In particular it refers to parallel tank oscillators of which the energy restoring can be modeled through a train of current pulses. Since Floquet eigenvectors are acknowledged to give a correct decomposition of noise perturbations along the stable orbit in oscillator's space state, an analytical and compact model of their displacement can provide useful criteria for designers. The goal is to show, in a simplified case, the achievement of oscillators design oriented by eigenvectors. To this aim, minimization conditions of the effect of stationary and time varying noise as well as the contribution of jitter noise introduced by driving electronics are deduced from analytical expression of eigenvectors displacement.
CMOS Phase and Quadrature Pulsed Differential Oscillators Coupled through Microstrip Delay-Lines  [PDF]
Francesco Stilgenbauer, Stefano Perticaroli, Fabrizio Palma
Circuits and Systems (CS) , 2014, DOI: 10.4236/cs.2014.58020
Abstract:

An innovative solution to design phase and quadrature pulsed coupled oscillators systems through electromagnetic waveguides is described in this paper. Each oscillator is constituted by an LC differential resonator refilled through a couple of current pulse generator circuits. The phase and quadrature coupling between the two differential oscillators is achieved using delayed replicas of generated fundamentals from a resonator as driving signal of pulse generator injecting in the other resonator. The delayed replicas are obtained by microstrip-based delay-lines. A 2.4 - 2.5 GHz VCO has been implemented in a 150 nm RF CMOS process. Simulations showed at 1 MHz offset a phase noise of -139.9 dBc/Hz and a FOM of -189.1 dB.

Feasibility Evaluation of Integrating UsabilityEngineering Issues in a Design for Multi-XCollaborative Framework  [PDF]
Stefano Filippi
Intelligent Information Management (IIM) , 2011, DOI: 10.4236/iim.2011.31004
Abstract: Design for manufacturing, design for assembly, and, in general, design for X, are methods helping an effective generation of industrial products. In parallel with the development of these methods, the research about usability engineering has generated many important results, both from the design, and the evaluation and testing points of view. The research described in this paper aims at evaluating the feasibility of the integration of two new usability methods, the design for innovative usability - DFIU -, and the integrated method for usability evaluation and testing - IMUET -, in an existing design for X named design guidelines collaborative framework - DGLs-CF -. Indeed, the DGLs-CF is a design for multi-X method, given that it covers both the manufacturing and the verification phases of the industrial product lifecycle. All these methods are currently under development by the author’s research group. To evaluate this feasibility, the first task of the research aims at describing and classifying the components of the three methods. Next, these components are semantically related to each other. Finally, the last activity verifies the compatibility between the components of the two usability methods and the data structures of the DGLs-CF to check the feasibility from the implementation point of view. The result of this research will consist of precise indications both for the development of a design for multi-X collaborative framework covering homogeneously the design, manufacturing, verification, and use phases of the industrial product lifecycle, and to be used as a reference for researchers interested in considering the integration of usability issues in their design tools, methods, and processes.
A General Purpose Analysis Package  [PDF]
Stefano Federico
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.22022
Abstract: This paper presents a general-purpose analysis package able to solve two- and three- dimensional analysis problems. The system can use the following methods of solution: Successive Approximation (SA), Optimal Interpolation (OI), and 3D-Var. Analyses are given for the following parameters: zonal and meridional wind components, temperature, relative humidity, and geopotential height. The analysis package was applied to produce analyses at 6 h time interval for the period 1-11 August 2008. The period was selected for data availability and forty-one analyses were collected. The results show the validity of the different solutions, which can be chosen depending on the physical problem to solve and on the computational resources available. In particular, assuming the observations as the reference, all solutions show a decrease of the RMSE compared to the background. The decrease is consistent with the particular setting of the analysis system used in this paper. The comparison between different solutions shows that the SA converges to OI in few iterations, and that the SA solution with ten iteration is, in practice, equal to OI. Moreover, the 3D-Var method shows its potential to improve the analysis, once the horizontal and vertical length-scales and the background and observational errors are set optimally, because its solution may be sizeably different from two-dimensional methods.
Preliminary Results of a Data Assimilation System  [PDF]
Stefano Federico
Atmospheric and Climate Sciences (ACS) , 2013, DOI: 10.4236/acs.2013.31009
Abstract:

A data assimilation system combines all available information on the atmospheric state in a given time-window to produce an estimate of atmospheric conditions valid at a prescribed analysis time. Nowadays, increased computing power coupled with greater access to real-time asynoptic data is paving the way toward a new generation of high-resolution (i.e. on the order of 10 km) operational mesoscale analyses and forecasting systems. Moreover, better initial conditions are increasingly considered of the utmost importance for Numerical Weather Prediction (NWP) at the short range (0 - 12 h). This paper presents a general-purpose data assimilation system, which is coupled with the Regional Atmospheric Modelling System (RAMS) to give the analyses for: zonal and meridional wind components, temperature, relative humidity, and geopotential height. In order to show its potential, the data assimilation systems applied to produce analyses over Central Europe. For this application the background field is given by a short-range forecast (12 h) of the RAMS and analyses are produced by 2D-Var with 0.25? horizontal resolution. Results show the validity of the analyses because they are closer to the observations, consistently with the settings of the data assimilation system. To quantify the impact of improved initial conditions on the forecast, the analyses are then used as initial conditions of a short-range (6 h) forecast of the RAMS model. The results show that the RMSE is effectively reduced for the one- and two hours forecast, with some improvement for the three-hours forecast.

Continued Fractions and Dynamics  [PDF]
Stefano Isola
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.57101
Abstract:

Several links between continued fractions and classical and less classical constructions in dynamical systems theory are presented and discussed.


Revealed Cores: Characterizations and Structure  [PDF]
Stefano Vannucci
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.614200
Abstract: Characterizations of the classes of all choice functions that select the cores or the externally stable cores induced by an underlying revealed dominance digraph are provided. Relying on such characterizations, the basic order-theoretic structure of the corresponding sets of revealed cores is also analyzed. In particular, it is shown that the poset of all revealed cores ordered by set inclusion is a median meet semilattice: therefore, any profile of revealed cores may be aggregated by means of the simple majority rule.
Italian Banks’ Paths through the Crisis  [PDF]
Stefano Zedda
Modern Economy (ME) , 2016, DOI: 10.4236/me.2016.73026
Abstract: Over the past seven years, the financial system has undergone an unprecedented crisis, which has caused important changes in the structure and business models of banks. This paper explores the main changes in the structure of Italian banks’ assets in 2007-2013, by size and category, as a result of the financial crisis and of regulatory and business models changes. The analysis shows that the effects of the crisis were very different on different categories, and that business models have changed, pushing the different banking categories to business models and balances increasingly similar.
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