Search results for "Width"
showing 10 items of 690 documents
Optimal band selection for future satellite sensor dedicated to soil science
2009
Hyperspectral imaging systems could be used for identifying the different soil types from the satellites. However, detecting the reflectance of the soils in all the wavelengths involves the use of a large number of sensors with high accuracy and also creates a problem in transmitting the data to earth stations for processing. The current sensors can reach a bandwidth of 20 nm and hence, the reflectance obtained using the sensors are the integration of reflectance obtained in each of the wavelength present in the spectral band. Moreover, not all spectral bands contribute equally to classification and hence, identifying the bands necessary to have a good classification is necessary to reduce …
Forward likelihood-based predictive approach for space-time point processes
2011
Dealing with data from a space–time point process, the estimation of the conditional intensity function is a crucial issue even if a complete definition of a parametric model is not available. In particular, in case of exploratory contexts or if we want to assess the adequacy of a specific parametric model, some kind of nonparametric estimation procedure could be useful. Often, for these purposes kernel estimators are used and the estimation of the intensity function depends on the estimation of bandwidth parameters. In some fields, like for instance the seismological one, predictive properties of the estimated intensity function are pursued. Since a direct ML approach cannot be used, we pr…
A novel digital control for DC/DC converters to improve steady-state performances
2006
This paper describes an innovative digital PWM control implementation for low voltage, high current DC-DC converters. The proposed technique, based on the use of a low resolution DAC, improves steady-state performances, minimizing limit cycle effects. The novel technique is tested on a FPGA-based single phase buck converter operating at 250 kHz. A detailed description of the proposed architecture is given and test results, simulation and experimental ones, are shown
Hybrid Modelling and Control of a Class of Power Converters With Triangular-Carrier PWM Inputs
2021
In this paper, a new control design procedure for a class of power converters based on hybrid dynamical systems theory is presented. The continuous-time dynamics, as voltage and current signals, and discretetime dynamics, as the on-off state of the switches, are captured with a hybrid model. This model avoids the use of averaged and approximated models and includes the PWM as well as the sample-and-hold mechanism, commonly used in the industry. Then, another simplified hybrid system, whose trajectories match with the original one, is selected to design the controller and to analyse stability properties. Finally, an estimation of the chattering in steady state of the voltage and current sign…
Bimodal Approach for Noise Figures of Merit Evaluation in Quantum-Limited Josephson Traveling Wave Parametric Amplifiers
2022
The advent of ultra-low noise microwave amplifiers revolutionized several research fields demanding quantum-limited technologies. Exploiting a theoretical bimodal description of a linear phase-preserving amplifier, in this contribution we analyze some of the intrinsic properties of a model architecture (i.e., an rf-SQUID based Josephson Traveling Wave Parametric Amplifier) in terms of amplification and noise generation for key case study input states (Fock and coherents). Furthermore, we present an analysis of the output signals generated by the parametric amplification mechanism when thermal noise fluctuations feed the device.
Landau damping in high-temperature superconductors
1995
We investigate the decay of a phonon into single-electron excitations in the cuprate superconductors. In a clean crystal the screening of the longitudinal phonon field cancels singularity of the Landau damping threshold and makes it experimentally unobservable. In a dirty metal the phase volume of the electrons involved in damping is small, which reduces the probability of the phonon decay. However, in this case the observation of dependence between the phonon linewidth and light penetration depth is more favorable than in the clean metal because the damping has no threshold.
Spectrum Hole Detection for Cognitive Radio through Energy Detection using Random Forest
2020
The growth of wireless data is the major driving force for an exponential increase in wireless communication. Cognitive Radio is one of the emerging wireless technologies that can be used for smart utility networks. Optimum utilization of the wireless spectrum is the objective of Cognitive Radio. Finding a spectrum hole through intelligent means is essential for the success of Cognitive Radio. Dynamic spectrum allocation is also an efficient technique for spectrum allocation. It will lead to a better spectrum utilization. In this paper, some of the machine learning techniques are used to find a frequency range for dynamic spectrum allocation. Different machine learning techniques such as Lo…
A reexamination of voltage distortion for classical carrier-based vs B-Spline modulation of three-phase Voltage Sources Inverters
2015
Voltage waveform improvement has been the object of several investigations for many years and a manifold of different solutions have been proposed to reduce the harmonic content in Voltage Source Inverters (VSI) power application. In many cases this improvements have been obtained by modifying the reference voltage modulating signal. The recent introduction of cardinal B-spline functions, used as carrier signals, has given rise to a new modulation technique whose main characteristic is a lower value of the Total Harmonic Distortion (THD). After the discussion on the B-Spline modulation principle and on its computational effort, a performance comparisons is carried out by means of Total Harm…
Remote Patient Monitoring Within a Future 5G Infrastructure
2010
Published version of an article from the journal: Wireless Personal Communications. The original publication is available at Spingerlink. http://dx.doi.org/10.1007/s11277-010-0078-5 Systems of wearable or implantable medical devices (IMD), sensor systems for monitoring and transmitting physiological recorded signals, will in future health care services be used for purposes of remote monitoring. Today, there exist several constraints, probably preventing the adoption of such services in clinical routine work. Within a future 5G infrastructure, new possibilities will be available due to improved addressing solutions and extended security services in addition to higher bandwidth in the wireles…
Comprehensive Modeling and Experimental Testing of Fault Detection and Management of a Nonredundant Fault-Tolerant VSI
2015
This paper presents an investigation and a comprehensive analysis on fault operations in a conventional three-phase voltage source inverter. After an introductory section dealing with power converter reliability and fault analysis issues in power electronics, a generalized switching function accounting for both healthy and faulty conditions and an easy and feasible method to embed fault diagnosis and reconfiguration within the control algorithm are introduced. The proposed system has simple and compact implementation. Experimental results operating both at open- and closed-loop current control, obtained using a test bench realized using a dSPACE system and the fault-tolerant inverter protot…