270 research outputs found
Architectural Improvements Towards an Efficient 16-18 Bit 100-200 MSPS ADC
As Data conversion systems continue to improve in speed and resolution, increasing demands are placed on the performance of high-speed Analog to Digital Conversion systems. This work makes a survey about all these and proposes a suitable architecture in order to achieve the desired specifications of 100-200MS/s with 16-18 bit of resolution. The main architecture is based on paralleled structures in order to achieve high sampling rate and at the same time high resolution. In order to solve problems related to Time-interleaved architectures, an advanced randomization method was introduced. It combines randomization and spectral shaping of mismatches. With a simple low-pass filter the method can, compared to conventional randomization algorithms, improve the SFDR as well as the SINAD. The main advantage of this technique over previous ones is that, because the algorithm
only need that ADCs are ordered basing on their time mismatches, the absolute accuracy of the mismatch identification method does not matter and, therefore, the
requirements on the timing mismatch identification are very low. In addition to that, this correction system uses very simple algorithms able to correct not only for
time but also for gain and offset mismatches
Effects of Tourism on Venice: Commercial Changes over 30 Years
Tourism is becoming one of the most important economic drivers in the urban context. With this in mind, several cities have tried to adapt their economies to satisfy the demands of the influx of tourism. The main consequences of this trend are the re-shaping of urban areas, with particular regard to art cities. This phenomenon is particularly evident in Venice’s historical city centre. In order to better comprehend the changes that have taken place, we have put together a research based analysis of the commercial structure of the city. Particular attention has been given to comparing and contrasting the retail business over the last thirty years.commercial structure, historical city centre, retail, Venice
Estimating Koopman operators for nonlinear dynamical systems: a nonparametric approach
The Koopman operator is a mathematical tool that allows for a linear
description of non-linear systems, but working in infinite dimensional spaces.
Dynamic Mode Decomposition and Extended Dynamic Mode Decomposition are amongst
the most popular finite dimensional approximation. In this paper we capture
their core essence as a dual version of the same framework, incorporating them
into the Kernel framework. To do so, we leverage the RKHS as a suitable space
for learning the Koopman dynamics, thanks to its intrinsic finite-dimensional
nature, shaped by data. We finally establish a strong link between kernel
methods and Koopman operators, leading to the estimation of the latter through
Kernel functions. We provide also simulations for comparison with standard
procedures.Comment: Pre-print submitted for 19th IFAC Symposium, System Identification:
learning models for decision and contro
Perception of interactive vibrotactile cues on the acoustic grand and upright piano
An experiment has been conducted, measuring pianists’ sensitivity to piano key vibrations at the fingers while playing an upright or a grand Yamaha Disklavier piano. At each trial, which consisted in playing loud and long A notes across the whole keyboard, vibrations were either present or absent through setting the Disklavier pianos to normal or quiet mode. Sound feedback was always provided by a MIDI controlled piano synthesizer via isolating ear/headphones, which masked the acoustic sound in normal mode. In partial disagreement with the existing literature, our results suggest that significant vibrotactile cues
are produced in the lower range of the piano keyboard, with perceptual cut-off around the middle octave. Possible psychophysical mechanisms supporting the existence of such cues are additionally discussed
A Reinforcement Learning Approach to Sensing Design in Resource-Constrained Wireless Networked Control Systems
In this paper, we consider a wireless network of smart sensors (agents) that
monitor a dynamical process and send measurements to a base station that
performs global monitoring and decision-making. Smart sensors are equipped with
both sensing and computation, and can either send raw measurements or process
them prior to transmission. Constrained agent resources raise a fundamental
latency-accuracy trade-off. On the one hand, raw measurements are inaccurate
but fast to produce. On the other hand, data processing on resource-constrained
platforms generates accurate measurements at the cost of non-negligible
computation latency. Further, if processed data are also compressed, latency
caused by wireless communication might be higher for raw measurements. Hence,
it is challenging to decide when and where sensors in the network should
transmit raw measurements or leverage time-consuming local processing. To
tackle this design problem, we propose a Reinforcement Learning approach to
learn an efficient policy that dynamically decides when measurements are to be
processed at each sensor. Effectiveness of our proposed approach is validated
through a numerical simulation with case study on smart sensing motivated by
the Internet of Drones.Comment: 8 pages, 4 figures, submitted to CDC 2022; fixed author name
Methodology for Minimizing Mismatches in Time-Interleaved ADCs
This presentation describes a technique mitigating the impact of timing mismatches in timeinterleaved
analog-to-digital converters (ADCs). The systems signal-to-noise and distortion ratio (SINAD) and spurious-free dynamic range (SFDR) are increased by controlling the selection order of the channels ADCs in combination with oversampling and consecutive filtering. The proposed method
requires only knowledge of the relative level of timing mismatch between the channel ADCs though not the precise magnitude of the mismatch. The impact of timing mismatch on the SINAD and advanced selection ordering schemes are discussed. Moreover, simulation results are presented
comparing the figures of merit of existing techniques
Design of Thermal Management Control Policies for Multiprocessors Systems on Chip
The contribution of this thesis is a thorough study of thermal aware policy design for MPSoCs. The study includes the modelling of their thermal behavior as well as the improvement and the definition of new thermal management and balancing policies. The work is structured on three main specific disciplines. The areas of contributions are: modeling, algorithms and system design. This thesis extends the field of modeling by proposing new techniques to represent the thermal behavior of MPSoCs using a mathematical formalization. Heat transfer and modelling of physical properties of MPSoCs have been extensively studied. Special emphasis is given to the way the system cools down (i.e. micro-cooling, natural heat dissipation etc.) and the heat propagates inside the MPSoC. The second contribution of this work is related to policies, which manage MPSoC working frequencies and micro-cooling pumps to satisfy user requirements in the most effective possible way, while consuming the lowest possible amount of resources. Several families of thermal policies algorithms have been studied and analyzed in this work for both 2D and 3D MPSoCs including liquid cooling technologies. The discipline of system design has also been extended during the development of this thesis. Thermal management policies have been implemented in real emulation platforms and contributions in this area are related to the design and implementation of proposed innovations in real MPSoC platforms
To Compute or not to Compute? Adaptive Smart Sensing in Resource-Constrained Edge Computing
We consider a network of smart sensors for edge computing application that
sample a signal of interest and send updates to a base station for remote
global monitoring. Sensors are equipped with sensing and compute, and can
either send raw data or process them on-board before transmission. Limited
hardware resources at the edge generate a fundamental latency-accuracy
trade-off: raw measurements are inaccurate but timely, whereas accurate
processed updates are available after computational delay. Also, if sensor
on-board processing entails data compression, latency caused by wireless
communication might be higher for raw measurements. Hence, one needs to decide
when sensors should transmit raw measurements or rely on local processing to
maximize overall network performance. To tackle this sensing design problem, we
model an estimation-theoretic optimization framework that embeds computation
and communication delays, and propose a Reinforcement Learning-based approach
to dynamically allocate computational resources at each sensor. Effectiveness
of our proposed approach is validated through numerical simulations with case
studies motivated by the Internet of Drones and self-driving vehicles.Comment: 14 pages, 14 figures; submitted to IEEE TNSM; revised versio
Diazo transfer for azido-functional surfaces
Preparation of azido-functionalized polymers is gaining increasing attention. We wish to report an innovative, novel strategy for azido functionalization of polymeric materials, coupling plasma technology and solution processed diazo transfer reactions. This novel approach allows the azido group to be introduced downstream of the material preparation, thus preserving its physicochemical and mechanical characteristics, which can be tailored a priori according to the desired application. The whole process involves the surface plasma functionalization of a material with primary amino groups, followed by a diazo transfer reaction, which converts the amino functionalities into azido groups that can be exploited for further chemoselective reactions. The diazo transfer reaction is performed in a heterogeneous phase, where the azido group donor is in solution. Chemical reactivity of the azido functionalities was verified by subsequent copper-catalyzed azide-alkyne cycloaddition
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