Search results for "circuit"

High accuracy Raman measurements using the Stokes and anti-Stokes lines

1997

We show that by measuring the separation between the Stokes and anti-Stokes peaks excited by two different laser lines we obtain a very precise determination of absolute phonon energies. The method is useful for measuring small changes of these energies with strain, temperature, laser power, etc. It doubles the changes and avoids the necessity of using the reference lines in the Raman spectra. The method can be applied for the determination of phonon deformation potentials, for the characterization of strained heteroepitaxial layers, and for micro-Raman analysis of strain in silicon integrated circuits. We give examples of phonon shifts in Si, Ge, GaAs, InAs, and GaP as a function of applie…

A PV plant simulator for testing MPPT techniques

2013

This paper introduces a versatile and reliable photovoltaic systems simulator. It includes the main components of a photovoltaic plant: a PV string and a PWM controlled boost chooper. The key feature of this simulator is the ability to consider different and non-uniform irradiation and temperature conditions (partial shading and partial heating of the strings). All the different I-V and P-V or P-I characteristics can then be determined in such non-uniform irradiation and temperature conditions, with the aim to try different MPPT algorithms. The simulator also allows to verify an enhanced version of the Incremental Conductance algorithm (IncCond) where, in order to reach the real absolute ma…

An interface protection system based on an embedded metrology system platform

2021

Abstract The aim of this work is to present an interface protection system (IPS) for Distributed Generators (DG) and Energy Storage Systems (ESS). The new prototype of IPS guarantees standard protection requirements, in terms of both voltage and frequency measurement accuracies and trip times. Moreover, it has the additional functionalities of implementing a communication link between the Distribution System Operator (DSO) and the DG and ESS Inverter. The new IPS is based on a smart meter platform with an integrated power line communication modem. Moreover, it has also an integrated metrology section. Experimental tests will show how this last feature allows a significant reduction of the m…

Impact of centrality on cooperative processes

2016

The solution of today's complex problems requires the grouping of task forces whose members are usually connected remotely over long physical distances and different time zones. Hence, understanding the effects of imposed communication patterns (i.e., who can communicate with whom) on group performance is important. Here, we use an agent-based model to explore the influence of the betweenness centrality of the nodes on the time the group requires to find the global maxima of NK-fitness landscapes. The agents cooperate by broadcasting messages, informing on their fitness to their neighbors, and use this information to copy the more successful agents in their neighborhood. We find that for ea…

Acid versus base peptization of mesoporous nanocrystalline TiO2 films: functional studies in dye sensitized solar cells

2005

We report an analysis of the influence of acid/base conditions employed in the synthesis of TiO2 nanoparticles upon the performance of dye sensitised photoelectrochemical solar cells fabricated from these particles. The functional properties of the TiO2 nanoparticles in these devices are investigated by potential step chronoamperometry, transient laser spectroscopy, and photovoltaic device characterisation. We find that base peptization conditions employed in the sol–gel fabrication of the TiO2 nanoparticles result in a reduction in film electron density under negative applied bias, correlated with slower interfacial recombination losses and a higher device open circuit voltage.

Topology of correlation-based minimal spanning trees in real and model markets

2003

We present here a topological characterization of the minimal spanning tree that can be obtained by considering the price return correlations of stocks traded in a financial market. We compare the minimal spanning tree obtained from a large group of stocks traded at the New York Stock Exchange during a 12-year trading period with the one obtained from surrogated data simulated by using simple market models. We find that the empirical tree has features of a complex network that cannot be reproduced, even as a first approximation, by a random market model and by the one-factor model.

Sistema di misura per l’analisi spettrale di segnali non stazionari: implementazione in VHDL per lo sviluppo di un prototipo su FPGA

2010

Measurement technique for real-time and low-cost biosensing using photonic bandgap structures

2011

We present a sensing technique based on using photonic bandgap structures where only the output power is monitored, without the need of tunable sources or spectrum analyzers, thus providing a real-time and low-cost system.

Optimization of Reactive Force Field Simulation: Refactor, Parallelization, and Vectorization for Interactions

2022

Molecular dynamics (MD) simulations are playing an increasingly important role in many areas ranging from chemical materials to biological molecules. With the continuing development of MD models, the potentials are getting larger and more complex. In this article, we focus on the reactive force field (ReaxFF) potential from LAMMPS to optimize the computation of interactions. We present our efforts on refactoring for neighbor list building, bond order computation, as well as valence angles and torsion angles computation. After redesigning these kernels, we develop a vectorized implementation for non-bonded interactions, which is nearly $100 \times$ 100 × faster than the management processing…

Circuits and excitations to enable Brownian token-based computing with skyrmions

2021

Brownian computing exploits thermal motion of discrete signal carriers (tokens) for computations. In this paper we address two major challenges that hinder competitive realizations of circuits and application of Brownian token-based computing in actual devices for instance based on magnetic skyrmions. To overcome the problem that crossings generate for the fabrication of circuits, we design a crossing-free layout for a composite half-adder module. This layout greatly simplifies experimental implementations as wire crossings are effectively avoided. Additionally, our design is shorter to speed up computations compared to conventional designs. To address the key issue of slow computation base…