Search results for "A* algorithm"
showing 10 items of 2538 documents
An induction motor speed measurement method based on current harmonic analysis with the Chirp-Z Transform
2005
This paper presents a new method to measure motor speed by means of frequency estimation of rotor slot spectral components in the supply current of squirrel single-cage induction motors. The novelty of the method consists in the harmonic analysis of the supply current by means of the chirp-Z transform (CZT). The advantages are improved accuracy due to better spectral resolution and resolvability. Moreover, a shorter observation window is required, thus reducing errors related to nonstationary current signals. The experimental results are presented to validate the proposed method and to make a comparison with a similar method based on the fast Fourier transform (FFT).
An induction motor speed measurement based on current harmonic analysis with Chirp-Z Transform
2002
The paper presents a new method to measure motor speed by means of frequency estimation of rotor slot harmonics present in the supply current of squirrel single cage induction motors. The novelty of the method is the use of Chirp-Z Transform as supply current harmonic analysis. The advantages are an improved spectral resolution and accuracy. Moreover a shorter sampling time window is required reducing errors related to not stationary current signal. Experimental results are presented to validate the proposed method and to perform a comparison with FFT based one.
Variable Selection in Predictive MIDAS Models
2014
In short-term forecasting, it is essential to take into account all available information on the current state of the economic activity. Yet, the fact that various time series are sampled at different frequencies prevents an efficient use of available data. In this respect, the Mixed-Data Sampling (MIDAS) model has proved to outperform existing tools by combining data series of different frequencies. However, major issues remain regarding the choice of explanatory variables. The paper first addresses this point by developing MIDAS based dimension reduction techniques and by introducing two novel approaches based on either a method of penalized variable selection or Bayesian stochastic searc…
A distributed architecture for autonomous navigation of robots
2002
The paper shows a distributed architecture for autonomous robot navigation. The architecture is based on three modules that are implemented on separate and interacting agents: the target recognizer, the obsta90cle evaluator and the planner. An adaptive genetic algorithm has been studied to identify mechanisms for reaching the target and for manipulating the 2-directions of the robot; the distributed architecture has been embedded in the DAISY (Distributed Architecture for Intelligent System). Experiments have been carried out using a LEGO intelligent brick.
Overgrid: A Fully Distributed Demand Response Architecture Based on Overlay Networks
2017
In this paper, we present Overgrid, a fully distributed peer-to-peer (P2P) architecture designed to automatically control and implement distributed demand response (DR) schemes in a community of smart buildings with energy generation and storage capabilities. As overlay networks in communications establish logical links between peers regardless of the physical topology of the network, the Overgrid is able to apply some power balance criteria to its system of buildings, as they belong to a virtual microgrid, regardless of their physical location. We exploit an innovative distributed algorithm, called flow updating, for monitoring the power consumption of the buildings and the number of nodes…
Task scheduling control of BGA solder joint process in flexible manufacturing system
2006
This paper describes an open loop control method of the solder joint process in a rework station for faulty printed circuit board (PCBs) containing electronic components in packages ball grid arrays (BGAs). In particular, a mathematical model describing the solder joint process is, first of all, obtained. Then, the desired thermal profile of the junctions BGA-PCB is determined according to the physical constraints of the rework station framework. The control parameters corresponding to the above desired thermal profile are identified using the above mathematical model. Finally, the open loop control algorithm is implemented on the supervisor interface of the rework station in order to carri…
Multi-step ahead wind speed forecasting using an improved wavelet neural network combining variational mode decomposition and phase space reconstruct…
2017
Abstract Accurate wind speed forecasting is crucial to reliable and secure power generation system. However, the intermittent and unstable nature of wind speed makes it very difficult to be predicted accurately. This paper proposes a novel hybrid model based on variational mode decomposition (VMD), phase space reconstruction (PSR) and wavelet neural network optimized by genetic algorithm (GAWNN) for multi-step ahead wind speed forecasting. In the proposed model, VMD is firstly applied to disassemble the original wind speed series into a number of components in order to improve the overall prediction accuracy. Then, the multi-step ahead forecasting for each component is conducted using GAWNN…
Optimum Performance of Permanent Magnet Synchronous Generators Coupled to Wind Turbines
2007
In this paper a control algorithm for the efficiency improvement of permanent magnet synchronous generators (PMSG) is presented. The proposed algorithm reduces the losses of the generator without affecting its performances. In details, after a description of a dynamic model of the PMSG, which has been purposely modified in order to take into account the iron losses, the basic equations and the constraints to obtain the loss minimization are presented and discussed. Some simulations of a specific PMSG employing the proposed algorithm are performed. The results of these simulations show that enhancement of the efficiency up to 3% can be reached in comparison to a PMSG using a traditional cont…
Consensus-based Distributed Intrusion Detection for Multi-Robot Systems
2008
This paper addresses a security problem in robotic multi-agent systems, where agents are supposed to cooperate according to a shared protocol. A distributed Intrusion Detection System (IDS) is proposed here, that detects possible non-cooperative agents. Previous work by the authors showed how single monitors embedded on-board the agents can detect non- cooperative behavior, using only locally available information. In this paper, we allow such monitors to share the collected information in order to overcome their sensing limitation. In this perspective, we show how an agreement on the type of behavior of a target-robot may be reached by the monitors, through execution of a suitable consensu…
Fiber laser mode locked through an evolutionary algorithm
2015
Mode locking of fiber lasers generally involves adjusting several control parameters, in connection with a wide range of accessible short-pulse dynamics. In this Letter, we experimentally demonstrate the ability of an evolutionary algorithm to prescribe a set of cavity parameters entailing specific self-starting mode locking. The prescribed parameters are applied to electrically driven polarization controllers, thus shaping the effective nonlinear transfer function at play within the fiber cavity. According to the specifications of the objective function used for the optimization procedure, various short-pulse regimes are obtained. Our versatile method represents an effective novel avenue f…