Search results for " Methods"
showing 10 items of 4102 documents
Bio-electromagnetic Numerical Modeling for Health Diagnostics
A Backward Method for Solving PV Nodes in Weakly Meshed Distribution Networks
2007
In this paper, a new iterative backward/forward methodology for the load flow solution of weakly meshed systems with fixed voltage nodes is presented. Such technique models the loads at each iteration by means of impedances, and the PV nodes by means of reactances. Each iteration is organised in two steps. In the first, the radial network attained from the meshed system through cuts and composed of shunt and series impedances is solved. In the second step, based on a reduced Thévenin impedance matrix, the compensation currents to be injected in the cut nodes are deduced. Modelling the PV nodes by means of reactances allows the attainment, for the reactive power of these nodes, of the same p…
An analytical model for PQ sources in backward/forward methods for distribution networks analysis
2004
In this paper a model of PQ sources useful for distribution systems analysis is developed. In the considered systems there are, in addition to HV/MV sources, other PQ buses, namely active and reactive power supply nodes (Vδ nodes). The general solution strategy is an iterative forward/backward method, in which the state variables are the node voltages. If it is weakly meshed, the network is turned into radial by means of cuts and compensation currents. After the presentation of the general problem, the equations expressing the unknowns for the PQ nodes are treated in detail. These equations belong to the backward sweep of the algorithm. The methodology has been implemented and applied so as…
A new model of PV nodes in distribution networks backward/forward analysis
2004
In this paper a new model of PV nodes is developed; the model is aimed for the distribution systems load flow analysis and, in particular, for the iterative forward/backward method. If the network is weakly meshed, it is turned into radial by means of cuts and compensation currents. After the presentation of the general problem and the state of the art on the subject, the equations expressing the unknowns for the PV nodes are treated in detail. These equations belong to the forward sweep of the algorithm. The methodology has been implemented and applied so as to test its performance in terms of calculation times and precision. The obtained results confirm the efficiency of the proposed appr…
Application to an italian distribution system of a multiobjective optimal Volt/VAR control strategy: improvements and management problems
2007
In this paper, the experiences and results deriving from the application of a multiobjective optimal management strategy to a distribution network supplying an area in province of Palermo, Italy, are presented. The adopted strategy allows, through the interventions on the Under Load Tap Changers (ULTC) of the primary substations and on tie-switches, to reduce power losses and improve the voltage profiles. To solve the optimization problem, an evolutionary approach has been adopted; it employs fuzzy logic for an adequate and simultaneous fulfilment of the different objectives. The application section presents a deep technical and economical analysis of the results attained, applying the opti…
An Adaptive Bayesian System for Context-Aware Data Fusion in Smart Environments
2017
The adoption of multi-sensor data fusion techniques is essential to effectively merge and analyze heterogeneous data collected by multiple sensors, pervasively deployed in a smart environment. Existing literature leverages contextual information in the fusion process, to increase the accuracy of inference and hence decision making in a dynamically changing environment. In this paper, we propose a context-aware, self-optimizing, adaptive system for sensor data fusion, based on a three-tier architecture. Heterogeneous data collected by sensors at the lowest tier are combined by a dynamic Bayesian network at the intermediate tier, which also integrates contextual information to refine the infe…
Real-Time Visual Grasp Synthesis Using Genetic Algorithms and Neural Networks
2007
This paper addresses the problem of automatic grasp synthesis of unknown planar objects. In other words, we must compute points on the object’s boundary to be reached by the robotic fingers such that the resulting grasp, among infinite possibilities, optimizes some given criteria. Objects to be grasped are represented as superellipses, a family of deformable 2D parametric functions. They can model a large variety of shapes occurring often in practice by changing a small number of parameters. The space of possible grasp configurations is analyzed using genetic algorithms. Several quality criteria from existing literature together with kinematical and mechanical considerations are considered.…
A possible approach to the development of robotic multi-agent systems
2004
The design of a an agent system for robotics is a problem that involves aspects coming from many different disciplines (robotics, artificial intelligence, computer vision, software engineering). The most difficult part of it, often consists in producing and tuning the algorithms that incorporates the robot behavior (planning, obstacle avoidance,. . . ) and abilities (vision, manipulation, navigation,. . . ). Frequently, the reuse of these parts is left to a copy and paste procedure from previous applications to the new one. In so doing many problems could arise. We propose a comprehensive approach for multi-agent systems oriented to robotics applications that uses a complete design methodol…
Referenceless thermometry using radial basis function interpolation
2014
The Proton Resonance Frequency (PRF) shift provide a method for temperature change measurements during thermotherapy. Conventional PRF thermometry works subtracting one or multiple baseline images. The method leads to artifacts caused by tissue motion and frequency drift. Various works estimating the background phase from each acquired image phase are present in literature. These algorithms are called “referenceless” because they don’t require any subtraction of baseline images for calculating temperature increment. Conventional referenceless methods estimate baseline image by fitting the background phase outside the heated region through a polynomial approach. In this work a background pha…
Optic disc positioning and blood vessels extraction on eye fundus
2009
This paper presents two methods aimed to the optic disc positioning on the retinal images. The first is based on a template of the entire image, while the second is based on the retinal vascularisation. For this second task, also a vessel extraction method is provided. Both the algorithm have been tested on test images of the Drive Database.