Search results for "A* algorithm"
showing 10 items of 2538 documents
A Peer-to-Peer Market Algorithm for a Blockchain Platform
2020
In an era of technological revolution in which everything becomes smarter and connected, the blockchain can introduce a new model for energy transactions able to grant more simplicity, security and transparency for end-users. The blockchain technology is characterized by a distributed architecture without a trusted and centralized authority, and, therefore, it appears as the perfect solutions for managing exchanges between peers. In this paper, a market algorithm that can be easily transferred to a smart contract for maximizing the match between produced and consumed energy in a micro-grid is presented. The algorithm supports energy transactions between peers (both producers and consumers) …
Convergence Analysis of Distributed Set-Valued Information Systems
2016
This paper focuses on the convergence of information in distributed systems of agents communicating over a network. The information on which the convergence is sought is not rep- resented by real numbers, as often in the literature, rather by sets. The dynamics of the evolution of information across the net- work is accordingly described by set-valued iterative maps. While the study of convergence of set-valued iterative maps is highly complex in general, this paper focuses on Boolean maps, which are comprised of arbitrary combinations of unions, intersections, and complements of sets. For these important class of systems, we provide tools to study both global and local convergence. A distr…
Brachytherapy heterogeneity correction algorithm
2011
El objetivo de este trabajo de investigación es el estudio de la influencia de heterogeneidades de los tejidos en la dosimetría de braquiterapia. En concreto, hemos desarrollado un algoritmo que tiene en cuenta las calcificaciones localizadas dentro de la próstata y corrige la dosis de referencia en agua. Este algoritmo está basado en un modelo analítico y es aplicable a Sistemas de Planificación del Tratamiento (TPS) comerciales. El modelo analítico tiene un fundamento teórico consistente, y se basa en los valores de referencia (caso homogéneo) y en la definición de una longitud efectiva, que transforma el recorrido dentro de la calcificación en distancias mayores. La energía depositada en…
A branch-and-cut algorithm for the Team Orienteering Problem
2017
The Team Orienteering Problem aims at maximizing the total amount of profit collected by a fleet of vehicles while not exceeding a predefined travel time limit on each vehicle. In the last years, several exact methods based on different mathematical formulations were proposed. In this paper, we present a new two-index formulation with a polynomial number of variables and constraints. This compact formulation, reinforced by connectivity constraints, was solved by means of a branch-and-cut algorithm. The total number of instances solved to optimality is 327 of 387 benchmark instances, 26 more than any previous method. Moreover, 24 not previously solved instances were closed to optimality.
Fast 3D Ray Tracing for Indoor Coverage Solutions
2016
Optimal wireless indoor network planning requires huge number of iterations and evaluations of indoor coverage for each antenna location until an optimal solution is reached. Consequently, accurate and scalable calculation of power strength for indoor scenarios becomes necessary. The contribution in this paper is to reduce the complexity of 3D ray tracing for deterministic indoor power prediction. In order to achieve that while preserving the accuracy, image theory with feasible reflection volume as preprocessing approach is introduced. This proposed algorithm stores the image, its feasible reflection volume and valid area of receiving points. Significant complexity reduction is achieved by…
Parallel distance transforms on pyramid machines: Theory and implementation
1990
Abstract A distance transform of a binary image is an array each of whose elements gives the distance from the corresponding pixel to the closest ‘1’ in the binary image. Distance transforms have uses in image matching and shape analysis, among other applications. We present a parallel algorithm for weighted distance transforms that runs particularly efficiently on hierarchical cellular-logic machines, a subclass of the architectures known as pyramid machines. The algorithm computes the 3–4 distance transform; however it can be readily adapted to the city-block (‘Manhattan’) and chessboard distance measures. The algorithm runs in O(M) time, for an M × M image. Since it avoids using arithmet…
Optimization of the Relay Selection Scheme in Cooperative Retransmission Networks
2011
Cooperative MAC protocol design has attracted much attention recently thanks to the development of relaying techniques. In single-relay C-ARQ, the relay selection scheme cannot work efficiently in a dense network, due to high collision probability among different contending relays. In this paper, the throughput performance impairment from the collision is analysed in a typical network scenario. Thereby, we propose an optimized relay selection scheme aiming at maximizing system throughput by reducing collision probability. The throughput performance enhancement by the proposed optimal relay selection scheme is verified by simulations.
Optimization of a Time-to-Digital Converter and a coincidence map algorithm for TOF-PET applications
2015
This contribution describes the optimization of a multichannel high resolution Time-to-Digital Converter (TDC) in a Field-Programmable Gate Array (FPGA) initially capable of obtaining time resolutions below 100ps for multiple channels. Due to its fast propagation capability it has taken advantage of the FPGA internal carry logic for accurate time measurements. Furthermore, the implementation of the TDC has been performed in different clock regions and tested with different frequencies as well, achieving improvements of up to 50% for a pair of channels. Moreover, since the TDC is potentially going to be used in a trigger system for Positron Emission Tomography (PET), the algorithm for coinci…
Experimental evaluation of topological-based fitness functions to detect complexes in PPI networks
2012
The detection of groups of proteins sharing common biological features is an important research issue, intensively investigated in the last few years, because of the insights it can give in understanding cell behavior. In this paper we present an extensive experimental evaluation campaign aiming at exploring the capability of Genetic Algorithms (GAs) to find clusters in protein-protein interaction networks, when different topological-based fitness functions are employed. A complete experimentation on the yeast protein-protein interaction network, along with a comparative evaluation of the effectiveness in detecting true complexes on the yeast and human networks, reveals GAs as a feasible an…
Embedded Real-Time Surveillance Using Multimodal Mean Background Modeling
2008
Automated video surveillance applications require accurate separation of foreground and background image content. Cost-sensitive embedded platforms place real-time performance and efficiency demands on techniques to accomplish this task. In this chapter, we evaluate pixel-level foreground extraction techniques for a low-cost integrated surveillance system. We introduce a new adaptive background modeling technique, multimodal mean (MM), which balances accuracy, performance, and efficiency to meet embedded system requirements. Our evaluation compares several pixel-level foreground extraction techniques in terms of their computation and storage requirements, and functional accuracy for three r…