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Avaliação de algoritmos de controle de congestionamento como controle de admissão em um modelo de servidores web com diferenciação de serviços; Evaluation of congestion control algorithms used as control admission in a model of web servers with service differentiation

Figueiredo, Ricardo Nogueira de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/03/2011 PT
Relevância na Pesquisa
55.61%
Esta dissertação apresenta a construção de um protótipo de servidor Web distribuído, baseado no modelo de servidor Web com diferenciação de serviços (SWDS) e a implementação e avaliação de algoritmos de seleção, utilizando o conceito de controle de congestionamento para requisições HTTP. Com isso, além de implementar uma plataforma de testes, este trabalho também avalia o comportamento de dois algoritmos de controle de congestionamento. Os dois algoritmos estudados são chamados de Drop Tail e RED (Random Early Detection), no qual são bastante difundidos na literatura científica e aplicados em redes de computadores. Os resultados obtidos demostram que, apesar das particularidades de cada algoritmo, existe uma grande relação entre tempo de resposta e a quantidade de requisições aceitas; This MSc dissertation presents the implementation of a prototype for a distributed web server based on the SWDS, a model for a web server with service differentiation, and the implementation and evaluation of selection algorithms adopting the concept of congestion control for HTTP requests. Thus, besides implementing a test platform this work also evaluates the behavior of two congestion control algorithms. The two algorithms studied are the Drop Tail and the RED (Random Early Detection)...

Avaliação de roteamento em redes P2P visando obtenção de QoS na busca de serviço em nuvem; Evaluation of routing in P2P networks in order to obtain QoS in search of cloud service

Leite Filho, Dionisio Machado
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/04/2012 PT
Relevância na Pesquisa
55.6%
Este trabalho apresenta a avaliação de diferentes algoritmos de roteamento utilizados na camada lógica ponto a ponto (P2P) adotada por um Metaescalonador que provê Qualidade de Serviços (QoS) na Computação em Nuvem. Experimentos mostram a superioridade de três algoritmos de roteamento P2P (BCR, Chord e Pastry) em relação à utilização de Round Robin, analisando-se o tempo de resposta e a variabilidade entre os resultados obtidos em diferentes testes. Os experimentos consideram, além dos algoritmos de roteamento, a influência do número de usuários e do tipo de serviço requisitado e como esses fatores interagem entre si. É apresentado ainda um estudo sobre a melhor métrica a ser adotada para representar as informações da rede. As métricas consideradas foram latência e número de saltos. Os resultados obtidos permitem determinar, com base nos objetivos especificados, qual o impacto dos sistemas P2P utilizados pelo metaescalonador na busca e descoberta de serviços em relação à forma como a qualidade de serviços é abordada; This work presents an evaluation of different routing algorithms that are employed in a logical layer peer-to-peer (P2P) that are adopted by a Metascheduler that provides quality of services (QoS) in Cloud Computing. The experiments show the superiority of three P2P routing algorithms (BCR...

Avaliação e seleção de modelos em detecção não supervisionada de outliers; On the internal evaluation of unsupervised outlier detection

Marques, Henrique Oliveira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/03/2015 PT
Relevância na Pesquisa
55.6%
A área de detecção de outliers (ou detecção de anomalias) possui um papel fundamental na descoberta de padrões em dados que podem ser considerados excepcionais sob alguma perspectiva. Uma importante distinção se dá entre as técnicas supervisionadas e não supervisionadas. O presente trabalho enfoca as técnicas de detecção não supervisionadas. Existem dezenas de algoritmos desta categoria na literatura, porém cada um deles utiliza uma intuição própria do que deve ser considerado um outlier ou não, que é naturalmente um conceito subjetivo. Isso dificulta sensivelmente a escolha de um algoritmo em particular e também a escolha de uma configuração adequada para o algoritmo escolhido em uma dada aplicação prática. Isso também torna altamente complexo avaliar a qualidade da solução obtida por um algoritmo/configuração em particular adotados pelo analista, especialmente em função da problemática de se definir uma medida de qualidade que não seja vinculada ao próprio critério utilizado pelo algoritmo. Tais questões estão inter-relacionadas e se referem respectivamente aos problemas de seleção de modelos e avaliação (ou validação) de resultados em aprendizado de máquina não supervisionado. Neste trabalho foi desenvolvido um índice pioneiro para avaliação não supervisionada de detecção de outliers. O índice...

Evaluation of license-plate location algorithms

Sequeira, Manuel Menezes de; Brandão, Tomás; Albuquerque, Miguel
Fonte: Instituto Superior Técnico Publicador: Instituto Superior Técnico
Tipo: Conferência ou Objeto de Conferência
Publicado em /04/2004 ENG
Relevância na Pesquisa
65.73%
We propose a new evaluation method for license-plate location algorithms. As a first step towards a comparison of the algorithms described in the literature over the years, we have implemented some relevant algorithms with different approaches and compared them using the proposed evaluation method. The software used for evaluation and a set of annotated evaluation images are both readily available, making the reproduction of the presented results possible. The availability of both software and an evaluation set allows the results presented in this paper to be used as benchmarks when developing plate location algorithms.

Generalized Linear Dynamics of a Plant-Parasitic Nematode Population and the Economic Evaluation of Crop Rotations

Van Den Berg, W.; Rossing, W. A. H.
Fonte: Society of Nematologists Publicador: Society of Nematologists
Tipo: Artigo de Revista Científica
Publicado em /03/2005 EN
Relevância na Pesquisa
65.43%
In 1-year experiments, the final population density of nematodes is usually modeled as a function of initial density. Often, estimation of the parameters is precarious because nematode measurements, although laborious and expensive, are imprecise and the range in initial densities may be small. The estimation procedure can be improved by using orthogonal regression with a parameter for initial density on each experimental unit. In multi-year experiments parameters of a dynamic model can be estimated with optimization techniques like simulated annealing or Bayesian methods such as Markov chain Monte Carlo (MCMC). With these algorithms information from different experiments can be combined. In multi-year dynamic models, the stability of the steady states is an important issue. With chaotic dynamics, prediction of densities and associated economic loss will be possible only on a short timescale. In this study, a generic model was developed that describes population dynamics in crop rotations. Mathematical analysis showed stable steady states do exist for this dynamic model. Using the Metropolis algorithm, the model was fitted to data from a multi-year experiment on Pratylenchus penetrans dynamics with treatments that varied between years. For three crops...

FlyPrimerBank: An Online Database for Drosophila melanogaster Gene Expression Analysis and Knockdown Evaluation of RNAi Reagents

Hu, Yanhui; Sopko, Richelle; Foos, Marianna; Kelley, Colleen; Flockhart, Ian; Ammeux, Noemie; Wang, Xiaowei; Perkins, Lizabeth; Perrimon, Norbert; Mohr, Stephanie E.
Fonte: Genetics Society of America Publicador: Genetics Society of America
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
65.5%
The evaluation of specific endogenous transcript levels is important for understanding transcriptional regulation. More specifically, it is useful for independent confirmation of results obtained by the use of microarray analysis or RNA-seq and for evaluating RNA interference (RNAi)-mediated gene knockdown. Designing specific and effective primers for high-quality, moderate-throughput evaluation of transcript levels, i.e., quantitative, real-time PCR (qPCR), is nontrivial. To meet community needs, predefined qPCR primer pairs for mammalian genes have been designed and sequences made available, e.g., via PrimerBank. In this work, we adapted and refined the algorithms used for the mammalian PrimerBank to design 45,417 primer pairs for 13,860 Drosophila melanogaster genes, with three or more primer pairs per gene. We experimentally validated primer pairs for ~300 randomly selected genes expressed in early Drosophila embryos, using SYBR Green-based qPCR and sequence analysis of products derived from conventional PCR. All relevant information, including primer sequences, isoform specificity, spatial transcript targeting, and any available validation results and/or user feedback, is available from an online database (www.flyrnai.org/flyprimerbank). At FlyPrimerBank...

On the explanatory value of condition numbers for convex optimization : theoretical issues and computational experience

Ordóñez, Fernando, 1970-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 216 p.; 6442537 bytes; 6442344 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
65.36%
The modern theory of condition numbers for convex optimization problems was developed for convex problems in conic format: ... The condition number C(d) for (CPd) has been shown in theory to provide upper and/or lower bounds on many behavioral and computational characteristics of (CPd), from sizes of feasible and optimal solutions to the complexity of algorithms for solving (CPd). However, it is not known to what extent these bounds might be reasonably close to their actual measures of interest. One difficulty in testing the practical relevance of such theoretical bounds is that most practical problems are not presented in conic format. While it is usually easy to transform convex optimization problems into conic format, such transformations are not unique and do not maintain the original data, making this strategy somewhat irrelevant for computational testing of the theory. The purpose of this thesis is to overcome the obstacles stated above. We introduce an extension of condition number theory to include convex optimization problems not in conic form, and is thus more amenable to computational evaluation. This extension considers problems of the form: ... where P is a closed convex set, no longer required to be a cone. We extend many results of condition number theory to problems of form (GPd)...

A design tool architecture for the rapid evaluation of product design tradeoffs in an Inernet-based system modeling environment

Wronski, Jacob (Jacob Andrzej)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 122 leaves; 7040531 bytes; 7047470 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
65.43%
This thesis presents a computer-aided design tool for the rapid evaluation of design tradeoffs in an integrated product modeling environment. The goal of this work is to provide product development organizations with better means of exploring product design spaces so as to identify promising de- sign candidates early in the concept generation phase. Ultimately, such practices would streamline the product development process. The proposed design tool is made up of two key components: an optimization engine, and the Distributed Object-based Modeling Environment. This modeling environment is part of an ongoing research initiative at the Computer-Aided Design Lab. The optimization engine consists of a multi- objective evolutionary algorithm developed at the Ecole Polytechnique F6d6rale de Lausanne. The first part of this thesis provides a comprehensive survey of all topics relevant to this work. Traditional product development is discussed along with some of the challenges inherent in this process. Integrated modeling tools are surveyed. Finally, a variety of optimization methods and algorithms are discussed, along with a review of commercially available optimization packages. The second part discusses the developed design tool and the implications of this work on traditional product development. After a detailed description of the optimization algorithm...

Noise reduction algorithms and performance metrics for improving speech reception in noise by cochlear-implant users

Goldsworthy, Raymond Lee, 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 233 p.
ENG
Relevância na Pesquisa
75.62%
This thesis addresses the design and evaluation of algorithms to improve speech reception for cochlear-implant (CI) users in adverse listening environments. We develop and assess performance metrics for use in the algorithm design process; such metrics make algorithm evaluation efficient, consistent, and subject independent. One promising performance metric is the Speech Transmission Index (STI), which is well correlated with speech reception by normal-hearing listeners for additive noise and reverberation. We expect the STI will effectively predict speech reception by CI users since typical CI sound-processing strategies, like the STI, rely on the envelope signals in frequency bands spanning the speech spectrum. However, STI-based metrics have proven unsatisfactory for assessing the effects of nonlinear operations on the intelligibility of processed speech. In this work we consider modifications to the STI that account for nonlinear operations commonly found in CI sound-processing and noise reduction algorithms. We consider a number of existing speech-based STI metrics and propose novel metrics applicable to nonlinear operations. A preliminary evaluation results in the selection of three candidate metrics for extensive evaluation. In four central experiments...

On the evaluation of background subtraction algorithms without ground-truth

Sanmiguel, Juan Carlos; Martínez, José M.
Fonte: Institute of Electrical and Electronics Engineers Publicador: Institute of Electrical and Electronics Engineers
Tipo: conferenceObject; bookPart
ENG
Relevância na Pesquisa
55.63%
Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. J. C. San Miguel, and J. M. Martínez, "On the evaluation of background subtraction algorithms without ground-truth" in 2013 10th IEEE International Conference on Advanced Video and Signal Based Surveillance, 2013, 180 - 187; In video-surveillance systems, the moving object segmentation stage (commonly based on background subtraction) has to deal with several issues like noise, shadows and multimodal backgrounds. Hence, its failure is inevitable and its automatic evaluation is a desirable requirement for online analysis. In this paper, we propose a hierarchy of existing performance measures not-based on ground-truth for video object segmentation. Then, four measures based on color and motion are selected and examined in detail with different segmentation algorithms and standard test sequences for video object segmentation. Experimental results show that color-based measures perform better than motion-based measures and background multimodality heavily reduces the accuracy of all obtained evaluation results.

Comparative evaluation of stationary foreground object detection algorithms based on background subtraction techniques

Bayona Gómez, Álvaro; Sanmiguel, Juan Carlos; Martínez, José M.
Fonte: Institute of Electrical and Electronics Engineers Publicador: Institute of Electrical and Electronics Engineers
Tipo: conferenceObject; bookPart
ENG
Relevância na Pesquisa
55.6%
Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Á. Bayona, J. C. SanMiguel, and J. M. Martínez, "Comparative evaluation of stationary foreground object detection algorithms based on background subtraction techniques" in Sixth IEEE International Conference on Advanced Video and Signal Based Surveillance. AVSS 2009, p. 25 - 30; In several video surveillance applications, such as the detection of abandoned/stolen objects or parked vehicles,the detection of stationary foreground objects is a critical task. In the literature, many algorithms have been proposed that deal with the detection of stationary foreground objects, the majority of them based on background subtraction techniques. In this paper we discuss various stationary object detection approaches comparing them in typical surveillance scenarios (extracted from standard datasets). Firstly, the existing approaches based on background-subtraction are organized into categories. Then...

Efficient and accurate algorithms for the computation and inversion of the incomplete gamma function ratios

Gil Gómez, Amparo; Segura Sala, José Javier; Temme, Nico M.
Fonte: Society for Industrial and Applied Mathematics Publicador: Society for Industrial and Applied Mathematics
Tipo: info:eu-repo/semantics/article; publishedVersion
ENG
Relevância na Pesquisa
55.62%
Algorithms for the numerical evaluation of the incomplete gamma function ratios $P(a,x)=gamma(a,x)/Gamma(a)$ and $Q(a,x)=Gamma(a,x)/Gamma(a)$ are described for positive values of $a$ and $x$. Also, inversion methods are given for solving the equations $P(a,x)=p$, $Q(a,x)=q$, with $0

Trust-based design of human-guided algorithms; Trust-based design of HGAs

Thomer, Joseph L. (Joseph Louis)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 229 p.
ENG
Relevância na Pesquisa
55.61%
By combining the strengths of human and computers, Human Machine Collaborative Decision Making has been shown to generate higher quality solutions in less time than conventional computerized methods. In many cases, it is difficult to model continually changing problems and incorporate human objectives into the solution. Human-guided algorithms (HGAs) harness the power of sophisticated algorithms and computers to provide flexibility to the human decision maker to model correctly and dynamically the problem and steer the algorithm to solutions that match his/her objectives for the given problem. HGAs are designed to make the power of Operations Research accessible to problem domain experts and decision makers, and incorporate their expert knowledge into every solution. In order to appropriately utilize algorithms during a planner's decision making, HGA operators must appropriately trust the HGA and the final solution. Through the use of trust-based design (TBD), it was hypothesized that users of the HGA will gain better insight into the solution process, improve their calibration of trust, and generate superior solutions. The application of TBD requires the consideration of algorithms, solution steering methods, and displays required to best match human and computer complimentary strengths and to generate solutions that can be appropriately trusted.; (cont.) Abstract hierarchy...

A systems approach to the evaluation of Radio Frequency Identification (RFID) in the defense industry

Shah, Ronak R
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 77 p.; 5828954 bytes; 5832117 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
65.43%
Radio Frequency Identification (RFID) is a wireless technology with possible applications in the supply chain. RFID tags' fast read rates, non-line-of-sight identification and large storage capacity may revolutionize supply chains in the defense industry and commercial world. Widespread adoption of RFID will require that companies achieve a return on their investment. System interactions between the implementation decisions, costs, benefits and performance of an RFID installation makes determining the optimal RFID system difficult. This thesis enumerates the various choices which affect the return on investment and describes how each is dependent upon the others. Formulating the problem as a optimization program allows one to maximize the return on investment. A three-stage process is proposed for evaluating RFID opportunities in any complex enterprise. RFID swim lanes, a new process mapping tool, is used in order to understand the complexities of material flow through facilities. A Microsoft Excel TM tool is used to formulate the optimization for the specific facility or enterprise contemplating RFID.; (cont.) Finally, financial modeling is used in conjunction with optimization algorithms in order to determine the best course of action. In order to validate this approach...

Speeding-up Dynamic Programming with Representative Sets - An Experimental Evaluation of Algorithms for Steiner Tree on Tree Decompositions

Fafianie, Stefan; Bodlaender, Hans L.; Nederlof, Jesper
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 31/05/2013
Relevância na Pesquisa
65.59%
Dynamic programming on tree decompositions is a frequently used approach to solve otherwise intractable problems on instances of small treewidth. In recent work by Bodlaender et al., it was shown that for many connectivity problems, there exist algorithms that use time, linear in the number of vertices, and single exponential in the width of the tree decomposition that is used. The central idea is that it suffices to compute representative sets, and these can be computed efficiently with help of Gaussian elimination. In this paper, we give an experimental evaluation of this technique for the Steiner Tree problem. A comparison of the classic dynamic programming algorithm and the improved dynamic programming algorithm that employs the table reduction shows that the new approach gives significant improvements on the running time of the algorithm and the size of the tables computed by the dynamic programming algorithm, and thus that the rank based approach from Bodlaender et al. does not only give significant theoretical improvements but also is a viable approach in a practical setting, and showcases the potential of exploiting the idea of representative sets for speeding up dynamic programming algorithms.

Fast computation of the performance evaluation of biometric systems: application to multibiometric

Giot, Romain; El-Abed, Mohamad; Rosenberger, Christophe
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/02/2012
Relevância na Pesquisa
55.6%
The performance evaluation of biometric systems is a crucial step when designing and evaluating such systems. The evaluation process uses the Equal Error Rate (EER) metric proposed by the International Organization for Standardization (ISO/IEC). The EER metric is a powerful metric which allows easily comparing and evaluating biometric systems. However, the computation time of the EER is, most of the time, very intensive. In this paper, we propose a fast method which computes an approximated value of the EER. We illustrate the benefit of the proposed method on two applications: the computing of non parametric confidence intervals and the use of genetic algorithms to compute the parameters of fusion functions. Experimental results show the superiority of the proposed EER approximation method in term of computing time, and the interest of its use to reduce the learning of parameters with genetic algorithms. The proposed method opens new perspectives for the development of secure multibiometrics systems by speeding up their computation time.; Comment: Future Generation Computer Systems (2012)

Convergence Time Evaluation of Algorithms in MANETs

Patil, Annapurna P; Sambaturu, Narmada; Chunhaviriyakul, Krittaya
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 08/10/2009
Relevância na Pesquisa
65.58%
Since the advent of wireless communication, the need for mobile ad hoc networks has been growing exponentially. This has opened up a Pandoras Box of algorithms for dealing with mobile ad hoc networks, or MANETs, as they are generally referred to. Most attempts made at evaluating these algorithms so far have focused on parameters such as throughput, packet delivery ratio, overhead etc. An analysis of the convergence times of these algorithms is still an open issue. The work carried out fills this gap by evaluating the algorithms on the basis of convergence time. Algorithms for MANETs can be classified into three categories: reactive, proactive, and hybrid protocols. In this project, we compare the convergence times of representative algorithms in each category, namely Ad hoc On Demand Distance Vector (AODV) reactive, Destination Sequence Distance Vector protocol (DSDV) proactive, and Temporally Ordered Routing Algorithm (TORA) hybrid. The algorithm performances are compared by simulating them in ns2. Tcl is used to conduct the simulations, while perl is used to extract data from the simulation output and calculate convergence time. The design of the experiments carried on is documented using Unified modeling Language. Also, a user interface is created using perl...

Evaluation of digital image compression algorithms for use on lap top computers

Brower, Bernard V.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
55.71%
A technique for the evaluation of image compression algorithms was developed. This technique was then applied in the evaluation of six image compression algorithms (ARIDPCM, ISO/JPEG DCT, zonal DCT, proprietary wavelet, proprietary sub-band coding and the proprietary DCT). Of the six algorithms evaluated, the Wavelet algorithm performed the best on average in image quality at all bit rates. The JPEG DCT was concluded to be the most useful algorithm because of its performance and the advantages that come with being an international standard.

A Unified Methodology to Evaluate Supervised and Non-Supervised Classification Algorithms

Godoy Calderón,Salvador; Martínez Trinidad,José Francisco; Lazo-Cortes,Manuel S; Díaz de León Santiago,Juan Luis
Fonte: Centro de Investigación en computación, IPN Publicador: Centro de Investigación en computación, IPN
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2006 EN
Relevância na Pesquisa
65.63%
There is presently no unified methodology that allows the evaluation of supervised or non-supervised classification algorithms. Supervised problems are evaluated through quality functions while non-supervised problems are evaluated through several structural indexes. In both cases a lot of useful information remains hidden or is not considered by the evaluation method, such as the quality of the sample or the structural change generated by the classification algorithm. This work proposes a unified methodology that can be used to evaluate both type of classification problems. This new methodology yields a larger amount of information to the evaluator regarding the quality of the initial sample, when it exists, and regarding the change produced by the classification algorithm in the case of non-supervised classification problems. It also offers the added possibility of making comparative evaluations with different algorithms.

Evaluation of the spatial variation of b-value

Wesseloo,J.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2014 EN
Relevância na Pesquisa
65.46%
The estimation of the spatial variation of the b-value of the Gutenberg-Richter relationship is important for both the general interpretation of the mechanism of rock mass response and seismic hazard assessment. The interpretation of b-value as a parameter of rock mass response is discussed in this paper. The methods applied to evaluate the spatial variation of b-value and the algorithm for obtaining the magnitude of completeness and b-value for subsets of data are presented with some verification analyses. The algorithms presented enable the automation of a spatial evaluation of b-value.