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Gestão de fragmentação no desmonte de rochas; Blasting fragmentation management : an innovative approach using complexity analysis

Seccatore, Jacopo; Tomi, Giorgio Francesco Cesare de; Munaretti, Enrique; Dompieri, Maurício
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
46.854204%
Esse trabalho descreve a pesquisa sobre a aplicação de análise de complexidade para avaliar o desempenho do processo de desmonte de rocha na mineração. O ob- jetivo principal da pesquisa é o desenvolvimento de um método que permita identifi- car uma solução robusta para gerenciar a fragmentação do desmonte e para planejar o processo de forma a alcançar as metas de produtividade da britagem. A pesquisa utiliza ferramentas de análise de complexidade, introduzindo uma abordagem parti- cular de sistemas complexos inédita em mineração e em aplicações de desmonte. Os resultados alcançados indicam que a compreensão adequada das correlações entre as variáveis-chaves no desmonte traz benefícios importantes para apoiar a tomada de decisão no ambiente de alta incerteza do processo de desmonte de rocha. A busca por um sistema robusto se mostrou mais relevante do que a busca por uma solução teori- camente ótima, já que os níveis de robustez e de complexidade podem ser utilizados para comparar diferentes modelos e para medir a aderência desses modelos aos dados de campo.; The paper describes the research carried out in the application of complexity analysis in order to evaluate the performance of the rock blasting process in mining. The main objective of the research is the development of a new method to allow the identification of a robust solution for managing rock fragmentation and to plan the process so that productivity targets can be achieved. The research uses complexity analysis tools introducing a particular approach for complex system analysis in min- ing and in rock blasting. The results indicate that the proper understanding of the correlations between the key-variables in blasting provides important benefits in the decision making process in the highly uncertain environment of rock blasting. The search for a robust system has proven to be more relevant than the search for a theo- retically optimum solution...

Proposta para a estimativa da acurácia de redes geodésicas horizontais integrando análise de robustez e de covariância

Klein, Ivandro; Matsuoka, Marcelo Tomio; Monico, João Francisco Galera
Fonte: Universidade Federal do Paraná Publicador: Universidade Federal do Paraná
Tipo: Artigo de Revista Científica Formato: 525-547
Português
Relevância na Pesquisa
46.98708%
The goal of this paper is to present a methodology for quality control of horizontal geodetic networks through robustness and covariance analysis. In the proposed methodology, the positional accuracy of each point is estimated by a possible bias in their position (based on robustness analysis), in addition to its own positional precision (uncertainty) (through covariance analysis), being a measure independently from the choice of the datum. Besides presenting the theoretical development of the method, its application is demonstrated in a numerical example. The results indicate that, in general, the greater the distance of an unknown point to the control(s) point(s) of the network, the greater is the propagation of random errors on this unknown point, and the smaller the number of redundant observations around a unknown point, the greater the influence of possible (undetected) non-random errors on this point.; O objetivo deste trabalho é apresentar uma proposta para o controle de qualidade de redes geodésicas bidimensionais por meio das análises de robustez e de covariância. Na metodologia proposta, a acurácia (exatidão) posicional de cada ponto é estimada por meio de uma possível tendência posicional (via análise de robustez)...

Robustness analysis of traditional timber trusses

Vilarinho, Tiago; Neves, Luís A. C.; Branco, Jorge M.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 16/06/2011 Português
Relevância na Pesquisa
47.06798%
In the present work, the safety of existing traditional timber trusses is evaluated, with particular emphasis on the structural robustness. Traditional Portuguese timber trusses are analyzed probabilistically, using the information provided in the JCSS model code, combined with action and resistance models provided in the Eurocodes. Robustness is evaluated through introduction of a localized defect, simulating deterioration, construction error or damages. The comparison between the reliability index considering a defect and the corresponding index for an intact structure is defined as a measure of susceptibility to local damage. The reliability index is computed using Monte-Carlo simulation combined with linear elastic finite elements for different examples.; Cost Action E55 “Modelling of timber performance”.

Robustness of timber structures in seismic areas

Branco, J.M.
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Artigo de Revista Científica
Publicado em 20/06/2011 Português
Relevância na Pesquisa
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Some of the properties sought in seismic design of buildings are also considered fundamental to guarantee structural robustness. Moreover, some key concepts are common to both seismic and robustness design. In fact, both analyses consider events with a very small probability of occurrence, and consequently, a significant level of damage is admissible. As very rare events,in both cases, the actions are extremely hard to quantify. The acceptance of limited damage requires a system based analysis of structures, rather than an element by element methodology, as employed for other load cases. As for robustness analysis, in seismic design the main objective is to guarantee that the structure survives an earthquake, without extensive damage. In the case of seismic design, this is achieved by guaranteeing the dissipation of energy through plastic hinges distributed in the structure. For this to be possible, some key properties must be assured, in particular ductility and redundancy. The same properties could be fundamental in robustness design, as a structure can only sustain significant damage if capable of distributing stresses to parts of the structure unaffected by the triggering event. Timber is often used for primary load‐bearing elements in single storey long‐span structures for public buildings and arenas...

Robustness analysis of deteriorating reinforced concrete slabs

Cavaco, Eduardo S.; Neves, Luis A. C.; Gonçalves, Rui C.; Casas, Joan R.
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 Português
Relevância na Pesquisa
46.993325%
Corrosion of reinforcement bars in concrete structures is the most significant deterioration mechanism in these structures. Corrosion is extremely difficult to predict and, consequently, can be regarded as an unpredictable event. Following this, robustness assessment methods can be employed to define the susceptibility of a structure to corrosion. In this work, robustness is measured in terms of the remaining safety of a deteriorated structure. The proposed methodology is illustrated by means of a reinforced concrete (RC) slab subjected to dead and live loads. The performance of the corroded slab is evaluated using non-linear analysis. The reliability index is adopted to assess the safety of the deteriorated structure. To compute the reliability index a strategy combining the First Order Reliability Method (FORM) and the Response Surface Method (RSM) is used.

The use of robustness analysis for planning actions in a poor Brazilian community

Namen,Anderson Amendoeira; Bornstein,Cláudio Thomás; Rosenhead,Jonathan
Fonte: Sociedade Brasileira de Pesquisa Operacional Publicador: Sociedade Brasileira de Pesquisa Operacional
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2010 Português
Relevância na Pesquisa
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This paper reports on the use of Robustness Analysis for planning actions in a poor Brazilian community. The focus is on food and agricultural production and the project is based on a participatory approach incorporating both community-driven development and sustainability in food production. A comparison is made with other soft Operations Research (OR) methodologies and first actions and results are reported.

Robustness Analysis and Behavior Discrimination in Enzymatic Reaction Networks

Donzé, Alexandre; Fanchon, Eric; Gattepaille, Lucie Martine; Maler, Oded; Tracqui, Philippe
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 27/09/2011 Português
Relevância na Pesquisa
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Characterizing the behavior and robustness of enzymatic networks with numerous variables and unknown parameter values is a major challenge in biology, especially when some enzymes have counter-intuitive properties or switch-like behavior between activation and inhibition. In this paper, we propose new methodological and tool-supported contributions, based on the intuitive formalism of temporal logic, to express in a rigorous manner arbitrarily complex dynamical properties. Our multi-step analysis allows efficient sampling of the parameter space in order to define feasible regions in which the model exhibits imposed or experimentally observed behaviors. In a first step, an algorithmic methodology involving sensitivity analysis is conducted to determine bifurcation thresholds for a limited number of model parameters or initial conditions. In a second step, this boundary detection is supplemented by a global robustness analysis, based on quasi-Monte Carlo approach that takes into account all model parameters. We apply this method to a well-documented enzymatic reaction network describing collagen proteolysis by matrix metalloproteinase MMP2 and membrane type 1 metalloproteinase (MT1-MMP) in the presence of tissue inhibitor of metalloproteinase TIMP2. For this model...

The Robustness Analysis of Wireless Sensor Networks under Uncertain Interference

Deng, Changjian
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 30/11/2013 Português
Relevância na Pesquisa
46.883125%
Based on the complex network theory, robustness analysis of condition monitoring wireless sensor network under uncertain interference is present. In the evolution of the topology of sensor networks, the density weighted algebraic connectivity is taken into account, and the phenomenon of removing and repairing the link and node in the network is discussed. Numerical simulation is conducted to explore algebraic connectivity characteristics and network robustness performance. It is found that nodes density has the effect on algebraic connectivity distribution in the random graph model; high density nodes carry more connections, use more throughputs, and may be more unreliable. Moreover, the results show that, when network should be more error tolerant or robust by repairing nodes or adding new nodes, the network should be better clustered in median and high scale wireless sensor networks and be meshing topology in small scale networks.

Robustness Analysis of Stochastic Biochemical Systems

Česka, Milan; Šafránek, David; Dražan, Sven; Brim, Luboš
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 21/04/2014 Português
Relevância na Pesquisa
47.18625%
We propose a new framework for rigorous robustness analysis of stochastic biochemical systems that is based on probabilistic model checking techniques. We adapt the general definition of robustness introduced by Kitano to the class of stochastic systems modelled as continuous time Markov Chains in order to extensively analyse and compare robustness of biological models with uncertain parameters. The framework utilises novel computational methods that enable to effectively evaluate the robustness of models with respect to quantitative temporal properties and parameters such as reaction rate constants and initial conditions. We have applied the framework to gene regulation as an example of a central biological mechanism where intrinsic and extrinsic stochasticity plays crucial role due to low numbers of DNA and RNA molecules. Using our methods we have obtained a comprehensive and precise analysis of stochastic dynamics under parameter uncertainty. Furthermore, we apply our framework to compare several variants of two-component signalling networks from the perspective of robustness with respect to intrinsic noise caused by low populations of signalling components. We have successfully extended previous studies performed on deterministic models (ODE) and showed that stochasticity may significantly affect obtained predictions. Our case studies demonstrate that the framework can provide deeper insight into the role of key parameters in maintaining the system functionality and thus it significantly contributes to formal methods in computational systems biology.

Efficient computational methods for robustness analysis

Kao, Chung-Yao, 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 215 p.; 7816641 bytes; 7816448 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
47.41961%
Issues of robust stability and performance have dominated the field of systems and control theory because of their practical importance. The recently developed Integral Quadratic Constraint (IQC) based analysis method provides a framework for systematically checking robustness properties of large complex dynamical systems. In IQC analysis, the system to be analyzed is represented as a nominal, Linear Time-Invariant (LTI) subsystem interconnected with a perturbation term. The perturbation is characterized in terms of IQCs. The robustness condition is expressed as a feasibility problem which can be solved using interiorpoint algorithms. Although the systems to be analyzed have nominal LTI subsystems in many applications, this is not always the case. A typical example is the problem of robustness analysis of the oscillatory behavior of nonlinear systems, where the nominal subsystem is generally Linear Periodically Time-Varying (LPTV). The objective of the first part of this thesis is to develop new techniques for robustness analysis of LPTV systems. Two different approaches are proposed. In the first approach, the harmonic terms of the LPTV nominal model are extracted, and the system is transformed into the standard setup for robustness analysis. Robustness analysis is then performed on the transformed system based on the IQC analysis method. In the second approach...

Robustness analysis of geodetic networks in the case of correlated observations

Yetkin,Mevlut; Berber,Mustafa; Inal,Cevat
Fonte: Universidade Federal do Paraná Publicador: Universidade Federal do Paraná
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2013 Português
Relevância na Pesquisa
57.097285%
GPS (or GNSS) networks are invaluable tools for monitoring natural hazards such as earthquakes. However, blunders in GPS observations may be mistakenly interpreted as deformation. Therefore, robust networks are needed in deformation monitoring using GPS networks. Robustness analysis is a natural merger of reliability and strain and defined as the ability to resist deformations caused by the maximum undetecle errors as determined from internal reliability analysis. However, to obtain rigorously correct results; the correlations among the observations must be considered while computing maximum undetectable errors. Therefore, we propose to use the normalized reliability numbers instead of redundancy numbers (Baarda's approach) in robustness analysis of a GPS network. A simple mathematical relation showing the ratio between uncorrelated and correlated cases for maximum undetectable error is derived. The same ratio is also valid for the displacements. Numerical results show that if correlations among observations are ignored, dramatically different displacements can be obtained depending on the size of multiple correlation coefficients. Furthermore, when normalized reliability numbers are small, displacements get large, i.e., observations with low reliability numbers cause bigger displacements compared to observations with high reliability numbers.

Performance and Robustness Analysis of Stochastic Jump Linear Systems using Wasserstein metric

Lee, Kooktae; Halder, Abhishek; Bhattacharya, Raktim
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.097285%
This paper focuses on the performance and the robustness analysis of stochastic jump linear systems. The state trajectory under stochastic jump process becomes random variables, which brings forth the probability distributions in the system state. Therefore, we need to adopt a proper metric to measure the system performance with respect to stochastic switching. In this perspective, Wasserstein metric that assesses the distance between probability density functions is applied to provide the performance and the robustness analysis. Both the transient and steady-state performance of the systems with given initial state uncertainties can be measured in this framework. Also, we prove that the convergence of this metric implies the mean square stability. Overall, this study provides a unifying framework for the performance and the robustness analysis of general stochastic jump linear systems, but not necessarily Markovian jump process that is commonly used for stochastic switching. The practical usefulness and efficiency of the proposed method are verified through numerical examples.

Fast Universal Algorithms for Robustness Analysis

Chen, Xinjia; Zhou, Kemin; Aravena, Jorge L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/05/2008 Português
Relevância na Pesquisa
47.28457%
In this paper, we develop efficient randomized algorithms for estimating probabilistic robustness margin and constructing robustness degradation curve for uncertain dynamic systems. One remarkable feature of these algorithms is their universal applicability to robustness analysis problems with arbitrary robustness requirements and uncertainty bounding set. In contrast to existing probabilistic methods, our approach does not depend on the feasibility of computing deterministic robustness margin. We have developed efficient methods such as probabilistic comparison, probabilistic bisection and backward iteration to facilitate the computation. In particular, confidence interval for binomial random variables has been frequently used in the estimation of probabilistic robustness margin and in the accuracy evaluation of estimating robustness degradation function. Motivated by the importance of fast computing of binomial confidence interval in the context of probabilistic robustness analysis, we have derived an explicit formula for constructing the confidence interval of binomial parameter with guaranteed coverage probability. The formula overcomes the limitation of normal approximation which is asymptotic in nature and thus inevitably introduce unknown errors in applications. Moreover...

Hierarchical Network Structure Promotes Dynamical Robustness

Smith, Cameron; Puzio, Raymond S.; Bergman, Aviv
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.06798%
The relationship between network topology and system dynamics has significant implications for unifying our understanding of the interplay among metabolic, gene-regulatory, and ecosystem network architecures. Here we analyze the stability and robustness of a large class of dynamics on such networks. We determine the probability distribution of robustness as a function of network topology and show that robustness is classified by the number of links between modules of the network. We also demonstrate that permutation of these modules is a fundamental symmetry of dynamical robustness. Analysis of these findings leads to the conclusion that the most robust systems have the most hierarchical structure. This relationship provides a means by which evolutionary selection for a purely dynamical phenomenon may shape network architectures across scales of the biological hierarchy.; Comment: 23 pages, 9 figures, 2 tables

Robustness Analysis for Value-Freezing Signal Temporal Logic

Brim, L.; Vejpustek, T.; Šafránek, D.; Fabriková, J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/09/2013 Português
Relevância na Pesquisa
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In our previous work we have introduced the logic STL*, an extension of Signal Temporal Logic (STL) that allows value freezing. In this paper, we define robustness measures for STL* by adapting the robustness measures previously introduced for Metric Temporal Logic (MTL). Furthermore, we present an algorithm for STL* robustness computation, which is implemented in the tool Parasim. Application of STL* robustness analysis is demonstrated on case studies.; Comment: In Proceedings HSB 2013, arXiv:1308.5724

On Robustness Analysis of Stochastic Biochemical Systems by Probabilistic Model Checking

Brim, Lubos; Ceska, Milan; Drazan, Sven; Safranek, David
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/10/2013 Português
Relevância na Pesquisa
57.225854%
This report proposes a novel framework for a rigorous robustness analysis of stochastic biochemical systems. The technique is based on probabilistic model checking. We adapt the general definition of robustness introduced by Kitano to the class of stochastic systems modelled as continuous time Markov Chains in order to extensively analyse and compare robustness of biological models with uncertain parameters. The framework utilises novel computational methods that enable to effectively evaluate the robustness of models with respect to quantitative temporal properties and parameters such as reaction rate constants and initial conditions. The framework is applied to gene regulation as an example of a central biological mechanism where intrinsic and extrinsic stochasticity plays crucial role due to low numbers of DNA and RNA molecules. Using our methods we have obtained a comprehensive and precise analysis of stochastic dynamics under parameter uncertainty. Furthermore, we apply our framework to compare several variants of two-component signalling networks from the perspective of robustness with respect to intrinsic noise caused by low populations of signalling components. We succeeded to extend previous studies performed on deterministic models (ODE) and show that stochasticity may significantly affect obtained predictions. Our case studies demonstrate that the framework can provide deeper insight into the role of key parameters in maintaining the system functionality and thus it significantly contributes to formal methods in computational systems biology.; Comment: 43 pages...

Probabilistic Robustness Analysis -- Risks, Complexity and Algorithms

Chen, Xinjia; Zhou, Kemin; Aravena, Jorge L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/07/2007 Português
Relevância na Pesquisa
46.883125%
It is becoming increasingly apparent that probabilistic approaches can overcome conservatism and computational complexity of the classical worst-case deterministic framework and may lead to designs that are actually safer. In this paper we argue that a comprehensive probabilistic robustness analysis requires a detailed evaluation of the robustness function and we show that such evaluation can be performed with essentially any desired accuracy and confidence using algorithms with complexity linear in the dimension of the uncertainty space. Moreover, we show that the average memory requirements of such algorithms are absolutely bounded and well within the capabilities of today's computers. In addition to efficiency, our approach permits control over statistical sampling error and the error due to discretization of the uncertainty radius. For a specific level of tolerance of the discretization error, our techniques provide an efficiency improvement upon conventional methods which is inversely proportional to the accuracy level; i.e., our algorithms get better as the demands for accuracy increase.; Comment: 28 pages, 5 figures

Robustness Analysis of Hottopixx, a Linear Programming Model for Factoring Nonnegative Matrices

Gillis, Nicolas
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
56.7684%
Although nonnegative matrix factorization (NMF) is NP-hard in general, it has been shown very recently that it is tractable under the assumption that the input nonnegative data matrix is close to being separable (separability requires that all columns of the input matrix belongs to the cone spanned by a small subset of these columns). Since then, several algorithms have been designed to handle this subclass of NMF problems. In particular, Bittorf, Recht, R\'e and Tropp (`Factoring nonnegative matrices with linear programs', NIPS 2012) proposed a linear programming model, referred to as Hottopixx. In this paper, we provide a new and more general robustness analysis of their method. In particular, we design a provably more robust variant using a post-processing strategy which allows us to deal with duplicates and near duplicates in the dataset.; Comment: 23 pages; new numerical results; Comparison with Arora et al.; Accepted in SIAM J. Mat. Anal. Appl

A State-Space Approach to Robustness Analysis and Synthesis for Nonlinear Uncertain Systems

Lu, Wei-Min; Doyle, John C.
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/pdf; application/postscript
Publicado em 12/05/1994 Português
Relevância na Pesquisa
46.94748%
A state-space characterization of stability and performance robustness analysis and synthesis with some computationally attractive properties for nonlinear uncertain systems is proposed. The robust stability and robust performances for a class of nonlinear systems subject to bounded structured uncertainties are characterized in terms of various types of nonlinear matrix inequalities (NLMIs), which are natural generalizations of the linear matrix inequalities (LMIs) that appear in linear robustness analysis. As in the linear case, scalings or multipliers are used to find storage functions that give sufficient conditions for robust performances; these are also necessary under certain assumptions about smoothness of the storage functions and structure of the uncertainty. The resulting NLMIs yield convex optimization problems. Unlike the linear case, these convex problems are not finite dimensional, so their computational benefits are far less immediate. Sufficient conditions for the solvability of robust synthesis problems are developed in terms of NLMIs as well. Some aspects of the computational issues are also discussed.

ROBUSTNESS ANALYSIS OF GEODETIC NETWORKS IN THE CASE OF CORRELATED OBSERVATIONS

YETKIN, MEVLUT; UFPR; BERBER, MUSTAFA; Florida Atlantic University; INAL, CEVAT; Selcuk University
Fonte: Universidade Federal do Paraná-UFPR Publicador: Universidade Federal do Paraná-UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 11/09/2013 Português
Relevância na Pesquisa
57.097285%
GPS (or GNSS) networks are invaluable tools for monitoring natural hazards such as earthquakes. However, blunders in GPS observations may be mistakenly interpreted as deformation. Therefore, robust networks are needed in deformation monitoring using GPS networks. Robustness analysis is a natural merger of reliability and strain and defined as the ability to resist deformations caused by the maximum undetectable errors as determined from internal reliability analysis. However, to obtain rigorously correct results; the correlations among the observations must be considered while computing maximum undetectable errors. Therefore, we propose to use the normalized reliability numbers instead of redundancy numbers (Baarda’s approach) in robustness analysis of a GPS network. A simple mathematical relation showing the ratio between uncorrelated and correlated cases for maximum undetectable error is derived. The same ratio is also valid for the displacements. Numerical results show that if correlations among observations are ignored, dramatically different displacements can be obtained depending on the size of multiple correlation coefficients. Furthermore, when normalized reliability numbers are small, displacements get large, i.e., observations with low reliability numbers cause bigger displacements compared to observations with high reliability numbers.