Kamal Premaratne | University of Miami (original) (raw)

Papers by Kamal Premaratne

Research paper thumbnail of An analytical framework for soft and hard data fusion: a dempster-shafer belief theoretic approach

The recent experiences of asymmetric urban military operations have highlighted the pressing need... more The recent experiences of asymmetric urban military operations have highlighted the pressing need for incorporation of soft data, such as informant statements, into the fusion process. Soft data are fundamentally different from hard data (generated by physics-based sensors), in the sense that the information they provide tends to be qualitative and subject to interpretation. These characteristics pose a major obstacle to using existing multi-sensor data fusion frameworks, which are quite well established for hard data. Given the critical and sensitive nature of intended applications, soft/hard data fusion requires a framework that allows for convenient representation of various data uncertainties common in soft/hard data, and provides fusion techniques that are robust, mathematically justifiable, and yet effective. This would allow an analyst to make decisions with a better understanding of the associated uncertainties as well as the fusion mechanism itself. We present here a detailed account of an analytical solution to the task of soft/hard data fusion. The developed analytical framework consists of several main components: (i) a Dempster-Shafer (DS) belief theory based fusion strategy, (ii) a complete characterization of the Fagin-Halpern DS theoretic (DST) conditional notion which forms the basis of the data fusion framework, (iii) an evidence updating strategy for the purpose of consensus generation, (iv) a credibility estimation technique for validation of evidence, and (v) techniques for reducing computational burden associated with the proposed fusion framework. The proposed fusion strategy possesses several intuitively appealing features, and satisfies certain algebraic and fusion properties making it particularly useful in a soft/hard fusion environment. This strategy is based on DS belief theory which allows for convenient representation of uncertainties that are typical of soft/hard domains. The Fagin-Halpern (FH) notion is perhaps the most appropriate DST conditional notion for soft/hard data fusion scenarios. It also forms the basis for our fusion framework. We provide a complete characterization of the FH conditional notion. This constitutes a strong result, that sets the foundation for understanding the FH conditional notions and also establishes the theoretical grounds for development of algorithms for efficient computation of FH conditionals. We also address the converse problem of determining the evidence that may have generated a given change of belief. This converse result can be of significant practical value in certain applications. A consensus control strategy developed based on our fusion technique allows consensus analysis to be carried out in a multitude of applications that call for extended flexibility in uncertainty modeling. We provide a complete theoretical development of the proposed consensus strategy with rigorous proofs. We make use of these consensus notions to establish a data validation technique to assess credibility of evidence in the absence of ground truth. Credibility estimates can be used in fusion equations and also be used to estimate reliability of sources for subsequent fusion operations. Computational overhead is one of the major obstacles associated with data fusion operations, especially in DS theoretic methods. We propose a graphical procedure and its associated message passing scheme for efficient computation of the conditionals, along with the theoretical bounds for computational costs. In addition, we propose a method based on statistical sampling techniques to approximate DST data models. This allows for efficient computational representations as well as further reductions in computational costs associated with DS theoretic fusion operations. We have used several example scenarios throughout the presentation to clarify and validate the proposed notions and techniques. We conclude the dissertation by providing severalguidelines for future research and summary of the work that is being presented.

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Research paper thumbnail of Discrete-time positive-real lemma revisited: the discrete-time counterpart of the Kalman-Yakubovitch lemma

IEEE transactions on circuits and systems, 1994

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Research paper thumbnail of Model reduction of two-dimensional discrete systems

IEEE Transactions on Circuits and Systems, May 1, 1986

In this paper the one-dimensional (1-D) reduction method of Badreddin-Mansour is extended to two-... more In this paper the one-dimensional (1-D) reduction method of Badreddin-Mansour is extended to two-dimensional (2-D) discrete systems. It is found by counterexample that contrary to the 1-D case, stability is not guaranteed, for the reduced model, in general. However, stability is guaranteed for the reduced model if the original system is stable, in the following two cases: (1) the original

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Research paper thumbnail of On the Bistritz tabular form and its relationship with the Schur-Cohn minors and inner determinants

Journal of The Franklin Institute-engineering and Applied Mathematics, 1993

Abstract The Bistritz tabular form may be utilized in determining discrete-time system stability ... more Abstract The Bistritz tabular form may be utilized in determining discrete-time system stability with less computational effort as compared with the Jury tabular form. When appropriately constructed, the latter, however, provides the Schur-Cohn minors and the inner determinants related to the characteristic equation being tested. In this paper, we show that these quantities also may be extracted from the Bistritz tabular form. The cases of polynomials with both real- and complex-valued coefficients are studied. An important consequence of these relationships is the possibility of utilizing the Bistritz table in determining stability of two- and multi-dimensional discrete-time systems

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Research paper thumbnail of Delta-operator formulated discrete-time approximations of continuous-time systems

IEEE Transactions on Automatic Control, Mar 1, 1994

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Research paper thumbnail of Why do people believe COVID-19 conspiracy theories?

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Research paper thumbnail of Clustering Edges in Directed Graphs

arXiv (Cornell University), Feb 23, 2022

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Research paper thumbnail of Supplementary materials to: Do conspiracy beliefs form a belief system? Examining the structure and organization of conspiracy beliefs

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Research paper thumbnail of <title>Single-input/multi-output strategies for floor vibration control</title>

Proceedings of SPIE, Apr 20, 2000

ABSTRACT

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Research paper thumbnail of Rule mining and missing-Value prediction in the presence of data ambiguities

The success of knowledge discovery in real-world domains often depends on our ability to handle d... more The success of knowledge discovery in real-world domains often depends on our ability to handle data imperfections. Here we study this problem in the framework of association mining, seeking to identify frequent itemsets in transactional databases where the presence of some items in a given transaction is unknown. We want to use the frequent itemsets to predict "missing items": based on the partial contents of a shopping cart, predict what else will be added. We describe a technique that addresses this task, and report experiments illustrating its behavior.

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Research paper thumbnail of Linear time and space algorithm for computing all the fagin-halpern conditional beliefs generated from consonant belief functions

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Research paper thumbnail of Resource management of task oriented distributed sensor networks

In this paper we provide a foundation for a unified analysis of both the decision fusion and cong... more In this paper we provide a foundation for a unified analysis of both the decision fusion and congestion avoidance aspects of a task-oriented distributed sensor network (DSN). Such a framework allows network resource management to be carried out in a manner that is sensitive to the overall objectives of the DSN rather than decoupling them via perhaps simple fairness strategies.

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Research paper thumbnail of Uncertain Logic Processing: logic-based inference and reasoning using Dempster–Shafer models

International Journal of Approximate Reasoning, Apr 1, 2018

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Research paper thumbnail of Consensus in the Presence of Multiple Opinion Leaders: Effect of Bounded Confidence

IEEE Transactions on Signal and Information Processing over Networks, Sep 1, 2016

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Research paper thumbnail of A distributed congestion and power control algorithm to achieve bounded average queuing delay in wireless networks

Telecommunication Systems, Jan 13, 2010

Allocating limited resources such as bandwidth and power in a multi-hop wireless network can be f... more Allocating limited resources such as bandwidth and power in a multi-hop wireless network can be formulated as a Network Utility Maximization (NUM) problem. In this approach, both transmitting source nodes and relaying link nodes exchange information allowing for the NUM problem to be solved in an iterative distributed manner. Some previous NUM formulations of wireless network problems have considered the

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Research paper thumbnail of Dynamics of Consensus Formation among Agent Opinions

CRC Press eBooks, Dec 19, 2017

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Research paper thumbnail of Efficient sensor selection with application to time varying graphs

This paper addresses the problem of efficiently selecting sensors such that the mean squared esti... more This paper addresses the problem of efficiently selecting sensors such that the mean squared estimation error is minimized under jointly Gaussian assumptions. First, we propose an O(n3) algorithm that yields the same set of sensors as a previously published near mean squared error (MSE) optimal method that runs in O(n4). Then we show that this approach can be extended to efficient sensor selection in a time varying graph. We consider a rank one modification to the graph Laplacian, which captures the cases where a new edge is added or deleted, or an edge weight is changed, for a fixed set of vertices. We show that we can efficiently update the new set of sensors in O(n2) time for the best case by saving computations that were done for the original graph. Experiments demonstrate advantages in computational time and MSE accuracy in the proposed methods compared to recently developed graph sampling methods.

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Research paper thumbnail of Who Supports QAnon? A Case Study in Political Extremism

The Journal of Politics, Jul 1, 2022

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Research paper thumbnail of A necessary and sufficient condition for robust asymptotic stability of time-variant discrete systems

IEEE Transactions on Automatic Control, 1993

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Research paper thumbnail of The psychological and political correlates of conspiracy theory beliefs

Scientific Reports, Dec 15, 2022

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Research paper thumbnail of An analytical framework for soft and hard data fusion: a dempster-shafer belief theoretic approach

The recent experiences of asymmetric urban military operations have highlighted the pressing need... more The recent experiences of asymmetric urban military operations have highlighted the pressing need for incorporation of soft data, such as informant statements, into the fusion process. Soft data are fundamentally different from hard data (generated by physics-based sensors), in the sense that the information they provide tends to be qualitative and subject to interpretation. These characteristics pose a major obstacle to using existing multi-sensor data fusion frameworks, which are quite well established for hard data. Given the critical and sensitive nature of intended applications, soft/hard data fusion requires a framework that allows for convenient representation of various data uncertainties common in soft/hard data, and provides fusion techniques that are robust, mathematically justifiable, and yet effective. This would allow an analyst to make decisions with a better understanding of the associated uncertainties as well as the fusion mechanism itself. We present here a detailed account of an analytical solution to the task of soft/hard data fusion. The developed analytical framework consists of several main components: (i) a Dempster-Shafer (DS) belief theory based fusion strategy, (ii) a complete characterization of the Fagin-Halpern DS theoretic (DST) conditional notion which forms the basis of the data fusion framework, (iii) an evidence updating strategy for the purpose of consensus generation, (iv) a credibility estimation technique for validation of evidence, and (v) techniques for reducing computational burden associated with the proposed fusion framework. The proposed fusion strategy possesses several intuitively appealing features, and satisfies certain algebraic and fusion properties making it particularly useful in a soft/hard fusion environment. This strategy is based on DS belief theory which allows for convenient representation of uncertainties that are typical of soft/hard domains. The Fagin-Halpern (FH) notion is perhaps the most appropriate DST conditional notion for soft/hard data fusion scenarios. It also forms the basis for our fusion framework. We provide a complete characterization of the FH conditional notion. This constitutes a strong result, that sets the foundation for understanding the FH conditional notions and also establishes the theoretical grounds for development of algorithms for efficient computation of FH conditionals. We also address the converse problem of determining the evidence that may have generated a given change of belief. This converse result can be of significant practical value in certain applications. A consensus control strategy developed based on our fusion technique allows consensus analysis to be carried out in a multitude of applications that call for extended flexibility in uncertainty modeling. We provide a complete theoretical development of the proposed consensus strategy with rigorous proofs. We make use of these consensus notions to establish a data validation technique to assess credibility of evidence in the absence of ground truth. Credibility estimates can be used in fusion equations and also be used to estimate reliability of sources for subsequent fusion operations. Computational overhead is one of the major obstacles associated with data fusion operations, especially in DS theoretic methods. We propose a graphical procedure and its associated message passing scheme for efficient computation of the conditionals, along with the theoretical bounds for computational costs. In addition, we propose a method based on statistical sampling techniques to approximate DST data models. This allows for efficient computational representations as well as further reductions in computational costs associated with DS theoretic fusion operations. We have used several example scenarios throughout the presentation to clarify and validate the proposed notions and techniques. We conclude the dissertation by providing severalguidelines for future research and summary of the work that is being presented.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Discrete-time positive-real lemma revisited: the discrete-time counterpart of the Kalman-Yakubovitch lemma

IEEE transactions on circuits and systems, 1994

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Model reduction of two-dimensional discrete systems

IEEE Transactions on Circuits and Systems, May 1, 1986

In this paper the one-dimensional (1-D) reduction method of Badreddin-Mansour is extended to two-... more In this paper the one-dimensional (1-D) reduction method of Badreddin-Mansour is extended to two-dimensional (2-D) discrete systems. It is found by counterexample that contrary to the 1-D case, stability is not guaranteed, for the reduced model, in general. However, stability is guaranteed for the reduced model if the original system is stable, in the following two cases: (1) the original

Bookmarks Related papers MentionsView impact

Research paper thumbnail of On the Bistritz tabular form and its relationship with the Schur-Cohn minors and inner determinants

Journal of The Franklin Institute-engineering and Applied Mathematics, 1993

Abstract The Bistritz tabular form may be utilized in determining discrete-time system stability ... more Abstract The Bistritz tabular form may be utilized in determining discrete-time system stability with less computational effort as compared with the Jury tabular form. When appropriately constructed, the latter, however, provides the Schur-Cohn minors and the inner determinants related to the characteristic equation being tested. In this paper, we show that these quantities also may be extracted from the Bistritz tabular form. The cases of polynomials with both real- and complex-valued coefficients are studied. An important consequence of these relationships is the possibility of utilizing the Bistritz table in determining stability of two- and multi-dimensional discrete-time systems

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Delta-operator formulated discrete-time approximations of continuous-time systems

IEEE Transactions on Automatic Control, Mar 1, 1994

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Research paper thumbnail of Why do people believe COVID-19 conspiracy theories?

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Clustering Edges in Directed Graphs

arXiv (Cornell University), Feb 23, 2022

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Research paper thumbnail of Supplementary materials to: Do conspiracy beliefs form a belief system? Examining the structure and organization of conspiracy beliefs

Bookmarks Related papers MentionsView impact

Research paper thumbnail of <title>Single-input/multi-output strategies for floor vibration control</title>

Proceedings of SPIE, Apr 20, 2000

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Rule mining and missing-Value prediction in the presence of data ambiguities

The success of knowledge discovery in real-world domains often depends on our ability to handle d... more The success of knowledge discovery in real-world domains often depends on our ability to handle data imperfections. Here we study this problem in the framework of association mining, seeking to identify frequent itemsets in transactional databases where the presence of some items in a given transaction is unknown. We want to use the frequent itemsets to predict "missing items": based on the partial contents of a shopping cart, predict what else will be added. We describe a technique that addresses this task, and report experiments illustrating its behavior.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Linear time and space algorithm for computing all the fagin-halpern conditional beliefs generated from consonant belief functions

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Resource management of task oriented distributed sensor networks

In this paper we provide a foundation for a unified analysis of both the decision fusion and cong... more In this paper we provide a foundation for a unified analysis of both the decision fusion and congestion avoidance aspects of a task-oriented distributed sensor network (DSN). Such a framework allows network resource management to be carried out in a manner that is sensitive to the overall objectives of the DSN rather than decoupling them via perhaps simple fairness strategies.

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Research paper thumbnail of Uncertain Logic Processing: logic-based inference and reasoning using Dempster–Shafer models

International Journal of Approximate Reasoning, Apr 1, 2018

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Research paper thumbnail of Consensus in the Presence of Multiple Opinion Leaders: Effect of Bounded Confidence

IEEE Transactions on Signal and Information Processing over Networks, Sep 1, 2016

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A distributed congestion and power control algorithm to achieve bounded average queuing delay in wireless networks

Telecommunication Systems, Jan 13, 2010

Allocating limited resources such as bandwidth and power in a multi-hop wireless network can be f... more Allocating limited resources such as bandwidth and power in a multi-hop wireless network can be formulated as a Network Utility Maximization (NUM) problem. In this approach, both transmitting source nodes and relaying link nodes exchange information allowing for the NUM problem to be solved in an iterative distributed manner. Some previous NUM formulations of wireless network problems have considered the

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Dynamics of Consensus Formation among Agent Opinions

CRC Press eBooks, Dec 19, 2017

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Efficient sensor selection with application to time varying graphs

This paper addresses the problem of efficiently selecting sensors such that the mean squared esti... more This paper addresses the problem of efficiently selecting sensors such that the mean squared estimation error is minimized under jointly Gaussian assumptions. First, we propose an O(n3) algorithm that yields the same set of sensors as a previously published near mean squared error (MSE) optimal method that runs in O(n4). Then we show that this approach can be extended to efficient sensor selection in a time varying graph. We consider a rank one modification to the graph Laplacian, which captures the cases where a new edge is added or deleted, or an edge weight is changed, for a fixed set of vertices. We show that we can efficiently update the new set of sensors in O(n2) time for the best case by saving computations that were done for the original graph. Experiments demonstrate advantages in computational time and MSE accuracy in the proposed methods compared to recently developed graph sampling methods.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Who Supports QAnon? A Case Study in Political Extremism

The Journal of Politics, Jul 1, 2022

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A necessary and sufficient condition for robust asymptotic stability of time-variant discrete systems

IEEE Transactions on Automatic Control, 1993

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The psychological and political correlates of conspiracy theory beliefs

Scientific Reports, Dec 15, 2022

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Research paper thumbnail of Correlation Coefficient Based Template Matching: Accounting for Uncertainty in Selecting the Winner

The problem of selecting a template that matches a given candidate signal is applicable across a ... more The problem of selecting a template that matches a given candidate signal is applicable across a wide variety of domains. Using the correlation coefficient as the avenue for selecting the winning template is perhaps the most common technique. The challenge lies in selecting the winning template when there is no clear separation between the correlation coefficient values of the winning template and the others. In this paper, we present a simple Dempster-Shafer (DS) theoretic model that enables one to capture the uncertainty regarding the winner selection in correlation coefficient based template matching. The DS theoretic framework provides an avenue to develop the model with few resources and little to no prior knowledge. We validate the model using several numerical examples and a numerical character recognition application where the evidence provided by several sets of templates are combined using a DS theoretic fusion strategy to arrive at a better decision.

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