Control and diagnosis of real-time systems under finite-precision measurement of time

A discrete event system (DES) is an event-driven system that evolves according to abrupt occurrences of discrete changes (events). The domain of such systems encompasses aspects of many man-made systems such as manufacturing systems, telephone networks, communication protocols, traffic systems, embedded software, asynchronous hardware, robotics, etc. Supervisory control theory for DESs studies the existence and synthesis of the supervisory controllers, namely, supervisors that restrict the system behaviors by dynamically disabling certain controllable events so that the controlled close-loop system could behave as desired. Extensive work on supervisory control of untimed DESs exists and the extension to the timed setting has been reported in the literature. In this dissertation, we study the supervisory control of dense-time DESs in which the digital-clocks of finite-precision are employed to observe the event occurrence times, thereby relaxing the assumption of the prior works that time can be measured precisely. In our setting, the passing of time is measured using the number of ticks generated by a digital-clock and we allow the plant events and digital-clock ticks to occur concurrently. We formalize the notion of a control policy that issues the control actions based on the observations of events and their occurrence times as measured using a digital-clock, and show that such a control policy can be equivalently represented as a digitalized -automaton, namely, an untimed-automaton that evolves over the events (of the plant) and ticks (of the digital-clock). We introduce the notion of observability with respect to the partial observations of time resulting from the use of a digital-clock, and show that this property together with controllability serves as a necessary and sufficient condition for the existence of a supervisor to enforce a real-time specification on a dense-time discrete event plant. The observability condition presented in the dissertation is very different from the one arising due to a partial observation of events since a partial observation of time is in general nondeterministic (the number of ticks generated in any time interval can vary from execution to execution of a digital-clock). We also present a method to verify the proposed observability and controllability conditions, and an algorithm to compute a supervisor when such conditions are satisfied. Furthermore we examine the lattice structure of a class of timing-mask observable languages, and show that the proposed observability is not preserved under intersection but preserved under union. Fault diagnosis for DESs is to detect the occurrence of a fault so as to enable any corrective actions. It is crucial in automatic control of large complex man-made systems and has attracted considerable attention in the literature of reliability engineering, control and computer science. For the event-driven systems with timing-requirements such as manufacturing systems, communication networks, real-time scheduling and traffic systems, fault diagnosis involves detecting the timing-faults, besides the sequence-faults. This requires monitoring timing and sequence of events, both of which may only be partially observed in practice. In this dissertation, we extend the prior works on fault diagnosis of timed DESs by allowing time to be partially observed using a digital-clock which measures the advancement of time with finite precision by the number of ticks. For the diagnosis purposes, the set of nonfaulty timed-traces is specified as another timed-automaton that is deterministic. We show that the set of timed-traces observed using a digital-clock with finite precision is regular, i.e., can be represented using a finite (untimed) automaton. We also show that the verification of diagnosability (the ability to detect the execution of a faulty timed-trace within a bounded time delay) as well as the off-line synthesis of a diagnoser are decidable by reducing these problems to the untimed setting. The reduction to the untimed setting also suggests an effective method for the off-line computation of a diagnoser as well as its on-line implementation for diagnosis. The aforementioned results are further extended to the nondeterministic setting, i.e., diagnosis of dense-time DESs using digital-clocks under nondeterministic event observation mask. We introduce the notion of lifting (associating each event with each of its nondeterministic observations), and show that diagnosis of dense-time DESs employing digital-clocks to observe event occurrence times under nondeterministic event observation mask can be reduced to that of the deterministic setting, i.e., diagnosis of the lifted dense-time DESs under the deterministic lifted event observation mask, and hence can be further reduced to diagnosis of the untimed setting

Proceedings, MSVSCC 2016

Proceedings of the 10th Annual Modeling, Simulation & Visualization Student Capstone Conference held on April 14, 2016 at VMASC in Suffolk, Virginia

The dissolution of Yugoslavia and the Badinter Arbitration Commission.

This thesis examines the dissolution of Yugoslavia during 1991-2 and the involvement of a legal commission, known as the Badinter Arbitration Commission, in this process. This Commission was an ad hoc legal organ which was created for the purpose of assisting in the peaceful resolution of the conflict which erupted in Yugoslavia during the latter years of the Cold War and continued throughout the post-Cold war period. Whether it can truly be described as having been fully resolved remains to be seen. The thesis describes international events leading to the end of the Cold War, domestic events leading to Yugoslavia's dissolution and institutional responses leading to the creation of the Commission. The Commission's jurisprudence is analysed, with particular focus on the Commission's advice relating to issues surrounding the dissolution process. Having been mandated to operate in a civil conflict at a time of great turbulence in contemporary international relations, one cannot ignore certain issues of wider interest. Fundamentally, one must question whether Yugoslavia represents an international legal anomaly or evidences changes in international law and threats to international peace and security. One must seek to draw lessons from the way in which the Yugoslav conflict arose and the way in which a peaceful-settlement was sought if international law's current responses are to be assessed

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen

Texas Law Review

Journal containing articles, notes, book reviews, and other analyses of law and legal cases

Dictionary of privacy, data protection and information security

The Dictionary of Privacy, Data Protection and Information Security explains the complex technical terms, legal concepts, privacy management techniques, conceptual matters and vocabulary that inform public debate about privacy. The revolutionary and pervasive influence of digital technology affects numerous disciplines and sectors of society, and concerns about its potential threats to privacy are growing. With over a thousand terms meticulously set out, described and cross-referenced, this Dictionary enables productive discussion by covering the full range of fields accessibly and comprehensively. In the ever-evolving debate surrounding privacy, this Dictionary takes a longer view, transcending the details of today''s problems, technology, and the law to examine the wider principles that underlie privacy discourse. Interdisciplinary in scope, this Dictionary is invaluable to students, scholars and researchers in law, technology and computing, cybersecurity, sociology, public policy and administration, and regulation. It is also a vital reference for diverse practitioners including data scientists, lawyers, policymakers and regulators

Confronting (In)Security: Forging Legitimate Approaches to Security and Exclusion in Migration Law

Perceived connections between security concerns and migration are a central preoccupation of our time. This dissertation explores how the preoccupation has played out in the Canadian context and asserts that a basic and common infirmity of administrative decision-making in this domain is a lack of justification. The dissertation commences by exploring foundational debates within immigration theory about borders, exclusion, the rule of law and the role of justification in decision-making in liberal democracies, particularly in times of perceived emergency. From there, the dissertation moves on to an exploration of immigration inadmissibility determinations in Canada, with particular attention to the emergence of security concerns as a primary ground of inadmissibility. Central to this exploration is a quantitative analysis of inadmissibility determinations rendered by the Immigration and Refugee Board of Canada, pursuant to s34 of the Immigration and Refugee Protection Act [IRPA]. The results of the quantitative analysis challenge the perception that migrants within Canada pose an exceptional security threat to the state, as the provisions related directly to Canadian national security and public safety have essentially never been invoked in s34 cases. Rather, the majority of those found inadmissible to Canada on security grounds tend to be asylum-seekers or Convention refugees from countries of the Global South that have undergone periods of domestic political turmoil. This fact raises important questions about the obligations of the Canadian state with respect to the principle of non-refoulement, obligations that can only be met, it is argued, through appropriately deliberative processes. To help explain the results of the quantitative data and to identify ways of enhancing security-related decision making, the dissertation proceeds to a body of scholarship on international law that places the concerns of individuals from the Global South at the centre of its analysis. This approach referred to as the Third World Approaches to International Law movement (TWAIL) emphasizes the importance of history, context and individual experience when confronting legal domains, such as the security-inadmissibility context, that affect people from the Global South. The dissertation then concludes by pairing the TWAIL analysis with an approach to administrative law that posits that legitimacy and justification in administrative decisions are contingent upon good faith exercises of dialogue between decision-makers and those who are affected by their decisions. In combining this approach to administrative law with TWAIL, the dissertation closes by putting forward a number of proposals for reform that would enhance the quality, justification and legitimacy of decisions in the security-inadmissibility context

Confronting (In) Security: Forging Legitimate Approaches to Security and Exclusion in Migration Law

Perceived connections between security concerns and migration are a central preoccupation of our time. This dissertation explores how the preoccupation has played out in the Canadian context and asserts that a basic and common infirmity of administrative decision-making in this domain is a lack of justification. The dissertation commences by exploring foundational debates within immigration theory about borders, exclusion, the rule of law and the role of justification in decision-making in liberal democracies, particularly in times of perceived emergency. From there, the dissertation moves on to an exploration of immigration inadmissibility determinations in Canada, with particular attention to the emergence of security concerns as a primary ground of inadmissibility. Central to this exploration is a quantitative analysis of inadmissibility determinations rendered by the Immigration and Refugee Board of Canada, pursuant to s34 of the Immigration and Refugee Protection Act [IRPA]. The results of the quantitative analysis challenge the perception that migrants within Canada pose an exceptional security threat to the state, as the provisions related directly to Canadian national security and public safety have essentially never been invoked in s34 cases. Rather, the majority of those found inadmissible to Canada on security grounds tend to be asylum-seekers or Convention refugees from countries of the Global South that have undergone periods of domestic political turmoil. This fact raises important questions about the obligations of the Canadian state with respect to the principle of non-refoulement, obligations that can only be met, it is argued, through appropriately deliberative processes. To help explain the results of the quantitative data and to identify ways of enhancing security-related decision making, the dissertation proceeds to a body of scholarship on international law that places the concerns of individuals from the Global South at the centre of its analysis. This approach referred to as the Third World Approaches to International Law movement (TWAIL) emphasizes the importance of history, context and individual experience when confronting legal domains, such as the security-inadmissibility context, that affect people from the Global South. The dissertation then concludes by pairing the TWAIL analysis with an approach to administrative law that posits that legitimacy and justification in administrative decisions are contingent upon good faith exercises of dialogue between decision-makers and those who are affected by their decisions. In combining this approach to administrative law with TWAIL, the dissertation closes by putting forward a number of proposals for reform that would enhance the quality, justification and legitimacy of decisions in the security-inadmissibility context

Artificial Frontiers, Simulated Indigeneity: Western Big-Budget Open World Games and the Settler Colonial Imaginary

This dissertation studies Western big-budget video games of a genre often referred to as “open world.” By tracking the concept of the “frontier” as a settler colonial (and later neoliberal) signal for space that invites access, I argue these games are both expressive of and cater to settler and neoliberal cultural anxieties regarding extermination and desires for accumulative dominance. Furthermore, these games exhibit their settler colonial and neoliberal ideologies through their narratives, gameplay mechanics, and productive contexts. That exhibition of ideology comes in several formulas of settler and neoliberal cultural production identified by various fields of scholarship. This dissertation, drawing from Indigenous studies, video game studies, post-colonial and Marxist theory, studies the Grand Theft Auto and Red Dead Redemption series, Assassin’s Creed 3 and the so-called “Ubisoft formula” generally, as well as Horizon Zero Dawn to argue a few central points about big-budget Western open world games: (1) they are what I call artificial frontiers, and as such are the preeminent entertainment of settler colonial cultural mores and the sustained eliminative and accumulative logics of those mores’ historical frontierism; (2) they reveal, reflect, propagate, accommodate, and assuage settler colonial anxieties and desires; (3) they exhibit (though attempt to obscure) the genocidal logic and exploitative relations of Western settler colonialism and neoliberalism; consequently, to some extent this dissertation argues the video game industry’s social function shows the compatibility of settler-influenced neoliberalism with fascist ideology

Not All’s Fair in Love and War: Dynasticism and Composite State Longevity in Early Modern Europe

Some composite states, notably Poland-Lithuania and the Holy Roman Empire, outlived the Peace of Westphalia by over one hundred years. This is puzzling for the study of international politics because good theoretical reasons expect the multiple countervailing pressures acting on these states to have brought about a rapid decline and dissolution. In this dissertation, I propose a theoretical approach that satisfactorily accounts for why some composite states survived until the dawn of the Napoleonic Wars. The theory of dynasticism and dynastic deterrence argues that dynastic intermarriage and proximate kinship ties between dynastic rulers created deterrent effects that led to stability on the level of sovereign control. The most direct consequence of this theory is that hereditary monarchs with dynastic aims will tend to avoid waging wars of absolute conquest against each other, though wars of limited gains are not precluded. Given the inability of competing explanations—a reconstructed early modern realism and intergenerational leadership learning—to account for both the manner of survival and demise of composite states that lived till old age, it can be strongly inferred that dynastic deterrent effects ensured longevity by protecting such polities from facing conquest-attempts from other monarchs, the most serious existential threat these composite states could have faced. The reason that dynastic deterrence holds is because dynastic wives and families of origin play the role of hostages. The parental house of the dynastic wife will tend to avoid wars of conquest against the kingdoms wherein reside their daughters, and similarly dynastic husbands will avoid conquering the birth-dynasty of their wives. In addition, wars of conquest damage the reputation of the dynastic house of a monarch, and this in turn harms the marriage chances of dynastic heirs. Wars of conquest, then, act at cross-purposes with the ubiquitous motive of dynastic aggrandizement, which aims to uplift the power and prestige of the dynastic house, and were largely disdained (with some exceptions) by the rulers of ancien régime Europe. It should be noted that this dynamic did not hold in the colonies, but I do not attempt in this dissertation to answer the question of why. In the empirical case analyses, I use this theoretical framework to explain the early dissolution of two composite states (England-Scotland and the Iberian Union) when juxtaposed with other composite states that survived for longer in their same regions, and the longevity and eventual demise of two further composite states (Poland-Lithuania and the Holy Roman Empire) after weathering some near-death crises. Oft mentioned but rarely studied directly, dynasticism and dynastic intermarriage have been largely ignored by the field of International Relations. This is unfortunate, as the ties of marriage and kinship between early modern dynastic rulers represent a fertile source of theoretical insights and empirical material for testing contemporary theories and deriving puzzles. I hope this study will stimulate further research into this fascinating area