Дисертації: "Session and event systems"

1

Редько, Владислав Ігорович. "Система збору аналітики додатку для розробників ігор". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/43959.

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Аналітика – інструмент для розроблення та правильного підтримання програмних продуктів. Системи аналітики є актуальними для усіх пост-релізних етапах розробки гри – від збору аналітики для визначення залученості гравців на початкових етапах, до збору аналітики для розробки оновлень. Мета роботи – проаналізувати існуючі системи аналітки, та на основі дослідження розробити систему аналітики, яка б легко інтегрувалась в будь-яку гру, розроблену за допомогою C#, та відображала дані в зручному для розробника вигляді. Записка містить 64 сторінки, 29 рисунків, 4 додатки та 14 посилань.
Analytics is a tool for developing and properly maintaining software products. Analytics systems are relevant for all post – release stages of game development-from collecting analytics to determining player engagement in the initial stages, to collecting analytics to develop updates. The aim of the work is to analyze existing analytics systems, and based on the research, develop an analytics system that would easily integrate into any game developed using C#, and display data in a convenient form for the developer. The note contains 64 pages, 29 Figures, 4 attachments and 14 links.
Аналитика - инструмент для разработки и правильного поддержания программных продуктов. Системы аналитики актуальны для всех пост-релизных этапах разработки игры - от сбора аналитики для определения вовлеченности игроков на начальных этапах, к сбору аналитики для разработки обновлений. Цель работы - проанализировать существующие системы Аналитки, и на основе исследования разработать систему аналитики, которая легко интегрировалась в любую игру, разработанную с помощью C #, и отражала данные в удобном для разработчика виде. Записка содержит 64 страницы, 29 рисунков, 4 приложения и 14 ссылок.

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2

Wulff, Tobias. "Evaluation of and Mitigation against Malicious Traffic in SIP-based VoIP Applications in a Broadband Internet Environment." Thesis, University of Canterbury. Computer Science and Software Engineering, 2010. http://hdl.handle.net/10092/5120.

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Voice Over IP (VoIP) telephony is becoming widespread, and is often integrated into computer networks. Because of his, it is likely that malicious software will threaten VoIP systems the same way traditional computer systems have been attacked by viruses, worms, and other automated agents. While most users have become familiar with email spam and viruses in email attachments, spam and malicious traffic over telephony currently is a relatively unknown threat. VoIP networks are a challenge to secure against such malware as much of the network intelligence is focused on the edge devices and access environment. A novel security architecture is being developed which improves the security of a large VoIP network with many inexperienced users, such as non-IT office workers or telecommunication service customers. The new architecture establishes interaction between the VoIP backend and the end users, thus providing information about ongoing and unknown attacks to all users. An evaluation of the effectiveness and performance of different implementations of this architecture is done using virtual machines and network simulation software to emulate vulnerable clients and servers through providing apparent attack vectors.

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3

Coen, Stephanie. "NEXUS Poster Session & Book Launch 2009 - Event Flyer." NEXUS, 2009. http://hdl.handle.net/2429/15386.

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4

Aiken, Milam Worth. "An expert systems approach to group decision support systems pre-session planning." Diss., The University of Arizona, 1991. http://catalog.hathitrust.org/api/volumes/oclc/31253019.html.

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5

Schulz, Joseph Edward. "A desision support system for session scheduling." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/25106.

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6

Neykova, Rumyana. "Multiparty session types for dynamic verification of distributed systems." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/45276.

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In large-scale distributed systems, each application is realised through interactions among distributed components. To guarantee safe communication (no deadlocks and communication mismatches) we need programming languages and tools that structure, manage, and policy-check these interactions. Multiparty session types (MPST), a typing discipline for structured interactions between communicating processes, offers a promising approach. To date, however, session types applications have been limited to static verification, which is not always feasible and is often restrictive in terms of programming API and specifying policies. This thesis investigates the design and implementation of a runtime verification framework, ensuring conformance between programs and specifications. Specifications are written in Scribble, a protocol description language formally founded on MPST. The central idea of the approach is a dynamic monitor, which takes a form of a communicating finite state machine, automatically generated from Scribble specifications, and a communication runtime stipulating a message format. We extend and apply Scribble-based runtime verification in manifold ways. First, we implement a Python library, facilitated with session primitives and verification runtime. We integrate the library in a large cyber-infrastructure project for oceanography. Second, we examine multiple communication patterns, which reveal and motivate two novel extensions, asynchronous interrupts for verification of exception handling behaviours, and time constraints for enforcement of realtime protocols. Third, we apply the verification framework to actor programming by augmenting an actor library in Python with protocol annotations. For both implementations, measurements show Scribble-based dynamic checking delivers minimal overhead and allows expressive specifications. Finally, we explore a static analysis of Scribble specifications as to efficiently compute a safe global state from which a monitored system of interacting processes can be recovered after a failure. We provide an implementation of a verification framework for recovery in Erlang. Benchmarks show our recovery strategy outperforms a built-in static recovery strategy, in Erlang, on a number of use cases.

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7

Fiege, Ludger. "Visibility in event based systems." Phd thesis, [S.l. : s.n.], 2005. http://elib.tu-darmstadt.de/diss/000574.

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8

Van, der Westhuizen Eugene Daniel. "A session layer for the X.400 message handling system." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/18228.

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Bibliography: pages 233-235.
The CCITT X.400 Message Handling System resides in the Application Layer of the seven-layer Reference Model for Open Systems Interconnection. It bypasses the services of the Presentation Layer completely to interact directly with the Session Layer. The objectives of this thesis are to show how the general Session Layer may be tailored to be minimally conformant to the requirements of X. 400; to produce a formal specification of this session layer; and to show how this session layer may be implemented on a real system. The session services required by X. 400 are those of the Halfduplex, Minor Synchronization, Exceptions and Activity Management functional units of the CCITT X.215 Session Service Definition. These services, and particularly their use by X.400, are described in detail. State tables describing these services are derived from the general session service state tables. Those elements of the CCITT X. 225 Session Protocol Specification which are required to provide only those services required by X. 400 are described in detail. State tables describing this session protocol are derived from the general session protocol state tables. A formal specification of the session layer for X.400 is presented using the Formal Description Technique Estelle. This specification includes a complete session entity, which characterizes the entire session layer for X.400. A session entity for supporting X.400 is partially implemented and interfaced to an existing X.400 product on a real system. Only the Session Connection Establishment Phase of the session protocol is implemented to illustrate the technique whereby the entire session protocol may be implemented. This implementation uses the C programming language in the UNIX operating system environment.

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9

Chen, Tsu-Chun. "Theories for Session-based Governance for Large-scale Distributed Systems." Thesis, Queen Mary, University of London, 2013. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8778.

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Large-scale distributed systems and distributed computing are the pillars of IT infrastructure and society nowadays. Robust theoretical principles for designing, building, managing and understanding the interactive behaviours of such systems need to be explored. A promising approach for establishing such principles is to view the session as the key unit for design, execution and verification. Governance is a general term for verifying whether activities meet the specified requirements and for enforcing safe behaviours among processes. This thesis, based on the asynchronous -calculus and the theory of session types, provides a monitoring framework and a theory for validating specifications, verifying mutual behaviours during runtime, and taking actions when noncompliant behaviours are detected. We explore properties and principles for governing large-scale distributed systems, in which autonomous and heterogeneous system components interact with each other in the network to accomplish application goals. This thesis, incorporating lessons from my participation in a substantial practical project, the Ocean Observatories Initiative (OOI), proposes an asynchronous monitoring framework and the process calculus for dynamically governing the asynchronous interactions among distributed multiple applications. We prove that this monitoring model guarantees the satisfaction of global assertions, and state and prove theorems of local and global safety, transparency, and session fidelity. We also study and introduce the semantic mechanisms for runtime session-based governance and the principles of validation of stateful specifications through capturing the runtime asynchronous interactions.

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10

Seyboth, Georg Sebastian. "Event-based Controlfor Multi-Agent Systems." Thesis, KTH, Reglerteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105117.

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In this thesis, a novel approach to the average consensus problem for multi-agent systems is followed. A new event-based control strategy is proposed, which incorporates event-based scheduling of state measurement broadcasts over the network. The control-laws are based on the resulting piecewise constant functions of these measurement values. This facilitates implementation on digital platforms such as microprocessors and reduces the number of interagent communications over the network. Starting from a basic problem setup with singleintegrator agents, fixed undirected connected communication topologies, and no time-delays, the novel strategy is developed. Different triggering conditions guaranteeing convergence to an adjustable region around the average consensus point or asymptotic convergence to this point, respectively, are discussed. Numerical simulations show the effectiveness of this approach, outperforming classical time-scheduled implementations of the consensus protocol in terms of load on the communication medium. Furthermore the problem class is extended to networks with directed communication links, switching topologies, and time-delays in the communication as well as to agents with double-integrator dynamics. As an illustrative example, the novel strategy is applied to a formation control problem of non-holonomic mobile robots in the plane.

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11

Zhang, Xueqin. "Control of Boolean discrete event systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28860.pdf.

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12

Carlson, Jan. "Event Pattern Detection for Embedded Systems." Doctoral thesis, Västerås : Department of Computer Science and Electronics, Mälardalen University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-231.

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13

Desai, Sasi Bharath. "Discrete Event Simulation of Elevator Systems." Scholarship @ Claremont, 2012. http://scholarship.claremont.edu/cmc_theses/343.

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The intent of this paper is to present the reader with a simple comparison of two systems of vertical transportation. Vertical transportation is a a relatively new field and is the subject of much interest in today's world. As buildings get taller and real estate becomes more expensive, the need to find a quick, efficient system with a small footprint becomes important. By performing a simulation and subjecting the two systems under study to similar traffic conditions, one can determine the effectiveness of one system relative to the other. Additionally, we look at the effects of changing various system attributes to gain a better understanding of the primary drivers of average travel time.

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14

Stoddart, Bill. "The event based modelling of systems." Thesis, Teesside University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411174.

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15

Huang, Jing. "Directed control of discrete event systems." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3369844.

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16

Guo, Ce. "Reconfigurable predictive systems for event streams." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/50159.

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The study of event streams involves modelling arrival times of discrete random events. Predictive systems for event streams infer information about future occurrences of random events. These systems are useful for various applications such as stock trading modelling and earthquake analysis, but the computational burdens limit their predictive power. This thesis addresses the design and optimisation of reconfigurable predictive systems for event streams. The first contribution of this thesis is the reconfigurable acceleration solution for the calculations in the Hawkes point process models. We propose reconfigurable dataflow engines for intensity evaluation and likelihood evaluation for univariate and multivariate Hawkes point process models. We also establish an efficient collaboration scheme between the CPU platform and the reconfigurable accelerator to speed up parameter estimation. The second contribution of this thesis is a novel predictive model for event streams. As the Hawkes point process models have limited predictive accuracy and low computational efficiency, we propose a predictive model for event streams using regression techniques. We derive the model from the intensity function of the Hawkes point process, but the final form of the proposed model works without point process models. A software system based on the proposed model reduces the prediction error by 3\%--7\% compared to a system based on the Hawkes process. A hardware-accelerated system based on the proposed model is 5--66 times faster in model fitting compared to the accelerated system based on the Hawkes process, while the two systems produce similar predictive accuracy. The third contribution of this thesis is the design of two reconfigurable accelerators for time series analysis. One accelerator is for the estimation of correlation for multivariate time series. The other accelerator is for the ordinal pattern encoding for univariate time series. We design the two accelerators by transforming the calculations of the corresponding statistical metrics into pipeline-friendly forms. Compared to multicore CPUs, both accelerators show high efficiency for large time series data.

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17

Li, Chunhui. "Performance management of event processing systems." Thesis, Aston University, 2014. http://publications.aston.ac.uk/25175/.

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This thesis is a study of performance management of Complex Event Processing (CEP) systems. Since CEP systems have distinct characteristics from other well-studied computer systems such as batch and online transaction processing systems and database-centric applications, these characteristics introduce new challenges and opportunities to the performance management for CEP systems. Methodologies used in benchmarking CEP systems in many performance studies focus on scaling the load injection, but not considering the impact of the functional capabilities of CEP systems. This thesis proposes the approach of evaluating the performance of CEP engines’ functional behaviours on events and develops a benchmark platform for CEP systems: CEPBen. The CEPBen benchmark platform is developed to explore the fundamental functional performance of event processing systems: filtering, transformation and event pattern detection. It is also designed to provide a flexible environment for exploring new metrics and influential factors for CEP systems and evaluating the performance of CEP systems. Studies on factors and new metrics are carried out using the CEPBen benchmark platform on Esper. Different measurement points of response time in performance management of CEP systems are discussed and response time of targeted event is proposed to be used as a metric for quality of service evaluation combining with the traditional response time in CEP systems. Maximum query load as a capacity indicator regarding to the complexity of queries and number of live objects in memory as a performance indicator regarding to the memory management are proposed in performance management of CEP systems. Query depth is studied as a performance factor that influences CEP system performance.

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18

Ponce, de León Hernan. "Testing concurrent systems through event structures." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0035/document.

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Les systèmes logiciels complexes sont omniprésents dans notre vie quotidienne. De ce fait, un dysfonctionnement peut occasionner aussi bien une simple gêne qu'un danger mettant en péril des vies humaines. Le test est l'une des techniques les plus répandues (en particulier dans l'industrie) pour détecter les erreurs d'un système. Lorsque le cahier des charges d'un système est décrit par une spécification formelle, le test de conformité est utilisé pour garantir un certain niveau de confiance dans la correction d'une implémentation de ce système - dans ce cadre, la relation de conformité formalise la notion de correction. Cette thèse se focalise sur le test de conformité pour les systèmes concurrents. Le test de conformité pour les systèmes concurrents utilise principalement des modèles qui interprètent la concurrence par des entrelacements. Néanmoins, cette approche souffre du problème de l'explosion de l'espace d'états et elle n'offre pas la possibilité de tester certaines propriétés de la spécification telle que l'indépendance entre actions. Pour ces raisons, nous utilisons une sémantique d'ordres partiels pour la concurrence. De plus, nous proposons une nouvelle sémantique qui permet à certaines actions concurrentes d'être entrelacées et en force d'autres à être implémentées indépendamment. Nous proposons une généralisation de la relation de conformité ioco où les spécifications sont des réseaux de Petri et leur sémantique d'ordres partiels est donnée par leur dépliage. Cette relation de conformité permet de préserver l'indépendance, dans l'implémentation, des actions spécifiées comme concurrentes. Nous présentons un cadre de test complet pour cette relation. Nous définissons la notion de cas de test globaux gérant la concurrence, réduisant ainsi non seulement la taille des cas de test mais aussi celle de la suite de tests. Nous montrons comment les cas de test globaux peuvent être construits à partir du dépliage de la spécification en s'appuyant sur une traduction SAT, et nous réduisons le problème de la sélection de tests à la sélection d'un préfixe fini de ce dépliage : nous définissons différents critères de sélection à partir de la notion d'événement limite (cut-off event). Enfin, en supposant que chaque processus d'un système distribué possède une horloge locale, nous montrons que la conformité globale peut être testée dans une architecture de test distribuée en utilisant seulement des testeurs locaux ne communiquant pas entre eux
Complex systems are everywhere and are part of our daily life. As a consequence, their failures can range from being inconvenient to being life-threatening. Testing is one of the most widely accepted techniques (especially in industry) to detect errors in a system. When the requirements of the system are described by a formal specification, conformance testing is used to guarantee a certain degree of confidence in the correctness of an implementation- in this setting a conformance relation formalizes the notion of correctness. This thesis focuses on conformance testing for concurrent systems. Conformance testing for concurrent system has mainly focused on models that interpret concurrency by interleavings. This approach does not only suf- fer from the state space explosion problem, but also lacks the ability to test properties of the specification such as independence between actions. For such reasons, we focus not only on partial order semantics for concurrency, but also propose a new semantics that allows to interleave some actions while forcing others to be implemented as independent. We propose a generalization of the ioco conformance relation, based on Petri nets specifications and their partial order semantics given by their unfoldings, preserving thus independence of actions from the specification. A complete testing framework for this conformance relation is presented. We introduce the notion of global test cases which handle concurrency, reducing not only the size of the test case, but also the number of tests in the test suite. We show how global test cases can be constructed from the unfolding of the specification based on a SAT encoding and we reduce the test selection problem to select a finite prefix of such unfolding: different testing criteria are defined based on the notion of cut-off events. Finally, we show that assuming each process of a distributed system has a local clock, global conformance can be tested in a distributed testing architecture using only local testers without any communication

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19

Su, Rong. "Decentralized fault diagnosis for discrete-event systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0024/MQ50393.pdf.

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20

Wang, Yuwei. "Supervisory control of Boolean discrete-event systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/MQ53446.pdf.

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21

Hu, Tun. "Communication states in decentralized discrete-event systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2002. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ65626.pdf.

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22

Bherer, Hans. "Controller Synthesis for Parameterized Discrete Event Systems." Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26696/26696.pdf.

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Les systèmes à événements discrets sont des systèmes dynamiques particuliers. Ils changent d’état de fa¸con discrète et le terme événement est utilisé afin de représenter l’occurrence de changements discontinus. Ces systèmes sont principalement construits par l’homme et on les retrouve surtout dans les secteurs manufacturier, de la circu- lation automobile, des bases de données et des protocoles de communication. Cette thèse s’intéresse au contrôle des systèmes paramétrés à événements discrets où les spécifications sont exprimées à l’aide de prédicats et satisfont une condition de similarité. Des conditions sont données afin de déduire des propriétés, en observation partielle ou totale, pour un système composé de n processus similaires à partir d’un système com- posé de n0 processus, avec n ≥ n0. De plus, il est montré comment inférer des politiques de contrôle en présence de relations d’interconnexion entre les processus. Cette étude est principalement motivée par la faiblesse des méthodes actuelles de synthèse pour le traitement des problèmes industriels de taille réelle.
Discrete event systems are a special type of dynamic systems. The state of these systems changes only at discrete instants of time and the term event is used to represent the occurrence of discontinuous changes. These systems are mostly man-made and arise in the domains of manufacturing systems, traffic systems, database management systems and communication protocols. This thesis investigates the control of parameterized discrete event systems when specifications are given in terms of predicates and satisfy a similarity assumption. For systems consisting of similar processes under total or partial observation, conditions are given to deduce properties of a system of n processes from properties of a system of n0 processes, with n ≥ n0. Furthermore, it is shown how to infer a control policy for the former from the latter’s, while taking into account interconnections between processes. This study is motivated by a weakness in current synthesis methods that do not scale well to huge systems.

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23

Birkholz, Simon. "Determinism and predictability in extreme event systems." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17495.

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In den vergangenen Jahrzehnten wurden extreme Ereignisse, die nicht durch Gauß-Verteilungen beschrieben werden können, in einer Vielzahl an physikalischen Systemen beobachtet. Während statistische Methoden eine zuverlässige Identifikation von extremen Ereignissen ermöglichen, ist deren Entstehungsmechanismus nicht vollständig geklärt. Das Auftreten von extremen Ereignissen ist nicht vollkommen verstanden, da sie nur selten beobachtet werden können und häufig unter schwer reproduzierbaren Bedingungen auftreten. Deshalb ist es erstrebenswert Experimente zu entwickeln, die eine einfache Beobachtung von extremen Ereignissen erlauben. In dieser Dissertation werden extreme Ereignisse untersucht, die bei Multi-Filamentation von Femtosekundenlaserimpulsen entstehen. In den Experimenten, die in dieser Dissertation vorgestellt werden, werden Multi-Filamente durch Hochgeschwindigkeitskameras analysiert. Die Untersuchung der raum-zeitlichen Dynamik der Multi-Filamente zeigt eine L-förmige Wahrscheinlichkeitsverteilung, Diese Beobachtung impliziert das Auftreten von extremen Ereignissen. Lineare Analyse liefert Hinweise auf die physikalischen Prozesse, die zur Entstehung der extremen Ereignisse führen und nicht-lineare Zeitreihen-Analyse charakterisiert die Dynamik des Systems. Die Analyse der Multi-Filamente wird außerdem auf extreme Ereignisse in Wellen-Messungen und optische Superkontinua angewandt. Die durchgeführten Analysen zeigen Unterschiede in den physikalischen Prozessen, die zur Entstehung von extremen Ereignissen führen. Extreme Ereignisse in optischen Fasern werden durch stochastische Fluktuationen von verstärktem Quantenrauschen dominiert. In Multi-Filamenten und Ozeanwellen resultieren extreme Ereignisse dagegen aus klassischer mechanischer Turbulenz, was deren Vorhersagbarkeit impliziert. In dieser Arbeit wird anhand der von Multi-Filament-Zeitreihen die Vorhersagbarkeit in einem kurzen Zeitfenster vor Auftreten des extremen Ereignisses bewiesen.
In the last decades, extreme events, i.e., high-magnitude phenomena that cannot be described within the realm of Gaussian probability distributions have been observed in a multitude of physical systems. While statistical methods allow for a reliable identification of extreme event systems, the underlying mechanism behind extreme events is not understood. Extreme events are not well understood due to their rare occurrence and their onset under conditions that are difficult to reproduce. Thus, it is desirable to identify extreme event scenarios that can serve as a test bed. Optical systems exhibiting extreme events have been discovered to be ideal for such tests, and it is now desired to find more different examples to improve the understanding of extreme events. In this thesis, multifilamentation formed by femtosecond laser pulses is analyzed. Observation of the spatio-temporal dynamics of multifilamentation shows a heavy-tailed fluence probability distribution. This finding implies the onset of extreme events during multifilamentation. Linear analysis gives hints on the processes that drive the formation of extreme events. The multifilaments are also analyzed by nonlinear time series analysis, which provides information on determinism and chaos in the system. The analysis of the multifilament s is compared to an analysis of extreme event time series from ocean wave measurements and the supercontinuum output of an optical fiber. The analysis performed in this work shows fundamental differences in the extreme event mechnaism. While the extreme events in the optical fiber system are ruled by the stochastic changes of amplified quantum noise, in the multifilament and the ocean system extreme events appear as a result of the classical mechanical process of turbulence. This implies the predictability of extreme events. In this work, the predictability of extreme events is proven to be possible in a brief time window before the onset of the extreme event.

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24

Zeldovich, Nickolai 1981. "Concurrency control for multiprocessor event-driven systems." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87303.

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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (p. 41-43).
by Nickolai Zeldovich.
M.Eng.

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25

Muthiah, Sathappan. "Design and Maintenance of Event Forecasting Systems." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/102866.

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With significant growth in modern forms of communication such as social media and micro- blogs we are able to gain a real-time understanding into events happening in many parts of the world. In addition, these modern forms of communication have helped shed light into the increasing instabilities across the world via the design of anticipatory intelligence systems [45, 43, 20] that can forecast population level events like civil unrest, disease occurrences with reasonable accuracy. Event forecasting systems are generally prone to become outdated (model drift) as they fail to keep-up with constantly changing patterns and thus require regular re-training in order to sustain their accuracy and reliability. In this dissertation we try to address some of the issues associated with design and maintenance of event forecasting systems in general. We propose and showcase performance results for a drift adaptation technique in event forecasting systems and also build a hybrid system for event coding which is cognizant of and seeks human intervention in uncertain prediction contexts to maintain a good balance between prediction-fidelity and cost of human effort. Specifically we identify several micro-tasks for event coding and build separate pipelines for each with uncertainty estimation capabilities and thereby be able to seek human feedback whenever required for each micro-task independent of the rest.
Doctor of Philosophy
Event forecasting systems help reduce violence, loss/damage to humans and property. They find applicability in supply chain management, prioritizing citizen grievances, designing mea- sures to control violence and minimize disruptions and also in applications like health/tourism by providing timely travel alerts. Several issues exist with the design and maintenance of such event forecasting systems in general. Predictions from such systems may drift away from ground reality over time if not adapted to various shifts (or changes) in event occurrence patterns in real-time. A continuous source of ground-truth events is of paramount necessity for the continuous maintenance of forecasting systems. However ground-truth events used for training may not be reliable but often information about their uncertainty is not reflected in the systems that are used to build the ground truth. This dissertation focuses on addressing such issues pertaining to design and maintenance of event forecasting systems. We propose a framework for online drift-adaptation and also build machine learning methods capable of modeling and capturing uncertainty in event detection systems. Finally we propose and built a hybrid event coding system that can capture the best of both automated and manual event coders. We breakdown the overall event coding pipeline into several micro-tasks and propose individual methods for each micro-task. Each method is built with the capability to know what it doesn't know and thus is capable of balancing quality vs throughput based on available human resources.

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26

Thiele, Johannes C. "Deep learning in event-based neuromorphic systems." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS403/document.

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Inférence et apprentissage dans les réseaux de neurones profonds nécessitent une grande quantité de calculs qui, dans beaucoup de cas, limite leur intégration dans les environnements limités en ressources. Les réseaux de neurones évènementiels de type « spike » présentent une alternative aux réseaux de neurones artificiels classiques, et promettent une meilleure efficacité énergétique. Cependant, entraîner les réseaux spike demeure un défi important, particulièrement dans le cas où l’apprentissage doit être exécuté sur du matériel de calcul bio-inspiré, dit matériel neuromorphique. Cette thèse constitue une étude sur les algorithmes d’apprentissage et le codage de l’information dans les réseaux de neurones spike.A partir d’une règle d’apprentissage bio-inspirée, nous analysons quelles propriétés sont nécessaires dans les réseaux spike pour rendre possible un apprentissage embarqué dans un scénario d’apprentissage continu. Nous montrons qu’une règle basée sur le temps de déclenchement des neurones (type « spike-timing dependent plasticity ») est capable d’extraire des caractéristiques pertinentes pour permettre une classification d’objets simples comme ceux des bases de données MNIST et N-MNIST.Pour dépasser certaines limites de cette approche, nous élaborons un nouvel outil pour l’apprentissage dans les réseaux spike, SpikeGrad, qui représente une implémentation entièrement évènementielle de la rétro-propagation du gradient. Nous montrons comment cette approche peut être utilisée pour l’entrainement d’un réseau spike qui est capable d’inférer des relations entre valeurs numériques et des images MNIST. Nous démontrons que cet outil est capable d’entrainer un réseau convolutif profond, qui donne des taux de reconnaissance d’image compétitifs avec l’état de l’art sur les bases de données MNIST et CIFAR10. De plus, SpikeGrad permet de formaliser la réponse d’un réseau spike comme celle d’un réseau de neurones artificiels classique, permettant un entraînement plus rapide.Nos travaux introduisent ainsi plusieurs mécanismes d’apprentissage puissants pour les réseaux évènementiels, contribuant à rendre l’apprentissage des réseaux spike plus adaptés à des problèmes réels
Inference and training in deep neural networks require large amounts of computation, which in many cases prevents the integration of deep networks in resource constrained environments. Event-based spiking neural networks represent an alternative to standard artificial neural networks that holds the promise of being capable of more energy efficient processing. However, training spiking neural networks to achieve high inference performance is still challenging, in particular when learning is also required to be compatible with neuromorphic constraints. This thesis studies training algorithms and information encoding in such deep networks of spiking neurons. Starting from a biologically inspired learning rule, we analyze which properties of learning rules are necessary in deep spiking neural networks to enable embedded learning in a continuous learning scenario. We show that a time scale invariant learning rule based on spike-timing dependent plasticity is able to perform hierarchical feature extraction and classification of simple objects of the MNIST and N-MNIST dataset. To overcome certain limitations of this approach we design a novel framework for spike-based learning, SpikeGrad, which represents a fully event-based implementation of the gradient backpropagation algorithm. We show how this algorithm can be used to train a spiking network that performs inference of relations between numbers and MNIST images. Additionally, we demonstrate that the framework is able to train large-scale convolutional spiking networks to competitive recognition rates on the MNIST and CIFAR10 datasets. In addition to being an effective and precise learning mechanism, SpikeGrad allows the description of the response of the spiking neural network in terms of a standard artificial neural network, which allows a faster simulation of spiking neural network training. Our work therefore introduces several powerful training concepts for on-chip learning in neuromorphic devices, that could help to scale spiking neural networks to real-world problems

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27

Nobliá, Matilda, and Christian Ryan. "Contamination Event Detection in Water Distribution Systems." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214698.

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In any society, making sure that its citizens havea clean water supply is a fundamental issue. By modernizingthe way water distribution systems (WDSs) are monitored andcontrolled, the impact of contamination can be maintained andminimized. By using sensors that monitor relevant physicalparameters, a system that detects contamination and limitspopulation exposure can be designed. To achieve this, the workpresented in this report is focused on three main topics.Firstly, parameters for determining water quality are examined.This is the basis for choosing relevant sensors. Secondly,a study of contamination event detection (CED) is presented, inparticular a method to determine whether water is contaminatedor not based on sensor measurements is proposed. This iscompleted through the use of binary hypothesis testing as wellas examining existing sensors. Thirdly, the problem of optimalsensor placement in a WDS is studied. In extension, a greedyalgorithm is implemented to optimally place sensors in a modelof real-world network.

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28

Caulkins, Bruce. "SESSION-BASED INTRUSION DETECTION SYSTEM TO MAP ANOMALOUS NETWORK TRAFFIC." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3466.

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Computer crime is a large problem (CSI, 2004; Kabay, 2001a; Kabay, 2001b). Security managers have a variety of tools at their disposal – firewalls, Intrusion Detection Systems (IDSs), encryption, authentication, and other hardware and software solutions to combat computer crime. Many IDS variants exist which allow security managers and engineers to identify attack network packets primarily through the use of signature detection; i.e., the IDS recognizes attack packets due to their well-known "fingerprints" or signatures as those packets cross the network's gateway threshold. On the other hand, anomaly-based ID systems determine what is normal traffic within a network and reports abnormal traffic behavior. This paper will describe a methodology towards developing a more-robust Intrusion Detection System through the use of data-mining techniques and anomaly detection. These data-mining techniques will dynamically model what a normal network should look like and reduce the false positive and false negative alarm rates in the process. We will use classification-tree techniques to accurately predict probable attack sessions. Overall, our goal is to model network traffic into network sessions and identify those network sessions that have a high-probability of being an attack and can be labeled as a "suspect session." Subsequently, we will use these techniques inclusive of signature detection methods, as they will be used in concert with known signatures and patterns in order to present a better model for detection and protection of networks and systems.
Ph.D.
Other
Arts and Sciences
Modeling and Simulation

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29

Lindberg, Therese. "Discrete Event Simulation of Bus Terminals." Licentiate thesis, Linköpings universitet, Kommunikations- och transportsystem, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-156646.

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Public transport is important to society as it provides spatial accessibility and reduces congestion and pollution in comparison to other motorized modes. To assure a high-quality service, all parts of the system need to be well-functioning and properly planned. One important aspect for the system's bus terminals is their capacity. This needs to be high enough to avoid congestion and queues and the delays these may lead to. During planning processes, various suggested designs and solutions for a terminal need to be evaluated. Estimating capacity and how well the suggestions will function is a challenging problem, however. It requires analysis of complex interactions and behaviour of the vehicles. This sort of analyses can preferably be carried out using microsimulation. Furthermore, a discrete event simulation approach can make use of the fact that the path of a vehicle through a terminal can readily be described by a sequence of events (such as arriving, starting to drive to a stop etc.). The overall aim of this thesis is to investigate how discrete event simulation can be used to evaluate bus terminal design and traffic control policies. The main contribution is the development of a method for bus terminal simulation. As a first step, a discrete event simulation model of a combined bus and tram stop is formulated. The model is tested on a real system where the current design is compared to an alternative one. The test shows that a model developed with a discrete event approach can be used to evaluate the situation at a stop and compare design alternatives. In the next step, a general discrete event simulation model of bus terminals is formulated. A modular approach is introduced, where a terminal can be constructed from a set of module building blocks. Another important contribution of the model is its spatial resolution that allows for queues and blockages to occur throughout the terminal. By applying the simulation model in a case study, it is shown that the model can be used to evaluate and compare various scenarios related to the layout, number of passengers and the outside traffic situation. Lastly, the bus terminal simulation model is used in a second case study in order to compare model output with empirical data. This study identified a number of factors that may have had an influence on differences between observations and simulation results and that is of interest to look further into. This includes the actual adherence to terminal rules and the effects of model parameters.

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30

Brito, Andrey. "Speculation in Parallel and Distributed Event Processing Systems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-38911.

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Event stream processing (ESP) applications enable the real-time processing of continuous flows of data. Algorithmic trading, network monitoring, and processing data from sensor networks are good examples of applications that traditionally rely upon ESP systems. In addition, technological advances are resulting in an increasing number of devices that are network enabled, producing information that can be automatically collected and processed. This increasing availability of on-line data motivates the development of new and more sophisticated applications that require low-latency processing of large volumes of data. ESP applications are composed of an acyclic graph of operators that is traversed by the data. Inside each operator, the events can be transformed, aggregated, enriched, or filtered out. Some of these operations depend only on the current input events, such operations are called stateless. Other operations, however, depend not only on the current event, but also on a state built during the processing of previous events. Such operations are, therefore, named stateful. As the number of ESP applications grows, there are increasingly strong requirements, which are often difficult to satisfy. In this dissertation, we address two challenges created by the use of stateful operations in a ESP application: (i) stateful operators can be bottlenecks because they are sensitive to the order of events and cannot be trivially parallelized by replication; and (ii), if failures are to be tolerated, the accumulated state of an stateful operator needs to be saved, saving this state traditionally imposes considerable performance costs. Our approach is to evaluate the use of speculation to address these two issues. For handling ordering and parallelization issues in a stateful operator, we propose a speculative approach that both reduces latency when the operator must wait for the correct ordering of the events and improves throughput when the operation in hand is parallelizable. In addition, our approach does not require that user understand concurrent programming or that he or she needs to consider out-of-order execution when writing the operations. For fault-tolerant applications, traditional approaches have imposed prohibitive performance costs due to pessimistic schemes. We extend such approaches, using speculation to mask the cost of fault tolerance.

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31

Svensson, Harari Natalia. "Manufacturing systems model interoperability in discrete event simulation." Thesis, KTH, Industriell produktion, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91591.

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The use of simulation has been said to be a useful tool to analyze manufacturing systems, Discrete Event Simulation - DES for instance under the occurrence of different events. Information management in Manufacturing Systems is an important issue and so it is insimulation studies because some of the difficulties in building, reusing and integratingsimulation models with other applications used in manufacturing systems are related withthe data. In this context different efforts have been made to facilitate the use of simulationand overcome interoperability problems through improving the information management,one of this is the Core Manufacturing Simulation Data Information Model - CMSDIMdeveloped by The National Institute of Standards and Technology - NIST. The objective of this thesis is to contribute to the use of the CMSDIM in ExtendSim V8. A method to import databases structured based on the CMSDIM into the Simulation softwareExtendSim V8 is developed and applied in a case study in a production line of SCANIA.

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32

Hashtrudi, Zad Shahin. "Fault diagnosis in discrete-event and hybrid systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/NQ45687.pdf.

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33

Estrada, Vargas Ana Paula, and Vargas Ana Paula Estrada. "Black-Box identification of automated discrete event systems." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2013. http://tel.archives-ouvertes.fr/tel-00846194.

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This thesis deals with the identification of automated discrete event systems (DES) operating in an industrial context. In particular the work focuses on the systems composed by a plant and a programmable logic controller (PLC) operating in a closed loop- the identification consists in obtaining an approximate model expressed in interpreted Petri nets (IPN) from the observed behaviour given under the form of a single sequence of input-output vectors of the PLC. First, an overview of previous works on identification of DES is presented as well as a comparative study of the main recent approaches on the matter. Then the addressed problem is stated- important technological characteristics of automated systems and PLC are detailed. Such characteristics must be considered in solving the identification problem, but they cannot be handled by previous identification techniques. The main contribution in this thesis is the creation of two complementary identification methods. The first method allows constructing systematically an IPN model from a single input-output sequence representing the observable behaviour of the DES. The obtained IPN models describe in detail the evolution of inputs and outputs during the system operation. The second method has been conceived for addressing large and complex industrial DES- it is based on a statistical approach yielding compact and expressive IPN models. It consists of two stages- the first one obtains, from the input-output sequence, the reactive part of the model composed by observable places and transitions. The second stage builds the non observable part of the model including places that ensure the reproduction of the observed input-output sequence. The proposed methods, based on polynomial-time algorithms, have been implemented in software tools, which have been tested with input-output sequences obtained from real systems in operation. The tools are described and their application is illustrated through two case studies.

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34

Clark, Kenneth A. "Modeling single-event transients in complex digital systems." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FClark%5FKenneth%5Fphd.pdf.

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35

Wen, Qin. "Fault-tolerant supervisory control of discrete-event systems." [Ames, Iowa : Iowa State University], 2009.

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36

Kammoun, Abderrahmen. "Enhancing Stream Processing and Complex Event Processing Systems." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSES012.

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Alors que de plus en plus d'objets et d'appareils sensoriels connectés font partie de notre vie quotidienne, la masse d'informations circulant à grande vitesse ne cesse d'augmenter. Cette énorme quantité de données produites à des débits élevés exige une compréhension rapide pour être utile dans divers domaines d'activité telles que l'internet des objets, la santé, la gestion de l'énergie, etc. Les techniques traditionnelles de stockage et de traitement de données se sont révélées inefficaces ou inadaptables pour gérer ce flux de données. Cette thèse a pour objectif de proposer des solutions optimales à deux problèmes de recherche sur la gestion de flux de données. La première concerne l’optimisation de la résolution de requêtes continues complexes par les systèmes de détection d'événements complexes (CEP). La seconde aux problèmes liées à la prédiction des événement complexes fondée sur l’apprentissage de l’historique du système. Premièrement, nous avons proposé un modèle de recalcul pour le traitement de requêtes complexes, basé sur une indexation multidimensionnelle et des algorithmes de jointures optimisés. Deuxièmement, nous avons conçu un CEP prédictif qui utilise des informations historiques pour prédire des événements complexes futurs. Pour utiliser efficacement l'information historique, nous utilisons un espace de séquences historiques à N dimensions. Par conséquent, la prédiction peut être effectuée en répondant aux requêtes d’intervalles sur cet espace de séquences historiques. La pertinence des résultats obtenus, notamment par l'application de nos algorithmes et approches lors de challenges internationaux démontre la viabilité des méthodes que nous proposons
As more and more connected objects and sensory devices are becoming part of our daily lives, the sea of high-velocity information flow is growing. This massive amount of data produced at high rates requires rapid insight to be useful in various applications such as the Internet of Things, health care, energy management, etc. Traditional data storage and processing techniques are proven inefficient. This gives rise to Data Stream Management and Complex Event Processing (CEP) systems.This thesis aims to provide optimal solutions for complex and proactive queries. Our proposed techniques, in addition to CPU and memory efficiency, enhance the capabilities of existing CEP systems by adding predictive feature through real-time learning. The main contributions of this thesis are as follows:We proposed various techniques to reduce the CPU and memory requirements of expensive queries. These operators result in exponential complexity both in terms of CPU and memory. Our proposed recomputation and heuristic-based algorithm reduce the costs of these operators. These optimizations are based on enabling efficient multidimensional indexing using space-filling curves and by clustering events into batches to reduce the cost of pair-wise joins.We designed a novel predictive CEP system that employs historical information to predict future complex events. We proposed a compressed index structure, range query processing techniques and an approximate summarizing technique over the historical space.The applicability of our techniques over the real-world problems presented has produced further customize-able solutions that demonstrate the viability of our proposed methods

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37

Mohror, Kathryn Marie. "Scalable event tracking on high-end parallel systems." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/2811.

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Accurate performance analysis of high end systems requires event-based traces to correctly identify the root cause of a number of the complex performance problems that arise on these highly parallel systems. These high-end architectures contain tens to hundreds of thousands of processors, pushing application scalability challenges to new heights. Unfortunately, the collection of event-based data presents scalability challenges itself: the large volume of collected data increases tool overhead, and results in data files that are difficult to store and analyze. Our solution to these problems is a new measurement technique called trace profiling that collects the information needed to diagnose performance problems that traditionally require traces, but at a greatly reduced data volume. The trace profiling technique reduces the amount of data measured and stored by capitalizing on the repeated behavior of programs, and on the similarity of the behavior and performance of parallel processes in an application run. Trace profiling is a hybrid between profiling and tracing, collecting summary information about the event patterns in an application run. Because the data has already been classified into behavior categories, we can present reduced, partially analyzed performance data to the user, highlighting the performance behaviors that comprised most of the execution time.

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38

Anozie, Chidi H. "Event-Triggered Design of Networked Embedded Automation Systems." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1291754351.

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39

Estrada, Vargas Ana Paula. "Black-Box identification of automated discrete event systems." Thesis, Cachan, Ecole normale supérieure, 2013. http://www.theses.fr/2013DENS0006/document.

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Cette thèse traite de l'identification des systèmes à événements discrets (SED) automatisés dans un contexte industriel. En particulier, le travail aborde les systèmes formés par un processus et un automate programmable (AP) fonctionnant en boucle fermée - l'identification a pour but d’obtenir un modèle approximatif exprimé en réseaux de Petri interprétés (RPI) à partir du comportement externe observé sous la forme d'une seule séquence de vecteurs d’entrée-sortie de l’AP. Tout d'abord, une analyse des méthodes d'identification est présentée, ainsi qu’une étude comparative des méthodes récentes pour l'identification des SED. Puis le problème abordé est décrit - des importantes caractéristiques technologiques dans les systèmes automatisés par l’AP sont détaillées. Ces caractéristiques doivent être prises en compte dans la résolution du problème, mais elles ne peuvent pas être traitées par les méthodes existantes d’identification. La contribution principale de cette thèse est la création de deux méthodes d’identification complémentaires. La première méthode permet de construire systématiquement un modèle RPI à partir d'une seule séquence entrée-sortie représentant le comportement observable du SED. Les modèles RPI décrivent en détail l’évolution des entrées et sorties pendant le fonctionnement du système. La seconde méthode considère des SED grands et complexes - elle est basée sur une approche statistique qui permettre la construction des modèles en RPI compactes et expressives. Elle est composée de deux étapes - la première calcule à partir de la séquence entrée-sortie, la partie réactive du modèle, constituée de places observables et de transitions. La deuxième étape fait la construction de la partie non-observable, en rajoutant des places pour permettre la reproduction de la séquence entrée-sortie. Les méthodes proposées, basées sur des algorithmes de complexité polynomiale, ont été implémentées en outils logiciels, lesquels ont été testés avec des séquences d’entrée-sortie obtenues à partir des systèmes réels en fonctionnement. Les outils sont décrits et leur application est illustrée à travers deux cas d’étude
This thesis deals with the identification of automated discrete event systems (DES) operating in an industrial context. In particular the work focuses on the systems composed by a plant and a programmable logic controller (PLC) operating in a closed loop- the identification consists in obtaining an approximate model expressed in interpreted Petri nets (IPN) from the observed behaviour given under the form of a single sequence of input-output vectors of the PLC. First, an overview of previous works on identification of DES is presented as well as a comparative study of the main recent approaches on the matter. Then the addressed problem is stated- important technological characteristics of automated systems and PLC are detailed. Such characteristics must be considered in solving the identification problem, but they cannot be handled by previous identification techniques. The main contribution in this thesis is the creation of two complementary identification methods. The first method allows constructing systematically an IPN model from a single input-output sequence representing the observable behaviour of the DES. The obtained IPN models describe in detail the evolution of inputs and outputs during the system operation. The second method has been conceived for addressing large and complex industrial DES- it is based on a statistical approach yielding compact and expressive IPN models. It consists of two stages- the first one obtains, from the input-output sequence, the reactive part of the model composed by observable places and transitions. The second stage builds the non observable part of the model including places that ensure the reproduction of the observed input-output sequence. The proposed methods, based on polynomial-time algorithms, have been implemented in software tools, which have been tested with input-output sequences obtained from real systems in operation. The tools are described and their application is illustrated through two case studies

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40

David-Henriet, Xavier. "Discrete Event Systems with Standard and Partial Synchronizations." Thesis, Angers, 2015. http://www.theses.fr/2015ANGE0010/document.

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De nombreux systèmes de transport peuvent être modélisées par des synchronisations ordinaires (pour tout k>=l, l'occurrence k de l'événement B se produit au moins t unités de temps après l'occurrence k-l de l'événement A). Ces systèmes sont linéaires dans l'algèbre (max,+). Pour certaines applications, il est primordial de modéliser la simultanéité entre événements. Comme la synchronisation ordinaire ne suffit pas à exprimer ce phénomène, nous introduisons la synchronisation partielle (l'événement B ne peut se produire que quand l'événement A se produit). Dans ce mémoire, des méthodes développées pour la modélisation et le contrôle de systèmes linéaires dans l'algèbre (max,+) sont étendues à des systèmes régis par des synchronisations ordinaires et partielles. Nous considérons uniquement des systèmes divisés en un système principal et un système secondaire et gouvernés par des synchronisations ordinaires entre événements dans le même système et des synchronisations partielles d'événements dans le système secondaire par des événements dans le système principal. Nous introduisons une commande optimale et une commande prédictive pour cette classe de systèmes par analogie avec les résultats disponibles pour les systèmes linéaires dans l'algèbre (max,+). En considérant un comportement donné pour le système principal, il est aussi possible de représenter le système secondaire par une fonction de transfert et de modifier sa dynamique pour suivre un modèle de référence
Many transportation networks can be modeled by (max,+)-linear systems, i.e., discrete event systems ruled by standard synchronizations (conditions of the form: "for all k>=l, occurrence k of event B is at least t units of time after occurrence k-l of event A"). In some applications, it is also necessary to model simultaneity between events (e.g., for a road equipped with traffic lights, a vehicle can cross an intersection only when the associated traffic light is green). Such conditions cannot be expressed using standard synchronizations. Hence, we introduce the partial synchronization (condition of the form: "event B can only occur when event A occurs"). In this thesis, we consider a class of discrete event systems ruled by standard and partial synchronizations, called (max,+)-systems with partial synchronization. Such systems are split into a main system and a secondary system such that there exist only standard synchronizations between events in the same system and partial synchronizations of events in the secondary system by events in the main system. We adapt some modeling and control approaches developed for (max,+)-linear systems to (max,+)-systems with partial synchronization. Optimal feedforward control and model predictive control for (max,+)-linear systems are extended to (max,+)-systems with partial synchronization. Furthermore, transfer relation and model reference control are provided for the secondary system under a predefined behavior of the main system

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41

Widebäck, West Nikolaus. "Multiple Session 3D Reconstruction using RGB-D Cameras." Thesis, Linköpings universitet, Datorseende, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-112799.

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In this thesis we study the problem of multi-session dense rgb-d slam for 3D reconstruc- tion. Multi-session reconstruction can allow users to capture parts of an object that could not easily be captured in one session, due for instance to poor accessibility or user mistakes. We first present a thorough overview of single-session dense rgb-d slam and describe the multi-session problem as a loosening of the incremental camera movement and static scene assumptions commonly held in the single-session case. We then implement and evaluate sev- eral variations on a system for doing two-session reconstruction as an extension to a single- session dense rgb-d slam system. The extension from one to several sessions is divided into registering separate sessions into a single reference frame, re-optimizing the camera trajectories, and fusing together the data to generate a final 3D model. Registration is done by matching reconstructed models from the separate sessions using one of two adaptations on a 3D object detection pipeline. The registration pipelines are evaluated with many different sub-steps on a challenging dataset and it is found that robust registration can be achieved using the proposed methods on scenes without degenerate shape symmetry. In particular we find that using plane matches between two sessions as constraints for as much as possible of the registration pipeline improves results. Several different strategies for re-optimizing camera trajectories using data from both ses- sions are implemented and evaluated. The re-optimization strategies are based on re- tracking the camera poses from all sessions together, and then optionally optimizing over the full problem as represented on a pose-graph. The camera tracking is done by incrementally building and tracking against a tsdf volume, from which a final 3D mesh model is extracted. The whole system is qualitatively evaluated against a realistic dataset for multi-session re- construction. It is concluded that the overall approach is successful in reconstructing objects from several sessions, but that other fine grained registration methods would be required in order to achieve multi-session reconstructions that are indistinguishable from singe-session results in terms of reconstruction quality.

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Abdelrahim, Mahmoud. "Output feedback event-triggered control." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0110/document.

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La commande à transmissions événementielles est une approche dans laquelle les instants de transmission sont définis selon un critère dépendant de l'état du système et non plus d'une horloge à l'instar des implantations périodiques. Dans cette thèse, nous nous concentrons sur la synthèse de telles lois de commande par retour de sortie. Les contributions sont les suivantes : (i) nous proposons une méthode de synthèse dite par émulation pour des systèmes non linéaires; (ii) nous présentons une méthode de synthèse jointe de la loi de commande et de la condition de déclenchement pour les systèmes linéaires; (iii) nous nous intéressons au cas de systèmes non linéaires singulièrement perturbés et nous construisons le contrôleur à partir d’approximation de la dynamique lente uniquement
Event-triggered control is a sampling paradigm in which the sequence of transmission instants is determined based on the violation of a state-dependent criterion and not a time-driven clock. In this thesis, we deal with event-triggered output-based controllers to stabilize classes of nonlinear systems. The contributions of the presented material are threefold: (i) we stabilize a class of nonlinear systems by using an emulation-based approach; (ii) we develop a co-design procedure to simultaneously design the output feedback law and the event-triggering condition for linear systems; (iii) we propose stabilizing event-triggered controllers for nonlinear systems whose dynamics have two-time scales (in particular, we only rely on the knowledge of an approximate model of the slow dynamics)

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Sampath, Sreedevi. "Cost-effective techniques for user-session-based testing of Web applications." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.02 Mb., 169 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220722.

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Pålsson, Jonatan. "Querying Federations of Eiffel Event Data Repositories." Thesis, Linköpings universitet, Databas och informationsteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-169138.

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The goal of this thesis was to find out if Eiffel event data could be represented in a RDF format and to be able to query this data effectively in a federation of SPARQL endpoints. The Eiffel data was created by a provided generator from the Eiffel project which the author extended in order to create links between datasets. These new datasets were then converted into RDF triples and uploaded to two separate SPARQL endpoints in Azure. Two types of SPARQL federation engine types were used to query this data, index-based and index-free. The index-based systems were not able to produce any measurable results unfortunately, however the index-free system FedX was able to. This gives proof that Eiffel data can be represented in RDF format in order for a index-free engine to query on a SPARQL federation containing datasets of this data. It is however difficult to provide proof of effectiveness without having another system to compare to.

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Gardner, Robert David. "Event handling techniques in high speed networks." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248548.

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Myadzelets, Dmitry <1974&gt. "Discrete Event Systems based Design Patterns for Diagnosability Analysis of Automated Manufacturing Systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6335/.

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The main goal of this thesis is to facilitate the process of industrial automated systems development applying formal methods to ensure the reliability of systems. A new formulation of distributed diagnosability problem in terms of Discrete Event Systems theory and automata framework is presented, which is then used to enforce the desired property of the system, rather then just verifying it. This approach tackles the state explosion problem with modeling patterns and new algorithms, aimed for verification of diagnosability property in the context of the distributed diagnosability problem. The concepts are validated with a newly developed software tool.

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Egilsson, Guðlaugur Stefán. "Event Models : An Evaluation Framework." Thesis, University of Skövde, Department of Computer Science, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-389.

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Event based programming is an important metaphor used in a variety of applications. Research and practice in this field comes primarily from two distinct sources, component software and databases. In both those fields, the need for asynchronous notifications has led to the specification and implementation of event models, but with somewhat different emphasis.

This dissertation defines an evaluation framework for evaluating event models. In doing so, it defines several factors that are important when reviewing different event models with respect to implementing applications or components that require event notification mechanisms.

It has been suggested that the event models defined for COM and CORBA can each be used as the basis for implementing advanced event services. The framework presented in this dissertation is used to evaluate these two event models with respect to their capability to support an advanced event service originating from active database research.

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Ye, Lina. "Optimized diagnosability of distributed discrete event systems through abstraction." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00635695.

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Depuis plusieurs années, de nombreuses recherches ont été menées autour du diagnostic. Cependant, il est impératif de se préoccuper dès la phase de conception d'un système des objectifs de diagnostic à atteindre. Aussi, de nombreux travaux se sont intéressés à analyser et à caractériser les propriétés de la diagnosticabilité d'un système. La diagnosticabilité est la propriété d'un système garantissant qu'il génère des observations permettant de détecter et discriminer les fautes en temps fini après leur occurrence.Le sujet de cette thèse porte sur les méthodes permettant d'établir les propriétés de la diagnosticabilité des systèmes à événements discrets dans le cadre distribué, sans construction du modèle global du système. Ce cadre est de première importance pour les applications réelles : systèmes naturellement distribués, systèmes trop complexes pour traiter leur modèle global, confidentialité des modèles locaux les uns par rapport aux autres. L'analyse de la diagnosticabilité de tels systèmes distribués se fonde sur des opérations de synchronisation des modèles locaux, par les observations et les communications. D'abord, nous étudions comment optimiser cette analyse de la diagnosticabilité en faisant abstraction de l'information nécessaire et suffisante à partir des objets locaux pour décider la diagnosticabilité globale. L'efficacité de l'algorithme peut être grandement améliorée par la synchronisation des objets locaux et abstraits en comparaison avec celle des objets locaux et non abstraits.Ensuite, nous proposons, dans le cadre distribué, l'algorithme de la diagnosticabilité de motifs d'événements particuliers a priori inobservables dans les systèmes. Ces motifs peuvent être simplement l'occurrence, brutale ou graduelle, d'une faute permanente ou transitoire, plusieurs occurrences d'une faute, plusieurs fautes en cascade, etc. Dans le cadre distribué, la reconnaissance du motif d'événements s'effectue d'abord progressivement dans un sous-système et ensuite la diagnosticabilité de ce motif peut être déterminée par la méthode abstraite et distribuée. Nous prouvons la correction et l'efficacité de notre algorithme à la fois en théorie et en pratique par la mise en œuvre de l'implémentation sur des exemples.Finalement, nous étudions le problème de la diagnosticabilité dans les systèmes distribués avec composants autonomes, où l'information observable est distribuée au lieu d'être centralisée comme jusqu'alors. En d'autres termes, chaque composant ne peut appréhender que ses propres événements observables. Nous donnons la définition de la diagnosticabilité conjointe. Et puis nous discutons de l'indécidabilité de diagnosticabilité conjointe dans le cas général, c'est à dire, les événements de communication ne sont pas observables, avant de proposer un algorithme pour tester sa condition suffisante. De plus, nous obtenons également un résultat de décidabilité et de l'algorithme lorsque les communications sont observables.

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Posse, Ernesto. "Modelling and simulation of dynamic-structure discrete-event systems." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22006.

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Discrete-event modelling and simulation has become an established approach to the description and study of complex dynamic systems. In recent years there has been an increased interest in modelling complex dynamic-structure systems, i.e., systems whose structure changes over time. Such systems are generally more difficult to understand and analyze than systems with a static structure. These challenges can be met by the development of appropriate modelling formalisms based on a solid foundation and with suitable supporting tools. In this thesis we explore an approach to modelling and simulation of dynamic-structure discrete-event systems based on process algebra. The thesis consists of two parts. We begin by exploring, in the first part, a formalism for static-structure discrete-event modelling and simulation called the Discrete-EVent System Specification formalism (DEVS [Zeigler 76, 2000].) We develop an alternative theoretical foundation for DEVS based on Structural Operational Semantics, focusing on determinism and compositionality properties. In the second part we develop a modelling language for dynamic-structure discrete-event systems named kiltera, based on process algebras and incorporating elements from discrete-event modelling. This language, based on the \pi-calculus [Milner 89], allows us to describe and reason about timed, mobile and distributed discrete-event systems in a single framework. We develop a theoretical foundation based on Structural Operational Semantics and establish fundamental properties concerning time-determinism, continuity, compositionality and legitimacy. We build a simulator for the language which supports both sequential and distributed execution of models, based on a variant of the Time Warp algorithm [Jefferson 85]. Finally we apply this language to the modelling and simulation of traffic.
La modélisation et la simulation à événements discrets constituent une approche bien établie pour la description et l'étude des systèmes dynamiques complexes. Ces dernières années, il y a eu un regain d'intérêt pour la modélisation des systèmes complexes à structure dynamique. Ces systèmes sont généralement plus difficiles à comprendre et à analyser que les systèmes ayant une structure statique. Cette analyse et cette compréhension peuvent être développées à l'aide de formalismes de modélisation fondés sur une base solide et des outils appropriés. Dans cette thèse, nous explorons une approche de modélisation et de simulation des systèmes à événements discrets fondée sur l'algèbre de processus. Ce document se compose de deux parties. Dans la première partie, nous étudions ce que l'on appelle le formalisme Discrete-EVent System Specifications (DEVS.) Nous développons un autre fondement théorique pour DEVS fondée sur la sémantique opérationnelle structurelle, en mettant l'accent sur les propriétés de déterminisme et de compositionalité. Dans la deuxième partie, nous développons un langage de modélisation pour systèmes à structure dynamique nommé kiltera, en nous fondant sur les algèbres de processus et en incorporant des éléments de modélisation à événements discrets. Ce langage, en se fondant sur le \pi-calcul, nous permet de décrire et de raisonner sur les systèmes mobiles, distribués et au temps-réel, à événements discrets, dans un cadre conceptuel unique. Nous développons une base théorique fondée sur la sémantique opérationnelle structurelle et nous établissons des propriétés fondamentales concernant le déterminisme-temps, la continuité, la compositionalité et la légitimité. Nous construisons un simulateur pour le langage qui supporte à la fois l'exécution séquentielle et distribuée de modèles, en utilisant une variante de l'algorithme Time Warp. Enfin, nous appliquons ce la

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Rönn, Pernilla. "Two Approaches to Event Detection in Active Database Systems." Thesis, University of Skövde, Department of Computer Science, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-628.

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An active database management system can react to predefined events in the database, resulting in performing some appropriate action. ECA-rules are used to capture these predefined events and to express the appropriate action in the active database management system. An event is said to be an atomic occurrence and is either primitive or composite. D-SNOOP and O-SNOOP are two ways to describe the semantics of composite events. D-SNOOP is detection-based (an event is considered to be instantaneous) and O-SNOOP occurrence-based (an event is considered to occur over a time interval). Some problems concerning the detection of composite events using D-SNOOP semantics have been highlighted by Galton and Augusto (2001), who have created the O-SNOOP semantics to rectify some of the shortcomings of D-SNOOP. It is, however, not known what practical consequences O-SNOOP has on applications. To find some of these practical consequences, an advanced application that uses composite events must be used. In this work, the advanced application is a cooperative information system.

A cooperative information system is a system in which several agents work together to solve some common problem. The agents can take on a role as either manager (service requester) or agent (problem solver).

In this dissertation an investigation of the differences between O-SNOOP and D-SNOOP in applications handling cooperation protocols is presented. Our first objective has been to model a cooperation protocol using in turn the D-SNOOP and the O-SNOOP semantics. A further objective has been to compare the models of the cooperation protocols to identify any differences between using D-SNOOP and O-SNOOP semantics in applications handling cooperation protocols.

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Дисертації з теми "Session and event systems"

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