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Skalierbare agentenbasierte Simulation: Werkzeuge und Techniken zur verteilten Ausführung agentenbasierter Modelle
No full textAbstract
Pawlaszczyk, Dirk:
Skalierbare agentenbasierte Simulation : Werkzeuge und Techniken zur verteilten
Ausführung agentenbasierter Modelle / Dirk Pawlaszczyk
Ilmenau : Univ.-Verl. Ilmenau, 2009. - XVI, 327 S.
ISBN 978-3-939473-59-6
Research on systems of autonomous agents, called multiagent systems (MAS), has
received much interest in the domain of (distributed) artificial intelligence
in recent years. MAS are most suitable for the development of distributed
applications with uncertain and a dynamically changing environment. Simulation
is the imitation of a systems behaviour and structure in an experimental model
to reach findings which are transferable to reality. In multiagent-based
simulation (MABS) real world systems are modelled using multiple agents.
The system emerges by interaction of the individual agents as well as their
collective behaviour. Agents send messages with respect to some communication
protocol and are disposed at some discrete point in time. In this context a
software agent is defined as a program that acts autonomously, communicates
with other agents, is goal-oriented (pro-active) and uses explicit knowledge.
Agent-based modelling and simulation seems to be the right tool for domains
characterized by discrete decisions and distributed local decision makers. MABS
is an appropriate method if we wish to understand the evolution of a
distributed system, minted with non-linear dynamics. As we wish to resemble
this complex real world system, there is an increasing demand to simulate large
models, composed with hundreds or even more agents. With growing complexity,
the scalability of a simulation environment becomes a crucial measure of its
ability to cope with the complexity of the underlying system. To simulate an
increasing number of entities, the underlying simulation system needs to be
scaleable. Since agent-based simulation moves out of the academic world towards
commercial applications it becomes certainly demanding to investigate in
scalability issues. The objective of this thesis is to discuss an approach for
scalable simulation, which considers the deviations of agent-based simulation
approach effectively. Therefore, we outline some commonly used notions of
scalability and begin to examine what scalability means within the context of
agent-based simulation. Furthermore we introduce the concept of a scalable time
management service. With respect to the experimental results it is argued that
parallel and distributed simulation can help to ensure scaleable simulation of
agent based models.Zusammenfassung:
Simulation stellt eine Analysemethode für viele Anwendungsbereiche zur Verfügung. Im Mittelpunkt der vorliegenden Arbeit steht eine spezielle Simulationsmethode - die Agentenbasierte Simulation (ABS). Im Rahmen der ABS werden Modelle betrachtet, die sich aus Agenten zusammensetzen. Agenten sind in der Lage, ihre Umgebung wahrzunehmen und unter Rückgriff auf lokal hinterlegtes Wissen, Schlüsse über ihre Wahrnehmungen ziehen. Darauf aufbauend wählt ein Agent Aktionen aus, mit denen er seine Umwelt gezielt verändern kann. Neben ihrer Autonomie sind Software-Agenten häufig durch soziale Eigenschaften charakterisiert und der Fähigkeit benachbarte Systeme zu erkennen und mit diesen zu kommunizieren. Agentenbasierte Simulation erlaubt es, das Verhalten komplexer Systeme sowie emergente Phänomene zu studieren. Die Komplexität der mittels Agententechnologie zu lösenden Problemstellungen und die Größe der zu simulierenden Modelle nehmen stetig zu. Auf der anderen Seite wird der Entwicklung von Werkzeugen zur effizienten Durchführung von agentenbasierten Simulationsexperimenten bisher vergleichsweise wenig Beachtung geschenkt. Die verteilte Simulation versucht, unabhängige Ereignisse nebenläufig auszuführen, um so die Simulationsexperimente zu beschleunigen und die Effizienz zu verbessern. Die Ansätze der verteilten Simulation sind jedoch vielfältig. Die Auswahl des richtigen Verfahrens fällt schwer.
Die vorliegende Dissertation diskutiert Strategien zur Parallelisierung agentenbasierter Simulation. Ziel der Arbeit ist es, Chancen und Risiken die durch die Verteilung von Agentenmodellen entstehen näher zu untersuchen. Insbesondere werden Möglichkeiten sowie Grenzen der Skalierung dieser Anwendungsklasse analysiert. Hierfür wird zunächst der Begriff der Skalierbarkeit eingeführt. Mit ihrer Hilfe ist es möglich, Aussagen über die Effizienz eines verteilten Systems zu treffen. Die Entwicklung und Erprobung neuer sowie die Untersuchung bestehender Verfahren für die verteilte Simulation und deren Übertragung auf den Bereich der agentenbasierten Simulation bilden weitere Schwerpunkte der Arbeit
Mobile Forensics – The File Format Handbook
No full textThis open access book summarizes knowledge about several file systems and file formats commonly used in mobile devices. In addition to the fundamental description of the formats, there are hints about the forensic value of possible artefacts, along with an outline of tools that can decode the relevant data. The book is organized into two distinct parts: Part I describes several different file systems that are commonly used in mobile devices. · APFS is the file system that is used in all modern Apple devices including iPhones, iPads, and even Apple Computers, like the MacBook series. · Ext4 is very common in Android devices and is the successor of the Ext2 and Ext3 file systems that were commonly used on Linux-based computers. · The Flash-Friendly File System (F2FS) is a Linux system designed explicitly for NAND Flash memory, common in removable storage devices and mobile devices, which Samsung Electronics developed in 2012. · The QNX6 file system is present in Smartphones delivered by Blackberry (e.g. devices that are using Blackberry 10) and modern vehicle infotainment systems that use QNX as their operating system. Part II describes five different file formats that are commonly used on mobile devices. · SQLite is nearly omnipresent in mobile devices with an overwhelming majority of all mobile applications storing their data in such databases. · The second leading file format in the mobile world are Property Lists, which are predominantly found on Apple devices. · Java Serialization is a popular technique for storing object states in the Java programming language. Mobile application (app) developers very often resort to this technique to make their application state persistent. · The Realm database format has emerged over recent years as a possible successor to the now ageing SQLite format and has begun to appear as part of some modern applications on mobile devices. · Protocol Buffers provide a format for taking compiled data and serializing it by turning it into bytes represented in decimal values, which is a technique commonly used in mobile devices. The aim of this book is to act as a knowledge base and reference guide for digital forensic practitioners who need knowledge about a specific file system or file format. It is also hoped to provide useful insight and knowledge for students or other aspiring professionals who want to work within the field of digital forensics. The book is written with the assumption that the reader will have some existing knowledge and understanding about computers, mobile devices, file systems and file formats
Mobile Forensics – The File Format Handbook
Full text linkThis open access book summarizes knowledge about several file systems and file formats commonly used in mobile devices. In addition to the fundamental description of the formats, there are hints about the forensic value of possible artefacts, along with an outline of tools that can decode the relevant data. The book is organized into two distinct parts: Part I describes several different file systems that are commonly used in mobile devices. · APFS is the file system that is used in all modern Apple devices including iPhones, iPads, and even Apple Computers, like the MacBook series. · Ext4 is very common in Android devices and is the successor of the Ext2 and Ext3 file systems that were commonly used on Linux-based computers. · The Flash-Friendly File System (F2FS) is a Linux system designed explicitly for NAND Flash memory, common in removable storage devices and mobile devices, which Samsung Electronics developed in 2012. · The QNX6 file system is present in Smartphones delivered by Blackberry (e.g. devices that are using Blackberry 10) and modern vehicle infotainment systems that use QNX as their operating system. Part II describes five different file formats that are commonly used on mobile devices. · SQLite is nearly omnipresent in mobile devices with an overwhelming majority of all mobile applications storing their data in such databases. · The second leading file format in the mobile world are Property Lists, which are predominantly found on Apple devices. · Java Serialization is a popular technique for storing object states in the Java programming language. Mobile application (app) developers very often resort to this technique to make their application state persistent. · The Realm database format has emerged over recent years as a possible successor to the now ageing SQLite format and has begun to appear as part of some modern applications on mobile devices. · Protocol Buffers provide a format for taking compiled data and serializing it by turning it into bytes represented in decimal values, which is a technique commonly used in mobile devices. The aim of this book is to act as a knowledge base and reference guide for digital forensic practitioners who need knowledge about a specific file system or file format. It is also hoped to provide useful insight and knowledge for students or other aspiring professionals who want to work within the field of digital forensics. The book is written with the assumption that the reader will have some existing knowledge and understanding about computers, mobile devices, file systems and file formats
Mobile Forensics – The File Format Handbook
Full text linkThis open access book summarizes knowledge about several file systems and file formats commonly used in mobile devices. In addition to the fundamental description of the formats, there are hints about the forensic value of possible artefacts, along with an outline of tools that can decode the relevant data. The book is organized into two distinct parts: Part I describes several different file systems that are commonly used in mobile devices. · APFS is the file system that is used in all modern Apple devices including iPhones, iPads, and even Apple Computers, like the MacBook series. · Ext4 is very common in Android devices and is the successor of the Ext2 and Ext3 file systems that were commonly used on Linux-based computers. · The Flash-Friendly File System (F2FS) is a Linux system designed explicitly for NAND Flash memory, common in removable storage devices and mobile devices, which Samsung Electronics developed in 2012. · The QNX6 file system is present in Smartphones delivered by Blackberry (e.g. devices that are using Blackberry 10) and modern vehicle infotainment systems that use QNX as their operating system. Part II describes five different file formats that are commonly used on mobile devices. · SQLite is nearly omnipresent in mobile devices with an overwhelming majority of all mobile applications storing their data in such databases. · The second leading file format in the mobile world are Property Lists, which are predominantly found on Apple devices. · Java Serialization is a popular technique for storing object states in the Java programming language. Mobile application (app) developers very often resort to this technique to make their application state persistent. · The Realm database format has emerged over recent years as a possible successor to the now ageing SQLite format and has begun to appear as part of some modern applications on mobile devices. · Protocol Buffers provide a format for taking compiled data and serializing it by turning it into bytes represented in decimal values, which is a technique commonly used in mobile devices. The aim of this book is to act as a knowledge base and reference guide for digital forensic practitioners who need knowledge about a specific file system or file format. It is also hoped to provide useful insight and knowledge for students or other aspiring professionals who want to work within the field of digital forensics. The book is written with the assumption that the reader will have some existing knowledge and understanding about computers, mobile devices, file systems and file formats
Skalierbare Agentenbasierte Simulation – Verteilte Simulation agentenbasierter Modelle
No full textDie Parallelisierung von Anwendungen, d.h. das Zerlegen eines Anwendungsproblems in Teilprobleme, die von mehreren Prozessen getrennt bearbeitet werden können, wird in der Verteilten Künstlichen Intelligenz ebenso wie in der Simulationstechnik seit vielen Jahren diskutiert. Innerhalb der VKI sind die Forscher vorrangig an flexiblen Problemlösungstrategien und Komplexitätsreduktion interessiert. Im Rahmen der Simulationstechnik wird zumeist eine Beschleunigung von Experimenten durch Verteilung angestrebt. In diesem Beitrag werden Strategien zur Parallelisierung von Simulationsmodellen und deren praktische Anwendbarkeit für die agentenbasierte Simulation vorgestellt. Außerdem werden Möglichkeiten und Grenzen der Skalierung dieser speziellen Anwendungsklasse diskutiert
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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