Dissertations / Theses on the topic 'Abstraction'
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Huang, Shan Shan. "Structural abstraction." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29632.
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Thesis (Ph.D)--Computing, Georgia Institute of Technology, 2010.Committee Chair: Yannis Smaragdakis; Committee Member: Oege de Moor; Committee Member: Richard LeBlanc; Committee Member: Santosh Pande; Committee Member: Spencer Rugaber. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Payne, Jonathan. "Expansionist abstraction." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/3326/.
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The subject of this thesis is a position in the philosophy of mathematics - defended by Bob Hale and Crispin Wright - known variously as neo-Fregeanism, neo-Logicism or abstractionism, and which claims that knowledge of mathematical objects can be based on principles - known as abstraction principles - which are in important respects like definitions of mathematical language. In the thesis, I make a distinction between two ways in which the abstraction programme might be carried out. These are the standardly defended static view, according to which abstraction principles can used to discover previously unrecognised objects lying within some fixed domain of quantification. The second is an expansionist view, according to which abstraction principles allow one to introduce new quantificational vocabulary, and thus expand ones domain of quantification to one which contains referents of mathematical terms. There are then two main aims. The first is to examine the static position, so as to identify the components of that view which make it committed to a standard domain, and to argue against the view. My main argument against the view concerns what has become known as the bad company problem. I argue that there is an epistemological component to the bad company problem which can not be avoided by the static abstractionist. The second aim of the thesis is to argue for and defend the expansionist view. In particular, I will claim that the expansionist view avoids the bad company problem, and that the expansionist view allows for an abstractionist foundation for set theory - an aim which (or so I will argue) has so far eluded the static view.
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Stewart, Nicholas. "Abstraction and comedy." Thesis, Goldsmiths College (University of London), 2013. http://research.gold.ac.uk/9922/.
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The thesis, consisting of an extended artwork (Toy Zoo) and a theoretical text, aims to explore a concept of abstraction and relate this concept to an affect of comedy. The proposal of the thesis is that abstraction, looked at in a proper way, is funny. Abstraction is imagined not as the absence of ‘content’ or the generalization of form, but as a condition of language occasioned by a categorical loss, the loss of the ground that attaches meaning to a thing. The work takes this dissonance in language as its subject-matter. In a series of photographic images, representations of mental or conceptual objects whose mode of representation alters the meaning of the term, it presents abstraction not as a formal reduction or the presentation of a higher order but as the historical view of a void subject-position. Its argument is that the view from this position is comic. The text develops a concept of abstraction from Hegel’s description of ‘the abstract work of art’. This ‘absolute’ abstraction, a condition in society to which art responds, is the premise through which various forms of abstract production, in art and elsewhere, are read. The generic forms of the epic, tragedy and comedy, as analyzed by Hegel, provide models that are applied in the context of ‘real abstraction’ and to certain positions in art. An analysis of value in capital aims to identify the logic of this form of production with the structure of tragedy. Against this ‘ready-made’ abstraction of modernity, the non-dialectical relationship of abstract necessity and the individual, the text argues for a form of comedy. Comedy, as a genre in art, proposes a subject-position that, recognizing itself in abstraction, recognizes abstraction not, as in ‘real abstraction’, as necessity but as the condition of its own freedom.
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Rayside, Derek F. "Automating abstraction functions." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62439.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 109-119).
Data abstraction has been the dominant structuring paradigm for programs for decades. The essence of a data abstraction is the abstraction function, which relates the concrete program representation to its abstract meaning. However, abstraction functions are not generally considered to be a part of the executing program. We propose that making abstraction functions an executable part of the program can enable programmers to write clearer and more concise programs with fewer errors. In particular, we show that the object equality and hashing operations (which programmers are required to write), can often be expressed more clearly and more concisely in terms of the abstract state of the object. Getting these methods right has proven to be difficult for programmers at all skill levels, from novice through expert. In a case study of the standard Java libraries we show that rewriting the code with explicit declarative abstraction functions (and generating equality and hashing methods automatically) removed object-contract compliance faults previously found by Pacheco et al. To make abstraction functions part of the executing program we develop four techniques for the dynamic evaluation of abstraction functions written in a declarative first-order logic with relations and transitive closure. We observe that the abstraction functions programmers write in practice may often be viewed as navigation queries on the heap, and two of our techniques exploit this insight to synthesize executable code from declarative abstraction functions. The performance of our research prototype is within striking distance of hand-written code.
by Derek F. Rayside.
Ph.D.
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Koniski, Grant. ""The Unprogrammed Abstraction"." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592135457002889.
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Barthélemy, Anne. "Abstraction et photographie /." [Rennes] : l'auteur, 1997. http://catalogue.bnf.fr/ark:/12148/cb370661876.
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Girgin, Sertan. "Abstraction In Reinforcement Learning." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608257/index.pdf.
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Reinforcement learning is the problem faced by an agent that must learn behavior through trial-and-error interactions with a dynamic environment. Generally, the problem to be solved contains subtasks that repeat at different regions of the state space. Without any guidance an agent has to learn the solutions of all subtask instances independently, which degrades the learning performance.
In this thesis, we propose two approaches to build connections between different regions of the search space leading to better utilization of gained experience and accelerate learning is proposed. In the first approach, we first extend existing work of McGovern and propose the formalization of stochastic conditionally terminating sequences with higher representational power. Then, we describe how to efficiently discover and employ useful abstractions during learning based on such sequences. The method constructs a tree structure to keep track of frequently used action sequences together with visited states. This tree is then used to select actions to be executed at each step.
In the second approach, we propose a novel method to identify states with similar sub-policies, and show how they can be integrated into reinforcement learning framework to improve the learning performance. The method uses an efficient data structure to find common action sequences started from observed states and defines a similarity function between states based on the number of such sequences. Using this similarity function, updates on the action-value function of a state are reflected to all similar states. This, consequently, allows experience acquired during learning be applied to a broader context.
Effectiveness of both approaches is demonstrated empirically by conducting extensive experiments on various domains.
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Smirnov, Sergey. "Business process model abstraction." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/6025/.
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Business process models are used within a range of organizational initiatives, where every stakeholder has a unique perspective on a process and demands the respective model. As a consequence, multiple process models capturing the very same business process coexist. Keeping such models in sync is a challenge within an ever changing business environment: once a process is changed, all its models have to be updated. Due to a large number of models and their complex relations, model maintenance becomes error-prone and expensive. Against this background, business process model abstraction emerged as an operation reducing the number of stored process models and facilitating model management. Business process model abstraction is an operation preserving essential process properties and leaving out insignificant details in order to retain information relevant for a particular purpose. Process model abstraction has been addressed by several researchers. The focus of their studies has been on particular use cases and model transformations supporting these use cases.
This thesis systematically approaches the problem of business process model abstraction shaping the outcome into a framework. We investigate the current industry demand in abstraction summarizing it in a catalog of business process model abstraction use cases. The thesis focuses on one prominent use case where the user demands a model with coarse-grained activities and overall process ordering constraints. We develop model transformations that support this use case starting with the transformations based on process model structure analysis. Further, abstraction methods considering the semantics of process model elements are investigated. First, we suggest how semantically related activities can be discovered in process models-a barely researched challenge. The thesis validates the designed abstraction methods against sets of industrial process models and discusses the method implementation aspects. Second, we develop a novel model transformation, which combined with the related activity discovery allows flexible non-hierarchical abstraction. In this way this thesis advocates novel model transformations that facilitate business process model management and provides the foundations for innovative tool support.Geschäftsprozessmodelle werden in einer Fülle organisatorischer Initiativen eingesetzt, wobei verschiedene Stakeholder individuelle Ansprüche an die Sicht auf den jeweiligen Prozess haben. Dies führt dazu, dass zu einem Geschäftsprozess eine Vielzahl unterschiedlicher Modelle existiert. In einer sich ständig verändernden Geschäftsumgebung ist es daher schwierig, diese Vielzahl von Modellen konsistent zu halten: Ändert sich sich ein Prozess, müssen alle Modelle, die ihn beschreiben, aktualisiert werden. Aufgrund der schieren Menge an Prozessmodellen und ihrer komplexen Beziehungen zueinander, erhöhen sich Aufwand und Kosten zur Pflege aller Modelle enorm. Vor diesem Hintergrund ermöglicht die Abstraktion von Geschäftsprozessmodellen, die Menge der Modelle zu reduzieren und damit ihre Verwaltung zu vereinfachen. Abstraktion von Geschäftsprozessmodellen bezeichnet eine Transformation eines Prozessmodells, so dass es für einen bestimmten Zweck besonders geeignet ist. Bei der Abstraktion von Geschäftsprozessen bleiben essentielle Eigenschaften eines Modells erhalten, während irrelevante Eigenschaften verworfen werden. Mehrere Studien stellen Prozessmodellabstraktion in den Fokus und konzentrieren sich auf konkrete Anwendungsfälle, für die sie geeignete Transformationen entwickelt haben. Diese Dissertation untersucht das Problem der Prozessmodellabstraktion und systematisiert die Lösung in einem Framework. Aktuelle Anforderungen der Industrie an die Abstraktion von Prozessmodellen wurden recherchiert und in einem Katalog von Anwendungsfällen zusammengefasst, von denen ein besonderer für die weiteren Untersuchungen ausgewählt wurde. In diesem Fall erwartet der Nutzer ein Modell niedrigeren Detailgrades, in welchem die Kontrollflussbeziehungen des Ursprungsmodells erhalten bleiben. Beginnend bei Modelltransformationen, die auf der Analyse der Prozessmodellstruktur aufbauen, entwickeln wir neuartige Abstraktionsoperationen zur Unterstützung dieses Anwendungsfalles. Darüber hinaus untersuchen wir Abstraktionsmethoden, welche die Semantik von Prozessmodellelementen berücksichtigen. Zum einen zeigen wir, wie Aktivitäten ermittelt werden können, die miteinander in semantischer Beziehung stehen - ein Problem, das bisher nur unzureichend betrachtet wurde. Die vorgeschlagenen Methoden werden mithilfe industrieller Prozessmodellsammlungen validiert und deren Umsetzung diskutiert. Zum anderen schlagen wir eine innovative Modelltransformation zur nicht-hierarchischen Abstraktion von Prozessmodellen vor. Dieser liegt die Ermittlung in Beziehung stehender Aktivitäten zugrunde. Demzufolge präsentiert diese Arbeit eine originäre Methode zur Prozessmodellabstraktion, die die Verwaltung von Geschäftsprozessmodellen vereinfacht und den Grundstein für innovative Softwarewerkzeuge legt.
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Clark, Allan. "Abstraction-level functional programming." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/24458.
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This thesis is concerned with the abstraction-level programming, where abstraction-level is the level of programming tasks which extend the abstraction of the machine. Extending the abstraction of the machine is generally done by compiler writers for high-level programming languages or those implementing an interface to lower-level or legacy libraries. The abstractions which are implemented are then used, either explicitly or implicitly, by the high-level language programmer. The main aim of the abstraction is often to increase programmer productivity but can also be for efficiency or security reasons. Implementing an automatic runtime garbage collector is a common example of an abstraction-level programming task. To date most abstraction-level programming has been done in low-level programming languages such as C. The contents of this thesis describes an investigation into the design of a functional language Nitro, for use in abstraction-level programming. The main goal is to provide the abstraction-level programmer with some of the benefits enjoyed by high-level functional language programmers.
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Johnson, Mary Vaughan. "Space, embodiment and abstraction." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/24102.
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Wang, Xiaoyu 1968. "Variables abstraction in SDL." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33856.
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State explosion problem is an essential impediment in practical applications of formal languages such as SDL, Specification and Description Language. In the context of validation and testing, one of the possible solutions is to abstract a constructed formal specification by removing certain, unimportant from some viewpoint, variables. The resulting system could be more tractable by existing validation and testing tools. In this thesis, we first elaborate methods for abstracting variables in the Extended FSM model and then methods to treat SDL specifications that are based on the EFSM model. The methods are implemented in a tool that is successfully tested on a real life SDL specification.
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Yallop, Jeremy. "Abstraction for web programming." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4683.
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This thesis considers several instances of abstraction that arose in the design and implementation of the web programming language Links. The first concerns user interfaces, specified using HTML forms. We wish to construct forms from existing form fragments without introducing dependencies on the implementation details of those fragments. Surprisingly, many existing web systems do not support this simple scenario. We present a library which captures the essence of form abstraction, and extend it with more practical facilities, such as validation of the HTML a program produces and of the input a user submits. An important part of our library is a simple semantics, given as the composition of three primitive “idioms”, an interface to computation introduced by McBride and Paterson. In order to justify this approach we present a comparison of idioms with the related notions of monads and arrows, refining the informal claims in the literature. Our library forms part of the Links framework for stateless web interactions. We describe a related aspect of this system, a preprocessor that derives generic instances of functions, which we use to serialise server state between client requests. The abstraction in this case involves the shape of datatypes: the serialisation operation is specified independently of the particular types involved. Our final instance of abstraction involves abstract types. Functional programming languages typically offer one of two styles of abstract type: the abstraction boundary may be drawn using a private data constructor, or using a type signature. We show that there is a pair of semantics-preserving translations between these two styles. In the light of this, we revisit the decision of the Haskell designers to offer the constructor style, and define a library that supports signature-style definitions in Haskell by translation into the constructor style.
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Latham, J. T. "Abstraction in program verification." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372026.
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Bezanson, Jeffrey Werner. "Abstraction in technical computing." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99811.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 133-143).
Array-based programming environments are popular for scientific and technical computing. These systems consist of built-in function libraries paired with high-level languages for interaction. Although the libraries perform well, it is widely believed that scripting in these languages is necessarily slow, and that only heroic feats of engineering can at best partially ameliorate this problem. This thesis argues that what is really needed is a more coherent structure for this functionality. To find one, we must ask what technical computing is really about. This thesis suggests that this kind of programming is characterized by an emphasis on operator complexity and code specialization, and that a language can be designed to better fit these requirements. The key idea is to integrate code selection with code specialization, using generic functions and data-flow type inference. Systems like these can suffer from inefficient compilation, or from uncertainty about what to specialize on. We show that sufficiently powerful type-based dispatch addresses these problems. The resulting language, Julia, achieves a Quine-style "explication by elimination" of many of the productive features technical computing users expect.
by Jeffrey Werner Bezanson.
Ph. D.
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Walsh, Toby. "A theory of abstraction." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/20276.
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Abstraction is the process of mapping one representation of a problem onto a simpler, more abstract representation; the abstract solution can then be used to guide the search for a solution to the original, more complex problem. By providing a global control of the search, abstraction can greatly improve our problem solving ability. Unfortunately, the use of abstraction has in general lacked sound and theoretical foundations causing many problems. This thesis therefore proposes a general purpose theory of abstraction. We use this theory to classify the various types of abstraction, to investigate their formal properties, to analyse and criticise previous work in abstraction, to find methods for building abstractions automatically, and to explore how to use abstractions.
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Darabi, Kaveh. "User-centred video abstraction." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/11022.
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The rapid growth of digital video content in recent years has imposed the need for the development of technologies with the capability to produce condensed but semantically rich versions of the input video stream in an effective manner. Consequently, the topic of Video Summarisation is becoming increasingly popular in multimedia community and numerous video abstraction approaches have been proposed accordingly. These recommended techniques can be divided into two major categories of automatic and semi-automatic in accordance with the required level of human intervention in summarisation process. The fully-automated methods mainly adopt the low-level visual, aural and textual features alongside the mathematical and statistical algorithms in furtherance to extract the most significant segments of original video. However, the effectiveness of this type of techniques is restricted by a number of factors such as domain-dependency, computational expenses and the inability to understand the semantics of videos from low-level features. The second category of techniques however, attempts to alleviate the quality of summaries by involving humans in the abstraction process to bridge the semantic gap. Nonetheless, a single user’s subjectivity and other external contributing factors such as distraction will potentially deteriorate the performance of this group of approaches. Accordingly, in this thesis we have focused on the development of three user-centred effective video summarisation techniques that could be applied to different video categories and generate satisfactory results. According to our first proposed approach, a novel mechanism for a user-centred video summarisation has been presented for the scenarios in which multiple actors are employed in the video summarisation process in order to minimise the negative effects of sole user adoption. Based on our recommended algorithm, the video frames were initially scored by a group of video annotators ‘on the fly’. This was followed by averaging these assigned scores in order to generate a singular saliency score for each video frame and, finally, the highest scored video frames alongside the corresponding audio and textual contents were extracted to be included into the final summary. The effectiveness of our approach has been assessed by comparing the video summaries generated based on our approach against the results obtained from three existing automatic summarisation tools that adopt different modalities for abstraction purposes. The experimental results indicated that our proposed method is capable of delivering remarkable outcomes in terms of Overall Satisfaction and Precision with an acceptable Recall rate, indicating the usefulness of involving user input in the video summarisation process. In an attempt to provide a better user experience, we have proposed our personalised video summarisation method with an ability to customise the generated summaries in accordance with the viewers’ preferences. Accordingly, the end-user’s priority levels towards different video scenes were captured and utilised for updating the average scores previously assigned by the video annotators. Finally, our earlier proposed summarisation method was adopted to extract the most significant audio-visual content of the video. Experimental results indicated the capability of this approach to deliver superior outcomes compared with our previously proposed method and the three other automatic summarisation tools. Finally, we have attempted to reduce the required level of audience involvement for personalisation purposes by proposing a new method for producing personalised video summaries. Accordingly, SIFT visual features were adopted to identify the video scenes’ semantic categories. Fusing this retrieved data with pre-built users’ profiles, personalised video abstracts can be created. Experimental results showed the effectiveness of this method in delivering superior outcomes comparing to our previously recommended algorithm and the three other automatic summarisation techniques.
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Fitzgerald, Shane. "Abstraction, Space and Photography." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/391080.
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Much of the published writing about my practice, has focused specifically on the technical approach I employ when constructing the visual image, with very little detailed analysis of the underlying influences, visual language references and historical and contemporary methodologies embedded in the work. This exegesis titled “Abstraction, Space and Photography” identifies some of the fundamental aspects of the abstract visual language I create as a regional artist situated in far north Queensland and attempting to capture its ethos as location and conceptual construct.
Consequently, at the outset I provide some context towards the development of the photographic process that I employ. Although I avoid singular focus on the technical aspects of my image making I am aware that both the technical and conceptual aspects of photography merge in an elemental, and even indexical way, when the artistic intent involves constructing abstract images.
Concept and process are intrinsically linked and cannot be separated, as one informs the other. Anne Marsh describes this relationship:
Unlike conventional photographs Fitzgerald’s large landscapes are constructed without referent in the outside world. Fitzgerald recreates his experience of actual landscapes in these unique works by shining light directly into the camera’s aperture – literally painting with light onto the sensitive surface. The result sits between landscape and abstraction, and challenges assumptions about photography’s identity as a medium.
The series of works developed throughout the Masters (produced 2014-2017) demonstrate an increasing maturity and progression in my practice towards a form of visual language which I would conceive as a kind of photographic abstract expressionism. Heavily influenced by, and in many ways attracted to the more traditional arts — their freedom of expression, additive capacity and representational qualities — this body of work explores photographic images which are imbued with a sense of the painterly and gestural, establishing pluralistic aesthetic connections and strategies of abstraction which stimulate the known — through visualising forms of the unknown.
In contrast to my previous works, these images are visually complex, being characterised by a sense of movement and spatial intrigue. In these works I aim to establish a resolved vernacular that moves beyond the experimental, thereby challenge preconceived notions and expectations for the photograph and going some way towards destabilising the accepted narrative of traditional photography as an indexical medium. The exegesis highlights a number of innovative elements I deploy in creating a contemporary visual language in this body of work which I contend offers unique insights into and perspectives on the environment and landscape of central and far north Queensland and northern Australia. I also present contrasting antecedent pictorial traditions and positivist attitudes which have typified the landscape genre that I evoke.
The following exegesis has been separated into two distinct sections allowing an opportunity to explore my dual interest in abstraction as a device across the mediums of painting and photography and as a vehicle through which to represent spatial subjectivity. Section One: Abstracting Forms explores key texts which I have found most relevant in the development of my practice drawing parallels to the theories and precedents established by critics such as Susan Sontag, Helmut Gernsheim, Aaron Scharf, Lyle Rexer, John Berger, to name a few. Section Two: Representing Space, Time and the Landscape investigates the primary subject which underpins my work discussing the philosophical notions of spatial construction alongside the shifting ideological influences which have underpinned the representation of landscape as it applies in the Australian context.
Throughout the exegesis I have integrated discussion alongside works of key contemporary and historical artists and that of my own to emphasise the resonances between contemporary practice and theory. Artists such as Paul Strand, Man Ray, James Welling, Wolfgang Tillmans, Sigmar Polke, Susan Derges, to name a few, have not only inspired and motivated form and direction within my work but also share similarities in the pursuit of exploration within the medium of photography, seeking to both challenge the preconceived notions of what a photograph is, whilst simultaneously investigating new and progressive developments in the process of image making.Thesis (Masters)
Master of Visual Arts (MVA)
Queensland College of Art
Arts, Education and Law
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Hussey, Stephen W. "The feasibility of sand-abstraction as a viable method of ground water abstraction." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/14054.
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Many rural communities in arid areas of the world make extensive use of perennial water supplies retained within the sediment of a river channel. This naturally filtered water provides for their basic subsistence. A general term applied to the abstraction of water from river sediment is sand-abstraction. Ephemeral and seasonal rivers primarily drain the dryland regions of the world. These arid regions are typically subject to extensive environmental degradation with a consequent high degree of surface erosion. As a result, many of the rivers have become sand rivers, filled with copious amounts of sediment. Most arid areas are subject to occasional rainstorms and flash floods that immediately drain to waterways and saturate the sediment within the river channel. In larger rivers a perennial supply of water is maintained within the sediment. Despite a perceived potential for this water resource there has been little development of any small-scale technology that is suitable for use at a basic rural level. A research and study programme was instigated to assess fully, the potential of such a resource. Field research was undertaken to characterise typical sand rivers and to assess the water storage and water loss and retention factors within river sediment. A check list for identifying possible sand-abstraction sites was devised. In the process of this study the advantages of storing water in sand was fully appreciated and attention given to the development of initially less suitable sites in serious water deficit areas. Systems for efficient abstraction of water were reviewed and designs formulated for the fabrication of equipment to mechanically draw water from river sediment. A series of well-screens, well-points, infiltration galleries and caissons have been designed and initial tests have been conducted under field conditions. Simple technology handpumps that it was considered could be operated, maintained and repaired by rural communities using locally available materials have been developed in conjunction with the abstraction equipment. In consultation with rural people an analysis was made of the technical and sociological requirements that are considered essential for the sustainability of technology suitable for use by disadvantaged rural communities. Both practical and literature research has indicated the latent possibility of this technology. Interaction has been maintained with four communities throughout the research and development period and contributions and indications received are that there is a need to develop such a water source with an upgraded technology. The conclusion from the work undertaken is that development of the technology is worthwhile and that greater efforts should be made to promote it at a small-scale, rural level. In addition the potential to provide clean water in arid regions from such a lowtechnology application should be drawn to the attention of professional water engineers.
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Choueiry, Berthe Y. Choueiry Berthe Yazid. "Abstraction methods for resource allocation /." [S.l.] : [s.n.], 1994. http://library.epfl.ch/theses/?nr=1292.
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Mahmood, Farrukh, and Waqas Rasheed. "Quality Requirement Abstraction Model (QRAM)." Thesis, Blekinge Tekniska Högskola, Institutionen för programvaruteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3397.
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Requirement engineering (RE) is an important phase in any project. Both functional and non-functional requirements are required to be elicited. Quality requirements (QRs) are usually catered at the end of software development process. Along with functional requirements, non-functional (QRs) also need to be handled and implemented through a structural way. It is observed that most organizations do not have proper management for quality requirements in their project life cycles. Especially if we consider the case of market driven requirement engineering (MDRE), it is a dire need to handle those QRs along with the functional requirement using a structural way. In this study we investigate Requirements Abstraction Model (RAM), which is basically designed for MDRE and is the case of continuous RE. The purpose was to analyze RAM specifications, which could be able to provide an effective way of manage QRs. RAM also deals with the specification of QRs, so it was required to investigate that how effective RAM can handle the creation of QRs.
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Zhou, Qingnan. "Abstraction of man-made shapes." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12633.
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Man-made objects are ubiquitous in the real world and in virtual environments. While such objects can be very detailed, capturing every small feature, they are often identified and characterized by a small set of defining curves. Compact, abstracted shape descriptions based on such curves are often visually more appealing than the original models, which can appear to be visually cluttered. We introduce a novel algorithm for abstracting three-dimensional geometric models using characteristic curves or contours as building blocks for the abstraction. Our method robustly handles models with poor connectivity, including the extreme cases of polygon soups, common in models of man-made objects taken from online repositories. In our algorithm, we use a two-step procedure that first approximates the input model using a manifold, closed envelope surface and then extracts from it a hierarchical abstraction curve network along with suitable normal information. The constructed curve networks form a compact, yet powerful, representation for the input shapes, retaining their key shape characteristics while discarding minor details and irregularities.
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Gleeson, Timothy Joseph. "Aspects of abstraction in computing." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334156.
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Greitschus, Marius [Verfasser], and Andreas [Akademischer Betreuer] Podelski. "New techniques for abstraction refinement." Freiburg : Universität, 2018. http://d-nb.info/1174142472/34.
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Ruhrberg, Peter. "Simultaneous abstraction and semantic theories." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/520.
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I present a simple Simultaneous Abstraction Calculus, where the familiar lambda-abstraction over single variables is replaced by abstraction over whole sets of them. Terms are applied to partial assignments of objects to variables. Variants of the system are investigated and compared, with respect to their semantic and proof theoretic properties. The system overcomes the strict ordering requirements of the standard lambda-calculus,and is shown to provide the kind of "non-selective" binding needed for Dynamic Montague Grammar and Discourse Representation Theory. It is closely related to a more complex system, due to Peter Aczel and Rachel Lunon, and can be used for Situation Theory in a similar way. I present versions of these theories within an axiomatic, property-theoretic framework, based on Aczels Frege Structures. The aim of this work is to provide the means for integrating various semantic theories within a formal framework,so that they can share what is common between them, and adopt from each other what is compatible with them.
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Park, Hyoung-June. "Formalization, data abstraction, and communication." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/69376.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1997.Includes bibliographical references (leaves 109-111).
Shape Grammar introduces the algorithm that stimulates the development of form and its meaning in the design process. Since Shape Grammar provides a way of representing form and its meaning as sets of mathematical terms, which are shapes and the different algebra, Shape Grammar has been anticipated for developing an architect's design idea with a computer-aided system. However, its application has been limited in the theoretical analysis of the historical precedents in architecture. Thus, a study of the practical application of Shape Grammar is needed in order to make creative design, in the actual design process, using a CAD system, possible. Through the experimentation with "making follY," this thesis introduces a model for the application of Shape Grammar to the architectural design process. It presents theoretical foundations, describes the methods of formalization, data abstraction, and communication with Shape Grammar in making designs, and illustrates the process of making folly as the result of this thesis. The approach is derived from the study of the different definitions of architectural form and the observation that architects explore formal ideas by producing sequences of drawings, which are schema(s). This thesis investigates possible methods of formalization and data-abstraction based upon schema(s) in the architectural design. Also, this thesis proposes the framework for a prototype computer system that efficiently supports the communication between different computational tools. This communication is established by encoding the design process as the result of the data abstraction, which is composed of shapes as mathematical means, and formalizing the architect's design knowledge according to certain compositional rules. Then, an experiment with "Folly"l design is performed, based upon the suggested methods for the application of Shape Grammar. In conclusion, based upon the results of the experimentation, the initial territory, spatial block, and spatial components in the combination between different algebra are proposed as design methods for the application of Shape Grammar in the making of a creative design. Also, existing problems in the making of practical software are introduced.
by Park, Hyoung-June.
M.S.
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Raad, Azalea. "Abstraction, refinement and concurrent reasoning." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/49218.
Full textAbstract:
This thesis explores the challenges in abstract library specification, library refinement and reasoning about fine-grained concurrent programs. For abstract library specification, this thesis applies structural separation logic (SSL) to formally specify the behaviour of several libraries in an abstract, local and compositional manner. This thesis further generalises the theory of SSL to allow for library specifications that are language-independent. Most notably, we specify a fragment of the Document Object Model (DOM) library. This result is compelling as it significantly improves upon existing DOM formalisms in that the specifications produced are local, compositional and language-independent. Concerning library refinement, this thesis explores two existing approaches to library refinement for separation logic, identifying their advantages and limitations in different settings. This thesis then introduces a hybrid approach to refinement, combining the strengths of both techniques for simple scalable library refinement. These ideas are then adapted to refinement for SSL by presenting a JavaScript implementation of the DOM fragment studied and establishing its correctness with respect to its specification using the hybrid refinement approach. As to concurrent reasoning, this thesis introduces concurrent local subjective logic (CoLoSL) for compositional reasoning about fine-grained concurrent programs. CoLoSL introduces subjective views, where each thread is verified with respect to a customised local view of the state, as well as the general composition and framing of interference relations, allowing for better proof reuse.
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GUIGNET, JEAN-BRUCE. "Abstraction fonctionnelle des composants vlsi." Paris 6, 1998. http://www.theses.fr/1998PA066154.
Full textAbstract:
L'abstraction fonctionnelle des composants vlsi est une methode qui permet de remonter le descriptif comportemental d'un composant vlsi a partir de sa description informatique au niveau masque. La methode qui fait l'objet de cette these met en oeuvre des techniques de reconnaissance de formes. Un langage de description des circuits a reconnaitre a aussi ete specialement elabore a cet effet.
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Parikh, Ankur. "Abstraction Guided Semi-formal Verification." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33596.
Full textAbstract:
Abstraction-guided simulation is a promising semi-formal framework for design validation in which an abstract model of the design is used to guide a logic simulator towards a target property. However, key issues still need to be addressed before this framework can truly deliver on it's promise. Concretizing, or finding a real trace from an abstract trace, remains a hard problem. Abstract traces are often spurious, for which no corresponding real trace exits. This is a direct consequence of the abstraction being an over-approximation of the real design. Further, the way in which the abstract model is constructed is an open-ended problem which has a great impact on the performance of the simulator.
In this work, we propose a novel approaches to address these issues. First, we present a genetic algorithm to select sets of state variables directly from the gate-level net-list of the design, which are highly correlated to the target property. The sets of selected variables are used to build the Partition Navigation Tracks (PNTs). PNTs capture the behavior of expanded portions of the state space as they related to the target property. Moreover, the computation and storage costs of the PNTs is small, making them scale well to large designs.
Our experiments show that we are able to reach many more hard-to-reach states using our proposed techniques, compared to state-of-the-art methods.
Next, we propose a novel abstraction strengthening technique, where the abstract design is constrained to make it more closely resemble the concrete design. Abstraction strengthening greatly reduces the need to refine the abstract model for hard to reach properties. To achieve this, we efficiently identify sequentially unreachable partial sates in the concrete design via intelligent partitioning, resolution and cube enlargement. Then, these partial states are added as constraints in the abstract model. Our experiments show that the cost to compute these constraints is low and the abstract traces obtained from the strengthened abstract model are far easier to concretize.Master of Science
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Mészáros, Flóra. "Hungarian Artists in Abstraction-Creation." Thesis, Paris 4, 2016. http://www.theses.fr/2016PA040088.
Full textAbstract:
Cette thèse se focalise sur le groupe artistique international Abstraction-Création, créé pour servir de forum à l’art non figuratif à Paris entre 1931-1936. Au fil des années, il a eu une centaine de membres, y compris certains artistes hongrois, notamment Étienne Béothy, Alfred Reth, Lajos Tihanyi et Ferenc Martyn, tandis que László Moholy-Nagy était membre sans vivre à Paris. Ce n’est que dans les années 1970 que les premières recherches approfondies ont été menées sur Abstraction-Création. Depuis, l’activité d’Abstraction-Création n’a été que rarement étudiée, sa structure, ses objectifs ou son histoire ont été largement négligés. Le constat est le même pour l’état de la recherche relative à chacun des membres hongrois : jusqu’à présent, seule la participation de Béothy et de Martyn a été analysée en détail. Outre l’objectif principal de cette thèse, notamment la mise en perspective des artistes hongrois dans le groupe, la réévaluation et l’interprétation de l’ensemble de l’activité d’Abstraction-Création sont également mises en lumière. A la base d’une analyse théorique et historique, ce travail compare Abstraction-Création avec deux groupes parisiens non figuratifs. Cette thèse vise à clarifier les différences qui les séparent en soulignant qu’Abstraction-Création ne peut pas être considéré comme une combinaison des deux. Grâce à des documents jusqu’alors non analysés, l'auteur donne un aperçu de la structure organisationnelle de ce forum et discute, à partir d’une perspective entièrement nouvelle, le rôle du comité, leurs débats, leur formation, cessation et leurs plateformes, y compris les réunions, la galerie et le cahier. La thèse démontre la relation entre Abstraction-Création et Surréalisme au moyen d'une analyse stylistique et théorique. Elle prétend que, grâce aux activités des membres hongrois, toutes les facettes du groupe peuvent être présentées. L'auteur révèle quels ont été les objectifs initiaux de l'adhésion des membres hongrois et comment ils ont tiré profit de leur participation. La thèse décrit la période abstraite parisienne des artistes hongrois dans les années 1930, et ce, dans un contexte artistique international et dans un contexte historique plus largeThis dissertation focuses on the international artistic group, called Abstraction-Création (1931-1936. Out of the approximately 100 members joining the association a few were Hungarian artists, namely Étienne Béothy, Alfred Reth, Lajos Tihanyi and Ferenc Martyn, whereas László Moholy-Nagy received an external membership. A deeper research into the Parisian non-figurative formations of the 1930s, including Abstraction-Création, only took shape in the 1970s. Since then, Abstraction-Création has been discussed only occasionally, and a deeper discussion concerning the structure, the goals, or the history of the group is still missing. The same applies to the research on individual Hungarian artists; while for each of them the participation in the forum was presented as an important stage of their lives, so far only the participation of Béothy and Martyn has been examined in detail. Beyond the basic goal of the study to concentrate on Hungarian artists in the group, the re-evaluation and a new examination of Abstraction-Création are also placed in the focus. Based on a theoretical and historical analysis, the study compares Abstraction-Création with two non-figurative Parisian groups, clarifying the differences between them and pointing out that Abstraction-Création could not be viewed as a combination of the two of them. Drawing on hitherto unanalyzed documents, the author gives an overview of the organizational structure of the forum, and discusses, from an entirely new perspective, the role of the committee, their debates, their formation and cessation and their platforms, including their meetings, gallery and journal. The dissertation demonstrates the relation between Abstraction-Création and Surrealism by means of a stylistic and theoretical analysis. It claims that through the activities of the Hungarian members, all the facets of the group can be shown, particularly because of the fact that they did not form a special group within the association, but had their different individual roles and routes. The author presents what the original aims behind the admission of the Hungarian members were and how they benefited from the participation. The dissertation depicts the Parisian abstract period of Hungarian artists in the 1930s in an international artistic context and against a broader historical background
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Kiefer, Stefan. "Abstraction refinement for pushdown systems." [S.l. : s.n.], 2005. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB12103666.
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Lee, Seungjoon. "WISE abstraction framework for wireless networks." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3867.
Full textAbstract:
Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Computer Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Aarts, Fides. "Inference and Abstraction of Communication Protocols." Thesis, Uppsala University, Department of Information Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-111249.
Full textAbstract:
In this master thesis we investigate to infer models of standard communication protocols using automata learning techniques. One obstacle is that automata learning has been developed for machines with relatively small alphabets and a moderate number of states, whereas communication protocols usually have huge (practically infinite) sets of messages and sets of states. We propose to overcome this obstacle by defining an abstraction mapping, which reduces the alphabets and sets of states to finite sets of manageable size. We use an existing implementation of the L* algorithm for automata learning to generate abstract finite-state models, which are then reduced in size and converted to concrete models of the tested communication protocol by reversing the abstraction mapping.
We have applied our abstraction technique by connecting the Learn-Lib library for regular inference with the protocol simulator ns-2, which provides implementations of standard protocols. By using additional reductionsteps, we succeeded in generating readable and understandable models of the SIP protocol.
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Zhao, Shu Jie. "Line drawings abstraction from 3D models." Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b2130124.
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Polyvyanyy, Artem, Sergey Smirnov, and Mathias Weske. "The triconnected abstraction of process models." Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2009/3284/.
Full textAbstract:
Contents:
Artem Polyvanny, Sergey Smirnow, and Mathias Weske
The Triconnected Abstraction of Process Models
1 Introduction
2 Business Process Model Abstraction
3 Preliminaries
4 Triconnected Decomposition
4.1 Basic Approach for Process Component Discovery
4.2 SPQR-Tree Decomposition
4.3 SPQR-Tree Fragments in the Context of Process Models
5 Triconnected Abstraction
5.1 Abstraction Rules
5.2 Abstraction Algorithm
6 Related Work and Conclusions
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Kleine, Matthias, Robert Hirschfeld, and Gilad Bracha. "An abstraction for version control systems." Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/5562/.
Full textAbstract:
Versionsverwaltungssysteme (VCS) ermöglichen es Entwicklern, Änderungen an Softwareartifakten zu verwalten. VCS werden mit Hilfe einer Vielzahl verschiedener Werkzeuge bedient, wie z.,B. graphische Front-ends oder Kommandozeilenwerkzeuge. Es ist wünschenswert mit einzelnen solcher Werkzeuge unterschiedliche VCS bedienen zu können.
Bislang hat sich jedoch keine Abstraktion für Versionsverwaltungssysteme durchgesetzt, mit deren Hilfe solche Werkzeuge erstellt werden können. Stattdessen implementieren Werkzeuge zur Interaktion mit mehreren VCS ad-hoc Lösungen.
Diese Masterarbeit stellt Pur vor, eine Abstraktion über Versionsverwaltungskonzepte. Mit Hilfe von Pur können Anwendungsprogramme entwickelt werden, die mit mehreren Versionsverwaltungssystemen interagieren können. Im Rahmen dieser Arbeit wird eine Implementierung dieser Abstraktion bereitgestellt und mit Hilfe eines Anwendungsprogramms validiert.Version Control Systems (VCS) allow developers to manage changes to software artifacts. Developers interact with VCSs through a variety of client programs, such as graphical front-ends or command line tools. It is desirable to use the same version control client program against different VCSs. Unfortunately, no established abstraction over VCS concepts exists. Instead, VCS client programs implement ad-hoc solutions to support interaction with multiple VCSs. This thesis presents Pur, an abstraction over version control concepts that allows building rich client programs that can interact with multiple VCSs. We provide an implementation of this abstraction and validate it by implementing a client application.
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Streader, David. "Abstraction and refinement of process actions." Thesis, Queen Mary, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368046.
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Chorfi, Redha. "Abstraction et vérification de programmes informatiques." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25710/25710.pdf.
Full textAbstract:
Les systèmes informatiques offrent une grande flexibilité aux usagers en leur permettant
l’accès, notamment par le biais de réseaux de télécommunication ou de l’Internet, à
un vaste éventail de services. Toutefois, certains de ces services sont soumis à de fortes
contraintes de sécurité, comme le télépaiement qui est au coeur du commerce électronique.
Ainsi, les fournisseurs et les utilisateurs expriment des besoins croissants, et antagonistes,
en sécurité. Répondre à ces deux besoins simultanément est un enjeu technologique transversal
à de nombreux domaines de l’informatique. L’objectif de ce travail est de développer
un mécanisme permettant de garantir la sécurité des systèmes, en s’appuyant sur
l’expérience établie dans le domaine de la sécurité et des méthodes formelles. Pour se
faire, nous définissons un nouveau cadre de vérification des propriétés de sécurité d’un
programme informatique par l’analyse des flots de données et de contrôle construits à
partir du code de ce dernier. L’idée principale consiste à définir un modèle pouvant abstraire
la trace d’événements et les dépendances de ressources engendrés au moment de
l’exécution du programme, et pouvant être soumis à des algorithmes de vérification de
modèle (model-checking) pour l’analyse de la sûreté du programme vis-à-vis d’une propriété.
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Parry, Aneurin Stefan. "Limits of abstraction in electroacoustic music." Thesis, City University London, 2000. http://openaccess.city.ac.uk/1129/.
Full textAbstract:
In this thesis the relationship between abstract and representational aspects of electroacoustic music will be discussed. Such an exploration exposes the limits of abstraction in electroacoustic music, as the interaction between musical form and the world outside the immanent context of the work is revealed. In Chapter 1 an examination of the complex system of relationships between sounds within a musical structure and the representational nature of many of the sounds themselves, referring to their origins in the real world, suggests analogies with poetic texts and early twentieth century painting. In Chapter 2 there follows a discussion of ideas contained in Simon Emmerson’s article The Relation of Language to Materials (Emmerson, 1985). Emmerson’s ideas are examined and expanded, with particular regard to the relationship of syntax and discourse. In Chapter 3 the compositional methodology of sound manipulation is discussed, contrasting analytical and synthetic approaches to sound transformation and Ten Hoopen’s model of the specific / surrogate continuum (Ten Hoopen 1994) is discussed and developed. An analogy between structures based on dissonance / resolution and ambiguous / specific source recognition is developed with particular reference to the work Grand Junction. In Chapter 4 a new model, the associative field model, is proposed to examine more closely the nature of ambiguous source recognition with particular reference to the cycle of Seasons. The rôle of ambiguity in aesthetic appreciation is discussed. Finally, in Chapter 5, the interaction of the work with its wider context is discussed. The influence of literary accompaniments to the work, such as the title and programme note is considered as is collaboration in the form of music specifically created for contemporary dance, as exemplified in The Killing Floor. The interaction of the work and the performance space is considered in the site-specific installations Boomtown and Living Steam.
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Liu, Xiaodong. "Abstraction : a notion for reverse engineering." Thesis, De Montfort University, 1999. http://hdl.handle.net/2086/4214.
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Boyle, Joseph. "Abstraction and the judgement of taste." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334496.
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Iglesias, Pablo Nogueira. "Polytypic functional programming and data abstraction." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430769.
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Kalofonos, Dionysis. "Simplifying graph-based planning through abstraction." Thesis, University of Aberdeen, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446082.
Full textAbstract:
The main focus of the dissertation is on the method of integration of causal and resource reasoning that can expedite problem solving by graphbased planners. We present a representation of the lifted planned graph constructed by the MADPlan planner, which is populated with exclusivity relations and binary constraints. Moreover, the lifted nodes that appear within the graph maintain references to classes of resources which constitute the domain of the uninstantiated variables appearing in the lifted nodes. The exclusivity relations, binary constraints, and resource references are used to guide the search towards the extraction of executable plans. We discuss the search method used in MADPlan that achieves the extraction of grounded plans directly from lifted planning graphs. The main characteristic of the search is that it can switch between two different backtracking methods. During chronological backtracking the algorithm tries a new resource allocation for a given node only when the node appears in the conflict set. Otherwise the algorithm immediately backtracks further (backjumps) ignoring the remaining resource allocations for the last visited node. The contributions discussed above allow our planner to scale very well with the increasing number of resources that appear in planning. The above contributions are direct extensions to the graphbased planning paradigm and they can be utilised by all graphbased planners.
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Menaa, Mohamed Nabih. "On the compositionality of round abstraction." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3381/.
Full textAbstract:
Game Semantics is an approach to denotational semantics that has been successful in providing accurate, fully abstract models for various programming languages. It has thereafter been applied, amongst other things, to model checking, access control analysis, information flow analysis, and recently, hardware synthesis. While the roots of modern Game Semantics are sequential, several game models of asynchronous concurrency have since been devised. However, synchronous concurrency has not been considered hitherto. This thesis studies synchronous concurrency in game-like models. The central idea is to investigate deriving such synchronous models from their asynchronous counterparts using round abstraction--a technique that allows aggregating a sequence of computational steps to form a larger, more abstract macro-step. We define round abstraction within a trace-semantic setting that generalises game semantic models. We note that, in general, round abstraction is not compositional. We then identify sufficient conditions to guarantee correct composition, thereby proposing a framework for round abstraction that is sound when applied to synchronous and asynchronous behaviours. We explore extensions of our synchronous model with causality, global clocks and determinism.
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Rodrigues, Rodrigo Seromenho Miragaia 1975. "Combining abstraction with Byzantine fault-tolerance." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86764.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 83-86).
by Rodrigo Seromenho Miragaia Rodrigues.
S.M.
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Cockton, Gilbert. "Architecture and abstraction in interactive systems." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1460.
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Farquharson, Roy G. "Fetal abstraction of placental steroid hormones." Thesis, University of Aberdeen, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328653.
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Baier, Thomas, Jan Mendling, and Mathias Weske. "Bridging abstraction layers in process mining." Elsevier, 2014. http://dx.doi.org/10.1016/j.is.2014.04.004.
Full textAbstract:
While the maturity of process mining algorithms increases and more process
mining tools enter the market, process mining projects still face the
problem of different levels of abstraction when comparing events with modeled
business activities. Current approaches for event log abstraction try to
abstract from the events in an automated way that does not capture the
required domain knowledge to fit business activities. This can lead to misinterpretation
of discovered process models. We developed an approach that
aims to abstract an event log to the same abstraction level that is needed
by the business. We use domain knowledge extracted from existing process
documentation to semi-automatically match events and activities. Our abstraction
approach is able to deal with n:m relations between events and
activities and also supports concurrency. We evaluated our approach in two
case studies with a German IT outsourcing company.
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Laurentin, Marc. "Abstraction fonctionnelle des circuits integres cmos." Paris 6, 1994. http://www.theses.fr/1994PA066620.
Full textAbstract:
Dans ce memoire est presentee une methode permettant l'abstraction d'equations logiques de circuits integres cmos. L'approche proposee se base sur l'abstraction prealable d'un reseau de portes orientees a partir de la description du circuit au niveau transistor. Ce type de description, dont ne disposent pas toujours les concepteurs (generateurs, full-custom etc. ), peut etre utilisee par des verificateurs temporels ou fonctionnels rapides. Certains outils de test s'appuient aussi sur ce type de description. La modelisation du circuit en sous-reseaux etant presentee, l'etude realisee ici porte sur les conditions de conduction des chemins electriques qui composent ces sous-reseaux. La prise en compte de leur environnement (contraintes sur les entrees) passe par la detection et l'exploitation des correlations logiques entre les signaux du circuit. La description comportementale des sous-reseaux, est derivee des chemins electriques. La methode proposee s'appuie essentiellement sur les informations logiques qu'il est possible de deriver de la structure du circuit. En particulier, elle ne s'appuie pas sur une bibliotheque de formes pre-definies et ne requiert pas d'information de la part du concepteur du circuit. Elle peut donc etre appliquee a des circuits, dont la structure interne n'est pas connue. Les algorithmes implementant cette methode sont decrits, ainsi que les resultats obtenus sur des circuits de provenance universitaire, et industrielle
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Wadoo, Sabiha Amin. "Evacuation Distributed Feedback Control and Abstraction." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27439.
Full textAbstract:
In this dissertation, we develop feedback control strategies that can be used for evacuating people. Pedestrian models are based on macroscopic or microscopic behavior. We use the macroscopic modeling approach, where pedestrians are treated in an aggregate way and detailed interactions are overlooked. The models representing evacuation dynamics are based on the laws of conservation of mass and momentum and are described by nonlinear hyperbolic partial differential equations. As such the system is distributed in nature.
We address the design of feedback control for these models in a distributed setting where the problem of control and stability is formulated directly in the framework of partial differential equations. The control goal is to design feedback controllers to control the movement of people during evacuation and avoid jams and shocks. We design the feedback controllers for both diffusion and advection where the density of people diffuses as well as moves in a specified direction with time. In order to achieve this goal we are assuming that the control variables have no bounds. However, it is practically impossible to have unbounded controls so we modify the controllers in order to take the effect of control saturation into account. We also discuss the feedback control for these models in presence of uncertainties where the goal is to design controllers to minimize the effect of uncertainties on the movement of people during evacuation. The control design technique adopted in all these cases is feedback linearization which includes backstepping for higher order two-equation models, Lyapunov redesign for uncertain models and robust backstepping for two-equation uncertain models.
The work also focuses on abstraction of evacuation system which focuses on obtaining models with lesser number of partial differential equations than the original one. The feedback control design of a higher level two-equation model is more difficult than the lower order one-equation model. Therefore, it is desirable to perform control design for a simpler abstracted model and then transform control design back to the original model.Ph. D.
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Khan, Jehandad. "Holistic Abstraction for Distributed Network Debugging." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/93500.
Full textAbstract:
Computer networks are engineered for performance and flexibility, delivering billions of packets per second with high reliability, until they fail. It is during such time of crisis that debugging and troubleshooting come to the forefront, however, the focus on performance results in design tradeoffs that make it challenging to troubleshoot them. This dissertation hypothesizes that a view of the network as a single entity solves the above problems, without compromising either performance or visibility. The primary contributions are 1) a topology oblivious network abstraction for performance monitoring and troubleshooting, 2) transformation of the network abstract query to device local semantics, 3) optimizations for reducing state collection overhead, and 4) global state semantics in the proposed query language easing expression of network queries. Abstracting the entire system as an entity simplifies the debugging process, making possible comprehensive root-cause analysis and exonerating the network administrator from dealing with many devices, delivering gains in productivity and efficiency. By merging network topology information with state collection, this thesis provides a new way to look at the network monitoring and troubleshooting problem. Such an amalgamation allows the translation of a performance query expressed in a domain specific language to small pieces of code operating on different devices in the network collecting necessary state. This merging results in lesser overhead per switch and reduces the strain on devices and provides a simple abstraction to the administrator.PHD