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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Safety through security

Simpson, Andrew C. January 1996 (has links)
In this thesis, we investigate the applicability of the process algebraic formal method Communicating Sequential Processes (CSP) [Hoa85] to the development and analysis of safetycritical systems. We also investigate how these tasks might be aided by mechanical verification, which is provided in the form of the proof tool Failures-Divergences Refinement (FDR) [Ros94]. Initially, we build upon the work of [RWW94, Ros95], in which CSP treatments of the security property of non-interference are described. We use one such formulation to define a property called protection, which unifies our views of safety and security. As well as applying protection to the analysis of safety-critical systems, we develop a proof system for this property, which in conjunction with the opportunity for automated analysis provided by FDR, enables us to apply the approach to problems of a sizable complexity. We then describe how FDR can be applied to the analysis of mutual exclusion, which is a specific form of non-interference. We investigate a number of well-known solutions to the problem, and illustrate how such mutual exclusion algorithms can be interpreted as CSP processes and verified with FDR. Furthermore, we develop a means of verifying the faulttolerance of such algorithms in terms of protection. In turn, mutual exclusion is used to describe safety properties of geographic data associated with Solid State Interlocking (SSI) railway signalling systems. We show how FDR can be used to describe these properties and model interlocking databases. The CSP approach to compositionality allows us to decompose such models, thus reducing the complexity of analysing safety invariants of SSI geographic data. As such, we describe how the mechanical verification of Solid State Interlocking geographic data, which was previously considered to be an intractable problem for the current generation of mechanical verification tools, is computationally feasible using FDR. Thus, the goals of this thesis are twofold. The first goal is to establish a formal encapsulation of a theory of safety-critical systems based upon the relationship which exists between safety and security. The second goal is to establish that CSP, together with FDR, can be applied to the modelling of Solid State Interlocking geographic databases. Furthermore, we shall attempt to demonstrate that such modelling can scale up to large-scale systems.
12

An investigation into the application of block processing techniques for the Global Positioning System

Uijt de Haag, Maarten. January 1999 (has links)
Thesis (Ph. D.)--Ohio University, August, 1999. / Title from PDF t.p.
13

Analyzing binary longitudinal data in adaptive clinical trials /

Bari, Wasimul, January 2003 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 2003. / Bibliography: leaves 109-112. Also available online.
14

Design and implementation of a library to support the Common Component Architecture (CCA) over Legion

Bari, Himanshu. January 2004 (has links)
Thesis (M.S.)--State University of New York at Binghamton, Department of Computer Science, 2004. / Includes bibliographical references.
15

Identifying and exploiting symmetry for CSP refinement checking

Moffat, Nicholas January 2011 (has links)
No description available.
16

Protocol sequences for the collision channel without feedback. / CUHK electronic theses & dissertations collection

January 2010 (has links)
At last, we focus on the detection problem in the protocol sequence design. The objective is to construct user-detectable sequences that allow any active user be detected by the receiver via some algorithm within some bounded delay if and only if it has become active. / First of all, in order to minimize variation of throughput due to delay offsets, we investigate protocol sequences whose pairwise Hamming cross-correlation is a constant for all possible relative offsets. It can be viewed as a generalization of completely shift-invariant sequences, which can achieve the zero-variation in throughput over a slot-synchronized channel. / Provided that the number of active users is smaller than the number of potential users, strongly conflict-avoiding codes are introduced with the non-blocking property in the asynchronous channel. It can be viewed as an extension of completely irrepressible sequences. / The second one is a non-blocking property which ensures that each active user can successfully transmit information at least once in its each active period. With the assumption that all potential users may be active simultaneously, user-irrepressible sequences and completely irrepressible sequences are studied respectively for different level of synchronization, to support the non-blocking property. / This thesis is based on Massey's model on collision channels without feedback, in which collided packets are considered unrecoverable. A collision occurs if two or more packets are partially or totally overlapped. Each potential user is assigned a deterministic zero-one pattern, called the protocol sequence, and sends a packet if and only if it is active and the value of the sequence is equal to one. Due to lack of feedback, the beginning of the protocol sequences cannot be synchronized and variation in relative offsets is inevitable. It further yields variation in throughput. / We study the design of protocol sequences from three different perspectives. / Zhang, Yijin. / Adviser: Wing Shing Wong. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 1116). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
17

Design and implementation of pulse sequences for application in MRI /

Jang, Geon-Ho, January 1999 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 118-123). Also available on the Internet.
18

Design and implementation of pulse sequences for application in MRI

Jang, Geon-Ho, January 1999 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 118-123). Also available on the Internet.
19

Approximation algorithms for covering problems

Koufogiannakis, Christos. January 2009 (has links)
Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Title from first page of PDF file (viewed March 11, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 70-77). Also issued in print.
20

A mathematical theory of communicating processes

Roscoe, Andrew William January 1982 (has links)
(Brief abstract written by the author in 2011 since I don't have the original to hand.) This thesis introduced much of the theory for Hoare's CSP, including the failures and failures-divergences model and methods of proving properties of processes based on metric, order and topological structures. The final chapter investigates the structures underlying operational semantics.

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