<p>Lack of generality in deployment of Wireless Sensor Networks gives rise to many application specific research questions. In order to maintain safe levels of radiation, a Sensor Network can be used to provide greater flexibility within the McMaster Nuclear Reactor (MNR). Sensor Networks have conventionally been deployed in natural habitat areas, and to our knowledge, this is the first attempt to model its behavior inside a research reactor. This application specific scenario provides insight in derermining the suitability of embedding Sensor Networks in nuclear reactors. Traditional networks have been designed to accommodate various applications. In this case, we believe that sensor networks, which serve a specific task, can be customized depending on the application. By tailoring a Sensor Network for the Nuclear Reactor, one will be able to maximize efficiency.</p> <p>This thesis states a set of requirements for deploying a Sensor Network in the MNR. By using these requirements, the challenges surrounding Sensor Network communications were studied. These results are to provide McMaster's Health Physics department with the proper guidance if choosing to deploy such a network. The research defines the optimal MAC, and Sensor Network routing protocols for the reactor. The metrics used to determine optimality are reliability, latency, scalability, and lifetime. The approach to determine the suitability of sensor networks in the MNR is a discrete-event simulator called J-Sim. J-Sim is extended to simulate the various protocols that were studied in this research including One-Hop, Multi-Hop, LEACH, TDMA, and CSMA. Results indicate that a modified version of LEACH, called MNRLEACH, best suits the needs of the McMaster Nuclear Reactor.</p> / Master of Science (MSc)

<p>Sensitivity of clinical data and strict rules regarding data sharing have caused privacy and security to be critical requirements for using patient profiles in distributed healthcare environments. The amalgamation of new information technology with traditional healthcare workflows for sharing patient profiles has made the whole system vulnerable to privacy and security breaches. Standardization organizations are developing specifications to satisfy the required privacy and security requirements. In this thesis we present a novel access control model based on a framework designed for data and service interoperability in the healthcare domain. The proposed model for customizable access control captures the dynamic behavior of the user and determines access rights accordingly. The model is generic and flexible in the sense that an access control engine dynamically receives security effective factors from the subject user, and identifies the privilege level in accessing data using different specialized components within the engine. Standard data representation formats and ontologies are used to make the model compatible with different healthcare environments. The access control engine employs an approach to follow the user's behavior and navigates between engine components to provide the user 's privilege to access a resource. A simulation environment is implemented to evaluate and test the proposed model.</p> / Master of Science (MSc)

<p>Pixel values in MR images are linear combinations of contributions from multiple tissue fractions. The tissue fractions can be recovered using the Moore-Penrose pseudo-inverse if the tissue parameters are known, or can be deduced using machine learning. Acquiring sufficiently many source images may be too time consuming for some applications. In this thesis, we show how tissue fractions can be recovered from partial k-space data, collected in a fraction of the time required for a full set of experiments. The key to reaching significant sample reductions is the use of regularization. As an additional benefit, regularizing the inverse problem for tissue fractions also reduces the sensitivity to measurement noise. Numerical simulations are presented showing the effectiveness of the method, showing three tissue types. Clinically, this corresponds to liver imaging, in which normal liver, fatty liver and blood would need to be included in a model, in order to get an accurate fatty liver ratio, because all three overlap in liver pixels (via partial voluming).</p> / Master of Science (MSc)

<p>The problem of computing winning strategies in games has yielded many important results with applications in fields such as computer science, economics, and mathematics. For example, "Online" games, where the input is received on the fly are used to model process scheduling and paging algorithms. The concept of Nash Equilibrium has implications in economic theory, and Ehrenfeuct-Frass games are used to check whether two structures are isomorphic.</p> <p>In this thesis we are concerned with Partially-Ordered Set (Poset) games. We present two new methods for proving that computing winning strategies for the game of Chomp is in PSPACE. \Ne also present the idea of "Game Completeness", and give an overview of efforts to translate any poset game into an equivalent configuration of Chomp. Finally, we show how Skelley's bounded arithmetic theory W¹₁ can be applied to Chomp, and the consequences of expressing the existence of a winning strategy for the first player in Chomp in simpler arithmetic theories. In short, the contributions of this thesis are as follows:</p> <p>1. A new method for showing poset games in PSPACE, via a polynomial-time (logarithmic-space) reduction to the game of Geography.</p> <p>2. Attempts at a reduction from Geography to poset games, and implications to whether poset games are PSPACE-complete.</p> <p>3. A bounded-arithmetic formulation of the existence of a winning strategy for the first player in Chomp.</p> <p>4. A definition of the concept of Game Completeness, and a translation from treelike poset games to a modified version of Chomp.</p> / Master of Applied Science (MASc)

We extend the original selfish routing setting by introducing users who are oblivious to congestion. Selfish routing captures only the behavior of selfish users, who choose the cheapest route based on the current traffic congestion without caring about the effects of their routing on their fellow users. However, it is more likely that a certain number of network users will be oblivious to congestion. For example, data from low-level QoS services will be routed on predefined routes with no adaptability to network congestion, while data from high-level QoS services will be routed on the fastest paths available. Networks with selfish users may lead to a stable state or Nash equilibrium, where no selfish users can decrease his or her travel time by changing his or her route unilaterally. Traffic equilibria refer to Nash equilibria in networks only with selfish users, and oblivious equilibria refer to Nash equilibria in networks with both oblivious users and selfish users. We study the performance degradation of networks at oblivious equilibrium with respect to the optimal performance. Our model has a fraction a of oblivious users, who choose predefined shortest paths on the network, and the remaining are selfish users. Considering networks with linear latency functions, first we study parallel links networks with two nodes, and then general topologies. We provide two tight upper bounds of the price of anarchy, which is the ratio of the worst total cost experienced by both oblivious users and selfish users, over the optimal total cost when all users are centrally coordinated. Our bounds depend on network parameters such as a, the total demand, the latency functions, the total cost of a traffic equilibrium flow, and the total cost of an optimal flow. The dependency of our bounds on network parameters seems to be inevitable considering the fact that the price of anarchy can be arbitrary large depending on network parameters as oblivious users may choose an arbitrarily expensive path. / Master of Science (MSc)

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Nov. 25, 2008). PDF text: xiii, 173 p. : ill. ; 2 Mb. UMI publication number: AAT 3315261. Includes bibliographical references. Also available in microfilm and microfiche formats.

<p>Healthcare System Integration is an area of utmost importance in the overall eHealth<br />strategy of Ontarios provincial government as well as the federal government of Canada. A large body of researchers from various governmental and non-governmental<br />organizations are actively engaged in delivering solutions to integrate disparate healthcare information systems. The overall goal of these efforts is to provide a provincewide and nation-wide unified view of clinical information to healthcare practitioners, thereby enabling them to deliver accurate and timely services to the general public in a cost-efficient manner.<br />While the need for health information integration is clear, due to inherent complexities<br />of the healthcare domain as well as health information standards such as Health Level 7 (HL7), completion of such projects within budget and time is not an easy task. The goal of this study is to understand and analyze the information architecture behind HL7 version 3 (HL7 v3) with the aim of simplifying healthcare system integration process. In this thesis, we present a novel framework for extracting HL7 v3 messages to represent healthcare transactions that take place in an integration scenario. We have developed a prototype tool based on semantic web (SW) technologies to support our approach. We also present three healthcare case studies to demonstrate our solution.</p> / Master of Applied Science (MASc)

<p>In this thesis we provide a Linear Programming (LP) formulation and a heuristic for the symmetric Traveling Salesman Problem (TSP) on certain complete graphs having the triangle inequality.</p> <p>TSP models cities and their pairwise connections as vertices and edges between them in a graph. The distances are represented by cost values on edges, and the goal is to find a minimum weight tour that visits every vertex exactly once. In symmetric cases all connections are undirected - both directions have the same cost. This problem is NP-Complete, so there is no polynomial time exact algorithm known for it.</p> <p>We present three major points in this thesis. Inspired by an LP formulation of perfect matching, we develop a relaxation for TSP, and prove that our relaxation is equivalent to the path form of the well-known Held-Karp formulation. Then, based on this relaxation we construct a heuristic, hoping it can approach a constant factor 4/3 of the optimal objective value given by the LP relaxation. At last, we adopt the matroid idea. It's already known that TSP can be modeled as minimum weight intersection of three matroids, but solving that is also NP-Complete. Vle present in this thesis the attempt to approach it using only two matroids, and analyze the difficulty.</p> / Master of Science (MS)

<p>Molecular imaging is an exciting and relatively new technology that has found widespread use in the diagnosis and observation of various diseases. More recently, molecular imaging has penetrated areas such as drug development in order to facilitate the observation and analysis of the effects of newly developed drugs. The amounts of data in drug development experiments may be very large due to the fact that they contain both spatial and temporal information of medical images. Imaging techniques can facilitate the analysis of large amounts of data by automating information extraction and providing meaningful results.</p> <p>The focus of the project concerning this thesis is to create a emporal and spatial atlas of an animal by utilizing and integrating data from images of different modalities. More specifically, the application treated in the thesis makes use of ventilation and perfusion data from CT and SPECT scans in order to aid in the observation of the effects of newly developed drugs in the treatment of lung diseases. This thesis describes the segmentation and registration techniques used in detail and how these were utilized to align and combine ventilation and perfusion data from both CT and SPECT scans.</p> / Master of Applied Science (MASc)

<p>In industry many legacy systems exist which run mission or safety critical code which do not have adequate requirements documentation. This thesis demonstrates how the use of a functional programming language eases a flexible and modular approach to the construction of libraries and tool suites that allow the manipulation of assembly language programs. The tools and libraries created with this method are used in a larger project of reverse engineering requirements from legacy assembly programs.</p> <p>The modules presented operate from the assembled ".lst" format, which is the result of assembling the source files, and includes the calculated address in memory and the binary version of the given instructions. Our libraries provide representations of assembly programs in an abstract data type and as internal graph representations, and conversions to a GXL graph format and to other special-purpose XML representations.</p> <p>The use of Haskell as an implementation language is explored in the context of a software engineering project, and some of the benefits and disadvantages of such a choice are discussed. This work was funded by Ontario Power Generation and CITO (Communications and Information Technology Ontario).</p> / Master of Science (MSc)