Department: Computer Science and Systems Analysis ![[clear]](close-x.png "Remove this limiter")
44 matches in the database.
These are records: 1 - 30.
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1.
Arockiasamy, Savarimuthu.
Using the SKOS Model for Standardizing Semantic Similarity and Relatedness Measures for Ontological Terminologies.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2009, Miami University
► Semantic similarity and relatedness measures assess how alike two words are within…
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▼ Semantic similarity and relatedness measures assess how alike two words are within a language and are playing an important role in the development of the Semantic Web. This thesis research advances the knowledge of existing similarity and relatedness measures. A generalized tool to experiment with semantic similarity and relatedness measures in a variety of ontological terminologies has been developed using the Simple Knowledge Organization System (SKOS), a proposed W3C standard for the Semantic Web. SKOS represents a terminology or domain vocabulary in a machine-understandable way. A flexible conversion tool is used to convert any vocabulary in the Unified Medical Language System (UMLS) Metathesaurus and OWL ontologies into an extended SKOS ontological terminology. The generalized tool for measuring semantic similarity and relatedness is then used to analyze a wide variety of semantic similarity measures and new set-based relatedness measures on three major vocabularies of the UMLS Metathesaurus.
Advisors/Committee Members: Cross, Valerie.
Subjects: Computer science
Keywords: Semantic similarity; Semantic relatedness; UMLS2SKOS
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2.
Bathija, Vishal.
An Adaptation Methodology for Reusing Ontologies.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2006, Miami University
► Ontologies are an emerging means of knowledge representation that can improve information…
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▼ Ontologies are an emerging means of knowledge representation that can improve information organization and management in an application. They have demonstrated their value in numerous application areas such as intelligent information integration or information brokering since they offer the technical support for sharing and exchanging information between human and/or software agents. Despite their successes, their time-consuming and expensive development process deters the prevalent use of ontologies. Thus, research is focusing on ways to improve the process of ontology construction which involves recognizing, representing, and recording concept definitions and their relationships. This thesis research investigates existing methods for ontology learning and develops ontology adaptation software architecture for transforming an ontology from one domain to a related or similar domain. Using this software, the SEURAT’s Argument Ontology for the domain of software engineering is adapted to create an initial ontology that supports engineering design for the specific problem domain of spacecraft design.
Advisors/Committee Members: Cross, Valerie V.
Keywords: Ontologies; ontology learning; design rationale; engineering design; ontology pruning; ontology merging
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3.
Busch, Rebecca Lynn.
Language Design for Token Server Authentication Policies.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2004, Miami University
► There exist computer networks in which multiple services forward the credentials of…
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▼ There exist computer networks in which multiple services forward the credentials of their users to a central server for authentication. Though the communication lines between the services and the central server may be encrypted, each service has plaintext access to the username/password pairs and can easily store copies. A solution to this security problem is the use of a temporary token in place of the password. Substituting short-lived tokens for the real passwords solves the problem of compromised passwords since only the token may be stolen; however, the tokens may become compromised as well. For this reason, restrictions must be placed on the creation and validation of tokens to reduce the likelihood of their compromise. In this work, I present an authentication policy language developed to express the rules necessary to govern the token creation and validation processes.
Advisors/Committee Members: Campbell, Scott T.
Subjects: Computer Science
Keywords: authentication policy; language
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4.
Campbell, Sherrie L.
ADEPT: A Tool to Support the Formal Analysis of Software Design.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2009, Miami University
► Formal specification languages can be used to support the rigorous development of…
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▼ Formal specification languages can be used to support the rigorous development of complex software systems when these systems must be of high quality. Unfortunately, writing formal specifications and refining them into designs can be a challenging activity. Use of design patterns, which are a widely accepted design activity, helps create quality designs, but adds further complexity to the design activity.We have developed a tool ADEPT, Advanced Design Employing Pattern Templates, that aids designers in using both formal specifications and design patterns. The software developer will use the ADEPT tool to guide them through the process of choosing a design pattern that is related to their formal system specification for the purpose of automatically supporting refinement. The user is guided through refining the specification and creating a design that not only incorporates one of the design patterns but also meets the given system specification.
Advisors/Committee Members: Sobel, Ann.
Subjects: Computer science
Keywords: Software Design; Formal Methods; Design Methodology; Design Patterns; Formal Specifications
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5.
Dai, Yan.
A NEW IMPLEMENTATION OF CLUSTERING ALGORITHM AND ITS APPLICATION IN NET-TREE CONSTRUCTION ALGORITHM.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2009, Miami University
► In a vertex k-center problem, the goal is to pick some vertexes,…
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▼ In a vertex k-center problem, the goal is to pick some vertexes, called centers, from a given undirected weighted graph so as to minimize the maximum distance of any vertex from its closest center. It is known that not only is k-center an NP-complete problem, but approximating the k-center problem within a factor better than 2 is still NP-complete [2]. If the distance between any two vertices is given as a distance matrix (so distance computations take constant time), the 2-approximation k-center problem can be solved in O(n•logk) time [2]. But to build such a distance matrix for a large-size road map is impractical because even storing the distance matrix is impractical, because it requires n2 space. In this paper, I propose a new algorithm that gives a 2-approximation to the vertex k-center problem in O(λ2•n•logn•logφ) time in road maps, where λ is the doubling constant and φ is the spread of the graph, without being given the distance matrix in advance.
Advisors/Committee Members: Brinkman, Bo.
Subjects: Computer science
Keywords: clustering; k-center; net-tree; geometric algorithm; doubling dimension; doubling constant
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6.
Dempsey, Tae.
Intelligent Sensing and Classification in DSR-Based Ad Hoc Networks.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2009, Miami University
► Wireless ad hoc networks have fundamentally altered today's battlefield, with applications ranging…
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▼ Wireless ad hoc networks have fundamentally altered today's battlefield, with applications ranging from unmanned air vehicles to randomly deployed sensor networks. Security and vulnerabilities in wireless ad hoc networks have been considered at different layers, and many attack strategies have been proposed, including denial of service (DoS) through the intelligent jamming of the most critical packet types of flows in a network. This thesis investigates the effectiveness of intelligent jamming in wireless ad hoc networks using the Dynamic Source Routing (DSR) and TCP protocols and introduces an intelligent classifier to facilitate such jamming. Assuming complete packet encryption, we develop probabilistic classification algorithms that improve upon previous schemes. These algorithms can then facilitate intelligent packet jamming and are based solely on the observable characteristics of size, inter-arrival timing, and direction. We model size and time as probability distributions and use direction as a supporting metric to produce a 99.4% accurate classifier.
Advisors/Committee Members: Sahin, Gokhan.
Subjects: Computer science; Engineering
Keywords: ad hoc, dsr, classification, algorithms, jamming
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7.
Doshi, Rajesh J.
SIMULTANEOUS ROBOT LOCALIZATION AND TARGET TRACKING IN THE ROBOCUP SIMULATION LEAGUE.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2006, Miami University
► In the growing field of mobile robotics, there is an increasing need…
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▼ In the growing field of mobile robotics, there is an increasing need to develop algorithms that allow a robot to interact with its environment. To do this effectively, a robot must use sensor readings to determine its own position (self-localization) and the positions of other robots in the environment (target-tracking). Because sensor readings are noisy, these algorithms generally must use probabilistic methods. One environment for which these algorithms are needed is the RoboCup Simulation League, a simulated soccer environment in which robots communicate with a soccer server to send commands and receive sensor data. In this thesis, we implement self-localization and target-tracking in the RoboCup environment. We develop the necessary probability models that allow these algorithms to perform well, and we propose an improved target-tracking algorithm that enhances performance in circumstances of high uncertainty and that enables the association of unique identifier values with targets.
Advisors/Committee Members: Zmuda, Michael A.
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8.
Elesev, Aleksandr.
Robot Localization Using Inertial and RF Sensors.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2008, Miami University
► A mobile robot must know its position in order to operate autonomously.…
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▼ A mobile robot must know its position in order to operate autonomously. The process of determining the robot's position from sensor data is termed robot localization. IMU and RF are a few of the many different types of sensors that can be used for navigation and localization purposes. When used independently, these sensors can achieve good accuracy when operating in certain conditions. By merging the results from multiple sensors, the accuracy over a wider range of conditions can be obtained. This work proposes a technique of merging heterogeneous information from inertial and RF sensors. Since sensors have errors associated with their readings, the robot's state will be represented using a probability distribution function (PDF). At each time step, this PDF will be updated based on the RF readings and then updated again based on the IMU readings. Better localization accuracy is obtained by using the RF and inertial sensors together.
Advisors/Committee Members: Zmuda, Michael.
Subjects: Artificial intelligence; Computer science; Robots
Keywords: robot localization; navigation; IMU; inertial sensors; RF; radio frequency sensors; particle filters; grid-based approach; PDF; probability density function; calibration
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9.
Gebre, Meseret Redae.
MUSE: A parallel Agent-based Simulation Environment.
Degree: MS, Computer Science and Systems Analysis, 2009, Miami University
► Realizing the advantages of simulation-based methodologies requires the use of a software…
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▼ Realizing the advantages of simulation-based methodologies requires the use of a software environment that is conducive for modeling, simulation, and analysis. Furthermore, parallel simulation methods must be employed to reduce the time for simulation, particularly for large problems, to enable analysis in reasonable timeframes. Accordingly, this thesis covers the development of a general purpose agent-based, parallel simulation environment called MUSE (Miami University Simulation Environment). MUSE, provides an Application Program Interface (API) for agent-based modeling and a framework for parallel simulation. The API was developed in C++ using its object oriented features. The core parallel simulation capabilities of MUSE were realized using the Time Warp synchronization methodology and the Message Passing Interface (MPI). Experiments show MUSE to be a scalable and efficient simulation environment.
Advisors/Committee Members: Rao, Dhanajai.
Subjects: Computer science
Keywords: Parallel Simulations; Time Warp; MPI; Agent-based Modeling; MUSE; Parallel Simulation Environment; C++ API
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10.
Geyer, Joseph Michael.
Identification of Candidate Concepts in a Learning-Based Approach to Reverse Engineering.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2010, Miami University
► Software reverse engineering is the process of extracting knowledge from a software…
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▼ Software reverse engineering is the process of extracting knowledge from a software system and then creating high-level abstractions to communicate that knowledge. This is vital to supporting long-term maintenance of the system. One such abstraction, or view, is to split the classes of the system into two sets -domain concept classes and peripheral classes. That is, the classes that relate to the domain of the system, and those classes that just help with the operation and functioning of the system. Supervised machine learning is a technique that can be used to label domain concept classes and peripheral classes given a training set. However, manually creating a training set is inefficient. The goal of the research is to present a method and tool to semi-automate the creation of a training set for using supervised learning to classify domain concept classes and peripheral classes in a software system.
Advisors/Committee Members: Gannod, Gerald.
Subjects: Computer science
Keywords: machine learning; reverse engineering; concept identification; automatic term recognition; active learning
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11.
Graessle, Robert James.
A Software-Defined Radio Based on the Unified SMSE Framework.
Degree: MS, Computer Science and Systems Analysis, 2010, Miami University
► The purpose of this research was to implement a software-defined radio based…
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▼ The purpose of this research was to implement a software-defined radio based on a recently developed framework for constructing various spectrally-modulated, spectrally-encoded (SMSE) signals. Two candidate waveforms (MC-CDMA and TDCS) are selected to demonstrate the capabilities of the framework, and they are modulated using antipodal signaling. A transmitter and receiver are each implemented on separate digital signal processor starting kits (DSK). A channel simulator consisting of additive white Gaussian noise and narrowband BPSK interferers is implemented on an FPGA. Burst transmissions from transmitter to receiver through the channel simulator are conducted to evaluate the bit-error rate performance of the system. Results from floating point simulation, fixed point simulation and hardware implementation are presented. The bit-error results from the hardware implementation closely match theoretical results. Also, TDCS is shown to mitigate effects of narrowband interference compared to MC-CDMA.
Advisors/Committee Members: Cheng, Chi-Hao.
Subjects: Electrical engineering
Keywords: Cognitive radio; Software-defined radio; SMSE; MC-CDMA; TDCS
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12.
Kandasamy, Meenakshi.
Approaches to Creating Fuzzy Concept Lattices and an Application to Bioinformatics Annotations.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2010, Miami University
► Recently, researchers have been developing methods to create fuzzy concept lattices from…
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▼ Recently, researchers have been developing methods to create fuzzy concept lattices from fuzzy formal contexts. These fuzzy concept lattices then serve as the basis for creating fuzzy ontologies which allow uncertain knowledge to be represented in ontology. This thesis research investigates two current approaches to create fuzzy concept lattices: the alpha-cut method and the fuzzy closure method, both of which have been implemented as part of this thesis research. Experimentation with the fuzzy closure method revealed that it produces an enormous number of formal concepts. A method to determine the more significant formal concepts within such huge fuzzy concept lattices is implemented using a factor analysis approach. The implementations are tested first with simple example fuzzy formal contexts. Then using the two approaches fuzzy concept lattices are created using the Gene Ontology and gene annotation data file. These two approaches to fuzzy concept lattice creation are then compared based on the results of these experiments. The factor analysis method is also applied to the various fuzzy formal contexts and the results analyzed with respect to those produced by the alpha-cut and the fuzzy closure methods. In addition, extensions to allow for fuzzy querying over the fuzzy concept lattices are implemented as part of the thesis research.
Advisors/Committee Members: Cross, Valerie.
Subjects: Computer Science
Keywords: FFCA; Ontology; Fuzzy Ontology; Fuzzy Closure Approach; Alpha Cut; Fuzzy Query; Compare Implication; Tnorm; Factor Analysis
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13.
Kauffman, Kyle J.
Fast Target Tracking Technique for Synthetic Aperture Radars.
Degree: MS, Computer Science and Systems Analysis, 2009, Miami University
► Modern radar imaging requires advanced Synthetic Aperture Radar (SAR) techniques in order…
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▼ Modern radar imaging requires advanced Synthetic Aperture Radar (SAR) techniques in order to compensate for the low resolution typically found on airborne radars. However, the techniques used to process the data collected during SAR operation require a great deal of computation. This paper proposes a novel efficient algorithm and approach to processing the data collected to quickly get high-resolution approximations for the locations of non-moving targets.
Advisors/Committee Members: Brinkman, William.
Subjects: Computer science; Electrical engineering
Keywords: SAR; computational efficiency; target detection; local search
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14.
Kaynak, Cihan.
Semantic Inconsistency and Computational Intractability in Transitive Abstraction Rules.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2008, Miami University
► Class diagrams in UML have the ability to capture the conceptual design…
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▼ Class diagrams in UML have the ability to capture the conceptual design view of a software system. Therefore, the abstraction of them has vital implications in reverse engineering and program comprehension. Building abstraction of class diagrams that are directly generated from source code is crucial to provide a maintenance engineer the ontology of a legacy system. Egyed proposed 121 transitive abstraction rules to discover UML relationships among classes that are related to domain concepts. In this work, we propose a number of modifications to Egyed’s rules that address some semantic inconsistencies. Furthermore, we prove that serial application of Egyed’s rules is inherently ambiguous in some cases and the identification of a semantically consistent abstraction is computationally intractable. Finally, we introduce a methodology that simplifies the set of abstraction rules introduced by Egyed.
Advisors/Committee Members: Gannod, Gerald.
Subjects: Computer science
Keywords: class diagram abstraction; design recovery; transitive abstraction rules; reverse engineering
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15.
Krumpe, Norman Joseph.
A COMPARISON OF SIMULATION OPTIMIZATION TECHNIQUES IN SOLVING SINGLE-OBJECTIVE, CONSTRAINED, DISCRETE VARIABLE PROBLEMS.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2005, Miami University
► Many analytic techniques are inadequate for finding optimal solutions to complex problems.…
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▼ Many analytic techniques are inadequate for finding optimal solutions to complex problems. Simulation is often used to model many such problems, but it is not always possible, or reasonable, to simulate every possible combination of control variables. Therefore, many simulation optimization techniques have been developed that attempt to iteratively search for a global optimum without testing every control parameter combination. The purpose of this study is to compare three such techniques: Simulated annealing, Hooke-Jeeves pattern search, and an algorithm that combines the essential features of simulated annealing and pattern search. These algorithms will be compared by applying them to several variants of three types of problems: two discrete-event simulations and one deterministic function. The results do not point to any one of these three algorithms outperforming the others. Rather results suggest that the performance of any of these algorithms depends on the many implementation decisions that must be made.
Advisors/Committee Members: Byrkett, Donald L.
Subjects: Computer Science
Keywords: simulation optimization; simulation; simulated annealing; hooke-jeeves pattern search; no-free-lunch theorem
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16.
Li, Hui.
Algorithms for the selection of optimal spaced seed sets for transposable element identification.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2010, Miami University
► Spaced seeds have proved to be invaluable in BLAST-like homology searches of…
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▼ Spaced seeds have proved to be invaluable in BLAST-like homology searches of large genomic sequences. But the problem of evaluating spaced seeds for this purpose is computational challenging, while the problem of finding optimal multi-seed sets is known to be NP-hard. In this thesis, we first explored the unpublished details and implemented the dynamic programming algorithm of the Li et al. PatternHunter group to address the problem of evaluating a multiple spaced seed set, and implemented our own version of this algorithm. We then developed a genetic algorithm to address the problem of optimal multi-seed set selection and found that our solutions superior to the greedy algorithm. Finally we implemented two additional tools with the goal of applying our results to the problem of transposable element identification.
Advisors/Committee Members: Karro, John.
Subjects: Bioinformatics; Computer science
Keywords: spaced seed set; genetic algorithm; hit probability; transposable element; greedy algorithm
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17.
Moler, James C.
Optimizing Approaches for Sensitive, High Performance Clustering of Gene Expressions.
Degree: MS, Computer Science and Systems Analysis, 2011, Miami University
► This thesis presents several new algorithmic approaches to the problem of clustering…
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▼ This thesis presents several new algorithmic approaches to the problem of clustering conventional ESTs and high throughput gene expression data, which are implemented in the software tool PEACE. The d2 algorithm for sequence comparison is improved and enhanced with a novel two-pass extension, and a minimum spanning tree-based algorithm is used to cluster ESTs, providing an efficient and accurate solution. Furthermore, in order to address the unique challenges of high throughput sequencing technologies such as 454, Illumina and SOLiD sequencing, an adaptive d2 algorithm is introduced to handle variations in fragment length. The resulting tool compares favorably with other leading tools in the literature, including WCD, CAP3, and TGICL, on both EST and next-generation sequencing (NGS) data.
Advisors/Committee Members: Karro, John.
Subjects: Bioinformatics; Computer Science
Keywords: clustering gene expressions; EST
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18.
Nalli, Sehar K.
SYNCHRONIZED TOKEN GENERATOR SYSTEM.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2006, Miami University
► This thesis discusses a novel methodology to protect a user’s credentials in…
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▼ This thesis discusses a novel methodology to protect a user’s credentials in a centralized LDAP authentication environment. The work discusses the design and implementation of the Synchronized Token Generator System that gives the user a temporary token they can use when authenticating to untrusted third-parties such as service providers. This methodology addresses the risk when users give their credentials to a service provider. In LDAP environment it is necessary to give the service provider the user’s actual credentials since the service provider sends these credentials to the central server for authentication. The service providers have plaintext access to the username/password pair (the user’s credentials) even when transmissions are encrypted and the service providers can easily store a copy of the user’s credentials. This research looked at existing solutions to this problem and found that most require that the client programs participate in a secure credential exchange system. This work proposes a solution that does not require modifications to the client or service provider programs. The result is a Synchronized Token Generator System that automatically generates temporary tokens that the users use in place of their password during the authentication process.
Advisors/Committee Members: Campbell, Scott Thomas.
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19.
Nareshkumar, Nithyalakshmi.
Simulataneous versus Successive Learning in Neural Networks.
Degree: MS, Computer Science and Systems Analysis, 2005, Miami University
► Psychology experiments using human subjects to study simultaneous versus successive learning for…
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▼ Psychology experiments using human subjects to study simultaneous versus successive learning for a discrimination task were replicated using neural networks. The two types of learning were defined by the manner in which the stimuli were supplied to the subjects. Simultaneous and successive learning were defined by the type of the neural network (batch and iterative) and the order of the training data. The results of the experiments were similar to but did not exactly match those obtained by psychologists. The experiments were extended to incorporate larger data sets and variations of the parameters involved. Conducting such experiments led to better understanding of various neural network features, thereby providing benefit to neural network research. Further validation can help psychologists establish neural networks as a tool for their experiments. Thus this study lays the foundation for an inter-disciplinary study, which could evolve into a symbiotic relationship between machine learning and psychology.
Advisors/Committee Members: Choi, Anthony.
Subjects: Computer Science
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20.
Obonyo, Victor Oduor.
Smartpen Technology and Revitalization of The Myaamia Language.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2009, Miami University
► The main purpose of this research is to determine whether appropriate technology…
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▼ The main purpose of this research is to determine whether appropriate technology can contribute towards revitalization of the Myaamia language. Language revitalization refers to the development of programs and other learning opportunities that result in re-establishing a language, which has ceased being the language of communication, and bringing it back into use in everyday life. Although it seems possible that various technologies can play an important role in these efforts, a survey of language revitalization programs has shown little assessment of the role of technology in language revitalization. In this project, a case study was done to determine, to what extent, if any, appropriately designed technology (in this case a Smartpen) can be useful in Myaamia language revitalization efforts. The result collected, after participants had used the research material, showed that technology, if configured appropriately and made interesting and purposeful, can play an important role in language revitalization efforts.
Advisors/Committee Members: Troy, Douglas.
Subjects: Computer science; Language; Linguistics
Keywords: Language Revitalization, Smartpen Technology, Myaamia Language, Penlet, Anoto Technology, Livescribe
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21.
Olson, Andrew Stephen.
A Software System for Solving Metric Emebedding Problems Using Linear Programming.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2006, Miami University
► Many of the most intensively studied problems in computer science concern metric…
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▼ Many of the most intensively studied problems in computer science concern metric spaces, sets of points with an attached distance measure. The use of metric embedding has lead to a revolution in the design of algorithms for the geometric domain. One particularly important metric space is the real vector space under the l1 norm, also known as the Manhattan Distance Metric. Current techniques for generating l1 embeddings, however, are time consuming and inflexible. To be successful an experimenter needed expertise in programming, optimization, and the geometry of l1 spaces. This paper discusses the implementation of a software tool that automates the process of experimenting with metric embeddings. Once an embedding is generated, the user is able to retrieve information regarding the embedding, and to manipulate the structure of the embedding via user-defined constraints. This system minimizes disk access, allowing it to be more efficient than previous l1 embedding implementation techniques.
Advisors/Committee Members: Brinkman, William John.
Subjects: Computer Science
Keywords: Linear Programming; Metric Embedding
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22.
Pal, Anindita.
AN ONTOLOGY ANALYSIS TOOL FOR CONSUMER.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2006, Miami University
► Ontologies capture domain knowledge in a generic way and provide a commonly…
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▼ Ontologies capture domain knowledge in a generic way and provide a commonly agreed understanding, and as such, are becoming the backbone of the Semantic Web. They are reused, shared, and applied across applications and groups. Various approaches to evaluating the quality of an ontology have been proposed and depend on the purpose of evaluation. Some evaluate ontologies for correctness, completeness and redundancy so that applications do not use poorly or incorrectly formulated ontologies. Others have developed methodologies to ensure the consistency and completeness of an ontology throughout its entire lifetime through the development and maintenance process. Recent proposals, however, suggest the importance of tools to help analyze ontologies for re-use by consumers. The objective of the thesis is the development of a consumer ontological analysis tool that can be used on any ontology, intensional or extensional, importable into Protégé, an ontology editor. This analysis tool is validated using four different ontologies, two well-known ontologies: WordNet and UMLS and two Product and Service Categorization Standards ontologies: UNSPSC and eCl@ss. A framework for ontology visualization is established and used to display selected results of the ontology analysis. This framework serves as the foundation for future research in ontology visualization.
Advisors/Committee Members: Cross, Valerie.
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23.
Pan, Jie.
Nonlinear Electrical Compensation For The Coherent Optical OFDM System.
Degree: MS, Computer Science and Systems Analysis, 2010, Miami University
► One major drawback of a Coherent-Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) system…
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▼ One major drawback of a Coherent-Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) system is its sensitivity to fiber nonlinearity. It has been shown that a Volterra series based nonlinear equalizer can compensate distortion introduced by the fiber nonlinearity. One major disadvantage of Volterra series is its complexity which can be reduced by removing its “unimportant” coefficients. The resulting Volterra system is called the sparse Volterra system. The Wiener-Hammerstein model is another popular nonlinear signal processing technique with a simpler structure. In this thesis, the nonlinear distortion of a CO-OFDM system is investigated, and equalizers based on Volterra model, sparse Volterra model and Wiener-Hammerstein model are designed. This is the first attempt to apply the Wiener-Hammerstein model to compensate nonlinear distortion in optical communication systems. A comparison between predistorters and equalizers is also presented. To the best of author’s knowledge, no such a study has ever been conducted for optical communication systems.
Advisors/Committee Members: Cheng, Chi-Hao.
Subjects: Electrical Engineering
Keywords: Nonlinear distortion, Nonlinear systems, Volterra series, Wiener-Hammerstein model,Equalizers, Predistorter,Orthogonal functions, Optical fiber communication, OFDM
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24.
Pei, Zhisong.
ONTOSELF+TQ: A TOPOLOGY QUERY SYSTEM FOR ONTOSELF.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2009, Miami University
► Research in ontology visualization provides software tools for ontology users to understand…
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▼ Research in ontology visualization provides software tools for ontology users to understand the structure of and to navigate through the complexity of a large ontology. OntoSELF was previously developed to provide a sophisticated user the ability to combine various weighting and filtering options to create a 3D ontology visualization. The inexperienced user, however, may have difficulty using OntoSELF since it requires mastery of technical details to produce the desired visualization. To allow novice users to easily perform topology understanding tasks on ontologies, the topology query (TQ) system OntoSELF+TQ has been developed. Users of OntoSELF+TQ can specify characteristics and constraints on components of the ontology to produce a visualization that helps them better understand the topology of the ontology. The querying capabilities of OntoSELF+TQ are demonstrated and evaluated through a small user study and system performance evaluations that exercise a wide variety of queries for numerous tasks common to understand ontologies.
Advisors/Committee Members: Cross, Valerie.
Keywords: ontology; visualization; software
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25.
Poudel, Pawan.
Computing point-to-point shortest path using an approximate distance oracle.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2008, Miami University
► We propose an extremely simple and efficient shortest path algorithm that computes…
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▼ We propose an extremely simple and efficient shortest path algorithm that computes an optimal shortest path between a pair of points in a metric space. Our algorithm works similarly to Dijkstra’s algorithm, but uses heuristic information provided by an approximate distance oracle to prune nodes that cannot be on the shortest path. Our algorithm returns the exact shortest path in time (CS*)O(dim) using this linear size data structure, where S* is the number of vertices in the shortest path, dim is the doubling dimension of input graph, and C is a constant. We prove that this is nearly optimal by proving a lower-bound of (CS*)Ω(dim). This paper presents theoretical and experimental results to prove that if there exist efficient distance oracles for road maps, then our algorithm explores very few nodes compared to Dijkstra’s algorithm, A* algorithm, and Goldberg, et al’s ALT algorithms.
Advisors/Committee Members: Brinkman, William.
Subjects: Computer science
Keywords: APPROXIMATE DISTANCE ORACLE; SHORTEST PATH; vertices
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26.
Rajendran, Venkatprabhu.
Recognizing Table Formatting From Text Files.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2006, Miami University
► Some text documents, legacy documents in particular, do not format sections of…
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▼ Some text documents, legacy documents in particular, do not format sections of text containing tables. Documents like these are not as readable as they could be since the columns are not aligned. Non aligned columns prevent the reader from seeing the important patterns in the text. This thesis presents algorithms to help insert table formatting into free text. This algorithm parses the text to identify common syntactic patterns such as dates, dollar amounts, and times. Pattern matching techniques are then used to identify models of what type of data each column should contain. These models are called templates. Ambiguities often exist. These ambiguities make it necessary to rank the alternative templates and their associated tables. This thesis focuses on evaluating the candidate templates and associated tables to rank the different alternatives. The scoring function attempts to mimic the process that a human might go through when performing the same task. The effectiveness of the scoring is evaluated on a set of tables that have appeared in real electronic feeds.
Advisors/Committee Members: Zmuda, Michael A.
Subjects: Computer Science
Keywords: Pattern Matching Techniques; Entities; Templates; Evaluation; Scoring Function
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27.
Roberts, David Anthony.
Discontinuous Systems Analysis: an Interdisciplinary Analysis Tool.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2007, Miami University
► The field of discontinuous mechanical systems in widely unexplored and lacks the…
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▼ The field of discontinuous mechanical systems in widely unexplored and lacks the definition and tools which accompany continuous mechanical systems. Designing and compiling a successful set of tools, or engineering toolkit requires the study of a number of areas, including user interface design and human computer interactions (HCI). This thesis presents the design, implementation and usability study of an interdisciplinary tool, for the aide and benefit of analysing discontinuous systems in mechanical engineering. The structure of the underlying framework, the design decisions, the design rational, and a comparison of multi-platform frameworks are also included.
Advisors/Committee Members: Shukla, Amit.
Keywords: DISCONTINUOUS SYSTEMS; DISCONTINUOUS; Matlab; Illustration; usability; user interface
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28.
Smith, Jason.
A Sensor Fault Detection Simulation Tool.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2007, Miami University
► As the demand for fault detection of sensors increases in the field…
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▼ As the demand for fault detection of sensors increases in the field of autonomous mobile robots, a tool is needed to easily allow sensor fault detection algorithms to be compared and analyzed. The focus of this thesis is on the development of such a tool. More specifically, this work presents a demonstration of the tool by comparing two sensor fault detection algorithms: the interacting multiple model (IMM) estimator and the simple fault detector (SFD). The IMM is a well known algorithm and is highly regarded in literature. The SFD is a novel algorithm. The simulation tool was written in C# and was used to simulate a four-wheeled robot with four navigation sensors. The user interface allows the user to select a predefined path type for the robot to traverse, specify its length, and cause any sensor to fail during a simulation run.
Advisors/Committee Members: Morton, Jade.
Keywords: robots; IMM; FAULT; SFD; SENSOR FAULT; SENSOR; linear velocity
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29.
Snow, Bradford Jason.
A Personal Place Awareness System.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2005, Miami University
► Place awareness is a fundamental component of a pervasive, context-aware system. A…
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▼ Place awareness is a fundamental component of a pervasive, context-aware system. A common approach to indoor localization is to use signal strengths from nearby 802.11b access points to estimate a position and then determine place based on position. These systems rely on a pre-built signal strength map relating position to a signal strength vector. This thesis proposes a system that is aware of place but does not require an a priori signal strength map relating a position (coordinates) to a signal strength vector. Instead, the system determines place by comparing observed signal strength vectors to a Bayesian model trained on data previously collected at known locations. This paper describes novel algorithms used to estimate place and presents experimental results. In addition, it discusses how the described techniques can be used to create a personal place awareness system that is simple enough to be deployed and maintained by a single end-user.
Advisors/Committee Members: Bachmann, Eric R.
Subjects: Computer Science
Keywords: pervasive computing; location-awareness; context-aware; ubquitous computing; wifi fingerprint; wifi location
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30.
Somasundaram, Ramanathan.
ONTOSELF: A 3D ONTOLOGY VISUALIZATION TOOL.
Degree: Master of Computer Science, Computer Science and Systems Analysis, 2007, Miami University
► Ontologies are frequently used to formalize the conceptualization of a domain. Numerous…
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▼ Ontologies are frequently used to formalize the conceptualization of a domain. Numerous ontologies exist in a variety of domains. For example, The United Nations Standard Products and Services Code (UNSPSC) ontology and the North American Industrial Classification System ontology (NAICS) are becoming widely used in e-commerce applications and contain on the order of thousands of product categories. The Gene Ontology (GO) with over 22,000 terms is widely used in biomedical applications. Useful techniques for visualizing the overall structure are needed by both ontology users and creators to understand their structure at a high level and then be able to navigate through the levels of complexity within the ontology. Researchers in ontology visualization are beginning to recognize that ontologies demand their own specialized tools with visualization techniques that depend strongly on both the characteristics of the presented information and the supported task requiring the visualization. This thesis develops a flexible ontology 3D visualization system called OntoSELF (Ontology Scrutiny Exploiting Layouts and Filtering) that allows a user to better understand the nature and identity, i.e., self, of an ontology. It provides a variety of weighting functions from concept-lattice drawing techniques and modifies the layout based on a user-selected weighting function. OntoSELF provides very adjustable filtering capabilities based on structural metrics determined for each ontology concept. Through filtering and flexible layout, the user can then focus on particular areas of the ontology where concepts meet the criteria the user deems essential for better understanding the structure of the ontology, either to hide or abstract out complexity or to reveal intricate details of the ontology. A variety of ontologies varying in domain knowledge and sizes and a set of topology understanding tasks are used to investigate the performance of OntoSELF. To make the testing process more efficient, the capability of parallel execution of both a variety of weighted visualization layouts and filtering options on one ontology and one visualization layout and filtering option on multiple ontologies is provided.
Advisors/Committee Members: Cross, Valerie V.
Subjects: Computer Science
Keywords: Ontology Visualization; 3D Ontology Visualization; Ontology Filtering; Ontology Layout; Ontology Visualization Tool; Parallel Ontology Visualization
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