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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.

Edge Preserving Smoothing With Directional Consistency

Sancar Yilmaz, Aysun 01 June 2007 (has links) (PDF)
Images may be degraded by some random error which is called noise. Noise may occur during image capture, transmission or processing and its elimination is achieved by smoothing filters. Linear smoothing filters blur the edges and edges are important characteristics of images and must be preserved. Various edge preserving smoothing filters are proposed in the literature. In this thesis, most common smoothing and edge preserving smoothing filters are discussed and a new method is proposed by modifying Ambrosio Tortorelli approximation of Mumford Shah Model. New method takes into edge direction consistency account and produces sharper results at comparable scales.

A Study On Conceptual Modeling In Simulation Systems: An Extended Methodology For Kama

Aysolmaz Bozlu, Banu E. 01 December 2007 (has links) (PDF)
Conceptual modeling is considered to be essential in simulation development activities. However, there are only a few research studies on how to develop conceptual models. One of the important and comprehensive approaches is the methodology developed under the leadership of METU Modeling and Simulation Center (MODSIMMER) for Turkish Armed Forces. The project suggests a methodology to develop mission space conceptual models (GUKAM), and provides a Conceptual Model Development Tool for C4ISR M&amp / S activities, which is named as KAMA-C4ISRMOS. KAMA methodology is developed to utilize conceptual models in requirements collection and analysis activities. Two improvement opportunities observed in KAMA approach are that, there are no methodologies defined to develop simulation space conceptual models / and although most approaches emphasize the importance of conceptual model to be used in design activities, no explanations are provided on how to do it. This thesis aims to suggest an extended KAMA methodology that, besides original KAMA properties, provides a method to develop simulation space conceptual model, and provides a guide to use conceptual model to develop design. To evaluate the suggested methodology, a case study is conducted on a synthetic environment project. In this way, implementation of the methodology on another simulation domain is depicted. Developed mission space and simulation space conceptual models and design artifacts are evaluated, and the effects of conceptual models on simulation development life cycle are discussed.

Semantic Enrichment For The Automated Customization And Interoperability Of Ubl Schemas

Yarimagan, Yalin 01 March 2008 (has links) (PDF)
Universal Business Language (UBL) is an initiative to develop common business document schemas to provide standardization in the electronic business domain. However, businesses operate in different industry, geopolitical, and regulatory contexts and consequently they have different rules and requirements for the information they exchange. In this thesis, we provide semantic enrichment mechanisms for UBL that (i) allow automated customization of document schemas in response to contextual needs and (ii) maintain interoperability among different schema versions. For this purpose, we develop ontologies to provide machine processable representations for context domains, annotate custom components using classes from those ontologies and show that using these semantic annotations, automated discovery of components and automated customization of schemas becomes possible. We then provide a UBL Component Ontology that represents the semantics of individual components and their structural relationships and show that when an ontology reasoner interprets the expressions from this ontology, it computes equivalence and class-subclass relationships between classes representing components with similar content. Finally we describe how these computed relationships are used by a translation mechanism to establish interoperability among schema versions customized for different business context values.

A Tool For Network Simulation Of Massively Multiplayer Online Games

Bozcan, Selcuk 01 September 2008 (has links) (PDF)
Massively multiplayer online games (MMOGs) have become highly popular in the last decade and now attract millions of users from all over the world to play in an evolving virtual world concurrently over the Internet. The high popularity of MMOGs created a rapidly growing market and this highly dynamic market has forced the game developers to step up competitively. However, MMOG development is a challenging and expensive process. In this study, we have developed a network simulation tool which can be used to model and simulate typical MMOGs that have client-server architectures. The main objective is to provide a simulation environment to MMOG developers that could be used to test, analyze and verify various aspects of the MMOG network architecture. We have also implemented a graphical user interface which allows constructing the simulation model visually. We have demonstrated the use of simulation tool by experimental simulations.

Rearchitecturing An Electronic Warfare System Based On Service Oriented Architecture

Erzurumlu, Baki 01 November 2008 (has links) (PDF)
In this work an electronic warfare system is restructured to service oriented architecture. Service Oriented Architecture (SOA) is a paradigm that realizes rapid and low cost system development. The most important characteristics of SOA are standard based interoperability, which allows services developed on different platforms to run together, and dynamic composition via discovery, which provides dynamic composition of application at runtime using the existing services. The old warfare system that was developed by ASELSAN Inc. contained embedded software and was designed using traditional object oriented techniques. In this thesis, we have extracted services out of the system and restructured the warfare system based on service oriented principles. In this thesis, we have focused on the dramatic effect of reusability when SOA is introduced to the electronic warfare system. To understand the effect of service orientation, the new system is evaluated in terms of line of code, memory consumption and extra CORBA interface communication overhead.

Developing A Strategic Information System For Construction Companies

Gunes, Tanyeli 01 December 2008 (has links) (PDF)
Problems and issues at project level have been the main concern of the construction management studies and construction professionals. Consequently, the long-term strategic issues at corporate level remained uncovered in construction companies. The complex and unique characteristics of the industrial context of construction also limited the adoption of strategic management concepts by the companies. Recently, however, changing business environment, increasing competition in construction arena and higher client expectations have been the drivers for a shift in perception of strategic thinking experienced by construction executives. It is realized that setting long-term strategies is the roadmap towards gaining sustainable competitive advantage by the firm. The focus on strategic management raised the question about the strategic information sources for construction industry. Unless the required information is provided to the professionals as an input, decisions of high quality are unattainable outputs. This indispensable need for information increased the awareness of the companies about information technology and consequently strategic information systems which have great significance in shaping the competitive strategy of the organization. Although the significance of strategic thinking and information systems are realized by construction companies, it is still a complex task to design a strategic information system since the information needed to make the critical strategic decisions are widely spread and lost among the other data related to daily activities. The main objective of this thesis is to develop a generic IT-supported strategic management tool integrating the scattered information which can aid the decision making process of construction executives. Strategic fields within the context of construction industry are extracted from previous researches and discussed by experts in order to reach the right information sources which are to be stored in a database and accessed by the users through interfaces. The applicability of the developed strategic information system is tested by a Turkish construction company on real construction projects. Finally, the benefits, shortcomings and potential future developments for the tool are discussed by referring to the case study.

A Metrics-based Approach To The Testing Process And Testability Of Object-oriented Software Systems

Yurga, Tolga 01 February 2009 (has links) (PDF)
This dissertation investigates the factors that affect testability and testing cost of object- oriented software systems. Developing a software program which eases the testing process by increasing testability is crucial. Also, to assess whether or not the testing effort and cost consumed or planned is adequate or not is another critical matter this dissertation aims to answer by composing a new way to evaluate the links between software design parameters and testing effort via source-based metrics. An automated metric plug-in is used as the primary tool for obtaining the metric measurements. Our study is based on the investigation of many open-source projects written in Java to achieve our goals. By the help of the statistical evaluation of project data, we both propose a new model to assess testing effort and testability, and find significant relations and associations between software design and testing effort and testability of object-oriented software systems via source-based metrics.

Secure Communication Channel Mechanisms For Isolated Networks

Karadag, Gokdeniz 01 December 2009 (has links) (PDF)
Current network security solutions are consisted of a single host, with network interfaces of the host connected to protected and external networks at the same time. This design ensures security by restricting traffic flow to a single point, where it can be examined and acted on by a set of rules. However, this design also has a flaw and a single point of failure, that being the vulnerabilities in the security device itself. An adversary would have unhindered access to protected networks if a vulnerability in the security device itself leads to its compromise. To prevent this possibility, high-security networks are completely isolated from external networks, by prohibiting any network connection and constituting a so-called air gap in between. But, data transfer needs do arise between external networks and high-security networks, and in current technology this problem does not have a solution without human intervention. In this theses, we propose a set of mechanisms that allows near-realtime data transfers between high-security network and external networks, without requiring any human intervention. The design consists of two hosts connected via a shared storage, transferring only application layer data between networks. This prevents attacks targeting network stacks of the security device&#039 / s OS, and confines a compromised security device to the network that it is already connected to. In case of a compromise the amount of possible unwanted traffic to and from the high-security network is vastly reduced.

A Prefetching Method For Interactive Web Gis Applications

Yesilmurat, Serdar 01 March 2010 (has links) (PDF)
A Web GIS system has a major issue of serving the map data to the client applications. Since most of the GIS services provide their geospatial data as basic image formats like PNG and JPEG, constructing those images and transferring them over the internet are costly operations. To enhance this inefficient process, various approaches are offered. Caching the responses of the requests on the client side is the most commonly implemented solution. However, this method is not adequate by itself. Besides caching the responses, predicting the next possible requests of the client and updating the cache with the responses for those requests provide a remarkable performance improvement. This procedure is called &ldquo / prefetching&rdquo / . Via prefetching, caching mechanisms can be used more effectively and efficiently. This study proposes a prefetching algorithm called Retrospective Adaptive Prefetch (RAP). The algorithm is constructed over a heuristic method that takes the former actions of the user into consideration. This method reduces the user-perceived response time and improves users&rsquo / navigation efficiency. The caching mechanism developed takes the memory capacity of the client machine into consideration to adjust the cache capacity by default. Otherwise, cache size can be configured manually. RAP is compared with 4 other methods. According to the experiments, this study shows that RAP provides better performance enhancements than the other compared methods.

Integration Of Fuzzy Object-oriented Multimedia Database Components

Demir, Utku 01 December 2010 (has links) (PDF)
Improvements in technology have increased the amount of human interactive systems that support visual and audial operations. Besides many others, especially the recent entertainment industry has been built on the digital world and processing large collections of multimedia materials. Having huge amount multimedia data revealed the need for efficient and effective ways of modeling, storing, addressing, and retrieving such huge data, mostly, the semantic contents in it. Although there are some database management systems that support multimedia objects by some add-ons or extensions, they are far away from satisfying user requests, which are usually based on similarity and semantic contents. In this study, the requirements of multimedia databases are analyzed. To satisfy such requirements, a database architecture which is specialized for multimedia objects is constructed and a conceptual data model, handling semantic multimedia contents is implemented. In the architecture, a semantic information extractor, a high-dimensional index structure and an intelligent fuzzy object-oriented database component are integrated through a coordinator structure. The proposed architecture is realized and a prototype system is implemented by tightly coupling several multimedia modules.

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