Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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1997 - 19999

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End date: 1999Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, Computer Engineering

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Now showing 1 - 9 of 9
  • Master Thesis
    Trajectory Prediction of Moving Objects by Means of Neural Networks
    (Izmir Institute of Technology, 1997) Barışık, Hakan; Aytaç, İsmail Sıtkı; Aytaç, İsmail Sıtkı
    Estimating the three-dimensional motion of an object from a sequence of object positions and orientation is of significant importance in variety of applications in control and robotics. For instance, autonomous navigation, manipulation, servo, tracking, planning and surveillance needs prediction of motion parameters. Although "motion estimation" is an old problem (the formulations date back to the beginning of the century), only recently scientists have provided with the tools from nonlinear system estimation theory to solve this problem eural Networks are the ones which have recently been used in many nonlinear dynamic system parameter estimation context. The approximating ability of the neural network is used to identifY the relation between system variables and parameters of a dynamic system. The position, velocity and acceleration of the object are estimated by several neural networks using the II most recent measurements of the object coordinates as input to the system Several neural network topologies with different configurations are introduced and utilized in the solution of the problem. Training schemes for each configuration are given in detail. Simulation results for prediction of motion having different characteristics via different architectures with alternative configurations are presented comparatively.
  • Master Thesis
    Image Classifcation by Means of Pattern Recognition Techniques
    (Izmir Institute of Technology, 1997) Güzel, Cumhur; Püskülcü, Halis
    Image classification plays an important role in many computer vision tasks such as surface inspection, shape determination etc. Various 2-D image classification techniques are investigated, assessed and a computational method to classifY the 2-D X-ray images is developed and evaluated in this study. Various pattern recognition techniques are devised for the solution of the image classification. Those techniques may be divided into mainly two groups. First one, is mathematical and statistical model based, second one, is the artificial neural network based techniques. We have concentrated on artificial neural network techniques. In the experiments, both techniques were applied for the classification of the VUR (vesico ureteral reflux) images, in this study. However, according to the experiments performed on VUR case study, neural network technique was more successful than others, in terms of classifier. A hybrid method is proposed in this study, rather than pure artificial neural network solution. Representation of images is performed via transformation invariant mathematical structure called Fourier Descriptors and these structures are used as input to train the neural network for the classification part.The application is performed as follows: Feature extraction is performed first, then extracted features are used as pattern vectors for training the neural network. Representation of the shapes in X-ray images is performed by using Fourier Descriptors. Usage of Fourier descriptors as a method of representation of the shapes, provides the transformation invariant' (translation, rotation, scaling invariant structure) representation of X-ray images. These new vector representation is fed to the neural network. Backpropagation is used as a training algorithm. After training is finished, system is readyfor questioning. The minimum-mean-distance and nearest neighbor rules are also applied for the pattern vectors generated for the experiments. But the multilayer perceptron trained by backpropagation outperforms both of these statistical classifiers.
  • Master Thesis
    Reconstruction of X-Ray Images
    (Izmir Institute of Technology, 1997) Aka, Hüseyin Cüneyt; Aytaç, İsmail Sıtkı
    We have presented an integrated approach in retrieving, reconstructing, and storing images obtained from noisy X-rays in this study. The X-ray images are used to detect human body's invisible parts. The problem of blurring and uneven illumination is always faced. Although it is partially solved by the physicians via lighting the X-rays, this method is not working properly in some cases such as Vesico Ureteral Reflux disease. This may cause loss of some meaningful part of the information and failure in diagnosis process. In order to decrease such errors, some computational methods has been developed by means of image processing. Due to its very nature, reconstruction, retrieving and registration of x-ray images has been chosen as a subject of this study. We have begun attacking the problem of reconstruction and extraction, then started to generate multi-layer hierarchical solutions. We have tried so many different approaches for each layer in our experiments. In each experiment, some methods produced accurate results, some methods did not. Thus, we have exerted every effort to optimize the solution for each layer. Although we have worked with limited number of sample images,(due to the problem of retrieving x-rays which is seen in this case) the results show us that, all the samples that we have processed, could have been reconstructed and stored as we have expected.Storing of the huge amount of data is an another problem in our area of interest, because of image characteristics. Every kidney image consists of nearly 120.000 (around 300x400) pixels. However, in our case, the boundaries of kidney region are sufficient for diagnosis. In other words, storing the boundaries instead of complete image has the same precision. We detected and stored the kidney's boundary coordinates on both x and y axis. Although this was sufficient for our study, we have decided to develop a much more flexible file format by ordering x and y coordinate couples in counter clockwise direction with the same information for further studies such as computer aided diagnosis systems.
  • Master Thesis
    Craniofacial Computer Assisted Surgical Planning and Simulation
    (Izmir Institute of Technology, 1999) Ekin, Emine; Aytaç, İsmail Sıtkı
    In this work, mainly, the first step of craniofacial surgical simulation and planning procedure, reconstruction of tomography images is investigated. The Direct Reconstruction techniques and algebraic methods are described in detailed mathematical formulations for both two and three-dimensional cases. And also a brief description of medical imaging techniques and the terminology of craniofacial surgical simulation and planning is given. In the last chapter the implementation details, the algorithms developed and some resulting images are given and the images are compared with respect to the used algorithms.
  • Master Thesis
    A Genetic Algorithmic Approach To the Differential and Linear Cryptanalysis
    (Izmir Institute of Technology, 1999) Eminağaoğlu, Mete; Koltuksuz, Ahmet Hasan
    The two most well known and recently developed methods in cryptanalysis of DES and DES-like symmetric block ciphers are difTerential and linear cryptanalysis. But these cryptanalytic attacks need to be improved due to the computational performance and storage capacity problems On the other hand, genetic algorithms can be a good solution in cases where the optimum value or near-optimum solutions are sought in complex systems or for non-linear problems. This is a valid situation for the cryptanalysis case where DES and DES-like ciphers are non-linear in structure making dilTerential and linear cryptanalysis a complex system with a very large search landscape and extreme amount of conditional and probabilistic candidates for the key being sought. In this study, a new and promising method wit h bet ter performance is to be developed for differential/linear cryptanalysis of DES and similar symmetric cryptosystems exploiting genetic algorithms' broadened search and optimum finding capacity.
  • Master Thesis
    Web Based User Accounting System for Internet Service Providers
    (Izmir Institute of Technology, 1999) Balcı, Murat; Aytaç, İsmail Sıtkı
    There are some basic operations, that any Internet Service Provider (ISP) must do, such as adding, removing users, disabling and enabling users, changing user passwords etc. Beside these basic operations, all ISPs must design a accounting system to bill the users. Most of the currently available ISP packages run on Windows NT or UNIX systems and in client side a specific client program is developed, which runs only on specific operating system (OS) (say Windows NT). If ISP want to access these ISP operations from an another OS (say from UNIX (with hundreds of its derivatives), OS/2, MacOS etc.), client program must be ported to each of the OS. Although this is possible in theory, in practice it is very difficult and not cost effective.In this thesis to solve this problem, a Web based user accounting system IS proposed. In a Web based system anyone who has a regular Web browser can access the ISP data, manage and view them (ofcourse securely) no-matter where he is in the world which OS he uses. This approach makes ISP accounting easy and cost effective. Additionally making the system in Turkish, increases the useability of the system for the Turkish users.
  • Master Thesis
    An Operating System for Data Acquisition and Control Applications
    (Izmir Institute of Technology, 1999) Ayav, Tolga; Aytaç, İsmail Sıtkı
    The common controllers used in industrial environments today cannot fulfill the requirements of many data acquisition and control applications. As a result of this, personal computers has become to be popular in industry, as they have been so in many areas due to the fact that today's PCs have many advantages compared with their relatively low price. In this project, a PC based embedded controller was designed for data acquisition and control purposes, and a real-time executive running on DOS operating system was developed.
  • Master Thesis
    Modelling of Turkey Turkish Words by Discrete Markov Processes
    (Izmir Institute of Technology, 1998) Güventürk, Jale; Koltuksuz, Ahmet Hasan
    This study based on the previous works of Assistant Prof. Dr. Ahmet Hasan KOLTUKSUZ, is about obtaining cryptanalytical measures of Turkey Turkish words based on Markov processes approach.
  • Master Thesis
    An Approch To the Security Problems in the Tcp/Ip Protocol Suite for a Network Security Monitor Design
    (Izmir Institute of Technology, 1999) Mutaf, Pars; Koltuksuz, Ahmet Hasan
    There are a number of security problems in the TCP/IP protocol suite. In this thesis these problems will be analyzed in detail. The problems in several existing prevention methods will be analyzed as well in order to show that security policies based merely on preventive measures are not completely secure and convenient. Therefore, "network security moniJoring" will be proposed as an alternative and supplementary approach against Internet attacks.