Bilgisayar Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://gcris.khas.edu.tr/handle/20.500.12469/45

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Now showing 1 - 8 of 8

Citation Count: 4
Accurate indoor positioning with ultra-wide band sensors
(Tubitak, 2020) Arsan, Taner
Ultra-wide band is one of the emerging indoor positioning technologies. In the application phase, accuracy and interference are important criteria of indoor positioning systems. Not only the method used in positioning, but also the algorithms used in improving the accuracy is a key factor. In this paper, we tried to eliminate the effects of off-set and noise in the data of the ultra-wide band sensor-based indoor positioning system. For this purpose, optimization algorithms and filters have been applied to the raw data, and the accuracy has been improved. A test bed with the dimensions of 7.35 m x 5.41 m and 50 cm x 50 cm grids has been selected, and a total of 27,000 measurements have been collected from 180 test points. The average positioning error of this test bed is calculated as 16.34 cm. Then, several combinations of algorithms are applied to raw data. The combination of Big Bang-Big Crunch algorithm for optimization, and then the Kalman Filter have yielded the most accurate results. Briefly, the average positioning error has been reduced from 16.34 cm to 7.43 cm.
Citation Count: 1
Bayesian estimation of discrete-time cellular neural network coefficients
(TUBITAK Scientific & Technical Research Council Turkey, 2017) Şenol, Habib; Özmen, Atilla; Şenol, Habib
A new method for finding the network coefficients of a discrete-time cellular neural network (DTCNN) is proposed. This new method uses a probabilistic approach that itself uses Bayesian learning to estimate the network coefficients. A posterior probability density function (PDF) is composed using the likelihood and prior PDFs derived from the system model and prior information respectively. This posterior PDF is used to draw samples with the help of the Metropolis algorithm a special case of the Metropolis--Hastings algorithm where the proposal distribution function is symmetric and resulting samples are then averaged to find the minimum mean square error (MMSE) estimate of the network coefficients. A couple of image processing applications are performed using these estimated parameters and the results are compared with those of some well-known methods.
Citation Count: 1
Hybrid MPI plus UPC parallel programming paradigm on an SMP cluster
(TUBITAK Scientific & Technical Research Council Turkey, 2012) Bozkuş, Zeki
The symmetric multiprocessing (SMP) cluster system which consists of shared memory nodes with several multicore central processing units connected to a high-speed network to form a distributed memory system is the most widely available hardware architecture for the high-performance computing community. Today the Message Passing Interface (MPI) is the most widely used parallel programming paradigm for SMP clusters in which the MPI provides programming both for an SMP node and among nodes simultaneously. However Unified Parallel C (UPC) is an emerging alternative that supports the partitioned global address space model that can be again employed within and across the nodes of a cluster. In this paper we describe a hybrid parallel programming paradigm that was designed to combine MPI and UPC programming models. This paradigm's objective is to mix the MPI's data locality control and scalability strengths with UPC's fine-grain parallelism and ease of programming to achieve multiple-level parallelism at the SMP cluster which itself has multilevel parallel architecture. Utilizing a proposed hybrid model and comparing MPI-only to UPC-only implementations this paper presents a detailed description of Cannon's algorithm benchmark application with performance results of a random-access benchmark and the Barnes-Hut N-Body simulation. Experiments indicate that the hybrid MPI+UPC model can significantly provide performance increases of up to double in comparison with UPC-only implementation and up to 20% increases in comparison to MPI-only implementation. Furthermore an optimization was achieved that improved the hybrid performance by an additional 20%.
Citation Count: 0
New 2-Edge-Balanced Graphs from Bipartite Graphs
(Wiley-Blackwell, 2016) Çalışkan, Cafer
Let G be a graph of order n satisfying that there exists lambda epsilon Z(+) for which every graph of order n and size t is contained in exactly. distinct subgraphs of the complete graph K-n isomorphic to G. Then G is called t-edge-balanced and. the index of G. In this article new examples of 2-edge-balanced graphs are constructed from bipartite graphs and some further methods are introduced to obtain more from old. (C) 2015 Wiley Periodicals Inc.
Citation Count: 1
New Infinite Families of 2-Edge-Balanced Graphs
(Wiley-Blackwell, 2014) Çalışkan, Cafer; Chee, Yeow Meng
A graph G of order n is called t-edge-balanced if G satisfies the property that there exists a positive for which every graph of order n and size t is contained in exactly distinct subgraphs of Kn isomorphic to G. We call the index of G. In this article we obtain new infinite families of 2-edge-balanced graphs.
Citation Count: 1
Partitioning 3-arcs into Steiner Triple Systems
(Wiley, 2017) Çalışkan, Cafer
In this article it is shown that there is a partitioning of the set of 3-arcs in a projective plane of order three into nine pairwise disjoint Steiner triple systems of order 13.
Citation Count: 2
Predictive control of a constrained pressure and level system
(TUBITAK Scientific & Technical Research Council Turkey, 2015) Arsan, Taner; Arsan, Taner; Varol, Hüseyin Selçuk
The focus of this paper is the implementation of a constrained predictive control algorithm implemented in Multi-Parametric Toolbox (MPT) which is a free MATLAB toolbox for design analysis and implementation of controllers for constrained linear nonlinear and hybrid systems. In general MPT is used for modeling systems offline. The novelty of this study is that real-time mode MPT is used in process control. We also combined the Model Predictive Control Toolbox with MPT. This novel controller is considered a real-time controller of level-pressure systems. In this study a special type of model predictive control algorithm the constrained continuous-time generalized control is used as a controller. The advantages of the controller are illustrated by comparing it to a decoupling PI control.
Citation Count: 5
Zero-crossing based demodulation of minimum shift keying
(2003) Kerestecioğlu, Feza; Kerestecioğlu, Feza
Minimum shift keying (MSK) modulation has features such as constant envelope compact spectrum and good error performance which are all desirable in many digital applications including mobile radio. Numerous receiver structures to demodulate MSK have been suggested such as correlation receivers differential detectors and frequency discriminators MSK is a form of biphase keying and can be detected by a zero-crossing based phase demodulator which gives near optimum performance. In this paper the bit error performance of a zero-crossing based coherent MSK demodulator is theoretically investigated and a closed-form expression for the bit error rate is derived. The results indicate that the demodulator performs within 0.8-1 dB of the theoratical optimum for MSK. Towards the goal of deriving probability of bit error it is also shown that under additive white Gaussian noise (AWGN) zero-crossing locations of MSK signals are Gaussian distributed except at very low signal-to-noise ratios.

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