Browsing by Subject "Communication"

Now showing 1 - 20 of 59

Open Access
2-D triangular mesh-based mosaicking for object tracking in the presence of occlusion
(SPIE, 1997) Toklu, C.; Tekalp, A. M.; Erdem, A. Tanju
In this paper, we describe a method for temporal tracking of video objects in video clips. We employ a 2D triangular mesh to represent each video object, which allows us to describe the motion of the object by the displacements of the node points of the mesh, and to describe any intensity variations by the contrast and brightness parameters estimated for each node point. Using the temporal history of the node point locations, we continue tracking the nodes of the 2D mesh even when they become invisible because of self-occlusion or occlusion by another object. Uncovered parts of the object in the subsequent frames of the sequence are detected by means of an active contour which contains a novel shape preserving energy term. The proposed shape preserving energy term is found to be successful in tracking the boundary of an object in video sequences with complex backgrounds. By adding new nodes or updating the 2D triangular mesh we incrementally append the uncovered parts of the object detected during the tracking process to the one of the objects to generate a static mosaic of the object. Also, by texture mapping the covered pixels into the current frame of the video clip we can generate a dynamic mosaic of the object. The proposed mosaicing technique is more general than those reported in the literature because it allows for local motion and out-of-plane rotations of the object that results in self-occlusions. Experimental results demonstrate the successful tracking of the objects with deformable boundaries in the presence of occlusion.
Open Access
Advanced partitioning and communication strategies for the efficient parallelization of the multilevel fast multipole algorithm
(IEEE, 2010) Ergül O.; Gürel, Levent
Large-scale electromagnetics problems can be solved efficiently with the multilevel fast multipole algorithm (MLFMA) [1], which reduces the complexity of matrix-vector multiplications required by iterative solvers from O(N 2) to O(N logN). Parallelization of MLFMA on distributed-memory architectures enables fast and accurate solutions of radiation and scattering problems discretized with millions of unknowns using limited computational resources. Recently, we developed a hierarchical partitioning strategy [2], which provides an efficient parallelization of MLFMA, allowing for the solution of very large problems involving hundreds of millions of unknowns. In this strategy, both clusters (sub-domains) of the multilevel tree structure and their samples are partitioned among processors, which leads to improved load-balancing. We also show that communications between processors are reduced and the communication time is shortened, compared to previous parallelization strategies in the literature. On the other hand, improved partitioning of the tree structure complicates the arrangement of communications between processors. In this paper, we discuss communications in detail when MLFMA is parallelized using the hierarchical partitioning strategy. We present well-organized arrangements of communications in order to maximize the efficiency offered by the improved partitioning. We demonstrate the effectiveness of the resulting parallel implementation on a very large scattering problem involving a conducting sphere discretized with 375 million unknowns. ©2010 IEEE.
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Alaylı gazetecilikten mektepli gazeteciliğe geçiş: Ankara Üniversitesi Siyasal Bilgiler Fakültesi Basın Ve Yayın Yüksek Okulu’nun tarihi
(Bilkent University, 2020) İçöz, Arda; Ediboğlu, Berke; Çam, Bilge Sena; Aygen, Irmak; Erdal, Kerem
Bu araştırmada 1961 Anayasası ile basının ve eğitimin değişimi incelenmiş, Ankara Üniversitesi Basın ve Yayın Yüksek Okulu’nun kuruluşu ve geçirdiği süreçlerle beraber bu sürecin öncüleri ile bu sürece tanıklık eden öğrencilerin araştırması yapılmıştır. Basın ve Yayın Yüksek Okulu’nun eğitim sistemi, işleyişi ve verilen dersler bölümün temel amacını yansıtmaktadır. Basın ve Yayın Yüksek Okulu’nun başarıları, okul bünyesinde çıkarılmış olan Görünüm dergisi, okul radyosu ve çeşitli etkinlikler üzerinden de izlenebilmektedir. Basın ve Yayın Yüksek Okulu’ndan mezun kişiler tarafından kurulan ve günümüzdeki ismi Ankara Üniversitesi İletişim Fakültesi Mezunları Vakfı olan kurum, mezunları bir araya getirerek çeşitli etkinlikler düzenlemekte ve öğrencilere maddi yardımda bulunmaktadır. Basın Yayın Yüksek Okulu, ülkemiz medyası ve özellikle TRT üzerinde etkiler yaratmıştır. Basın ve Yayın Yüksek Okulu çeşitli sebeplerden dolayı İletişim Fakültesi’ne dönüştürülmüş ve çeşitli alanlarda çalışan ünlü isimler bu okuldan mezun olmuştur.
Open Access
Authorship attribution: performance of various features and classification methods
(IEEE, 2007-11) Bozkurt, İlker Nadi; Bağlıoğlu, Özgür; Uyar, Erkan
Authorship attribution is the process of determining the writer of a document. In literature, there are lots of classification techniques conducted in this process. In this paper we explore information retrieval methods such as tf-idf structure with support vector machines, parametric and nonparametric methods with supervised and unsupervised (clustering) classification techniques in authorship attribution. We performed various experiments with articles gathered from Turkish newspaper Milliyet. We performed experiments on different features extracted from these texts with different classifiers, and combined these results to improve our success rates. We identified which classifiers give satisfactory results on which feature sets. According to experiments, the success rates dramatically changes with different combinations, however the best among them are support vector classifier with bag of words, and Gaussian with function words. ©2007 IEEE.
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Basic constructs of systems philosophy
(1975) Laszlo, Ervin
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Bellek peşinde; bunları chat'ten beklemezdiniz
(2000) Çavdar, Ayşe
Open Access
Capacity analysis of a PMR system with DAB downlink
(IEEE, 2003) Şengül, Ersin; Can, B.; Akar, Nail; İder, Yusuf Ziya; Köymen, Hayrettin
Several trunked private mobile radio (PMR) systems have been designed over the last decade, most of which have symmetric downlink and uplink channel capacities. These systems may not be spectrally efficient in case of group or broadcast-based voice and data calls, a common feature of PMR systems. We propose a new asymmetric PMR system comprising a wideband OFDM-based downlink and a narrowband uplink, which not only achieves a better spectral efficiency but also can support high bit rate multimedia applications. The system is shown to have high trunking efficiency since all users are assumed to use the pool of channels available in the wideband downlink. In this paper, we study the performance and capacity of a private mobile radio system using a digital audio broadcasting (DAB) downlink. In particular, we study the efficiency of such a system for voice calls using voice activity detection and statistical multiplexing. Moreover, we show that, the efficiency of the system can significantly increase, if the incoming calls, which can not find an available channel, are allowed to wait a certain amount of time before occupying a channel.
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Communication studies as American studies
(1990) Czitrom, Daniel
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Communications research since lazarsfeld
(1987) Katz, Elihu
Open Access
A critique of Davidsonian theories of Metaphor
(2022-01) Gürsoy, Zeynep
With their rich imagery and unique effects they generate, metaphors have been used in a variety of discourse. But what are their functions in language and communication? Which mechanisms govern the metaphorical interpretation? These fundamental questions fueled dissensus between different theories of metaphor in philosophical and linguistic frameworks. In the emergence of this ongoing debate, Davidson’s rejection of a special category of metaphorical meaning and his characterization of metaphor in terms of a special effect had an influential role. Lepore and Stone side with the Davidsonian tradition. By stressing the creativity of the user against the conventionality of content, they argue that metaphorical content is open-ended and semantically indeterminate. Moreover, Lepore and Stone ground these arguments in their distinction between imagination and convention, as well as in the notion of conversational record, which are fundamental to their inquiry-based model of language and communication. In this thesis, I present a critique of Davidsonian theories of metaphor, by particularly focusing on their argument from open-endedness. I argue that we must distinguish between two types of metaphors: poetic/creative and ordinary. I claim that ordinary metaphors are not open-ended in the way Lepore and Stone understand them to be. By offering a new interpretation of open-endedness, I illustrate how literal content can, in this regard, be similar to metaphorical. To solve potential challenges of my radical view, rather than providing a pragmatic or contextualist account, I turn to Fillmore’s notion of frames and illustrate the role of information, embedded in lexical items, on our understanding of literal and metaphorical content.
Open Access
Detection of microcalcifications in mammograms using nonlinear subband decomposition and outlier labeling
(SPIE, 1997-02) Gürcan, M. Nafi; Yardımcı, Yasemin C.; Çetin, A. Enis; Ansari, R.
Computer-aided diagnosis will be an important feature of the next generation picture archiving and communication systems. In this paper, computer-aided detection of microcalcifications in mammograms using a nonlinear subband decomposition and outlier labeling is examined. The mammogram image is first decomposed into subimages using a nonlinear subband decomposition filter bank. A suitably identified subimage is divided into overlapping square regions in which skewness and kurtosis as measures of the asymmetry and impulsiveness of the distribution are estimated. A region with high positive skewness and kurtosis is marked as a region of interest. Finally, an outlier labeling method is used to find the locations of microcalcifications in these regions. Simulation studies are presented.
Open Access
Dynamic capacity management for voice over packet networks
(2003-06-07) Akar, Nail; Şahin, Cem
In this paper, dynamic capacity management refers to the process of dynamically changing the capacity allocation (reservation) of a pseudo-wire established between two network end points. This process is based on certain criteria including instantaneous traffic load for the pseudo-wire, network utilization, time of day, or day of week. Frequent adjustment of the capacity yields a scalability issue in the form of a significant amount of message processing in the network elements involved in the capacity update process. On the other hand, if the capacity is adjusted once and for the worst possible traffic conditions, a significant amount of bandwidth may be wasted depending on the actual traffic load. There is then a need for dynamic capacity management that takes into account the tradeoff between scalability and bandwidth efficiency. This problem is motivated by voice over packet networks in which end-to-end reservation requests are initiated by PSTN voice calls and these reservations are aggregated into one signal reservation in the core packet network for scalability. In this paper, we introduce a Markov decision framework for an optimal reservation aggregation scheme for voice over packet networks. Moreover, for problems with large sizes, we provide a suboptimal scheme using reinforcement learning. We show a significant improvement in bandwidth efficiency in voice over packet networks using aggregate reservations. © 2003 IEEE.
Open Access
Effects of signal randomization on performance of binary communications systems
(IEEE, 2010) Göken, Çağrı; Gezici, Sinan; Arıkan, Orhan
In this paper, effects of signal randomization are studied for binary communications systems. First, it is stated that the average probability of error for a power-constrained binary communications system is minimized when each symbol is randomized between at most two signal values. Then, a fixed detector is considered, and sufficient conditions under which its performance can or cannot be improved via signal randomization are presented. After that, the joint design of detectors and signal structures is studied, and an optimization problem is formulated to determine the optimal system parameters. Finally, numerical results are presented to exemplify the improvements via signal randomization. ©2010 IEEE.
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Eğitici radyo üstüne konuşmalar I
(1969) Sabuncu, Sevgi
Open Access
Energy reduction in 3D NoCs through communication optimization
(Springer Wien, 2015) Ozturk, O.; Akturk I.; Kadayif I.; Tosun, S.
Network-on-Chip (NoC) architectures and three-dimensional (3D) integrated circuits have been introduced as attractive options for overcoming the barriers in interconnect scaling while increasing the number of cores. Combining these two approaches is expected to yield better performance and higher scalability. This paper explores the possibility of combining these two techniques in a heterogeneity aware fashion. Specifically, on a heterogeneous 3D NoC architecture, we explore how different types of processors can be optimally placed to minimize data access costs. Moreover, we select the optimal set of links with optimal voltage levels. The experimental results indicate significant savings in energy consumption across a wide range of values of our major simulation parameters.
Open Access
Expanded video: creating an alternative reality through merging 360-degree video and Glitch Art
(2018-09) Aydınat, Melih
This thesis investigates the merging of 360-degree video with Glitch Art in a form of ‘Virtual Reality’ experience while creating an alternative reality. The technological development in the field of Virtual Reality made it through daily life. However, this development causes problems such as misidentifying 360-degree video as VR. On the other hand, the rise of Glitch Art aesthetics, what makes it another hot topic of video field. Through merging Glitch Art and 360-degree video, ‘Reciprocal Reality’ project aims to create a VR-like experience while leaving the meaning of it to the spectator, at the same time creating a communication between the artist and the spectator via noise.
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Feedback in social sciences : toward a reconceptualization of morphogeneses
(1975) Kim, John Y.
Open Access
Flora: a framework for decomposing software architecture to introduce local recovery
(John Wiley & Sons Ltd., 2009-07) Sözer, H.; Tekinerdoǧan, B.; Akşit, M.
The decomposition of software architecture into modular units is usually driven by the required quality concerns. In this paper we focus on the impact of local recovery concern on the decomposition of the software system. For achieving local recovery, the system needs to be decomposed into separate units that can be recovered in isolation. However, it appears that this required decomposition for recovery is usually not aligned with the decomposition based on functional concerns. Moreover, introducing local recovery to a software system, while preserving the existing decomposition, is not trivial and requires substantial development and maintenance effort. To reduce this effort we propose a framework that supports the decomposition and implementation of software architecture for local recovery. The framework provides reusable abstractions for defining recoverable units and the necessary coordination and communication protocols for recovery. We discuss our experiences in the application and evaluation of the framework for introducing local recovery to the open-source media player called MPlayer. Copyright 2009 John Wiley & Sons, Ltd.
Open Access
Generalized ID-based ElGamal signatures
(IEEE, 2007-11) Kalkan, Said; Kaya, Kamer; Selçuk, Ali Aydın
ID-based cryptography has been a very active area of research in cryptography since bilinear pairings were introduced as a cryptographic tool, and there have been many proposals for ID-based signatures recently. In this paper, we introduce the concept of generalized ID-based ElGamal signatures and show that most of the proposed ID-based signature schemes in the literature are special instances of this generalized scheme. We also obtain numerous new signatures from this generalized scheme which have not been proposed before. ©2007 IEEE.
Open Access
Hypergraph-theoretic partitioning models for parallel web crawling
(Springer, London, 2012) Türk, Ata; Cambazoğlu, B. Barla; Aykanat, Cevdet
Parallel web crawling is an important technique employed by large-scale search engines for content acquisition. A commonly used inter-processor coordination scheme in parallel crawling systems is the link exchange scheme, where discovered links are communicated between processors. This scheme can attain the coverage and quality level of a serial crawler while avoiding redundant crawling of pages by different processors. The main problem in the exchange scheme is the high inter-processor communication overhead. In this work, we propose a hypergraph model that reduces the communication overhead associated with link exchange operations in parallel web crawling systems by intelligent assignment of sites to processors. Our hypergraph model can correctly capture and minimize the number of network messages exchanged between crawlers. We evaluate the performance of our models on four benchmark datasets. Compared to the traditional hash-based assignment approach, significant performance improvements are observed in reducing the inter-processor communication overhead. © 2012 Springer-Verlag London Limited.