Mühendislik Fakültesi

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Citation - WoS: 0
Citation - Scopus: 0
A case study on web-based information system evaluation
(Acad Conferences Ltd, 2014) Tokdemir, Gul; Tokdemir, Gül; Bilgen, Semih; Ercil, Yavuz; 17411; Bilgisayar Mühendisliği
A new framework is proposed to assess web-based information systems (WISs) which is domain-independent, that is, can be applied for profit seeking as well as service oriented or non-profit seeking organizations. Assessment starts from an identification of the critical success factors (CSF) that outline organizational strategies, and proceeds to determine the measures of three categories of relationships: User-WIS, Other systems-WIS, Organization-WIS. These measures and CSF's are evaluated collectively to arrive at an effectiveness measure. A case study illustrating the applicability of the assessment framework in the e-business domain is presented.
Citation - Scopus: 33
A Collaborative and Content Based Event Recommendation System Integrated With Data Collection Scrapers and Services At A Social Networking Site
(IEEE Computer Society, 2009) Kayaalp, M.; Ozyer, T.; Ozyer, S.T.; 18980
There are many activities that people prefer/opt out attending and these events are announced for attracting people. An intelligent recommendation system can be used in a social networking site in order to recommend people according to content and collaboration assessment. This study is an effort to recommend events to users within a social networking site. It can be any networking environment. We have used social environment that has been designed as a facebook1 application. Our application has also been integrated with several web sites. System collects event data from several related web sites either by using web services or web scraping. It also permits users rating events they have attended or planned. Given the social network between people, system tries to recommend upcoming events to users. For this purpose a combination of content based and collaborative filtering has been used. We have also taken geographical location info and social concept of an event. © 2009 IEEE.
Citation - WoS: 0
Citation - Scopus: 0
A combined spatial and frequency based texture model for organsegmentation in computed tomography examinations
(Amer Scientific Publishers, 2014) Jafari, Aref; Hassanpour, Reza; Hassanpour, Reza; Shahbahrami, Asadollah; Wong, Stephan; Yazılım Mühendisliği
The organ segmentation in computed tomography (CT) examination is a tedious and error prone task. The local similarity of the pixels from different organs, and the differences between the pixels of the same organ observed in different examinations are two most challenging problems affecting the segmentation process. In this study, statistical and spectral texture properties are combined with the a-priori knowledge about the human body to develop a model for reliably segmenting organs in CT examinations. The main goal of the developed model is fusing local and global statistics to support spatial-frequency analysis and to maximize the simultaneous localization of energy in both spatial and frequency domains. The feature space dimension is reduced by means of a wrapper technique applied as a pre-processing filter. The proposed classifier utilizes a linear combination (ensemble) of two support vector machines (SVM) where the first SVM classifies the input samples according to their textural information and the second one correct the results of the first classifier by searching the spatial information of those samples in a statistical atlas.
Citation - Scopus: 0
A data collection system design for hand gestures
(Institute of Electrical and Electronics Engineers Inc., 2021) Akan, E.; Akagunduz, E.; Uslu, I.B.
In this study, we aim at designing a smart glove, which consists of different inertial sensors and an EMG sensor and developing a human-machine interaction application by pre-processing and fusing these different sensory data. We also aim at providing solutions in cases where image processing-based approaches are inefficient. In the proposed smart glove, the quaternion-based orientation data to be produced by the magnetometer and gyroscope together, the acceleration data to be generated by the accelerometer, and the analog data generated by the EMG sensor are collected and then prepared for use by different applications. © 2021 IEEE.
Citation - Scopus: 0
A Data Fusion Approach In Protein Homology Detection
(2008) Oğul, Hasan; Polatkan, A.C.; Oǧul, H.; Sever, Hayri; Sever, H.; 11916; Bilgisayar Mühendisliği
The discriminative framework for protein remote homology detection based on support vector machines (SVMs) is reconstructed by the fusion of sequence based features. In this respect, n-peptide compositions are partitioned and fed into separate SVMs. The SVM outputs are evaluated with different techniques and tested to discern their ability for SCOP protein super family classification on a common benchmarking set. It reveals that the fusion approach leads to an improvement in prediction accuracy with a remarkable gain on computer memory usage. © 2008 IEEE.
Citation - WoS: 0
Citation - Scopus: 2
A Discovery and Analysis Engine for Semantic Web
(Assoc Computing Machinery, 2018) Yumusak, Semih; Doğdu, Erdoğan; Kamilaris, Andreas; Dogdu, Erdogan; Kodaz, Halife; Uysal, Elif; Aras, Riza Emre; Bilgisayar Mühendisliği
The Semantic Web promotes common data formats and exchange protocols on the web towards better interoperability among systems and machines. Although Semantic Web technologies are being used to semantically annotate data and resources for easier reuse, the ad hoc discovery of these data sources remains an open issue. Popular Semantic Web endpoint repositories such as SPARQLES, Linking Open Data Project (LOD Cloud), and LODStats do not include recently published datasets and are not updated frequently by the publishers. Hence, there is a need for a web-based dynamic search engine that discovers these endpoints and datasets at frequent intervals. To address this need, a novel web meta-crawling method is proposed for discovering Linked Data sources on the Web. We implemented the method in a prototype system named SPARQL Endpoints Discovery (SpEnD). In this paper, we describe the design and implementation of SpEnD, together with an analysis and evaluation of its operation, in comparison to the aforementioned static endpoint repositories in terms of time performance, availability, and size. Findings indicate that SpEnD outperforms existing Linked Data resource discovery methods.
Citation - WoS: 0
Citation - Scopus: 4
A drift-reduced scheme for hierarchical wavelet coding scalable video transmissions
(Ieee, 2009) Choupani, Roya; Wong, Stephan; Tolun, Mehmet R.
Scalable video coding allows for the capability of (partially) decoding a video bitstream when faced with communication deficiencies such as low handwidth or loss of data resulting in lower video quality. As the encoding is usually based on perfectly reconstructed frames, such deficiencies result in differently decoded frames at the decoder than the ones used in the encoder and, therefore, leading to errors being accumulated in the decoder. This is commonly referred to as the drift error. Drift-free scalable video coding methods also suffer from the low performance problem as they do not combine the residue encoding scheme of the current standards such as MPEG-4 and H.264 with scalability characteristics. We propose a scalable video coding method which is based on the motion compensation and residue encoding methods found in current video standards combined with the scalability property of discrete wavelet transform. Our proposed method aims to reduce the drift error while preserving the compression efficiency. Our results show that the drift error has been greatly reduced when a hierarchical structure for frame encoding is introduced.
Citation - Scopus: 1
A Droplet Based Multi-Drug Screening System Controlled With Electrostatic Microvalves
(Chemical and Biological Microsystems Society, 2012) Yildirim, E.; Yıldırım, Ender; Özgür, E.; Külah, H.; 31835; Makine Mühendisliği
This paper presents a droplet-based drug effect analysis system utilizing electrostatically-actuated normallyclosed microvalves to screen the effect of multiple drugs on a single type of cell. Proposed system minimizes the need for off-chip equipment by utilizing parylene based electrostatic microvalves. Prototypes of the system were fabricated and tested using colored DI water and 3 μm diameter micro beads, emulating drugs and cells respectively. During the tests, micro beads could be successfully entrapped in 137 pl droplets. Tests carried out with yeast cells also yielded successful encapsulation of the cells. It was shown that, switching between the drugs could be achieved by applying 200 V dc to operate the microvalves.
A Hybrid Framework for Matching Printing Design Files to Product Photos
(2020) Akagunduz, Erdem; Kaplan, Alper; 233834
We propose a real-time image matching framework, which is hybrid in the sense that it uses both hand - crafted features and deep features obtained from a well -tuned deep convolutional network. The matching problem, which we concentrate on, is specific to a certain application, that is, printing design to product photo matching. Printing designs are any kind of template image files, created using a design tool, thus are perfect image signals. For this purpose, we create an image set that includes printing design and corresponding product photo pairs with collaboration of an actual printing facility. Using this image set, we benchmark various hand-crafted (SIFT, SURF, GIST, HoG) and deep features for matching performance. Various segmentation algorithms including deep learning based segmentation methods are applied to select feature regions. Results show that SIFT features selected from deep segmented regions achieves up to 96% product photo to design file matching success in our dataset. We propose a framework in which deep learning is utilized with highest contribution, but without disabling real-time operation using an ordinary desktop computer.
Citation - Scopus: 1
A Knowledge Visualization Model for Evaluating Internet News Agencies On Conflicting News
(2011) Medeni, I.T.; Medeni, İhsan Tolga; Peker, S.; Uyar, M.E.; 181215; Bilgisayar Mühendisliği
With the advent of the Internet, the news agencies have published news on their websites for the internet readers. This improvement enables Internet readers to access news easily and also to gain information and knowledge in real time manner. Since there are many online news agencies and online newspapers, readers generally have difficulty to decide which newspaper or agency provides the most reliable news. The reliability can be defined as using consistent and proper source of news especially on conflicting news but this increases news' source complexity. As a knowledge management technique, knowledge visualization is one of the ways for readers to decrease this complexity level. In this study, we propose a knowledge visualization model to identify success rates of the online news agencies and online newspapers regarding how consistent they are with the concluded actual news content. This model will be a baseline to indicate knowledge management capabilities of the agencies based on conflicted news categories. © 2011 MIPRO.
Citation - Scopus: 11
A Longest-Path Problem for Evaluating the Worst-Case Packet Delay of Switched Ethernet
(2010) Schmidt, K.; Schmidt, E.G.; 17337
In the recent years, the use of real-time Ethernet protocols becomes more and more relevant for time-critical networked industrial applications. In this context, this paper presents a method to compute the worst-case packet delays on switched Ethernet. Based on an evaluation of the packet delays at each switch port and the network topology, we construct a weighted directed graph that allows to find the worst-case end-toend packet delay by solving a conventional longest-path problem. © 2010 IEEE.
Citation - Scopus: 1
A New Companding Technique for Papr Reduction in Ofdm Communication Systems
(2011) Gazi, O.; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
One of the major disadvantages of OFDM communication systems is their high peak-to-average power ratio (PAPR) which degrades system performance when nonlinear power amplifiers are employed. Among the proposed PAPR tech- niques companding is favorable due to its simplicity and easy of implementation. In this article, using the arctan- gent function we propose a new compading technique for PAPR reduction. We compare the proposed technique to the previously suggested exponential companding, and μ- law companding methods. Via computer simulations it is verified that the proposed technique is better than exponen- tial and μ-law companding methods for PAPR reduction.
Citation - Scopus: 30
A New Design of Dual Band Microstrip Bandpass Filter Based On Peano Fractal Geometry: Design and Simulation Results
(2013) Mezaal, Y.S.; Eyyuboglu, H.T.; Ali, J.K.; 7688
The proposed filter design topology is based on dual coupled resonators constructed in the form of Peano fractal geometry. A dual-band microstrip bandpass filter with a quasi-elliptic response has been designed for first time based on 1st iteration Peano fractal geometry at resonant frequencies of 2.25 GHz and 4.825 GHz using a substrate of a relative dielectric constant of 10.8 and thickness of 1.27 mm. The performance of the bandpass filter structure has been analyzed using a method of moments (MoM) based software package, Microwave Office 2009, from Advanced Wave Research Inc. Results show that this filter possesses good frequency response characteristics in addition to dual bands gained which can be used for modern communication applications. © 2013 IEEE.
Citation - WoS: 5
Citation - Scopus: 31
A New Narrow Band Dual-Mode Microstrip Slotted Patch Bandpass Filter Design Based On Fractal Geometry
(Ieee, 2012) Mezaal, Yaqeen S.; Eyyuboglu, Halil Tanyer; 7688
A narrowband, compact, and easily fabricated microstrip bandpass filter design is introduced in this paper as a candidate for use in modern wireless systems. The proposed filter design is based on the use of dual-mode (two pole) square slotted microstrip resonator. This microstrip bandpass filter has the advantages of possessing much narrower and sharper performance responses than those of the single mode resonator and conventional square patch filter. The proposed microstrip filter structure is fractally generated using Sierpinski fractal curve geometry applied to the conventional square microstrip patch. Filter structures resulting from the successive iterations in the fractal generation process show a considerably low insertion loss, and sharper response of about 1% fractional bandwidth as compared with the conventional microstrip square patch filter of 3% fractional bandwidth designed at the same frequency using the same substrate material. The performance of filter structures, based on dual-mode resonators up to the third iterations, has been evaluated using a full-wave based electromagnetic simulator Sonnet software package. Performance simulation results show that these filter structures offer narrower fractional bandwidth percentages as compared with other types of non- fractalized filter structures.
Citation - WoS: 4
Citation - Scopus: 27
A Novel Design of Two Loosely Coupled Bandpass Filter Based On Hilbert-Zz Resonator With Higher Harmonic Suppression
(Ieee, 2013) Mezaal, Yaqeen S.; Eyyuboglu, Halil T.; Ali, Jawad K.; 7688
New characteristics of fractal design scheme has been introduced to generate compact two poles capacitively coupled microstrip bandpass filter by using additional coupling stubs for different wireless applications. The presented fractal scheme is based on specific type of Hilbert space-filling curve which is called Hilbert-zz fractal geometry. The performance of generated bandpass filter structure has been analyzed using Sonnet software package with a relative dielectric constant of 9 and a substrate thickness of 1.27 mm. Results show that these filters possess good transmission and return loss characteristics, besides higher harmonics suppressions; meeting the specifications of most of wireless communication systems.
Citation - WoS: 0
A Novel Hypercube-based Approach to Overlay Design Algorithms on Topic Distribution Networks
(Gazi Univ, 2022) Yumusak, Semih; Hassanpour, Reza; Layazali, Sina; Oztoprak, Kasim; Hassanpour, Reza; Yazılım Mühendisliği
Data communication in peer-to-peer (P2P) network requires a fine-grained optimization for memory and processing to lower the total energy consumption. When the concept of Publish/subscribe (Pub/Sub) systems were used as a communication tool in a P2P network, the network required additional optimization algorithms to reduce the complexity. The major difficulty for such networks was creating an overlay design algorithm (ODA) to define the communication patterns. Although some ODAs may perform worse on a high-scale, some may have better average/maximum node degrees. Based on the experimentation and previous works, this study designed an algorithm called the Hypercube-ODA, which reduces the average/maximum node degree for a topic connected Pub/Sub network. The Hypercube-ODA algorithm creates the overlay network by creating random cubes within the network and arranging the nodes with the cubes they belong to. In this paper, the details of the proposed Hypercube algorithm were presented and its performance was compared with the existing ODAs. Results from the experiments indicate that the proposed method outperforms other ODA methods in terms of lower average node degree (lowering the average node degree by up to 60%).
A Novel Method For Performance Improvement of Slow Start Congestion Control Method In Packet Switched Networks
(2019) Preveze, Barbaros; Preveze, Barbaros; 17573; Elektrik-Elektronik Mühendisliği
Tüm akıllı ağlar, akıllı telefonlar, araç multimedya sistemleri giyilebilir teknolojiler ve IP TV'ler ile tanışılmasıyla birlikte internet bağlantılı cihaz ve uygulamaların sayısı da oldukça artmaktadır. Bu durum, paket anahtarlama ağlarında bant genişliği kullanımı miktarında artışa sebep olmuştur. Böylece, bant genişliğinin etkin kullanımı ve sistem performansı daha önemli hale gelmiştir ve literatürde ağ performansını iyileştirmeye çalışan çok sayıda çalışma bulunmaktadır. Ağ yapılarında finansal destek gerektiren donanım tabanlı modifikasyonlar yapmak yerine daha çok, kullanılan yöntemlerin yazılımsal modifikasyonları tercih edilmektedir. Bu çalışmada, daha iyi bir tıkanıklık kontrolü için paket anahtarlamalı ağlarda Eşiğe Geri Dön (RBT) adı verilen yeni bir yöntem önerilmiştir.
Citation - WoS: 0
A Petri Net-based inference network for design automation under nondeterminism applied to mechatronic systems
(Pergamon Press Ltd, 1998) Erden, Z; Erkmen, AM; Erden, A
This paper introduces the completed part of an ongoing research, in which a Petri Net-based design inference network is developed for the representation and analysis of the functions and their interrelationships through information flow for the conceptual design stage of mechatronic systems in order to facilitate design automation. The theoretical framework behind the network is based on transition of Hybrid Automata into Petri Nets and application of this framework is introduced by a mechatronic design example.
Citation - Scopus: 13
A Proposed Method of Photovoltaic Solar Array Configuration Under Different Partial Shadow Conditions
(Trans Tech Publications Ltd, 2014) Humada, A.M.; Hojabri, M.; Mohamed, M.B.; Bin Sulaiman, M.H.; Dakheel, T.H.
The benefit of improving the efficiency of photovoltaic (PV) solar system has come into view because of increasing the demand for electricity, especially in the urban areas. However, these PV solar systems are vulnerable to the mismatch operating conditions. Under such conditions, the performance of solar cells has decreased rapidly since the nonuniform insolation hitting the cells and with different values. Then this leads to cause rapidly decreasing in the output power value and maximum power point, beside to hot spot points that may be occurring in the solar cell which finally leads to damage these cells. This paper proposes an optimal connection of substrings with different value of shadow conditions, based on a thorough configuration that can significantly reduce that nonuniform condition loss. The refinement over existing photovoltaic (PV) solar array interconnections is proven by extensive simulation results by using MATLAB SIMULINK. © (2014) Trans Tech Publications, Switzerland.
Citation - WoS: 12
Citation - Scopus: 13
A Reconfigurable Microfluidic Transmitarray Unit Cell
(Ieee, 2013) Erdil, Emre; Yıldırım, Ender; Topalli, Kagan; Zorlu, Ozge; Toral, Taylan; Yildirim, Ender; Kulah, Haluk; Civi, Ozlem Aydin; 31835); Makine Mühendisliği
This paper presents a novel microfluidics based approach to develop a reconfigurable circularly polarized transmitarray unit cell. The unit cell comprises double layer nested split ring slots formed as microfluidic channels that can be filled by fluids. Split regions in the slots are realized by injecting liquid metal into the channels. Beam steering is obtained by implementing rotational phase shifting via manipulating the liquid metal in the slots. X-band unit cell prototypes are fabricated on glass substrate carrying a patterned metal film, and the slot channels are formed by Polydimethylsiloxane (PDMS) using soft lithography techniques.

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