Publications without Fulltext
Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
Browse
292 results
Filters
Advanced Search
Filter by
Settings
Search Results
Publication Metadata only Performance measures for video object segmentation and tracking(IEEE-Inst Electrical Electronics Engineers Inc, 2004) Erdem, Çiğdem Eroğlu; Sankur, Bülent; Department of Electrical and Electronics Engineering; Tekalp, Ahmet Murat; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 26207We propose measures to evaluate quantitatively the performance of video object segmentation and tracking methods without ground-truth (GT) segmentation maps. The proposed measures are based on spatial differences of color and motion along the boundary of the estimated video object plane and temporal differences between the color histogram of the current object plane and its predecessors. They can be used to localize (spatially and/or temporally) regions where segmentation results are good or bad; and/or they can be combined to yield a single numerical measure to indicate the goodness of the boundary segmentation and tracking results over a sequence. The validity of the proposed performance measures without GT have been demonstrated by canonical correlation analysis with another set of measures with GT on a set of sequences (where GT information is available). Experimental results are presented to evaluate the segmentation maps obtained from various sequences using different segmentation approaches.Publication Metadata only Exploring projection based mixed reality with tangibles for nonsymbolic preschool math education(Assoc Computing Machinery, 2019) N/A; N/A; Department of Psychology; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Salman, Elif; Beşevli, Ceylan; Göksun, Tilbe; Özcan, Oğuzhan; Ürey, Hakan; Master Student; Researcher; Faculty Member; Faculty Member; Faculty Member; Department of Psychology; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Engineering; N/A; N/A; 47278; 12532; 8579A child's early math development can stem from interactions with the physical world. Accordingly, current tangible interaction studies focus on preschool children's formal (symbolic) mathematics, i.e. number knowledge. However, recent developmental studies stress the importance of nonsymbolic number representation in math learning, i.e. understanding quantity relations without counting(more/less). To our knowledge, there are no tangible systems based on this math concept. We developed an initial tangible based mixed-reality(MR) setup with a small tabletop projector and depth camera. Our goal was observing children's interaction with the setup to guide our further design process towards developing nonsymbolic math trainings. In this paper we present our observations from sessions with four 3-to-5 year old children and discuss their meaning for future work. Initial clues show that our MR setup leads to exploratory and mindful interactions, which might be generalizable to other tangible MR systems for child education and could inspire interaction design studies.Publication Metadata only Robust speech recognition using adaptively denoised wavelet coefficients(IEEE, 2004) Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; N/A; Tekalp, Ahmet Murat; Erzin, Engin; Akyol, Emrah; Faculty Member; Faculty Member; Master Student; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; 26207; 34503; N/AThe existence of additive noise affects the performance of speech recognition in real environments. We propose a new set of feature vectors for robust speech recognition using denoised wavelet coefficients. The use of wavelet coefficients in speech processing is motivated by the ability of the wavelet transform to capture both time and frequency information and the non-stationary behaviour of speech signals. We use one set of noisy data, such as data with car noise, and we use hard thresholding in the best basis for denoising. We use isolated digits as our database in our HMM based speech recognition system. A performance comparison of hard thresholding denoised wavelet coefficients and MFCC feature vectors is presented.Publication Metadata only Multimodal analysis of speech prosody and upper body gestures using hidden semi-Markov models(Institute of Electrical and Electronics Engineers (IEEE), 2013) N/A; N/A; N/A; Department of Computer Engineering; Department of Computer Engineering; Bozkurt, Elif; Asta, Shahriar; Özkul, Serkan; Yemez, Yücel; Erzin, Engin; PhD Student; PhD Student; Master Student; Faculty Member; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; 107907; 34503Gesticulation is an essential component of face-to-face communication, and it contributes significantly to the natural and affective perception of human-to-human communication. In this work we investigate a new multimodal analysis framework to model relationships between intonational and gesture phrases using the hidden semi-Markov models (HSMMs). The HSMM framework effectively associates longer duration gesture phrases to shorter duration prosody clusters, while maintaining realistic gesture phrase duration statistics. We evaluate the multimodal analysis framework by generating speech prosody driven gesture animation, and employing both subjective and objective metrics.Publication Metadata only Optical modulation with silicon microspheres(IEEE-Inst Electrical Electronics Engineers Inc, 2009) Gürlü, Oğuzhan; N/A; Department of Physics; Yüce, Emre; Serpengüzel, Ali; Master Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; 245435; 27855In this letter, a silicon microsphere coupled to a silica optical fiber half coupler has been characterized for electrooptical modulation in the L-band at 1.55 mu m. Electrooptical modulation of the transmitted and the 90 degrees elastic scattered signals for both the TE and the TM polarizations of the microsphere resonances has been observed.Publication Metadata only Investigation of the ultrafast response and saturable absorption of voltage-controlled graphene(Optica Publishing Group (formerly OSA), 2018) Kakenov N.; Kocabas C.; N/A; N/A; Department of Physics; Toker, Işınsu Baylam; Çizmeciyan, Melisa Natali; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Department of Physics; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851Ultrafast pump-probe measurements show that at a bias voltage of 1V, voltage reconfigurable graphene supercapacitors can operate as fast saturable absorbers with adjustable insertion loss over an ultrabroad spectral range from 630 to 1100 nm.Publication Metadata only SecVLC: secure visible light communication for military vehicular networks(Association for Computing Machinery (ACM), 2016) Tsonev, Dobroslav; Burchardt, Harald; N/A; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Uçar, Seyhan; Ergen, Sinem Çöleri; Özkasap, Öznur; PhD Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 7211; 113507Technology coined as the vehicular ad hoc network (VANET) is harmonizing with Intelligent Transportation System (ITS) and Intelligent Traffic System (ITF). An application sce- nario of VANET is the military communication where ve- hicles move as a convoy on roadways, requiring secure and reliable communication. However, utilization of radio fre- quency (RF) communication in VANET limits its usage in military applications, due to the scarce frequency band and its vulnerability to security attacks. Visible Light Communi- cation (VLC) has been recently introduced as a more secure alternative, limiting the reception of neighboring nodes with its directional transmission. However, secure vehicular VLC that ensures confidential data transfer among the participat- ing vehicles, is an open problem. In this paper, we propose a secure military light communication protocol (SecVLC) for enabling efficient and secure data sharing. We use the directionality property of VLC to ensure that only target vehicles participate in the communication. Vehicles use full- duplex communication where infra-red (IR) is utilized to share a secret key and VLC is used to receive encrypted data. We experimentally demonstrate the suitability of SecVLC in outdoor scenarios at varying inter-vehicular distances with key metrics of interest, including the security, data packet delivery ratio and delay.Publication Metadata only Ruby microsphere and liquid cyrstal based tunable optical filter(Ieee, 2009) Beccherelli, Romeo; Department of Physics; N/A; N/A; Serpengüzel, Ali; Murib, Mohammed Sharif; Hüseyinoğlu, Ersin; Faculty Member; PhD Student; Master Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 27855; N/AA microsphere placed in a liquid crystal is used as an optical filter. By changing the refractive index of the liquid cyrstal, the resonance frequency of the sphere is controlled.Publication Metadata only Optimal rate and input format control for content and context adaptive video streaming(IEEE, 2004) Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; N/A; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; Özçelebi, Tanır; Faculty Member; Faculty Member; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; 26207; 16372; N/AA novel dynamic programming based technique for optimal selection of input video format and compression rate for video streaming based on "relevancy" of the content and user context is presented. The technique uses context dependent content analysis to divide the input video into temporal segments. User selected relevance levels assigned to these segments are used in formulating a constrained optimization problem, which is solved using dynamic programming. The technique minimizes a weighted distortion measure and the initial waiting time for continuous playback under maximum acceptable distortion constraints. Spatial resolution and frame rate of input video and the DCT quantization parameters are used as optimization variables. The technique is applied to encoding of soccer videos using an H.264 [1] encoder. The improvements obtained over a standard H.264 implementation are demonstrated by experimental results.Publication Metadata only Artificial bandwidth extension of speech excitation(IEEE, 2015) Department of Computer Engineering; N/A; Erzin, Engin; Turan, Mehmet Ali Tuğtekin; Faculty Member; PhD Student; Department of Computer Engineering; College of Engineering; Graduate School of Sciences and Engineering; 34503; N/AIn this paper, a new approach that extends narrowband excitation signals to synthesize wide-band speech have been proposed. Bandwidth extension problem is analyzed using source-filter separation framework where a speech signal is decomposed into two independent components. For spectral envelope extension, our former work based on hidden Markov model have been used. For excitation signal extension, the proposed method moves the spectrum based on correlation analysis where the distance between the harmonics and the structure of the excitation signal are preserved in high-bands. In experimental studies, we also apply two other well-known extension techniques for excitation signals comparatively and evaluate the overall performance of proposed system using the PESQ metric. Our findings indicate that the proposed extension method outperforms other two techniques. © 2015 IEEE./ Öz: Bu çalışmada dar bantlı kaynak sinyallerinin bant genişliği artırılarak geniş bantlı konuşma sentezleyen yeni bir yaklaşım önerilmektedir. Bant genişletme problemi kaynak süzgeç analizinin yardımıyla iki bağımsız bileşen üzerinde ayrı ayrı ele alınmıştır. Süzgeç yapısını şekillendiren izgesel zarfı, saklı Markov modeli tabanlı geçmiş çalışmamızı kullanarak iyileştirirken, dar bantlı kaynak sinyalinin genişletilmesi için izgesel kopyalamaya dayalı yeni bir yöntem öneriyoruz. Bu yeni yöntemde dar bantlı kaynak sinyalinin yüksek frekans bileşenlerindeki harmonik yapısını, ilinti analizi ile genişletip geniş bantlı kaynak sinyali sentezlemekteyiz. Öne sürülen bu iyileştirmenin başarımını ölçebilmek için literatürde sıklıkla kullanılan iki ayrı genişletme yöntemi de karşılaştırmalı olarak degerlendirilmekte- dir. Deneysel çalışmalarda öne sürdüğümüz genişletmenin PESQ ölçütüyle nesnel başarımı gösterilmiştir.