Browsing by Subject "Data acquisition"
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Item Open Access Algorithms for within-cluster searches using inverted files(Springer, 2006-11) Altıngövde, İsmail Şengör; Can, Fazlı; Ulusoy, ÖzgürInformation retrieval over clustered document collections has two successive stages: first identifying the best-clusters and then the best-documents in these clusters that are most similar to the user query. In this paper, we assume that an inverted file over the entire document collection is used for the latter stage. We propose and evaluate algorithms for within-cluster searches, i.e., to integrate the best-clusters with the best-documents to obtain the final output including the highest ranked documents only from the best-clusters. Our experiments on a TREC collection including 210,158 documents with several query sets show that an appropriately selected integration algorithm based on the query length and system resources can significantly improve the query evaluation efficiency. © Springer-Verlag Berlin Heidelberg 2006.Item Open Access Analysis of the nonconcentric radome-enclosed cylindrical reflector antenna system, e-polarization case(Taylor & Francis, 2005) Oğuzer, T.; Altintas, A.Two-dimensional (2-D) radiation of a directive complex line source is analyzed in the presence of a perfectly conducting (PEC) reflector antenna system and nonconcentrically located dielectric radome. Similar problem was studied in the literature by using method of regularization and Green's function formulation for the H-polarization case. Here the same techniques are used for E-polarization case but in this case the scattered part of the Green's function is computed by using an FFT based algorithm. This provides us to solve the larger geometries accurately in reasonable computer times. So this approach can be considered as another alternative for the analysis of the E-polarized radome-enclosed reflector antenna system. Various numerical results are presented to support the convergence and accuracy of the technique and at the same time these results can be considered as reference data.Item Open Access Classification of closed and open shell pistachio nuts using principal component analysis of impact acoustics(IEEE, 2004-05) Çetin, A. Enis; Pearson, T. C.; Tewfik, A. H.An algorithm was developed to separate pistachio nuts with closed-shells from those with open-shells. It was observed that upon impact on a steel plate, nuts with closed-shells emit different sounds than nuts with open-shells. Two feature vectors extracted from the sound signals were melcepstrum coefficients and eigenvalues obtained from the principle component analysis of the autocorrelation matrix of the signals. Classification of a sound signal was done by linearly combining feature vectors from both mel-cepstrum and PCA feature vectors. An important property of the algorithm is that it is easily trainable. During the training phase, sounds of the nuts with closed-shells and open-shells were used to obtain a representative vector of each class. The accuracy of closed-shell nuts was more than 99% on the test set.Item Open Access Computer vision based method for real-time fire and flame detection(Elsevier BV, 2006-01-01) Töreyin, B. U.; Dedeoǧlu, Y.; Güdükbay, Uğur; Çetin, A. EnisThis paper proposes a novel method to detect fire and/or flames in real-time by processing the video data generated by an ordinary camera monitoring a scene. In addition to ordinary motion and color clues, flame and fire flicker is detected by analyzing the video in the wavelet domain. Quasi-periodic behavior in flame boundaries is detected by performing temporal wavelet transform. Color variations in flame regions are detected by computing the spatial wavelet transform of moving fire-colored regions. Another clue used in the fire detection algorithm is the irregularity of the boundary of the fire-colored region. All of the above clues are combined to reach a final decision. Experimental results show that the proposed method is very successful in detecting fire and/or flames. In addition, it drastically reduces the false alarms issued to ordinary fire-colored moving objects as compared to the methods using only motion and color clues. © 2005 Elsevier B.V. All rights reserved.Item Open Access Computer vision based text and equation editor for LATEX(IEEE, 2004-06) Öksüz, Özcan; Güdükbay, Uğur; Çetin, EnisIn this paper, we present a computer vision based text and equation editor for LATEX. The user writes text and equations on paper and a camera attached to a computer records actions of the user. In particular, positions of the pen-tip in consecutive image frames are detected. Next, directional and positional information about characters are calculated using these positions. Then, this information is used for on-line character classification. After characters and symbols are found, corresponding LATEX code is generated.Item Open Access Computer-controlled characterization of high-voltage, high-frequency SiC devices?(IEEE, 2006) Ortiz-Rodriguez, J. M.; Hefner, A. R.; Berning, D.; Hood, C.; Ölçüm, SelimA software-based high-voltage curve tracer application for SiC device characterization is presented. This flexible application interface is developed to define testing parameters needed to control the hardware of a custom-made 25 kV-capable SiC characterization test bed. Data acquisition is controlled for optimum resolution, and I-V characterization is computed by means of a user-defined time interval based on the shape of the applied power pulses. Both voltage and current waveforms are displayed for each data point captured to allow the user to observe transient effects. Additionally, the software allows archiving some or all of these transient waveforms. Acquired results are shown to demonstrate functionality and flexibility of the new system.Item Open Access Coupled matrix pencil method for frequency extrapolation of electromagnetic solutions(IEEE, 2005) Yıldırım, Ferhat; Gürel, LeventMatrix pencil method (MPM) is used to extrapolate the available electromagnetic solutions in frequency domain to estimate the high-frequency solutions. A new approach, namely, coupled MPM, is introduced to obtain the electromagnetic solutions at intermediate frequencies using the available low-frequency and high-frequency data.Item Open Access Differentiated ABR: a new architecture for flow control and service differentiation in optical burst switched networks(IEEE, 2005) Akar, Nail; Boyraz, HakanIn this paper, we study a new control plane protocol, called Differentiated ABR (D-ABR), for flow control and service differentiation in optical burst switched networks. Using D-ABR, we show using simulations that the optical network can be designed to work at any desired burst blocking probability by the flow control service of the proposed architecture. This architecture requires certain modifications to the existing control plane mechanisms as well as incorporation of certain scheduling mechanisms at the ingress nodes; however we do not make any specific assumptions on the data plane for the optical core nodes. Moreover, with this protocol, it is possible to almost perfectly isolate high priority and low priority traffic throughout the optical network as in the strict priority-based service differentiation in electronically switched networks.Item Open Access A distributed and dynamic data gathering protocol for sensor networks(IEEE, 2007-05) Tan, Hüseyin Özgür; Körpeoğlu, İbrahim; Stojmenović, I.In this paper we propose a distributed, self organizing, robust and energy efficient data gathering algorithm for sensor networks operating in environments where all the sensor nodes are not in direct communication range of each other and data aggregation is used while routing. Proposed algorithm is based on local minimum spanning tree (LMST) structure, which nodes can construct from the position of their 1-hop neighbors. Reporting tree is constructed from the sink by allowing only edges of LMST to join the tree, plus possibly some direct links to the sink. Each node selects as parent the LMST neighbor so that the total energy cost of route to the sink is minimal. We also describe route maintenance protocols to respond to predicted sensor failures and addition of new sensors. Our simulation results show that our algorithm prolongs the network lifetime significantly compared to some alternative schemes. © 2007 IEEE.Item Open Access Extraction of primary and secondary frequency control from active power generation data of power plants(Elsevier Ltd, 2015) Ozer, B.; Arıkan, Orhan; Moral, G.; Altintas, A.Frequency control is a vital component of a secure and robust power grid and it ought to be closely monitored. Frequency control consists of two main components; primary and secondary control and their contributions are usually aggregated in the active power generation data of a plant, which is acquired via Supervisory Control And Data Acquisition. In many cases, such as in Turkey, they are demanded to be evaluated separately due to different impacts on power system or different financial policies. However, this is not usually a straightforward process since primary and secondary response cannot be obtained distinctly. In this work, Extraction of Primary and Secondary Control (EPSCon) algorithm is introduced to extract primary and secondary response over active power generation data. Based on time and frequency domain characteristics of primary and secondary response, EPSCon is developed on a Expectation-Maximization type recursive scheme employing Generalized Cross Correlation and ℓ1 Trend Filtering techniques. Favorably, EPSCon uses a simple plant model built upon basic governor and plant load controller technical characteristics as an initial estimate of primary and secondary response.Item Open Access First large-scale information retrieval experiments on Turkish texts(ACM, 2006-08) Can, Fazlı; Koçberber, Seyit; Balcık, Erman; Kaynak, Cihan; Öcalan, H. Çağdaş; Vursavaş, Onur M.We present the results of the first large-scale Turkish information retrieval experiments performed on a TREC-like test collection. The test bed, which has been created for this study, contains 95.5 million words, 408,305 documents, 72 ad hoc queries and has a size of about 800MB. All documents come from the Turkish newspaper Milliyet. We implement and apply simple to sophisticated stemmers and various query-document matching fonctions and show that truncating words at a prefix length of 5 creates an effective retrieval environment in Turkish. However, a lemmatizer-based stemmer provides significantly better effectiveness over a variety of matching functions.Item Open Access Inflation and inflation uncertainty in the G-7 countries(Elsevier BV, 2005) Berument, Hakan; Dincer, N. N.This study examines the relationship between inflation and inflation uncertainty in the G-7 countries for the period from 1957 to 2001. The causality between the inflation and inflation uncertainty is tested by using the Full Information Maximum Likelihood Method with extended lags. Our results suggest that inflation causes inflation uncertainty for all the G-7 countries, while inflation uncertainty causes inflation for Canada, France, Japan, the UK and the US. Furthermore, we find that in four countries (Canada, France, the UK and the US) increased uncertainty lowers inflation, and in only one country (Japan), increased uncertainty raises inflation. © 2004 Elsevier B.V. All rights reserved.Item Open Access Location and curvature estimation of spherical targets using multiple sonar time-of-flight measurements(Institute of Electrical and Electronics Engineers, 1999-12) Barshan, B.A novel, flexible, three-dimensional multisensor sonar system is described to localize the center of a generalized spherical target and estimate its radius of curvature. Point, line, and planar targets are included as limiting cases which are important for the characterization of a mobile robot's environment. Sensitivity analysis of the curvature estimate with respect to measurement errors and some of the system parameters is provided. The analysis is verified experimentally for specularly reflecting cylindrical and planar targets. Typical accuracies in range and azimuth are 0.17 mm and 0.1°, respectively. Accuracy of the curvature estimate depends on the target type and system parameters such as transducer separation and operating range.Item Open Access Modeling and feedback control for subsonic cavity flows: a collaborative approach(IEEE, 2005) Yan, P.; Debiasi, M.; Yuan, X.; Caraballo, E.; Serrani, A.; Özbay, Hitay; Myatt, J. M.; Samimy, M.Feedback control of aerodynamic flows is attracting the attention of researchers from a wide spectrum of specialties, because of its interdisciplinary nature and the challenges inherent to the problem. One of the main goals of the Collaborative Center of Control Science at The Ohio State University is to bring together researchers from different disciplines to advance the science and technology of flow control. This paper presents a comprehensive summary of the effort of the Center on modeling and feedback control of subsonic cavity-flow resonance. In particular, we give a detailed description of the experimental apparatus, including the wind tunnel testbed, the data measurement and acquisition system, and the real time control system. Reduced-order models of the flow dynamics based on physically-oriented linear models and Proper Orthogonal Decomposition are introduced and their effectiveness for control system design discussed. Finally, results obtained with experimental and model-based controller design are discussed.Item Open Access Protein folding rates correlate with heterogeneity of folding mechanism(American Physical Society, 2004) Öztop, B.; Ejtehadi, M. R.; Plotkin, S. S.The folding rates of protein were shown to correlate with the degree of heterogeneity in the formation of native contacts. It was shown that both experimental rates and simulated free energy barriers for 2-state proteins depend on the degree of heterogeneity present in the folding process. Heterogeneity due to variance in the distribution of native loop lengths, and variance in the distribution of φ values, were observed to increase folding rates and reduce folding barriers. The observed effect due to φ variance was found to be the most statistically significant, because φ variance captures both heterogeneity arising from native topology and that arising from energetics.Item Open Access Seizure detection using least eeg channels by deep convolutional neural network(Institute of Electrical and Electronics Engineers Inc., 2019) Avcu, Mustafa Talha; Zhang, Z.; Chan, D. W. S.This work aims to develop an end-to-end solution for seizure onset detection. We design the SeizNet, a Convolutional Neural Network for seizure detection. To compare SeizNet with traditional machine learning approach, a baseline classifier is implemented using spectrum band power features with Support Vector Machines (BPsvm). We explore the possibility to use the least number of channels for accurate seizure detection by evaluating SeizNet and BPsvm approaches using all channels and two channels settings respectively. EEG Data is acquired from 29 pediatric patients admitted to KK Woman's and Children's Hospital who were diagnosed as typical absence seizures. We conduct leave-one-out cross validation for all subjects. Using full channel data, BPsvm yields a sensitivity of 86.6% and 0.84 false alarm (per hour) while SeizNet yields overall sensitivity of 95.8 % with 0.17 false alarm. More interestingly, two channels seizNet outperforms full channel BPsvm with a sensitivity of 93.3% and 0.58 false alarm. We further investigate interpretability of SeizNet by decoding the filters learned along convolutional layers. Seizure-like characteristics can be clearly observed in the filters from third and forth convolutional layers.Item Open Access A synthetic aperture imaging system using surface wave modes(IEEE, 1995) Bozkurt, Ayhan; Arıkan, Orhan; Atalar, AbdullahA synthetic aperture acoustic imaging system with a novel inversion algorithm is described. Data is obtained by using a transducer insonifying the sample surface at a critical angle which is excited by a short electrical pulse. The critical angle is chosen for a suitable surface wave or Lamb wave mode that exists on the object. The transducer is mechanically scanned in only one direction during which many pulse excitations and subsequent recordings are realized. The received signal is sampled in time and digitized to be processed by using the new inversion approach providing an optimal 2-D image of the surface reflectivity.Item Open Access Vision-based single-stroke character recognition for wearable computing(IEEE, 2001) Özer, Ö. F.; Özün, O.; Tüzel, C. Ö.; Atalay, V.; Çetin, A. EnisParticularly when compared to traditional tools such as a keyboard or mouse, wearable computing data entry tools offer increased mobility and flexibility. Such tools include touch screens, hand gesture and facial expression recognition, speech recognition, and key systems. We describe a new approach for recognizing characters drawn by hand gestures or by a pointer on a user's forearm captured by a digital camera. We draw each character as a single, isolated stroke using a Graffiti-like alphabet. Our algorithm enables effective and quick character recognition. The resulting character recognition system has potential for application in mobile communication and computing devices such as phones, laptop computers, handheld computers and personal data assistants.Item Open Access Wide-band maximum likelihood direction finding by using tree-structured EM algorithm(IEEE, 1996) Çadallı, Nail; Arıkan, OrhanA tree structured Expectation Maximization (EM) algorithm is proposed and applied to the wide-band angle of arrival estimation. It may be seen as a generalization on EM using the ideas of Cascade EM algorithm and Space Alternating Generalized EM algorithm. Also, for passive data acquisition, robust and efficient alternatives for the estimation of the source signals are investigated.