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Öğe A Novel Voice Activity Detection for Multi-Channel Noise Reduction(Ieee-Inst Electrical Electronics Engineers Inc, 2021) Çolak, Ramazan; Akdeniz, RafetIn this study, a voice activity detection technique is designed using features such as short-term energy, periodicity and spectral flatness. The desired results are obtained by using these three features, even at low signal to noise ratio values. In addition, performance of multi-channel noise reduction algorithms such as Wiener speech distortion weighted, spatial prediction, minimum variance distortion-less response are compared using the proposed voice activity detection. Two different audio signals and three different noise types are used in the experiment. Noisy speech and only detection of noisy areas have been performed by proposed voice activity detection algorithm. The filter coefficients have been calculated for each filter algorithm used after detection of noisy speech and only noisy areas. The calculated filter coefficients have been multiplied by the frequency components of the signal received from the reference microphone to obtain an enhanced signal. Segmental signal to noise ratio, an objective method, and mean opinion score as a subjective method have been used to evaluate the performance of the filters. Speech distortion weighted Wiener filter has been found to be the best filter for noise reduction performance.Öğe A study of selvedge waste length in rapier weaving by image analysis technique(Ege Univ, 2017) Akdeniz, Rafet; Özek, Hikmet Ziya; Durusoy, GöktekinOne of the most important constraints of shutleless weaving machines is the necessity to form a false selvedge at both sides. The nature of selvedge formation in a rapier loom is analysed, and the variation in the length of weft yarn waste is measured by image analysis technique. The behaviour of weft yarn gripper at the entry into and exit from the shed are analysed by a high speed camera. The length of the trailing end of weft yarn is manually measured and digital image analysis technique is also used for the measurements. High speed film images are processed to measure the waste length of the weft and also the gap between the edge of the fabric and auxiliary warp yarns. An Image processing software is used for 2D measuring by sub pixel edge detection on the subsequent still image frames of high speed film. The measurements by image processing are found to be very close to the actual values, and it proves to be advantageous especially in case of stretch weft yarns.Öğe Analysis of QoE key factors in IPTV systems: Channel switching(2011) Malkoş, S.; Uçar, Erdem; Akdeniz, RafetThe usage of Internet Protocol TV (IPTV) deployments in the consumer electronics market is growing very popularly in recent years. In IPTV systems, Quality of Experience (QoE) is very critical factor for end-user satisfaction. Existing and future IPTV systems will offer a large number of channels to users. The most important factors that affects to QoE in IPTV systems are channel zapping and channel selection problems. Generally, the channel zapping time depends on several parameters like Internet Group Membership Protocol (IGMP) command processing time, network delay time, IPTV consumer device processing delay time, jitter buffer delay time, MPEG decoder time and Conditional Access/Digital Rights Management (CA/DRM) delay time. In this paper, we present an analysis of channel change delay in IPTV systems and we propose a new approach based on channel-based peer selection, called CBPS where the most suitable peer to construct peer-to-peer (P2P) communication will be discovered from a look-up table in the central server. © 2011 IEEE.Öğe Call Admission Control Jointly with Resource Reservation in Cellular Wireless Networks(Springeropen, 2010) Bozkurt, Aytül; Akdeniz, Rafet; Uçar, ErdemTo efficiently utilize the total resources and to serve mobile users demanding for different types of service, system resource utilization of these services should be considered, and efficient resource management techniques should be developed. In this paper, we propose a new call admission control (CAC) scheme jointly with resource management by considering the two service types: prioritized calls and nonprioritized calls. Proposed scheme limits the new and handoff prioritized and non-prioritized call arrivals according to call-level quality of service (QoS) requirements. By searching algorithm, admission parameters are obtained optimally and required QoS are guaranteed. Due to high priority of the prioritized calls, the admittance of non-prioritized calls into channel is restricted, while prioritized calls are admitted as long as there is sufficient bandwidth. To evaluate the performance of the proposed CAC scheme, we have compared the numerical results from the analytical model with those of New Call Bounding scheme. It is shown that the proposed CAC scheme uses the resources effectively and improves all the upper-bound QoS requirements with respect to the New Call Bounding scheme for prioritized and non-prioritized users.Öğe Call Admission Control Policy for Integration of Voice/Data Traffic in Cellular Mobile Networks(IEEE Computer Soc, 2010) Bozkurt, Aytül; Uçar, Erdem; Akdeniz, RafetIn integrated voice/data cellular mobile networks, the most important consideration is to utilize the resources in an efficient way and maintain the required quality of service (QoS). In this paper, we proposed a new call admission control scheme for improving efficiency of resource utilization. Proposed scheme restricts the new and handoff voice and data calls arrived to system by finding the optimal threshold number of new and handoff voice and data calls allowed in system according to admission criters such as maximum data response time, voice and data blocking and dropping probabilities. From the numerical analysis, we observed that required call-level QoS for both voice and data calls is provided and upper bound of data response time is guaranteed to data calls. Also taking the required minimum bandwith need of voice calls in different values, we evaluated the performance improvements of data calls.Öğe KABLOSUZ AĞLARDA KAYNAK YÖNETİMİ(Trakya Üniversitesi, 2009) Bozkurt, Aytül; Uçar, Erdem; Akdeniz, RafetBu çalışmada, çokluservis kablosuz ağlarda, servis kalitesi sağlamak için etkili radyo kaynak yönetim tekniklerinden arama izin şemaları incelenmiştir. Yeni nesil kablosuz ağlar (3G, 4G) daha fazla sayıda kullanıcıyı ve multimedya servislerini destekleyecektir. Artan kullanıcı ve multimedya servisi ihtiyacı ile birlikte servis kalitesinden ödün vermeden kısıtlı kaynakları en verimli biçimde kullanabilmek için, etkili radyo kaynak yönetimine gereksinim duyulur, bu gereksinim için farklı arama izin şemaları ve bu şemaların değerlendirilmesinde Markov zinciri modeli incelenmiştirÖğe Performance analysis for resource management in integrated cellular/WLAN networks(2010) Bozkurt, A.; Uçar, Erdem; Akdeniz, RafetTo utilize the total resources in cellular/WLAN integration for both cellular and WLAN network, their different channel allocation strategies should be considered and efficient resource management techniques are required. In this paper, we proposed a new call admission scheme to utilize the coupled resources effectively. Proposed scheme, by taking the different resource sharing strategies of both network, limits the new, horizontal and vertical handoff voice and data call arrivals together with call-level QoS requirements. In cellular network, all admission parameters are obtained by searching algorithm. In WLAN, due to preemptive priority of voice calls, the access of data calls into channel is restricted while voice calls are admitted as long as there is sufficient bandwidth. From the numerical analysis, it is shown that integrated network uses the resources effectively and provides the all upper bound QoS requirements to voice and data users. © 2010 IEEE.Öğe QoS and channel allocation in integrated voice/data cellular wireless networks(2010) Bozkurt, A.; Akdeniz, Rafet; Uçar, ErdemIn this work, Call Admission Control Schemes which is one of the efficient resource management techniques are analyzed and proposed a new call admission scheme by using the structure of data allowing available bandwidth allocation over Complete-Partitioning Sharing technique. Voice calls are real-time services and needs fixed bandwidth, on the other hand, data calls are non-real time services and adaptable to work in available bandwidth without a concession made for Quest. It is obtained state-dependent service rates by means of this structure of data and modeled two-dimensional(2-D) Markov Chain to be able to measure performance of the proposed scheme and calculated mathematically performance measurements that is voice/data blocking/dropping probabilities for each state over this model Numerical results show that proposed scheme guaranteed the targeted QoS parameters levels in resource utilization. ©2010 IEEE.Öğe Resource Allocation for Integrated Voice and Data Services in Cellular/WLAN Networks(China Inst Communications, 2011) Bozkurt, A.; Uçar, Erdem; Akdeniz, RafetWireless Local Area Network (WLAN) with high data bit rates can be used with cellular network to achieve higher level of Quality of Service (QoS) by sharing their total resources efficiently. The integration between cellular and WLAN networks should be ensured considering different channel-allocation strategies of both networks and efficient resource management techniques should be developed. In this paper, we propose a new call admission scheme to use the coupled resource effectively. The proposed scheme, by taking the different resource sharing strategies for two access networks, limits the new, horizontal and vertical handoff voice and data call arrivals with respect to their call-level QoS requirements. Numerical results show that the proposed integrated cellular/WLAN network model uses the resources more effectively and achieves all upper bound QoS requirements for voice and data users as compared with the non-integrated network model.Öğe Ses Sinyalinde Gürültü Saptama İçin Özgün Bir Yaklaşım(Namık Kemal Üniversitesi, 2018) Çolak, Ramazan; Akdeniz, RafetSes etkinliği algılama, genelde konuşma tanıma, konuşma sıkıştırma gibi konuşma işleme süreçlerinin başında kullanılan bir uygulamadır. Konuşma sesinin olup olmadığını tespit etmede kullanılır ve buna göre uygulamanın devamına yön verir. Sesin varlığını tespit etmede kullanılan belli başlı özellikler vardır. Kullanılan özelliklerin fazla olması algoritmanın verimliliği ile doğrudan ilişkilidir. Klasik VAD algoritmaları genelde STE kullanılarak oluşturulduğundan, düşük sinyal gürültü oranı değerlerinde çok hassastır, bu yüzden istenilen sonuçları veremeyebilir. Çözümde kullanılan özellikler için gerçek zamanlı sesler kullanarak sesli bölge ve gürültülü bölge ayırt edilmeye çalışılmıştır. Bu çalışmada sesin varlığını tespit etmek için STE, periyodiklik ve Spektral düzlük gibi üç özellik kullanılmıştır, kullanılan bu üç özellik ile düşük SNR değerlerinde de istenilen sonuçlar elde edilmiştir. Bu yöntemin, özellikle düşük SNR değerlerinde klasik metotlara göre daha iyi performans elde ettiği gözlemlenmiştir.Öğe Speech Coding System for Total Laryngectomees(IEEE, 2014) Oktay, M. Oytun; Akdeniz, RafetThis work aims to obtain a signal processing method to neutralize the mechanical vibration sound from the electrolarynx which is used as a supporting device for speech restoration of people who have gone under resection operation over their larynxs due to various reasons. After the main problem of electrolarynx which is a noninvasive solution to the speech production problem arised due to the resection of the larynx and it's effect on the speech signal were introduced, approaches to minimize this problem in a single input system and their performances are compared.Öğe The Visualization of Solutions to Electromagnetic Field Problems by Using Matlab(Tekirdağ Namık Kemal Üniversitesi, 2021) Alisoy, Hafiz; Akdeniz, Rafet; Özbey, NecatiIn this study, we use the superposition principle to find a particular solution to Poisson and Laplace equations. It is assumed that the field in a homogeneous dielectric is excited by space charges under a specific density distribution. Under these assumptions, the results of visualization to electrostatic field solutions are reported for two cases: i) calculation of the electrostatic field between two shielded cables and ii) calculation of the electrostatic field between the dielectric corner and a parallel long charged conductor. In this study, we aim to initiate a discussion of the use of computer analysis and modeling as an educational tool for engineering students.
