Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu
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Article Citation Count: Hadi Hadı, Ali Sameer; Gazi, O. (2021). "The Research and Design of Multi Relays in Cooperative Communication System Based on Polar Codes", Cankaya University Journal of Science and Engineering, Vol.18, No.2, pp.117-124.The Research and Design of Multi Relays in Cooperative Communication System Based on Polar Codes(2021) Hadi Hadı, Ali Sameer; Gazi, Orhan; 102896In this paper, we propose a method to increase the performance of cooperative communication using polar codes. For this purpose, we consider non-line-of sight (NLOS) cooperative communication scheme where destination node does not receive signal from source directly. The relay nodes use decodes and forward approach. We propose a voting scheme for the relay nodes, which share information among them. It is shown by the simulation results that the proposed approach significantly improves the performance of relayed communication.Article Citation Count: Gazi, Orhan. (2012). "Prunable collision free random interleaver design", Wireless Personal Communication, Vol.65, No.3, pp.555-566.Prunable collision free random interleaver design(2012) Gazi, OrhanIn this article we introduce a new collision free prunable random interleaver. The suggested interleaver is a joint structure involving rectangular and S-random interleaver. It comprises a general model for all kind of collision free prunable random interleavers. In addition, it can be designed for any number of parallel processors and any length of information sequence vector and can be considered also as a template for collision free prunable interleavers. The proposed interleaver can be used with all kind of turbo-like codes. The performance of the proposed interleaver is measured with parallel decodable serially concatenated convolutional codes (PDSCCCs) and compared to the PDSCCCs' performance with collision full S-random interleaver.Article Citation Count: Altay Arpali, Serap. (2021). "Performance Analysis Of Optical Spherical Wave İn Biological Tissue", Mugla Journal of Science and Technology, Vol.7, No.2, pp.36-39.Performance Analysis Of Optical Spherical Wave İn Biological Tissue(2021) Altay Arpali, Serap; 51304In this study, bit error rate (BER) of optical spherical wave is investigated to analyze the performance of spherical wave through in soft tissue. Within this scope, average BERs () of optical spherical wave are extensively examined depends on the different tissue and turbulence parameters that are random changes in the refractive index of the soft tissue, the tissue length from source to receiver, and the outer scale of the tissue turbulence. It is observed from the outputs that the () increases with increasing value of outer scales, tissue lengths and random changes in the refractive index of the soft tissue. Also we investigated () values of the optical spherical wave for the different values of the one half of the quantified slope in the range of power-law scaling. It is found that smaller s of the spherical wave are obtained for decreasing values of one half of the quantified slope in the range of power-law scaling.Article Citation Count: Yalçın, Uğur; Umul, Yusuf Ziya. (2005). "Odak Dışı Beslemeli Silindirik Parabolik Reflektör Antenlere Ait Işıma İntegralinin Optimizasyonu", Uludağ Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi, Vol.10, No.2.Odak Dışı Beslemeli Silindirik Parabolik Reflektör Antenlere Ait Işıma İntegralinin Optimizasyonu(2005) Yalçın, Uğur; Umul, Yusuf ZiyaBu çalışmada, ( , ,z ρ 0 φ0 ) koordinatlarına yerleştirilmiş çizgisel akım kaynağıyla beslenen, z eksenine paralel sonsuz uzun mükemmel iletken içbükey silindirik parabolik reflektör antenden saçılma problemi göz önüne alınmıştır. İlk olarak, Hertz vektörüne ait yüzey ışıma integrali Fiziksel Optik (FO) yöntemi kullanılarak belirlenmiştir. Bu integral ifadesin de görülen Green fonksiyonu tanımlanmış ve yüzeye ait normal birim vektörü ile yüzeye gelen toplam magnetik alan bileşeninin vektörel çarpımı elde edilmiştir. Daha sonra bu ifadeler ışıma integralinde yerine yazılmış ve integralin ' z katı hesaplanmıştır. Neticede, FO ışıma integrali sadece ' φ katına bağlı olarak ifade edilebilmiştir. Elde edilen integral ifadesinden faydalanılarak anten sistemine ait ışıma diyagramları, ilgili parametrelerin çeşitli değerleri için polar koordinatlarda çizdirilmiş ve böyle bir anten sisteminin tasarımı için en optimum durum araştırılmıştır. Çalışmada silindirik parabolik reflektör antenin çalışma frekansı 2 (GHz) olarak seçilmiştirArticle Citation Count: Arpalı, Çağlar (2019). "Spatial Generation of Gauss Beam Array for Photonic Applications", Karaelmas Fen ve Mühendislik Dergisi, Vol.9, No.2, pp.201-205.Spatial Generation of Gauss Beam Array for Photonic Applications(2019) Arpalı, Çağlar; 20809In this paper, an alternative experimental method has been proposed in relevant to the generation of Gauss beam array. For this purpose,the light beams have been modeled based on the diffraction of a plane wave by an array of Gaussian apertures and implemented accordingly. Spatial generation of the Gauss beam array has experimentally been performed by the use of Spatial Light Modulator (SLM). The produced light beams have been recorded by a Charge Couple Device (CCD) detector with a large field of view and the profile evaluations of monitored beams are done. Moreover, theoretical calculations have been verified with empirical observations. With this proposed new beam shaping method, it can make it possible to generate and control the Gauss beam array in real-time for many high throughput photonic applications such as optical communications and biophotonics.Article Citation Count: Bingöl, Hilal; Çankaya, Erkam; Schmıdt, Klaus W. (2016). "Eyleyici doyumu altında dizi kararlı kooperatif otomatik seyir kontrolü", Pamukkale Üniversitesi Mühendislik Bilimleri Dergisi, Vol.22, No.8, pp.636-642.Eyleyici doyumu altında dizi kararlı kooperatif otomatik seyir kontrolü(2016) Bingöl, Hilal; Çankaya, Erkam; Schmıdt, Klaus Werner; 218795Kooperatif otomatik seyir kontrolü (CACC), araçtan araca haberleşme yöntemiyle veri iletilmesini ve uzaklık ölçümlerine göre yoğun trafikte güvenilir araç takibinin yapılmasını sağlar. Kullanılan CACC dizaynları dizi kararlılığının temel özelliklerini sorunsuz bir şekilde yerine getirirken doğrusal araç modelleri için sınırlıdır. Bu makalede ise, doğrusal olmayan araç modeli kullanıldığında ve lider araca uygulanan giriş sinyali doyuma uğramadığında dizi kararlılığının korunabildiği gösterilmiştir.Book Citation Count: Gazi, Orhan. Dijital Mantık Devrelerinin Tasarımı, Ankara: Seçkin Yayıncılık, pp. 1-392, 2018.Dijital Mantık Devrelerinin Tasarımı(Seçkin Yayıncılık, 2018) Gazi, OrhanConference Object Citation Count: Ali AL_Isawi, Ahmed Sami; Gazi, Orhan. "The Performance of Turbo Equalization Using Blind and Non-blind Channel Estimation Technique", URSI-TÜRKİYE'2014 VII. Bilimsel Kongresi, 28-30 Ağustos 2014, Elazığ.The Performance of Turbo Equalization Using Blind and Non-blind Channel Estimation Technique(2014) Ali AL_Isawi, Ahmed Sami; Gazi, OrhanThis article presents, we measure the performance of turbo equalizers under channel estimation .Channel estimation is performed via two different approaches, one is based on the use of training sequences ,and the other on the other hand is a blind estimation technique .We have used per-survivor approach for the blind channel estimation . From the simulation results we see that per survivor based approach performs as well as training sequence based approachArticle Citation Count: Beldek, Ulaş; Leblebicioğlu, Kemal (2006). "Strategy creation, decomposition and distribution in particle navigation", Information Sciences, Vol. 177, pp. 755-770.Strategy creation, decomposition and distribution in particle navigation(Elsevier, 2006) Beldek, Ulaş; Leblebicioğlu, Kemal; 59950Strategy planning is crucial to control a group to achieve a number of tasks in a closed area full of obstacles. In this study, genetic programming has been used to evolve rule-based hierarchical structures to move the particles in a grid region to accomplish navigation tasks. Communications operations such as receiving and sending commands between particles are also provided to develop improved strategies. In order to produce more capable strategies, a task decomposition procedure is proposed. In addition, a conflict module is constructed to handle the challenging situations and conflicts such as blockage of a particle’s pathway to destination by other particles.Article Citation Count: Şentürk, Hakan; Çil, Celal Zaim; Sağıroğlu, Şeref (2016). "Siber Güvenlik Yatırım Kararları Üzerine Literatür İncelemesi", Politeknik Dergisi, Vol. 19, No. 1, pp. 39-51.Siber Güvenlik Yatırım Kararları Üzerine Literatür İncelemesi(2016) Şentürk, Hakan; Çil, Celal Zaim; Sağıroğlu, ŞerefKarmaşıklığı ve sıklığı her geçen gün artan siber saldırıların yol açtığı yüksek ekonomik zararlar ile bu saldırılara karşı korumasağlayan çok sayıda siber güvenlik teknolojisi ürünlerinin yatırım alternatifi olarak sunulduğu güvenlik sektörü, alanda yapılançalışmaların odak noktasını siber güvenliğin ekonomik boyutuna yöneltmiştir. Kısıtlı kaynak şartları altında siber güvenlikyatırım kararlarının verilebilmesine yönelik kullanılabilecek yöntemlerin belirlenmesi ihtiyacı öne çıkmıştır.Bu çalışmada siber güvenlik yatırım kararlarının verilmesi sürecinde uygulanabilecek yatırım stratejileri, siber güvenlikrisklerinin belirlenmesi ve ölçülmesi, güvenlik saldırılarının maliyet ve etkisinin ölçülmesi, güvenlik teknolojilerinin etkinliğininölçülmesi ve güvenlik yatırımlarının en uygun seviyesinin belirlenmesi olmak üzere beş kategoride alanda son onbeş yıldayapılan akademik çalışmalar incelenmiş, literatürdeki boşluklar ortaya konularak sonraki araştırmalara yön verilmesiamaçlanmıştır.Article Citation Count: Günay, Osman; Töreyin, Behçer Uğur; Çetin, Ahmet Enis (2011). "Online adaptive decision fusion framework based on projections onto convex sets with application to wildfire detection in video", Optical Engineering, Vol. 50, No. 2.Online adaptive decision fusion framework based on projections onto convex sets with application to wildfire detection in video(2011) Günay, Osman; Töreyin, Behçer Uğur; Çetin, Ahmet Enis; 19325t. In this paper, an online adaptive decision fusion framework is developed for image analysis and computer vision applications. In this framework, it is assumed that the compound algorithm consists of several sub-algorithms, each of which yields its own decision as a real number centered around zero, representing the confidence level of that particular sub-algorithm. Decision values are linearly combined with weights that are updated online according to an active fusion method based on performing orthogonal projections onto convex sets describing sub-algorithms. It is assumed that there is an oracle, who is usually a human operator, providing feedback to the decision fusion method. A video-based wildfire detection system is developed to evaluate the performance of the algorithm in handling the problems where data arrives sequentially. In this case, the oracle is the security guard of the forest lookout tower verifying the decision of the combined algorithm. Simulation results are presented.Article Citation Count: Genç, Fatih, Gazi O. (2021). "Fast Calculation of Polar Code Bits and Frozen-Bit Locations", Çankaya University Journal of Science and Engineering, Vol.18, No.2, pp.125-132.Fast Calculation of Polar Code Bits and Frozen-Bit Locations(2021) Genç, Fatih; Gazi, OrhanIn this paper, we show that encoding operation for the polar codes can be achieved without the employment of the generator matrix, and all the polar code bits can be generated at the same time using a number of tree-encoding structures running in parallel. Since encoding matrix is not used in the implementation of the polar encoders in digital electronic devices, hardware space is saved, and low complexity hardware applications are achieved. Besides, we also proposed a method for the calculation of split channel parameters, such as Bhattacharyya bounds or average-bit-error probabilities of the transmitted bits using a tree-based structure. Moreover, the proposed structure enables to calculate the probability of bit-error values of all the transmitted bits at the same time in a parallel manner and decide the locations of data and frozen bits very rapidly.Article Citation Count: Özaydın, Selma. (2023). "Investigation of factors affecting noise robustness in voice activity detectors", Journal of the Faculty of Engineering and Architecture of Gazi University, Vol.38, No.1, pp.497-508.Investigation of factors affecting noise robustness in voice activity detectors(2023) Özaydın, Selma; 253019In this manuscript, some voice activity detectors (VADs) in the literature were examined in terms of factors affecting their robustness under different acoustic noise conditions and in this context, the changes in detection accuracy rates according to changing noise conditions were tested. In this scope, the effect of situations such as whether the threshold value used in the decision phase in VAD methods is fixed or adaptive, the analysis window is short or long, the use of more than one feature vector together has been evaluated and analyzed comparatively. While three of the four different VAD detectors examined in this manuscript use feature vectors within the short-term analysis window while generating the decision result, one decides according to the measurement result of long-term spectral vectors. The VAD detectors in the article have been tested using the NOIZEUS noisy speech database. Thus, the performance of the analyzed VADs has been evaluated under different acoustic conditions using an extensive database that has already taken place in the literature. During the testing of the analyzed VADs, different input noise speech signals with environmental background noises between [15-0dB] such as restaurant, car, street, or station were tested. Tests were carried out using objective test measurement methods and the detection accuracy rate of each VAD method was measured. The results showed that each method gave different endurance performance in adverse environmental conditions.Conference Object Citation Count: Gazi, Orhan. "New Upper Bounds for the Computation of Complementary Error Function", 2012.New Upper Bounds for the Computation of Complementary Error Function(2012) Gazi, OrhanIn this article we provide tighter upper bounds for complementary error function which is a monotonically decreasing function widely used in communication theory. The provided bounds approach the exact value in the limiting case. The derivation of the bounds are based on the monotonically increasing property of exponential function used in complementary error function.Conference Object Citation Count: Yurttaş, Hüseyin Galip..et al. "LED’lerin Spektrofotometride Kullanımı", 2011.LED’lerin Spektrofotometride Kullanımı(2011) Yurttaş, Hüseyin Galip; Özdumanlar, Sercan; Cambaz Büke, Göknur; Çil, Celal Zaim; Kamışlı, Özcan; Ertuğ, A. MithatIşık yayan diyotların (Light Emitting Diode-LED) ışık yayma modunda verici olduğu, fotodiyot veya güneş pili modunda alıcı olduğu bir düzenek oluşturularak LED’lerin çeşitli ışık şiddetleri altında ürettikleri fotoakım değerleri ölçülmüştür. Bu fotoakım değerleri verici ve alıcı LED’lerin yaydıkları ve hassas oldukları dalgaboylarına ve ışık şiddetlerine göre karşılaştırılmıştır. Bu çalışmada yapılan ölçümler değerlendirildiğinde, LED’lerin düşük maliyetli spektrometrelerde ve spektrofotometri uygulamalarında kullanılabileceği gösterilmiştir.Conference Object Citation Count: Çil, Celal Zaim. "Işık Yayan Diyotlar (LED’LER) ve Aydınlatmada Kullanımı", LED_Konferans, 2014.Işık Yayan Diyotlar (LED’LER) ve Aydınlatmada Kullanımı(2014) Çil, Celal ZaimLED’ler ışık saçan yarı-iletken p-n diyotlardır. Bir p-n ekleminde iletim yönünde akım geçtiği zaman elektronlar ve delikler p ve n yarı-iletkenin birleştiği eklem bölgesinde birbiri ile karşılaşır ve birleşirler. Aslında bu birleşme kristal içinde serbest hareket eden yüksek enerjili bir elektronun, yarı-iletken malzeme içine katkılanmış ve sabit olarak kristal yapıya bağlı ve son yörüngesinde bir elektron eksik olan iyonun bu son yörüngesindeki boşluğu doldurması olayıdır. Serbest durumdan bağlı duruma geçen elektronun kaybettiği enerji yarı-iletken malzemeye ya ısı olarak veya ışık olarak verilir. Isı enerjisi yerine ışık enerjisi yani foton oluşması için p-n malzemenin direkt enerji bant geçişli bir malzeme olması gerekir. İlk ışık yayan diyotlar çok küçük yoğunlukta ve düşük enerjili fotonlar yayabilen (kızılötesi ve kırmızı renkte ışık) diyotlardı. Bunlar daha çok ikaz ve işaret verici olarak kullanılıyordu. Zamanla sarı renkli ve son dönemlerde ise yarı iletken alaşımlı malzemeler (GaN) kullanılarak mavi renkli ışık yayabilen LED’ler geliştirildi. Mavi ışık oluşturan yüksek enerjili fotonların fosforu uyarması ile tıpkı floresan lambalarda olduğu şekilde beyaz ışık elde edildi. İkinci bir yol olarak da yeşil, kırmızı ve mavi ışığı karıştırarak beyaz ışık elde edilebildi. Beyaz ışık yayan LED’lerin yaydığı ışığın gücünün artırılabilmesi bu LED’lerin aydınlatmada kullanılabilmesini mümkün hale getirdi. Akkor, halojen ve floresan lambaya karşı birçok üstünlüğü olan LED’li ışık kaynakları bunlara rakip olarak üretilmeye başlandı. Yarı iletkenlerden ışığın elde edilerek aydınlatma uygulamalarında kullanılan bu lambalara Yarı İletken Aydınlatma (solid state lighting-SSL) ismi verilmektedir. LED’li lambalar günümüzde giderek artan oranda aydınlatmada, sinyalizasyonda, haberleşmede, otomotiv aydınlatmasında kullanılmaktadır. Bir LED’li lamba şu bileşenlerden oluşur : Işığı oluşturan bir p-n diyot, ışığı istenilen şekilde yönlendiren optik sistemler, diyoda uygun miktarda iletim akımını veren bir elektronik güç kaynağı (sürücü), yüksek sayıda foton üreten ve bu nedenle ısınan diyodu soğutan bir soğutucu, bütün bu parçaları bir arada tutan bir mekanik gövde. Bir LED’li lambanın verimliliğini sadece ışığı oluşturan p-n diyot belirlemez. Sürücü devrenin ve soğutucu sistemlerin de lambanın tasarımında çok önemli yeri vardır. Bunların da uygun tasarlanması halinde LED’li lambanın ömrü uzun ve kendisi verimli olur. Bu bildiride bir LED’li lambanın oluşturulmasında önemli bir yer tutan alt sistemler incelenmekte ve özellikle sürücü devrelerinin tasarımı üzerinde durulmaktadır.Article Citation Count: Büyükkata M.; Özdoğan, C.; Güvenç, Z.B. (2008). "Hydrogen hosting of nano scale boron clusters", Romanian Journal of Information Science and Technology, Vol.11, No.1, pp.59-70.Hydrogen hosting of nano scale boron clusters(2008) Büyükata, M.; Özdoğan, C.; Güvenç, Z.B.In this paper the Density Functional Results of hydrogen bonded boron micro clusters with B3LYP/6-311++G(d,p) level of computations will be presented. Energetics and structural stability with their possible stable geome- tries of various selected micro complexes of BmHn (for m and n<11) boron hydrides have been analysed, and their binding energies with HOMO-LUMO energy gaps have been determined. Mainly, e®ects of the number of hydrogen atoms on the structures of the boranes are assessed. Moreover, for the cage con̄gurations their distortions have been investigated for the neutral, anionic and cationic cases. It has been observed that there have been two opposing factors for the cage con̄gurations. One of which is the \peeling' of the cage structures by the hydrogen atoms, and the other one is reforming a smaller cage form simultaneously with the remaining boron atoms inside. This is observed mostly for the odd values of m. From our studies it has been also observed that with the bare boron clusters alone, it is di±cult to increase the capacity of the hydrogen storage. Therefore, further studies are necessary with the boron complexes.Conference Object Citation Count: A. K. Gözcü, U. Turan, E. G. Schmidt and K. Schmidt. “Dinamik Dağitik Gerçek Zamanli Endüstriyel İletişim Protokolu (D2GEP) Gerçekleştirimi / The implementation of Dynamic Distributed Real time Industrial communication Protocol (D2RIP) ,” IEEE 20. Sinyal İşleme ve İletişim Uygulamaları Kurultayı, 2012.Dinamik Dağıtık Gerçek Zamanlı Endüstriyel İletişim Protokolü (d2gep) Gerçekleştirimi(2012) Gözcü, A. K.; Turan, U.; Schmidt, E. G.; Schmidt, K.Article Citation Count: Alrataim, Abdelkareim; Gazi, Orhan. (2020). "High Performance Low Latency Parallel Successive Cancelation Decoder Structures for Polar Codes", Çankaya University Journal of Science and Engineering, Vol.17, No.2, pp.128-136.High Performance Low Latency Parallel Successive Cancelation Decoder Structures for Polar Codes(2020) Alrataim, Abdelkareim; Gazi, OrhanPolar codes are decoded using successive cancellation (SC) algorithm where likelihood ratios (LRs) for data bits are calculated in a sequential manner, and decisions are made using the calculated LRs. During the decoding of an information bit, the decision results for the predecessor bits are used, and a wrongly decided predecessor bit has negative effect on the accurate calculation of the LR for the information bit being decoded. In SC algorithm, when LR=1, the information bit is decoded as u ̂_i=0, however, such a decision has 50% of chance of being correct. In this paper, we propose improved polar decoders utilizing a number of SC decoders. We consider the case of LR=1, and propose polar decoder structures for the more accurate calculation of the LRs of the successor bitsConference Object Citation Count: Umul, Yusuf Ziya; Yengel, Emre; Aydın, Ayhan. "Comparison of physical optics integral and exact solutions for cylinder problem", Proceedings of ELECO, 2003.Comparison of physical optics integral and exact solutions for cylinder problem(2003) Umul, Yusuf Ziya; Yengel, Emre; Aydın, AyhanThe sound source composition of the urban sound environment varies depending on the geography and socio-cultural context. Current sound taxonomies in the literature categorize urban sound sources by their source types (e.g., human-made, natural, electromechanical) and respective semantic attributes. This study aims to add another taxonomical layer to the existing urban sound source categorization methods. The additional layer is a recently proposed sound source classification framework (CLIC). The CLIC framework identifies sound sources based on their Diegesis and Intention parametric attributes. The former parametric attribute, diegesis, was derived from film sound design. The geographical and socio-cultural context of the built environment can be considered as its narrative; hence, every event that happens within the functional context can be called diegetic, while the events that do not belong to that specific place can be called nondiegetic. The latter parametric attribute, intention, was derived from product design. One of the prominent sound source categorization methods in product sound design is to group the product emitted sounds as consequential and intentional. Combining these two parametric attributes with the existing taxonomies, the CLIC framework outputs a place-specific design guideline, clearly dictating the actions a sound designer should take. The two parametric attributes group the sound sources under four distinct areas, which dictates the degree of influence of designers on the specific sound source. The four zones are defined as the creation zone, limitation zone, isolation zone, and control zone. Each zone dictates step-by-step sound design instructions for the sound designer. This study consists of two main phases: field recordings and web-based listening tests. The sound sources present in the urban sound environment were identified in the field recordings phase. Later, in the web-based listening tests phase, the identified sound sources were evaluated based on the CLIC framework, and hence, their respective zones on the model were identified. The outcomes of the study propose clear step-by-step design guidelines and present action suggestions for environmental sound designers.
