Novel solutions to classical signal processing problems in optimization framework

Cataloged from PDF version of article.Novel approaches for three classical signal processing problems in optimization framework are proposed to provide further flexibility and performance improvement. In the first part, a new technique, which uses Hermite-Gaussian (HG) functions, is developed for analysis of signals, whose components have non-overlapping compact time-frequency supports. Once the support of each signal component is properly transformed, HG functions provide optimal representations. Conducted experiments show that proposed method provides reliable identification and extraction of signal components even under severe noise cases. In the second part, three different approaches are proposed for designing a set of orthogonal pulse shapes for ultra-wideband communication systems with wideband antennas. Each pulse shape is modelled as a linear combination of time shifted and scaled HG functions. By solving the constructed optimization problems, high energy pulse shapes, which maintain orthogonality at the receiver with desired timefrequency characteristics are obtained. Moreover, by showing that, derivatives of HG functions can be represented as a linear combination of HGs, a simple optimal correlating receiver structure is proposed. In the third part, two different methods for phase-only control of array antennas based on semidefinite modelling are proposed. First, antenna pattern design problem is formulated as a non-convex quadratically constraint quadratic problem (QCQP). Then, by relaxing the QCQP formulation, a convex semidefinite problem (SDP) is obtained. For moderate size arrays, a novel iterative rank refinement algorithm is proposed to achieve a rank-1 solution for the obtained SDP, which is the solution to the original QCQP formulation. For large arrays an alternating direction method of multipliers (ADMM) based solution is developed. Conducted experiments show that both methods provide effective phase settings, which generate beam patterns under highly flexible constraints.Alp, Yaşar KemalPh.D

A NOVEL METHOD FOR SIGNAL COMPONENT INCISION IN THE TIME-FREQUENCY PLANE

Zaman-frekans düzleminde örtüşmeyen, tıkız bileşenlere sahip sinyallerin bileşenlerini tespit eden ve ayrıştıran yeni bir zaman-frekans sinyal analizi tekniği geliştirilmiştir. Geliştirilen tekniğin oldukça yüksek gürültü seviyelerinde bile sinyallerin ayrıştırılmasında başarılı olduğu gözlemlenmiştir. Önerilen teknik, 1) Sinyal bileşenlerinin tespiti, 2) Tespit edilen bileşenlerin anlık frekanslarının kestirimi, 3) Zaman-frekans düzleminde filtreleme basamaklarından oluşmaktadır. Bu kuram, döngüsel olup, her bir döngüde bir sinyal bileşeni tespit edilip ayrıştırılmaktadır. Ölçüm sinyalindeki bileşenlerin tespiti ve anlık frekans kestirimi için, zaman-frekans dağılımları kullanılmıştır. Anlık frekans kestirimi, gürültüye karşı hassasiyeti oldukça gürbüz olan, ana eğri izdüşümleri ile elde edilmiştir. Zaman-frekans düzleminde filitreleme frekans bükme ile sağlanmıştır. Önerilen tekniğin başarımı sentetik sinyaller üzerinde çeşitli gürültü seviyelerinde incelenmiştir.A new time-frequency signal analysis technique for detection and extraction of signal components, which have non-overlapping compact support in the time-frequency plane, is developed. Proposed technique is observed to be successful even under high noise levels. The method is composed of three main steps: 1)detection of signal components, 2)estimation of instantaneous frequencies of the detected components 3) filtering in the time-frequency plane. By construction, it is an iterative algorithm which detects and extracts one component at a time. Time-frequency distributions are utilized for signal component detection and instantaneous frequency estimation. Principle curve projections, which is very robust to noise, is used for instantaneous frequency estimation. Filtering in the time-frequency plane is accomplished by frequency warping. The performance of the proposed algorithm is analyzed on synthetic data sets for different noise levels

Machine-based classification of ADHD and nonADHD participants using time/frequency features of event-related neuroelectric activity

Karakaş, Sirel (Dogus Author) -- Doğutepe, Elvin (Dogus Author)Objective: Attention-deficit/hyperactivity disorder (ADHD) is the most frequent diagnosis among children who are referred to psychiatry departments. Although ADHD was discovered at the beginning of the 20th century, its diagnosis is still confronted with many problems.& para;& para;Method: A novel classification approach that discriminates ADHD and nonADHD groups over the time-frequency domain features of event-related potential (ERP) recordings that are taken during Stroop task is presented. Time-Frequency Hermite-Atomizer (TFHA) technique is used for the extraction of high resolution time-frequency domain features that are highly localized in time-frequency domain. Based on an extensive investigation, Support Vector Machine-Recursive Feature Elimination (SVM-RFE) was used to obtain the best discriminating features.& para;& para;Results: When the best three features were used, the classification accuracy for the training dataset reached 98%, and the use of five features further improved the accuracy to 99.5%. The accuracy was 100% for the testing dataset. Based on extensive experiments, the delta band emerged as the most contributing frequency band and statistical parameters emerged as the most contributing feature group.& para;& para;Conclusion: The classification performance of this study suggests that TFHA can be employed as an auxiliary component of the diagnostic and prognostic procedures for ADHD.& para;& para;Significance: The features obtained in this study can potentially contribute to the neuroelectrical understanding and clinical diagnosis of ADHD

Machine-based learning system: classification of ADHD and non-ADHD participants

Karakaş, Sirel (Dogus Author) -- Doğutepe, Elvin (Dogus Author) -- Conference full title : 25th Signal Processing and Communications Applications Conference (SIU); 15 May 2017 through 18 May 2017. Antalya; TurkeyDikkat Eksikliği ve Hiperaktivite Bozukluğu (DEHB), psikiyatri servislerine başvuran çocuklarda en çok rastlanan rahatsızlıktır. Bu bozukluk 20. Yüzyılın başında tanımlanmasına rağmen, teşhisinde halen ciddi sorunlar yaşanmaktadır. Bu çalışmada, Olaya ilişkin Potansiyel (OİP) verilerinden çıkarılan zaman frekans özellikleri kullanılarak DEHB olan çocukların bu bozukluğu taşımayanlara göre sınıflandırılması elde edilmiştir. Bu özniteliklerin DEHB teşhisinde en etkili olanları Destek Vektör Makinesi – Yinelemeli Öznitelik Seçimi yöntemiyle belirlenmiş ve bu özniteliklerle eğitilen Destek Vektör Makinesi, üç öznitelik kullanıldığında %98 ve altı öznitelik kullanıldığında %99.5 doğrulukla DEHB teşhisi koymayı başarmıştır. Sonuçlar Tekrarlanan Çapraz Geçerlilik Yöntemiyle elde edilmiştir. Ayrıca, bu yöntem Kararlılık Seçimi ile desteklenerek DEHB tanısında en etkili öznitelikler belirlenmiştir. Ayrıca yeni bir tasarımla önerilen düzenek test edilmiş ve % 100 doğruluk elde edilmiştir. Sonuçlar, çalışmadaki düzeneğin psikiyatrik bozuklukların tanısında ve seyrinde kullanılabileceğini göstermektedir.Attention-deficit/hyperactivity disorder (ADHD) is the most frequent diagnosis among children who are referred to psychiatry departments. Although ADHD was discovered at the beginning of the 20th century, its diagnosis is confronted with many problems. In this paper, a novel classification approach that discriminates ADHD and non-ADHD groups over the timefrequency domain features of ERP recordings is presented. Support Vector Machine-Recursive Feature Elimination (SVMRFE) was used to obtain best discriminating features. When only three of these features were used the accuracy of classification reached to 98%, and use of six features further improved classification accuracy to 99.5%. The proposed scheme was tested with a new experimental setup and 100% accuracy is obtained. The results were obtained using RCV. The classification performance of this study suggests that TFHA can be employed as a core component of the diagnostic and prognostic procedures of various psychiatric illnesses

Compressive digital receiver: First performance measurements

In this work, sensitivity, instantaneous dynamic range and bandwidth measurement results of the Compressive Digital Receiver (CDR) implemented on a real hardware, will be reported for the first time. Developed CDR is a compressive sensing based sub-Nyquist sampling receiver which can monitor 2.25GHz bandwith instantaneously by using four ADC's each of which is sampling at 250MHz and has 14 bits resolution. It is observed that the sensitivity and dynamic range of the CDR changes with respect to frequency. For 2.25GHz bandwidth, the best and worst sensitivity values of the CDR are reported as -62dBm and -41dBm, respectively. Single-signal dynamic range of CDR is measured as at least 60dB for the whole band. The best and worst values of the two-signal dynamic rage values are observed as 45dB and 20dB, respectively. Bu çalışmada, ilk defa bir donanım üzerinde gerçeklenen SATSAÇ (Sıkıştırılmış Algılama Tabanlı Sayısal Almaç) sisteminin performansını tanımlayan duyarlılık, anlık dinamik alan ve bant genişliğine dair ölçüm sonuçları paylaşılacaktır. Geliştirilen SATSAÇ sistemi, her biri 250MHz ile örnekleme yapan 14 bit çözünürlükte dört adet ADC (Analog to Digital Converter) ile Nyquist limiti altında örnekleme yaparak en az 2.25GHz’lik bir bandı, sıkıştırılmış algılama teknikleri ile anlık olarak gözlemleyebilmektedir. Yapılan ölçümlerde, SATSAÇ sisteminin duyarlılık ve dinamik alan değerlerinin frekans bandına göre değişiklik gösterdiği gözlemlenmiştir. 2.25GHz’lik bant boyunca, en iyi duyarlılık seviyesi -62dBm, en kötü duyarlılık seviyesi -41dBm olarak ölçülmüştür. Tüm bant boyunca tek-sinyal dinamik alan en az 60dB olarak ölçülmüş olup, iki-sinyal dinamik alan en iyi 45dB, en kötü 20dB olarak gözlemlenmiştir

Erkek ratlarda renal iskemi-reperfüzyon hasarına karşı elajik asitin koruyucu etkisi

The aim of this study was to evaluate the possible protective effect of ellagic acid (EA) on rats following renal ischemia–reperfusion (I/R) injury. Twenty-four Wistar rats were divided into three groups. Sham group underwent laparotomy then waited for 45 min without ischemia. I/R group were subjected to left renal ischemia for 45 minutes followed by 60 min of reperfusion. I/R+EA group were subjected to the same renal ischemia/reperfusion as the I/R group, were also given 85 mg/kg EA perorally 30 min prior to the ischemia. Malondialdehyde (MDA), total antioxidant capacity (TAC), total oxidant status (TOS), and oxidative stress index (OSI) were determined on the blood samples and kidney tissues. Histopathological analyses were conducted on the kidney tissues. I/R damage significantly increased serum MDA levels in the I/R group when compared with Sham group. Serum TAC level was significantly lower in I/R group than I/R+EA group. A significantly increase on OSI levels and decrease on TAC levels was found in the kidneys in I/R group. In I/R + EA group, EA reversed the negative effects of I/R injury. EA pretreatment.Bu çalışmanın amacı ratlarda renal iskemi-reperfüzyon (I/R) hasarına karşı elajik asitin (EA) olası koruyucu etkisini değerlendirmektir. Yirmi dört erkek Wistar rat; Sham, I/R ve I/R+EA olmak üzere üç gruba ayrıldı. Sham grubuna laparotomi yapıldı ve iskemi uygulanmaksızın 45 dakika bekletildi. I/R grubuna 45 dakikalık sol renal iskemiyi takiben 60 dakikalık reperfüzyon uygulandı. I/R+EA grubuna da I/R grubundakilere benzer şekilde iskemi/reperfüzyon prosedürü uygulandı, fakat iskemiden 30 dakika önce ratlara 85 mg/kg EA ağızdan verildi. Kanda ve böbrek dokusunda malondialdehit (MDA), total antioksidan kapasite (TAC), total oksidan statusu (TOS) ve oksidatif stres indeksi (OSI) bakıldı. Böbrek dokusu histopatolojik yönden incelendi. Sham grubu ile kıyaslandığında I/R grubunda serum MDA düzeyi anlamlı derecede yüksek idi. Ayrıca I/R+EA grubu ile kıyaslandığında I/R grubunda serum TAC düzeyi anlamlı derecede düşük bulundu. I/R grubunda böbrek dokusunda OSI düzeyi yüksek TAC düzeyi düşük bulunurken, I/R+EA grubunda iskemi ile oluşan etkilerin EA ile düzeldiği görüldü. EA verilmesinin tubuler nekroz skorunu azaltmada etkili olduğu bulundu. Çalışmanın sonucuna göre; EA, renal I/R hasarı sonrası meydana gelen oksidatif hasarı ve oluşan histopatolojik değişiklikleri iyileştirmektedir