Speech spectrum non-stationarity detection based on line spectrum frequencies and related applications

Ankara : Department of Electrical and Electronics Engineering and The Institute of Engineering and Sciences of Bilkent University, 1998.Thesis (Master's) -- Bilkent University, 1998.Includes bibliographical references leaves 124-132In this thesis, two new speech variation measures for speech spectrum nonstationarity detection are proposed. These measures are based on the Line Spectrum Frequencies (LSF) and the spectral values at the LSF locations. They are formulated to be subjectively meaningful, mathematically tractable, and also have low computational complexity property. In order to demonstrate the usefulness of the non-stationarity detector, two applications are presented: The first application is an implicit speech segmentation system which detects non-stationary regions in speech signal and obtains the boundaries of the speech segments. The other application is a Variable Bit-Rate Mixed Excitation Linear Predictive (VBR-MELP) vocoder utilizing a novel voice activity detector to detect silent regions in the speech. This voice activity detector is designed to be robust to non-stationary background noise and provides efficient coding of silent sections and unvoiced utterances to decrease the bit-rate. Simulation results are also presented.Ertan, Ali ErdemM.S

Pitch-synchronous processing of speech signal for improving the quality of low bit rate speech coders

Ph.D.Committee Chair: Thomas P. Barnwel

Türkiye’de kişilerarası sosyal güven ve bireysel belirleyicileri

Kişilerarası sosyal güvenin ekonomik gelişme, düşük suç oranı gibi pek çok olumlu toplumsal durum ile ilişkisi literatürde kabul görmüş durumdadır. Bu nedenle Türkiye’de çok düşük düzeyde olan kişilerarası sosyal güvenin mikro düzeyde belirleyicilerini anlamak oldukça önemlidir. 2015 yılı sonunda Türkiye’nin seçmen yaşındaki nüfusunu temsil niteliğine sahip bir örneklem verilerine dayanarak yaptığımız analizde elde ettiğimiz bulgular kurumlara güvenin ve politik etkinlik algısının daha yüksek kişilerarası sosyal güvene sahip bireylerin özelliklerinden olduğunu göstermektedir. Bu sonuç, daha iyi işleyen ve daha duyarlı bir siyasi sistemin toplumdaki kişilerarası güvene katkıda bulunacağını göstermektedirPublisher's Versio

Classification of Human Motion Using Radar Micro-Doppler Signatures with Hidden Markov Models

One of the desirable features in a ground surveillance radar is to provide information about what a detected person is doing. This would give a law enforcement organization ability to detect suspicious activities remotely and act accordingly. Previously, micro-Doppler radar signatures from humans were shown to have the necessary features to make that distinction. Typically, micro-Doppler signal spectrograms are used to obtain features to classify what the person is doing. However, most of these techniques treat the spectrogram as an image, and obtain features through some image processing techniques. In this work, we propose the use of hidden Markov models as an alternative method to statistically model both instantaneous and correlated long-term variations within the micro-Doppler signal to classify a motion. In addition, we propose use of principle component analysis (PCA) as a data driven feature extraction approach that captures vital statistics of the input at a much reduced dimension. Experiments show that with the proposed methods, perfect classification of four different motions can be attained when training and testing set both contains data from same people, and 90% accuracy is obtained when training and testing set has data from different people

Efficiency enhancement in photoelectrochemical water splitting: defect passivation and boosted charge transfer kinetics of zinc oxide nanostructures via chalcopyrite/chalcogenide mix sensitization

ZnO thin films in nanorod (NR) and nanoflower (NF) morphologies were used as photoelectrode scaffolds for efficient visible-light-driven photoelectrochemical (PEC) water splitting process, where their decoration with copper indium gallium sulfide (CIGS) and indium sulfide (In2S3) layers resulted in significant PEC performance enhancement. ZnO NF/CIGS/In2S3 photoelectrodes exhibited a remarkably high PEC efficiency (∼6.0% applied bias photon-to-current efficiency, 83% incident photon-to-current efficiency) due to the negligible dark current, while ZnO NR/CIGS/In2S3 generated a photocurrent density of 30.0mA.cm-2 at 0.4 V (vs Ag/AgCl), being one of the highest performances reported in the literature for copper-based chalcopyrite photoelectrodes so far. The interfacial photoelectrode-electrolyte charge transport dynamics, investigated via intensity-modulated photocurrent spectroscopy, exhibited a sevenfold increase in charge transfer efficiencies with a significant drop in surface recombination kinetics for ZnO NF after CIGS/In2S3 decoration. The obtained results show consistency with numerically modeled electric field distribution profiles and electron paramagnetic resonance results of ZnO NF, rationalizing the enhanced charge transfer rates for decorated samples and confirming the defect passivating nature of CIGS/In2S3

Refugee children with beta-thalassemia in Turkey: Overview of demographic, socioeconomic, and medical characteristics

Aim Since the beginning of the Syrian civil war, more than 3.5 million Syrians have been under temporary protection status in Turkey. Because beta-thalassemia (BT) is a prevalent disorder in the Mediterranean countries, we decided to estimate the prevalence of and make an overview of the demographic, socioeconomic, medical characteristics, and healthcare problems of refugee children with BT. Patients Eighteen Turkish Pediatric Hematology Oncology Centers (PHOC) with 318 refugee children from 235 families participated in the study. The mean age of the patients was 8.1 +/- 4.8 years (0.5-21 years). The mean time after immigration to Turkey was 2.5 +/- 1.5 years (range, 0.1-7 years). Seventy-two (22.6%) of them were born and diagnosed with BT in Turkey. On physical examination, 82 patients (26%) were underweight and 121 patients (38%) were stunted. The appearance of a thalassemic face was reported for 207 patients (65.1%). Hepatomegaly and splenomegaly were reported in 217 (68.2%) and 168 (52.8%) patients, respectively. The median ferritin level was 2508 ng/mL (range, 17-21 000 ng/mL) at the first admission, and 2841 ng/mL (range, 26-12 981 ng/mL) at the last visit after two years of follow-up in a PHOC (P > 0.05). The most frequently encountered mutation was IVSI-110 (G>A) (31%). Before immigration, only 177 patients (55.6%) reported the use of chelators; after immigration it increased to 268 (84.3%). Conclusion Difficulties in communication, finding a competent translator capable in medical terminology, nonregular use of medications, and insensitivity to prenatal diagnosis were preliminary problems. The current extent of migration poses emerging socioeconomic and humanitarian challenges for refugee patients with BT