Mühendislik ve Doğa Bilimleri Fakültesi

Permanent URI for this communityhttps://gcris.khas.edu.tr/handle/20.500.12469/36

Browse

Now showing 1 - 20 of 61

Citation Count: 0
"2-pirazolin yapısındaki yeni bir bileşiğin sentezi, moleküler modellemesi ve monoaminoksidaz inhibitörü etkisinin araştırılması"
(Türkiye Halk Sağlığı Kurumu, 2018) Yelekçi, Kemal; Uçar, Gülberk; Yelekçi, Kemal
Amaç: Nöromediatörlerin yıkımından sorumlu olan monoamin oksidaz (MAO) enziminin izoformlarının (MAO-A ve -B) birçok hastalık ile yakından ilişkili olduğu; MAO inhibitörlerinin depresyon, Parkinson ve Alzheimer hastalığı gibi hastalıkların tedavisinde kullanıldığı bilinmektedir. Grubumuzca daha etkin, tersinir ve az yan etkili yeni bir MAO inhibitörü (SH2U bileşiği) sentezlenmiş ve bu bileşiğin insan MAO enzimini (hMAO) inhibe etme yeteneği incelenmiştir. Ayrıca bu yeni bileşiğin hMAO ile etkileşimi, moleküler modelleme çalışmaları ile detaylı bir şekilde araştırılmıştır. Sentezlenen yeni bileşiğin hMAO’yu kuvvetli bir şekilde yarışmalı ve tersinir olarak inhibe ettiği bulunmuştur. Söz konusu bileşiğin Parkinson ve Alzheimer hastalıklarının tedavisinde ümit verici bir ilaç etken maddesi olabileceği düşünülmektedir. Yöntem: 3’,5’-Dikloro-2’-hidroksi asetofenon ile p-tolualdehit’in metanol içinde KOH varlığında reaksiyona girmesiyle 1-(3,5-dikloro-2-hidroksifenil)- 3-p-tolil prop-2-en-1-on (3’,5’-Dikloro-2’-hidroksi-4- metil şalkon) bileşiği sentez edilmiştir. Daha sonra elde edilen bu bileşiğin etanol içerisinde geri çeviren soğutucu altında izonikotinik asit hidrazit ile muamele edilmesiyle [3-(3,5-dikloro-2-hidroksifenil)-5-p-tolil-4,5- dihidropirazol-1-il] (piridin-4-il) metanon bileşiği sentez edilmiştir. Yapısı doğrulanan bu bileşiğin hMAO enzimi ile etkileşimi, ticari tayin kiti kullanılarak fluorometrik bir yöntemle incelenmiştir. Ayrıca, söz konusu yeni bileşik ile hMAO arasındaki etkileşimler, moleküler modelleme çalışmaları ile aydınlatılmıştır. Bulgular: Sentezlenen bileşiğin yapısı, IR, Mass, 1H-NMR ve elemental analiz yöntemleri kullanılarak doğrulanmıştır. Yapısı doğrulanan bu bileşiğin etkin, seçici, tersinir, toksik olmayan bir hMAO-B inhibitörü olduğu ve inhibisyonun yarışmalı olduğu görülmüştür. Moleküler yerleştirme programı kullanılarak bileşiğin hMAO-B enziminin aktif bölgesinde hangi amino asit yan zincirleri ile ne tür girişimleri yaptığı belirlenmiştir. Sonuç: Yeni sentezlenen SH2U bileşiği, hMAO-B enzimini kuvvetle, seçici, yarışmalı ve tersinir olarak inhibe etmiştir. Sentezlediğimiz bileşik, bilinen seçici ama tersinmez MAO-B inhibitörü olan selejilin’den daha etkin ve seçici, tersinir olarak hMAO-B enzimini inhibe etmiştir ve Parkinson ile Alzheimer hastalığı tedavisinde kullanılabilecek bir ilaç etken maddesi olarak ümit vadetmektedir.
Citation Count: 0
Alternative Transducer Power Gain Expression in Broadband Matching Network Designs
(IEEE, 2016) Şengül, Metin Y.
In this paper a reflection coefficient based transducer power gain expression has been derived which is an alternative to the impedance based expression exists in the literature. A broadband double matching problem is solved by using the derived gain expression and the obtained performance has been compared with the performance obtained via the existing expression.
Citation Count: 1
An Analysis for the Use of Compressed Sensing Method in Microwave Imaging
(IEEE, 2017) Çalışkan, Cafer; Tekbaş, Mustafa; Ünal, İlhami; Erdoğan, Sercan; Çalışkan, Cafer
One of the most important problems encountered in microwave imaging methods is intensive data processing traffic that occurs when high resolution and real time tracking is desired. Radar signals can be recovered without loss of data with a randomly selected subset of the measurement data by compression sensing (CS) method which has been popular in recent years. For this reason, in this study, the use and capabilities of the CS method were investigated for tracking moving human, and the target information was correctly determined for the data obtained much below the Nyquist sampling criterion. In this study, it was revealed that the CS method can be developed for target detection and tracking
Citation Count: 1
An analysis for the use of compressed sensing method in microwave imaging [Mikrodalga Görüntülemede Sıkıştırılmış Algılama Yönteminin Kullanımına Yönelik Bir Analiz]
(Institute of Electrical and Electronics Engineers Inc., 2017) Çalışkan, Cafer; Tekbaş, Mustafa; Ünal, İlhami; Erdogan, Sercan; Çalışkan, Cafer
One of the most important problems encountered in microwave imaging methods is intensive data processing traffic that occurs when high resolution and real time tracking is desired. Radar signals can be recovered without loss of data with a randomly selected subset of the measurement data by compression sensing (CS) method which has been popular in recent years. For this reason in this study the use and capabilities of the CS method were investigated for tracking moving human and the target information was correctly determined for the data obtained much below the Nyquist sampling criterion. In this study it was revealed that the CS method can be developed for target detection and tracking. © 2017 IEEE.
Citation Count: 1
Anomaly Detection in Walking Trajectory
(IEEE, 2018) Öğrenci, Arif Selçuk
Analysis of the walking trajectory and the detection of anomalies in this trajectory, provide important benefits in the fields of health and security. In this work, two methods to detect anomalies in trajectories, are compared. Firstly, an unsupervised method is used where the conformance among trajectories are taken into consideration. Trajectories that deviate from others are qualified as anomalies. Secondly, the points in the trajectories are considered as a time series. Artifical neural networks performing supervised learning based on the backpropagation algorithm are used. The results are compared, and the points to be enhanced are highlighted.
Citation Count: 2
Anomaly detection in walking trajectory [Yürüyüş yörüngesinde anormallik algılama]
(Institute of Electrical and Electronics Engineers Inc., 2018) Öğrenci, Arif Selçuk
Analysis of the walking trajectory and the detection of anomalies in this trajectory provide important benefits in the fields of health and security. In this work two methods to detect anomalies in trajectories are compared. Firstly an unsupervised method is used where the conformance among trajectories are taken into consideration. Trajectories that deviate from others are qualified as anomalies. Secondly the points in the trajectories are considered as a time series. Artifical neural networks performing supervised learning based on the backpropagation algorithm are used. The results are compared and the points to be enhanced are highlighted.
Citation Count: 0
Broadband Matching via Reflection Coefficient Modeling
(AVES YAYINCILIK, 2016) Şengül, Metin Y.
[Abstract Not Available]
Citation Count: 1
Busy tone based power control for coordination of IEEE 802.11af and 802.22 system [IEEE 802.11af ve 802.22 Sistemlerinin Uyumlu Çalışmaları için Meşgul Ton Tabanlı Güç Kontrolü]
(Institute of Electrical and Electronics Engineers Inc., 2017) Baykaş, Tunçer; Erküçük, Serhat; Karatalay, Onur; Baykaş, Tunçer
In this paper a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies in addition to both 802.11af access point and clients listening to the busy tone they also adjust their communication power according to the location information and use hopping for communication if needed. Acccordingly interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards. © 2017 IEEE.
Citation Count: 1
Busy Tone Based Power Control for Coordination of IFFY 802.11af and 802.22 System
(IEEE, 2017) Baykaş, Tunçer; Erküçük, Serhat; Karatalay, Onur; Baykas, Tuncer
In this paper, a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies, in addition to both 802.11af access point and clients listening to the busy tone, they also adjust their communication power according to the location information and use hopping for communication, if needed Acccordingly, interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards.
Citation Count: 1
Busy Tone Implementation for Coexistence of IEEE 802.22 and 802.11 af Systems
(IEEE, 2015) Baykaş, Tunçer; Erküçük, Serhat; Baykaş, Tunçer
In this paper a new algorithm based on busy tone approach has been proposed for the coexistence of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier study in addition to 802.11af access points listening to the busy tone signal their clients also listen to the busy tone and let the access points know once they hear it. Accordingly interference caused to 802.22 systems has been reduced. This study quantifies the improved system performance in terms of interfering packet rate for different hearing regions considering the communication parameters and channel models adapted for the standards.
Citation Count: 0
Büyük Patlama – Büyük Çöküş Optimizasyon Yöntemi Kullanılarak Bluetooth Tabanlı İç Mekan Konum Belirleme Sisteminin Doğruluğunun İyileştirilmesi
(Süleyman Demirel Üniversitesi, 2018) Arsan, Taner
Düşük enerjili Bluetooth işaretçi (Bluetooth low energy - BLE beacon) teknolojisi, iç mekan konum belirleme sistemlerinde başarılı ve düşük maliyetli çözümler sunan gelişmekte olan bir teknolojidir. Bu çalışmada, BLE işaretçileri (beacons) kullanan bir iç mekan konum belirleme sistemi geliştirilmiş, kullanılan ilave algoritmalarla standart sensörlerden elde edilen konum değerlerinin doğruluğunun artırılması amaçlanmıştır. Bunun için, deneysel iç mekan konum algılama sisteminden elde edilen konum bilgilerine Büyük Patlama – Büyük Çöküş (Big Bang – Big Crunch (BB-BC)) optimizasyon yöntemi uygulanmış ve konum doğruluğunun geliştirildiği yapılan testlerle kanıtlanmıştır. Test alanı olarak, 9,60 m × 3,90 m boyutundaki 37,44 m2'lik alan seçilmiş ve 2,40 m × 1,30 m boyutundaki oniki tane ızgara alanına ayak izi (fingerprinting) algoritması uygulanmıştır. Test alanına dört tane BLE işaretçi (beacon) yerleştirilmiş, on iki test alanından 150 saniye boyunca toplam 9.000 ölçüm yapılmıştır. Ölçüm sonuçları Büyük Patlama – Büyük Çöküş optimizasyon yöntemi ile Öklid uzaklık eşleştirme yöntemi ve Kalman Filtresi kullanılarak iyileştirilmiş, bu sayede konum doğruluğu %26,62'den %75,69'a arttırılmıştır.
Citation Count: 0
Büyük patlama büyük çöküş optimizasyon yöntemi ile ultra geniş band sensörlerinin iç mekân konum belirleme doğruluklarının iyileştirilmesi
(Pamukkale Üniversitesi, 2018) Arsan, Taner
Ultra geniş band teknolojisi, birçok iç mekân konum belirleme sisteminde başarılı çözümler sunan, diğer yöntemlere kıyasla daha iyi performans gösteren, gelişmekte olan bir teknolojidir. Bu çalışmada, ultra geniş band (Ultra Wide Band-UWB) sensörler kullanılarak bir iç mekân konum belirleme sistemi geliştirilmiş ve kullanılan ek algoritmalarla, standart donanımların sağladığı doğruluk düzeyi arttırılırken aynı zamanda ortalama hatayı azaltmak hedeflenmiştir. Bu amaçla Büyük Patlama - Büyük Çöküş (Big Bang-Big Crunch veya BB-BC) optimizasyon yöntemi deneysel iç mekân konumlandırma sistemine uygulanmış ve ölçüm doğruluğu üzerindeki olumlu etkisi yapılan testlerle kanıtlanmıştır. Test alanı olarak 7.35 m × 5.41 m boyutlarında 39.76 m2 'lik bir alan seçilmiş ve özel olarak tasarlanmış bir tavan sistemine yerden 2.85 m yüksekliğe üç farklı UWB alıcı yerleştirilmiş ve 182 adet test noktasından 60 sn.süreyle toplam 10.920 ölçüm alınmıştır. Ölçüm sonuçları Büyük Patlama - Büyük Çöküş optimizasyon algoritması ile düzeltilerek, ortalama hatası önceki 20.72 cm değerinden 15.02 cm’ye düşürülmüş, böylelikle ölçüm sonuçlarının doğruluğu arttırılmıştır.
Citation Count: 5
Comparison of Compressed Sensing Based Algorithms for Sparse Signal Reconstruction
(IEEE, 2016) Erküçük, Serhat; Başaran, Mehmet; Erküçük, Serhat; Çırpan, Hakan Ali
Compressed sensing theory shows that any signal which is defined as sparse in a given domain can be reconstructed using fewer linear projections instead of using all Nyquist-rate samples. In this paper we investigate basis pursuit matching pursuit orthogonal matching pursuit and compressive sampling matching pursuit algorithms which are basic compressed sensing based algorithms and present performance curves in terms of mean squared error for various parameters including signal-tonoise ratio sparsity and number of measurements with regard to mean squared error. In addition accuracy of estimation performances has been supported with theoretical lower bounds (Cramer-Rao lower bound and deterministic lower mean squared error). Considering estimation performances compressive sampling matching pursuit yields the best results unless the signal has a non-sparse structure.
Citation Count: 0
Effect of channel estimation errors on the performance of space time coded systems with antenna selection
(IEEE, 2007) Güçlüoğlu, Tansal; Panayırcı, Erdal
This paper presents the effects of channel estimation errors on the performance especially diversity gain of space-time coded systems with antenna selection. We consider maximum signal to noise ratio as the antenna selection criteria. Specifically we first present the effect on the upper bound for pairwise error probability of space-time coded systems with antenna selection over flat fading channels. Moreover we provide simulation results for the antenna selection at the receiver and/or transmitter to show the effect of channel estimation.
Citation Count: 1
The effect of channel resolution on compressed sensing based Ultra-Wideband channel estimation [Kanal çözünürlü?ünün sıkıştırılmış algılama tabanlı ultra geni?ş bantlı kanal kesti?ri?mi?ne etki?si?]
(2011) Erküçük, Serhat; Erküçük, Serhat; Cirpan, Hakan Ali
Ultra short pulses are transmitted in Ultra-Wideband (UWB) communications. As a result of this pulses at the receiver can be resolved individually due to the sparse structure of the channel. Due to these properties the UWB channel can be estimated by using a compressed sensing based channel estimation method. The performance of channel estimation depends on the sparsity of the channel. In this work the effect of channel resolution which directly affects the sparsity is examined. It is shown that the channel becomes more sparse and the channel estimation performance is improved with increased channel resolution. Also the system performances of practically used selective-Rake receivers with estimated channels are found to be close to the perfect channel estimation case. © 2011 IEEE.
Citation Count: 0
The Effect of Data Augmentation on ADHD Diagnostic Model using Deep Learning
(IEEE, 2019) Özmen, Atilla; Özmen, Atilla; Akan, Aydin
Attention Deficit Hyperactivity Disorder (ADHD) is a neuro-behavioral hyperactivity disorder. It is frequently seen in childhood and youth, and lasts a lifetime unless treated.The ADHD classification model should be objective and robust. Correct diagnosis usually depends on the knowledge and experience of health professionals. In this respect, an automated method to be developed for the ADHD classification model is of great importance for clinicians. In this study, the effect of data augmentation on ADHD classification model with deep learning was investigated. For this purpose, magnetic resonance images were taken from NPIstanbul NeuroPsychiatry Hospital and ADHD-200 database. Since the images were not sufficient in terms of training, data augmentation methods were applied and by convolutional neural network (CNN) architecture, these data were classified and tried to reveal the diagnosis of the disease independently from the non-objective experiences of the health professionals.
Citation Count: 2
The Effect of Energy Geopolitics on International Climate Change Initiatives
(Uluslararası İlişkiler Konseyi Derneği, 2017) Ediger, Volkan S.
In this article in general the relationship between international climate change initiatives and energy geopolitics was analyzed and in particular the developments in energy geopolitics were investigated with a historical point of view by dividing the years between 1965 and 2014 into periods of geopolitical intensity and geopolitical stability based on long-term periodic variations in oil prices. More specifically the reasons why international initiatives such as the Kyoto Protocol regarded as an important agreement for imposing commitments in climate change mitigation have not been sufficiently successful were investigated. Regarding the Kyoto Protocol the failure stemmed from three main reasons. The first and the most important reason was the intensification of geopolitical tensions on a global scale. The second reason was the differences among states in terms of their energy needs and possession of indigenous energy sources. The last reason was the ambiguity regarding the role of the state and the market at the implementation level. The author links the general failure in the efforts to tackle climate change to the developments in energy geopolitics and argues that the competition periods in energy geopolitics as observed during the oil crises decrease the chances of success for international initiatives on climate change.
Citation Count: 2
The effect of secondary user locations on the cooperative detection performance [İki?nci?l kullanıcı konumlarının i?şbi?rli?kli? algılama yöntemi? performansına etki?si?]
(IEEE, 2012) Erküçük, Serhat; Erküçük, Serhat
In conventional cooperative detection a fusion center decides on the presence or absence of the primary user by gathering all the information from secondary users and conveys this decision to all users. This approach does not take into account the locations of the secondary users where a user far from the primary user may also have to keep silent. In a recent work there has been a new detection method based on combining received signals from more than two users obtaining decision tables and deciding individually for each user. While the proposed method showed promising results for the secondary users the effect of the user distribution was not investigated. In this study we consider the effect of secondary user location and number on the detection performance. We show that (i) the evaluation of the conventional method in the proposed method is not accurate and (ii) depending on the user location the detection performance may be better or worse compared to the conventional detection. © 2012 IEEE.
Citation Count: 0
Effect of the Channel Estimation Error on the Performance of the Source Estimator in a Wireless Sensor Network with Orthogonal Channels
(IEEE, 2008) Şenol, Habib; Tepedelenlioğlu, Cihan
In this work effect of the channel estimation error on the MSE performance of the source estimator in a wireless sensor network with orthogonal flat fading channels is studied. A two-phase approach was employed where in the first phase the orthogonal fading channel coefficients are estimated and in the second phase channel estimates and sensor observations transmitted to fusion center are used for the source estimation. We consider a sensor network in which the channel estimates are fed-back to the sensors for optimal power allocation which leads to switch off the sensors with bad channels in the second phase. We also show that training power should be at least half of the total power. Our analytical findings are corroborated by simulation results.
Citation Count: 1
Effects of channel models and optional data rates on the IEEE 802.15.4a system performance [Kanal modellerinin ve seçime bağli veri hızlarının IEEE 802.15.4a sistem başarımına etkileri]
(2010) Erküçük, Serhat; Erküçük, Serhat
The wireless personal area network standard IEEE 802.15.4a uses ultra wideband impulse radios (UWB-IRs) for precise ranging and location and as well as for communications at low data rates (about 1 Mb/s). In addition to low data rates there are optional data rates defined in the standard that can support up to 27 Mb/s. In this paper the IEEE 802.15.4a system performance is studied for optional data rates in addition to considering the effect of channel models at the mandatory data rate. For the considered channel models system performances are evaluated for different numbers of Rake fingers and the error correction capability of channel encoding is tested at various data rates. The results of this study are important for the implementation of the IEEE 802.15.4a standard. ©2010 IEEE.

Browse

Browsing Mühendislik ve Doğa Bilimleri Fakültesi by Language "tr"