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A low-power multilevel CMOS classifier circuit
Get PDFİnsanların günlük yaşamında belirli bir sesi, görüntüyü veya analog bir veriyi tanımak için kullandıkları kuralları tanımlamak oldukça karmaşık bir dizi işlem gerektirmektedir ve hatta bu kuralları tanımlamak bazen mümkün olamamaktadır. Oysa pratikte karşılaşılan örüntü tanıma olaylarını, yazılım ve donanım tabanlı tanıma uygulamalarında belirli kriterlere oturtmak mümkündür. Sınıflandırma yöntemleri ilk olarak örüntü sınıflandırma adı altında görülmeye başlanmış ve ilk algoritmalarda basit yapılar ele alınmıştır; ilk gerçeklenen yapıda en yakın komşu yakınsaması kullanılmıştır. Sınıflandırma işlemi, benzer özellik taşıyan objelerin başka farklı özellikte olanlardan ayırt edilmesi şeklinde tanımlanabilir ve otomatik hedef belirleme, yapay zekâ, yapay sinir ağları, analog-sayısal dönüştürücüler, kuantalama, tıbbi tanı, istatistik gibi çeşitli alanlarda kullanılır. Dolaysıyla da, günümüzde, gerek gerçek dünyada gerekse sayısal dünyada verilerin sınıflandırılması büyük önem taşımaktadır. Bugüne kadar sınıflandırma işlemi genellikle çeşitli algoritmalar yardımıyla yazılımsal olarak yapılmaktaydı, oysa birçok uygulamada, sınıflandırma işlemini daha hızlı ve gerçek zamanda yapmak gerektiğinden bu algoritmaların donanımsal olarak gerçeklenmeleri çok daha yararlı olmaktadır. Ayrıca günümüzde portatif cihazların da artmasından dolayı donanımsal olarak gerçeklenecek cihazlarda da güç tüketimi büyük önem kazanmıştır. Dolayısıyla sınıflandırıcı devrelerin de bu ihtiyaçları karşılayacak şekilde tasarlanması gerekmektedir. Bu makalede akım-modlu düşük güçte çalışan bir sınıflandırıcı devresi sunulmaktadır. Önerilen sınıflandırıcı devresi, temel bir bloktan yararlanmaktadır; bu temel bloklar kullanılarak daha gelişmiş sınıflandırıcı yapılarının gerçekleştirilebileceği gösterilmiştir. Önerilen devrenin benzetimleri için 0.35 µm AMS CMOS teknoloji parametreleri kullanılmıştır. Ayrıca çekirdek devre adı verilen temel bloğun, tek boyutlu ve iki boyutlu sınıflandırıcı yapılarının benzetim sonuçları verilmiştir. Anahtar Kelimeler: Sınıflandırıcı devreler, CMOS, akım modlu, düşük güç.In the everyday life of humans, to define the rules used to recognize a certain sound, image or an analog data necessitates a sequence of complex processes which sometimes becomes impossible to accomplish. However, to develop well defined software and hardware based criteria in the application of pattern recognition problems, is possible. The aim of classification can be defined as to assign an unknown object to a class containing similar objects (or to distinguish objects having the same properties from those not possessing). Classification is especially important in the real world applications or in the digital world. Basic classification methods using nearest neighbourhood algorithm have first been seen in early sixties under the subject tile" pattern recognition." Classification is used in a huge variety of applications such as automatic target identification, artificial neural networks, artificial intelligence, template matching, pattern recognition, analog to digital converters, quantization, medical diagnosis, statistics etc. Therefore nowadays, be it in the real or digital world, data classification is becoming increasingly important. But until recently, major work on classification was on developing algorithms used in software packages whereas, in many applications it is becoming more and more important to classify data much faster and in real time, entailing the need for hardware realization of these algorithms. Software approaches are not practical for real time applications, the processing is computationally very expensive, consuming a lot of Central Processing Unit (CPU) time when implemented as software running on general purpose computers. So in literature hardware implementation of classifier topologies become necessary. Also in literature hardware realized classifiers which are designed to work in low power operation; moreover some of these hardware classifiers do not have custom tunability. So they can only be used for a specific application. The recent developments in electronics technology has created a perfect medium for the hardware realization of classifier structures which, in turn, will render many classifier application prospects feasible in real time. This paper targets the design and application to real world problems of tunable, low power new classifier circuits using CMOS technology. So, a low-power CMOS implementation of a multi-input data classifier with several output levels is presented. The proposed circuit operates in current-mode and can classify several types of analog vector data. An architecture is developed comprising a threshold circuit based on CMOS transistors operating in subthreshold region. To this purpose a one dimensional classifier, called core circuit is proposed. The core circuit also works as a one-dimensional classifier. As this circuit is designed to operate in current-mode the input and the output data is provided to the core circuit with currents. So by interconnecting several core circuits and adding the output currents a multi output classifier can be obtained. Also, com-bining several core circuits in groups in such a way that each group has identical input current (different from the others), a multi-dimensional, multi-level output classifier can be obtained. Also, numerous efforts in balancing the trade off between power consumption, area and speed have resulted in an acceptable performance. On the other hand, the rapid increasing use of battery operated portable equipment in application areas such as telecommunications and medical electronics increases the importance of low-power and small sized VLSI circuits' technologies. One solution to achieve low-power and acceptable performance is to operate the transistors in the subthreshold region. The CMOS transistors working in subthreshold region are suitable only for specific applications which need, not very high performance, but low power consumption.The primary aim of this paper is to develop a low power classifier circuit with n inputs and externally tunable decision regions with different output amplitude for each region. Due to the subthreshold operation of the transistors in the proposed core circuit, very low power consumption becomes possible. The proposed core circuit is constructed with two threshold and a subtractor circuit. The SPICE simulation of the threshold circuit, core circuit, one dimensional and two dimensional classifier circuits are given. Using 0.35 µm parameters of AMS CMOS technology, SPICE simulations are performed and a low-power, custom tunable classifier circuit is realized. Because of the parallel processing characteristic of the circuit, it is well suited for real-world applications. Keywords: Classifier circuits, CMOS, current-mode, low-power
Efficient concatenated trellis code and coordinate interleaved orthogonal designs for OFDM
Get PDF Bu çalışmada, OFDM için yüksek başarımlı sıralı kafes kodlar ve bileşen serpiştirmeli dik tasarımlar (TC-CIOD) önerilmektedir. OFDM’in başarımını arttırmak için bileşen serpiştirici ve kafes kod birlikte kullanılmıştır. Sistemde kullanılan bileşen serpiştirici, işaret uzayı çeşitlemesi sağlamakta ve geniş bantlı kanallarda sistemin kod sözcük hata olasılığı (CER) başarımını iyileştirmektedir. İki verici antenli durumda, önerilen sistemin kod sözcük çiftleri arasındaki ikili hata olasılığı (PEP) çözümlenmiş ve elde edilen sonuçlardan sistemin tam uzaysal ve yüksek çok-yollu çeşitleme kazancı sağladığı belirlenmiştir. Eş kafes kullanıldığında, TC-CIOD kodlar, Gong ve Letaief (2003)'in önerdiği çift-simge serpiştirmeli sıralı kafes kod ve uzay-zaman blok kodlara (TC-STBC) göre dört kat fazla çeşitleme kazancına erişebilmektedir. Gong ve Letaief (2003) tarafından önerilen TC-STBC sistemde kafes kod ile STBC arasındaki serpiştirici göz ardı edildiğinden elde edilen sonuçlar kafes kod çıkışındaki simgelerin çiftler halinde serpiştirildiği duruma eşdeğerdir. Bu referans sistem için çift-simge serpiştirmeli TC-SBTC isimlendirmesi kullanılmıştır. Serpiştiricinin TC-STBC’nin erişebildiği çeşitleme kazancı üzerindeki etkisini ortaya çıkarmak için, çift-simge serpiştirmeli TC-STBC durumunda geçerli olan sonuçlar, simge serpiştirmeli duruma genişletilmiştir. PEP çözümlemesi sonuçları kullanılarak yapılan ve kod sözcük hata olasılığı üst sınırını enküçülten bilgisayar destekli kafes kod aramayla, TC-CIOD için eniyileştirilmiş 4, 8, 16, ve 32-durumlu 2/3 kodlama oranlı 8-PSK kafes kodlar belirlenmiştir. Bilgisayar destekli benzetim sonuçlarına göre 4, 8, 16 ve 32-durumlu kafes kod kullanıldığında önerilen TC-CIOD sistemi, referans TC-STBC'ye (Gong ve Letaief, 2003) göre 10-3’lük CER'de, sırasıyla, yaklaşık 10.7 dB, 10.2 dB, 4.8 dB ve 4.2 dB ek işaret-gürültü oranı (SNR) kazancı sağlamaktadır. TC-STBC ile karşılaştırıldığında, önerilen sistemin sağladığı yüksek SNR kazancı, kodlama ve kod çözme işlem karmaşıklığındaki küçük bir artışla mümkün olmaktadır. Anahtar Kelimeler: OFDM, uzay-zaman kodlama, çok-yollu çeşitleme, bileşen serpiştirme.On rising demand for high quality, mobility and data rate, a considerable effort has been given to develop robust coding techniques for wideband channels. Significant achievements are obtained with multiantenna communications and Orthogonal Frequency Division Multiplexing (OFDM). After the work of Agrawal et al. (1998), the application of Space-Time Block Codes (STBC) to OFDM was suggested by Lee and Williams (2000). Afterwards, the efforts to increase the performance of Multiple-Input Multiple-Output (MIMO) OFDM systems are ongoing. The MIMO OFDM system performance is primarily affected by achieved diversity, and there is a tradeoff between rate, diversity and constellation size. Hence, the only way to increase the diversity in a wideband channel, with unlimited number of channel taps, fixed number of transmit and receive antennas, fixed bandwidth, and bandwidth efficiency, is to extend the constellation of the signals modulating OFDM subcarriers and to encode through these subcarriers. Such systems achieving multipath diversity in wideband channels are the Linear Constellation Precoded (LCP) OFDM and the concatenated LCP and STBC (LCP-STBC) OFDM proposed by Liu et al. (2003; 2002). It is further possible to achieve multipath diversity by trellis encoding through OFDM subcarriers. Such system is the serial concatenated outer convolutional code and LCP-STBC (SC-LCP-STBC) proposed by Wang et al. (2003). The high computational complexity of Maximum Likelihood (ML) sphere decoder (Damen et al., 2000) used with LCP-STBC and turbo decoder used with SC-LCP-STBC leads to a search for techniques with lower decoding complexities. The concatenation of an outer trellis code and STBC (TC-STBC) for OFDM proposed by Gong and Letaief (2003) is an effective coding technique with simple Viterbi decoding. In this system the 8-PSK trellis codes (Jamali and Le-Ngoc, 1991; Schlegel and Costello, 1989) designed for fast fading channels are involved. Gong and Letaief (2003) showed that TC-STBC has superior performance compared to the other trellis coded MIMO OFDM systems (Agrawal et al., 1998; Lu and Wang, 2000). On the other hand, coordinate interleaving (Boulle and Belfiore, 1992; Jelicic and Roy, 1994), applied to MIMO OFDM by Rao et al. (2004), is a powerful technique providing diversity by extending the considered signal constellation. Additionally, the single symbol decodability of Coordinate Interleaved Orthogonal Designs (CIOD) is an important feature ensuring low decoding complexity.In this paper, we propose a concatenated outer trellis code and CIOD (TC-CIOD) OFDM system for high-speed wireless transmission. Our system combines a coordinate interleaver and trellis code to boost the MIMO OFDM performance.The coordinate interleaver provides signal space diversity and improves the Codeword Error Rate (CER) performance of the system in wideband channels. The pairwise error probability analysis of the new system for two transmit antennas shows that the system provides full spatial and multipath diversity, and the TC-CIOD achieves diversity as high as SC-LCP-STBC (Wang et al., 2003) and nearly four times greater than TC-STBC system (Gong and Letaief, 2003), while still preserving the advantage of simple ML Viterbi decoding. To clarify the effect of interleaver selection on the achieved diversity of TC-STBC, we extend the results given by Gong and Letaief (2003), where a two-symbol interleaver is con-sidered between the trellis code and STBC, to the symbol interleaver case, which doubles the achieved diversity of TC-STBC. We further show that the coordinate interleaved TC-CIOD doubles the achieved diversity of symbol interleaved TC-STBC. To optimize the performance of TC-CIOD, the trellis design criteria are derived by codeword error probability analysis, and new 4, 8, 16 and 32-state rate 2/3 8-PSK trellis codes are found by computer based exhaustive search. Finally, the computer simulations are performed to obtain the Codeword Error Rate (CER) performances which show that the proposed system considerably outperforms the existing sys-tems (Gong and Letaief, 2003; Agrawal et al., 1998; Lee and Williams, 2000; Liu et al., 2002; Rao et al., 2004). According to the computer simulations, the proposed system outperforms the reference system (Gong and Letaief, 2003) by 10.7 dB, 10.2 dB, 4.8 dB and 4.2 dB in signal-to-noise ratio at the CER of 10-3 when 4, 8, 16 and 32-state trellis codes are employed, respectively, with a modest increase in encoding and decoding complexities. Keywords: OFDM, space-time coding, multipath diversity, coordinate interleaving
Fuzzy supervisory control of Rotor-AMB system and bias current optimization
Get PDFThis paper presents the Fuzzy Supervisory Control (FSC) and bias current optimization algorithm developed for a Rotor-Active Magnetic Bearing (Rotor-AMB) system. Since the AMBs are inherently unstable, it is essential to use a controller for a stable levitation. Initially, a closed loop control of Rotor-AMB system is achieved and the whole model is built in a virtual environment (MatlabÒ/ Simulink). With the help of simulation model the system dynamics is analyzed. In addition to that, the effect of bias current on energy consumption is studied for both unidirectional and differential control current strategies. A diffential current control gives better efficiency compared with a unidirectional approach when the bias current is variable. Thus, optimizing the bias current according to the operational conditions is beneficial for magnetically levitated systems. According to the results obtained an energy optimization algorithm (EOA) is developed. Since the system is nonlinear and has some uncertainties a Fuzzy Supervisory Controller is used to overcome these problems. Then, the real time model of the FSC and EOA are achieved using dSPACE. Finally an experimental set up is formed and FSC+EOA are applied to the Rotor-AMB system. It is shown that, FSC and the algorithm developed make the system tolerant to higher unbalances and disturbances with minimum energy consumption. Keywords: Active magnetic bearing, fuzzy logic, energy.Bu çalışmada, Rotor-Aktif Manyetik Yatak (AMY) sistemi için tasarlanılan Bulanık Denetleyici Kontrolör (BDK) ve sistemde harcanılan enerjiyi azaltmayı sağlayan enerji eniyileştirme algoritması (EİA) sunulmuştur. Başlangıçta sistem dinamiğini incelemek için sisteme ait benzetişim modeli MatlabÒ/ Simulink ortamında gerçekleştirilmiştir. Oluşturulan model ile denge akımının enerji kaybına olan etkisi literatürde yer alan iki farklı yöntemi için incelenmiştir. Elde edilen sonuçlardan hareket ile enerji eniyileştirme algoritması geliştirilmiş ve sistemin kontrolünde kullanılan BDK’ya bağlanmıştır. Gerçekleştirilen BDK+EİA, dSPACE modülü yardımı ile Rotor-AMY sistemine uygulanmıştır. Sonuçta sistem parametrelerinin aynı anda değiştirilmesi ile dinamik yapının uygun katılıkta ve en az enerji harcayacak biçimde çalıştığı deneysel olarak gösterilmiştir. Anahtar Kelimeler: Aktif manyetik yatak, bulanık mantık, enerji
Effect of infill walls and strengthening of the infill walls on the behavior of reinforced concrete frames
Get PDFIt is known that most of the reinforced concrete frame buildings in our country are not strong enough to resist the strong or even moderate earthquakes. It is very common that such structures are strengthened before earthquakes or repaired or strengthened being slightly or fairly damaged after the earthquakes. Filling a certain number of reinforced frames with infill walls in order to increase the resistance of these structures to earthquakes may be an economic solution. If the infilled frame is analyzed well, designed properly and produced accordingly, it may behave as a shear wall resulting in an increase in the stiffness and strength and hence the other structural members may not need to be strengthened. Most of the reinforced structures currently in use do not usually have enough lateral strength and stiffness, do not proper reinforcement details, and have concrete of low quality. In addition to this, the fact that there are system defects such as weak story, short column, and strong beam-weak column leads to a very large stock of buildings with insufficient earthquake resistance. It is impossible to expect that these buildings having such weaknesses will respond properly to a strong excitation. For this reason, there is need to increase the seismic safety of present building stock with an order of priority. In view of the number of buildings requiring the strengthening, it is impossible to strengthen all these buildings in a way to preserve the usability of the buildings after an earthquake. On the other hand, in order to minimize the loss of life and property, it is needed to prevent these buildings from collapsing under a strong earthquake. For the purpose of enabling the strengthening of dwellings and industrial structures in use, there is need to develop economical methods not requiring the evacuation of the structures, rapid and applicable without the interruption of the structural use. It is known that hollow-bricked walls increase both the lateral stiffness and strength of the reinforced concrete frames as long as lateral deformations do not exceed a certain threshold. Having said this, if the lateral displacements exceed a certain level, the infill walls do not play any role due to crushing and tilting and, consequently, they do not provide any resistance to response of reinforced concrete frame during the earthquake shaking. To gain more of the infill walls during an earthquake and to take advantage of their stiffness and strength enhancement, research studies on the infill walls have been carried out.This study comprises a test series of strengthening of reinforced frame with infilled brick wall which is assumed to be damaged or defective work. In this work, 3 reinforced concrete frames ½ scaled, one-bay, one-story with unreinforced infill walls were produced. One of these specimen is tested without infill walls. The second frame formed with infill wall is subjected to experiment to investigate its influence. The third frame is strengthened by applying mesh reinforcement and cover plaster on infill walls based on the parameters of 2007 Turkish Seismic Code. These above frames were tested under reversed cyclic loading. To obtain the built-in condition, frames with weak column and strong beam on a rigid continuous foundation were manufactured with low strength concrete. In this experimental study the influence of infill wall and strengthening of infill wall was investigated and changes in stiffness and lateral load carrying capacities, and energy absorption capacity were examined. By changing the bare frame into the infilled one, its lateral load carrying capacity has been increased 3.7 times and its stiffness 34 times. As such, the influence of infill walls has become apparent. The increase in the load-carrying capacity provided by the strengthening of the infill walls has also been obtained graphically. Through the strengthening of infilled wall frame with mess reinforcement and mortar, the lateral load capacity of the specimen has been increased 1.8 times. By strengthening the infilled wall frame in accordance with the Earthquake Code specifications, an increase of 80% in its lateral load carrying capacity has been obtained. Such strengthening yields an increase of around 80% in the lateral stiffness. After testing of the frame specimen, it is seen that infilled wall frame has 7 times more energy absorption capacity than the bare frame and strengthened frame 3.2 times more than infilled wall frame. Keywords: Infill walls, RC frames, reinforcement, wire mesh reinforcement.Ülkemizde betonarme çerçeve taşıyıcı sistemine sahip binaların birçoğunun, büyük hatta orta şiddetteki depremlere dayanabilecek kalitede olmadığı bilinmektedir. Bu tip binaların deprem öncesi güçlendirilmeleri veya depremi az veya orta hasarlı atlattıktan sonra onarılması ve güçlendirilmesi pratikte oldukça yaygındır. Bu tür yapıların depreme karşı güçlendirilmesi amacıyla belli sayıda betonarme çerçevenin betonarme dolgu duvarlar ile doldurulması ekonomik bir çözüm olabilmektedir. Dolgulu çerçeve iyi analiz edilip, gerektiği gibi projelendirilir ve imal edilirse, perde duvar gibi davranarak yapının yanal rijitliğini ve dayanımı artırabilir ve böylece diğer taşıyıcı elemanların güçlendirilmesine ihtiyaç duyulmayabilir. Bu çalışma kusurlu olarak üretildikleri varsayılan yapılara ait tuğla dolgu duvarlı betonarme çerçevelerin, duvar yüzeyine uygulanan hasır donatı ve sıva ile güçlendirilmelerine yönelik deneysel çalışmayı içermektedir. Bu çalışmada 3 adet tek katlı tek açıklıklı ½ ölçekli betonarme çerçeve üretilmiştir. Numunelerden biri boş olarak deneye tabi tutulmuştur. İkinci numuneye duvar örülerek deneye tabi tutulmuş ve bölme duvar etkisi araştırılmıştır. Diğer numune ise dolgu duvar üzerine çelik hasır uygulaması 2007 TDY’de verilen parametreler esas alınarak güçlendirilmiş ve deneyler gerçekleştirilmiştir. Bu amaçla hazırlanan üç adet çerçeve elemanı, tersinir tekrarlanır yatay yük etkisi altında test edilmiştir. Bu imalatlarda tam ankastreliği sağlamak için bir rijit temel ve bu temel üzerine, tek katlı, tek açıklıklı, beton basınç dayanımı düşük, güçlü kiriş ve zayıf kolondan oluşan çerçeveler imal edilmiştir. Bu deneysel çalışmada bölme duvarının ve bölme duvar güçlendirmesinin çerçeve davranışına etkisi araştırılmış ve test edilen elemanların yatay yük taşıma kapasiteleri, rijitlik ve enerji yutma kapasitelerindeki değişim incelenmiştir. Anahtar Kelimeler: Dolgu duvar, betonarme çerçeve, güçlendirme, çelik hasır donatı. 
Applying the generated neuro-fuzzy method on determining climate zones of Turkey and testing its performance
Get PDFA neural network can approximate a function, but it is impossible to interpret the result in terms of natural language. The fusion of neural networks and fuzzy logic in neuro-fuzzy models provide learning as well as readability. Control engineers find this useful, because the models can be interpreted and supplemented by process operators. A neural network can model a dynamic plant by means of a nonlinear regression in the discrete time domain. The result is a network, with adjusted weights, which approximates the plant. It is a problem, though, that the knowledge is stored in an opaque fashion; the learning results in a (large) set of parameter values, almost impossible to interpret in words. Conversely, a fuzzy rule base consists of readable if-then statements that are almost natural language, but it cannot learn the rules itself. The two are combined in neuro-fuzzy systems in order to achieve readability and learning ability at the same time. The obtained rules may reveal insight into the data that generated the model, and for control purposes, they can be integrated with rules formulated by control experts (operators). This article introduces a method which is a mixture of the fuzzy c-means clustering method and the artificial neural networks (ANN) used in one system. The goal of this method is to obtain clearly separated clusters in high dimensional data space. In order to obtain clear 'obvious' clusters, the cluster centers calculated by the fuzzy c-means method is used as input for the artificial neural networks. Unlike conventional cluster analysis methods and artificial neural networks, the input data is generated according to the coordinates of cluster centers calculated by the fuzzy c-means method. Three different artificial neural network techniques, namely, the Feed Forward Back Propagation (FFBP), the Generalized Regression Neural Networks (GRNN) and the Radial Basis Function-Based Neural Networks (RBFNN) are used in the neuro-fuzzy method in order to achieve better performance. The performance of the proposed method was illustrated using the Iris data set which is commonly used in the international literature. We tested the performance all three cluster analysis methods which were the Ward's method, the Kohonen-ANN and a neuro-fuzzy method developed in this study for defining the precipitation regime regions and the climate zones. The Iris data which is commonly used in the literature for determining the performance of the clustering methods was used to test the performance of the neuro-fuzzy method. The performance of the neuro-fuzzy method was 94% and this result showed that the neuro-fuzzy method can be used in the cluster analyses. This result is better than Ward's method result (89.33%) which is commonly used for defining climate zones, the Kohonen-ANN (88.67%) and the fuzzy Kohonen-ANN (91.33%) which is a mixture of fuzzy set theory and ANN. Thus, an improvement had been made the results of the fuzzy c-means clustering method and the Kohonen-ANN with the created neoro-fuzzy method that uses fuzzy the c-means method and ANN methods. According to the stability analyses of the clustering methods applied in this study were showed that these 3 methods can be applied in the cluster analyses which have different number of stations. The results of the stability analysis of these 3 methods were so close to each other but Kohonen-ANN had showed a bit better performance than the Ward's method and the Kohonen-ANN. A matrix created from the correlation coefficients of the meteorological data were used as input for cluster analysis methods. In the international literature, there is no similar approach like the creation of this correlation matrix. Due to appearance of "sub-climate zones" when the correlation coefficients were used as input, sub-precipitation regime regions" and "sub-climate zones" of Turkey were manage to demonstrate by maps. The generated neuro-fuzzy method's results were more consistent on determination of climate zones considering the influence of large scale pressure systems and upper air circulation, location of transition regions, topography, exposure, continentally, the controls of physical geography and orograpy. The ward's method results didn't used due to unexpected transitition regions. According to the results of the generated neuro-fuzzy method, there is seven main climate region and 15 sub-climate regions in Turkey. The 'sub-climate' regions of the main climate zones are revealed for the first time in the international literature. Keywords: Neuro-fuzzy method, cluster analysis, iris data, climate zones.Bu çalışmada bulanık mantık ve Yapay Sinir Ağlarını (YSA) bir arada kullanan bir bulanık-YSA metodu oluşturulmuştur. Bu metodun amacı çok boyutlu veri uzayında ‘belirgin’ bir şekilde lineer olarak birbirinden ayrılmış kümeler elde etmektir. ‘Belirgin’ kümeleri elde etmek için, bulanık c-ortalamalar metodu ile hesaplanan küme merkezleri koordinatları, YSA metotlarının girdisini oluşturmuştur. Geleneksel küme analizi ve YSA metotlarının aksine giriş verisi bulanık küme merkezleri koordinatlarına göre türetilmiştir. Bulanık-YSA metodunda en iyi sonucu elde etmek için, İleri Beslemeli Geri Yayılımlı Ağ (İBGYSA), Genelleştirilmiş Regresyon Ağı (GRYSA) ve Radyal Tabanlı Fonksiyon Ağları (RTFA) olmak üzere üç farklı YSA metodu kullanılmıştır. Bulanık-YSA metodu, literatürde küme analizi metotlarının performansının test edilmesi için sıkça kullanılan iris verisi üzerinde denenmiş ve % 94’lük bir performans göstererek küme analizi problemlerinde kullanılabileceği gösterilmiştir. Bulanık-YSA modeli, bulanık c-ortalamalar metodu ve YSA tabanlı olduğundan, sonuçları bulanık c-ortalamalar metodu ve YSA’nın küme analizinde kullanılan türü Kohonen YSA (KYSA) ile karşılaştırdığımızda, bulanık-YSA modeli hem bulanık c- ortalamalar metodu (% 90) hem de KYSA’dan (% 88.67) daha iyi sonuç vermiştir. Bulanık-YSA metodu, Türkiye iklim bölgelerinin belirlenmesi için korelasyonlardan oluşan matrisin kullanıldığı küme analizlerinde, Ward metodu ve KYSA metoduna göre daha başarılı bulunmuştur. Yağış rejimi bölgelerinin belirlendiği küme analizlerinde ise Ward metodu bulanık-YSA metoduna göre daha iyi sonuç vermiştir. Anahtar Kelimeler: Bulanık-YSA metodu, küme analizi, iris verisi, iklim bölgeleri
Investigation of upper-mantle anisotropy beneath İstanbul (ISK) broad-band station
Get PDFTürkiyenin tektonik rejimi farklı levha hareketlerinden etkilenmektedir. Avrupa ve Arap levhalarının Zagros bölgesine bindirmesi, Anadolu Levhası’nın Ege’ye doğru olan kaçma hareketinin temel nedeni olmakla beraber, kaçış asıl olarak doğrultu atımlı Kuzey ve Doğu Anadolu fayları boyunca olmaktadır. Makaslama dalgası ayrımlanması analizi çalışmalarından elde edilen hızlı makaslama dalgası doğrultuları, farklı tektonik süreçlerle ilişkilendirilebilir. Gerilme deformasyon, mutlak ve göreceli levha hareketleri, astenosferik akış, geçmiş jeolojik devirlerden kalmış mineral yönlenmeleri bunların başında gelir. Böylelikle, sismik anizotropi çalışmaları, mevcut tektonik ve GPS verileri de göz önünde bulundurularak, bir bölgenin karmaşık tektonik yapısının araştırılmasında kullanılabilir. Marmara Bölgesi’nde üst mantoya ait sismik anizotropi İstanbul (ISK) geniş-bant istasyonunda (KRDAE-UDİM) kaydedilen verilere SKS ayrımlanması analizi uygulanarak incelenmiştir. Bölgenin sismik anizotropik yapısının incelenmesi amacıyla, ISK istasyonundan sağlanan 15 depreme ait kayıtlar veri analiz penceresini otomatik olarak seçen makaslama dalgası ayrımlanması analizi programı ile incelenmiştir. Analiz edilen verilerdeki SKS fazlarında belirgin makaslama dalgası ayrımlanması gözlemlenmiştir. ISK istasyonu için hızlı makaslama dalgası doğrultusu (43.7°) hesaplanmıştır. Elde edilen doğrultu Orta Anadolu’da yer alan Ankara (ANTO) geniş-bant istasyonundan (IRIS-GSN) elde edilen doğrultu (43°) ile karşılaştırılmıştır. Marmara Bölgesi’nin altındaki üst mantoya ait sismik anizotropi yapısının Ankara ve çevresi ile uyum gösterdiği görülmüş ve sözü edilen bölgelerin benzer tektonik rejimlerin etkisinde olduğu, bununla birlikte, önceki çalışmalarda hesaplanmış Pn anizotropisi doğrultularının, hesaplanan hızlı makaslama doğrultusu ile uyumlu olmaması nedeniyle, bölgedeki üst manto yapısının daha karmaşık olduğu sonucuna varılmıştır. Anahtar Kelimeler: SKS ayrımlanması analizi, sismik anizotropi, Marmara Bölgesi.The seismic anisotropy contains information regarding the fabrics and deformation of deeper parts of the earth (Babuska etal., 1998). In an anisotropic medium, one component of a shear wave travels faster than the orthogonal component. The difference in speed causes the waves to separate; this phenomenon is called shear wave splitting (Savage, 1999). SKS splitting analysis is one of the most widely used methods to determine anisotropy (Silver and Chan, 1991). SKS splitting parameters; fast polarization direction (f) and delay time (dt), provide information about the dominant flow direction and thickness of the anisotropic layer. The study of anisotropy can shed light to the complex tectonic structure (or strain pattern) of the area when evaluated together with whole tectonic and GPS data. In the areas of recent convergence the fast direction of anisotropy generally aligns in the direction of the plate boundary (Vinnik etal., 1992). This correlation suggests that the shortening is the same in the crust and the upper-mantle. In the regions of rifting, direction of mantle flow generally aligns parallel to the extension in the crust. In the stable regions it is likely that combined effect of frozen anisotropy in the lithosphere and recent anisotropy in the asthenosphere are observed. The tectonic regime of Turkey is dominated by different plate motions. The collision of Eurasia and Arabia in the Zagros region is the driving force of west-ward tectonic escape towards the Aegean between a rigid boundary on the north, oceanic crust in the Black Sea and a weak boundary on the south, Aegean subduction zone (Şengör etal., 1985). The escape is mainly along the North and East Anatolian strike-slip faults. The fast shear wave polarization direction obtained from SKS splitting studies can be correlated with the absolute motion of the plates and the study of anisotropy can light up the complex tectonic structure (or strain pattern) of the area. In this study, seismic anisotropic structure of the upper-mantle beneath İstanbul (ISK) broad-band station (KRDAE-NEMC), Marmara Region, is investigated by using SKS splitting analysis. Fifteen earthquakes with magnitude greater than 5.0 occured at epicentral distances between the range of 85° and 120° are selected based on the criteria of existing of clear SKS phases on the records. Splitting correction method of Silver and Chan (1991) can be used for obtaining SKS splitting parameters (f, dt). In this method, analysis window is chosen manually. But calculated parameters are sensitive to the manually selected shear-wave analysis window. Therefore, we used an automated shear wave analysis code (Teanby etal., 2004) to analyse the data. In this code, the analyse window is selected automatically by performing a grid search over different windows to find stable splitting measurements with small error. To stabilize the results and reduce cycle-skipping effects, start of the window should be chosen slightly before the onset of the shear wave. It is also important that over a wide range of different analysis windows splitting parameters are stable to provide robust measurements (Teanby etal., 2004). If anisotropy exist, the particle motion within the window should be elliptical. Also energy should be present in the transverse component of the data. When those conditions are provided, splitting analyse is performed. Splitting parameters are the parameters that correct the effect of the anisotropy. After the correction is applied with obtained splitting parameters, splitting should be corrected which means a linear particle motion instead of elliptical, no energy on the transverse component and no delay time. Following those data processing steps, SKS splitting parameters for the ISK station, from 15 teleseismic earthquakes are obtained. For ISK station fast polarization direction is calculated as 43.7°. This parameter is compared to the one that was obtained from Ankara (ANTO) broad-band station (IRIS-GSN) in Central Anatolia and existing results of Pn anisotropy studies (Al-Lazki etal., 2004) which is sensitive to uppermost mantle anisotropy. Splitting parameters obtained from ISK station exhibit parallelism with those obtained from ANTO station. This suggests that seismic anisotropy under ISK and ANTO are effected by similar tectonic regimes, however, due to the incoherent SKS fast polarization direction (f) and Pn anisotropy directions upper-mantle structure beneath ISK station is suggested to be more complex. Keywords: SKS splitting analyse, seismic anisotropy, Marmara region
Ilgın (Konya) kuzeyindeki metasedimanter ve metavolkanik kayaçların jeolojisi ve jeokimyası
Get PDFThe Afyon-Bolkardağ Zone is one of the metamorphic belts, along with the Tavşanlı Zone, Menderes Massif and Lycian Nappes in western Anatolia, eastern Mediterranea. The study area included by thiz zone is located in the north of Ilgın (Konya-Turkey). Two main metamorphic groups and cover series unconformably overlaid each other from Ilgın of Konya province are reported in this study. From bottom to top, these are: Paleozoic metasedimentary group, Mesozoic metasedimantary and metavolcanic group, Neogene covers and Quaternary alluvium. The Paleozoic group is 1000m in thickness observed particularly in the west and middle part of the study area. This group is derived from the metamorphics of conglomerate, sandstone, siltstone, claystone, limestone and quartzite. Metaconglomerates consist of chert, shale, quartz and green schist fragments in clayey-sandy matrix. Metasandstones are grayish color, grain-supported, well-consolidated and carbonate cemented and bedding is from fine to medium. Phyllites are made up of mainly thin mica flakes and rarely fine-grained quartz and feldspar. Metacherts are thin-bedded, gray in color. Metacarbonates include elongated, flatted calcites, muscovite, chlorite, tourmaline and quartz. Metaconglomerates, at the base of Mesozoic group, purple-pinkish in color pass gradually laterally and vertically into metasandstones. Metasandstones are grayish-reddish-greenish color, mostly 5-30 cm and rarely 10 m in thickness. Metacarbonates are generally dolomitic limestone and dolomite and gray, white and yellow in color. They are in upper levels of Mesozoic group. In this study, we stated that rhyolitic metavolcanics are different from others formerly cited in Ilgın (Konya). These rocks are light-dark gray and green colors. These are mostly metalavas and metatuffs unmapped in scale and thin bedded within schists. The black white alteration surfaces are widespread in the rocks considered lava origin. The foliation is marked in the passing into the schists and muscovites are wieved along foliation plains. The Paleozoic metasandstone and schist samples have high content of SiO2. Na2O values of Paleozoic samples vary from zero to 2.15 % and a higher value of K2O (5.8 %) is found in some samples. The values of high Rb and low Sr in some samples are significant. Schists have 64.2-81.33% SiO2. These values suggest that the Paleozoic group is felsic lithologies and acidic in character. Ba values are in the range of 6-485 ppm. On the other hand, some samples have high Zr values (486 ppm). The high contents of Rb may have resulted from the presence of muscovite in these rocks. Na2O and K2O values are very low whereas Sr values are high in dolomitic metacarbonates. Magma composition changes due to mineral fractionations. K2O, CaO, MgO, Fe2O3 and TiO2 show negative correlations with increasing SiO2 whereas Na2O shows positive correlation. As the SiO2 content increases, the Sr, Ba, Co, Th, Sc and Hf contents decrease and the Rb content increases. However, Cs shows variation. Linear correlations can be explained by fractional crystallizations whereas such unlinear trends as negative and/or positive correlations can be explained by partial alterations and magma mixing in major and trace element diagram. Metavolcanics have 75-80% groundmass and 20-25% phenocrysts. Phenocrysts are quartz, K-feldspar, remnant sanidine and albite. Feldspars occur mostly as K-feldspar (Or 85-97 Ab 3-6 An 0-2). Matrix is composed of microcrystalline quartz, K-feldspar, sericite and rarely muscovite. The metavolcanics have 66-77% SiO2, 5.8-10.6% K2O, 0.08-1.77% Na2O, 12-18% Al2O3, 0.1-0.4% MgO, <1% CaO. This chemical composition suggests that metavolcanics are high-K rocks with acidic character. The Ba contents of some samples reach up to the high levels. Plotting data for metavolcanics in the SiO2 vs. Zr/TiO2 diagram samples fall into the rhyolite field. Metavolcanics are extremely K-rich (7-11 wt. % K2O), calc-alkaline in character and show also strong enrichment in LILE and LREE. Metavolcanics show concave REE pattern with (La/Lu)N:0.87-215.54 and have negative Eu anomalies (Eu/Eu*)N:0.0024-0.23. One sample, 3.92, from Paleozoic unit in Ilgın (Konya) region, yielded muscovite age of 96.9±1.4 Ma, whilst three samples, 4.10, 3.109 and TSD1, yielded muscovite ages of 70.2±1.0Ma, 65.6±1.0Ma and 64.4±1.0Ma, implying polyphase metamorphism in this region and the last phase was in Upper Cretaceous-Lower Paleocene. Three samples, 3.37, 3.122 and 2.5 from metavolcanics yielded whole rock ages of 60.4±0.9Ma, 62.6±0.9Ma and 64±2.0Ma. Keywords: Afyon-Bolkardağ Zone, geochemistry, geochronology, high-K metavolcanics, Ilgın-Konya, metamorphism.Ilgın bölgesinde (Konya); Paleozoyik metasedimanterler, bunlar üzerinde uyumsuz Mesozoyik metasedimanterler ve metavolkanikler ve tüm bunları açısal uyumsuzlukla örten Neojen çökeller ve alüvyon yer alır. Çalışma alanının genellikle batı ve orta kesiminde yaygın olarak izlenen Paleozoyik topluluğun kalınlığı 1000 m’ye kadar ulaşır ve çakıltaşı, kumtaşı, silttaşı, kiltaşı, kireçtaşı ve kuvarsitlerin metamorfik türevlerinden oluşur. Mesozoyik topluluk tabanda metakonglomera ile başlayıp üste doğru daha ince taneli ve nihayet karbonatlardan oluşan metasedimanterler ile bunlar arasındaki metalavlar ve metatüflerden oluşmaktadırlar. Mesozoik topluluk içindeki metavolkanik kayalar, yüksek-K’lu riyolitlerin düşük derecede metamorfizmaya uğramış lav ve tüfleridir. Bunların mineral bileşimi; %75-80 matriks (ince taneli kuvars, K-feldspat ve serizit) ile %20-25 oranındaki fenokristallerden (kuvars, K-feldspat,Or94-97, Ab2-6An0-0.74,kalıntı sanidin ve albit) oluşur. Matrikste serizitleşme, feldspatlaşma ve silisleşme belirgindir, birincil doku ayırt edilebilmektedir. Yüksek-K’ lu metavolkanikler (K2O: % 7-11) kalkalkali karakterlidirler. Nadir toprak element dağılımı; (La/Lu)N: 0.87-215.54 ve (Eu/Eu*)N: 0.0024-0.23 aralığını (negatif Eu anomalisi) verir. Paleozoik metamorfik grupta kloritoid ve stilpnomelanın varlığı ve Mesozoik metamorfik grupta bu minerallerin olmayışı metamorfizma derecesinin alttan üste doğru azaldığını gösterir. Muskovit K-Ar değerlerine göre (Paleozoyik metamorfik grup örneği: 96.9±1.4My, Mesozoyik metamorfik grup örnekleri; 70.2±1.0My, 65.6±1.0My ve 64.4±1.0My) bölge çok evreli metamorfizmanın etkisinde kalmış ve metamorfizmanın son evresi Üst Kretase-Alt Paleosen’de gelişmiştir. Metavolkanik tüm kaya K-Ar değerleri 60.4±0.9My, 62.6±0.9My ve 64.1±2.0My olarak elde edilmiştir. Anahtar Kelimeler: Afyon-Bolkardağ Zonu, jeokronoloji, yüksek-K metavolkanikler, Ilgın-Konya, metamorfizma, Turkey
The geological and petrological properties of volcanic rocks in Çanakkale-Çan area in the northwest Anatolia and investigation of evolution of volcanism
Get PDFİnceleme alanı KB Anadolu’da, Çanakkale-Çan arasında KB Anadolu’nun metamorfik temel kayaçları, magmatik ve çökel kayaçların bir arada bulunduğu bir bölge konumundadır. Bölgedeki istifin temelini Üst Kretase-Alt Paleosen yaşlı Çamlıca metamorfikleri oluşturmaktadır. İnceleme alanında Üst Eosen-Alt Oligosenden itibaren kalkalkalen karakterli yaygın bir magmatik faaliyet Dededağ volkaniklerinin andezitik ve riyolitik karakterli lav ve bunların piroklastikleri ile başlayıp andezit, riyolit lav akıntılarıyla devam etmektedir. Dededağ formasyonu kalkalkalen ve metaluminus özellik göstermekte ve volkanik yay bileşeni ve tüketilen levha sınırı alanında yer almaktadır. Alt-Orta Miyosen, andezitik ve bazaltik kayaçlardan oluşan Kirazlı volkanikleri ve Çamyayla plütonu ile temsil edilir. Kirazlı formasyonun da yay bileşeni ve tüketilen levha sınırı volkanik kayaçları alanında yer aldığı görülür. Çamyayla plütonu sığ sokulumlu olup granit, granodiyorit, kuvars diyorit bileşimlidir. Çamyayla Plütonu çevresinde aktinolit hornfels ve kuvars-alkali feldspat hornfels fasiyesin de kontak metamorfizma zonu gelişmiştir. Plütonik kayaçlar kalkalkalen nitelikte olup, metaluminus özelliği göstermektedir. Ana ve iz elementlerin kullanıldığı diyagramların değerlendirilmesi sonucunda Çamyayla plütonunun yitim zonu bileşeni içerdiği belirlenmiştir. Üst Miyosen’de Caferler trakibazaltı gelişmiştir. Bu birim kırık zonları boyunca yerleşmiştir. Üst Miyosen dönemine kadarki süreçte gelişmiş olan magmatizma, Ege bölgesinin magmatizmasıyla uyumlu ve onun bir parçasını temsil ettiği kalkalkalen nitelikli, üst mantodan gelişen, kabukta kirlenen bu magmatizmadır. Dalma-batma kökenli olduğu ortaya konulmuştur. Bölgede Geç Miyosen’den itibaren başlayan yeni tektonik rejim altında ise yeni bir magmatizmanın oluştuğu ve o dönemde de rift tipi bazaltların geliştiği belirlenmiştir. Anahtar Kelimeler: KB Anadolu, volkanik kayaçlar, plüton.The study area between Çanakkale and Çan is located in Northwest Anatolia where metamorphic, igneous and sedimentary rocks all together crop out. The Çamlıca Metamorphics, form the basement. In the study area, magmatic activity began during late Eocene-Early Oligocene period and produced andesitic lavas and pyroclastic rocks (Dededağ volcanic). It was followed by andesitic and basaltic andesitic during the Early Miocene period (Kirazlı volcanic). Partly contemporaneously with the developments of these volcanic associations granitic intrusive rocks were emplaced to the subvolcanic depths (Çamyayla Pluton). A contact metamorphic aureole formed around the pluton displaying actinolite-hornfels mineral assemblage. During the late Miocene the tectonic regime charged; a N-S extension began. The present E-W trending grabens began to developed. Basaltic lavas were erupted (Caferler Basalt) along the graben-bounding faults. The early phases of volcanic products were generated. In the upper mantle and geochemically enriched by the crustal components during its ascent. These volcanic rocks are similar to the subduction-induced lavas. In upper Miocene the Caferler trahy-basalts developed and located along the fracture zone. Magmatism, calc-alkaline characteristics, developed from upper-mantle and contaminated by crust is originated from subduction zone. The study area, its location in Biga peninsula, located in the North of Sakarya continent and Ezine zone which are Turkey’s tectonic units. Sakarya continent along E-W, covered by Intra-Pontid zone in the North and Izmir-Ankara ofiyolit zone formed as a result of collision of Sakarya continent and Torid-Anatolid platform after Neo-Tethys ocean closed. There have been numerous studies related to geological events during Cretase-Oligocene in the NW Anatolia. As a result of these studies, it is known that Neo-Tethys ocean start to subducted towards North and closed, in the Cretase. N-S collision developed in the region continued between Upper Cretase and Miocene and continental crust shortened and thickened. In the study area Dededağ formation, investigated as lower volcanic unit, continued Upper Eocene-Oligocene. After Upper Eocene the region became terrestrial environment. Granitic intrusions associated with thickened and shortened continental crust located. In the study area Çamyayla pluton which formed with upper part of Dededağ volcanic as one inside the other, intruse into the Akpınar metamorphic rocks and cause contact metamorphism. Dededağ volcanic rocks resemble geochemical characteristics with Çamyayla pluton, showed calc-alkalen metaluminus features. However, two fresh ryholite samples, plotted into the peraluminus region, suggest that Lower Eocene-Upper Oligocene age volcanism’s later stage may have been contaminated by the continental crust. The data obtained from major and trace elements diagrams showed volcanic arc and consumed continental border. Kirazlı formation lied uncomfortable on the Dededağ formation form middle volcanic units. Lower-Middle Miocene age Kirazlı formation represents middle-basic characteristics. In the Dededağ volcanic Ta/Th-Ta diagram, it is seen that AFC could be important where as in the Kirazlı volcanic assimilation with volcanic crystallization could be important. Volcanism developed until late Eocene after Paleotectonics units collision and became unit (Late Cretase-Middle Eocene) in the Aegean subduction zone. During subduction, it moved to south and volcanic side also moved along with it. The study area, represent the subduction zone associated magmatism aged between late Oligocene-Early Miocene. In the study area upper volcanic units outcropped during Late Miocene. The unit made of ryholite lava and pyroclastics developed one inside the other with Çan formation. During upper Miocene the volcanism changed its characteristics due to N-S extension regime causing thinning the continental litospher and alkaline volcanism developed. Starting with late Miocene West Anatolia-Aegean continental crust which are shortened-thickened started to collapse and graben formed. During this time, volcanism originated in the subduction zone left their place to volcanism originated in the north-south extension system. This volcanism is alkalen in character and basalt is widespread. Caferler basalt is different from the other basaltic rocks in the study area and contains large and group olivine. Caferler basalts represent basaltic-traciandesitic, tracibasalt characteristics. Keywords: NW Anatolia, volcanic rocks, pluton
Modeling drying curves and temperature profiles of microwave-assisted convective drying of grapes
Get PDFBu çalışmada, Türkiye'nin önemli ihraç ürünlerinden olan üzümün kuruması esnasında kararmaya neden olan Polifenol Oksidaz enziminin, çocuklarda ve yaşlılarda astım, isilik ve mide rahatsızlıklarına neden olabilen sülfit kullanılmadan inaktive edilmesi ve aynı zamanda da kuruma hızının arttırılması amaçlanmıştır. Mikrodalga yardımlı konvektif kurutma, konvansiyonel kurutma yöntemlerine göre daha hızlı olduğundan ve gıda maddesinde bulunan dipolar su molekülleri ile etkileşebilmesinden dolayı etkin bir kurutma işlemine olanak sağlamaktadır. Gıda içindeki sıcaklık artışının modellenmesi mikrodalga ısıtma ve kurutma işleminin kontrolü açısından önem arz etmektedir. Kurutma hızını daha da arttırmak ve iyi bir son ürün elde edebilmek amacıyla üzümler kurutma işleminden önce 40°C sıcaklığındaki etil oleat ve potasyum karbonat içeren çözelti içine 3 dakika süreyle daldırılmış veya 90°C’deki buharla 140 saniye süreyle haşlanarak önişlenmişlerdir. Üzümler önişlemlerden sonra mikrodalga yardımlı konvektif kurutucuda 0.25 W/g başlangıç mikrodalga güç oranı ve 60°C sıcaklığında ortalama 1.8 m/s hızındaki hava ile kurutulmuşlardır. Matlab programının Eğri Yaklaştırma (CFT) araç kutusu kullanılarak kuruma eğrileri literatürdeki ince tabaka modelleri ile tanımlanmışlardır. Kuruma esnasındaki sıcaklık değişimleri fiber optik prob kullanılarak ölçülmüş ve Matlab programının Kısmi Diferansiyel Denklem (PDE) araç kutusu kullanılarak matematiksel olarak modellenmiş ve simüle edilmiştir. Matematiksel modelde mikrodalga enerjisi hacimsel ısı üretim kaynağı olarak kabul edilmiş ve kuruma esnasında meydana gelen ve ince tabaka modelleriyle hesaplanan nem kaybı, evaporatif ısı kaybı olarak modele dahil edilmiştir. Sonuçları literatürdeki çalışmalar ile karşılaştırdığımızda, mühendislik açısından gerekli yakınsaklık sağladığı gözlenmiştir. Anahtar Kelimeler: Mikrodalga kurutma, üzüm, modelleme, Matlab, eğri yaklaştırma.Raisin is an important export product of Turkey and darkens during drying due to the enzyme Polyphenol Oxidase (PPO). To prevent browning reactions, these products are sulfited. Ingestion of sulfites can lead to asthmatic attacks, rashes and abdominal upset especially for elderly people and children. For these reasons sulfites are either prohibited or subject to very low limits in USA. Thompson seedless grapes were used in this study. Grapes were dipped into 2% ethyl oleate (v/v) and 5% potassium carbonate solution (m/v) at 40°C for 3 minutes and were blanched with steam at 90°C for 140 seconds. The aims of these pretreatments were to accelerate drying rate and to inactivate PPO without the use of sulphur dioxide. Pretreated grapes were dried in a microwave-assisted convective dryer. Center temperature profile of grapes were obtained using a fiber optic probe. It was observed that 0.25 W/g initial power ratio combined with 60°C convective air produced better end-product thus in this study drying curves and temperature profiles were modeled at this selected condition. The thin layer drying models were used to describe the drying curves of both pretreated and untreated grapes. Using curve fitting tool (CFT) of Matlab software, non-linear regression analysis were performed to thin layer models. Regression coefficient (R2), Sum of Squares Due to Error (SSE) and Root Mean Square Error (RMSE) were adopted to evaluate the goodness of fit in each model. Among the thin layer models, drying curves of microwave-assisted drying of both untreated and pretreated grapes at 0.25 W/g initial power ratio and 60°C convective air temperature could be accurately described by all of the applied thin-layer models. For all cases the R2 were greater than 0.97 and SSE and RMSE were close to zero. In order to compare the moisture loss with time, derivative of logarithmic model with respect to time was taken. It was found that moisture loss of untreated and chemically dipped grapes could be considered as same however, moisture loss of steam blanched grapes were 2.30 times higher than untreated and chemically dipped grapes until 300 minutes drying. It is critical to have knowledge of dielectric properties, relative dielectric constant and relative dielectric loss factor, of materials which are the most important physical properties in microwave heating. In this study dielectric properties of grapes were calculated using descriptive equations for fruits and vegetables. In these equations dielectric properties of materials were related with temperature and moisture content. Within the temperature range of this study, temperature had negligible effect on the values of dielectric properties of grapes. Thus during microwave-assisted convective drying of grapes, only moisture dependent dielectric properties were taken into consideration. Electric field in the grapes was calculated through calorimetry. Since the penetration depth of microwave energy was less than radius of grape, integral average of electric field within the grape was calculated. The thermophysical properties, density, specific heat and heat conduction coefficient of grapes were also calculated using descriptive equations. The results were in close agreement with the literature. Experimental center temperature of grapes was modeled using a one dimensional heat equation which uses microwave energy as a heat generation source term. The main assumptions to solve this equation were that the initial temperature and moisture content of grapes were uniform, both heat and moisture flows in radial direction and heat losses due to radiation were negligible. For simulations Partial Differential Equation Toolbox of Matlab was used. Generic Scalar equation type was selected and the partial differential equation was specified to be parabolic type. Since Matlab requires boundary conditions to be specified to solve the time and space dependent differential equation, Neumann boundary condition was selected due to constant heat flux provided by convective air with a velocity of 1.8 m/s and temperature at 60°C. Since Thompson seedless grapes could be approximated to cylinders, both the boundary conditions and the differential equation were expressed in cylindrical coordinates. It was found that the maximum difference between experimental and simulation values were 4°C was during initial heating up period. However, after then the difference was less than 1°C. Since the phase changes of grapes were not incorporated into the model, sudden increase in temperature below 56% moisture content could not be predicted by the proposed simulation model. Keywords: Microwave drying, grapes, modeling, Matlab, curve fitting
Construction of new rational approximants based on transformational high dimensional model representation and their applications on LSI systems
Get PDFOransal yaklaştırım yöntemlerinin, tek veya çok değişkenli fonksiyonlardaki doğrusal olmama durumlarının veya tekilliklerin üstesinden gelmede kullanılan en etkin ve oluşturulması en kolay yaklaştırım yöntemleri olduğu söylenebilir. Bu yöntemler, çok değişkenli, doğrusal öteleme altında değişmeyen sistemlerdeki (ing: Multidimensional Linear Shift Invariant-LSI recursive systems) model indirgeme uygulamalarında, çok düzeyli birleştiricilerdeki (ing: multiplexer models) paket kayıp olasılıklarının hesaplanmasında ve üç boyutlu şekilleri yeniden oluşturmada (ing: shape reconstruction) kullanılırlar. Bu çalışmada, çok değişkenli, yeni bir oransal yaklaştırım yöntemi geliştirilmiş, yöntemin özellikleri, günümüzde oransal yaklaştırım yöntemlerinin en başında gelen Padé yaklaştırım yöntemi ile karşılaştırmalar yaparak tartışılmıştır. Burada sunulan oransal yaklaştırım çizemi, YBMG’nde (Yüksek Boyutlu Model Gösterilimi) yapılan kesmelere dayanır. YBMG, analitik yapısı bilinen çok değişkenli fonksiyonları daha az değişken içeren bir takım fonksiyonların toplamı olarak yaklaştırmaya dayanan ve son 15 yılda geliştirilen bir yaklaştırım yöntemidir. Çalışmada, yaklaştırımın niteliğini arttırmak amacı ile yöntemin yapısına bir takım esneklikler katılmıştır. YBMG, asıl fonksiyon yerine fonksiyonun birinci derece dönüşüm altındaki görüntüsüne uygulanmıştır. Bu da bize yaklaştırıma fazladan esneklik katabilme olanağını vermiştir. YBMG aracılığı ile elde edilen bu yeni yaklaştırım yönteminin fiziksel problemlerdeki davranışını gözlemlemek amacı ile, yöntem doğrusal öteleme altında değişmeyen, çok değişkenli sistemlere (LSI) uygulanmıştır. Bunun dışında, tek değişkenli bir yapay fonksiyon örneği de, yöntemin tek değişkenli fonksiyonlardaki etkinliğini incelemek için verilmiştir. Sonuçlar, tek veya çok değişkenli bir fonksiyonu Padé oransal yaklaştırım yöntemine göre daha geniş bir aralıkta yaklaştırabildiğimizi göstermektedir. Anahtar Kelimeler: Yüksek boyutlu model gösterilimi, oransal yaklaştırım, çok değişkenli analiz.There are plenty of methods to approximate a multivariate function arising from different concepts. Some of them are based on the truncation of infinite series like Taylor series or orthogonal expansions. These do not explicitly reflect the singularities of the function to be approximated. One of the infinite series explicitly showing singularities is the Laurent series, which include finite or infinite simple fractions to represent polar singularities. Since any rational function can be uniquely represented by a Laurent series, it is common practice to use rational approximants for approximating the functions to explicitly reflect all polar singularities. Padé approximants are perhaps the most frequently used ones in this category. Functions having strong singularities like branch points or essential singularities need special attention and can be approximated by using more specific techniques. Rational approximation techniques are perhaps the leading and easiest ones used to handle nonlinearities or singularities in the approximation of univariate or multivariate functions in science and engineering. They can be used in model-reduction of multidimensional Linear Shift Invariant (LSI) recursive systems, computing packet loss probabilities in multiplexer models, and shape reconstruction. In this work, we construct a new multivariate rational approximation method and discuss its advantages and disadvantages by comparing with the Padé technique, which is at the moment the leading rational approximation technique. The rational approximation scheme proposed here is formulated by using HDMR (High Dimensional Model Representation) truncations. HDMR has been developed in the last 15 years to approximate multivariate functions by a sum of less variate functions. Here, we insert certain flexibilities into the approximation, in order to improve its quality. The most general class of this type of HDMR is called "Transformational High Dimensional Model Representation" (THDMR). In THDMR, the image of the original multivariate function is approximated by a sum of less variate functions. The coefficients of the transformation are considered as optimization parameters, which make the error of the method as small as possible. In this work, a first degree polynomial structure is used as THDMR's operator and the coefficients of this first degree transformation are assumed to be varying with independent variables. This is for giving flexibilities to the transformation and fixing them to approximate the HDMR expansion optimally. Although THDMR has a more general structure than we used here, we chose to work with the first degree polynomial structure for unique invertibility. Once an approximation for this first order polynomial structure constructed by HDMR method, the approximation for the original function can be obtained by inverting the polynomial structure. The rational structure of the method comes from this special choice of THDMR operator. The univariate and bivariate results are quite impressive and imply that we can approximate a multivariate function over a quite larger interval when compared with the Padé method. This is caused by the fact that these two methods involve different strategies of extracting information from the original function. In THDMR method, the integral of the original function is computed over a specified interval to extract information from it, while Padé approximation method uses the derivatives of the function in a specific point. So THDMR method approximates the function more uniformly compared with Padé approximation technique which exhibits a local character. Moreover, the quality of the approximation can be improved by changing the integration intervals in THDMR. An important defect of the rational approximation techniques is that they can produce some poles over the focused interval, although the original function has no singularity over the same interval at all. The singularity problem exists also in THDMR method. However, in THDMR, in order to obtain the rational approximant, certain integrals are needed to be computed and the location of the possible poles of the approximant can be altered by changing the interval of the integration. This facility of changing the locations of the poles with the integration interval makes the method attractive and efficient. In order to see the behavior of the method on physical problems, we have applied it on LSI systems to reduce the system. The transfer function of the LSI system has been approximated by THDMR and Padé methods. The results show that, the newly developed THDMR method can be used on LSI systems with high level approximation quality. Keywords: High dimensional model representation, rational approximation, multivariate analysis
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