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Hata tanıma ve hata toleranslı kontrol: Destek vektörü makineleri yaklaşımı
Get PDFBecause of increasing need for reliability, safety, maintainability and survivability in technological systems, fault tolerant control system has become extremely important. Fault tolerant control systems have been developed to overcome some weaknesses of the conventional feedback control design, such as instability and unsatisfactory performance in the faulty cases. In complex systems such as aircrafts, nuclear power plants, chemical plants etc., the results of a minor fault in the system can be destructive. Therefore, it is necessary to design control systems that are able to tolerate potential faults in these systems. A control system with this kind of fault tolerance capability is defined as fault tolerant control system. A fault tolerant control system is a closed-loop control system which can tolerate malfunctions while maintaining desirable performance and stability properties. A typical active fault tolerant control system includes three sub-systems: reconfigurable controller, fault detection and diagnosis unit and decision supervisor unit. The reconfigurable controller is placed in control loop, instead of regular controller in traditional closed-loop control system. Since the real time toleration of faults can only be achieved if the control system has an automatic reconfiguration mechanism. This reconfiguration is generally activated after a fault has been detected and isolated. A fault detection and diagnosis system is a unit that obtains the occurrence of faults and determines their features in terms of type, location, size and/or time. The decision supervisor activates reconfiguration action in response, which can be pre-determined for each fault or obtained from real time analysis and optimisation. In active fault tolerant control systems, reconfiguration mechanism can be classified as on-line controller selection and on-line controller calculation techniques. In the on-line controller selection approach, the controllers associated with presumed faulty conditions are computed in an off-line manner in the design stage and they are selected in an on-line manner based on the real time information from fault detection and diagnosis algorithm. In the on-line controller calculation approach, the controller parameters are calculated in an on-line manner after the occurrence of fault. In this study, an active fault tolerant control technique, support vector machines based direct fault tolerant control system, is presented. In general, reconfiguration mechanism of a fault tolerant control system utilizes the information from fault detection and diagnosis unit at the decision stage. In the presented method, reconfiguration mechanism and diagnosis unit work independently. Both of them use only real time system outputs. A powerful and fast learning algorithm is needed for this purpose. Support vector machines is one of the most popular intelligent machine learning tools. They have become a very good alternative of neural networks with their superior generalization capacity, classification, regression and modeling performance. In this paper, support vector regression machines have been used in fault detection and diagnosis process and also in reconfigurable controller unit. PID type controllers have been used in reconfiguration sub-system. The PID coefficients of faulty and un-faulty cases to be used in training stage are obtained by genetic algorithm approach in an off-line manner. In reconfiguration mechanism, for each PID coefficient one support vector regression machine is set up. Faulty and un-faulty system outputs are collected for different input signals. In training stage, faulty system outputs and corresponding PID parameters are used as support vector regression machines' inputs and outputs, respectively. Thus the training phase of support vector machines is completed in an off-line manner. After completing the training phase, system is run for the reference input signal. The outputs of system are sent to decision unit periodically. Three of support vector regression machines are simultaneously evaluated the data sent by the system, and produce coefficients of the PID controller. The controller of which its coefficients are reconfigured, starts to work to maintain system performance in an on-line manner. In order to determine the type of fault, a similar process is exploited using one support vector regression machine. In training phase, inputs of this support vector regression machine are faulty and un-faulty system outputs but outputs are the features of the faults. This fault diagnosis unit runs parallel with intelligent fault tolerant controller. The performance of this knowledge based fault diagnosis and active fault tolerant control methods is illustrated on simulation example involving a two-tank water level control system under faulty conditions. Keywords: Fault tolerant control, fault detection and diagnosis, support vector machines, PID controllers, two tank water level system.Geleneksel bir geri-beslemeli kontrol sistemi, bazı arıza durumlarında istenilen başarımı veya kararlılığı sağlamayabilir. Bu tür zayıflıkların üstesinden gelebilmek için, bir yandan istenen kararlılık ve performans özelliklerini sağlayacak bir yandan da elemanların kayıplarını telafi edecek hata toleranslı kontrol tasarım yöntemleri geliştirilmiştir. Geleneksel hata toleranslı kontrol sistemlerinde önce olası hatalar tespit edilir, sonra kararlılığı ve kabul edilebilen bir başarımı sağlayacak yeniden düzenlemeyi gerçekleştirmesi için akıllı bir karar mekanizması devreye girer. Bununla, tespit edilmiş duruma en uygun olan önceden tasarlanmış kontrolör devreye sokulur. Bu çalışmada önerilen destek vektörü makineleri ile doğrudan hata toleranslı kontrol yöntemi, hatanın etkisini giderecek düzenleme yapması için, hata bulma ve tanıma aşamalarına gereksinim duymaz. Bu çalışmada amaç, sistemde oluşabilecek hatanın etkisini sadece sistem çıkışından alınan verilerle çevrim-içi çalışan bir düzenleme ile ortadan kaldırmaktır Bu yöntemde bir akıllı kontrolör sistemi kurulur. Çevrim-dışı gerçekleştirilen eğitimde kullanılacak hatalı durumlara ilişkin kontrolör katsayıları genetik algoritma arama yöntemi ile tespit edilir. PID tipi kontrolör katsayılarının her biri için kurulan destek vektörü bağlanım makinesi, toplanan hatalı ve hatasız sistem çıkışları giriş ve ilgili katsayılar çıkış olacak şekilde eğitilir. Sistem çalışırken belli aralıklarla alınan sistem cevabı karar mekanizması tarafından değerlendirilir. Kontrolör katsayıları, sistem cevabına göre çevrim-içi ayarlanır ve sistemin istenen davranışa götürülmesi sağlanır. Hata tanıma birimi, çıkışı hatanın türü olan bir destek vektörü makinesi ile benzer şekilde oluşturulur ve paralel çalıştırılır. Yöntemin, çift tanklı sıvı seviye sisteminde uygulaması yapılmıştır. Anahtar Kelimeler: Hata toleranslı kontrol, hata bulma ve tanıma, destek vektörü makineleri, PID kontrolör, çift tanklı sıvı seviye sistemi
Effect of shading devices on external pressure coefficients' of windvard surfaces of buildings
Get PDFBinaların pasif olarak en etkin biçimde soğutulması amaçlandığında; güneş ışınımı engeli olarak tasarlanacak kontrol elemanlarının (GE), tasarım aşamasında rüzgar etkileri bakımından irdelenerek performanslarının optimize edilmesi zorunludur. Yukarıdaki gerekçeye dayanarak yapılacak çalışmanın amacı; özellikle rüzgar konusunda sayısal yöntemler yeterli olamayacağından, GE’lerin basınç ve taşınım katsayıları üzerindeki etkilerinin rüzgar tünelinde deneysel yolla ortaya konmasıdır. GE’lerin cepheye paralel, dikey ve 45 derece açılı konumlandırılışlarıyla ana üç seçenek, kanatlarının 0 – 45 - 90' kanat açılarıyla oluşturulmuş almaşıklar ve referans (BOŞ) durum da dahil olmak üzere toplam 19 adet farklı durum üretilmiştir. Seçenek ve almaşıkların her birinde tünel içi hızı (GH) 2.5 ms-1, 5.0 ms-1 ve 8.3 ms-1’de rüzgar üstü yüzeyde basınç ölçümleri yapılmıştır. Bina yüzeyinde oluşan basınç katsayılarının (Cp) GE seçeneklerine bağlı olarak referans duruma (BOŞ) göre ne kadar farklılık gösterdiği incelendiğinde; % 95 güven aralığında, en dikkate değer fark referans durum ile (GE- CP- YK 0) yatay kanatlardan oluşan gölgeleme elemanının cepheye paralel konumlandırıldığı, 0 derece kanat açısında (t = 4.745, p =.0000 düzeyinde) ortaya çıkmıştır. Yapılan çalışmanın sonuçları pasif soğutma sisteminde rüzgar basıncıyla iç mekanlardaki hava hareketi hızının uygun düzeylerde sağlanıp sağlanamayacağının kestirilebilmesinde kullanılabilecektir. BOŞ durumda orta aksta cephenin tümünde Cp ort = ~ 0.80 düzeyinde elde edilen basınç katsayısı (Cp) değeri birçok ülkenin rüzgar yüklerine ilişkin yönetmeliklerine uyum göstermesine rağmen zemine yakın noktalarda mevcut benzer çalışmalardan ~ %10 daha büyük miktarlar ortaya koymuştur. Anahtar Kelimeler: Gölgeleme elemanları, basınç katsayısı dağılımı, doğal havalandırma, pasif soğutma.Solar shading devices prohibit the passage of direct component of solar radiation at the same time decrease the chilling effect of winds on buildings by forming insulative air pockets in summer season. External solar shading devices vary as a function building crust orientation. In other words they should be designed as auxiliary architectural parts. These parts may be manufactured from materials such as glass, wood, plastic, concrete or metal. Typologically their form resembles shield forms which are either parallel or perpendicular to the building façade. Wind imposed pressure variations have major influence on building thermal comfort through temperature, humidity and air circulation speed. These entities vary as a function of wind direction, wind speed, building orientation, roof and façade shapes, building height and openings on winward and leeward façades. Air mass flow rate that passes through the building may be calculated as a function of average inlet and outlet pressures. In order to obtain the effect of solar shading devices on the wind pressure field over the building surface, an experimental campaign is conducted in a wind tunnel which has a test cross section of 1x1 meter. The 4 mm thick Plexiglas building model which is 50 cm. in width, 30 cm in height and 50 cm in depth simulates 5x3x5 m full scale building forming one zone. Solar shading devices are made of aluminum and of two type wings that are placed parallel to border longitudinal or transversal. The wings make 0, 45 and 90 degrees with the device plane. The position of the shading devices that holds the wings together also makes 0, 45 and 90 degrees with respect to the vertical windward façade of the model. Thus, including the baseline - situation unless shading device is mounted - case, 19 different configurations; are investigated throughout the campaign. There are a total number of 105 pressure measurement points clustered around the edges on the windward face of the model. The measurements were made at 2.5 m/s, 5 m/s and 8.3 m/s average wind speeds. For the case in which solar shading devices are not attached to the façade, the Cp distributions stay in a very narrow band no matter what the wind tunnel speed is. The minimum Cp values are recorded as 0.42, 0.38 and 0.40 for the three speeds: 2.5, 5.0 and 8.3 m/s respectively. The maximum difference between the Cp values happens to be 0.04. The pressure coefficients (Cp) data obtained for different configurations of shading devices are compared with the baseline configuration by Paired Samples Test. They are found significant difference in 95% confidence level, between basline case (BOS ) and configuration that is the shading device parallel to building surface and its wings closed (they make 0 degree with respect to the self plane ) (GE-CP-YK 0 ). The average Cp value along the central axis (Cpave ~ 0.80) obtained for basline case (BOS) is in good agreement with wind load regulations of many other countries. According to the positioning and shading intensity of opaque shading devices on the windward face, the Cp values vary between 130 % and 40% with the respect to baseline case. The correlation coefficients obtained along the C1 axis are calculated as 0.74 and 0.84 for the horizontal and vertical wing configurations respectively. The measurement points corresponding to the opening on the windward face give an average correlation coefficient of 0.73 for all configurations. The effect of Solar shading devices on building façade pressure coefficient distribution has been considered only by a few numbers of researchers in the field. Therefore, excluding the baseline case, the results obtained in the present investigation are original data introduced to the building aerodynamics field. Air mass flow rate that passes through the building may be calculated as a function of average inlet and outlet pressures. In order to assess the usage of the results in the design of natural ventilation systems and cooling load calculations, different pressure and velocity measurement programs are being undertaken. Keywords: Shading devices, forced convection heat transfer, wind pressure distribution, natural ventilation, passive cooling, natural climatisation.
Bankacılıkta operasyonel risk ölçüm modellerinin Türk bankacılık sektöründe faaliyet gösteren bir bankaya uygulanması
Get PDFThe risks that the banks incur are known as credit and market risks. However in recent years by the occurance of financial crises resulting from the complexity of the developments in the financial products and services; the banking sectors realised the reality of operational risks. Operational risk is basicly defined as all the risks other than credit and market risks. However in recent years the definitions for operational risk is updated. The Basel Committee's definition for operational risk is "the loss resulting from inadequate or failed internal processes, people, systems or from external events". In accordance with the Committee's definition the factors resulting operational risk are grouped in four as human, system, processes and external factors. By the official announcement of Basel II in June 2004, measuring and managing operational risk and including in the banks'capital adequacy computations became one of the most popular subjects in banking sectors. In order to manage operational risks effectively, banks are first recommended to define and classify their operational risk factors. Then it will be possible to measure the effect of each factor and calculate the required capital to minimize the effect of the risk. This paper presents the factors causing operational losses and examines the approaches for calculating capital requirements of operational risk using real data of a bank from Turkish banking sector. Keywords: Operational risk, basic indicator approach, standardised approach, alternative standardised approach, advanced measurement approach.Piyasalarda sunulan ürün ve hizmetlerin gelişmesi ve daha karmaşık hale gelmesiyle ortaya çıkan finansal skandallar sonucu operasyonel riskin bankalar için önemli boyutu anlaşılmaya başlanmıştır. Operasyonel risk genel olarak kredi ve piyasa riski dışında kalan tüm riskler olarak ifade edilmiştir. Basel II düzenlemesinin Haziran 2004 tarihinde yayınlanmasıyla birlikte, bankacılıkta operasyonel risklerin ölçümü ve sermaye yeterliliği oranına dâhil edilmesi konusu daha güncel hale gelmiştir. Bu çalışma, operasyonel riskleri oluşturan faktörleri sınıflandırıp, örnekler yardımıyla açıkladıktan sonra, operasyonel risk için sermaye gereksinimi hesaplama yöntemlerinin bankalar tarafından nasıl uygulanabileceğini sektörde faaliyet gösteren bir bankanın gerçek verilerini kullanarak anlatmaktadır. Anahtar Kelimeler: Operasyonel risk, temel gösterge yaklaşımı, standart yaklaşım, alternatif standart yaklaşım, gelişmiş ölçüm yaklaşımı
Piyano eğitiminde çözümleme destekli çalışma metodu ve uygulanışı
Get PDFIt is quite possible that the current piano lessons today can be more analytical. The article will show some ways to add an analytical dimension to our "traditional" approach considering piano practice and teaching by developing specific skills such as spontaneous score reading, harmonization and improvisation. Moreover, we will see how these devices are linked through the common ground of creative thought and experimentation. Developing a fine ear, reading at sight, harmonizing, improvising or understanding the inner workings of the musical language have not always been among the top priorities of the music education system. Most of the 19th-century teaching never got too far into exercising the minds of young students as well as fingers. One could describe the various roles that keyboard players have taken over throughout history, since they have always been socially relevant and useful. An individual could possibly have worn several hats he could be a performer, composer, improviser, accompanist, coach, technician and tuner, public figure in a cultural position, philosopher, researcher and educator. In short, keyboard playing used to be a more functional activity. There was a time when composition and improvisation were taught through the keyboard or more accurately, keyboard studies were the natural road to achieve compositional and improvisational success. Looking from today?s point of view, it is quite possible that a pedagogical approach can be rebuilt that is more dependent on analytical factors. This would save time as well as limit the number of mistakes in the first approach to the piece since analytical approach involves processes that allow for spontaneous reaction to the matter at hand which is one of the best memorization and learning approaches. There seems to be a few approaches possible- first of which is to accept the traditional methods fully and repair the faults produced through their application. The second approach involves a total denial of the current system. A third and intermediate approach is to get into the process of education, factors that have not been fully utilized before. Those basically involve harmonic and formal analysis, mnemonic techniques where mnemo-techni here basically means the involvement of secondary elements that come from auditory, visual or physical (touching) realms for the memorization of a list data. The pianists are the lucky inheritors of a big, still expanding canon of repertoire. This repertoire includes a wealth of solo and chamber music, plus a vast vocal and instrumental literature that brings the piano forth as the most capable and perfectionist accompanying device. Quite naturally, both teachers and students are enthusiastic to explore at least a significant part of that body of literature. As a result, repertoire and instrumental technique have historically absorbed much (if not all) of both instructional time and individual practice. The tendency has been to stress dexterity, resilience and speed, often sacrificing the possibility of a more functional and intelligent approach to piano playing. Through the methodic approach of learning and deciphering that is offered in this article, it is possible that the student could consider learning the musical score using a more spontaneous approach, as well as being creative and flexible in the improvement process while working on the piece. The abilities that are targeted to be enhanced through this type of study are most specifically improvement in terms of improvisation; being able to find creative connections among activities such as playing by ear, transposing or generating harmony for a melody on the spot. The examples used in this article have been restructured for the use of such an education purpose, and are used as a helping device and present alternative routes. The analytical definitions regarding the changes on the harmonization and deciphering help the student to keep the musical material under the control, as well as present models where the students can create their own approaches that will certainly be more efficient than having only traditional methods of learning to apply to new musical material. The process of learning is an ability that can always be improved, and it is best for the students to build on their own structures and models, when they can. Keywords: Analytical treatment, improvisation, mnemonic, harmonization, score reading.Bu makalede günümüzde piyano derslerinin "çözümleyici" olma ihtimali ele alınmakta; piyano eğitiminde kullanılan pedagojik yaklaşımların ağırlıklı olarak "geleneksel" yapıda olmasının eğitmenleri de öğrencileri de bazı yeni açılımlardan uzak tutabildiği düşünülerek, bu konu yeniden değerlendirilmektedir. Spontane deşifre, armonizasyon ve doğaçlama gibi belli beceriler geliştirilerek piyano egzersizleri ve eğitimine fonksiyonel bir boyut kazandıracak yollar ortaya koymak gerekliliği sorgulanmaktadır. Ayrıca bu çözümleyici mantık ve disiplin, yaratıcı düşünceyle deneyselliğin ortak zemininde ilişkilendirilmiştir. Şu andaki işler bakış açısını büyük oranda kabul edip sonradan çıkan yanlış algı veya hataları tamir etmek mümkündür. Keza tamamen sistemi reddetmek ve yeni baştan pedagojik öğretiler oluşturmak da diğer bir seçenektir. Bu iki uç yöntem arasında melezleme olarak görülebilecek üçüncü bir yöntem ise arayolu bulmaktır; sistemde daha önce yaygın şekilde kullanılmayan bazı öğelerin de işin içine katılması prensibi üzerinden yürüyen bu yaklaşım sorunları kolayca çözebilecektir. Geleneksel eğitime eskisinden çok daha kuvvetle taşınması savunulan kavramlar arasında armonik ve yapısal/ biçimsel analizin yanı sıra mnemotekni de bulunmaktadır. Mnemotekni ile bir liste verinin öğrenilmesi için yardımcı elemanların (görsel, işitsel veya dokunma duyusu ile ilgili) işin içine sokulduğu hafıza yöntemleri kastedilmektedir. Hatta bizi daha yüksek bir piyanistlik bilincine taşıyacak psikonörotik ve kinestezik yaklaşımlarla deşifre etmenin mümkün olabileceği ve daha yüksek verim alınabileceği ileri sürülebilir. Ancak bu yaklaşımlar, üzerinde çalışılması gereken ve potansiyel vadetmelerine karşın henüz net bir şekilde işlenmemiş projeler olarak görülmelidir. Çözümleyici yaklaşımla geliştirilmesi hedeflenen işlevsel beceriler ise notaya karşı kendiliğinden, yaratıcı ve esnek bir tavırla yaklaşabilme, bir melodinin armonisini anında doğaçlayabilme, kulaktan çalma ve transpoze etme yetilerinin kazanılmasıdır. Anahtar Kelimeler: Çözümleyici yaklaşım, doğaçlama, mnemotekni, armonizasyon, deşifre
II. Andronikos dönemi Konstantinopolis Manastırları?nda Philanthropia
Get PDFThe present study aims to focus on philanthropy during the reign of Emperor Andronikos II.The main sources of the study can be divided into two groups, namely primary and secondary sources. The first group consists of typikon (monastic charters) and historical accountsof the period such as Pachymeres Gregoras. It is possible to claim that Constantinopolitan monasteries of the era shared the same difficulties of the period in terms of philanthropy. They have limited income in order to survive and they are not volunteer to offer their limited sources to other institutions. Most of the typika of the period included special chapters as to not share or support any philanthropic institution. Athanasios, the Patriarch of Constantinople, deserves special interest for this research. Athanasios, as a originaly from monastic circle, tried to isolate monasteries from the outside world and blamed the extravert attitude of the monasteries for the failure of the empire. On the other hand, he struggled for the poor and obtained help from the emperor and rich. Besides, he was willing to share the monastic properties with the government in order to satisfy military needs, which paved the way for reaction from the monasteries. So, Athanasios and his management is the best proof for the dilemma of the Andronikos II?s period. Under the light of sources, there was thirty-eight active monasteries in the Andronikos II?s Constantinople. The present study focuses on the institutions which lied inside the city walls. Most of them was built or restored by the aristocratic families who were actively took part in politics and cultural life of the Palaiolgan period. Still others were built or re-built by the emperor himself and his immediate family. In addition to all there was some others which were constructed or restored by monks or patriarchs. The institutions which were restored by the aristocrats and the imperial family had great amount of income when one compares with the public in general but they were not willing to share their fortune with the public. They just limited alms and distribution of food only after the commemorations. They offered quite limited meal to the poor at the gate in certain dates.Besides, whole typika devoted an item in order to state that the monastery should be autonomous and self-governed. Self-governed monasteries also should have ephoros. Ephoros is a title that was given to a person who protect monastery and made possible that the monastery should govern as ktetor said. Most of the time this title is hereditary and given to the children of the ktetor. It is interesting that from the beginning monasteries and philanthropic institutions shared the same financial resources. In contrast, monasteries of the late Byzantine period became smaller than before and the philanthropic institutions that were inside or attached monasteries decreased in number and quality of the service they offer.So, monasteries started to keep their limited sources for themselves and excluded philanhropic institituions which means exclude the poor, children, orphans and the elder.On the other hand, monasteries of the Andronikos II?s era tried to find a way in order to help poor at the gate but they dismissed the needy children. For instance, in her typikon the ktetorissa (patron) of Bebaia Elpis Monastery forbid the education of children inside the monastery and refers limited alms and distribution at the gate. One can assume that despite the poor sources of Andronikos II?s monasteries they tried to act as philanthropic institutions.But their priority was to survive under this difficult circumstances. They just have few institutions and they ignore to attach to a philanthropic institution. When we compare this period with the Komnenian period, it is possible to claim that the monasteries of Andronikos II?s period became introvert and tried to avoid traditional roles of the monasticism during the long life of the Byzantine Empire. It is obvious that monasteries shared the economic instability of the period and they prefered to use their financial resources in order to survive. Therefore, one may assume that monasteries became more introvert and went away their traditional role as philanthropic institutions. Monasteries started to pay attention and became responsible towards the community who live inside the monastery and ktetors and their families. Keywords: Andronikos II, Palaiologan period, Constantinopolitan Monasteries, Philanthropy.II. Andronikos dönemi (1282-1328), Bizans İmparatorluğu tarihinde manastır hayatında altın çağın yaşandığı zaman aralığı olması açısından önem taşımaktadır. Ancak bunun yanında philanthropia olarak adlandırılan insan sevgisinin ve manastırların bu konudaki rolünün azaldığının görülmesi açısından dikkat çekicidir. Araştırmanın birincil kaynağını manastır yaptıranların (ktetor) hazırladıkları typikonlar (manastırın yazılı kuralları) oluşturmaktadır. Sözkonusu kaynaklar ktetorun manastırın uymasını istediği yönetimsel ve liturjik kuralları belirlemektedir. Bu kurallar, aynı zamanda manastırın dış dünyayla olan ilişkilerini ve bu ilişkilerin önemli bir parçası olan philanthropia hizmetlerinin sınırlarını da ortaya koymaktadır. Typikonlar dışında çalışmada II. Andronikos döneminin önemli tarihi kaynakları olan Pakhymeres ve Gregoras’ın tarihleri, manastırın adının geçtiği birincil kaynaklardan yararlanılmıştır. II. Andronikos döneminde Konstantinopolis kentinde suriçinde kalan ve faal olan manastırların sayısı 38 olarak belirlenmiştir. Bu yapı topluluklarının bir kısmı II. Andronikos döneminde inşa edilmiş, bir bölümü ise bu dönemde yapı eklemeleri ya da ciddi onarımlardan sonra kullanılmıştır. Bu dönemde manastırların Palaiologos döneminin ekonomik ve politik zorluklarını paylaştıkları ve geleneksel rollerinden sıyrılarak içe kapalı ve sınırlı kaynaklarını kendi varlığını sürdürmek için kullanan kurumlara dönüştükleri görülür. Dönemin Konstantinopolis patriği Athanasios’un bir yandan philanthropiayı desteklerken diğer yandan da imparatorluğun içine düştüğü felaketin sorumlusu olarak, dış dünyayla ilgilenerek asıl görevlerini unutan manastırları suçlaması ilgi çekicidir. Anahtar Kelimeler: II. Andronikos, Palaiologos dönemi, Konstantinopolis Manastırları, Philanthropia
Synthesis of well-defined polystyrene macrophotoinitiators by ATRP
Get PDFBu çalışmada, yeni tek ve çift fonksiyonlu atom-transfer radikal polimerizasyon (ATRP) başlatıcıları, 2-brompropanoil bromür’ün, 2-hidroksi-2-metil-1-fenil propan-1-on (HMPP) ve [4-(2-hidroksietoksi) fenil]-2-metil propan-1-on) (HE-HMPP), fotobaşlatıcıları ile kondenzasyonu sonucu elde edildi ve karakterizasyonu yapıldı. ATRP başlatıcıları ve bakır(I) kompleksi, Cu(I)Br/bipiridin, varlığında çözücüsüz ortamda, 110 0C’de gerçekleştirilen stirenin (St) atom transfer radikal rolimerizasyonundan, fotoaktif alkoksi fenil keton gruplarını içeren tasarlanmış polistiren makrofotobaşlatıcıları elde edildi. Başlama etkinliğinin kantitatif olduğu ve zincir ucunda veya ortasında istenilen fotobaşlatıcı fonksiyonu içeren dar molekül ağırlığı dağılımına sahip polistiren polimerlerinin sentezlendiği, Jel Geçirgenlik Kromatografisi, spektroskopik ve fotodegradasyon çalışmaları ile ispatlandı. Anahtar Kelimeler: Atom-transfer radikal polimerizasyon (ATRP), makrofotobaşlatıcı, polistiren.Macrophotointiators are polymers with a photoinitiator functionality at side chains or in the end or middle of the chain. These materials are of great scientific and technological interest because of their application in UV-curable coatings and as precursors for graft and block copolymers depending on the position of the photoinitiator moiety incorporated. Many macrophotoinitiators have been synthesized and their utilization in both applications have been studied. The major concern for their uses particularly in the latter application was related to the efficiency of functionalization, well-defined and predetermined structures, and low polydispersities. Obviously, if the all chains are not functionalized, upon irradiation non-funtionalized chains will not be activated and consequently remain as homopolymers in the system. In this study, new mono and bifunctional atom transfer radical polymerization (ATRP) initiators were synthesized by the condensation of 2-bromopropanoyl bromide with 2-hydroxy-2-methyl-1-phenyl propan-1-one (HMPP) and 2-hydroxy-1-[4- (2-hydroxyethoxy) phenyl]-2-methyl propan-1-one (HE-HMPP), respectively and characterized. The ATRP of styrene (St) in bulk at 110oC by means of these initiators in conjunction with a cuprous complex Cu(I)Br/bipyridine yields polystyrenes with photoactive alkoxy phenylketone groups.GPC, spectroscopic and photodegradation studies revealed that the initiation efficiency was quantitative and low-polydispersity polystyrenes with photoinitiator functionality in the end or middle of the chain were obtained. Keywords: Atom transfer radical polymerization (ATRP), macrophotoinitiator, polystyrene
Synthesis of imprinted gels which sensitive to specific target molecules and the effect of the physical parameters on the sensitivity
Get PDFMoleküler algılama; farklı türden molekülün bulunduğu bir ortamda, sadece belli bir molekülün, çoğunlukla zayıf fiziksel etkileşmeler aracılığıyla algılayıcı sisteme dönüşümlü olarak bağlanması ve salıverilmesi olarak tanımlanır. Biyolojik sistemlerde gözlemlenen moleküller arası özgün etkileşmelerin taklit edilerek endüstriyel amaçlı çalışmalara uygulanması son 20 yılın hızlı gelişen, disiplinler arası çalışma sahası haline gelmiştir. Yapay polimerler ya da polimerik jeller çok farklı özelliklere sahip monomerlerle sentezlenebilmektedir ve bunların özel bir teknikle (kalıplama tekniği) sentezlenmesi durumunda, biyolojik sistemlerde olduğu gibi, doğal seçici sistemlere benzer davranış gösteren yapay sistemlerin geliştirilebileceği düşünülebilir. Bu çalışmada hedef molekül olarak belirlenen floresans özelliğe sahip piranin molekülüne duyarlı jel sentezlenmesi ve bu jelin moleküler algılama kabiliyetinin jelin kompozisyonuna ve sıcaklık, pH, iyon derişimi gibi çevresel faktörlere bağlılığının araştırılması hedeflenmiştir. Karakterizasyon yöntemi olarak floresans spektroskopisi tekniği kullanılmıştır. Bu yöntemin en önemli üstünlükleri etkileşmeler hakkında oldukça zengin bilgi vermesi, uygulama kolaylığı ve maliyetinin düşük olmasıdır. Bu yöntem ile elde edilen spektrumlar değerlendirilerek jellerin Hafıza kabiliyetleri belirlenmiştir. Bu işlem bu tez kapsamında önerdiğimiz “Hafıza Parametresi” modeli ile gerçekleştirilmiştir. Hedef molekülün jele difüzyonu sonrası, jellerden alınan spektrumlarda meydana gelen dalgaboyu kaymaları yoluyla jellerin algılama kabiliyetleri tanımlanmıştır. Bu yolla tanımlanan ve ölçülen hafıza parametresinin kalıplanmamış jellerde sıfıra yakın çıkarken kalıplanmış jellerde en az 0.6 olarak bulunmuştur. Tezde sıcaklık, hedef molekül ve tuz derişimi, pH gibi parametrelerin algılama sürecine olan etkileri de ayrıntılı olarak tartışılmaktadır. Anahtar Kelimeler: Moleküler algılama, moleküler kalıplama, floresans spektroskopisi, polimerik jeller.The molecular recognition is defined as reversible adsorption -by means of weak physical interactions- of a specific molecule from a medium in which different kinds of molecules are exist together. Imitating the specific interactions available in the biological systems, and applying them to industrial applications have been one of rapidly developing interdisciplinary fields of last 20 years. Synthetic polymers or polymeric gels can be synthesized with monomers which have different functional peripheral groups. The physical interactions, like electrostatic, van der Waals, hydrogen bonding, and hydrophilic or hydrophobic, having different nature are possible between the polymer chains themselves, and also between the polymer chains and the solvent molecules. One of the most important properties of polymeric gels is undergoing phase transitions between collapsed and swollen states as a result of external stimuli. Namely, they are the smart materials which respond to external stimuli. This phase transition can be induced by temperature, solvent composition, pH, ionization degree of network, electric field or light. By synthesizing the polymeric gels with a special technique called as imprinting technique, it is possible to construct artificial systems showing similar behaviors with natural selective systems as in the biological systems. In these systems there are three different interactions between the target molecule and the host molecule. These are the covalent, non-covalent and semi-covalent (hybrid) interactions. The targets can be ions and molecules such as metals, small organic molecules like aminoacids, peptide, sugar and large organic molecules like polypeptide, proteins. In this work it is aimed to synthesis imprinted gels which can recognize the target molecule, pyranine, which is a fluoroprobe, and to study the strength of the recognition as a function of the composition of the gels and the environmental factors such as the concentration of the target molecule, temperature, pH and the concentration of the replacement molecules (NaCl). In these studies fluorescence technique was used as the experimental technique for characterization. Also absorption measurements were done to verify some of the fluorescence measurements. No stable dependence of the recognition on the concentration of the target molecules was observed. This is due to both the absence of replacement molecules and the loose network structure of the gel because of the small amount of crosslinker molecules. Since the network structure is very loose, the gel can not keep its initial conformation when it is collapsed. This means that the volume of the collapsed gel is smaller than the initial volume and also the size of the cavities in the gel is smaller. So this change in the sizes of the cavities destroys the imprinting effect. It was observed that at 60oC, although the gels were in collapsed state, the diffused amount of target molecules was the highest. And also the diffusion into the imprinted gel was much bigger than that of the random gel. At this temperature the imprinted gel has the most convenient conformation for the target molecules. But the random gel is not. Its volume is smaller than that of its initial volume. This smaller volume obstructs the diffusion into the random gel. It was observed that the diffusion into the gels at pH=4 is bigger than the other pH values. Since the pH of the conditions of synthesize of the gels were also around 4, it can be concluded that the microstructures of the gels became the most appropriate conformation at this pH value. Presence of the replacement molecules affects the diffusion of target molecules. At moderate concentrations of replacement molecules they bring the target molecules close to each other via the bridges constructed by the electrostatic interactions between Na+ and . In this case the fluorescence maximum of the target molecules is observed at both 430nm and 506nm. At high concentrations they separate the clusters and the fluorescence spectrum shift to 515 nm completely. The absorption experiments showed that the number of functionality groups of the target molecules was 3.1±0.9 for imprinted gel and 0.9±0.1 for the random gel. These values are very close the values given in literature. The ?Recognition Parameter? was defined first time in terms of the shifts in the wavelength of the fluorescence spectra of the gel in which the target molecules were diffused. It was calculated that it was almost zero for non-imprinted gels while it becomes bigger than 0.6 for imprinted gels. Keywords: Molecular recognition, molecular imprinting, fluorescence spectroscopy, polymeric gels.
Molecular binding characterization of genetically engineered solid binding peptides
Get PDFAnorganik yüzeyler çeşitli kimyasal gruplar kullanılarak fonksiyonel hale getirilmektedirler. Bu moleküllerin yüzeylerde oluşturdukları kendiliğinden örgütlenen yapılar ile yüzeylere istenilen fonksiyonellik kazandırılmaktadır. Ancak, kullanılan kimyasal moleküler bağlayıcılar tek bir yüzeye özgül olmamakta,birden fazla yüzeye afinite göstermektedirler. Çoklu malzeme içeren yüzeylerde kimyasal bağlayıcılarla aşılamayan bu durum, son yıllarda kombinatoryel biyoloji yöntemleri ile yeni nesil peptid moleküler bağlayıcılar kullanilarak aşılmaya çalışılmaktadır. Yönlendirilmiş evrim yolu ile faj gösterim ve hücre yüzey gösterim teknikleri kullanılarak farklı malzeme yüzeylerine özgül olan peptitlerin moleküler bağlayıcılar olarak kullanımı biyo-nanoteknolojik çalismalarda artan oranda ilgi toplanmaktadir. Bu çalışma kapsamında altın, platin ve silika yüzeylerine özgül olarak seçilmiş peptidlerin, adsorpsiyon kinetik parametreleri, peptidlerin yapısal özellilklerine bağlı olarak incelenmistir. Bu çalışma dahilinde peptidlerin anorganik yüzeylerle etkileşimleri yüzey plazmon spektrometresi ile incelenmiştir. Deneylerde, peptidlerin ilk seçilmis dizileri ile çoklu tekrarlarından oluşmuş diziler kullanılmıştır. Çalışma sonucunda platine özgül PtBP2, silikaya özgül bağlanan QBP1 ve altına özgül bağlanan GBP, moleküllerinde bu peptidlerin orijinal aminaasit dizilerinin üçlü tekrarlarının yüzeylerde kaplama yüzdesini artırdığı görülmüştür. Ancak platine özgül PtBP1 ve silikaya özgül QBP2 peptidlerinde aynı durum gözlenememiştir. Bu çalışma sonuçunda anorganik yüzeylere özgül peptidlerin göstermiş oldukları yüksek yüzey kaplama oranları sayesinde, katı yüzeylerin işlevselleştirilmesi için iyi birer moleküler bağlayıcı oldukları saptanmıştır.Anahtar Kelimeler: Peptidler, yüzey işlevselliği, moleküler tanıma, biyo-nanoteknoloji.Molecular recognition abilities of peptides and proteins have been exploited to create new generation of biomimetic molecular linkers. Peptide based molecular linkers were selected using combinatorial biology techniques, namely cell surface and phage display methods. Genetically engineered peptides for inorganics (GEPI) were screened and selected from phage display or cell surface display libraries. GEPIs were first characterized using qualitative techniques. However, this test was used as a preliminary step for the classification of the GEPIs. In this study we focused on the surface coverage of GEPIs. In the molecular characterization of GEPIs, adsorption kinetics and thermodynamics of GEPIs were realized in conjugation with secondary structural analysis of GEPIs. To characterize binding kinetics and thermodynamics of GEPIs, we employed surface plasmon resonance sensor. The sensing capability of SPR was only limited for adsorption on gold surface. We employed a reflectivity model, improved in Sarikaya group, to extend the sensing capability of SPR for the materials other than gold, namely platinum and silica surfaces. The reflectivity model guided us to prepare the right architecture for platinum and silica coated SPR chip surfaces. The surface coverage for gold binding peptide (l-GBP), platinum binding peptides (l-PtBP1and l-PtBP2) and silica binding peptides (l-QBP1 and l-QBP2) were determined. We carried out the surface coverage experiments for the one repeat of the peptides as they were selected from the libraries. GBP, gold binding peptide was selected from a cell surface display library. It is a 14 mer peptide and in previous studies it was demonstrated to have a high affinity to gold. Here we employed a surface coverage analysis for both l-GBP and its concatamer form 3l-GBP. For surface coverage analysis of GBP we found that there is a difference between l-GBP and 3l-GBP. The increase in surface coverage was not as prominent as the increase in binding affinity. We observed that the surface coverage of peptides were greatly influenced by the concentration of the peptide. Interestingly the difference in surface coverage of GEPIs was noticed at low concentrations of the peptides. In silica binding peptides groups, we tested two distinct silica binding peptides. QBP1 and QBP2. Both of the peptides were designed using bioinformatics tools, based on the knowledge generated from a combinatorially selected phage display library members. For QBP1 we noticed that, there is a difference in the surface coverage of the concatamer form, 3l, of the peptide. Interestingly we did not see any difference in the surface coverage of the one repeat and three repeat forms of QBP2. They seem similar to each other. The increase in the surface coverage upon displaying the concatamer forms of the peptides is regardless that the peptides are strong binder or not. We observed a comparable behaviour in the Pt binding peptides with the silica binding peptides in case of the repeating concatamers on surface coverage of the peptides. Here we investigated two platinum binders PtBP1 and PtBP2. They were both selected from phage display library as 7mer cyclic peptides. In PtBP1 peptide we did not observe any difference between the surface coverage values of l-PtBP1 and 3l-PtBP1. However, we noticed a difference between the surface coverages of l-PtBP2 and 3l-PtBP2. Despite of the fact that they were the strong binding peptides, they behaved differently in their surface coverage analysis. Here we demonstrated the surface coverages of PtBPs, QBPs and GBPs as a function of concentration. All of these peptides were the strongest binders for their corresponding surfaces. However, we explored a difference for their adsorption properties. Here we showed that the surface coverage of the peptides is not increasing as the number of GEPIs is increasing. The increase in the surface coverage of a GEPI is depended to the primary structure information of GEPI. Since the primary structure determines the secondary structure, we can conclude that , if the increase in the number of the repeats of GEPI favor for the conformational stability on the surface, then the surface coverage of the given GEPI increases. Surface coverage of a GEPI can be tuned by changing the conformational constraints affecting its structural stability on the surface. These properties make inorganic binding peptides ideal self assembling molecular tools for bionanotechnological applications. Keywords: Inorganic binding peptides, surface plasmon resonance, bio-nanotechnology, surface coverage
Urban image: findings from Istanbul
Get PDFYapısal çevresinin algılanması insan ve çevre ilişkilerinin incelenmesinde önemli bir araç olarak kabul edilmektedir. Çevresel algı kentsel çevrenin anlaşılması ve değerlendirilmesinde önemli bir rol oynar, yol ve yön bulmaya yardımcı olur, yönelme sağlar, deneyim kazandırır ve çevresel kalitenin artırılmasına katkıda bulunur. Kişilerin çevrelerini ne şekilde algıladıklarıyla ilgili araştırma sonuçları kentsel tasarım politikalarının geliştirilmesinde kullanılmaktadır. Bu çalışma, İstanbul için algısal imge ile ilgili bilgi toplama ve sonuçların tasarım sürecinde kullanılmasını sağlamak amacıyla gerçekleştirilmiştir. Çalışmada deneyimli anketçilerle rasgele olarak gerçekleştirilen 280 anket değerlendirilmiştir. Görüşülenlerden aynı zamanda toplanma alanları, sıra dışı yapılar ve yöreler, önemli akslar ve sınırları işaretleyebilecekleri bir harita çizmeleri de istenmiştir. Araştırmanın sonuçları tasarım kararlarının geliştirilmesinde kullanılmak amacıyla değerlendirilmektedir.A field study of the environmental perception is acknowledged as a valuable tool for registering the human interaction with the built environment and surrounding open spaces. Perceived images of the city plays an important role in the understanding of urban environment, helps to way-finding and orientation, gives people experiences and increases environmental quality. On theoretical grounds, this concentration of inquiry would be positioned under 'image studies'. In the study a perceptual analysis of Istanbul has been carried out in order to obtain deeper contextual information about the environment and to use this information to enhance the issuing of design strategies. The data was collected by a survey and trained interviewers administered a total of 280 questionnaires, to randomly selected respondents. The study was limited to the people who lived in planned areas, who were at least high school graduates, and had lived in Istanbul for more than five years. Two major representative groups were chosen, people, who lived in the central districts and people, who lived in peripheral districts. Two strategies were employed for gathering information: People were invited to verbalize their perception by answering the questionnaires and people were asked to make drawings according to the mental images they carried about the environment. They were asked to draw a map indicating the location of most important places, buildings, districts, roads and boundaries. The results of this research were shown similarity of general results of image studies that were nodes and paths, were generally perceived in high intensity level. In the research work, it was also found that the perceived image elements were located in city center, the level of perceptional intensity decreased outside of the city center
Comparison of valuation methods that can be used measurement of the economic values of urban green areas
Get PDFKentsel yeşil alanlar mekansal yapılarına ve işlevsel özelliklerine bağlı olarak kent mekanında fiziksel ve sosyal çevre bakımından faydalar üreten fonksiyon alanlarıdır. Kamu mekanı olma niteliklerinden dolayı sağladıkları faydalar, kamu yararı adına meşrulaştırılan ve uzun dönemde içselleştirilen faydalardır. Bu nedenle, faydalarının ekonomik değerlerinin doğrudan ölçülmesi mümkün değildir. Ancak kamu mekanlarının ürettikleri faydaların ekonomik değerlerini ölçecek yöntemler bulunmaktadır. Bu makalede, ölçüm yöntemlerinden koşullu değerleme yöntemi, seyahat maliyet yöntemi ve hedonik fiyat yöntemi ortaya konmuş ve kentsel yeşil alanların ekonomik değerlerinin ölçümünde kullanılabilecek en uygun yöntem, kavramsal olarak belirlenmeye çalışılmıştır.Urban green areas have an importance in urban areas because of their producing on-site and off-site benefits that are called external benefits. However, since they are accepted as public areas, their producing external benefits are for public and have long term effects. This is why, these known external benefits? economic values cannot be measured directly. It is accepted that the level of urban environmental quality is strictly related those external benefits. Those external benefits can be reflected mainly by urban green area standarts per person. If it is examined, urban green areas indices of urban areas in Turkey, it can be seen that they are not sufficient enough both in qualitative and quantitative properties. It is accepted that the main reason for that problematic situation is their immeasurable economic values directly. They are seen as if just with their cost for public, but are not producing of any economic values. However, there are some methods that are mainly based on environmental economics in order to measure economic values of public areas. In this article, three of these methods are mentioned conceptually. These mentioned ones are respectively, contingent valuation method, travel cost method and hedonic pricing method. After determining the conceptual framework of these three different methods, it is tried to argue the most appropriate one that can be used the measurement of economic values of urban green area
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