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Validation of the use of high dynamic range images and displays in lighting research
Get PDFBu çalışmanın amacı, Yüksek Dinamik Ölçekli (YDÖ) görüntüleme tekniğinin kullanıldığı YDÖ monitörlerin aydınlatma mühendisliği problemlerinin çözümünde kullanılabileceğini göstermektedir. Bu makalede sunulan ilk deney, YDÖ monitörde görüntülenen YDÖ fotoğrafların, LCD ekranda görüntülenen (tek pozlamadan oluşan) geleneksel fotoğraflardan daha gerçekçi olduğu hipoteziyle tasarlanmıştır. Altı adet hacmin detaylı parıltı ölçümleri noktasal ölçüm yapabilen bir parıltı ölçer ve parıltı kamerası kullanılarak yapıldıktan sonra, bu parıltı değerleri YDÖ ekrana yansıtılmıştır. Deney sonuçları YDÖ fotoğraf tekniği ile üretilen fotoğrafların YDÖ ekrandaki göruntülerinin, LCD ekranda görüntülenen tek pozlamadan oluşan fotoğraflardan daha gerçekçi algılandığını göstermiştir. Çalışmanın ikinci bölümünde, YDÖ görüntüleme tekniğinden faydalanılarak bir açık plan ofisteki aydınlatma kalitesi incelenmiştir. Bu çalışmada, görüntü karakteristikleri (ortalama parıltı, parıltı dağılımı ve doğal ışığı hacme alan pencere büyüklüğü) ile hacmin aydınlatma kalitesi arasındaki bağıntı incelenmiştir. Çalışmanın sonuçları, YDÖ ekranda sergilenen YDÖ fotoğrafların özellikle doğal ışık içeren görüntülerde aydınlatma kalitesi analizi yapmak amacıyla gerçek hacim yerine kullanılabileceğini göstermektedir. Henüz inşa edilmemiş binaların grafik simulasyonlarının, gerçek hacimde sağlanması öngörülen parıltı değerleriyle YDÖ ekranda görüntülenmesi, aydınlatma projesine ilişkin karar aşamasında faydalı olacaktır. YDÖ teknolojisi kullanılarak elde edilen sonuçlar literatürdeki çalışmalarla tutarlı olması, YDÖ teknolojisinin aydınlatma mühendisliği problemlerinin çözümünde kullanılmasına ilişkin güveni arttırmaktadır. Anahtar Kelimeler: Aydınlatma tasarımı, Yüksek Dinamik Ölçekli fotoğraflama tekniği, Yüksek Dinamik Ölçekli monitör, aydınlatma kalitesi, ofis aydınlatması.The main goal of this study is to show that a High Dynamic Range (HDR) display can be used in the study of lighting engineering problems, and as a tool in the lighting design process to enhance communications between lighting designers and their clients. Printed photographs, renderings or images displayed on conventional Cathode-Ray Tube (CRT) or Liquid-Crystal Display (LCD) monitors do not represent the spaces in realistic luminances. Calibrated HDR images contain luminance information from the real space, but current LCD monitors cannot present luminances as high as the luminances encountered in the real world. Therefore, these sources do not provide enough information to make accurate judgements of light and shade in the lighting design process. The HDR display used in this study could display luminances up to 4000 cd/m2 and overcame these problems. This research shows that the HDR method may be used as a surrogate for experiencing a real space to investigate lighting engineering problems both for research and the design process. The first experiment was designed to investigate the hypothesis that HDR images on an HDR screen would be perceived as more realistic than conventional images displayed on conventional LCD displays. Extensive luminance measurements were conducted using a spot luminance meter and a luminance camera to facilitate accurate reproduction of real space luminances of six scenes (corridor, gym, mezzanine, lobby, open-plan office, staircase) on the HDR display. Thirty-nine participants viewed six scenes in three modes: the real scenes (observing real spaces in the building), single exposure photographs of the scenes shown in conventional mode (screen resolution and luminance of HDR display adjusted to that of a conventional LCD display), and the HDR photographs shown in HDR mode (capable of luminances as high as 4000 cd/m2 and 216 distinct luminance levels). Half of the participants visited the real spaces first, and the other half saw the digital images first. For each presentation (real and digital images), participants rated what they saw on four semantic differential scales: dim - bright; non-uniform - uniform; unpleasant - pleasant; glaring - not glaring. Participants then viewed the six digital image pairs again, and recorded whether the HDR or conventional image was more realistic. This experiment demonstrated that HDR images presented on an HDR display are rated as significantly more realistic than conventional computer images. The second experiment demonstrated the use of HDR images as a research tool. The experiment focused on the relationship between scene characteristics (average luminance, luminance variability and view size) and space appearance judgements. Twenty-one scenes were created, each scene being the view from an interior cubicle across one cubicle to the exterior wall. The scenes varied in terms of the cubicle panels, window blind setting, and presence or absence of a neighbour in the adjacent cubicle. Extensive luminance measurements were conducted. Sets of bracketed images were taken for each of the 21 scenes, and then these images were combined into HDR images using the software Photosphere. The calibrated HDR images were shown on an HDR display at realistic luminances to 43 participants. The participants rated each scene on 8 scales. The average ratings for each image were plotted against the average luminance, luminance variability and relative view size for that image. The second experiment of the dissertation supported the hypothesis that as panel height in an open office gets lower, ratings for satisfaction with lighting increase, and ratings for privacy decrease. As the view size increased, ratings for satisfaction with lighting and amount of view increased. Regarding satisfaction with privacy, Hybrid (one fabric and one glass stack-on on the second panel) performed as well as Standing Privacy (two fabric stack-ons on the second panel), and regarding satisfaction with view and satisfaction with lighting, Hybrid performed better than Standing Privacy.The results imply that HDR displays may be successfully deployed in the lighting research projects. Both experiments show that people can respond to HDR images in the same way as they would respond to the real space. The results of both experiments are consistent with what is already known from studies of images and in real spaces, which adds confidence to the use of HDR display. Keywords: Lighting design, High Dynamic Range images, High Dynamic Range display, real space luminance matching, open-plan office lighting, lighting quality.
Usage of a special shotcrete panel to strengthen reinforced concrete frames
Get PDFDuvarların püskürtme beton ile güçlendirilmesi yöntemi, ülkemizde hasarlı veya hasarsız yığma binaların güçlendirilmesi amacıyla yaygın olarak kullanılmaktadır. Bu yazıda, püskürtme beton kullanarak; ülkemizdeki betonarme yapılara yönelik uygun, etkili, kolay uygulanabilir ve ekonomik bir güçlendirme yöntemi önermek amacı ile yapılmış olan çalışmanın bir kısmı sunulacaktır. Püskürtme beton ile güçlendirme yönteminin betonarme çerçevenin yatay yük taşıma, enerji yutma kapasitesi ve rijitlik özelliklerine olan etkisi ile sistemin göçme şekli incelenmiştir. Ülkemizdeki betonarme yapıların genel özelliklerini yansıtan tek katlı ve tek açıklıklı ½ ölçekli düzlem çerçevelerin içerisine tuğla duvar yerine ıslak karışımlı püskürtme beton paneller eklenmiştir. Oluşturulan panel; dış çerçevenin kirişlerine kayma kamaları kullanılarak bağlanmış, duvar ve çerçevenin birlikte çalışması amaçlanmıştır. Panel, kolon iç yüzeyine 20 cm mesafeli olarak yerleştirilmiştir. Panel genişliğine karar verirken, çerçeve kirişinde yatay ve düşey yükler etkisinde göreli olarak daha az eğilme momenti meydana gelen bir bölgede kalınması hedeflenmiştir. Üretilen numuneler, sabit düşey yük ve tersinir tekrarlı yatay yük çevrimleri etkisinde denenmiştir. Yalın çerçeve ile püskürtme beton bölme duvarlı çerçeve davranışları karşılaştırıldığında, önerilen güçlendirme yöntemi ile sistemin yatay yük taşıma kapasitesinin yaklaşık 1.6 kat arttığı gözlenmiştir. Püskürtme beton ile oluşturulan duvarın sistem davranışına etkisi analitik olarak da incelenmiştir. Anahtar Kelimeler: Püskürtme beton, güçlendirme, betonarme çerçeve.The existence of many vulnerable reinforced concrete buildings in earthquake prone areas that were built before the current Turkish earthquake code, presents one of the most serious problems facing Turkey, especially in Istanbul today. During 1999 Kocaeli Earthquake, buildings had greater damage than expected at that magnitude of an earthquake in the city. Since then researchers have been trying to find cheap and easily applicable strengthening solutions for the reinforced concrete and masonry structures. Shotcrete is used in lieu of conventional concrete, in most instances, for reasons of cost or convenience. Properly applied shotcrete is a structurally sound and durable construction material which exhibits excellent bonding characteristics to existing concrete, rock, steel, and many other materials. It can have high strength, low absorption, good resistance to weathering and resistance to some forms of chemical attack. Shotcrete is used for repairing of bridges, buildings, marine structures; underground excavations in rock; slope and surface protection and for new structures such as building pools, tanks, walls, floors and domes. Shotcrete can be applied by two distinct application techniques; the dry-mix process and the wet-mix process. In this study wet-mix shotcrete is used. Retrofitting structures with shotcrete is commonly used for damaged and undamaged masonry structures in Turkey. The aim of this study is to adapt this retrofitting technique to find out whether it is fast, cheap and adequate method for reinforced concrete structures. To understand the effect of this retrofitting technique, experimental research has been carried out. Panels made from wet-mixed shotcrete in lieu of a traditional masonry are used to form an infill wall within a vulnerable reinforced concrete frame. The frames were chosen to represent weak column/strong beam type structures that were very common in Turkey especially for the buildings constructed before the current earthquake code. The experimental work is composed of strengthening of one undamaged and one bare frame. Nearly ½ scale one story, one bay specimens were tested under constant vertical loads acting on the columns and lateral reversed cycling loads. The panel is connected to the beam and the foundation through shear studs used at two edges of the infill wall to create strong bond between panel and reinforced concrete members of the frames. They are connected by lapping the infill reinforcement to the anchorage placed in frame members. The panel has 20 cm distance to the columns. The specimens had non-seismic details such as large spacing of hoops, no hoop in beam-column connection region and no use of 135° seismic hooks. One story, one bay reinforced concrete frames with a portion of slab on top and a foundation at the bottom have been constructed in the laboratory. The cross sectional dimensions of columns and beam of the frames are 20 cm by 25 cm and 20 cm by 32.5 cm, respectively. The height and the width of the frames are 152.5 cm and 220 cm, respectively. Main reinforcement of the frames was consisted of 16 mm steel bars (average yield stress, fy = 270 N/mm2) and the reinforcement of the panels 4.5 mm steel bars (average yield stress, fy = 320 N/mm2). The reinforcement ratio of the column and the panel are 1.6% and 0.2% respectively. A wire mesh (Q 106/106) consisting of 4.5 mm steel bars was placed in the middle of the frame. By lapping the infill reinforcement to the anchorages placed in the frame members, full contact of the panel was established. The anchorages used were 10 mm steel bars placed in the frame by epoxy resin. The length of the anchorage in the panel was 20 cm. By using wet-mixed sprayed concrete, a 5 cm-thick panel was formed. The axial load applied on each column is 132.5 kN. Lateral reversed cycling loading imposed as displacement was applied to the specimen by means of a 250 kN-capacity hydraulic MTS actuators, which were placed at the slab level. Up to 0.467 mm top displacement, the cycles were applied only once. Later target displacements were repeated three times up to 42 mm. In this study, the effect of the technique on load carrying capacity, energy dissipation, rigidity and the failure mode of the frame is investigated with experiments. The results of the experiments show that the lateral load carrying capacity of the infilled frames strengthened using this method are approximately one and a half times that of the bare one. Keywords: Shotcrete, strengthening, reinforced concrete frame
Analysis of the bullwhip effect in distribution systems by dynamic simulation
Get PDFKamçı etkisi, tedarik zincirlerine ilişkin en önemli performans göstergelerinden biri olarak görülmektedir. Literatürde kamçı etkisinin nedenleri, ölçümü ve sistem davranışına etkisinin incelendiği çok sayıda çalışma yer almaktadır. Ancak bu çalışmaların çoğu, talep tahminlerinin ya da ikmal yapılarının uygulandığı tedarik zincirlerinde gerçekleştirilmiş olup, sipariş için üretim sistemi, özetlenen sistemler kadar ilgi görmemektedir. Bu çalışmada, dinamik simülasyon ile sipariş için üretim ve ikmal yapılarına ilişkin kamçı etkisi uluslararası dağıtım sistemlerinde incelenmiştir. Sipariş için üretim sisteminde tersine kamçı etkisi gözlemlenmiş ve ilk giren siparişin ilk servis edildiği politika ile siparişlerin havuzlandığı politika mukayese edilmiştir. Deneyler sonucunda sevkiyat aşamasındaki belirsizliklerin sistemi domine ederek arz bazlı hale dönüştürdüğü ve bu belirsizlik durumunda siparişlerin havuzlandığı yapının daha iyi sonuçlar verdiği ortaya konmuştur. Sevkiyata ilişkin belirsizliklerin elimine edilmesi durumunda ise ilk gelen siparişin ilk servis edildiği yapı daha iyi sonuçlar vermektedir. Ayrıca talep tahminine dayalı stok için üretim yapan bir sistemde ikmal politikasının uygulanması durumunda ikmal kapsamına dahil olacak ürünlerin seçimi için bir algoritma geliştirilmiştir. Bu durumda sistemin kamçı etkisi davranışı göstereceği ortaya konmuş, ikmal ve sipariş için üretim yapılarını bütünleştiren yeni ve kompozit bir model önerilerek ikmal parametrelerinin kamçı ve elde bulundurulan stok miktarını doğrudan etkiyeceği sonucuna varılmıştır. Anahtar Kelimeler: Tedarik zinciri, kamçı etkisi, dinamik simülasyon.The bullwhip effect has taken a widespread interest of research in the recent decade. It is seen as a natural outcome of order-to-delivery systems (Forrester, 1961). Most of the studies in the literature are focused on demand forecasts and replenishment policies (Lee et al., 1997a, Lee et al., 2006, Disney et al., 1997), while make-to-order systems have not taken same interest. It is aimed to analyze the bullwhip effect in distribution systems of international supply chains in this study by using system dynamics simulation. Dynamic simulation has been considered as invaluable in analyzing supply chains as a very efficient tool (Towill et al., 2006). In system dynamics, the system consists of feedback loops, levels and rates, and non-linear relationships between the system elements. The fundamental rule in system dynamics says that the structure affects the behavior (Sterman, 2000). The main behavior types are exponential growth, goal seeking, and oscillation; while s-shaped growth, s-shaped with overshoot, and overshoot and collapse are the behaviors resulting from the relationships between the basic behaviors (Sterman, 2000). One of the milestones in supply chain history can be seen as the ?beer game?, a managerial simulator developed by M.I.T. which consists of four echelons of a beer supply chain. Regardless the education and qualification of the players, the beer game usually results with shortage and excess stock. Sterman (1989) comments this case as ?misperceptions of feedback?, while Senge (1990) comments his fifth discipline as the system perspective under the light of this game. The bullwhip effect mainly results from four reasons which are demand forecasting, order batching, rationing game and price fluctuations (Lee et al., 1997a). Forrester (1961), Sterman (1989), and Senge (1990) has handled the bullwhip phenomenon with system dynamics while Holt et al.(1960), Blinder (1982), and Blanchard (1983) has macro economical studies. Many approaches like vendor managed inventory, jointly managed inventory, collaborative planning, forecasting and replenishment, collaborative transport management etc., have been started to be used in the recent years in order to maximize the coordination throughout the supply chain and reduce the bullwhip (Lee et al., 2006). Fransoo and Waters (2000) offered the ratio of variance of demands in and out of an echelon in a supply chain as a bullwhip measurement. A similar tool is also used in this study, in which the bullwhip parameter has been chosen as the ratio of variance of production over variance of sales. Two case studies have been done about the analysis of the bullwhip effect by dynamic simulation. First, the distribution subsystem of a make-to-order system has been chosen and it is observed that the system has been transformed into a supply-driven form generating reverse bullwhip behavior. It is also concluded by the simulation results that, the main reason of this transformation is the uncertainties at the shipment stage. Two policies have been compared in this study and it is observed that order pooling outperforms first-come-first-served in the uncertainty. After elimination of uncertainty at the shipment stage, first-come-first-served policy generates better results than order pooling as well as the previous simulations. In the second study, replenishment policy has been simulated in a system which currently runs on make-to-stock form, based on demand forecasts. An iterative model selection algorithm has been given for the models to be included in the replenishment policy. Several performance criteria has been chosen such as stock*days, inventory variance, lost sales percentage and the bullwhip. Simulation results indicate that the replenishment structure produces bullwhip, and more inventory carriage. A composite model of make-to-order and replenishment policies has been given afterwards. It demonstrates superior results in all performance criteria, producing greater bullwhip though. This bullwhip amplification mainly depends on the production time distribution. Finally, potential future research areas are listed under the light of obtained results. Keywords: Supply chains, bullwhip effect, dynamic simulation
Mechanisms of segregated household wastewater treatment by Membrane Bioreactor
Get PDFBu çalışmada, ayrık evsel atıksuların membran biyoreaktörde (MBR) arıtılma mekanizmaları araştırılmıştır. Çalışma, siyah ve gri atıksuların beslendiği pilot ölçekli iki ayrı batık MBR kullanılarak gerçekleştirilmiştir. Biyolojik arıtmanın kirletici boyutu üstüne etkisinin incelenmesi ve membranların verimli süzme boyut aralığının belirlenmesi amacıyla, atıksu ve aktif çamur örnekleri üstünde, KOİ için boyut dağılım analizi gerçekleştirilmiştir. Aktif çamur örnekleri üstünde gerçekleştirilen kirletici boyut dağılım analizi sonuçları ile membran süzüntüsünün konsantrasyonu karşılaştırılarak membranın verimli süzme boyutu tahmin edilmiştir. Buna göre, bu çalışmada kullanılan membranlar mikrofiltrasyon sınıfında ve 400 nm gözenek açıklığına sahip olmasına karşın, MBR içinde membran yüzeyinde biyofilm oluşması ve ikinci bir bariyer görevi görmesi sebebiyle verimli süzme boyutunun yaklaşık 8 nm değerine düştüğü ve ultrafiltrasyon sınıfında yer aldığı belirlenmiştir. Dolayısıyla membranın sadece biyokütle ile su fazının ayrılmasını sağlamakla kalmadığı, büyük molekül ağırlığına sahip ayrıştırılamayan çözünmüş organik maddelerin de reaktör içinde tutulmasını sağladığı belirlenmiştir. Bu noktadan hareketle, çözünmüş kalıcı KOİ’nin MBR’larda akibetinin araştırılması için atıksu, MBR içinden alınan aktif çamur numunesi süzüntüsü ve membran süzüntüsü arasında kararlı denge için kütle dengesi eşitliği kurulmuştur. Kütle dengesi eşitlikleri sonucunda, konvansiyonel sistemde ayrıştırılamayan bir kısım çözünmüş kalıcı KOİ’nin MBR’larda ayrıştığı belirlenmiştir. Her iki MBR’da da çözünmüş kalıcı KOİ’nin ayrışma verimi, reaktör içinde tutulan fraksiyon değerlendirildiğinde %95, çözünmüş kalıcı KOİ’nin tamamı dikkate alındığında ise %50 civarında bulunmuştur. Anahtar Kelimeler: Membran biyoreaktör, gri su, siyah su, çözünmüş kalıcı organik madde.Worldwide, one in five persons does not have access to safe drinking water, whereas half of the world's population does not have access to sufficient sanitation (WHO, 2000). In addition, stress on water resources increases because of pollution, ineffective water use, increasing water demand and droughts. In the current conventional wastewater management, end of pipe, approach all types of wastewater are mixed, transported in a sewer system, and treated in a wastewater treatment plant. However, the sewer systems usually do not end up with an appropriate treatment plant. As a result, uncontrolled wastewater discharges cause serious problems in the receiving environment. Recently, "decentralised sanitation and re-use" (DESAR), which is a logical on-site source separation and reuse based approach, was proposed as an alternative to current "end of pipe" approach. On household level, two main sources of wastewater are recognized which are grey and black water. In this framework, treatment by MBR may be a promising alternative for small scale systems with the high hygienic standard effluent quality, reduced reactor volume, smaller footprint and operation easiness due to reduced net sludge production at high sludge ages. Two pilot-scales submerged MBRs were constructed for grey and black water treatment equipped with plate and frame type membrane modules. In the first part of this study, detailed characteristics of grey and black water in terms of aerobic biodegradability related kinetic and stoichiometric model parameters, which are missing in the literature, were determined based on batch experimental study and respirometric tests. Assessment of biodegradable COD fractions and kinetic and stoichiometric constants were done by model fitting of the OUR data (Insel etal., 2003). The OUR data was analyzed according to endogenous decay modified ASM1 (Orhon and Artan, 1994). For the case of black water as the large fraction likely to cover a wide range of compounds with different biodegradation pattern, dual hydrolysis rate is assigned. For the case of grey water, a single hydrolysis rate is sufficient to explain the hydrolysis. The results of aerobic biodegradability characterization showed that the kinetic and stoichiometric coefficients of grey and black water were in accordance with the previously reported values for domestic wastewater. Compared with black water, hydrolysis rate of grey water was found to be lower, which is attributed to the slowly biodegradable detergents, soaps and cleaning agents heavily found in grey water. The combined wastewater followed the kinetics of black water. Wastewater characterization usually includes, a single filtration size (450 nm), which conventionally differentiates soluble and particulate COD components. In this study, size information of pollutants has been explored in a much wider range between 2nm to 11 m for a better understanding of feed water characteristics. Furthermore, size distribution study was also performed on the reactor bulk liquids of the MBRs mainly for better understanding of membrane separation and the fate of soluble non-biodegradable organics in MBRs. It is found that due to biofilm formation, serving as an additional separation barrier on the surface of the membranes, the effective filtration size is in the range of ultrafiltration, around 5-14 nm, although the membrane itself is in the size range of microfiltration with the 400 nm pore size. In conventional activated sludge systems, HRT controls the retention time of soluble COD, which is the filtrate of 450 nm filter. On the other hand, in MBRs this statement is not true anymore. Membrane separation decides the residence time of pollutants depending on the effective filtration range of the membrane and size of pollutants. As a result of size distribution analysis of bulk liquid, it is found that the retained soluble residual organics, which are accepted as non-biodegradable in conventional activated sludge systems, are slowly biodegraded, around 50% and 95% for overall soluble residual organics and the retained fraction in the reactor bulk liquid respectively. Similar results were obtained for both of the MBRs. According to the findings of this study, it can be concluded that the difference between MBRs and conventional activated sludge systems is not just a physical separation by a membrane. Furthermore, better understanding of fate of soluble organics in MBRs will be a step for better understanding of membrane fouling mechanisms. Keywords: Membran Bioreactors, grey water, black water, DESAR, soluble residual organics
Nutrient recovery from anaerobically digested sewage sludge by struvite precipitation
Get PDFBu çalışmada, kentsel nitelikli anaerobik çürütülmüş çamurdan strüvit formunda nütrient geri kazanımı potansiyeli araştırılmıştır. Çürütülmüş çamurun katı fazından fosforun geri kazanımı için, katı faza fosfor çözündürme prosesinin uygulanması gerekmektedir. Çalışmada, çürütülmüş çamur katı fazına asidik koşullarda fosfor çözündürme prosesi uygulanması ile mevcut fosfor ortofosfata dönüştürülmüştür. Asidik koşullarda çözündürme prosesi ile oldukça yüksek nütrient içeriğine sahip (1085±4.95 mg/L NH3-N ve 840±21.21 mg/L PO4-P) fosforca zengin sıvı fazı elde edilmiştir. Asidik çözündürme prosesinin uygulanması ile katı fazdaki toplam fosforun yaklaşık %84’ü çözündürülmüştür. Fosfor çözündürme prosesinin strüvit çöktürmesi için başlangıç adımı olarak kullanılabileceği görülmüştür. Strüvit çöktürmesi testlerinde, Mg:N:P ve Mg:P molar oranlarının etkisi ayrı ayrı incelenmiştir. pH 8.5’da, Mg:N:P molar oranının 2:1:1.3 olduğu durumda PO4-P ve NH3-N giderim verimleri %99.84 ve 40.19 olarak elde edilmiştir. Bu durumda, strüvit çöktürmesi ile PO4-P’nin büyük bir kısmının NH4-N’nin ise belirli bir kısmının geri kazanımı gerçekleştirilmiştir. Asidik koşullarda çözündürme uygulaması sonucu fosforun yanı sıra serbest kalan metal iyonları, strüvit çöktürmesi sonucunda metal fosfatlar olarak çöktürülmüştür. Çalışmada, asidik çözündürme sonrası sıvı fazda mevcut bulunan Ca, Al, Fe ve Zn metallerinin yüksek konsantrasyonlarından dolayı, giderilen PO4-P’nin tamamı magnezyum amonyum fosfat olarak strüvit formunda giderilmemiştir. Bu durum strüvit katı fazında yapılan XRD analizi ile desteklenmiştir. XRD analizi sonucu, strüvite ek olarak diğer metal bileşiklerinin de mevcut olduğu görülmüştür. Anahtar Kelimeler: Fosfor çözündürülmesi, çürütülmüş çamur, nütrient geri kazanımı, strüvit çöktürmesi.The recovery of nutrients from the anaerobically digested waste stream is a potential source of revenue. There is an increasing awareness of limited natural resources and importance is given to the sustainable treatment activities; that is why control over the sources of N and P shifted from removal to recovery. This can be explained by the dependency of modern agriculture on P derived from phosphate rock. Phosphorus is an essential nutrient for all forms of life. Phosphorus consumption in the world in year 2006 was around 142 million tons of phosphate rock concentrate, which is annihilating economically extractable phosphate rocks. Therefore, the reliance on phosphate rocks should be stopped and sustainable ways to use phosphorus should be researched. A sustainable way to use phosphorus can be recovery of phosphorus from digested sewage sludge since almost all the removed phosphorus accumulates in treatment sludge in a conventional wastewater treatment plant whether phosphorus in wastewater is removed by biological phosphorus removal or by chemical phosphorus removal. Since mineral fertilizers account for approximately 80% of phosphates used worldwide, it would be beneficiary to recover phosphorus from digested sludge as a fertilizer. On the other hand, as a basic building block of plant protein; nitrogen is an essential element for agriculture and there is a growing demand for the nitrogenous fertilizer in the world. One of the most popular nutrient recovery applications in this sense is converting nutrients from digested sludge into magnesium ammonium phosphate hexahydrate (struvite). Struvite is a slow releasing fertilizer. Nutrient recovery from anaerobically digested sewage sludge is a viable option because digested sewage sludge is rich in nutrients. Moreover, most of the studies in literature focused on the removal/recovery of the readily available nutrients in the anaerobic digester effluents and little attempt were given on the extraction of the nutrients present in the solid phase of the anaerobic digester effluents. Therefore, this study focused on the removal and recovery of nutrients as struvite from solid phase effluents of a full-scale sewage sludge anaerobic digester. Nutrient recovery from the solid phase was achieved by the adoption of a novel phosphorus dissolution process. The recovery of nitrogen and phosphorus can only be done by using the dissolved fraction, but most of the nutrients are located in solid form. For this purpose, the solid phase was subjected to phosphorus dissolution process, thereby obtaining phosphorus-enriched liquid phase. The use of acidic phosphorus dissolution process was applicable to the solid phase of the full-scale sewage sludge anaerobic digester and can be used as a preliminary step of struvite precipitation experiments to obtain a nutrient rich solution. The dissolution of phosphorus from digested sludge consists of the following steps: Dissolution of the sludge using acids and separation of the phosphorus-enriched liquid phase from the remaining solid phase. The use of acidic phosphorus dissolution process led to the transformation of available phosphates into the orthophosphate. In this study the phosphorus-enriched liquid phase with considerably high concentrations of nutrients (1085±4.95 mg/L of NH3-N and 840±21.21 mg/L of PO4-P) was obtained. More than 80% phosphorus dissolution can be achieved at pH 2.0. In addition to the increase of orthophosphate concentration, acidic dissolution resulted in the release of the metals which were normally integrated in organic complex molecules into the liquid phase. Metals can be incorporated into the crystal lattice or sorbed to the surface of struvite. The phosphorus-enriched liquid phase was analyzed for the metals and heavy metals. In the struvite precipitation experiments conducted with the phosphorus-enriched liquid phase, the effects of molar concentration ratio of Mg:N:P and molar concentration ratio of Mg:P were investigated, separately. In the experiments conducted with the phosphorus-enriched liquid phase of digested sewage sludge by the addition of external phosphorus and magnesium, high recovery efficiencies (>99.7%) of PO4-P and partial recovery of (up to 40%) NH3-N was observed. Whereas in the experiments conducted by the addition of only magnesium, almost complete recovery (99.9%) of PO4-P and partial recovery of (only 5%) NH3-N was attained. The obtained results of the experiments indicated that struvite precipitation process can be used to recover PO4-P only or both NH3-N and PO4-P. The results from XRD analysis for the struvite precipitate collected from the reactor containing phosphorus-enriched solution indicated a struvite formation. Keywords: Phosphorus dissolution, digested sewage sludge, nutrient recovery, struvite precipitation
Livable space, land-use intensity in Istanbul
Get PDFNüfusu hızla artmakta olan metropollerde ve özellikle ekonomik olarak gelişmekte olan ülkelerde kentsel arsa talebi ile arzı arasındaki açığın ümitsiz olduğu gözlenmektedir. Kentsel konut üretimi için kamu tarafından sağlanması gereken sosyal ve teknik altyapı maliyetlerinin yüksekliği kentsel arazi arzını kısıtlamakta ve arazi değerini ve yoğunlukları etkilemektedir. Hızlı büyüyen bir nüfusa ve kısıtlı ekonomik kaynaklara sahip olan İstanbul metropoliten kentinin konut sorunu araştırılırken arazi üzerindeki yüksek yapılaşma baskısı ve bunun göstergesi olan arazi değerleri ve iskan yoğunlukları desenini oluşturacak verilerin derlenmesi önem taşımaktadır. Bu çalışmada, İstanbul’da belli konut tipolojileri ve konut yerleşim alanları için yaşanabilir alan (Livable Space) standartlarının oluşturulabilmesi amacıyla, yapılaşma yoğunluğu ile yaşanabilir alan arasındaki ilişki araştırılmaktadır. Araştırmanın metodolijisi, rastgele seçilmiş farklı konut yerleşim alanlarını içeren 150 sokakta, arazi değerleri ve yapılaşma yoğunlukları ile ilgili verilerin toplanması ve analiz edilmesi olarak belirlenmiştir. Seçilen 150 noktada yapılaşma yoğunluğu, Taban Alanı Katsayısı (TAKS), Kat Alanı Katsayısı (KAKS), ve konut tipine bağlı olarak Kullanılabilir Açık Alan Oranı, Yaşanabilir Alan Oranı hesaplanarak veriler optimum yaşanabilir alan standartları ile karşılaştırılmıştır. Sonuç olarak, İstanbul’da konut alanlarının büyük çoğunluğunda KAKS değerinin 1.00 ile 3.00 arasında, TAKS değerinin 0.25’in üstünde olduğu ve yoğun bir yapılaşma gösterdiği tespit edilmiştir. Bu koşullarla açık alan ve yaşanabilir alan oranları karşılaştırılmış ve konut alanlarının yüzde otuzu açık alan oranı açısından, yüzde kırkı da yaşanabilir alan oranı açısından standardın altında olduğu saptanmıştır. Anahtar Kelimeler: İstanbul, konut,arazi değeri, yoğunluk, yaşanabilir alan.Implications of the gap between the supply and demand of urban land in the Metropolitan areas of economically developing countries are reflected in the high costs of residential land and high land-use intensities. Social and technical infrastructure put a heavy burden on the municipalities with limited resources and restrict the supply of urban land and affect its value. This article examines the case of Istanbul Metropolitan city, with its limited economic resources and high population growth rates. The analysis is concerned about the 'sustainable development' of Istanbul and addresses the spatial concepts like compactness, density and quality of life. While it is widely accepted that there is no strong correlation between density and quality of life, 'density' is still a basic tool used in planning to achieve a certain type of settlement. The number of people, dwelling units, amount of open space, green space, recreation etc. will change according to density decisions. The study aims to document the land-use intensity values and the ratios of Open Space, and Livable Space and to analyze the differentiation of these ratios in different residential environments with different house types in Istanbul. The land-use intensity measures that are normally used in urban planning in Turkey are basically: the Floor Area Ratio and the Building Coverage Ratio. These two ratios help to control the maximum amount of construction on a site and the maximum amount of land to be covered by construction. They are related to land values and density decisions. But they do not help to control the amount of open space especially the open space used by pedestrians in residential areas. Also, measures like the amount of car parks and recreational areas that are related to the quality of the physical areas are not considered. The methodology used in the survey comprises the data collection and analysis of the parameters affecting land use intensity and ratios of open space, of parking areas, of recreation space and of livable space. Data has been collected in 150 randomly selected streets representing different residential areas of Istanbul. Land-use intensity parameters like the Floor Area Ratio, Building Coverage Ratio, Open Space Index, Recreation Area Ratio, Parking Area Ratio and Livable Space Index, were calculated for each of the 150 points within an area of 100 m. radius around them and the results were compared with land values and optimum standards given for different house types. The results show that the randomly selected points (residential buildings) on 150 streets represented all types of residential areas in Istanbul. The results related to the Floor Area Ratio that is used in urban planning to control land use intensity in Turkey show that in the large majority of residential areas the ratio is between 1.00 and 3.00. The results related to the Building Coverage Ratio show that in more than three thirds of the residential areas the ratios are over 0.25. These findings indicate that Istanbul is a compact city and that the buildings are constructed very densely. The results related to the Open Space Index show that more than one-third of residential areas have lower ratios (less open space compared to the total construction) than the expected minimum ratios. Results related to the Livable Space Index show that in more than forty percent of the residential areas the ratio is below minimum standards. It was observed that as the as the land use intensity ratios like the Floor Area and the Building Coverage Ratio increased the Open space Ratio and the Index of Livable Space decreased. The most critical situations were observed in residential areas where the Floor Area Ratios were over 1.50. Though no direct correlation was observed between the land values and the Livable Space Index, a complex relationship between the Floor Area ratio, the Livable Space Index and House Prices was observed. Highest prices were observed in areas with lower than 1.50 Floor Area ratios and related optimum Livable Space Indexes. This finding of the research that the inhabitants in Istanbul pay higher prices for higher standards clearly indicates that they are sensitive towards the standards of livable space. It was also important to see that residential areas with more than 1.50 Floor Area Ratios had problems in providing acceptable standards of Livable Space. In residential areas with higher land use intensities higher design skills and more careful organization of livable space is necessary. Otherwise as observed in the existing high density, unplanned areas in Istanbul, low quality of life will be widespread in the residential areas of Istanbul. Therefore, urban planners and Planning Agencies should develop a good understanding of the Livable Space Index and use it to overcome the degradation of the quality of life in the residential areas of Istanbul. Keywords: Istanbul, housing, land value, density, livable space
Investigation of education infrastructure and campuses trends of outside in Istanbul
No full text1970 sonrasında dünyada, 1980 sonrasında Türkiye’de hızlı bir değişim dönemine girilmiştir. Özellikle ekonomik, sosyal, teknik ve politik alanlarda yaşanan değişimler, yeni olguların ortaya çıkmasına yol açmıştır. Eğitim, yeni olguların ortaya çıktığı, hızlı değişimlerin yaşandığı alanların başında gelmektedir. Yaşanan değişimlerin bir sonucu olarak, Türkiye’de eğitim donatımı planlamasının ve uygulamasının yeniden ele alınmasına ve yeni yöntemlerin geliştirilmesine ihtiyaç duyulmaktadır. Bu çalışmada, İstanbul’da eğitim donatımlarının kent dışı kampuslaşma eğilimleri irdelenmektedir. 2001 yılında İstanbul’da 466 kamu okulu, 91 özel okul, 3 devlet üniversitesi ve 6 vakıf üniversitesi ile gerçekleştirilen anket çalışmasından elde edilen veriler, istatistiki analize tabi tutulmuştur. Değerlendirme sonucunda, geleneksel planlama yaklaşımının ortaya koyduğu eğitim donatımı planlamasının ve uygulamasının aksine, İstanbul’da eğitim kademelerinin tümünde, kent dışı kampuslaşma eğiliminin benimsendiği gözlenmiştir. Planlamada yaşanan bu boşluğun ortadan kaldırılması amacıyla “İstanbul’da Eğitim Donatımları Yer Seçim Model Şemaları” geliştirilmiştir.A period rapid change is observed after 1970 in the world and after 1980 in Turkey. Especially the changes experienced in the economic, social and political aspects caused new facts to appear. And education comes first on top of the fields where such new facts appeared and rapid changes occurred. As a result of these experienced changes, new methods and principles are required to be developed in Turkey for the re-planning of the traditional education infrastructure and the application of the new system. This Thesis deals with the trends towards establishment of education campuses outside of the city of Istanbul. The data obtained from an inquiry having been performed in Istanbul in 2001 at 466 public schools, 19 private schools, 3 state universities and 6 foundation universities have been statistically analyzed. The assessment results of this analysis showed that, on the contrary of the existing education infrastructure planning and establishment procedure as laid down by the traditional planning approach, the trend towards establishment of education infrastructure campuses outside of Istanbul is embraced at all levels of education in the cityIn order to remove this gap in planning process, "Models for the Planning and Application of Education Infrastructure in Istanbul" have been developed which refer to the economic, social, environmental and local development of Istanbul
The relationship between the upper level planning system and disaster management
Get PDFBu çalışmada, planlama sistemi ve afet yönetimi ilişkileri sistemci bir yaklaşımla incelenmiştir. Planlama sisteminin alt sistemlerinden birisi olan üst düzey planlama sisteminde, afet yönetimi kapsamında yaşanan sorunlar ve sistemin sağlıklı çalışmadığı noktalar neden-sonuç ilişkisi içinde değerlendirilmiştir. Afet yönetiminin afet öncesi çalışmaları kapsamındaki ana kaynağı, üst düzey planlar ile başlayan ve yerel ölçekteki planlarla uygulama bulan “Planlama Sistemi”nin doğru çalıştırılması ve yerleşmelerin yer seçiminin sağlıklı bir biçimde yapılmasıdır. Afet etkilerine duyarlı olarak hazırlanacak; kalkınma planları ile başlayan bölge planları ve çevre düzeni planları ile devam eden hiyerarşik yapının, yerel planlama sistemi ile bütünleştirilmesiyle, kentlerimiz, çok daha sağlıklı ve güvenilir mekanlardan oluşabilecektir. Bu aynı zamanda etkin ve verimli bir afet yönetiminin de en önemli adımı olacaktır.In this study, the relationship between the planning system and disaster management has been examined in a systemic approach. The upper level planning system, one of the sub-systems of the planning system, the problems faced in the scope of disaster management within it and its points of handicap have been evaluated in the frame of reason-result. A general approach is that; the longest and effectively the most strategic part of disaster management, which is defined as a process covering the activities that need to be carried out before, during and after a disaster, is the activities carried out before a disaster. The main source of these activities is the proper functioning of the "Planning System", which begins with upper level plans and is put to practice with local level plans and the healthy selection of location for areas of settlement, hence preventing any negative effects of the disaster at the source. It is very important that the planning system work efficiently in a hierarchical structure to reduce the effects of disasters. Our cities will be much healthier and safer places when plans that is sensitive to the effects of disasters are prepared; a hierarchical structure that begins with national development plans and continues with regional and superior physical plans and is made complete with the local planning system. This at the same time will be the most important step towards an affective and efficient disaster management
Değişimin işareti olarak III. Ahmed ve I. Mahmud devri Osmanlı sebilleri
No full textSebil is a public donation, for the distribution of cold drinking water, sweet drinks or fruit juice to passers-by in cups. Ottoman sebils has many different variations and form in time. Some are just huge water jar with a simple tap; some have a window with basin where water pours into; some are monumental buildings like a small kiosk with open and enclosed spaces. Sebil buildings, built in Ahmed III and Mahmud I period (1703-1754), are the buildings where change in 18th century Ottoman architectural style can be observed gradually. Examining these sebils shows that there were three different artistic approaches and architectural styles within the period. The first architectural period was between 1703 and 1718. The sebils built in this period, reflect the traditional Ottoman style as formed in the 16th and 17th century. These sebils are polygonal in plans, and has pointed arches above dispense windows. These sebils are generally "stuck" between row of buildings. The second period last from 1718 to 1740. This period is also called as "Tulip Age", and some changes were occurred in sebils for the very first time in this period. First example in this period was the sebil built by grand vizier Ibrahim Pasha in 1720. These sebils are generally on the most dramatic corners of the city; they have circular plans; the facades are full of ornamental relief and they are more decorative in all sense. Sebils of this period are also elevated vertically, adorned with vertical pilasters. They have wide eaves projecting over all façades of the buildings; and domes with high drums. In this content, their design has similarities with Persian "kiosk" architecture and especially India-Mongol pavilion architecture. However, the architectural elements and details remain traditional. After 1740, in the last period, some radical changes appear on sebil buildings. The first example of this brand new approach is Emin Aga Sebil. The main common points of these buildings are symmetry in façade, baroque curves in plan, and more architectonic ornamentation instead of arabesque motifs. These changes are not only in the general design but also in the architectural details and vocabulary. Arches were transformed to the undulating ones as seen in Italian Baroque architecture; capitals were decorated with acanthus leaves or volutes recalling the Corinthian and Ionic capitals. The reasons behind the changes in Ottoman architecture of these periods are various. First, after a long time of "classical" Ottoman architecture period, which lasted since 1450s, the artists and patrons might seek for "novelty". Initially, it seems that the source for novelty was in the East, especially Persia, India and even China. Later, Western influences were more dominant, especially architecture in Italian Peninsula and France of 17th and 18th century. Sebil buildings must have been seen as ideal buildings to put into practice the "search for novelty". As non-religious buildings, they were free from limitation and conservatism of religious architecture. They are small buildings, compared to mosques, palaces, schools etc, so it was easy to apply new techniques and details. In addition, they could be built by small group of artisans instead of gross work of official architecture bureaucracy of that time. Probably, architecture books, illustrated catalogs and similar publications affected the Ottoman architects to build new building in new styles. Nevertheless, the changes stayed limited in sebil buildings until the end of the period. These sebils in their extra ordinary appearance were built side by side with mosques and other buildings that were very traditional in style. This contradictory phenomenon ended with Nuruosmaniye Building Complex, built in 1754 by Ottoman Sultan Mahmud I. In this huge complex every building, including mosque, reflects the new perspective of the 18th century Ottoman architecture that begun with the construction of sebils. The Ottoman culture produced its ideal spaces within the continuity of its artistic and social tradition. We can consider the 18th century, as a period of architectural innovations within the internal dynamic and potential of the Ottoman architectural tradition. The thematic repertory was enriched with fresh motifs end used with combination of old forms. The. The new model was built upon the collage of elements inspired from the architecture of both the Eastern and the Western cultures. This innovative modeling brought a prosperous new way to Ottoman architecture. Keywords: Otoman, architecture,18th century, Ahmed III, Mahmud I, Tulip Age, baroque, sebil.Osmanlı sebilleri, cami içlerine konan ve su küpleri ya da teknelerinden oluşan basit sebillerden; birkaç kapalı birimden oluşan büyük ve anıtsal sebillere kadar pek çok tipe sahiptir. III. Ahmet ile I. Mahmut’un saltanat dönemine denk gelen 18. yüzyılın ilk 50 yılı, Osmanlı mimarlığı için eşi az görülür bir “değişim” ve “yenilik” dönemidir. Bu dönem mimarisi, muhteşem bir klasik devir yaşamış olan anıtsal Osmanlı mimarisine, artık tekrarlarla kalıplaşma tehlikesi belirdiği bir zamanda, canlı ve yeni bir yaratma devrinin kapısını açmıştır. Daha önemlisi Osmanlı insanı, ilk olarak bu çağda “yeni” olma, “daha önce yapılmamış” olma niteliklerini bir değer kalemi olarak kendi zihniyet yapısının içine katmış gözükmektedir. Bu devir sebilleri de, Osmanlı toplumsal yapısındaki değişimle paralel olarak mimarideki değişimin en iyi takip edilebildiği yapı türüdür. İncelenen sebilleri üç döneme ayırmak mümkündür. 1703–1718 arası ilk örnekler, 17. yüzyıl mimari anlayışının devamıdır. 1718–1740 arası Lale Devri ve onun etkisindeki dönemde ise sebillerde bazı yenilikler görülür. 1740’dan sonra, sebillerde artık klasik mimariden tam bir sapma görülür, yeni bir dil geliştirilir. Yeniliğin kaynağı ise çok çeşitlidir; 1718-1740 arasındaki dönemde Hint-İran etkisini akla getiren örnekler ağırlıktadır. 1740’dan sonra ise açık bir Avrupa etkisi ağır basar. Bu etkinin sebillerde görülmesinin nedeni; sebillerin, dinsel kalıplar dışında kalan yapılar olmasıdır. Yaptıranların durumları açısından da bu yapılar, baş mimarın emek ya da takibini gerektirmeyen yapılardır ve çözümü zor teknik sorunlar içeren yapılar grubundan değillerdir. Ancak yine de bu sebil düzenlemeleri, geleneksel mimarinin kalıplarından çıkmayan diğer tipteki binalarla bir arada inşa edilmiştir. İlk kez Nuruosmaniye Külliyesi’nde bu tutarsızlık ortadan kalkmış, sebille birlikte tüm külliye yapıları bu yeni anlayışı yansıtır biçimde inşa edilmiştir. Anahtar Kelimeler: Osmanlı, mimarlık, 18. yüzyıl, III. Ahmed, I. Mahmud, Lale Devri, barok, sebil
Risk analysis for urban cultural heritage and, Büyükada case
Get PDFTarihi kentsel çevreler için varolan sistemde koruma çalışmaları ve afet riski azaltımı, birbirinden bağımsız işleyen iki süreçtir. Bu makalede, tarihi kentsel çevrenin bütünü ve kentsel kültür mirası için doğal afet kaynaklı risklere yönelik bir analiz yöntemi önerilmektedir. Bu risk analiz yöntemi, Adalar-Büyükada yerleşimi genelinde deprem, yangın ve sel afetleri için denenmiştir. Önerilen risk analiz yöntemi, Analitik Hiyerarşi Süreci (AHS) ile Büyükada için ağırlıkları tanımlanan ve kentsel kültür mirası alanlarında en çok hasar veren doğal afetlerden deprem, yangın ve sel risklerini içermektedir. Bu kapsamda analizler şu bileşenlerden oluşmaktadır: Deprem riski analizi; zemin tehlike analizi, tsunami tehlike analizi ve yapısal hasargörebilirlik analizini: Yangın riski analizi; yangın çıkış riski analizi ve yangın yayılma riski analizini; Sel/su baskını riski analizi; aşırı yağış nedeniyle oluşan su baskını riskinin analizi ve su toplama yapılarının hasar görmesi sonucu oluşan su baskını analizini içermektedir. Büyükada örneğinde baraj gibi su toplama yapıları bulunmadığından yalnızca su dağıtım hatları ve aşırı yağışa bağlı olarak eğim ve zemin özellikleri nedeniyle gerçekleşebilecek su baskını için riski analizi yapılmıştır. Analiz kapsamında belirlenen risk faktörleri ve bunların AHS ile oluşturulan ağırlıklarına bağlı olarak her bir risk için ayrı ve toplam riske yönelik CBS ortamında risk haritaları hazırlanmıştır. Büyükada'da doğal afetlerden kaynaklanan risklerin analizi sonucunda toplam tescilli yapı parsellerinin alansal olarak % 40.2'sinin, çok yüksek fiziksel çevre kaynaklı risk altında olduğu görülmüştür. Anahtar Kelimeler: Kentsel kültür mirası, doğal afetler, risk analizi, CBS, AHS, İstanbul-Büyükada. Existing issues in the research area of risk mitigation for urban cultural heritage in Turkey are mainly attributable to absence of a common and defined risk management system among the stake-holders that are responsible from risk mitigation at historical urban environments. Within this context this paper aims, to define a risk analysis system based on Analytic Hierarchy Process and spatial analysis methods within Geographic Information Systems-GIS that would guide for analysis of natural disaster related risks that threaten urban cultural heritage. Suggested methodology is implemented within Büyükada context. The sources of risks that threaten urban cultural heritage can be categorized such as physical, social, economic, political and technical /organizational however; it should also be noted that there are risks that can be a combined result of different categories of risk and not to mention that risk in itself is a multi layered concept. For instance a privately owned cultural heritage building might long be neglected due to different preferences of the owner and when it is demolished by an earthquake, the causative reason for this, is rooted in both the socio-cultural and the physical environment related risk factors. In Turkey, urban cultural heritage is under risk at many different levels. Aside from high earthquake risk, flooding and fire, other risk factors generated by political, social or economic factors include recent examples of Hasankeyf, an archeological heritage site that will be flooded by the completion of the Ilisu Dam; a conservation attitude that has been demoted to just keep the facades of heritage buildings in Tarlabaşı. Risk analysis for urban cultural heritage includes following steps: Analysis of existing structures and natural environment; Defining main risk sources and related risk factors for the heritage area; Prioritizing the causative risk factors and evaluating their weightings and rank; Evaluating each risk source independently and overall evaluation. Risks that are caused by natural disasters such as earthquake, flood and fire are among the costliest and most hazardous risks for heritage areas. Therefore risk analysis focuses on these natural disasters. Earthquake, fire and flood have been chosen among the risks that are caused by factors related to the physical environment. Within earthquake risk analysis: “Ground hazard analysis” where geological structure and their possible earthquake behavior is analyzed; “Tsunami hazard analysis” is made as an integrated analysis of possible earthquake affect through the sea topography, bathymetry and “Structural vulnerability analysis” is conducted where building behavior is assessed regarding to building type and condition. Fire risk analysis is combined of fire ignition and fire spread risk analysis. Fire ignition risk analysis includes analysis of explosive or flammable usage and areas. Fire spread risk analysis factors that affect the spread of the fire such as vegetation type and density, wind and slope. Within flood risk analysis, ground hazard analysis and vulnerability analysis of water distribution structures are made. Ground hazard analysis includes the geological formation that affects the permeability of the ground and topography of the area. Vulnerability analysis of water distribution structures includes the damage and the possible affected area that is around these structures. For Büyükada since there is no water collecting structures such as dams. Only ground water capacity analysis has been made. Risk factors are examined and their weightings have been defined for each risk with AHP in order to form raster image with spatial analysis within GIS for each risk sector. Risk analysis for Büyükada shows that %40,2 of all urban cultural assets are under very high risk of natural disasters. Fire and earthquake is more likely to cause damage on the overall Büyükada and urban cultural heritage. Earthquake risk is high due to ground properties, location of fault line and condition of existing building stock. Fire risk is rooted from high proportion of wooden structures, located close to dense forest area and fire ignition spots such as electricity distribution stations and LPG storage units. Adalar fire brigade is located on a high tsunami risk area, which might cause a secondary risk for uncontrolled fire at an event of earthquake and tsunami. Büyükada risk analysis reveals the most problematic areas, which would be beneficial in prioritizing resources within risk mitigation processes. Büyükada is isolated and carrying disadvantages of being an island, therefore the system and the infrastructure should be self-sufficient. Keywords: Urban cultural heritage, natural disasters, risk analysis, GIS, AHP, Istanbul-Büyükada
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