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Comparison of processes applied to cotton fabrics in order to reach high carboxymethyla-tion level
Get PDFTekstil malzemeleri, doğal olarak sahip olmadıkları özelliklerin kazandırılması veya kendilerinden beklenen ilave özellikleri sağlamak üzere kuru ve yaş işlemlerle terbiye edilirler. Pamuk lifinin ve dolayısıyla da pamuklu kumaşların doğal olarak sahip olmadığı buruşma dayanımı da bu özelliklerden birisidir. Pamuğa buruşmazlık özelliğinin kazandırılmasında konvansiyonel olarak kullanılan yöntem pamuğun N-metilol türevleri ile çapraz bağlanmasıdır ve bu yöntem kalıcı ütü olarak bilinmektedir. Bu uygulama ile kumaşa ayrıca boyutsal dayanım da kazandırılmaktadır. Ancak bu uygulamanın birçok dezavantajı da bulunmaktadır. Bunların başında muamele edilen kumaşın karsinojen olduğundan şüphe edilen formaldehiti açığa çıkarması, mukavemet kaybetmesi ve beyazlık seviyesinin düşmesi gelmektedir. Kalıcı ütüye alternatif yöntemler ise pahalı kimyasalların kullanılmasını içermektedirler. Bu nedenle daha kolay ulaşılabilen, daha ucuz kimyasallar kullanılarak ve kumaşın sahip olduğu özellikleri olumsuz etkilemeyen ve ayrıca formaldehit açığa çıkartmayan bir buruşmazlık terbiyesine ihtiyaç vardır. İyonik çapraz bağlama bu özellikleri sağlamaya aday yeni bir yöntemdir. İki aşamalı muamele içeren bu yönteme göre kumaş ilk aşamada karboksimetilasyon ile anyonik özellik kazanmakta, ikinci aşamada ise katyonik bir kimyasal ajan ile çapraz bağlanmaktadır. Bu çalışmada, pamuklu kumaşta yüksek karboksimetil seviyesine ulaşmak için yapılan karboksimetilasyon işlemindeki bazı parametrelerin etkileri incelenmiştir. Elde etilen sonuçlar, daldırma-kurutma-kondenzasyon işleminin daldırma-kondenzasyon, daldırma-kurutma-daldırma-bekletme ve daldırma-bekletme yöntemlerine kıyasla pamuğun karboksimetil seviyesini daha fazla arttırdığını göstermektedir. Ayrıca, işlem sürelerinin azaltılması için kurutma ve kondenzasyon sırasında hava akışının da gerekli olduğu görülmüştür. Anahtar Kelimeler: İyonik çapraz bağlama, pamuk, kalıcı ütü, buruşmazlık, karboksimetilasyon.Textile materials are treated using dry or wet finishing in order to impart the properties which they do not have naturally or which they are expected to have additionally. One of these properties is wrinkle recovery that cotton fiber and thus cotton fabric do not have naturally. The conventional method used in imparting cotton wrinkle recovery is crosslinking cotton with N-methylol derivatives and this method is known as durable press. In this method, the cellulose chains are covalently bond together by crosslinking and these covalent bonds cannot be disrupted by water. In a typical crosslinking process, a dry fabric is impregnated with a mixture of crosslinking agents and reaction auxiliaries by means of a foulard. The fabric is mildly dried and then cured on special machines. The pre-polymers either crosslink to form long chains of resin or link to the fiber surface. Initiation of condensation requires addition of acid and the reaction temperature has to be high. Crosslinking processes may be classified into two groups according to the state of the fabric just before the reaction. First one of these is dry crosslinking process that is by far the most applied process. In dry crosslinking; a dry fabric is impregnated with a mixture of the polymer resin, auxiliaries and catalysts. It is then dried and cured to enable the condensation of the resins. Durable press treatment imparts dimensional stability to cotton fabric as well. But it has some negative effects on cotton fabric too. Some of these negative effects are release of formaldehyde, which is a suspected human carcinogen, high level of loss in strength and in whiteness. These negative effects on cotton fabric can be vital especially depending on the end use of the fabric. For this reason, an alternative to durable press finishing is needed. This alternative should offer no or low release of formaldehyde, better strength retention and no or acceptable decrease in whiteness of the treated cotton fabric. The alternatives to durable press finishing offered so far include use of expensive chemicals. Some of these are dimethyl dihydroxy ethylene urea (DMeDHEU), dihydroxy dimethyl imidazolidinone (DHDMI), polycarboxylic acids such as citric acid and butane tetracarboxylic acid, with hyposphosphite salts, imidazoles or sodium maleate, sodium tartrate or sodium citrate as catalysts and citric acid as extender. Other systems based on polyacrylics, polyurethane and silicones are also offered. Reactive polymeric silicones appear to be interesting as they impart simultaneously non-creasing, waterproof, soil-release properties. These zero-formaldehyde finishing systems do not appear to compete with DMDHEU-type products because of their higher cost. By adding suitable additives such as polyhydric alcohols, phosphorous catalysts or sodium salt of hydroxyl acids, the cost of these finishing systems may be reduced. However, the molecular weight and thus the strength of the fabric decreases, yellowing of the fabric increases and the finish is less durable. An alternative which includes use of more available and cheaper chemicals, which causes no release of formaldehyde and which does not decrease strength and whiteness or at least which offers acceptable levels of decrease is needed. Ionic crosslinking treatment is a good alternative which has the potential to fulfill these requirements. This treatment uses available chemicals which are cheap and after this treatment the cotton fabric does not release formaldehyde as the chemistry used is completely different than that of durable press finishing. Ionic crosslinking is a two-step treatment of cotton fabric. The first step involves imparting anionic character to cotton by carboxymethylation. In this step, cotton fabric is generally treated with NaOH and then with Na salt of chloroacetic acid. The concentration of Na salt of chloroacetic acid used depends on the final level of carboxymethylation that is needed. The second step involves ionic crosslinking of carboxymethylated cotton by using a cationic agent. In this study, we investigated the effects of some process parameters of carboxymethylation treatment of cotton in order to reach high carboxymethylation content. Our results showed that use of pad-dry-cure treatment results in higher carboxymethylation level when compared with those of pad-cure, pad-dry-pad-batch and pad-batch. Moreover, we showed that air flow during drying and curing is necessary in order to shorten process times. Further in this study we will investigate the effects of carboxymethylation methods on wrinkle recovery angle performance of ionic crosslinked cotton fabric. Keywords: Ionic crosslinking, cotton, durable press, wrinkle recovery, carboxymethylation
Investigation of accuracy of land cover data used in regional climate modeling
Get PDFArazi yüzeyi iklim modellerinin anahtar elemanlarından olup, yüzeydeki enerjinin hissedilebilir ve gizli ısı olarak, yüzeydeki mevcut suyun ise buharlaşma ve akış olarak bölüşülmesini kontrol etmektedir. Ayrıca, arazi yüzeyinin pürüzlülüğü ve yüzeyin cinsine bağlı olarak ısı kapasitesi ve momentum tutulma miktarı değişmektedir. Bu nedenle arazi yüzeyinin doğru ve güvenilir bir şekilde ifade edilmesi iklim çalışmaları için önemlidir. Bölgesel iklim modellerinin çoğunda, global olarak hazırlanmış olan Global Land Cover Characteristics (GLCC) arazi örtüsü verisi kullanılmaktadır. Bu çalışmada, endüstrileşme ve nüfus artışı sonucunda özellikle 1980'li yıllardan sonra arazi örtüsü değişiminin meydana geldiği Marmara Bölgesi çalışma alanı olarak seçilmiştir. Çalışmanın ilk aşamasında, 2001-2005 tarihleri arasında elde edilen Landsat7 ETM+ görüntüleri radyometrik ve atmosferik olarak düzeltilerek atmosferik parçacıklardan kaynaklanan bozulma etkileri ve sistematik hatalar elemine edilmiştir. Geometrik distorsiyonları elemine etmek, piksel bağıl konum hatalarını düzeltmek ve görüntüleri ortak bir koordinat sisteminde tanımlayabilmek amacıyla her bir görüntü geometrik olarak düzeltilmiştir. Görüntüler farklı yöntemler kullanılarak sınıflandırılmış ve çalışma bölgesi için arazi örtüsü haritası oluşturulmuştur. Oluşturulan arazi örtüsü haritası, GLCC verisi ile kıyaslanarak bu verinin Marmara Bölgesi için doğruluğu araştırılmış ve verideki eksiklikler belirlenmiştir. Çalışmanın sonucunda GLCC veri setinin güncel olmadığı ve Marmara Bölgesinin önemli bir kesimini doğru temsil etmediği tespit edilmiştir. Bölgesel iklim modelleme çalışmaları için, bu veriye alternatif olarak daha doğru ve güncel olan Landsat ETM+ görüntülerinden üretilmiş arazi örtüsü verisinin kullanılabileceği gösterilmiştir. Anahtar Kelimeler: Arazi örtüsü, arazi yüzeyi, bölgesel iklim modelleme, uzaktan algılama, Landsat7 ETM+.In this research, utilization of Landsat7 ETM+ images in regional climate modeling was investigated and the accuracy of Global Land Cover Characterization (GLCC) data set used in regional climate modeling was assessed for the Marmara Region by comparing these data with Landsat ETM+ derived land cover data. Marmara Region was selected as study area because it faced with significant land cover changes as a result of rapid industrialization and population increase especially after 1980s. The region occupies the northwest corner of Turkey with a surface area of 67 000 km² and represents approximately 8.6% of the Turkish national territory. It is the smallest but most densely populated of the seven geographical regions of Turkey. This region includes eleven cities namely Istanbul, Bursa, Kocaeli, Edirne, Balikesir, Kirklareli, Tekirdag, Canakkale, Bilecik, Sakarya and Yalova, where first three cities are industrial and commercial centers of Turkey. Landsat7 ETM+ images obtained between 2001 and 2005 were used to derive land cover data of the Marmara Region. Since 2005 Landsat ETM+ frame includes the significantly changed areas of the Marmara Region like Istanbul and Bursa, it is assumed that created land cover data is representing the year of 2005. In addition to satellite images, forest maps, 1/25 000 scaled topographic maps, ground surveys and photographs were used to assist geometric correction and classification procedure. At the first stage of the research, all images were atmospherically and radiometrically corrected to minimize contamination effects of atmospheric particles (scattering and absorption effects due to the atmosphere) and systematic errors. Then, geometric correction was performed for each image to eliminate geometric distortions, correct errors in the relative positions of pixels, and define images in a common coordinate system. A new approach, semivariograms, was introduced to select appropriate band combinations for studying different land cover classes. After these corrections, images were classified using different classification methods to identify different land cover types. United Stated Geological Survey (USGS) Land Use and Land Cover Classification Legend was used in the study. Several pilot areas were created and classification employed separately for these areas to minimize the spectral mixing of various classes such as barren, crop and urban and increase the classification accuracy. The classification results were aggregated to 1 km to form final land cover data and classification accuracy assessment was performed on final land cover data. At the second stage of the research, 2005 land cover data obtained from Landsat7 ETM+ images was compared with the GLCC data set to analyze the accuracy of these data for the Marmara Region. These data have been used in many regional climate models like Regional Atmospheric Modeling System (RAMS), the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) and Weather Research and Forecasting (WRF). It was obtained from 1-km Advanced Very High Resolution Radiometer satellite images spanning April 1992 through March 1993 with an unsupervised classification technique and accuracy assessment of data set was not performed globally. Land surface is a key determinant in climate system and it controls the partitioning of available energy at the surface between sensible and latent heat, the partitioning of available water between evaporation and runoff. Therefore it must be represented accurately and precisely. Land cover products used in most climate models were initially compiled from maps and ground surveys till the global scale land cover products generated from remote sensing images became avaible. These remotely sensed derived global land cover products like GLCC, University of Maryland land cover classification and Global Land Cover 2000 have been implemented into various land surface schemes and climate models. However, no land cover data set is 100% accurate, even if developed from the most advanced satellite images. The results of comparison analyses between Landsat derived land cover and GLCC show that GLCC data is not up-to-date and have deficiencies and inaccuries in some parts of the Marmara Region. GLCC is not representing urban areas accurately in İstanbul, Adapazari, Bursa and İzmit. These data also have problems in coastal part of İstanbul European side and show some forest areas as crop areas. This research results show that land cover data obtained from Landsat ETM+ images can be successfully and accurately represent the study region therefore it is an alternative source of up-to-date and accurate land cover data for regional climate modeling. Keywords: Land cover, land surface, regional climate modeling,remote sensing Landsat7 ETM+
Managing knowledge for business excellence: Knowledge Focused Six Sigma (KFSS)
Get PDFAltı Sigma programını hayata geçirmeye karar veren kuruluşlar, programın başarısı için gerekli bilgiyi elde etme ve içselleştirme ihtiyacı duyarlar. Altı Sigma için belirlenen kritik başarı faktörlerinin yanı sıra bilgi yönetimi prensiplerinin göz önünde bulundurulduğu sistematik bir uygulama, programın başarısına katkıda bulunacaktır. Bu amaçla, müşterinin sesinden başlayarak süreçlerde yapılacak düzenlemelere kadar, tasarım öğeleri arasındaki ilişkilerin incelenmesine ve böylece sorunsuz tasarımlar yapılmasına destek veren Aksiyomlarla Tasarım yönteminin kullanılması kararlaştırılmıştır. Aksiyomlarla Tasarım yöntemi kullanılarak, Altı Sigma Altyapısının isterleri, bileşenleri ve bilgi süreçleri arasında ilişkiler matrisler yardımıyla incelenmiş ve tasarım öğeleri Aksiyomlarla Tasarım prensiplerine uygun şekilde düzenlenmiştir. Bu düzenleme ile Yayılım, İyileştirme ve İçselleştirme kriterlerini içeren Bilgi Odaklı Altı Sigma (BOAS) metodolojisi ortaya çıkmıştır. BOAS metodolojisi ile Altı Sigma programı kritik başarı faktörlerinin göz önünde bulundurularak Altı Sigma altyapısının isterlerinin hayata geçirilmesi için odaklanılması gereken bilgi süreçleri ile iyileştirmeye açık alanlar ve olası etkileri görülebilmektedir. Kuruluşların Altı Sigma programlarını değerlendirmelerine imkân veren BOAS metodolojisi, Yayılım, İyileştirme ve İçselleştirme kriterleri için yaklaşımların değerlendirilmesine yönelik nasıl soruları ve sonuçların değerlendirilmesine yönelik göstergeleri içermektedir. Yaklaşım ve sonuçlar için elde edilen puanlar, aksiyomlarla tasarım yöntemi ile ilişkilerin incelenmesi sırasında kullanılan matrislerden elde edilen ağırlıklarla çarpılarak toplanmakta ve kuruluş için Altı Sigma Entelektüel Sermayesi hesaplanmaktadır. Anahtar Kelimeler: Bilgi yönetimi, Altı Sigma, aksiyomlarla tasarım, entelektüel sermaye.Fierce competition forces organisations to implement various improvement methodologies at a time. However, each of these methodologies proposes their own approach or philosophy. The situation may be confusing for the decision makers as they may confront different roadmaps for similar objectives. In order to make best use of scarce resources, strategies should be formulated for aligning these methodologies. Leadership must give careful thought as to how the various overlapping activities can best be organised to optimise their impact on performance. It is observed that many organisations pursuing a methodology for designing and improving their processes decide to apply Six Sigma. Six Sigma enables organisations improve their processes and produce value added, low-cost products and services by using statistical tools within a structured roadmap. Statistically, six sigma means 3.4 defects per million opportunities, whereas in management terms, Six Sigma is an improvement methodology, which aims to reduce the cost of poor quality and increase profitability by exceeding customer expectations through focusing on the effectiveness and efficiency of the processes. Six Sigma leads to a cultural transition, as it underpins solving problems by means of data driven scientific tools. Naturally, organisations, deciding to start a Six Sigma program, need to acquire the essential knowledge about the tools and create a suitable environment for the cultural transition. Organisations initiating an intensive program like Six Sigma usually have to buy the knowledge and make costly consultancy investments while deploying the program all through the organisation. They need to define new roles and responsibilities and try to manage projects systematically in order to increase the efficiency of methodology. The need for an infrastructure to maximise the benefits and to internalise the methodology emerges eventually. Practitioners have pursued a systematic approach in order to align the program with the corporate culture; accordingly, researchers have made various publications, listing the critical success factors of a successful Six Sigma deployment, or the reasons of a failing Six Sigma program. Unfortunately, most of these valuable studies neither enlighten the practitioners about the relations or the sequence of the factors nor introduce an approach, which is systematically designed, for instance, by using a methodology adopted also by Six Sigma. As a result, to design the new methodology, it is decided to use axiomatic design, a design methodology, which is also one of the tools mentioned in Design For Six Sigma (DFSS), so that the relations among critical success factors, the requirements from the Six Sigma infrastructure, the components of the Six Sigma infrastructure and knowledge processes can be elucidated for the practitioners. The methodology, designed using axiomatic design, is called Knowledge Focused Six Sigma(KFSS). The criteria of KFSS are defined in accordance with the components of the design. The criterion for "creating Six Sigma deployment knowledge" by using "upper management support" for "deploying the Six Sigma program" is called the "Initiate" criterion. How "Six Sigma knowledge, created within 'Six Sigma projects', is applied" for "improving processes", is studied within the "Improve" criterion. The "Internalise" criterion focuses on "utilising Six Sigma deployment and training knowledge" within "an accepted and customised Six Sigma program" for "internalising the methodology". KFSS methodology comprises two parts for assessing Six Sigma Intellectual Capital: Approaches and Results. For assessing the approaches, how questions are asked. The questions are designed to explore the implementation level of relevant knowledge process in order to achieve requirements from the Six Sigma infrastructure. Answers for how questions are scored by using the scoring guidelines provided for three dimensions: quality, systematic approach and deployment. For assessing results, a set of predefined indicators is used. The indicators are grouped as effect, activity and resource indicators. Effect indicators focus on "what happens", whereas activities indicators focus on "what is done" and resources indicators focus on "what is created". All indicators are arranged in order to make 100 the best performance. Result scores are granted in line with the performance of the organisation for these indicators. By using approach and result scores and the weights calculated through relationship matrices, Six Sigma Innovation Capital, Six Sigma Process Capital, Six Sigma Human and Relationship Capital are calculated. Six Sigma Intellectual Capital is calculated In line with the defined importance for Six Sigma Innovation Capital, Six Sigma Process Capital and Six Sigma Human and Relationship Capital. Keywords: Knowledge management, Six Sigma, axiomatic design, intellectual capital
Effect of disturbance on 1D compression behavior of Samsun-Carsamba blue clay
Get PDFZeminlerin ek bir yüke maruz kaldıklarında sergileyecekleri zamana bağlı sıkışma davranışının önceden belirlenmesi geoteknik mühendisliği açısından büyük önem taşımaktadır. Yumuşak kil zeminler üzerinde inşa edilecek yapının ömrüne bağlı olarak mühendisin, toplam oturma hesabına birincil konsolidasyonun yanı sıra ikincil ve üçüncül sıkışma miktarlarını da katması gerekebilmektedir. Üçüncül sıkışmalar, her kil zemin türünde görülmemekle birlikte, özellikle organik zeminlerde büyük mertebelere ulaşabilmektedir. Bu çalışmada, üçüncül sıkışma davranışı sergileyen Samsun-Çarşamba Mavi Kili ile çalışılmıştır. Dane çatısının örselenmesinin üçüncül sıkışmalar üzerindeki etkisi araştırılmıştır. Bu kapsamda örselenmemiş ve yoğrulmuş kil numuneleri üzerinde klasik konsolidasyon deneyleri ve 7 adet uzun süreli konsolidasyon deneyi yapılmıştır. Deneyler sonucunda; örselenmenin birincil konsolidasyonun tamamlanma tp süresini uzattığı, cv katsayısını düşürdüğü, s¢p önkonsolidasyon basıncını azaltarak belirsizleştirdiği, tekrar sıkışma indisini Cr artırdığı, sıkışma indisini Cc azalttığı belirlenmiştir. Ayrıca, örselenmeyle örselenmemiş numunelerde belirlenen ikincil sıkışmanın tamamlanma süresinin ts kısaldığı, ikincil sıkışma katsayısı Ca değerinin %30 oranında arttığı, Ca/Cc oranının etkilenmediği görülmüştür. Örselenmenin üçüncül sıkışma katsayısını Caet düşük gerilmelerde 4.5 kat artırdığı, gerilmenin artmasıyla bu artışın kaybolduğu bulunmuştur. Uzun süreli konsolidasyon deneylerinde, ikincil ve üçüncül sıkışmalar sırasında örselenmemiş ve yoğrulmuş numunelerin sıkışma eğrilerinde Samsun Çarşamba Mavi Kilinde yaşlanma, yıkanma veya çimentolanma yönünde herhangi bir bulguya rastlanmamıştır. Anahtar Kelimeler: Konsolidasyon, ikincil sıkışma, örselenme. In Turkey, housing problem due to rapid increase of human population and immigration to big cities enforces the municipalities to allow the sites having unfavourable geotechnical soils for settlement. Moreover, the requirement for large areas makes the lowlands with thick alluvial soil deposits be used for the structures like airports. Generally, high ground water causes low bearing capacity and high compressibility in soft clays in these types of soil deposits. One of the examples of these types of problems in Turkey is the settlement problem at Samsun-Carsamba International Airport that has been constructed on Samsun-Çarsamba plain of Black Sea region. During the construction stage of the airport the site explorations illustrated that the settlement problems would occur in the soil profile at the runway sections containing a soft blue clay layer named as Samsun-Carsamba blue clay. It was decided to improve the clay layer by preloading that existed below the 20 000 m2 area at the beginning of the runway. The settlement observations during the one year preloading period showed that tertiary compression would also occur not only in organic soils and peat, but also in soft clays. Wet sieve analysis illustrated that the grain size distribution of Samsun?Carsamba blue clay is 41% silt and 59% clay. The mineralogical investigations on the samples illustrated that clay grain size minerals consist of 40 - 50% Ca-montmorillonite, 30% calcite + quartz and 10% kaolin. The index properties of the clay are that consistency limits; liquid limit wL = 73 %, plastic limit wP = 29 % specific unit weight gs = 27.6 kN/m3, and natural water content wn = 65%. According to the Unified Soil Classification System the clay has been classified as high plasticity clay CH. Generally, the secondary compression of a soil at a constant effective stress is commonly attributed to collapsing of the soil fabric. On the other hand, what causes the tertiary compression is still not well defined. In the scope of this study the effect of disturbance on time dependent compression behaviour of Samsun-Carsamba blue clay has been investigated. For this purpose 2 conventional consolidation tests and 7 long-term consolidation tests that lasted 3 to 8 months were performed on undisturbed and remoulded samples. In the conventional consolidation tests where Load Increment Ratio LIR=1 and Load Increment Duration LID=24 hours, it has been found that remoulding decreased the initial void ratio. Furthermore, by remoulding, end of primary ( EOP ) e-log s¢v compression curves shift to downward, preconsolidation pressure becomes uncertain and at every stress level primary consolidation last longer. Moreover remoulding of Samsun-Carsamba blue clay sample increases recompression index ( Cr ) and decreases compression index ( Cc ). At every stress level remoulding causes a decrease on consolidation coefficient ( cv ) values for undisturbed and remoulded samples. On undisturbed samples around preconsolidation pressures the 2 ~ 3 times reduction of cv has been observed, whereas on remolded samples this has not been the case. On undisturbed and remoulded samples, 7 long-term consolidation tests have been performed. Each test included a creep test that lasted 70 - 234 days at various stress levels ranging from 25 kPa to 400 kPa. As a result, the dispersed structure at remoulded sample illustrated more resistance towards flowing than the flocculated structure at undisturbed sample, so remoulding increases the primary consolidation time ( tp ). Furthermore, remoulding decreases the end of secondary compression ( ts ) or the initial time of tertiary compression. By remoulding the variation of secondary compression coefficient (Ca ) and Ca / Cc ratio is negligible. For undisturbed samples as the effective stress increases, tertiary compression ratio ( Ct ) gradually increases whilst for remoulded samples the greater Ct values at lower stress levels decreases. During a long-term consolidation test up to the creep test stress level loading steps were carried out according to LIR = 1. To investigate the post compression behaviour of Samsun-Carsamba blue clay after creep tests, the samples have been loaded by small load increments ( LIR 1 ) gradually but no aging, leaching or cementing effects have been observed on v - log ¢v graphs of undisturbed and remoulded samples. Keywords: Consolidation, secondary compression, disturbance
Possibilistic linear programming approach for fuzzy Supply Chain Planning
Get PDFSon yıllarda, küreselleşmeyle artan rekabet ile birlikte, Tedarik Zinciri Planlamanın (TZP) önemi artmaktadır. Bu nedenle; TZP’de stratejik kararlarının verilmesi çok büyük önem taşımaktadır. Gerçek problemlerin hepsinde görüldüğü gibi, tedarik zincirinin ilgili süreçlerinde de belirsizlikler ile karşılaşılmaktadır. Bundan ötürü; TZP modellerinde belirsizliklerin göz ardı edilmemesi gerekmektedir. Literatürde TZP’deki belirsizlikleri modelleyen çalışmalarda uzun dönemli stratejik kararların kesin olarak verildiği ve bunların orta ve kısa vadede revize edilmeleri gerektiği tespit edilmiştir. Bu çalışmada, uzun dönemli kaynak atama, ürün tedariki ve üretim kararlarının verilebilmesi için bir Olabilirsel Doğrusal Programlama (ODP) modeli geliştirilmiştir. ODP modelini kullanmanın temel amacı, tedarikçi ilişkilerinde ve üretim planlamada esneklik sağlamak üzere bulanık kararların verilmesini olanaklı kılmaktır. Bu yüzden önerilen ODP’de, sadece talep ve verim oranları gibi kritik TZP girdileri değil aynı zamanda satış miktarı, üretim miktarı ve tedarik miktarı gibi karar değişkenleri de bulanık kabul edilmiştir. Önerilen ODP’nin amacı firmanın tedarik zinciri faaliyetleri sonucunda oluşan kârı en büyüklemektedir. Çalışmada ODP’yi çözmek için DP modeline çevrilmesi önerilmiştir. Bu amaçla girdi parametreleri ve karar değişkenleri üçgen bulanık sayılar ile ifade edilmiştir. ODP’de önerilen amaç fonksiyonu ve kısıtlar, üçgen bulanık sayılar için geliştirilen toplama ve çarpma işlemleri ile büyüktür/küçüktür ilişkileri ile DP’ye çevrilmiştir. Çalışmada ayrıca önerilen modelin etkinliği hipotetik bir örnek üzerinde gösterilmiştir. Anahtar Kelimeler: Tedarik Zinciri Planlama, olabilirsel doğrusal programlama, bulanık modelleme.The interest in Supply Chain Planning (SCP) has recently raised due to the fact that the opportunity of an integrated planning of the supply chain (SC) can increase the profitability, reduce production and outsourcing costs and enhance customer service levels, so that the enterprises can cope with increasing competitiveness introduced by the market globalization. A SC is an integrated system which synchronizes a series of inter-related business processes in order to convert raw materials into the specified finished products and distribute and promote these products to retailers or customers. Supply chain planning problems are due to uncertainties like the other real life problems. Uncertainties that affect the SCs can be categorized in two groups: (i) environmental uncertainties, and (ii) system uncertainties. Environmental uncertainties include supply quantity, raw material costs, lead times, and demand product price while system uncertainties contain operation efficiency, resource usage efficiency, labor cost, production capacity, and stock level. Among these uncertainty types, demand has been the most important and extensively studied source of uncertainty. The emphasis on incorporating demand uncertainty into the planning decisions is appropriate given the fact that effectively meeting customer demand is what mainly drives most SCP initiatives. Furthermore, demand is the main source of uncertainties as the fluctuations of it affects the production system and suppliers gradually. The main idea of the proposed model is to make uncertain and therefore flexible decisions to cope with the uncertainties revealed in strategic SCP. Demand affects system uncertainty in which some other types of uncertainty also exist. System uncertainty and supply uncertainty mutually affects each other. In this circumstances to make crisp decisions may cause irrelevant or irreversible long term decisions that will need huge revisions in medium or short term. In this paper a Possibilistic Linear Programming (PLP) model is proposed to support strategic decisions of the enterprises concerning the production resources utilization and outsourcing. In order to deal with the external and internal uncertainties fuzzy inputs and fuzzy outputs are considered. The problem examined in the paper is described as; Given: (1) A supply chain that is the integration of the focal enterprise, its current suppliers and customers, as well as the potential suppliers and customers, and related products, semi-products and raw materials (in the rest of the paper "product" will be used for these three concepts),(2) Resources used to produce the products as well as their costs and capacity levels,(3) Outsourced products and other outsourcing opportunities, as well as their costs,(4)Production and outsourcing yield rates of product. Using the inputs defined above, the model proposed helps the enterprise make decisions about the following strategic questions: (1) Which product should be produced internally? (2) Which resources should be utilized to the production of which product? (3) Which products should be outsourced, and how much? (4) Demands of which market should be satisfied? The proposed PLP contains fuzziness in some of the constraint parameters and in all decision variables. The objective of the PLP model is to maximize the profit of enterprise's SC facilities. To solve the proposed PLP model it is suggested to be transformed into a linear programming model, which can be solved easily with the least mathematical effort. Therefore the inputs and the decision variables of the model are represented by triangular fuzzy numbers. Then the summation, multiplication operations as well as the greater than and less than relations that are defined for triangular fuzzy numbers are employed to transform the PLP to a linear program. The proposed PLP model is then applied in a hypothetical example to evaluate the applicability and validity of the model and the solution methodology. As a result of the application it is realized that the uncertainty in the outputs depends on the uncertainty in the inputs. The uncertainty in the inputs affects both the uncertainty and the amount of profit. Under these circumstances the model aims to decrease the uncertainty on the decisions and increase the profit. Consequently model is proved to give satisfactory results. Keywords: Supply Chain Planning, possibilistic linear programming, fuzzy sets
The dynamic analysis of a vertical riser in the deep sea
Get PDF Bu çalışmada, rayserin yatay hareketi incelenmektedir. Rayser, platform veya teknede bulunan gerdirici aygıtı ile gerilmekte olan düşey asılı duran bir kiriştir. Bu kiriş; dalgalar, akıntı ve yüzen platform veya tekne hareketi ile zorlanmaktadır. Dördüncü mertebeden kısmi türevli hareket denklemi, Euler kiriş-kolon teorisi gözönüne alınarak, varyasyonel bir yöntem kullanılarak elde edilmiştir. Hidrodinamik kuvvetler, Morison Denklemi'nin düzeltilmiş bir şekli kullanılarak değerlendirilmektedir. Bu denklem ampirik olmasına rağmen, rayser gibi hidrodinamik geçirgen açık deniz yapılarının dizaynında yaygın bir şekilde kullanılmaktadır. Lineer dalga teorisi, su parçacığının kinematiğinde kullanılmaktadır. Daha sonra, uzun rayserin statik ve dinamik analizi yapılmaktadır. Her iki analizde de, yönetici hareket denklemi Bessel diferansiyel denklemine dönüştürülerek çözüm aranmaktadır. Statik analizde kritik efektif boyuna kuvvet ve bu kuvvetin yeri de hesaplanmaktadır. Derin su analizinde, hidrodinamik kuvvetler dalga boyunun yarısı kadar bir derinlikten itibaren kayboldukları için, dalganın direnç ve atalet kuvvetleri gözönüne alınmamış, onun yerine yüzeyde dalgadan kaynaklanan surge hareketinin genliği sınır şartı olarak kullanılmıştır. Hazırlanan bilgisayar programlarının doğruluğu, statik ve dinamik analizler için kullanılan örnek veriler işlenerek karşılaştırmalı olarak gösterilmektedir. Daha sonra, Amerikan Petrol Enstitüsü’nün bültenindeki 1500 ft (457.2 m) su derinlikli konvansiyonel rayser incelenmiştir. Statik analizde API 1500-0-1, dinamik analizde API 1500-20-1-D olarak adlandırılan bu rayserin verileri kullanılarak bulunan sonuçlar, enstitünün test için sunduğu, dokuz bağımsız araştırmacı tarafından elde edilmiş birleşik sonuçların ortalaması ile karşılaştırılmıştır. Bulunan sonuçların bu sonuçlar ile uyumlu oldukları görülmektedir. Anahtar Kelimeler: Konvansiyonel rayserin yatay hareketi, Bessel diferansiyel denklemi, kritik efektif boyuna kuvvet, API 1500-20-1-D rayseri. Offshore technologies are used for exploration and production of oil, gas and mining and for the research and production of hydrothermal energy. Beside the conventional flexible risers, there are compliant production risers and the hybrid production risers as well. The lower end of the riser is connected to the top of the blow out preventer with a ball joint. The upper end of the riser is connected with a small pipe extended from the tensioner device. The vertical balance of riser is provided by the tensional force. The riser is forced by the waves, current and the motion of floating platform or a vessel. Development of the mathematical model, evaluation of hydrodynamic forces and application of a solution technique are the steps of the analysis. For the mathematical formulation; the material is assumed to be homogenous, isotropic and linear elastic. Considering Euler beam-column theory, the shear strength effect is neglected. The equations of motion are obtained using a variational method. The statements for flexural and torsional curvatures of deformed beam are expressed in terms of elastic displacements. The strain energy of the system is also obtained in terms of these curvatures. The nonlinear, coupled equations of motion are derived using Hamilton's principle. The effect of internal and external static fluid pressures is included into the model by using the concept of effective tension and weight. It is assumed that flow characteristics don't change in the direction of the flow due to the riser. This means that the incident wave kinematics remains same in the vicinity of the wave. As the riser is assumed as a hydrodynamically permeable structure, the hydrodynamic forces due to waves and currents are assessed using a modified form of the Morison equation. This equation is empiric, however, it is reliable in the estimation of wave forces on the slender structures as risers and widely used in the design of hydrodynamically permeable offshore structures. In Morison equation, the in-line forces are given as the sum of inertia and drag forces. Airy wave theory is used in the water particle kinematics. The static or dynamic problem can be solved in two forms: analytical and numerical. Using the numerical method directly, the fourth order governing partial differential equation is solved either by numerical approaches or by finite element procedures. The finite difference method and numerical integration processes are examples of numerical approaches. Numerical methods are more generic in studying risers with variable geometry such as added buoyancy modules. The forced dynamic problem is generally solved in two categories, deterministic or nondeterministic (stochastic) and the calculations are made in frequency and time domain. The frequency analysis is more appropriate for fatigue analysis, but for a solution the drag term is required to be linearized. Time domain methods are based on a simulation in time domain of hydrodynamic loads. Nonlinearity of drag forces is preserved in these methods. Therefore, they require more computing time. In the static and dynamic analyses of long risers, the governing equation of motion is transformed into a Bessel differential equation. The critical effective longitudinal force and the position of this force are also calculated. In dynamic analysis, the drag and inertia forces are ignored, because the effects of hydrodynamic forces are disappeared after half a wave-length depth. Instead of these forces, the amplitude of the surge motion is used at the surface in the upper boundary condition. The accuracy of computer programs made for static and dynamic analysis is shown with the results calculated by sample data. Then, the conventional riser in depth of 1500 ft (457.2 m) in the bulletin of American Petroleum Institute (API) is examined. This riser is called API 1500-0-1 and API 1500-20-1-D in static and dynamic analysis, respectively. The data for the given riser are used separately both in static and dynamic analysis. The results are compared with the mean of nine results which were presented for testing by API. Although the calculated results show some numerical differences from the API results in the location where is closer to the lower end of riser, the results by present method are in good agreement with those of API. One of the possible reasons of this is that the effects of current are ignored in this study. Keywords: Horizontal motion of the conventional marine riser, the Bessel differential equation, critical effective longitudinal force, API 1500-20-1-D riser
Fault detection based on coherence analysis for stator insulation in induction motors
Get PDFAsenkron motorlar bütün endüstriyel süreçler içinde en sık kullanılan elemanlardır. Endüstriyel sistemlerin ekonomik ve daha güvenli çalışabilmeleri için arızaların erken tespit edilmesi ve izole edilmesi çok önemlidir. Bu nedenle, endüstrinin birçok alanında kritik sistemlerde öngörülü bakım amaçlı olarak durum izleme çalışmaları yapılmaktadır. Durum izleme sayesinde elde edilen verilerin kullanılması ile aniden ve plansız olarak meydana gelen kesintiler önlenebilmektedir. Bu çalışmada, asenkron motorlarda stator sargısı yalıtım arızası göz önünde tutulmuş, stator yalıtımında arıza özellikleri suni olarak yaşlandırma işlemi uygulanarak oluşturulmuş ve veriler spektral analiz yöntemi ile analiz edilmiştir. Stator yalıtım arızasının temel spektral özellikleri 5 BG gücünde bir asenkron motora hızlandırılmış yaşlandırma uygulanması ile elde edilmiştir. Hedefe ulaşmak üzere, tek başına akım ve titreşim işaretlerine ait verilerle yapılan spektral analizlerle sargı yalıtım arıza tanısına ait belirgin sonuçlar elde edilememiştir. Stator akımı ve titreşim işaretlerinin arasındaki koherens yaklaşımı ile ise çift harmonik değerlerinde kuvvetlenmeler olduğu belirlenmiş ve bunların stator yalıtımı arızasının göstergesi olarak kullanılabileceği belirlenmiştir. Bir motora ait akım ve titreşim verileri ile elde edilen çıkarımlar, aynı deneye tabi tutulan iki eşdeğer motora ait verilerle yapılan analizlerle de doğrulanmıştır. Moment bilgisinin stator akımı ve dolayısıyla magneto-motor kuvvet (mmk) ile olan ilişkisine dayalı olarak titreşim işaretlerine yansıması dolayısıyla, akım-titreşim ilişkisinin daha belirleyici olacağı kararına varılmıştır. Bu çalışma, bu uygulamada 4. ve 16. harmonikler arasındaki çift harmoniklerin yalıtım arızasının en önemli imzası olduğunu göstermiştir. Anahtar Kelimeler: Asenkron motorlar, yaşlandırma işlemi, koherens, çift harmonikler, stator yalıtım arızası.Induction motors are the most frequently used components in almost every type of industrial processes. Early detection and isolation of faults that cause catastrophic system failure are crucial for more reliable and economic operation of industrial processes. For this reason, condition monitoring studies are performed for predictive maintenance purposes of the critical systems in most areas of the industry. Hence, sudden and unscheduled downtimes can be prevented by performing correct and timely maintenance activities using the information provided by condition monitoring studies. Through the statistical studies on induction motor failure distribution, it is reported that 40 % of all induction motor failures are caused by stator related faults such as insulation faults (Bonnett and Soukup, 1992). In the last two decades, the wide use of the motor drives based on the power electronics devices, caused current harmonics to occur and resulted in stator and bearing related problems. Hence, the use of motor drives creates some undesirable effects with the eventual failure of motors. In the related literature, there are several studies based on the stator degradation using the signal analysis methods for rotating machineries in recent years. Some of these investigators have reported the role of pulse-width modulated (PWM) devices on the stator winding insulation. They also indicate the effect of the even harmonics in the stator current of induction machines by using the spectral analysis approaches (Kueck, 2002; Filippetti, 2000). In this research, stator-winding insulation damage in induction motors is considered and fault features developed during the artificial aging process of the stator insulation are extracted from the collected data by the spectral analysis methods. Even harmonic effects are determined as a common feature between the phase currents and vibration signals using the coherence analysis and this feature indicates the stator insulation fault. This research is aimed to extract certain spectral features of the stator insulation damage based on an experimental study in the laboratory environment. This was determined by a signal processing application using the collected data. In order to get a database for induction motor failures from the experimental study, 5-HP, three phases, four poles induction motors are artificially aged by electrical methods. Several aging processes are performed. After each cycle of accelerated aging, the test motor was put on a motor performance test platform. From the experimental setup, high frequency data with a sampling frequency of 12 kHz were acquired and include 3-phase motor currents and voltages, rotor speed, torque, and six vibration measurements. The spectral analysis on the current signals is not so much informative. As an alternative approach, to determine the insulation failure, the cross approach which is defined between the current and vibration signals, is used. This new approach is the calculation of coherence function between the motor current and vibration signals regarding to the initial and aged cases. Hence the following functional relationship is calculated and it shows the effective harmonics with the huge amplitudes to extract the failure information related to motor insulation. Through the coherence analysis between the current signal and torque measurements for the initial and aged cases, the existence of all the harmonic components like the even and odd harmonics of the fundamental frequency at 60 Hz was clearly observed. Thereupon, the coherence application was used to reveal the relationship between motor current and vibration and then, as a result of this application, some special frequency values represented by the even harmonics of the line frequency at 60 Hz are determined at 240, 360, 480, 600, 720, 840 and 960 Hz. These even harmonics can be interpreted as the characteristic property of the insulation aging. These harmonics are present as a result of the stator current imbalances based upon the stator insulation damage occurring after the aging processes. These current imbalances act on the stator magneto motor force (mmf) and cause motor vibrations. Hence high correlated amplitudes in coherence variations as appeared in the figure 7(a) can be interpreted as indicators of the stator insulation damage. Results obtained by using time information of one of three motors have been analysed for remaining motors and similar results have also obtained for them. At the final part of the study, extracted failure features have been monitored by Artificial Neural Networks (ANN) method. Keywords: Induction motors, aging process, coherence, even harmonics, stator insulation faults
Hydrodynamic modeling of Beysehir Lake for 1998 water year
Get PDFBu çalışmada, Beyşehir Gölü’nün üç boyutlu hidrodinamik modeli kurulmuştur. Beyşehir Gölü Türkiye’nin en büyük tatlısu gölüdür. Kurulan hidrodinamik model; 1992-2001 su yıllarının ortalama akımlarını en iyi temsil eden 1998 su yılı için çalıştırılmıştır. Modelleme çalışmasında; Devlet Su İşleri’nden (DSİ) meteoroloji, hidroloji ve batimetri verileri, Elektrik İşleri Etüt İdaresi’nden (EİE) hidroloji ve Devlet Meteoroloji İşleri’nden (DMİ) de meteoroloji verileri günlük olarak temin edilmiştir. Bu çalışmada ELCOM (Estuary and Lake Computer Model) 3D modeli kullanılmıştır. Modele girdi olarak; günlük rüzgâr hızı, rüzgâr yönü, kısa dalga radyasyonu, hava sıcaklığı, bulutluluk oranı, nemlilik, hava basıncı, yağış, giren / çıkan akarsuların debileri ve giren / çıkan akışkanının su sıcaklığı verilmiştir. Ayrıca gölün batimetrisi modele, planda 103x85 ve düşeyde 10 parçaya ayrılarak oluşturulan 87550 grid yardımıyla dijital olarak tanımlanmaktadır. Model; sonlu hacimler metodu ile hesap yapmaktadır. Modelin çıktıları; su sıcaklığı ile akışkanın x, y ve z yönündeki hızlarıdır. Model sonuçlarını daha iyi analiz etmek amacıyla yazar tarafından Matlab dilinde programcıklar yazılmış ve bu programlar kullanılarak model sonuçları detaylı olarak irdelenmiştir. Modelden elde edilen su sıcaklık değerleri ile DSİ tarafından yapılan arazi ölçümleri kıyaslanmış, modelin yeterli doğrulukta olduğu gösterilmiştir. Kurulan model yardımıyla, göldeki su hareketi ve bu su hareketlerine etki eden parametreler belirlenmiştir. Ayrıca gölde modellenen hidrodinamik olayların yıl içi değişimi özetlenmiştir. Anahtar Kelimeler: Beyşehir Gölü, hidrodinamik modelleme, ELCOM 3D, göl yönetimi. In this study the hydrodynamic model of Beysehir Lake is established. The prepared three dimensional hydrodynamic model is run for an average one year long period (1998 water year). In addition this paper includes the basic equations and modeling techniques used in the modeling studies. The model considers the pressure, air temperature, the turning effect of the earth, the tide force, the saltiness, the wind force, and the surface heat exchanges, the effects of the incoming and outcoming rivers. In the modeling study; the meteorological, hydrological and bathymetry data is provided by DSI whereas EIE delivered the hydrological data and DMI the meteorological data. As inputs for the model simulations; wind speed, wind direction, short wave radiation, air temperature, cloudiness, humidity, air pressure, precipitation, in-and outflow discharges are considered in daily basis together with the digital bathymetry of the lake. The model is defined in the three dimensional cells. In the plan view from the top side there are 85 and 103 sections, horizontally and vertically, respectively. The lake is divided into 10 sections in depth; 8755 (85*103 = 8755) cells are formed and divided in the program. The selected grid dimensions satisfy the Courant-Friedrichs-Lewy (CFL) condition. The time interval is selected as 3600 seconds. The solution duration of the model becomes longer in case of decreasing the time interval and increasing the grid number. The longest river reaching the Beysehir Lake is the Sarisu River with Number 19-104. This river had the highest discharge on 30 March 1998 (10.5 m3/s). The discharge entries do not affect the lake in general. The mixtures are in the local level even for high discharge entries. The minimum and maximum water temperature differences obtained from the run of the program for the 1998 water year are shown in Figure 2. The stratification clearness is high parallel to the increase in the difference between maximum and minimum temperatures. Either water motions or stratification occurs because of the density difference caused by the water temperature change on the lake. For example, the stratification increases if the water in the upper layer cools and causes to a mixture if it gets warmer. These mixtures and stratifications may occur both horizontally and vertically. With the help of the model, the water motions on the lake and the parameters affecting the water motion have been determined. Besides, the change of the hydrodynamic events on the annual basis has been summarized. The elements which form a lake, their characteristics, and the parameters affecting these elements are summarized. The loops in the lake, the stratification and the characteristics of the mixture are explained, the affecting external parameters are defined and the basic connections between them are presented. The validation tests are applied to the models and it is shown that the fit between the model and the data is sufficiently well. In addition the parameters effective in the models are investigated and their affects are summarized. The water temperatures obtained from the model are compared with the water temperatures measured by DSI. This comparison is presented in Figure 7. If the R2 value obtained by Equation 4 is close to 1 then the model results are close to the observed values (Bayazıt, 1996). In this study R2 value is found as 0.956. The results obtained can be summarized as follows: - The opposite stratification occurring in the winter is quite obvious, The stratification in the summer months is relatively weak, Beysehir Lake is a dimictic lake,The first three parameters affecting the model are; the precipitation, moisture and wind velocity,The river entries and the discharge abstractions are not effective in the whole lake,The shallow sections of the lake reacts with the external affects in a shorter duration, i.e. the changes in the air temperature cause the warming or cooling of the water. So vertical stratification occurs in the lake. Keywords: Lake Beysehir, hydrodynamic modeling, ELCOM 3D, lake management. 
Türkiye sularına uygun bir balıkçı gemisinin akım görüntüleme deneylerinin analizi
Get PDFIt is possible to see flow characteristics by inserting some measurement tools into any fluid flow. Furthermore, various methods are applied to make a flow visible. These methods are generally collected in two different groups. One of these groups is known as Surface Methods. The main surface methods used in flow visualization tests are as follows:A method of any substance dissolves in the fluid,A method of a mixture of oil and dye,The tuft method Generally, the surface methods are used in ship hydromechanics. Especially, the tuft method is applied widely. In this method, the streamlines near and on a body are determined by using tufts. In this study, the flow visualization tests of the model 148/1C of the parent fishing boat 148/1 were carried out with the appendages and model propeller. In the loaded condition, some geometrical characteristics of the model used in the tests are as follows: The ratio of geometrical similarity, a is 25/3, the length, L is 2.4 meters and the block coefficient, CB is 0.378. The tuft method was applied as flow visualization method in this study. The tests were carried out in the Circulating Water Channel at Ata Nutku Ship Model Testing Laboratory operating within the faculty of Naval Architecture and Ocean Engineering at Technical University of Istanbul. The circulating water channel is largely used for flow observations and specialist tests in steady forward motion under the atmospheric pressure. The test section of the channel is 1.5 meters x 0.75 meters and maximum speed is 2 meters/second. The channel is equipped with a mechanical resistance dynamometer and Pitot tubes for velocity measurements. Flow visualization tests are also frequently performed using wool-tufts and dye injection. All tests were carried out in the loaded condition (1.00xT) and highly loaded condition (1.25xT). The tufts used as flow visualization material were prepared from orlon yarns. In ten stations system, the pins with 1 millimeter diameter and 25 millimeters length were stuck with proper spaces on the stations 0, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 8.5, 9, 9.5, 10 and the rudder axis at the portside of the model. The limits of the pins are out of the boundary layer and the pins are perpendicular to the surface of the model. The color of the tufts within the boundary layer was selected as claret red and the color of the tufts out of the boundary layer was selected as orange. The lengths of these tufts are varies between 25 millimeters and 40 millimeters. The tests in the loaded condition were carried out in the 110 value of flow potentiometer (vm=1.4 m/s; Vs=8 knots) and 0, 50, 55 values of propeller potentiometer (RPSm=0, 29.4, 32.3; RPSs=0, 10.2, 11.2). The tests in the highly loaded condition were also carried out in the 110 value of flow potentiometer (vm=1.4 m/s; Vs=8 knots) and 0, 55 values of propeller potentiometer (RPSm=0, 32.3; RPSs=0, 11.2). The photographs were taken with a digital camera for all the test conditions. Then, a computer aided evaluation of these photographs was performed and the conclusions are presented here. The conclusions for the loaded condition are as follows (the values of flow and propeller potentiometers are 110 (Vs=8 knots) and 55 (RPSs=11.2) respectively): The flow lines in the stations 9, 8.5 and 8 are regular. The flow is normal in the region from the station 8 to the station 5. In the station 2, the flow is normal. In the station 1, there is turbulence at the region over the propeller. Furthermore, there is suction over the propeller and a vortex tube was observed there. There is suction in the stations between 1.5 and 1. Here, the tufts oscillate. Bubbles on the surface of the model were also observed. There is a backward flow on the surface of the model in the propeller disk plane. In the region between the stations 0.5 and 0, the flow was dragged tangentially on the surface of the model. The flow on the rudder is normal. The flow in the back of the transom stern is also normal. The conclusions for the highly loaded condition are as follows (the values of flow and propeller potentiometers are 110 (Vs=8 knots) and 55 (RPSs=11.2) respectively): It is necessary to make a filling lightly on the surface between the stations 1.5 and 1. The vortex tube happens over the propeller. In the station 0.5, turbulence was observed in the region over the propeller. Keywords: Flow visualization test, flow visualization methods, fishing boat. Bu çalışmada, Türkiye sularına uygun olarak geliştirilmiş olan balıkçı gemilerinden 148/1 kodlu ana balıkçı gemisinin 148/1C kodlu modelinin yüklü (1.00xT) ve aşırı yüklü (1.25xT) yükleme durumlarındaki akım görüntüleme deneyleri, iplikçik yöntemi kullanılarak gerçekleştirilmiştir. Deneylerde kullanılan bu modelin a geometrik benzerlik oranı 25/3, L boyu 2.4 m ve CB blok katsayısı ise 0.378’dir. Deneyler, İTÜ Gemi İnşaatı ve Deniz Bilimleri Fakültesinin Ata Nutku Gemi Model Deney Laboratuvarındaki Sirkülasyon Kanalı Ünitesinde takıntılı ve model pervaneli olarak yapılmıştır. Akım görüntüleme maddesi olarak kullanılan iplikçikler, orlon iplikten hazırlanmıştır. Modelin iskele tarafındaki, 10 posta sisteminde; 0, Dümen Ekseni, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 8.5, 9, 9.5 ve 10 nolu posta çizgileri üzerine 1 mm çaplı ve 25 mm uzunluklu çiviler, başları sınır tabaka dışında kalacak ve yüzeye dik olacak şekilde uygun aralıklarla çakılmıştır. Sınır tabaka içindeki iplikçikler bordo renkli, sınır tabaka dışındaki iplikçikler ise turuncu renkli olarak seçilmiştir. Bu iplikçiklerin boyları da [25-40 mm] arasında değişmektedir. Yüklü durumdaki deneyler 110 akım potansiyometre değerinde (vm=1.4 m/s; Vs=8 knot) ve 0, 50 ile 55 pervane potansiyometre değerlerinde (RPSm=0, 29.4, 32.3; RPSs=0, 10.2, 11.2) yapılmıştır. Aşırı yüklü durumda ise 110 akım potansiyometre değerinde (vm=1.4 m/s; Vs=8 knot) ve 0 ile 55 pervane potansiyometre değerlerinde (RPSm=0, 32.3; RPSs=0, 11.2) yapılmıştır. Tüm bu deney koşullarında, dijital fotoğraf makinesi ile çekilen deney fotoğraflarının bilgisayar ortamında değerlendirilmesi sonucunda elde edilen bulgular maddeler halinde sıralanmıştır. Anahtar Kelimeler: Akım görüntüleme deneyi, akım görüntüleme yöntemleri, balıkçı gemisi
Long term absolute sea level changes by tide gauge and continuous GPS data
Get PDFNorveç kıyılarındaki ANDENES ve TREGDE mareograf istasyonlarındaki uzun dönemli mutlak deniz seviyesi değişimleri mareograf ve Sabit GPS zaman serilerinin analizi ile araştırılmıştır. Aylık ortalama deniz seviyesi ile Sabit GPS yükseklik zaman serilerindeki periyodik sinyallerin konumsal ve zamansal karakteri Deneysel Ortogonal Fonksiyon ve spektral analiz yöntemleri kullanılarak belirlenmiştir. Hem mareograf hem de Sabit GPS yükseklik zaman serisi doğrusal trendleri En Küçük Karelerle harmonik analiz yöntemiyle hesaplanmıştır. TREGDE’de anlamlı bir deniz seviyesi trendi bulunmazken, ANDENES mareograf istasyonunda uzun dönemli mutlak deniz seviyesinin 2.44 ± 0.21 mm/yıl hızla yükseldiği belirlenmiştir. Bu değer literatürdeki 1-3 mm/yıl düzeyindeki global deniz seviyesi değişimleri ile uyumludur.Anahtar Kelimeler: Mutlak deniz seviyesi, Sabit GPS, Deneysel Ortogonal Fonksiyon analizi, Spektral analiz. Long term absolute sea level changes at ANDENES and TREGDE tide gauges at Norwegian coasts are investigated by the analysis of the tide gauge and Continuous GPS time series. The spatial and temporal character of interannual to interdecadal sea level varitaions in tide gauge monthly mean sea level data and periodic signals in Continuous GPS height time series are determined by using Emprical Ortogonal Function and spectral analysis methods. The linear trends of both tide gauge and Continuous GPS height time series are calculated by harmonic analysis method with Least Squares Estimation. While no significant relative sea level trend is found at TREGDE, 2.04 ± 0.19 mm/year is found at ANDENES. While no significant absolute vertical movement is determined at TGDE and ANDE, the absolute vertical velocity of ANDO Continuous GPS station is 0.40 ± 0.10 mm/year and generally agrees with 0.89 mm/year land uplift determined by a Post Glacial Rebound model. The absolute sea level at ANDENES tide gauge is determined to be rising with a rate of 2.44 ± 0.21 mm/year by combining the vertical velocity of ANDE Continuous GPS station with the relative sea level trend. This value is consistent with the global sea level rise estimates which is in the order of 1-3 mm/year.Keywords: Absolute sea level, Continuous GPS, Emprical Orthogonal Function analysis, Spectral analysis.
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